Imported Upstream version 3.2upstream/3.2

17 files changed, 11273 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
new file mode 100644
index 0000000..275c155
--- /dev/null
+++ b/src/Makefile.am
@@ -0,0 +1,76 @@
+# Automakefile for GNU diffutils programs.
+
+# Copyright (C) 2001-2002, 2006, 2009-2011 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+bin_PROGRAMS = cmp diff diff3 sdiff
+
+localedir = $(datadir)/locale
+
+AM_CPPFLAGS = -I../lib -I$(top_srcdir)/lib
+AM_CFLAGS = $(WARN_CFLAGS) $(WERROR_CFLAGS)
+
+LDADD = \
+  libver.a \
+  ../lib/libdiffutils.a \
+  $(LIBCSTACK) \
+  $(LIBINTL) \
+  $(LIBICONV) \
+  $(LIBSIGSEGV) \
+  $(LIB_CLOCK_GETTIME)
+
+diff_LDADD = $(LDADD)
+cmp_LDADD = $(LDADD)
+sdiff_LDADD = $(LDADD)
+diff3_LDADD = $(LDADD)
+
+cmp_SOURCES = cmp.c
+diff3_SOURCES = diff3.c
+sdiff_SOURCES = sdiff.c
+diff_SOURCES = \
+  analyze.c context.c diff.c dir.c ed.c ifdef.c io.c \
+  normal.c side.c util.c
+noinst_HEADERS = diff.h system.h
+
+MOSTLYCLEANFILES = paths.h paths.ht
+
+cmp.$(OBJEXT) diff3.$(OBJEXT) diff.$(OBJEXT) sdiff.$(OBJEXT): paths.h
+
+gdiff = `echo diff|sed '$(transform)'`
+BUILT_SOURCES = paths.h
+paths.h: Makefile.am
+	$(AM_V_GEN)(echo '#define DEFAULT_DIFF_PROGRAM "'$(gdiff)'"' && \
+	  echo '#define LOCALEDIR "$(localedir)"') >$@t && mv $@t $@
+
+noinst_LIBRARIES = libver.a
+nodist_libver_a_SOURCES = version.c version.h
+
+BUILT_SOURCES += version.c
+version.c: Makefile
+	$(AM_V_GEN)rm -f $@
+	$(AM_V_at)printf '#include <config.h>\n' > $@t
+	$(AM_V_at)printf 'char const *Version = "$(PACKAGE_VERSION)";\n' >> $@t
+	$(AM_V_at)chmod a-w $@t
+	$(AM_V_at)mv $@t $@
+
+BUILT_SOURCES += version.h
+version.h: Makefile
+	$(AM_V_GEN)rm -f $@
+	$(AM_V_at)printf 'extern char const *Version;\n' > $@t
+	$(AM_V_at)chmod a-w $@t
+	$(AM_V_at)mv $@t $@
+
+DISTCLEANFILES = version.c version.h
+MAINTAINERCLEANFILES = $(BUILT_SOURCES)
diff --git a/src/Makefile.in b/src/Makefile.in
new file mode 100644
index 0000000..fd5a046
--- /dev/null
+++ b/src/Makefile.in
@@ -0,0 +1,1413 @@
+# Makefile.in generated by automake 1.11a from Makefile.am.
+# @configure_input@
+
+# Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
+# 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software
+# Foundation, Inc.
+# This Makefile.in is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY, to the extent permitted by law; without
+# even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+# PARTICULAR PURPOSE.
+
+@SET_MAKE@
+
+# Automakefile for GNU diffutils programs.
+
+# Copyright (C) 2001-2002, 2006, 2009-2011 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+
+VPATH = @srcdir@
+pkgdatadir = $(datadir)/@PACKAGE@
+pkgincludedir = $(includedir)/@PACKAGE@
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+am__cd = CDPATH="$${ZSH_VERSION+.}$(PATH_SEPARATOR)" && cd
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+INSTALL_HEADER = $(INSTALL_DATA)
+transform = $(program_transform_name)
+NORMAL_INSTALL = :
+PRE_INSTALL = :
+POST_INSTALL = :
+NORMAL_UNINSTALL = :
+PRE_UNINSTALL = :
+POST_UNINSTALL = :
+build_triplet = @build@
+host_triplet = @host@
+bin_PROGRAMS = cmp$(EXEEXT) diff$(EXEEXT) diff3$(EXEEXT) \
+	sdiff$(EXEEXT)
+subdir = src
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+	$(srcdir)/Makefile.in
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+GNULIB_LSEEK = @GNULIB_LSEEK@
+GNULIB_LSTAT = @GNULIB_LSTAT@
+GNULIB_MALLOC_POSIX = @GNULIB_MALLOC_POSIX@
+GNULIB_MBRLEN = @GNULIB_MBRLEN@
+GNULIB_MBRTOWC = @GNULIB_MBRTOWC@
+GNULIB_MBSCASECMP = @GNULIB_MBSCASECMP@
+GNULIB_MBSCASESTR = @GNULIB_MBSCASESTR@
+GNULIB_MBSCHR = @GNULIB_MBSCHR@
+GNULIB_MBSCSPN = @GNULIB_MBSCSPN@
+GNULIB_MBSINIT = @GNULIB_MBSINIT@
+GNULIB_MBSLEN = @GNULIB_MBSLEN@
+GNULIB_MBSNCASECMP = @GNULIB_MBSNCASECMP@
+GNULIB_MBSNLEN = @GNULIB_MBSNLEN@
+GNULIB_MBSNRTOWCS = @GNULIB_MBSNRTOWCS@
+GNULIB_MBSPBRK = @GNULIB_MBSPBRK@
+GNULIB_MBSPCASECMP = @GNULIB_MBSPCASECMP@
+GNULIB_MBSRCHR = @GNULIB_MBSRCHR@
+GNULIB_MBSRTOWCS = @GNULIB_MBSRTOWCS@
+GNULIB_MBSSEP = @GNULIB_MBSSEP@
+GNULIB_MBSSPN = @GNULIB_MBSSPN@
+GNULIB_MBSSTR = @GNULIB_MBSSTR@
+GNULIB_MBSTOK_R = @GNULIB_MBSTOK_R@
+GNULIB_MBTOWC = @GNULIB_MBTOWC@
+GNULIB_MEMCHR = @GNULIB_MEMCHR@
+GNULIB_MEMMEM = @GNULIB_MEMMEM@
+GNULIB_MEMPCPY = @GNULIB_MEMPCPY@
+GNULIB_MEMRCHR = @GNULIB_MEMRCHR@
+GNULIB_MKDIRAT = @GNULIB_MKDIRAT@
+GNULIB_MKDTEMP = @GNULIB_MKDTEMP@
+GNULIB_MKFIFO = @GNULIB_MKFIFO@
+GNULIB_MKFIFOAT = @GNULIB_MKFIFOAT@
+GNULIB_MKNOD = @GNULIB_MKNOD@
+GNULIB_MKNODAT = @GNULIB_MKNODAT@
+GNULIB_MKOSTEMP = @GNULIB_MKOSTEMP@
+GNULIB_MKOSTEMPS = @GNULIB_MKOSTEMPS@
+GNULIB_MKSTEMP = @GNULIB_MKSTEMP@
+GNULIB_MKSTEMPS = @GNULIB_MKSTEMPS@
+GNULIB_MKTIME = @GNULIB_MKTIME@
+GNULIB_NANOSLEEP = @GNULIB_NANOSLEEP@
+GNULIB_NL_LANGINFO = @GNULIB_NL_LANGINFO@
+GNULIB_NONBLOCKING = @GNULIB_NONBLOCKING@
+GNULIB_OBSTACK_PRINTF = @GNULIB_OBSTACK_PRINTF@
+GNULIB_OBSTACK_PRINTF_POSIX = @GNULIB_OBSTACK_PRINTF_POSIX@
+GNULIB_OPEN = @GNULIB_OPEN@
+GNULIB_OPENAT = @GNULIB_OPENAT@
+GNULIB_PERROR = @GNULIB_PERROR@
+GNULIB_PIPE = @GNULIB_PIPE@
+GNULIB_PIPE2 = @GNULIB_PIPE2@
+GNULIB_POPEN = @GNULIB_POPEN@
+GNULIB_PREAD = @GNULIB_PREAD@
+GNULIB_PRINTF = @GNULIB_PRINTF@
+GNULIB_PRINTF_POSIX = @GNULIB_PRINTF_POSIX@
+GNULIB_PTHREAD_SIGMASK = @GNULIB_PTHREAD_SIGMASK@
+GNULIB_PTSNAME = @GNULIB_PTSNAME@
+GNULIB_PUTC = @GNULIB_PUTC@
+GNULIB_PUTCHAR = @GNULIB_PUTCHAR@
+GNULIB_PUTENV = @GNULIB_PUTENV@
+GNULIB_PUTS = @GNULIB_PUTS@
+GNULIB_PWRITE = @GNULIB_PWRITE@
+GNULIB_RANDOM_R = @GNULIB_RANDOM_R@
+GNULIB_RAWMEMCHR = @GNULIB_RAWMEMCHR@
+GNULIB_READ = @GNULIB_READ@
+GNULIB_READLINK = @GNULIB_READLINK@
+GNULIB_READLINKAT = @GNULIB_READLINKAT@
+GNULIB_REALLOC_POSIX = @GNULIB_REALLOC_POSIX@
+GNULIB_REALPATH = @GNULIB_REALPATH@
+GNULIB_REMOVE = @GNULIB_REMOVE@
+GNULIB_RENAME = @GNULIB_RENAME@
+GNULIB_RENAMEAT = @GNULIB_RENAMEAT@
+GNULIB_RMDIR = @GNULIB_RMDIR@
+GNULIB_RPMATCH = @GNULIB_RPMATCH@
+GNULIB_SCANF = @GNULIB_SCANF@
+GNULIB_SETENV = @GNULIB_SETENV@
+GNULIB_SETLOCALE = @GNULIB_SETLOCALE@
+GNULIB_SIGACTION = @GNULIB_SIGACTION@
+GNULIB_SIGNAL_H_SIGPIPE = @GNULIB_SIGNAL_H_SIGPIPE@
+GNULIB_SIGPROCMASK = @GNULIB_SIGPROCMASK@
+GNULIB_SLEEP = @GNULIB_SLEEP@
+GNULIB_SNPRINTF = @GNULIB_SNPRINTF@
+GNULIB_SPRINTF_POSIX = @GNULIB_SPRINTF_POSIX@
+GNULIB_STAT = @GNULIB_STAT@
+GNULIB_STDIO_H_NONBLOCKING = @GNULIB_STDIO_H_NONBLOCKING@
+GNULIB_STDIO_H_SIGPIPE = @GNULIB_STDIO_H_SIGPIPE@
+GNULIB_STPCPY = @GNULIB_STPCPY@
+GNULIB_STPNCPY = @GNULIB_STPNCPY@
+GNULIB_STRCASESTR = @GNULIB_STRCASESTR@
+GNULIB_STRCHRNUL = @GNULIB_STRCHRNUL@
+GNULIB_STRDUP = @GNULIB_STRDUP@
+GNULIB_STRERROR = @GNULIB_STRERROR@
+GNULIB_STRERROR_R = @GNULIB_STRERROR_R@
+GNULIB_STRNCAT = @GNULIB_STRNCAT@
+GNULIB_STRNDUP = @GNULIB_STRNDUP@
+GNULIB_STRNLEN = @GNULIB_STRNLEN@
+GNULIB_STRPBRK = @GNULIB_STRPBRK@
+GNULIB_STRPTIME = @GNULIB_STRPTIME@
+GNULIB_STRSEP = @GNULIB_STRSEP@
+GNULIB_STRSIGNAL = @GNULIB_STRSIGNAL@
+GNULIB_STRSTR = @GNULIB_STRSTR@
+GNULIB_STRTOD = @GNULIB_STRTOD@
+GNULIB_STRTOIMAX = @GNULIB_STRTOIMAX@
+GNULIB_STRTOK_R = @GNULIB_STRTOK_R@
+GNULIB_STRTOLL = @GNULIB_STRTOLL@
+GNULIB_STRTOULL = @GNULIB_STRTOULL@
+GNULIB_STRTOUMAX = @GNULIB_STRTOUMAX@
+GNULIB_STRVERSCMP = @GNULIB_STRVERSCMP@
+GNULIB_SYMLINK = @GNULIB_SYMLINK@
+GNULIB_SYMLINKAT = @GNULIB_SYMLINKAT@
+GNULIB_SYSTEM_POSIX = @GNULIB_SYSTEM_POSIX@
+GNULIB_TIMEGM = @GNULIB_TIMEGM@
+GNULIB_TIME_R = @GNULIB_TIME_R@
+GNULIB_TMPFILE = @GNULIB_TMPFILE@
+GNULIB_TOWCTRANS = @GNULIB_TOWCTRANS@
+GNULIB_TTYNAME_R = @GNULIB_TTYNAME_R@
+GNULIB_UNISTD_H_GETOPT = @GNULIB_UNISTD_H_GETOPT@
+GNULIB_UNISTD_H_NONBLOCKING = @GNULIB_UNISTD_H_NONBLOCKING@
+GNULIB_UNISTD_H_SIGPIPE = @GNULIB_UNISTD_H_SIGPIPE@
+GNULIB_UNLINK = @GNULIB_UNLINK@
+GNULIB_UNLINKAT = @GNULIB_UNLINKAT@
+GNULIB_UNLOCKPT = @GNULIB_UNLOCKPT@
+GNULIB_UNSETENV = @GNULIB_UNSETENV@
+GNULIB_USLEEP = @GNULIB_USLEEP@
+GNULIB_UTIMENSAT = @GNULIB_UTIMENSAT@
+GNULIB_VASPRINTF = @GNULIB_VASPRINTF@
+GNULIB_VDPRINTF = @GNULIB_VDPRINTF@
+GNULIB_VFPRINTF = @GNULIB_VFPRINTF@
+GNULIB_VFPRINTF_POSIX = @GNULIB_VFPRINTF_POSIX@
+GNULIB_VFSCANF = @GNULIB_VFSCANF@
+GNULIB_VPRINTF = @GNULIB_VPRINTF@
+GNULIB_VPRINTF_POSIX = @GNULIB_VPRINTF_POSIX@
+GNULIB_VSCANF = @GNULIB_VSCANF@
+GNULIB_VSNPRINTF = @GNULIB_VSNPRINTF@
+GNULIB_VSPRINTF_POSIX = @GNULIB_VSPRINTF_POSIX@
+GNULIB_WAITPID = @GNULIB_WAITPID@
+GNULIB_WARN_CFLAGS = @GNULIB_WARN_CFLAGS@
+GNULIB_WCPCPY = @GNULIB_WCPCPY@
+GNULIB_WCPNCPY = @GNULIB_WCPNCPY@
+GNULIB_WCRTOMB = @GNULIB_WCRTOMB@
+GNULIB_WCSCASECMP = @GNULIB_WCSCASECMP@
+GNULIB_WCSCAT = @GNULIB_WCSCAT@
+GNULIB_WCSCHR = @GNULIB_WCSCHR@
+GNULIB_WCSCMP = @GNULIB_WCSCMP@
+GNULIB_WCSCOLL = @GNULIB_WCSCOLL@
+GNULIB_WCSCPY = @GNULIB_WCSCPY@
+GNULIB_WCSCSPN = @GNULIB_WCSCSPN@
+GNULIB_WCSDUP = @GNULIB_WCSDUP@
+GNULIB_WCSLEN = @GNULIB_WCSLEN@
+GNULIB_WCSNCASECMP = @GNULIB_WCSNCASECMP@
+GNULIB_WCSNCAT = @GNULIB_WCSNCAT@
+GNULIB_WCSNCMP = @GNULIB_WCSNCMP@
+GNULIB_WCSNCPY = @GNULIB_WCSNCPY@
+GNULIB_WCSNLEN = @GNULIB_WCSNLEN@
+GNULIB_WCSNRTOMBS = @GNULIB_WCSNRTOMBS@
+GNULIB_WCSPBRK = @GNULIB_WCSPBRK@
+GNULIB_WCSRCHR = @GNULIB_WCSRCHR@
+GNULIB_WCSRTOMBS = @GNULIB_WCSRTOMBS@
+GNULIB_WCSSPN = @GNULIB_WCSSPN@
+GNULIB_WCSSTR = @GNULIB_WCSSTR@
+GNULIB_WCSTOK = @GNULIB_WCSTOK@
+GNULIB_WCSWIDTH = @GNULIB_WCSWIDTH@
+GNULIB_WCSXFRM = @GNULIB_WCSXFRM@
+GNULIB_WCTOB = @GNULIB_WCTOB@
+GNULIB_WCTOMB = @GNULIB_WCTOMB@
+GNULIB_WCTRANS = @GNULIB_WCTRANS@
+GNULIB_WCTYPE = @GNULIB_WCTYPE@
+GNULIB_WCWIDTH = @GNULIB_WCWIDTH@
+GNULIB_WMEMCHR = @GNULIB_WMEMCHR@
+GNULIB_WMEMCMP = @GNULIB_WMEMCMP@
+GNULIB_WMEMCPY = @GNULIB_WMEMCPY@
+GNULIB_WMEMMOVE = @GNULIB_WMEMMOVE@
+GNULIB_WMEMSET = @GNULIB_WMEMSET@
+GNULIB_WRITE = @GNULIB_WRITE@
+GNULIB__EXIT = @GNULIB__EXIT@
+GREP = @GREP@
+HAVE_ATOLL = @HAVE_ATOLL@
+HAVE_BTOWC = @HAVE_BTOWC@
+HAVE_CANONICALIZE_FILE_NAME = @HAVE_CANONICALIZE_FILE_NAME@
+HAVE_CHOWN = @HAVE_CHOWN@
+HAVE_DECL_ENVIRON = @HAVE_DECL_ENVIRON@
+HAVE_DECL_FCHDIR = @HAVE_DECL_FCHDIR@
+HAVE_DECL_FPURGE = @HAVE_DECL_FPURGE@
+HAVE_DECL_FSEEKO = @HAVE_DECL_FSEEKO@
+HAVE_DECL_FTELLO = @HAVE_DECL_FTELLO@
+HAVE_DECL_GETDELIM = @HAVE_DECL_GETDELIM@
+HAVE_DECL_GETDOMAINNAME = @HAVE_DECL_GETDOMAINNAME@
+HAVE_DECL_GETLINE = @HAVE_DECL_GETLINE@
+HAVE_DECL_GETLOADAVG = @HAVE_DECL_GETLOADAVG@
+HAVE_DECL_GETLOGIN_R = @HAVE_DECL_GETLOGIN_R@
+HAVE_DECL_GETPAGESIZE = @HAVE_DECL_GETPAGESIZE@
+HAVE_DECL_GETUSERSHELL = @HAVE_DECL_GETUSERSHELL@
+HAVE_DECL_IMAXABS = @HAVE_DECL_IMAXABS@
+HAVE_DECL_IMAXDIV = @HAVE_DECL_IMAXDIV@
+HAVE_DECL_LOCALTIME_R = @HAVE_DECL_LOCALTIME_R@
+HAVE_DECL_MEMMEM = @HAVE_DECL_MEMMEM@
+HAVE_DECL_MEMRCHR = @HAVE_DECL_MEMRCHR@
+HAVE_DECL_OBSTACK_PRINTF = @HAVE_DECL_OBSTACK_PRINTF@
+HAVE_DECL_SETENV = @HAVE_DECL_SETENV@
+HAVE_DECL_SNPRINTF = @HAVE_DECL_SNPRINTF@
+HAVE_DECL_STRDUP = @HAVE_DECL_STRDUP@
+HAVE_DECL_STRERROR_R = @HAVE_DECL_STRERROR_R@
+HAVE_DECL_STRNCASECMP = @HAVE_DECL_STRNCASECMP@
+HAVE_DECL_STRNDUP = @HAVE_DECL_STRNDUP@
+HAVE_DECL_STRNLEN = @HAVE_DECL_STRNLEN@
+HAVE_DECL_STRSIGNAL = @HAVE_DECL_STRSIGNAL@
+HAVE_DECL_STRTOIMAX = @HAVE_DECL_STRTOIMAX@
+HAVE_DECL_STRTOK_R = @HAVE_DECL_STRTOK_R@
+HAVE_DECL_STRTOUMAX = @HAVE_DECL_STRTOUMAX@
+HAVE_DECL_TTYNAME_R = @HAVE_DECL_TTYNAME_R@
+HAVE_DECL_UNSETENV = @HAVE_DECL_UNSETENV@
+HAVE_DECL_VSNPRINTF = @HAVE_DECL_VSNPRINTF@
+HAVE_DECL_WCTOB = @HAVE_DECL_WCTOB@
+HAVE_DECL_WCWIDTH = @HAVE_DECL_WCWIDTH@
+HAVE_DPRINTF = @HAVE_DPRINTF@
+HAVE_DUP2 = @HAVE_DUP2@
+HAVE_DUP3 = @HAVE_DUP3@
+HAVE_DUPLOCALE = @HAVE_DUPLOCALE@
+HAVE_EUIDACCESS = @HAVE_EUIDACCESS@
+HAVE_FACCESSAT = @HAVE_FACCESSAT@
+HAVE_FCHDIR = @HAVE_FCHDIR@
+HAVE_FCHMODAT = @HAVE_FCHMODAT@
+HAVE_FCHOWNAT = @HAVE_FCHOWNAT@
+HAVE_FCNTL = @HAVE_FCNTL@
+HAVE_FEATURES_H = @HAVE_FEATURES_H@
+HAVE_FFS = @HAVE_FFS@
+HAVE_FFSL = @HAVE_FFSL@
+HAVE_FFSLL = @HAVE_FFSLL@
+HAVE_FSEEKO = @HAVE_FSEEKO@
+HAVE_FSTATAT = @HAVE_FSTATAT@
+HAVE_FSYNC = @HAVE_FSYNC@
+HAVE_FTELLO = @HAVE_FTELLO@
+HAVE_FTRUNCATE = @HAVE_FTRUNCATE@
+HAVE_FUTIMENS = @HAVE_FUTIMENS@
+HAVE_GETDTABLESIZE = @HAVE_GETDTABLESIZE@
+HAVE_GETGROUPS = @HAVE_GETGROUPS@
+HAVE_GETHOSTNAME = @HAVE_GETHOSTNAME@
+HAVE_GETLOGIN = @HAVE_GETLOGIN@
+HAVE_GETOPT_H = @HAVE_GETOPT_H@
+HAVE_GETPAGESIZE = @HAVE_GETPAGESIZE@
+HAVE_GETSUBOPT = @HAVE_GETSUBOPT@
+HAVE_GETTIMEOFDAY = @HAVE_GETTIMEOFDAY@
+HAVE_GRANTPT = @HAVE_GRANTPT@
+HAVE_GROUP_MEMBER = @HAVE_GROUP_MEMBER@
+HAVE_INTTYPES_H = @HAVE_INTTYPES_H@
+HAVE_ISWBLANK = @HAVE_ISWBLANK@
+HAVE_ISWCNTRL = @HAVE_ISWCNTRL@
+HAVE_LANGINFO_CODESET = @HAVE_LANGINFO_CODESET@
+HAVE_LANGINFO_ERA = @HAVE_LANGINFO_ERA@
+HAVE_LANGINFO_H = @HAVE_LANGINFO_H@
+HAVE_LANGINFO_T_FMT_AMPM = @HAVE_LANGINFO_T_FMT_AMPM@
+HAVE_LANGINFO_YESEXPR = @HAVE_LANGINFO_YESEXPR@
+HAVE_LCHMOD = @HAVE_LCHMOD@
+HAVE_LCHOWN = @HAVE_LCHOWN@
+HAVE_LIBSIGSEGV = @HAVE_LIBSIGSEGV@
+HAVE_LINK = @HAVE_LINK@
+HAVE_LINKAT = @HAVE_LINKAT@
+HAVE_LONG_LONG_INT = @HAVE_LONG_LONG_INT@
+HAVE_LSTAT = @HAVE_LSTAT@
+HAVE_MBRLEN = @HAVE_MBRLEN@
+HAVE_MBRTOWC = @HAVE_MBRTOWC@
+HAVE_MBSINIT = @HAVE_MBSINIT@
+HAVE_MBSLEN = @HAVE_MBSLEN@
+HAVE_MBSNRTOWCS = @HAVE_MBSNRTOWCS@
+HAVE_MBSRTOWCS = @HAVE_MBSRTOWCS@
+HAVE_MEMCHR = @HAVE_MEMCHR@
+HAVE_MEMPCPY = @HAVE_MEMPCPY@
+HAVE_MKDIRAT = @HAVE_MKDIRAT@
+HAVE_MKDTEMP = @HAVE_MKDTEMP@
+HAVE_MKFIFO = @HAVE_MKFIFO@
+HAVE_MKFIFOAT = @HAVE_MKFIFOAT@
+HAVE_MKNOD = @HAVE_MKNOD@
+HAVE_MKNODAT = @HAVE_MKNODAT@
+HAVE_MKOSTEMP = @HAVE_MKOSTEMP@
+HAVE_MKOSTEMPS = @HAVE_MKOSTEMPS@
+HAVE_MKSTEMP = @HAVE_MKSTEMP@
+HAVE_MKSTEMPS = @HAVE_MKSTEMPS@
+HAVE_NANOSLEEP = @HAVE_NANOSLEEP@
+HAVE_NL_LANGINFO = @HAVE_NL_LANGINFO@
+HAVE_OPENAT = @HAVE_OPENAT@
+HAVE_OS_H = @HAVE_OS_H@
+HAVE_PIPE = @HAVE_PIPE@
+HAVE_PIPE2 = @HAVE_PIPE2@
+HAVE_POSIX_SIGNALBLOCKING = @HAVE_POSIX_SIGNALBLOCKING@
+HAVE_PREAD = @HAVE_PREAD@
+HAVE_PTHREAD_SIGMASK = @HAVE_PTHREAD_SIGMASK@
+HAVE_PTSNAME = @HAVE_PTSNAME@
+HAVE_PWRITE = @HAVE_PWRITE@
+HAVE_RANDOM_H = @HAVE_RANDOM_H@
+HAVE_RANDOM_R = @HAVE_RANDOM_R@
+HAVE_RAWMEMCHR = @HAVE_RAWMEMCHR@
+HAVE_READLINK = @HAVE_READLINK@
+HAVE_READLINKAT = @HAVE_READLINKAT@
+HAVE_REALPATH = @HAVE_REALPATH@
+HAVE_RENAMEAT = @HAVE_RENAMEAT@
+HAVE_RPMATCH = @HAVE_RPMATCH@
+HAVE_SETENV = @HAVE_SETENV@
+HAVE_SIGACTION = @HAVE_SIGACTION@
+HAVE_SIGHANDLER_T = @HAVE_SIGHANDLER_T@
+HAVE_SIGINFO_T = @HAVE_SIGINFO_T@
+HAVE_SIGNED_SIG_ATOMIC_T = @HAVE_SIGNED_SIG_ATOMIC_T@
+HAVE_SIGNED_WCHAR_T = @HAVE_SIGNED_WCHAR_T@
+HAVE_SIGNED_WINT_T = @HAVE_SIGNED_WINT_T@
+HAVE_SIGSET_T = @HAVE_SIGSET_T@
+HAVE_SLEEP = @HAVE_SLEEP@
+HAVE_STDINT_H = @HAVE_STDINT_H@
+HAVE_STPCPY = @HAVE_STPCPY@
+HAVE_STPNCPY = @HAVE_STPNCPY@
+HAVE_STRCASECMP = @HAVE_STRCASECMP@
+HAVE_STRCASESTR = @HAVE_STRCASESTR@
+HAVE_STRCHRNUL = @HAVE_STRCHRNUL@
+HAVE_STRPBRK = @HAVE_STRPBRK@
+HAVE_STRPTIME = @HAVE_STRPTIME@
+HAVE_STRSEP = @HAVE_STRSEP@
+HAVE_STRTOD = @HAVE_STRTOD@
+HAVE_STRTOLL = @HAVE_STRTOLL@
+HAVE_STRTOULL = @HAVE_STRTOULL@
+HAVE_STRUCT_RANDOM_DATA = @HAVE_STRUCT_RANDOM_DATA@
+HAVE_STRUCT_SIGACTION_SA_SIGACTION = @HAVE_STRUCT_SIGACTION_SA_SIGACTION@
+HAVE_STRUCT_TIMEVAL = @HAVE_STRUCT_TIMEVAL@
+HAVE_STRVERSCMP = @HAVE_STRVERSCMP@
+HAVE_SYMLINK = @HAVE_SYMLINK@
+HAVE_SYMLINKAT = @HAVE_SYMLINKAT@
+HAVE_SYS_BITYPES_H = @HAVE_SYS_BITYPES_H@
+HAVE_SYS_INTTYPES_H = @HAVE_SYS_INTTYPES_H@
+HAVE_SYS_LOADAVG_H = @HAVE_SYS_LOADAVG_H@
+HAVE_SYS_PARAM_H = @HAVE_SYS_PARAM_H@
+HAVE_SYS_TIME_H = @HAVE_SYS_TIME_H@
+HAVE_SYS_TYPES_H = @HAVE_SYS_TYPES_H@
+HAVE_TIMEGM = @HAVE_TIMEGM@
+HAVE_TYPE_VOLATILE_SIG_ATOMIC_T = @HAVE_TYPE_VOLATILE_SIG_ATOMIC_T@
+HAVE_UNISTD_H = @HAVE_UNISTD_H@
+HAVE_UNLINKAT = @HAVE_UNLINKAT@
+HAVE_UNLOCKPT = @HAVE_UNLOCKPT@
+HAVE_UNSIGNED_LONG_LONG_INT = @HAVE_UNSIGNED_LONG_LONG_INT@
+HAVE_USLEEP = @HAVE_USLEEP@
+HAVE_UTIMENSAT = @HAVE_UTIMENSAT@
+HAVE_VASPRINTF = @HAVE_VASPRINTF@
+HAVE_VDPRINTF = @HAVE_VDPRINTF@
+HAVE_WCHAR_H = @HAVE_WCHAR_H@
+HAVE_WCHAR_T = @HAVE_WCHAR_T@
+HAVE_WCPCPY = @HAVE_WCPCPY@
+HAVE_WCPNCPY = @HAVE_WCPNCPY@
+HAVE_WCRTOMB = @HAVE_WCRTOMB@
+HAVE_WCSCASECMP = @HAVE_WCSCASECMP@
+HAVE_WCSCAT = @HAVE_WCSCAT@
+HAVE_WCSCHR = @HAVE_WCSCHR@
+HAVE_WCSCMP = @HAVE_WCSCMP@
+HAVE_WCSCOLL = @HAVE_WCSCOLL@
+HAVE_WCSCPY = @HAVE_WCSCPY@
+HAVE_WCSCSPN = @HAVE_WCSCSPN@
+HAVE_WCSDUP = @HAVE_WCSDUP@
+HAVE_WCSLEN = @HAVE_WCSLEN@
+HAVE_WCSNCASECMP = @HAVE_WCSNCASECMP@
+HAVE_WCSNCAT = @HAVE_WCSNCAT@
+HAVE_WCSNCMP = @HAVE_WCSNCMP@
+HAVE_WCSNCPY = @HAVE_WCSNCPY@
+HAVE_WCSNLEN = @HAVE_WCSNLEN@
+HAVE_WCSNRTOMBS = @HAVE_WCSNRTOMBS@
+HAVE_WCSPBRK = @HAVE_WCSPBRK@
+HAVE_WCSRCHR = @HAVE_WCSRCHR@
+HAVE_WCSRTOMBS = @HAVE_WCSRTOMBS@
+HAVE_WCSSPN = @HAVE_WCSSPN@
+HAVE_WCSSTR = @HAVE_WCSSTR@
+HAVE_WCSTOK = @HAVE_WCSTOK@
+HAVE_WCSWIDTH = @HAVE_WCSWIDTH@
+HAVE_WCSXFRM = @HAVE_WCSXFRM@
+HAVE_WCTRANS_T = @HAVE_WCTRANS_T@
+HAVE_WCTYPE_H = @HAVE_WCTYPE_H@
+HAVE_WCTYPE_T = @HAVE_WCTYPE_T@
+HAVE_WINSOCK2_H = @HAVE_WINSOCK2_H@
+HAVE_WINT_T = @HAVE_WINT_T@
+HAVE_WMEMCHR = @HAVE_WMEMCHR@
+HAVE_WMEMCMP = @HAVE_WMEMCMP@
+HAVE_WMEMCPY = @HAVE_WMEMCPY@
+HAVE_WMEMMOVE = @HAVE_WMEMMOVE@
+HAVE_WMEMSET = @HAVE_WMEMSET@
+HAVE_XLOCALE_H = @HAVE_XLOCALE_H@
+HAVE__BOOL = @HAVE__BOOL@
+HAVE__EXIT = @HAVE__EXIT@
+HELP2MAN = @HELP2MAN@
+ICONV_CONST = @ICONV_CONST@
+ICONV_H = @ICONV_H@
+INCLUDE_NEXT = @INCLUDE_NEXT@
+INCLUDE_NEXT_AS_FIRST_DIRECTIVE = @INCLUDE_NEXT_AS_FIRST_DIRECTIVE@
+INSTALL = @INSTALL@
+INSTALL_DATA = @INSTALL_DATA@
+INSTALL_PROGRAM = @INSTALL_PROGRAM@
+INSTALL_SCRIPT = @INSTALL_SCRIPT@
+INSTALL_STRIP_PROGRAM = @INSTALL_STRIP_PROGRAM@
+INT32_MAX_LT_INTMAX_MAX = @INT32_MAX_LT_INTMAX_MAX@
+INT64_MAX_EQ_LONG_MAX = @INT64_MAX_EQ_LONG_MAX@
+INTLLIBS = @INTLLIBS@
+INTL_MACOSX_LIBS = @INTL_MACOSX_LIBS@
+LDFLAGS = @LDFLAGS@
+LIBCSTACK = @LIBCSTACK@
+LIBDIFFUTILS_LIBDEPS = @LIBDIFFUTILS_LIBDEPS@
+LIBDIFFUTILS_LTLIBDEPS = @LIBDIFFUTILS_LTLIBDEPS@
+LIBICONV = @LIBICONV@
+LIBINTL = @LIBINTL@
+LIBOBJS = @LIBOBJS@
+LIBS = @LIBS@
+LIBSIGSEGV = @LIBSIGSEGV@
+LIBSIGSEGV_PREFIX = @LIBSIGSEGV_PREFIX@
+LIBTESTS_LIBDEPS = @LIBTESTS_LIBDEPS@
+LIBUNISTRING_UNISTR_H = @LIBUNISTRING_UNISTR_H@
+LIBUNISTRING_UNITYPES_H = @LIBUNISTRING_UNITYPES_H@
+LIBUNISTRING_UNIWIDTH_H = @LIBUNISTRING_UNIWIDTH_H@
+LIB_CLOCK_GETTIME = @LIB_CLOCK_GETTIME@
+LOCALCHARSET_TESTS_ENVIRONMENT = @LOCALCHARSET_TESTS_ENVIRONMENT@
+LOCALE_FR = @LOCALE_FR@
+LOCALE_FR_UTF8 = @LOCALE_FR_UTF8@
+LOCALE_JA = @LOCALE_JA@
+LOCALE_TR_UTF8 = @LOCALE_TR_UTF8@
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+	        && { if test -f $@; then exit 0; else break; fi; }; \
+	      exit 1;; \
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+	$(am__cd) $(top_srcdir) && \
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+	$(AM_V_at)-rm -f libver.a
+	$(AM_V_AR)$(libver_a_AR) libver.a $(libver_a_OBJECTS) $(libver_a_LIBADD)
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+	  { d=$$3; if (dirs[d] != 1) { print "d", d; dirs[d] = 1 } \
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+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/util.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/version.Po@am__quote@
+
+.c.o:
+@am__fastdepCC_TRUE@	$(AM_V_CC)$(COMPILE) -MT $@ -MD -MP -MF $(DEPDIR)/$*.Tpo -c -o $@ $<
+@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/$*.Tpo $(DEPDIR)/$*.Po
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+@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/$*.Tpo $(DEPDIR)/$*.Po
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+	    if test -f "$$i"; then echo $$i; else echo $(srcdir)/$$i; fi; \
+	  done | \
+	  $(AWK) '{ files[$$0] = 1; nonempty = 1; } \
+	      END { if (nonempty) { for (i in files) print i; }; }'`; \
+	mkid -fID $$unique
+tags: TAGS
+
+TAGS:  $(HEADERS) $(SOURCES)  $(TAGS_DEPENDENCIES) \
+		$(TAGS_FILES) $(LISP)
+	set x; \
+	here=`pwd`; \
+	list='$(SOURCES) $(HEADERS)  $(LISP) $(TAGS_FILES)'; \
+	unique=`for i in $$list; do \
+	    if test -f "$$i"; then echo $$i; else echo $(srcdir)/$$i; fi; \
+	  done | \
+	  $(AWK) '{ files[$$0] = 1; nonempty = 1; } \
+	      END { if (nonempty) { for (i in files) print i; }; }'`; \
+	shift; \
+	if test -z "$(ETAGS_ARGS)$$*$$unique"; then :; else \
+	  test -n "$$unique" || unique=$$empty_fix; \
+	  if test $$# -gt 0; then \
+	    $(ETAGS) $(ETAGSFLAGS) $(AM_ETAGSFLAGS) $(ETAGS_ARGS) \
+	      "$$@" $$unique; \
+	  else \
+	    $(ETAGS) $(ETAGSFLAGS) $(AM_ETAGSFLAGS) $(ETAGS_ARGS) \
+	      $$unique; \
+	  fi; \
+	fi
+ctags: CTAGS
+CTAGS:  $(HEADERS) $(SOURCES)  $(TAGS_DEPENDENCIES) \
+		$(TAGS_FILES) $(LISP)
+	list='$(SOURCES) $(HEADERS)  $(LISP) $(TAGS_FILES)'; \
+	unique=`for i in $$list; do \
+	    if test -f "$$i"; then echo $$i; else echo $(srcdir)/$$i; fi; \
+	  done | \
+	  $(AWK) '{ files[$$0] = 1; nonempty = 1; } \
+	      END { if (nonempty) { for (i in files) print i; }; }'`; \
+	test -z "$(CTAGS_ARGS)$$unique" \
+	  || $(CTAGS) $(CTAGSFLAGS) $(AM_CTAGSFLAGS) $(CTAGS_ARGS) \
+	     $$unique
+
+GTAGS:
+	here=`$(am__cd) $(top_builddir) && pwd` \
+	  && $(am__cd) $(top_srcdir) \
+	  && gtags -i $(GTAGS_ARGS) "$$here"
+
+cscopelist:  $(HEADERS) $(SOURCES) $(LISP)
+	list='$(SOURCES) $(HEADERS) $(LISP)'; \
+	case "$(srcdir)" in \
+	  [\\/]* | ?:[\\/]*) sdir="$(srcdir)" ;; \
+	  *) sdir=$(subdir)/$(srcdir) ;; \
+	esac; \
+	for i in $$list; do \
+	  if test -f "$$i"; then \
+	    echo "$(subdir)/$$i"; \
+	  else \
+	    echo "$$sdir/$$i"; \
+	  fi; \
+	done >> $(top_builddir)/cscope.files
+
+distclean-tags:
+	-rm -f TAGS ID GTAGS GRTAGS GSYMS GPATH tags
+
+distdir: $(DISTFILES)
+	@srcdirstrip=`echo "$(srcdir)" | sed 's/[].[^$$\\*]/\\\\&/g'`; \
+	topsrcdirstrip=`echo "$(top_srcdir)" | sed 's/[].[^$$\\*]/\\\\&/g'`; \
+	list='$(DISTFILES)'; \
+	  dist_files=`for file in $$list; do echo $$file; done | \
+	  sed -e "s|^$$srcdirstrip/||;t" \
+	      -e "s|^$$topsrcdirstrip/|$(top_builddir)/|;t"`; \
+	case $$dist_files in \
+	  */*) $(MKDIR_P) `echo "$$dist_files" | \
+			   sed '/\//!d;s|^|$(distdir)/|;s,/[^/]*$$,,' | \
+			   sort -u` ;; \
+	esac; \
+	for file in $$dist_files; do \
+	  if test -f $$file || test -d $$file; then d=.; else d=$(srcdir); fi; \
+	  if test -d $$d/$$file; then \
+	    dir=`echo "/$$file" | sed -e 's,/[^/]*$$,,'`; \
+	    if test -d "$(distdir)/$$file"; then \
+	      find "$(distdir)/$$file" -type d ! -perm -700 -exec chmod u+rwx {} \;; \
+	    fi; \
+	    if test -d $(srcdir)/$$file && test $$d != $(srcdir); then \
+	      cp -fpR $(srcdir)/$$file "$(distdir)$$dir" || exit 1; \
+	      find "$(distdir)/$$file" -type d ! -perm -700 -exec chmod u+rwx {} \;; \
+	    fi; \
+	    cp -fpR $$d/$$file "$(distdir)$$dir" || exit 1; \
+	  else \
+	    test -f "$(distdir)/$$file" \
+	    || cp -p $$d/$$file "$(distdir)/$$file" \
+	    || exit 1; \
+	  fi; \
+	done
+check-am: all-am
+check: $(BUILT_SOURCES)
+	$(MAKE) $(AM_MAKEFLAGS) check-am
+all-am: Makefile $(LIBRARIES) $(PROGRAMS) $(HEADERS)
+installdirs:
+	for dir in "$(DESTDIR)$(bindir)"; do \
+	  test -z "$$dir" || $(MKDIR_P) "$$dir"; \
+	done
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+	$(MAKE) $(AM_MAKEFLAGS) install-am
+install-exec: install-exec-am
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+install-am: all-am
+	@$(MAKE) $(AM_MAKEFLAGS) install-exec-am install-data-am
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+installcheck: installcheck-am
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+	if test -z '$(STRIP)'; then \
+	  $(MAKE) $(AM_MAKEFLAGS) INSTALL_PROGRAM="$(INSTALL_STRIP_PROGRAM)" \
+	    install_sh_PROGRAM="$(INSTALL_STRIP_PROGRAM)" INSTALL_STRIP_FLAG=-s \
+	      install; \
+	else \
+	  $(MAKE) $(AM_MAKEFLAGS) INSTALL_PROGRAM="$(INSTALL_STRIP_PROGRAM)" \
+	    install_sh_PROGRAM="$(INSTALL_STRIP_PROGRAM)" INSTALL_STRIP_FLAG=-s \
+	    "INSTALL_PROGRAM_ENV=STRIPPROG='$(STRIP)'" install; \
+	fi
+mostlyclean-generic:
+	-test -z "$(MOSTLYCLEANFILES)" || rm -f $(MOSTLYCLEANFILES)
+
+clean-generic:
+
+distclean-generic:
+	-test -z "$(CONFIG_CLEAN_FILES)" || rm -f $(CONFIG_CLEAN_FILES)
+	-test . = "$(srcdir)" || test -z "$(CONFIG_CLEAN_VPATH_FILES)" || rm -f $(CONFIG_CLEAN_VPATH_FILES)
+	-test -z "$(DISTCLEANFILES)" || rm -f $(DISTCLEANFILES)
+
+maintainer-clean-generic:
+	@echo "This command is intended for maintainers to use"
+	@echo "it deletes files that may require special tools to rebuild."
+	-test -z "$(BUILT_SOURCES)" || rm -f $(BUILT_SOURCES)
+	-test -z "$(MAINTAINERCLEANFILES)" || rm -f $(MAINTAINERCLEANFILES)
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+clean-am: clean-binPROGRAMS clean-generic clean-noinstLIBRARIES \
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+	-rm -rf ./$(DEPDIR)
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+	distclean-tags
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+	clean-generic clean-noinstLIBRARIES cscopelist ctags distclean \
+	distclean-compile distclean-generic distclean-tags distdir dvi \
+	dvi-am html html-am info info-am install install-am \
+	install-binPROGRAMS install-data install-data-am install-dvi \
+	install-dvi-am install-exec install-exec-am install-html \
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+	install-pdf install-pdf-am install-ps install-ps-am \
+	install-strip installcheck installcheck-am installdirs \
+	maintainer-clean maintainer-clean-generic mostlyclean \
+	mostlyclean-compile mostlyclean-generic pdf pdf-am ps ps-am \
+	tags uninstall uninstall-am uninstall-binPROGRAMS
+
+
+cmp.$(OBJEXT) diff3.$(OBJEXT) diff.$(OBJEXT) sdiff.$(OBJEXT): paths.h
+paths.h: Makefile.am
+	$(AM_V_GEN)(echo '#define DEFAULT_DIFF_PROGRAM "'$(gdiff)'"' && \
+	  echo '#define LOCALEDIR "$(localedir)"') >$@t && mv $@t $@
+version.c: Makefile
+	$(AM_V_GEN)rm -f $@
+	$(AM_V_at)printf '#include <config.h>\n' > $@t
+	$(AM_V_at)printf 'char const *Version = "$(PACKAGE_VERSION)";\n' >> $@t
+	$(AM_V_at)chmod a-w $@t
+	$(AM_V_at)mv $@t $@
+version.h: Makefile
+	$(AM_V_GEN)rm -f $@
+	$(AM_V_at)printf 'extern char const *Version;\n' > $@t
+	$(AM_V_at)chmod a-w $@t
+	$(AM_V_at)mv $@t $@
+
+# Tell versions [3.59,3.63) of GNU make to not export all variables.
+# Otherwise a system limit (for SysV at least) may be exceeded.
+.NOEXPORT:
diff --git a/src/analyze.c b/src/analyze.c
new file mode 100644
index 0000000..f88c45e
--- /dev/null
+++ b/src/analyze.c
@@ -0,0 +1,723 @@
+/* Analyze file differences for GNU DIFF.
+
+   Copyright (C) 1988-1989, 1992-1995, 1998, 2001-2002, 2004, 2006-2007,
+   2009-2011 Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "diff.h"
+#include <cmpbuf.h>
+#include <error.h>
+#include <file-type.h>
+#include <xalloc.h>
+
+/* The core of the Diff algorithm.  */
+#define ELEMENT lin
+#define EQUAL(x,y) ((x) == (y))
+#define OFFSET lin
+#define EXTRA_CONTEXT_FIELDS /* none */
+#define NOTE_DELETE(c, xoff) (files[0].changed[files[0].realindexes[xoff]] = 1)
+#define NOTE_INSERT(c, yoff) (files[1].changed[files[1].realindexes[yoff]] = 1)
+#define USE_HEURISTIC 1
+#include <diffseq.h>
+
+/* Discard lines from one file that have no matches in the other file.
+
+   A line which is discarded will not be considered by the actual
+   comparison algorithm; it will be as if that line were not in the file.
+   The file's `realindexes' table maps virtual line numbers
+   (which don't count the discarded lines) into real line numbers;
+   this is how the actual comparison algorithm produces results
+   that are comprehensible when the discarded lines are counted.
+
+   When we discard a line, we also mark it as a deletion or insertion
+   so that it will be printed in the output.  */
+
+static void
+discard_confusing_lines (struct file_data filevec[])
+{
+  int f;
+  lin i;
+  char *discarded[2];
+  lin *equiv_count[2];
+  lin *p;
+
+  /* Allocate our results.  */
+  p = xmalloc ((filevec[0].buffered_lines + filevec[1].buffered_lines)
+	       * (2 * sizeof *p));
+  for (f = 0; f < 2; f++)
+    {
+      filevec[f].undiscarded = p;  p += filevec[f].buffered_lines;
+      filevec[f].realindexes = p;  p += filevec[f].buffered_lines;
+    }
+
+  /* Set up equiv_count[F][I] as the number of lines in file F
+     that fall in equivalence class I.  */
+
+  p = zalloc (filevec[0].equiv_max * (2 * sizeof *p));
+  equiv_count[0] = p;
+  equiv_count[1] = p + filevec[0].equiv_max;
+
+  for (i = 0; i < filevec[0].buffered_lines; ++i)
+    ++equiv_count[0][filevec[0].equivs[i]];
+  for (i = 0; i < filevec[1].buffered_lines; ++i)
+    ++equiv_count[1][filevec[1].equivs[i]];
+
+  /* Set up tables of which lines are going to be discarded.  */
+
+  discarded[0] = zalloc (filevec[0].buffered_lines
+			 + filevec[1].buffered_lines);
+  discarded[1] = discarded[0] + filevec[0].buffered_lines;
+
+  /* Mark to be discarded each line that matches no line of the other file.
+     If a line matches many lines, mark it as provisionally discardable.  */
+
+  for (f = 0; f < 2; f++)
+    {
+      size_t end = filevec[f].buffered_lines;
+      char *discards = discarded[f];
+      lin *counts = equiv_count[1 - f];
+      lin *equivs = filevec[f].equivs;
+      size_t many = 5;
+      size_t tem = end / 64;
+
+      /* Multiply MANY by approximate square root of number of lines.
+	 That is the threshold for provisionally discardable lines.  */
+      while ((tem = tem >> 2) > 0)
+	many *= 2;
+
+      for (i = 0; i < end; i++)
+	{
+	  lin nmatch;
+	  if (equivs[i] == 0)
+	    continue;
+	  nmatch = counts[equivs[i]];
+	  if (nmatch == 0)
+	    discards[i] = 1;
+	  else if (nmatch > many)
+	    discards[i] = 2;
+	}
+    }
+
+  /* Don't really discard the provisional lines except when they occur
+     in a run of discardables, with nonprovisionals at the beginning
+     and end.  */
+
+  for (f = 0; f < 2; f++)
+    {
+      lin end = filevec[f].buffered_lines;
+      register char *discards = discarded[f];
+
+      for (i = 0; i < end; i++)
+	{
+	  /* Cancel provisional discards not in middle of run of discards.  */
+	  if (discards[i] == 2)
+	    discards[i] = 0;
+	  else if (discards[i] != 0)
+	    {
+	      /* We have found a nonprovisional discard.  */
+	      register lin j;
+	      lin length;
+	      lin provisional = 0;
+
+	      /* Find end of this run of discardable lines.
+		 Count how many are provisionally discardable.  */
+	      for (j = i; j < end; j++)
+		{
+		  if (discards[j] == 0)
+		    break;
+		  if (discards[j] == 2)
+		    ++provisional;
+		}
+
+	      /* Cancel provisional discards at end, and shrink the run.  */
+	      while (j > i && discards[j - 1] == 2)
+		discards[--j] = 0, --provisional;
+
+	      /* Now we have the length of a run of discardable lines
+		 whose first and last are not provisional.  */
+	      length = j - i;
+
+	      /* If 1/4 of the lines in the run are provisional,
+		 cancel discarding of all provisional lines in the run.  */
+	      if (provisional * 4 > length)
+		{
+		  while (j > i)
+		    if (discards[--j] == 2)
+		      discards[j] = 0;
+		}
+	      else
+		{
+		  register lin consec;
+		  lin minimum = 1;
+		  lin tem = length >> 2;
+
+		  /* MINIMUM is approximate square root of LENGTH/4.
+		     A subrun of two or more provisionals can stand
+		     when LENGTH is at least 16.
+		     A subrun of 4 or more can stand when LENGTH >= 64.  */
+		  while (0 < (tem >>= 2))
+		    minimum <<= 1;
+		  minimum++;
+
+		  /* Cancel any subrun of MINIMUM or more provisionals
+		     within the larger run.  */
+		  for (j = 0, consec = 0; j < length; j++)
+		    if (discards[i + j] != 2)
+		      consec = 0;
+		    else if (minimum == ++consec)
+		      /* Back up to start of subrun, to cancel it all.  */
+		      j -= consec;
+		    else if (minimum < consec)
+		      discards[i + j] = 0;
+
+		  /* Scan from beginning of run
+		     until we find 3 or more nonprovisionals in a row
+		     or until the first nonprovisional at least 8 lines in.
+		     Until that point, cancel any provisionals.  */
+		  for (j = 0, consec = 0; j < length; j++)
+		    {
+		      if (j >= 8 && discards[i + j] == 1)
+			break;
+		      if (discards[i + j] == 2)
+			consec = 0, discards[i + j] = 0;
+		      else if (discards[i + j] == 0)
+			consec = 0;
+		      else
+			consec++;
+		      if (consec == 3)
+			break;
+		    }
+
+		  /* I advances to the last line of the run.  */
+		  i += length - 1;
+
+		  /* Same thing, from end.  */
+		  for (j = 0, consec = 0; j < length; j++)
+		    {
+		      if (j >= 8 && discards[i - j] == 1)
+			break;
+		      if (discards[i - j] == 2)
+			consec = 0, discards[i - j] = 0;
+		      else if (discards[i - j] == 0)
+			consec = 0;
+		      else
+			consec++;
+		      if (consec == 3)
+			break;
+		    }
+		}
+	    }
+	}
+    }
+
+  /* Actually discard the lines. */
+  for (f = 0; f < 2; f++)
+    {
+      char *discards = discarded[f];
+      lin end = filevec[f].buffered_lines;
+      lin j = 0;
+      for (i = 0; i < end; ++i)
+	if (minimal || discards[i] == 0)
+	  {
+	    filevec[f].undiscarded[j] = filevec[f].equivs[i];
+	    filevec[f].realindexes[j++] = i;
+	  }
+	else
+	  filevec[f].changed[i] = 1;
+      filevec[f].nondiscarded_lines = j;
+    }
+
+  free (discarded[0]);
+  free (equiv_count[0]);
+}
+
+/* Adjust inserts/deletes of identical lines to join changes
+   as much as possible.
+
+   We do something when a run of changed lines include a
+   line at one end and have an excluded, identical line at the other.
+   We are free to choose which identical line is included.
+   `compareseq' usually chooses the one at the beginning,
+   but usually it is cleaner to consider the following identical line
+   to be the "change".  */
+
+static void
+shift_boundaries (struct file_data filevec[])
+{
+  int f;
+
+  for (f = 0; f < 2; f++)
+    {
+      char *changed = filevec[f].changed;
+      char *other_changed = filevec[1 - f].changed;
+      lin const *equivs = filevec[f].equivs;
+      lin i = 0;
+      lin j = 0;
+      lin i_end = filevec[f].buffered_lines;
+
+      while (1)
+	{
+	  lin runlength, start, corresponding;
+
+	  /* Scan forwards to find beginning of another run of changes.
+	     Also keep track of the corresponding point in the other file.  */
+
+	  while (i < i_end && !changed[i])
+	    {
+	      while (other_changed[j++])
+		continue;
+	      i++;
+	    }
+
+	  if (i == i_end)
+	    break;
+
+	  start = i;
+
+	  /* Find the end of this run of changes.  */
+
+	  while (changed[++i])
+	    continue;
+	  while (other_changed[j])
+	    j++;
+
+	  do
+	    {
+	      /* Record the length of this run of changes, so that
+		 we can later determine whether the run has grown.  */
+	      runlength = i - start;
+
+	      /* Move the changed region back, so long as the
+		 previous unchanged line matches the last changed one.
+		 This merges with previous changed regions.  */
+
+	      while (start && equivs[start - 1] == equivs[i - 1])
+		{
+		  changed[--start] = 1;
+		  changed[--i] = 0;
+		  while (changed[start - 1])
+		    start--;
+		  while (other_changed[--j])
+		    continue;
+		}
+
+	      /* Set CORRESPONDING to the end of the changed run, at the last
+		 point where it corresponds to a changed run in the other file.
+		 CORRESPONDING == I_END means no such point has been found.  */
+	      corresponding = other_changed[j - 1] ? i : i_end;
+
+	      /* Move the changed region forward, so long as the
+		 first changed line matches the following unchanged one.
+		 This merges with following changed regions.
+		 Do this second, so that if there are no merges,
+		 the changed region is moved forward as far as possible.  */
+
+	      while (i != i_end && equivs[start] == equivs[i])
+		{
+		  changed[start++] = 0;
+		  changed[i++] = 1;
+		  while (changed[i])
+		    i++;
+		  while (other_changed[++j])
+		    corresponding = i;
+		}
+	    }
+	  while (runlength != i - start);
+
+	  /* If possible, move the fully-merged run of changes
+	     back to a corresponding run in the other file.  */
+
+	  while (corresponding < i)
+	    {
+	      changed[--start] = 1;
+	      changed[--i] = 0;
+	      while (other_changed[--j])
+		continue;
+	    }
+	}
+    }
+}
+
+/* Cons an additional entry onto the front of an edit script OLD.
+   LINE0 and LINE1 are the first affected lines in the two files (origin 0).
+   DELETED is the number of lines deleted here from file 0.
+   INSERTED is the number of lines inserted here in file 1.
+
+   If DELETED is 0 then LINE0 is the number of the line before
+   which the insertion was done; vice versa for INSERTED and LINE1.  */
+
+static struct change *
+add_change (lin line0, lin line1, lin deleted, lin inserted,
+	    struct change *old)
+{
+  struct change *new = xmalloc (sizeof *new);
+
+  new->line0 = line0;
+  new->line1 = line1;
+  new->inserted = inserted;
+  new->deleted = deleted;
+  new->link = old;
+  return new;
+}
+
+/* Scan the tables of which lines are inserted and deleted,
+   producing an edit script in reverse order.  */
+
+static struct change *
+build_reverse_script (struct file_data const filevec[])
+{
+  struct change *script = 0;
+  char *changed0 = filevec[0].changed;
+  char *changed1 = filevec[1].changed;
+  lin len0 = filevec[0].buffered_lines;
+  lin len1 = filevec[1].buffered_lines;
+
+  /* Note that changedN[lenN] does exist, and is 0.  */
+
+  lin i0 = 0, i1 = 0;
+
+  while (i0 < len0 || i1 < len1)
+    {
+      if (changed0[i0] | changed1[i1])
+	{
+	  lin line0 = i0, line1 = i1;
+
+	  /* Find # lines changed here in each file.  */
+	  while (changed0[i0]) ++i0;
+	  while (changed1[i1]) ++i1;
+
+	  /* Record this change.  */
+	  script = add_change (line0, line1, i0 - line0, i1 - line1, script);
+	}
+
+      /* We have reached lines in the two files that match each other.  */
+      i0++, i1++;
+    }
+
+  return script;
+}
+
+/* Scan the tables of which lines are inserted and deleted,
+   producing an edit script in forward order.  */
+
+static struct change *
+build_script (struct file_data const filevec[])
+{
+  struct change *script = 0;
+  char *changed0 = filevec[0].changed;
+  char *changed1 = filevec[1].changed;
+  lin i0 = filevec[0].buffered_lines, i1 = filevec[1].buffered_lines;
+
+  /* Note that changedN[-1] does exist, and is 0.  */
+
+  while (i0 >= 0 || i1 >= 0)
+    {
+      if (changed0[i0 - 1] | changed1[i1 - 1])
+	{
+	  lin line0 = i0, line1 = i1;
+
+	  /* Find # lines changed here in each file.  */
+	  while (changed0[i0 - 1]) --i0;
+	  while (changed1[i1 - 1]) --i1;
+
+	  /* Record this change.  */
+	  script = add_change (i0, i1, line0 - i0, line1 - i1, script);
+	}
+
+      /* We have reached lines in the two files that match each other.  */
+      i0--, i1--;
+    }
+
+  return script;
+}
+
+/* If CHANGES, briefly report that two files differed.
+   Return 2 if trouble, CHANGES otherwise.  */
+static int
+briefly_report (int changes, struct file_data const filevec[])
+{
+  if (changes)
+    {
+      char const *label0 = file_label[0] ? file_label[0] : filevec[0].name;
+      char const *label1 = file_label[1] ? file_label[1] : filevec[1].name;
+
+      if (brief)
+	message ("Files %s and %s differ\n", label0, label1);
+      else
+	{
+	  message ("Binary files %s and %s differ\n", label0, label1);
+	  changes = 2;
+	}
+    }
+
+  return changes;
+}
+
+/* Report the differences of two files.  */
+int
+diff_2_files (struct comparison *cmp)
+{
+  int f;
+  struct change *e, *p;
+  struct change *script;
+  int changes;
+
+
+  /* If we have detected that either file is binary,
+     compare the two files as binary.  This can happen
+     only when the first chunk is read.
+     Also, --brief without any --ignore-* options means
+     we can speed things up by treating the files as binary.  */
+
+  if (read_files (cmp->file, files_can_be_treated_as_binary))
+    {
+      /* Files with different lengths must be different.  */
+      if (cmp->file[0].stat.st_size != cmp->file[1].stat.st_size
+	  && (cmp->file[0].desc < 0 || S_ISREG (cmp->file[0].stat.st_mode))
+	  && (cmp->file[1].desc < 0 || S_ISREG (cmp->file[1].stat.st_mode)))
+	changes = 1;
+
+      /* Standard input equals itself.  */
+      else if (cmp->file[0].desc == cmp->file[1].desc)
+	changes = 0;
+
+      else
+	/* Scan both files, a buffer at a time, looking for a difference.  */
+	{
+	  /* Allocate same-sized buffers for both files.  */
+	  size_t lcm_max = PTRDIFF_MAX - 1;
+	  size_t buffer_size =
+	    buffer_lcm (sizeof (word),
+			buffer_lcm (STAT_BLOCKSIZE (cmp->file[0].stat),
+				    STAT_BLOCKSIZE (cmp->file[1].stat),
+				    lcm_max),
+			lcm_max);
+	  for (f = 0; f < 2; f++)
+	    cmp->file[f].buffer = xrealloc (cmp->file[f].buffer, buffer_size);
+
+	  for (;; cmp->file[0].buffered = cmp->file[1].buffered = 0)
+	    {
+	      /* Read a buffer's worth from both files.  */
+	      for (f = 0; f < 2; f++)
+		if (0 <= cmp->file[f].desc)
+		  file_block_read (&cmp->file[f],
+				   buffer_size - cmp->file[f].buffered);
+
+	      /* If the buffers differ, the files differ.  */
+	      if (cmp->file[0].buffered != cmp->file[1].buffered
+		  || memcmp (cmp->file[0].buffer,
+			     cmp->file[1].buffer,
+			     cmp->file[0].buffered))
+		{
+		  changes = 1;
+		  break;
+		}
+
+	      /* If we reach end of file, the files are the same.  */
+	      if (cmp->file[0].buffered != buffer_size)
+		{
+		  changes = 0;
+		  break;
+		}
+	    }
+	}
+
+      changes = briefly_report (changes, cmp->file);
+    }
+  else
+    {
+      struct context ctxt;
+      lin diags;
+      lin too_expensive;
+
+      /* Allocate vectors for the results of comparison:
+	 a flag for each line of each file, saying whether that line
+	 is an insertion or deletion.
+	 Allocate an extra element, always 0, at each end of each vector.  */
+
+      size_t s = cmp->file[0].buffered_lines + cmp->file[1].buffered_lines + 4;
+      char *flag_space = zalloc (s);
+      cmp->file[0].changed = flag_space + 1;
+      cmp->file[1].changed = flag_space + cmp->file[0].buffered_lines + 3;
+
+      /* Some lines are obviously insertions or deletions
+	 because they don't match anything.  Detect them now, and
+	 avoid even thinking about them in the main comparison algorithm.  */
+
+      discard_confusing_lines (cmp->file);
+
+      /* Now do the main comparison algorithm, considering just the
+	 undiscarded lines.  */
+
+      ctxt.xvec = cmp->file[0].undiscarded;
+      ctxt.yvec = cmp->file[1].undiscarded;
+      diags = (cmp->file[0].nondiscarded_lines
+	       + cmp->file[1].nondiscarded_lines + 3);
+      ctxt.fdiag = xmalloc (diags * (2 * sizeof *ctxt.fdiag));
+      ctxt.bdiag = ctxt.fdiag + diags;
+      ctxt.fdiag += cmp->file[1].nondiscarded_lines + 1;
+      ctxt.bdiag += cmp->file[1].nondiscarded_lines + 1;
+
+      ctxt.heuristic = speed_large_files;
+
+      /* Set TOO_EXPENSIVE to be approximate square root of input size,
+	 bounded below by 256.  */
+      too_expensive = 1;
+      for (;  diags != 0;  diags >>= 2)
+	too_expensive <<= 1;
+      ctxt.too_expensive = MAX (256, too_expensive);
+
+      files[0] = cmp->file[0];
+      files[1] = cmp->file[1];
+
+      compareseq (0, cmp->file[0].nondiscarded_lines,
+		  0, cmp->file[1].nondiscarded_lines, minimal, &ctxt);
+
+      free (ctxt.fdiag - (cmp->file[1].nondiscarded_lines + 1));
+
+      /* Modify the results slightly to make them prettier
+	 in cases where that can validly be done.  */
+
+      shift_boundaries (cmp->file);
+
+      /* Get the results of comparison in the form of a chain
+	 of `struct change's -- an edit script.  */
+
+      if (output_style == OUTPUT_ED)
+	script = build_reverse_script (cmp->file);
+      else
+	script = build_script (cmp->file);
+
+      /* Set CHANGES if we had any diffs.
+	 If some changes are ignored, we must scan the script to decide.  */
+      if (ignore_blank_lines || ignore_regexp.fastmap)
+	{
+	  struct change *next = script;
+	  changes = 0;
+
+	  while (next && changes == 0)
+	    {
+	      struct change *this, *end;
+	      lin first0, last0, first1, last1;
+
+	      /* Find a set of changes that belong together.  */
+	      this = next;
+	      end = find_change (next);
+
+	      /* Disconnect them from the rest of the changes, making them
+		 a hunk, and remember the rest for next iteration.  */
+	      next = end->link;
+	      end->link = 0;
+
+	      /* Determine whether this hunk is really a difference.  */
+	      if (analyze_hunk (this, &first0, &last0, &first1, &last1))
+		changes = 1;
+
+	      /* Reconnect the script so it will all be freed properly.  */
+	      end->link = next;
+	    }
+	}
+      else
+	changes = (script != 0);
+
+      if (brief)
+	changes = briefly_report (changes, cmp->file);
+      else
+	{
+	  if (changes || !no_diff_means_no_output)
+	    {
+	      /* Record info for starting up output,
+		 to be used if and when we have some output to print.  */
+	      setup_output (file_label[0] ? file_label[0] : cmp->file[0].name,
+			    file_label[1] ? file_label[1] : cmp->file[1].name,
+			    cmp->parent != 0);
+
+	      switch (output_style)
+		{
+		case OUTPUT_CONTEXT:
+		  print_context_script (script, false);
+		  break;
+
+		case OUTPUT_UNIFIED:
+		  print_context_script (script, true);
+		  break;
+
+		case OUTPUT_ED:
+		  print_ed_script (script);
+		  break;
+
+		case OUTPUT_FORWARD_ED:
+		  pr_forward_ed_script (script);
+		  break;
+
+		case OUTPUT_RCS:
+		  print_rcs_script (script);
+		  break;
+
+		case OUTPUT_NORMAL:
+		  print_normal_script (script);
+		  break;
+
+		case OUTPUT_IFDEF:
+		  print_ifdef_script (script);
+		  break;
+
+		case OUTPUT_SDIFF:
+		  print_sdiff_script (script);
+		  break;
+
+		default:
+		  abort ();
+		}
+
+	      finish_output ();
+	    }
+	}
+
+      free (cmp->file[0].undiscarded);
+
+      free (flag_space);
+
+      for (f = 0; f < 2; f++)
+	{
+	  free (cmp->file[f].equivs);
+	  free (cmp->file[f].linbuf + cmp->file[f].linbuf_base);
+	}
+
+      for (e = script; e; e = p)
+	{
+	  p = e->link;
+	  free (e);
+	}
+
+      if (! ROBUST_OUTPUT_STYLE (output_style))
+	for (f = 0; f < 2; ++f)
+	  if (cmp->file[f].missing_newline)
+	    {
+	      error (0, 0, "%s: %s\n",
+		     file_label[f] ? file_label[f] : cmp->file[f].name,
+		     _("No newline at end of file"));
+	      changes = 2;
+	    }
+    }
+
+  if (cmp->file[0].buffer != cmp->file[1].buffer)
+    free (cmp->file[0].buffer);
+  free (cmp->file[1].buffer);
+
+  return changes;
+}
diff --git a/src/cmp.c b/src/cmp.c
new file mode 100644
index 0000000..adf1cf9
--- /dev/null
+++ b/src/cmp.c
@@ -0,0 +1,691 @@
+/* cmp - compare two files byte by byte
+
+   Copyright (C) 1990-1996, 1998, 2001-2002, 2004, 2006-2007, 2009-2011 Free
+   Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "system.h"
+#include "paths.h"
+
+#include <stdio.h>
+
+#include <c-stack.h>
+#include <cmpbuf.h>
+#include <error.h>
+#include <exitfail.h>
+#include <file-type.h>
+#include <getopt.h>
+#include <hard-locale.h>
+#include <inttostr.h>
+#include <progname.h>
+#include <unlocked-io.h>
+#include <version-etc.h>
+#include <xalloc.h>
+#include <xfreopen.h>
+#include <xstrtol.h>
+
+/* The official name of this program (e.g., no `g' prefix).  */
+#define PROGRAM_NAME "cmp"
+
+#define AUTHORS \
+  proper_name_utf8 ("Torbjorn Granlund", "Torbj\303\266rn Granlund"), \
+  proper_name ("David MacKenzie")
+
+#if defined LC_MESSAGES && ENABLE_NLS
+# define hard_locale_LC_MESSAGES hard_locale (LC_MESSAGES)
+#else
+# define hard_locale_LC_MESSAGES 0
+#endif
+
+static int cmp (void);
+static off_t file_position (int);
+static size_t block_compare (word const *, word const *);
+static size_t block_compare_and_count (word const *, word const *, off_t *);
+static void sprintc (char *, unsigned char);
+
+/* Filenames of the compared files.  */
+static char const *file[2];
+
+/* File descriptors of the files.  */
+static int file_desc[2];
+
+/* Status of the files.  */
+static struct stat stat_buf[2];
+
+/* Read buffers for the files.  */
+static word *buffer[2];
+
+/* Optimal block size for the files.  */
+static size_t buf_size;
+
+/* Initial prefix to ignore for each file.  */
+static off_t ignore_initial[2];
+
+/* Number of bytes to compare.  */
+static uintmax_t bytes = UINTMAX_MAX;
+
+/* Output format.  */
+static enum comparison_type
+  {
+    type_first_diff,	/* Print the first difference.  */
+    type_all_diffs,	/* Print all differences.  */
+    type_no_stdout,	/* Do not output to stdout; only stderr.  */
+    type_status		/* Exit status only.  */
+  } comparison_type;
+
+/* If nonzero, print values of bytes quoted like cat -t does. */
+static bool opt_print_bytes;
+
+/* Values for long options that do not have single-letter equivalents.  */
+enum
+{
+  HELP_OPTION = CHAR_MAX + 1
+};
+
+static struct option const long_options[] =
+{
+  {"print-bytes", 0, 0, 'b'},
+  {"print-chars", 0, 0, 'c'}, /* obsolescent as of diffutils 2.7.3 */
+  {"ignore-initial", 1, 0, 'i'},
+  {"verbose", 0, 0, 'l'},
+  {"bytes", 1, 0, 'n'},
+  {"silent", 0, 0, 's'},
+  {"quiet", 0, 0, 's'},
+  {"version", 0, 0, 'v'},
+  {"help", 0, 0, HELP_OPTION},
+  {0, 0, 0, 0}
+};
+
+static void try_help (char const *, char const *) __attribute__((noreturn));
+static void
+try_help (char const *reason_msgid, char const *operand)
+{
+  if (reason_msgid)
+    error (0, 0, _(reason_msgid), operand);
+  error (EXIT_TROUBLE, 0,
+	 _("Try `%s --help' for more information."), program_name);
+  abort ();
+}
+
+static char const valid_suffixes[] = "kKMGTPEZY0";
+
+/* Update ignore_initial[F] according to the result of parsing an
+   *operand ARGPTR of --ignore-initial, updating *ARGPTR to point
+   *after the operand.  If DELIMITER is nonzero, the operand may be
+   *followed by DELIMITER; otherwise it must be null-terminated.  */
+static void
+specify_ignore_initial (int f, char **argptr, char delimiter)
+{
+  uintmax_t val;
+  char const *arg = *argptr;
+  strtol_error e = xstrtoumax (arg, argptr, 0, &val, valid_suffixes);
+  if (! (e == LONGINT_OK
+	 || (e == LONGINT_INVALID_SUFFIX_CHAR && **argptr == delimiter))
+      || TYPE_MAXIMUM (off_t) < val)
+    try_help ("invalid --ignore-initial value `%s'", arg);
+  if (ignore_initial[f] < val)
+    ignore_initial[f] = val;
+}
+
+/* Specify the output format.  */
+static void
+specify_comparison_type (enum comparison_type t)
+{
+  if (comparison_type && comparison_type != t)
+    try_help ("options -l and -s are incompatible", 0);
+  comparison_type = t;
+}
+
+static void
+check_stdout (void)
+{
+  if (ferror (stdout))
+    error (EXIT_TROUBLE, 0, "%s", _("write failed"));
+  else if (fclose (stdout) != 0)
+    error (EXIT_TROUBLE, errno, "%s", _("standard output"));
+}
+
+static char const * const option_help_msgid[] = {
+  N_("-b, --print-bytes          print differing bytes"),
+  N_("-i, --ignore-initial=SKIP         skip first SKIP bytes of both inputs"),
+  N_("-i, --ignore-initial=SKIP1:SKIP2  skip first SKIP1 bytes of FILE1 and\n"
+     "                                      first SKIP2 bytes of FILE2"),
+  N_("-l, --verbose              output byte numbers and differing byte values"),
+  N_("-n, --bytes=LIMIT          compare at most LIMIT bytes"),
+  N_("-s, --quiet, --silent      suppress all normal output"),
+  N_("    --help                 display this help and exit"),
+  N_("-v, --version              output version information and exit"),
+  0
+};
+
+static void
+usage (void)
+{
+  char const * const *p;
+
+  printf (_("Usage: %s [OPTION]... FILE1 [FILE2 [SKIP1 [SKIP2]]]\n"),
+	  program_name);
+  printf ("%s\n", _("Compare two files byte by byte."));
+  printf ("\n%s\n\n",
+_("The optional SKIP1 and SKIP2 specify the number of bytes to skip\n"
+  "at the beginning of each file (zero by default)."));
+
+  fputs (_("\
+Mandatory arguments to long options are mandatory for short options too.\n\
+"), stdout);
+  for (p = option_help_msgid;  *p;  p++)
+    printf ("  %s\n", _(*p));
+  printf ("\n%s\n\n%s\n%s\n",
+	  _("SKIP values may be followed by the following multiplicative suffixes:\n\
+kB 1000, K 1024, MB 1,000,000, M 1,048,576,\n\
+GB 1,000,000,000, G 1,073,741,824, and so on for T, P, E, Z, Y."),
+	  _("If a FILE is `-' or missing, read standard input."),
+	  _("Exit status is 0 if inputs are the same, 1 if different, 2 if trouble."));
+  emit_bug_reporting_address ();
+}
+
+int
+main (int argc, char **argv)
+{
+  int c, f, exit_status;
+  size_t words_per_buffer;
+
+  exit_failure = EXIT_TROUBLE;
+  initialize_main (&argc, &argv);
+  set_program_name (argv[0]);
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+  c_stack_action (0);
+
+  /* Parse command line options.  */
+
+  while ((c = getopt_long (argc, argv, "bci:ln:sv", long_options, 0))
+	 != -1)
+    switch (c)
+      {
+      case 'b':
+      case 'c': /* 'c' is obsolescent as of diffutils 2.7.3 */
+	opt_print_bytes = true;
+	break;
+
+      case 'i':
+	specify_ignore_initial (0, &optarg, ':');
+	if (*optarg++ == ':')
+	  specify_ignore_initial (1, &optarg, 0);
+	else if (ignore_initial[1] < ignore_initial[0])
+	  ignore_initial[1] = ignore_initial[0];
+	break;
+
+      case 'l':
+	specify_comparison_type (type_all_diffs);
+	break;
+
+      case 'n':
+	{
+	  uintmax_t n;
+	  if (xstrtoumax (optarg, 0, 0, &n, valid_suffixes) != LONGINT_OK)
+	    try_help ("invalid --bytes value `%s'", optarg);
+	  if (n < bytes)
+	    bytes = n;
+	}
+	break;
+
+      case 's':
+	specify_comparison_type (type_status);
+	break;
+
+      case 'v':
+	version_etc (stdout, PROGRAM_NAME, PACKAGE_NAME, Version,
+		     AUTHORS, (char *) NULL);
+	check_stdout ();
+	return EXIT_SUCCESS;
+
+      case HELP_OPTION:
+	usage ();
+	check_stdout ();
+	return EXIT_SUCCESS;
+
+      default:
+	try_help (0, 0);
+      }
+
+  if (optind == argc)
+    try_help ("missing operand after `%s'", argv[argc - 1]);
+
+  file[0] = argv[optind++];
+  file[1] = optind < argc ? argv[optind++] : "-";
+
+  for (f = 0; f < 2 && optind < argc; f++)
+    {
+      char *arg = argv[optind++];
+      specify_ignore_initial (f, &arg, 0);
+    }
+
+  if (optind < argc)
+    try_help ("extra operand `%s'", argv[optind]);
+
+  for (f = 0; f < 2; f++)
+    {
+      /* If file[1] is "-", treat it first; this avoids a misdiagnostic if
+	 stdin is closed and opening file[0] yields file descriptor 0.  */
+      int f1 = f ^ (STREQ (file[1], "-"));
+
+      /* Two files with the same name and offset are identical.
+	 But wait until we open the file once, for proper diagnostics.  */
+      if (f && ignore_initial[0] == ignore_initial[1]
+	  && file_name_cmp (file[0], file[1]) == 0)
+	return EXIT_SUCCESS;
+
+      if (STREQ (file[f1], "-"))
+	{
+	  file_desc[f1] = STDIN_FILENO;
+	  if (O_BINARY && ! isatty (STDIN_FILENO))
+	    xfreopen (NULL, "rb", stdin);
+	}
+      else
+	file_desc[f1] = open (file[f1], O_RDONLY | O_BINARY, 0);
+
+      if (file_desc[f1] < 0 || fstat (file_desc[f1], stat_buf + f1) != 0)
+	{
+	  if (file_desc[f1] < 0 && comparison_type == type_status)
+	    exit (EXIT_TROUBLE);
+	  else
+	    error (EXIT_TROUBLE, errno, "%s", file[f1]);
+	}
+    }
+
+  /* If the files are links to the same inode and have the same file position,
+     they are identical.  */
+
+  if (0 < same_file (&stat_buf[0], &stat_buf[1])
+      && same_file_attributes (&stat_buf[0], &stat_buf[1])
+      && file_position (0) == file_position (1))
+    return EXIT_SUCCESS;
+
+  /* If output is redirected to the null device, we can avoid some of
+     the work.  */
+
+  if (comparison_type != type_status)
+    {
+      struct stat outstat, nullstat;
+
+      if (fstat (STDOUT_FILENO, &outstat) == 0
+	  && stat (NULL_DEVICE, &nullstat) == 0
+	  && 0 < same_file (&outstat, &nullstat))
+	comparison_type = type_no_stdout;
+    }
+
+  /* If only a return code is needed,
+     and if both input descriptors are associated with plain files,
+     conclude that the files differ if they have different sizes
+     and if more bytes will be compared than are in the smaller file.  */
+
+  if (comparison_type == type_status
+      && S_ISREG (stat_buf[0].st_mode)
+      && S_ISREG (stat_buf[1].st_mode))
+    {
+      off_t s0 = stat_buf[0].st_size - file_position (0);
+      off_t s1 = stat_buf[1].st_size - file_position (1);
+      if (s0 < 0)
+	s0 = 0;
+      if (s1 < 0)
+	s1 = 0;
+      if (s0 != s1 && MIN (s0, s1) < bytes)
+	exit (EXIT_FAILURE);
+    }
+
+  /* Get the optimal block size of the files.  */
+
+  buf_size = buffer_lcm (STAT_BLOCKSIZE (stat_buf[0]),
+			 STAT_BLOCKSIZE (stat_buf[1]),
+			 PTRDIFF_MAX - sizeof (word));
+
+  /* Allocate word-aligned buffers, with space for sentinels at the end.  */
+
+  words_per_buffer = (buf_size + 2 * sizeof (word) - 1) / sizeof (word);
+  buffer[0] = xmalloc (2 * sizeof (word) * words_per_buffer);
+  buffer[1] = buffer[0] + words_per_buffer;
+
+  exit_status = cmp ();
+
+  for (f = 0; f < 2; f++)
+    if (close (file_desc[f]) != 0)
+      error (EXIT_TROUBLE, errno, "%s", file[f]);
+  if (exit_status != EXIT_SUCCESS && comparison_type < type_no_stdout)
+    check_stdout ();
+  exit (exit_status);
+  return exit_status;
+}
+
+/* Compare the two files already open on `file_desc[0]' and `file_desc[1]',
+   using `buffer[0]' and `buffer[1]'.
+   Return EXIT_SUCCESS if identical, EXIT_FAILURE if different,
+   >1 if error.  */
+
+static int
+cmp (void)
+{
+  off_t line_number = 1;	/* Line number (1...) of difference. */
+  off_t byte_number = 1;	/* Byte number (1...) of difference. */
+  uintmax_t remaining = bytes;	/* Remaining number of bytes to compare.  */
+  size_t read0, read1;		/* Number of bytes read from each file. */
+  size_t first_diff;		/* Offset (0...) in buffers of 1st diff. */
+  size_t smaller;		/* The lesser of `read0' and `read1'. */
+  word *buffer0 = buffer[0];
+  word *buffer1 = buffer[1];
+  char *buf0 = (char *) buffer0;
+  char *buf1 = (char *) buffer1;
+  int differing = 0;
+  int f;
+  int offset_width IF_LINT (= 0);
+
+  if (comparison_type == type_all_diffs)
+    {
+      off_t byte_number_max = MIN (bytes, TYPE_MAXIMUM (off_t));
+
+      for (f = 0; f < 2; f++)
+	if (S_ISREG (stat_buf[f].st_mode))
+	  {
+	    off_t file_bytes = stat_buf[f].st_size - file_position (f);
+	    if (file_bytes < byte_number_max)
+	      byte_number_max = file_bytes;
+	  }
+
+      for (offset_width = 1; (byte_number_max /= 10) != 0; offset_width++)
+	continue;
+    }
+
+  for (f = 0; f < 2; f++)
+    {
+      off_t ig = ignore_initial[f];
+      if (ig && file_position (f) == -1)
+	{
+	  /* lseek failed; read and discard the ignored initial prefix.  */
+	  do
+	    {
+	      size_t bytes_to_read = MIN (ig, buf_size);
+	      size_t r = block_read (file_desc[f], buf0, bytes_to_read);
+	      if (r != bytes_to_read)
+		{
+		  if (r == SIZE_MAX)
+		    error (EXIT_TROUBLE, errno, "%s", file[f]);
+		  break;
+		}
+	      ig -= r;
+	    }
+	  while (ig);
+	}
+    }
+
+  do
+    {
+      size_t bytes_to_read = buf_size;
+
+      if (remaining != UINTMAX_MAX)
+	{
+	  if (remaining < bytes_to_read)
+	    bytes_to_read = remaining;
+	  remaining -= bytes_to_read;
+	}
+
+      read0 = block_read (file_desc[0], buf0, bytes_to_read);
+      if (read0 == SIZE_MAX)
+	error (EXIT_TROUBLE, errno, "%s", file[0]);
+      read1 = block_read (file_desc[1], buf1, bytes_to_read);
+      if (read1 == SIZE_MAX)
+	error (EXIT_TROUBLE, errno, "%s", file[1]);
+
+      /* Insert sentinels for the block compare.  */
+
+      buf0[read0] = ~buf1[read0];
+      buf1[read1] = ~buf0[read1];
+
+      /* If the line number should be written for differing files,
+	 compare the blocks and count the number of newlines
+	 simultaneously.  */
+      first_diff = (comparison_type == type_first_diff
+		    ? block_compare_and_count (buffer0, buffer1, &line_number)
+		    : block_compare (buffer0, buffer1));
+
+      byte_number += first_diff;
+      smaller = MIN (read0, read1);
+
+      if (first_diff < smaller)
+	{
+	  switch (comparison_type)
+	    {
+	    case type_first_diff:
+	      {
+		char byte_buf[INT_BUFSIZE_BOUND (off_t)];
+		char line_buf[INT_BUFSIZE_BOUND (off_t)];
+		char const *byte_num = offtostr (byte_number, byte_buf);
+		char const *line_num = offtostr (line_number, line_buf);
+		if (!opt_print_bytes)
+		  {
+		    /* See POSIX 1003.1-2001 for this format.  This
+		       message is used only in the POSIX locale, so it
+		       need not be translated.  */
+		    static char const char_message[] =
+		      "%s %s differ: char %s, line %s\n";
+
+		    /* The POSIX rationale recommends using the word
+		       "byte" outside the POSIX locale.  Some gettext
+		       implementations translate even in the POSIX
+		       locale if certain other environment variables
+		       are set, so use "byte" if a translation is
+		       available, or if outside the POSIX locale.  */
+		    static char const byte_msgid[] =
+		      N_("%s %s differ: byte %s, line %s\n");
+		    char const *byte_message = _(byte_msgid);
+		    bool use_byte_message = (byte_message != byte_msgid
+					     || hard_locale_LC_MESSAGES);
+
+		    printf (use_byte_message ? byte_message : char_message,
+			    file[0], file[1], byte_num, line_num);
+		  }
+		else
+		  {
+		    unsigned char c0 = buf0[first_diff];
+		    unsigned char c1 = buf1[first_diff];
+		    char s0[5];
+		    char s1[5];
+		    sprintc (s0, c0);
+		    sprintc (s1, c1);
+		    printf (_("%s %s differ: byte %s, line %s is %3o %s %3o %s\n"),
+			    file[0], file[1], byte_num, line_num,
+			    c0, s0, c1, s1);
+		}
+	      }
+	      /* Fall through.  */
+	    case type_status:
+	      return EXIT_FAILURE;
+
+	    case type_all_diffs:
+	      do
+		{
+		  unsigned char c0 = buf0[first_diff];
+		  unsigned char c1 = buf1[first_diff];
+		  if (c0 != c1)
+		    {
+		      char byte_buf[INT_BUFSIZE_BOUND (off_t)];
+		      char const *byte_num = offtostr (byte_number, byte_buf);
+		      if (!opt_print_bytes)
+			{
+			  /* See POSIX 1003.1-2001 for this format.  */
+			  printf ("%*s %3o %3o\n",
+				  offset_width, byte_num, c0, c1);
+			}
+		      else
+			{
+			  char s0[5];
+			  char s1[5];
+			  sprintc (s0, c0);
+			  sprintc (s1, c1);
+			  printf ("%*s %3o %-4s %3o %s\n",
+				  offset_width, byte_num, c0, s0, c1, s1);
+			}
+		    }
+		  byte_number++;
+		  first_diff++;
+		}
+	      while (first_diff < smaller);
+	      differing = -1;
+	      break;
+
+	    case type_no_stdout:
+	      differing = 1;
+	      break;
+	    }
+	}
+
+      if (read0 != read1)
+	{
+	  if (differing <= 0 && comparison_type != type_status)
+	    {
+	      /* See POSIX 1003.1-2001 for this format.  */
+	      fprintf (stderr, _("cmp: EOF on %s\n"), file[read1 < read0]);
+	    }
+
+	  return EXIT_FAILURE;
+	}
+    }
+  while (differing <= 0 && read0 == buf_size);
+
+  return differing == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+
+/* Compare two blocks of memory P0 and P1 until they differ,
+   and count the number of '\n' occurrences in the common
+   part of P0 and P1.
+   If the blocks are not guaranteed to be different, put sentinels at the ends
+   of the blocks before calling this function.
+
+   Return the offset of the first byte that differs.
+   Increment *COUNT by the count of '\n' occurrences.  */
+
+static size_t
+block_compare_and_count (word const *p0, word const *p1, off_t *count)
+{
+  word l;		/* One word from first buffer. */
+  word const *l0, *l1;	/* Pointers into each buffer. */
+  char const *c0, *c1;	/* Pointers for finding exact address. */
+  size_t cnt = 0;	/* Number of '\n' occurrences. */
+  word nnnn;		/* Newline, sizeof (word) times.  */
+  int i;
+
+  nnnn = 0;
+  for (i = 0; i < sizeof nnnn; i++)
+    nnnn = (nnnn << CHAR_BIT) | '\n';
+
+  /* Find the rough position of the first difference by reading words,
+     not bytes.  */
+
+  for (l0 = p0, l1 = p1;  (l = *l0) == *l1;  l0++, l1++)
+    {
+      l ^= nnnn;
+      for (i = 0; i < sizeof l; i++)
+	{
+	  unsigned char uc = l;
+	  cnt += ! uc;
+	  l >>= CHAR_BIT;
+	}
+    }
+
+  /* Find the exact differing position (endianness independent).  */
+
+  for (c0 = (char const *) l0, c1 = (char const *) l1;
+       *c0 == *c1;
+       c0++, c1++)
+    cnt += *c0 == '\n';
+
+  *count += cnt;
+  return c0 - (char const *) p0;
+}
+
+/* Compare two blocks of memory P0 and P1 until they differ.
+   If the blocks are not guaranteed to be different, put sentinels at the ends
+   of the blocks before calling this function.
+
+   Return the offset of the first byte that differs.  */
+
+static size_t
+block_compare (word const *p0, word const *p1)
+{
+  word const *l0, *l1;
+  char const *c0, *c1;
+
+  /* Find the rough position of the first difference by reading words,
+     not bytes.  */
+
+  for (l0 = p0, l1 = p1;  *l0 == *l1;  l0++, l1++)
+    continue;
+
+  /* Find the exact differing position (endianness independent).  */
+
+  for (c0 = (char const *) l0, c1 = (char const *) l1;
+       *c0 == *c1;
+       c0++, c1++)
+    continue;
+
+  return c0 - (char const *) p0;
+}
+
+/* Put into BUF the unsigned char C, making unprintable bytes
+   visible by quoting like cat -t does.  */
+
+static void
+sprintc (char *buf, unsigned char c)
+{
+  if (! isprint (c))
+    {
+      if (c >= 128)
+	{
+	  *buf++ = 'M';
+	  *buf++ = '-';
+	  c -= 128;
+	}
+      if (c < 32)
+	{
+	  *buf++ = '^';
+	  c += 64;
+	}
+      else if (c == 127)
+	{
+	  *buf++ = '^';
+	  c = '?';
+	}
+    }
+
+  *buf++ = c;
+  *buf = 0;
+}
+
+/* Position file F to ignore_initial[F] bytes from its initial position,
+   and yield its new position.  Don't try more than once.  */
+
+static off_t
+file_position (int f)
+{
+  static bool positioned[2];
+  static off_t position[2];
+
+  if (! positioned[f])
+    {
+      positioned[f] = true;
+      position[f] = lseek (file_desc[f], ignore_initial[f], SEEK_CUR);
+    }
+  return position[f];
+}
diff --git a/src/context.c b/src/context.c
new file mode 100644
index 0000000..690506b
--- /dev/null
+++ b/src/context.c
@@ -0,0 +1,492 @@
+/* Context-format output routines for GNU DIFF.
+
+   Copyright (C) 1988-1989, 1991-1995, 1998, 2001-2002, 2004, 2006, 2009-2011
+   Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "diff.h"
+#include "c-ctype.h"
+#include <stat-time.h>
+#include <strftime.h>
+
+static char const *find_function (char const * const *, lin);
+static struct change *find_hunk (struct change *);
+static void mark_ignorable (struct change *);
+static void pr_context_hunk (struct change *);
+static void pr_unidiff_hunk (struct change *);
+
+/* Last place find_function started searching from.  */
+static lin find_function_last_search;
+
+/* The value find_function returned when it started searching there.  */
+static lin find_function_last_match;
+
+/* Print a label for a context diff, with a file name and date or a label.  */
+
+static void
+print_context_label (char const *mark,
+		     struct file_data *inf,
+		     char const *label)
+{
+  if (label)
+    fprintf (outfile, "%s %s\n", mark, label);
+  else
+    {
+      char buf[MAX (INT_STRLEN_BOUND (int) + 32,
+		    INT_STRLEN_BOUND (time_t) + 11)];
+      struct tm const *tm = localtime (&inf->stat.st_mtime);
+      int nsec = get_stat_mtime_ns (&inf->stat);
+      if (! (tm && nstrftime (buf, sizeof buf, time_format, tm, 0, nsec)))
+	{
+	  verify (TYPE_IS_INTEGER (time_t));
+	  if (LONG_MIN <= TYPE_MINIMUM (time_t)
+	      && TYPE_MAXIMUM (time_t) <= LONG_MAX)
+	    {
+	      long int sec = inf->stat.st_mtime;
+	      sprintf (buf, "%ld.%.9d", sec, nsec);
+	    }
+	  else if (TYPE_MAXIMUM (time_t) <= INTMAX_MAX)
+	    {
+	      intmax_t sec = inf->stat.st_mtime;
+	      sprintf (buf, "%"PRIdMAX".%.9d", sec, nsec);
+	    }
+	  else
+	    {
+	      uintmax_t sec = inf->stat.st_mtime;
+	      sprintf (buf, "%"PRIuMAX".%.9d", sec, nsec);
+	    }
+	}
+      fprintf (outfile, "%s %s\t%s\n", mark, inf->name, buf);
+    }
+}
+
+/* Print a header for a context diff, with the file names and dates.  */
+
+void
+print_context_header (struct file_data inf[], bool unidiff)
+{
+  if (unidiff)
+    {
+      print_context_label ("---", &inf[0], file_label[0]);
+      print_context_label ("+++", &inf[1], file_label[1]);
+    }
+  else
+    {
+      print_context_label ("***", &inf[0], file_label[0]);
+      print_context_label ("---", &inf[1], file_label[1]);
+    }
+}
+
+/* Print an edit script in context format.  */
+
+void
+print_context_script (struct change *script, bool unidiff)
+{
+  if (ignore_blank_lines || ignore_regexp.fastmap)
+    mark_ignorable (script);
+  else
+    {
+      struct change *e;
+      for (e = script; e; e = e->link)
+	e->ignore = false;
+    }
+
+  find_function_last_search = - files[0].prefix_lines;
+  find_function_last_match = LIN_MAX;
+
+  if (unidiff)
+    print_script (script, find_hunk, pr_unidiff_hunk);
+  else
+    print_script (script, find_hunk, pr_context_hunk);
+}
+
+/* Print a pair of line numbers with a comma, translated for file FILE.
+   If the second number is not greater, use the first in place of it.
+
+   Args A and B are internal line numbers.
+   We print the translated (real) line numbers.  */
+
+static void
+print_context_number_range (struct file_data const *file, lin a, lin b)
+{
+  long int trans_a, trans_b;
+  translate_range (file, a, b, &trans_a, &trans_b);
+
+  /* We can have B <= A in the case of a range of no lines.
+     In this case, we should print the line number before the range,
+     which is B.
+
+     POSIX 1003.1-2001 requires two line numbers separated by a comma
+     even if the line numbers are the same.  However, this does not
+     match existing practice and is surely an error in the
+     specification.  */
+
+  if (trans_b <= trans_a)
+    fprintf (outfile, "%ld", trans_b);
+  else
+    fprintf (outfile, "%ld,%ld", trans_a, trans_b);
+}
+
+/* Print FUNCTION in a context header.  */
+static void
+print_context_function (FILE *out, char const *function)
+{
+  int i, j;
+  putc (' ', out);
+  for (i = 0; c_isspace ((unsigned char) function[i]) && function[i] != '\n'; i++)
+    continue;
+  for (j = i; j < i + 40 && function[j] != '\n'; j++)
+    continue;
+  while (i < j && c_isspace ((unsigned char) function[j - 1]))
+    j--;
+  fwrite (function + i, sizeof (char), j - i, out);
+}
+
+/* Print a portion of an edit script in context format.
+   HUNK is the beginning of the portion to be printed.
+   The end is marked by a `link' that has been nulled out.
+
+   Prints out lines from both files, and precedes each
+   line with the appropriate flag-character.  */
+
+static void
+pr_context_hunk (struct change *hunk)
+{
+  lin first0, last0, first1, last1, i;
+  char const *prefix;
+  char const *function;
+  FILE *out;
+
+  /* Determine range of line numbers involved in each file.  */
+
+  enum changes changes = analyze_hunk (hunk, &first0, &last0, &first1, &last1);
+  if (! changes)
+    return;
+
+  /* Include a context's width before and after.  */
+
+  i = - files[0].prefix_lines;
+  first0 = MAX (first0 - context, i);
+  first1 = MAX (first1 - context, i);
+  if (last0 < files[0].valid_lines - context)
+    last0 += context;
+  else
+    last0 = files[0].valid_lines - 1;
+  if (last1 < files[1].valid_lines - context)
+    last1 += context;
+  else
+    last1 = files[1].valid_lines - 1;
+
+  /* If desired, find the preceding function definition line in file 0.  */
+  function = NULL;
+  if (function_regexp.fastmap)
+    function = find_function (files[0].linbuf, first0);
+
+  begin_output ();
+  out = outfile;
+
+  fputs ("***************", out);
+
+  if (function)
+    print_context_function (out, function);
+
+  fputs ("\n*** ", out);
+  print_context_number_range (&files[0], first0, last0);
+  fputs (" ****\n", out);
+
+  if (changes & OLD)
+    {
+      struct change *next = hunk;
+
+      for (i = first0; i <= last0; i++)
+	{
+	  /* Skip past changes that apply (in file 0)
+	     only to lines before line I.  */
+
+	  while (next && next->line0 + next->deleted <= i)
+	    next = next->link;
+
+	  /* Compute the marking for line I.  */
+
+	  prefix = " ";
+	  if (next && next->line0 <= i)
+	    /* The change NEXT covers this line.
+	       If lines were inserted here in file 1, this is "changed".
+	       Otherwise it is "deleted".  */
+	    prefix = (next->inserted > 0 ? "!" : "-");
+
+	  print_1_line (prefix, &files[0].linbuf[i]);
+	}
+    }
+
+  fputs ("--- ", out);
+  print_context_number_range (&files[1], first1, last1);
+  fputs (" ----\n", out);
+
+  if (changes & NEW)
+    {
+      struct change *next = hunk;
+
+      for (i = first1; i <= last1; i++)
+	{
+	  /* Skip past changes that apply (in file 1)
+	     only to lines before line I.  */
+
+	  while (next && next->line1 + next->inserted <= i)
+	    next = next->link;
+
+	  /* Compute the marking for line I.  */
+
+	  prefix = " ";
+	  if (next && next->line1 <= i)
+	    /* The change NEXT covers this line.
+	       If lines were deleted here in file 0, this is "changed".
+	       Otherwise it is "inserted".  */
+	    prefix = (next->deleted > 0 ? "!" : "+");
+
+	  print_1_line (prefix, &files[1].linbuf[i]);
+	}
+    }
+}
+
+/* Print a pair of line numbers with a comma, translated for file FILE.
+   If the second number is smaller, use the first in place of it.
+   If the numbers are equal, print just one number.
+
+   Args A and B are internal line numbers.
+   We print the translated (real) line numbers.  */
+
+static void
+print_unidiff_number_range (struct file_data const *file, lin a, lin b)
+{
+  long int trans_a, trans_b;
+  translate_range (file, a, b, &trans_a, &trans_b);
+
+  /* We can have B < A in the case of a range of no lines.
+     In this case, we print the line number before the range,
+     which is B.  It would be more logical to print A, but
+     'patch' expects B in order to detect diffs against empty files.  */
+  if (trans_b <= trans_a)
+    fprintf (outfile, trans_b < trans_a ? "%ld,0" : "%ld", trans_b);
+  else
+    fprintf (outfile, "%ld,%ld", trans_a, trans_b - trans_a + 1);
+}
+
+/* Print a portion of an edit script in unidiff format.
+   HUNK is the beginning of the portion to be printed.
+   The end is marked by a `link' that has been nulled out.
+
+   Prints out lines from both files, and precedes each
+   line with the appropriate flag-character.  */
+
+static void
+pr_unidiff_hunk (struct change *hunk)
+{
+  lin first0, last0, first1, last1;
+  lin i, j, k;
+  struct change *next;
+  char const *function;
+  FILE *out;
+
+  /* Determine range of line numbers involved in each file.  */
+
+  if (! analyze_hunk (hunk, &first0, &last0, &first1, &last1))
+    return;
+
+  /* Include a context's width before and after.  */
+
+  i = - files[0].prefix_lines;
+  first0 = MAX (first0 - context, i);
+  first1 = MAX (first1 - context, i);
+  if (last0 < files[0].valid_lines - context)
+    last0 += context;
+  else
+    last0 = files[0].valid_lines - 1;
+  if (last1 < files[1].valid_lines - context)
+    last1 += context;
+  else
+    last1 = files[1].valid_lines - 1;
+
+  /* If desired, find the preceding function definition line in file 0.  */
+  function = NULL;
+  if (function_regexp.fastmap)
+    function = find_function (files[0].linbuf, first0);
+
+  begin_output ();
+  out = outfile;
+
+  fputs ("@@ -", out);
+  print_unidiff_number_range (&files[0], first0, last0);
+  fputs (" +", out);
+  print_unidiff_number_range (&files[1], first1, last1);
+  fputs (" @@", out);
+
+  if (function)
+    print_context_function (out, function);
+
+  putc ('\n', out);
+
+  next = hunk;
+  i = first0;
+  j = first1;
+
+  while (i <= last0 || j <= last1)
+    {
+
+      /* If the line isn't a difference, output the context from file 0. */
+
+      if (!next || i < next->line0)
+	{
+	  char const *const *line = &files[0].linbuf[i++];
+	  if (! (suppress_blank_empty && **line == '\n'))
+	    putc (initial_tab ? '\t' : ' ', out);
+	  print_1_line (NULL, line);
+	  j++;
+	}
+      else
+	{
+	  /* For each difference, first output the deleted part. */
+
+	  k = next->deleted;
+	  while (k--)
+	    {
+	      char const * const *line = &files[0].linbuf[i++];
+	      putc ('-', out);
+	      if (initial_tab && ! (suppress_blank_empty && **line == '\n'))
+		putc ('\t', out);
+	      print_1_line (NULL, line);
+	    }
+
+	  /* Then output the inserted part. */
+
+	  k = next->inserted;
+	  while (k--)
+	    {
+	      char const * const *line = &files[1].linbuf[j++];
+	      putc ('+', out);
+	      if (initial_tab && ! (suppress_blank_empty && **line == '\n'))
+		putc ('\t', out);
+	      print_1_line (NULL, line);
+	    }
+
+	  /* We're done with this hunk, so on to the next! */
+
+	  next = next->link;
+	}
+    }
+}
+
+/* Scan a (forward-ordered) edit script for the first place that more than
+   2*CONTEXT unchanged lines appear, and return a pointer
+   to the `struct change' for the last change before those lines.  */
+
+static struct change *
+find_hunk (struct change *start)
+{
+  struct change *prev;
+  lin top0, top1;
+  lin thresh;
+
+  /* Threshold distance is 2 * CONTEXT + 1 between two non-ignorable
+     changes, but only CONTEXT if one is ignorable.  Watch out for
+     integer overflow, though.  */
+  lin non_ignorable_threshold =
+    (LIN_MAX - 1) / 2 < context ? LIN_MAX : 2 * context + 1;
+  lin ignorable_threshold = context;
+
+  do
+    {
+      /* Compute number of first line in each file beyond this changed.  */
+      top0 = start->line0 + start->deleted;
+      top1 = start->line1 + start->inserted;
+      prev = start;
+      start = start->link;
+      thresh = (prev->ignore || (start && start->ignore)
+		? ignorable_threshold
+		: non_ignorable_threshold);
+      /* It is not supposed to matter which file we check in the end-test.
+	 If it would matter, crash.  */
+      if (start && start->line0 - top0 != start->line1 - top1)
+	abort ();
+    } while (start
+	     /* Keep going if less than THRESH lines
+		elapse before the affected line.  */
+	     && start->line0 - top0 < thresh);
+
+  return prev;
+}
+
+/* Set the `ignore' flag properly in each change in SCRIPT.
+   It should be 1 if all the lines inserted or deleted in that change
+   are ignorable lines.  */
+
+static void
+mark_ignorable (struct change *script)
+{
+  while (script)
+    {
+      struct change *next = script->link;
+      lin first0, last0, first1, last1;
+
+      /* Turn this change into a hunk: detach it from the others.  */
+      script->link = NULL;
+
+      /* Determine whether this change is ignorable.  */
+      script->ignore = ! analyze_hunk (script,
+				       &first0, &last0, &first1, &last1);
+
+      /* Reconnect the chain as before.  */
+      script->link = next;
+
+      /* Advance to the following change.  */
+      script = next;
+    }
+}
+
+/* Find the last function-header line in LINBUF prior to line number LINENUM.
+   This is a line containing a match for the regexp in `function_regexp'.
+   Return the address of the text, or NULL if no function-header is found.  */
+
+static char const *
+find_function (char const * const *linbuf, lin linenum)
+{
+  lin i = linenum;
+  lin last = find_function_last_search;
+  find_function_last_search = i;
+
+  while (last <= --i)
+    {
+      /* See if this line is what we want.  */
+      char const *line = linbuf[i];
+      size_t linelen = linbuf[i + 1] - line - 1;
+
+      /* FIXME: re_search's size args should be size_t, not int.  */
+      int len = MIN (linelen, INT_MAX);
+
+      if (0 <= re_search (&function_regexp, line, len, 0, len, NULL))
+	{
+	  find_function_last_match = i;
+	  return line;
+	}
+    }
+  /* If we search back to where we started searching the previous time,
+     find the line we found last time.  */
+  if (find_function_last_match != LIN_MAX)
+    return linbuf[find_function_last_match];
+
+  return NULL;
+}
diff --git a/src/diff.c b/src/diff.c
new file mode 100644
index 0000000..c096406
--- /dev/null
+++ b/src/diff.c
@@ -0,0 +1,1351 @@
+/* diff - compare files line by line
+
+   Copyright (C) 1988-1989, 1992-1994, 1996, 1998, 2001-2002, 2004, 2006-2007,
+   2009-2011 Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#define GDIFF_MAIN
+#include "diff.h"
+#include <assert.h>
+#include "paths.h"
+#include <c-stack.h>
+#include <dirname.h>
+#include <error.h>
+#include <exclude.h>
+#include <exitfail.h>
+#include <filenamecat.h>
+#include <file-type.h>
+#include <fnmatch.h>
+#include <getopt.h>
+#include <hard-locale.h>
+#include <prepargs.h>
+#include <progname.h>
+#include <sh-quote.h>
+#include <stat-time.h>
+#include <timespec.h>
+#include <version-etc.h>
+#include <xalloc.h>
+#include <xfreopen.h>
+
+/* The official name of this program (e.g., no `g' prefix).  */
+#define PROGRAM_NAME "diff"
+
+#define AUTHORS \
+  proper_name ("Paul Eggert"), \
+  proper_name ("Mike Haertel"), \
+  proper_name ("David Hayes"), \
+  proper_name ("Richard Stallman"), \
+  proper_name ("Len Tower")
+
+#ifndef GUTTER_WIDTH_MINIMUM
+# define GUTTER_WIDTH_MINIMUM 3
+#endif
+
+struct regexp_list
+{
+  char *regexps;	/* chars representing disjunction of the regexps */
+  size_t len;		/* chars used in `regexps' */
+  size_t size;		/* size malloc'ed for `regexps'; 0 if not malloc'ed */
+  bool multiple_regexps;/* Does `regexps' represent a disjunction?  */
+  struct re_pattern_buffer *buf;
+};
+
+static int compare_files (struct comparison const *, char const *, char const *);
+static void add_regexp (struct regexp_list *, char const *);
+static void summarize_regexp_list (struct regexp_list *);
+static void specify_style (enum output_style);
+static void specify_value (char const **, char const *, char const *);
+static void try_help (char const *, char const *) __attribute__((noreturn));
+static void check_stdout (void);
+static void usage (void);
+
+/* If comparing directories, compare their common subdirectories
+   recursively.  */
+static bool recursive;
+
+/* In context diffs, show previous lines that match these regexps.  */
+static struct regexp_list function_regexp_list;
+
+/* Ignore changes affecting only lines that match these regexps.  */
+static struct regexp_list ignore_regexp_list;
+
+#if O_BINARY
+/* Use binary I/O when reading and writing data (--binary).
+   On POSIX hosts, this has no effect.  */
+static bool binary;
+#else
+enum { binary = true };
+#endif
+
+/* When comparing directories, if a file appears only in one
+   directory, treat it as present but empty in the other (-N).
+   Then `patch' would create the file with appropriate contents.  */
+static bool new_file;
+
+/* When comparing directories, if a file appears only in the second
+   directory of the two, treat it as present but empty in the other
+   (--unidirectional-new-file).
+   Then `patch' would create the file with appropriate contents.  */
+static bool unidirectional_new_file;
+
+/* Report files compared that are the same (-s).
+   Normally nothing is output when that happens.  */
+static bool report_identical_files;
+
+static char const shortopts[] =
+"0123456789abBcC:dD:eEfF:hHiI:lL:nNpPqrsS:tTuU:vwW:x:X:yZ";
+
+/* Values for long options that do not have single-letter equivalents.  */
+enum
+{
+  BINARY_OPTION = CHAR_MAX + 1,
+  FROM_FILE_OPTION,
+  HELP_OPTION,
+  HORIZON_LINES_OPTION,
+  IGNORE_FILE_NAME_CASE_OPTION,
+  INHIBIT_HUNK_MERGE_OPTION,
+  LEFT_COLUMN_OPTION,
+  LINE_FORMAT_OPTION,
+  NO_IGNORE_FILE_NAME_CASE_OPTION,
+  NORMAL_OPTION,
+  SDIFF_MERGE_ASSIST_OPTION,
+  STRIP_TRAILING_CR_OPTION,
+  SUPPRESS_BLANK_EMPTY_OPTION,
+  SUPPRESS_COMMON_LINES_OPTION,
+  TABSIZE_OPTION,
+  TO_FILE_OPTION,
+
+  /* These options must be in sequence.  */
+  UNCHANGED_LINE_FORMAT_OPTION,
+  OLD_LINE_FORMAT_OPTION,
+  NEW_LINE_FORMAT_OPTION,
+
+  /* These options must be in sequence.  */
+  UNCHANGED_GROUP_FORMAT_OPTION,
+  OLD_GROUP_FORMAT_OPTION,
+  NEW_GROUP_FORMAT_OPTION,
+  CHANGED_GROUP_FORMAT_OPTION
+};
+
+static char const group_format_option[][sizeof "--unchanged-group-format"] =
+  {
+    "--unchanged-group-format",
+    "--old-group-format",
+    "--new-group-format",
+    "--changed-group-format"
+  };
+
+static char const line_format_option[][sizeof "--unchanged-line-format"] =
+  {
+    "--unchanged-line-format",
+    "--old-line-format",
+    "--new-line-format"
+  };
+
+static struct option const longopts[] =
+{
+  {"binary", 0, 0, BINARY_OPTION},
+  {"brief", 0, 0, 'q'},
+  {"changed-group-format", 1, 0, CHANGED_GROUP_FORMAT_OPTION},
+  {"context", 2, 0, 'C'},
+  {"ed", 0, 0, 'e'},
+  {"exclude", 1, 0, 'x'},
+  {"exclude-from", 1, 0, 'X'},
+  {"expand-tabs", 0, 0, 't'},
+  {"forward-ed", 0, 0, 'f'},
+  {"from-file", 1, 0, FROM_FILE_OPTION},
+  {"help", 0, 0, HELP_OPTION},
+  {"horizon-lines", 1, 0, HORIZON_LINES_OPTION},
+  {"ifdef", 1, 0, 'D'},
+  {"ignore-all-space", 0, 0, 'w'},
+  {"ignore-blank-lines", 0, 0, 'B'},
+  {"ignore-case", 0, 0, 'i'},
+  {"ignore-file-name-case", 0, 0, IGNORE_FILE_NAME_CASE_OPTION},
+  {"ignore-matching-lines", 1, 0, 'I'},
+  {"ignore-space-change", 0, 0, 'b'},
+  {"ignore-tab-expansion", 0, 0, 'E'},
+  {"ignore-trailing-space", 0, 0, 'Z'},
+  {"inhibit-hunk-merge", 0, 0, INHIBIT_HUNK_MERGE_OPTION},
+  {"initial-tab", 0, 0, 'T'},
+  {"label", 1, 0, 'L'},
+  {"left-column", 0, 0, LEFT_COLUMN_OPTION},
+  {"line-format", 1, 0, LINE_FORMAT_OPTION},
+  {"minimal", 0, 0, 'd'},
+  {"new-file", 0, 0, 'N'},
+  {"new-group-format", 1, 0, NEW_GROUP_FORMAT_OPTION},
+  {"new-line-format", 1, 0, NEW_LINE_FORMAT_OPTION},
+  {"no-ignore-file-name-case", 0, 0, NO_IGNORE_FILE_NAME_CASE_OPTION},
+  {"normal", 0, 0, NORMAL_OPTION},
+  {"old-group-format", 1, 0, OLD_GROUP_FORMAT_OPTION},
+  {"old-line-format", 1, 0, OLD_LINE_FORMAT_OPTION},
+  {"paginate", 0, 0, 'l'},
+  {"rcs", 0, 0, 'n'},
+  {"recursive", 0, 0, 'r'},
+  {"report-identical-files", 0, 0, 's'},
+  {"sdiff-merge-assist", 0, 0, SDIFF_MERGE_ASSIST_OPTION},
+  {"show-c-function", 0, 0, 'p'},
+  {"show-function-line", 1, 0, 'F'},
+  {"side-by-side", 0, 0, 'y'},
+  {"speed-large-files", 0, 0, 'H'},
+  {"starting-file", 1, 0, 'S'},
+  {"strip-trailing-cr", 0, 0, STRIP_TRAILING_CR_OPTION},
+  {"suppress-blank-empty", 0, 0, SUPPRESS_BLANK_EMPTY_OPTION},
+  {"suppress-common-lines", 0, 0, SUPPRESS_COMMON_LINES_OPTION},
+  {"tabsize", 1, 0, TABSIZE_OPTION},
+  {"text", 0, 0, 'a'},
+  {"to-file", 1, 0, TO_FILE_OPTION},
+  {"unchanged-group-format", 1, 0, UNCHANGED_GROUP_FORMAT_OPTION},
+  {"unchanged-line-format", 1, 0, UNCHANGED_LINE_FORMAT_OPTION},
+  {"unidirectional-new-file", 0, 0, 'P'},
+  {"unified", 2, 0, 'U'},
+  {"version", 0, 0, 'v'},
+  {"width", 1, 0, 'W'},
+  {0, 0, 0, 0}
+};
+
+/* Return a string containing the command options with which diff was invoked.
+   Spaces appear between what were separate ARGV-elements.
+   There is a space at the beginning but none at the end.
+   If there were no options, the result is an empty string.
+
+   Arguments: OPTIONVEC, a vector containing separate ARGV-elements, and COUNT,
+   the length of that vector.  */
+
+static char *
+option_list (char **optionvec, int count)
+{
+  int i;
+  size_t size = 1;
+  char *result;
+  char *p;
+
+  for (i = 0; i < count; i++)
+    size += 1 + shell_quote_length (optionvec[i]);
+
+  p = result = xmalloc (size);
+
+  for (i = 0; i < count; i++)
+    {
+      *p++ = ' ';
+      p = shell_quote_copy (p, optionvec[i]);
+    }
+
+  *p = '\0';
+  return result;
+}
+
+
+/* Return an option value suitable for add_exclude.  */
+
+static int
+exclude_options (void)
+{
+  return EXCLUDE_WILDCARDS | (ignore_file_name_case ? FNM_CASEFOLD : 0);
+}
+
+int
+main (int argc, char **argv)
+{
+  int exit_status = EXIT_SUCCESS;
+  int c;
+  int i;
+  int prev = -1;
+  lin ocontext = -1;
+  bool explicit_context = false;
+  size_t width = 0;
+  bool show_c_function = false;
+  char const *from_file = NULL;
+  char const *to_file = NULL;
+  uintmax_t numval;
+  char *numend;
+
+  /* Do our initializations.  */
+  exit_failure = EXIT_TROUBLE;
+  initialize_main (&argc, &argv);
+  set_program_name (argv[0]);
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+  c_stack_action (0);
+  function_regexp_list.buf = &function_regexp;
+  ignore_regexp_list.buf = &ignore_regexp;
+  re_set_syntax (RE_SYNTAX_GREP | RE_NO_POSIX_BACKTRACKING);
+  excluded = new_exclude ();
+
+  /* Decode the options.  */
+
+  while ((c = getopt_long (argc, argv, shortopts, longopts, NULL)) != -1)
+    {
+      switch (c)
+	{
+	case 0:
+	  break;
+
+	case '0':
+	case '1':
+	case '2':
+	case '3':
+	case '4':
+	case '5':
+	case '6':
+	case '7':
+	case '8':
+	case '9':
+	  if (! ISDIGIT (prev))
+	    ocontext = c - '0';
+	  else if (LIN_MAX / 10 < ocontext
+		   || ((ocontext = 10 * ocontext + c - '0') < 0))
+	    ocontext = LIN_MAX;
+	  break;
+
+	case 'a':
+	  text = true;
+	  break;
+
+	case 'b':
+	  if (ignore_white_space < IGNORE_SPACE_CHANGE)
+	    ignore_white_space = IGNORE_SPACE_CHANGE;
+	  break;
+
+	case 'Z':
+	  if (ignore_white_space < IGNORE_SPACE_CHANGE)
+	    ignore_white_space |= IGNORE_TRAILING_SPACE;
+	  break;
+
+	case 'B':
+	  ignore_blank_lines = true;
+	  break;
+
+	case 'C':
+	case 'U':
+	  {
+	    if (optarg)
+	      {
+		numval = strtoumax (optarg, &numend, 10);
+		if (*numend)
+		  try_help ("invalid context length `%s'", optarg);
+		if (LIN_MAX < numval)
+		  numval = LIN_MAX;
+	      }
+	    else
+	      numval = 3;
+
+	    specify_style (c == 'U' ? OUTPUT_UNIFIED : OUTPUT_CONTEXT);
+	    if (context < numval)
+	      context = numval;
+	    explicit_context = true;
+	  }
+	  break;
+
+	case 'c':
+	  specify_style (OUTPUT_CONTEXT);
+	  if (context < 3)
+	    context = 3;
+	  break;
+
+	case 'd':
+	  minimal = true;
+	  break;
+
+	case 'D':
+	  specify_style (OUTPUT_IFDEF);
+	  {
+	    static char const C_ifdef_group_formats[] =
+	      "%%=%c#ifndef %s\n%%<#endif /* ! %s */\n%c#ifdef %s\n%%>#endif /* %s */\n%c#ifndef %s\n%%<#else /* %s */\n%%>#endif /* %s */\n";
+	    char *b = xmalloc (sizeof C_ifdef_group_formats
+			       + 7 * strlen (optarg) - 14 /* 7*"%s" */
+			       - 8 /* 5*"%%" + 3*"%c" */);
+	    sprintf (b, C_ifdef_group_formats,
+		     0,
+		     optarg, optarg, 0,
+		     optarg, optarg, 0,
+		     optarg, optarg, optarg);
+	    for (i = 0; i < sizeof group_format / sizeof group_format[0]; i++)
+	      {
+		specify_value (&group_format[i], b, "-D");
+		b += strlen (b) + 1;
+	      }
+	  }
+	  break;
+
+	case 'e':
+	  specify_style (OUTPUT_ED);
+	  break;
+
+	case 'E':
+	  if (ignore_white_space < IGNORE_SPACE_CHANGE)
+	    ignore_white_space |= IGNORE_TAB_EXPANSION;
+	  break;
+
+	case 'f':
+	  specify_style (OUTPUT_FORWARD_ED);
+	  break;
+
+	case 'F':
+	  add_regexp (&function_regexp_list, optarg);
+	  break;
+
+	case 'h':
+	  /* Split the files into chunks for faster processing.
+	     Usually does not change the result.
+
+	     This currently has no effect.  */
+	  break;
+
+	case 'H':
+	  speed_large_files = true;
+	  break;
+
+	case 'i':
+	  ignore_case = true;
+	  break;
+
+	case 'I':
+	  add_regexp (&ignore_regexp_list, optarg);
+	  break;
+
+	case 'l':
+	  if (!pr_program[0])
+	    try_help ("pagination not supported on this host", NULL);
+	  paginate = true;
+#ifdef SIGCHLD
+	  /* Pagination requires forking and waiting, and
+	     System V fork+wait does not work if SIGCHLD is ignored.  */
+	  signal (SIGCHLD, SIG_DFL);
+#endif
+	  break;
+
+	case 'L':
+	  if (!file_label[0])
+	    file_label[0] = optarg;
+	  else if (!file_label[1])
+	    file_label[1] = optarg;
+	  else
+	    fatal ("too many file label options");
+	  break;
+
+	case 'n':
+	  specify_style (OUTPUT_RCS);
+	  break;
+
+	case 'N':
+	  new_file = true;
+	  break;
+
+	case 'p':
+	  show_c_function = true;
+	  add_regexp (&function_regexp_list, "^[[:alpha:]$_]");
+	  break;
+
+	case 'P':
+	  unidirectional_new_file = true;
+	  break;
+
+	case 'q':
+	  brief = true;
+	  break;
+
+	case 'r':
+	  recursive = true;
+	  break;
+
+	case 's':
+	  report_identical_files = true;
+	  break;
+
+	case 'S':
+	  specify_value (&starting_file, optarg, "-S");
+	  break;
+
+	case 't':
+	  expand_tabs = true;
+	  break;
+
+	case 'T':
+	  initial_tab = true;
+	  break;
+
+	case 'u':
+	  specify_style (OUTPUT_UNIFIED);
+	  if (context < 3)
+	    context = 3;
+	  break;
+
+	case 'v':
+	  version_etc (stdout, PROGRAM_NAME, PACKAGE_NAME, Version,
+		       AUTHORS, (char *) NULL);
+	  check_stdout ();
+	  return EXIT_SUCCESS;
+
+	case 'w':
+	  ignore_white_space = IGNORE_ALL_SPACE;
+	  break;
+
+	case 'x':
+	  add_exclude (excluded, optarg, exclude_options ());
+	  break;
+
+	case 'X':
+	  if (add_exclude_file (add_exclude, excluded, optarg,
+				exclude_options (), '\n'))
+	    pfatal_with_name (optarg);
+	  break;
+
+	case 'y':
+	  specify_style (OUTPUT_SDIFF);
+	  break;
+
+	case 'W':
+	  numval = strtoumax (optarg, &numend, 10);
+	  if (! (0 < numval && numval <= SIZE_MAX) || *numend)
+	    try_help ("invalid width `%s'", optarg);
+	  if (width != numval)
+	    {
+	      if (width)
+		fatal ("conflicting width options");
+	      width = numval;
+	    }
+	  break;
+
+	case BINARY_OPTION:
+#if O_BINARY
+	  binary = true;
+	  if (! isatty (STDOUT_FILENO))
+	    xfreopen (NULL, "wb", stdout);
+#endif
+	  break;
+
+	case FROM_FILE_OPTION:
+	  specify_value (&from_file, optarg, "--from-file");
+	  break;
+
+	case HELP_OPTION:
+	  usage ();
+	  check_stdout ();
+	  return EXIT_SUCCESS;
+
+	case HORIZON_LINES_OPTION:
+	  numval = strtoumax (optarg, &numend, 10);
+	  if (*numend)
+	    try_help ("invalid horizon length `%s'", optarg);
+	  horizon_lines = MAX (horizon_lines, MIN (numval, LIN_MAX));
+	  break;
+
+	case IGNORE_FILE_NAME_CASE_OPTION:
+	  ignore_file_name_case = true;
+	  break;
+
+	case INHIBIT_HUNK_MERGE_OPTION:
+	  /* This option is obsolete, but accept it for backward
+             compatibility.  */
+	  break;
+
+	case LEFT_COLUMN_OPTION:
+	  left_column = true;
+	  break;
+
+	case LINE_FORMAT_OPTION:
+	  specify_style (OUTPUT_IFDEF);
+	  for (i = 0; i < sizeof line_format / sizeof line_format[0]; i++)
+	    specify_value (&line_format[i], optarg, "--line-format");
+	  break;
+
+	case NO_IGNORE_FILE_NAME_CASE_OPTION:
+	  ignore_file_name_case = false;
+	  break;
+
+	case NORMAL_OPTION:
+	  specify_style (OUTPUT_NORMAL);
+	  break;
+
+	case SDIFF_MERGE_ASSIST_OPTION:
+	  specify_style (OUTPUT_SDIFF);
+	  sdiff_merge_assist = true;
+	  break;
+
+	case STRIP_TRAILING_CR_OPTION:
+	  strip_trailing_cr = true;
+	  break;
+
+	case SUPPRESS_BLANK_EMPTY_OPTION:
+	  suppress_blank_empty = true;
+	  break;
+
+	case SUPPRESS_COMMON_LINES_OPTION:
+	  suppress_common_lines = true;
+	  break;
+
+	case TABSIZE_OPTION:
+	  numval = strtoumax (optarg, &numend, 10);
+	  if (! (0 < numval && numval <= SIZE_MAX) || *numend)
+	    try_help ("invalid tabsize `%s'", optarg);
+	  if (tabsize != numval)
+	    {
+	      if (tabsize)
+		fatal ("conflicting tabsize options");
+	      tabsize = numval;
+	    }
+	  break;
+
+	case TO_FILE_OPTION:
+	  specify_value (&to_file, optarg, "--to-file");
+	  break;
+
+	case UNCHANGED_LINE_FORMAT_OPTION:
+	case OLD_LINE_FORMAT_OPTION:
+	case NEW_LINE_FORMAT_OPTION:
+	  specify_style (OUTPUT_IFDEF);
+	  c -= UNCHANGED_LINE_FORMAT_OPTION;
+	  specify_value (&line_format[c], optarg, line_format_option[c]);
+	  break;
+
+	case UNCHANGED_GROUP_FORMAT_OPTION:
+	case OLD_GROUP_FORMAT_OPTION:
+	case NEW_GROUP_FORMAT_OPTION:
+	case CHANGED_GROUP_FORMAT_OPTION:
+	  specify_style (OUTPUT_IFDEF);
+	  c -= UNCHANGED_GROUP_FORMAT_OPTION;
+	  specify_value (&group_format[c], optarg, group_format_option[c]);
+	  break;
+
+	default:
+	  try_help (NULL, NULL);
+	}
+      prev = c;
+    }
+
+  if (output_style == OUTPUT_UNSPECIFIED)
+    {
+      if (show_c_function)
+	{
+	  specify_style (OUTPUT_CONTEXT);
+	  if (ocontext < 0)
+	    context = 3;
+	}
+      else
+	specify_style (OUTPUT_NORMAL);
+    }
+
+  if (output_style != OUTPUT_CONTEXT || hard_locale (LC_TIME))
+    {
+#if (defined STAT_TIMESPEC || defined STAT_TIMESPEC_NS \
+     || defined HAVE_STRUCT_STAT_ST_SPARE1)
+      time_format = "%Y-%m-%d %H:%M:%S.%N %z";
+#else
+      time_format = "%Y-%m-%d %H:%M:%S %z";
+#endif
+    }
+  else
+    {
+      /* See POSIX 1003.1-2001 for this format.  */
+      time_format = "%a %b %e %T %Y";
+    }
+
+  if (0 <= ocontext
+      && (output_style == OUTPUT_CONTEXT
+	  || output_style == OUTPUT_UNIFIED)
+      && (context < ocontext
+	  || (ocontext < context && ! explicit_context)))
+    context = ocontext;
+
+  if (! tabsize)
+    tabsize = 8;
+  if (! width)
+    width = 130;
+
+  {
+    /* Maximize first the half line width, and then the gutter width,
+       according to the following constraints:
+
+	1.  Two half lines plus a gutter must fit in a line.
+	2.  If the half line width is nonzero:
+	    a.  The gutter width is at least GUTTER_WIDTH_MINIMUM.
+	    b.  If tabs are not expanded to spaces,
+		a half line plus a gutter is an integral number of tabs,
+		so that tabs in the right column line up.  */
+
+    intmax_t t = expand_tabs ? 1 : tabsize;
+    intmax_t w = width;
+    intmax_t off = (w + t + GUTTER_WIDTH_MINIMUM) / (2 * t)  *  t;
+    sdiff_half_width = MAX (0, MIN (off - GUTTER_WIDTH_MINIMUM, w - off)),
+    sdiff_column2_offset = sdiff_half_width ? off : w;
+  }
+
+  /* Make the horizon at least as large as the context, so that
+     shift_boundaries has more freedom to shift the first and last hunks.  */
+  if (horizon_lines < context)
+    horizon_lines = context;
+
+  summarize_regexp_list (&function_regexp_list);
+  summarize_regexp_list (&ignore_regexp_list);
+
+  if (output_style == OUTPUT_IFDEF)
+    {
+      for (i = 0; i < sizeof line_format / sizeof line_format[0]; i++)
+	if (!line_format[i])
+	  line_format[i] = "%l\n";
+      if (!group_format[OLD])
+	group_format[OLD]
+	  = group_format[CHANGED] ? group_format[CHANGED] : "%<";
+      if (!group_format[NEW])
+	group_format[NEW]
+	  = group_format[CHANGED] ? group_format[CHANGED] : "%>";
+      if (!group_format[UNCHANGED])
+	group_format[UNCHANGED] = "%=";
+      if (!group_format[CHANGED])
+	group_format[CHANGED] = concat (group_format[OLD],
+					group_format[NEW], "");
+    }
+
+  no_diff_means_no_output =
+    (output_style == OUTPUT_IFDEF ?
+      (!*group_format[UNCHANGED]
+       || (STREQ (group_format[UNCHANGED], "%=")
+	   && !*line_format[UNCHANGED]))
+     : (output_style != OUTPUT_SDIFF) | suppress_common_lines);
+
+  files_can_be_treated_as_binary =
+    (brief & binary
+     & ~ (ignore_blank_lines | ignore_case | strip_trailing_cr
+	  | (ignore_regexp_list.regexps || ignore_white_space)));
+
+  switch_string = option_list (argv + 1, optind - 1);
+
+  if (from_file)
+    {
+      if (to_file)
+	fatal ("--from-file and --to-file both specified");
+      else
+	for (; optind < argc; optind++)
+	  {
+	    int status = compare_files (NULL, from_file, argv[optind]);
+	    if (exit_status < status)
+	      exit_status = status;
+	  }
+    }
+  else
+    {
+      if (to_file)
+	for (; optind < argc; optind++)
+	  {
+	    int status = compare_files (NULL, argv[optind], to_file);
+	    if (exit_status < status)
+	      exit_status = status;
+	  }
+      else
+	{
+	  if (argc - optind != 2)
+	    {
+	      if (argc - optind < 2)
+		try_help ("missing operand after `%s'", argv[argc - 1]);
+	      else
+		try_help ("extra operand `%s'", argv[optind + 2]);
+	    }
+
+	  exit_status = compare_files (NULL, argv[optind], argv[optind + 1]);
+	}
+    }
+
+  /* Print any messages that were saved up for last.  */
+  print_message_queue ();
+
+  check_stdout ();
+  exit (exit_status);
+  return exit_status;
+}
+
+/* Append to REGLIST the regexp PATTERN.  */
+
+static void
+add_regexp (struct regexp_list *reglist, char const *pattern)
+{
+  size_t patlen = strlen (pattern);
+  char const *m = re_compile_pattern (pattern, patlen, reglist->buf);
+
+  if (m != 0)
+    error (0, 0, "%s: %s", pattern, m);
+  else
+    {
+      char *regexps = reglist->regexps;
+      size_t len = reglist->len;
+      bool multiple_regexps = reglist->multiple_regexps = regexps != 0;
+      size_t newlen = reglist->len = len + 2 * multiple_regexps + patlen;
+      size_t size = reglist->size;
+
+      if (size <= newlen)
+	{
+	  if (!size)
+	    size = 1;
+
+	  do size *= 2;
+	  while (size <= newlen);
+
+	  reglist->size = size;
+	  reglist->regexps = regexps = xrealloc (regexps, size);
+	}
+      if (multiple_regexps)
+	{
+	  regexps[len++] = '\\';
+	  regexps[len++] = '|';
+	}
+      memcpy (regexps + len, pattern, patlen + 1);
+    }
+}
+
+/* Ensure that REGLIST represents the disjunction of its regexps.
+   This is done here, rather than earlier, to avoid O(N^2) behavior.  */
+
+static void
+summarize_regexp_list (struct regexp_list *reglist)
+{
+  if (reglist->regexps)
+    {
+      /* At least one regexp was specified.  Allocate a fastmap for it.  */
+      reglist->buf->fastmap = xmalloc (1 << CHAR_BIT);
+      if (reglist->multiple_regexps)
+	{
+	  /* Compile the disjunction of the regexps.
+	     (If just one regexp was specified, it is already compiled.)  */
+	  char const *m = re_compile_pattern (reglist->regexps, reglist->len,
+					      reglist->buf);
+	  if (m)
+	    error (EXIT_TROUBLE, 0, "%s: %s", reglist->regexps, m);
+	}
+    }
+}
+
+static void
+try_help (char const *reason_msgid, char const *operand)
+{
+  if (reason_msgid)
+    error (0, 0, _(reason_msgid), operand);
+  error (EXIT_TROUBLE, 0, _("Try `%s --help' for more information."),
+	 program_name);
+  abort ();
+}
+
+static void
+check_stdout (void)
+{
+  if (ferror (stdout))
+    fatal ("write failed");
+  else if (fclose (stdout) != 0)
+    pfatal_with_name (_("standard output"));
+}
+
+static char const * const option_help_msgid[] = {
+  N_("    --normal                  output a normal diff (the default)"),
+  N_("-q, --brief                   report only when files differ"),
+  N_("-s, --report-identical-files  report when two files are the same"),
+  N_("-c, -C NUM, --context[=NUM]   output NUM (default 3) lines of copied context"),
+  N_("-u, -U NUM, --unified[=NUM]   output NUM (default 3) lines of unified context"),
+  N_("-e, --ed                      output an ed script"),
+  N_("-n, --rcs                     output an RCS format diff"),
+  N_("-y, --side-by-side            output in two columns"),
+  N_("-W, --width=NUM               output at most NUM (default 130) print columns"),
+  N_("    --left-column             output only the left column of common lines"),
+  N_("    --suppress-common-lines   do not output common lines"),
+  "",
+  N_("-p, --show-c-function         show which C function each change is in"),
+  N_("-F, --show-function-line=RE   show the most recent line matching RE"),
+  N_("    --label LABEL             use LABEL instead of file name\n"
+     "                                (can be repeated)"),
+  "",
+  N_("-t, --expand-tabs             expand tabs to spaces in output"),
+  N_("-T, --initial-tab             make tabs line up by prepending a tab"),
+  N_("    --tabsize=NUM             tab stops every NUM (default 8) print columns"),
+  N_("    --suppress-blank-empty    suppress space or tab before empty output lines"),
+  N_("-l, --paginate                pass output through `pr' to paginate it"),
+  "",
+  N_("-r, --recursive                 recursively compare any subdirectories found"),
+  N_("-N, --new-file                  treat absent files as empty"),
+  N_("    --unidirectional-new-file   treat absent first files as empty"),
+  N_("    --ignore-file-name-case     ignore case when comparing file names"),
+  N_("    --no-ignore-file-name-case  consider case when comparing file names"),
+  N_("-x, --exclude=PAT               exclude files that match PAT"),
+  N_("-X, --exclude-from=FILE         exclude files that match any pattern in FILE"),
+  N_("-S, --starting-file=FILE        start with FILE when comparing directories"),
+  N_("    --from-file=FILE1           compare FILE1 to all operands;\n"
+     "                                  FILE1 can be a directory"),
+  N_("    --to-file=FILE2             compare all operands to FILE2;\n"
+     "                                  FILE2 can be a directory"),
+  "",
+  N_("-i, --ignore-case               ignore case differences in file contents"),
+  N_("-E, --ignore-tab-expansion      ignore changes due to tab expansion"),
+  N_("-Z, --ignore-trailing-space     ignore white space at line end"),
+  N_("-b, --ignore-space-change       ignore changes in the amount of white space"),
+  N_("-w, --ignore-all-space          ignore all white space"),
+  N_("-B, --ignore-blank-lines        ignore changes whose lines are all blank"),
+  N_("-I, --ignore-matching-lines=RE  ignore changes whose lines all match RE"),
+  "",
+  N_("-a, --text                      treat all files as text"),
+  N_("    --strip-trailing-cr         strip trailing carriage return on input"),
+#if O_BINARY
+  N_("    --binary                    read and write data in binary mode"),
+#endif
+  "",
+  N_("-D, --ifdef=NAME                output merged file with `#ifdef NAME' diffs"),
+  N_("    --GTYPE-group-format=GFMT   format GTYPE input groups with GFMT"),
+  N_("    --line-format=LFMT          format all input lines with LFMT"),
+  N_("    --LTYPE-line-format=LFMT    format LTYPE input lines with LFMT"),
+  N_("  These format options provide fine-grained control over the output\n"
+     "    of diff, generalizing -D/--ifdef."),
+  N_("  LTYPE is `old', `new', or `unchanged'.  GTYPE is LTYPE or `changed'."),
+  N_("  GFMT (only) may contain:\n\
+    %<  lines from FILE1\n\
+    %>  lines from FILE2\n\
+    %=  lines common to FILE1 and FILE2\n\
+    %[-][WIDTH][.[PREC]]{doxX}LETTER  printf-style spec for LETTER\n\
+      LETTERs are as follows for new group, lower case for old group:\n\
+        F  first line number\n\
+        L  last line number\n\
+        N  number of lines = L-F+1\n\
+        E  F-1\n\
+        M  L+1\n\
+    %(A=B?T:E)  if A equals B then T else E"),
+  N_("  LFMT (only) may contain:\n\
+    %L  contents of line\n\
+    %l  contents of line, excluding any trailing newline\n\
+    %[-][WIDTH][.[PREC]]{doxX}n  printf-style spec for input line number"),
+  N_("  Both GFMT and LFMT may contain:\n\
+    %%  %\n\
+    %c'C'  the single character C\n\
+    %c'\\OOO'  the character with octal code OOO\n\
+    C    the character C (other characters represent themselves)"),
+  "",
+  N_("-d, --minimal            try hard to find a smaller set of changes"),
+  N_("    --horizon-lines=NUM  keep NUM lines of the common prefix and suffix"),
+  N_("    --speed-large-files  assume large files and many scattered small changes"),
+  "",
+  N_("    --help               display this help and exit"),
+  N_("-v, --version            output version information and exit"),
+  "",
+  N_("FILES are `FILE1 FILE2' or `DIR1 DIR2' or `DIR FILE...' or `FILE... DIR'."),
+  N_("If --from-file or --to-file is given, there are no restrictions on FILE(s)."),
+  N_("If a FILE is `-', read standard input."),
+  N_("Exit status is 0 if inputs are the same, 1 if different, 2 if trouble."),
+  0
+};
+
+static void
+usage (void)
+{
+  char const * const *p;
+
+  printf (_("Usage: %s [OPTION]... FILES\n"), program_name);
+  printf ("%s\n\n", _("Compare FILES line by line."));
+
+  fputs (_("\
+Mandatory arguments to long options are mandatory for short options too.\n\
+"), stdout);
+
+  for (p = option_help_msgid;  *p;  p++)
+    {
+      if (!**p)
+	putchar ('\n');
+      else
+	{
+	  char const *msg = _(*p);
+	  char const *nl;
+	  while ((nl = strchr (msg, '\n')))
+	    {
+	      int msglen = nl + 1 - msg;
+	      printf ("  %.*s", msglen, msg);
+	      msg = nl + 1;
+	    }
+
+	  printf ("  %s\n" + 2 * (*msg != ' ' && *msg != '-'), msg);
+	}
+    }
+  emit_bug_reporting_address ();
+}
+
+/* Set VAR to VALUE, reporting an OPTION error if this is a
+   conflict.  */
+static void
+specify_value (char const **var, char const *value, char const *option)
+{
+  if (*var && ! STREQ (*var, value))
+    {
+      error (0, 0, _("conflicting %s option value `%s'"), option, value);
+      try_help (NULL, NULL);
+    }
+  *var = value;
+}
+
+/* Set the output style to STYLE, diagnosing conflicts.  */
+static void
+specify_style (enum output_style style)
+{
+  if (output_style != style)
+    {
+      if (output_style != OUTPUT_UNSPECIFIED)
+	try_help ("conflicting output style options", NULL);
+      output_style = style;
+    }
+}
+
+/* Set the last-modified time of *ST to be the current time.  */
+
+static void
+set_mtime_to_now (struct stat *st)
+{
+#ifdef STAT_TIMESPEC
+  gettime (&STAT_TIMESPEC (st, st_mtim));
+#else
+  struct timespec t;
+  gettime (&t);
+  st->st_mtime = t.tv_sec;
+# if defined STAT_TIMESPEC_NS
+  STAT_TIMESPEC_NS (st, st_mtim) = t.tv_nsec;
+# elif defined HAVE_STRUCT_STAT_ST_SPARE1
+  st->st_spare1 = t.tv_nsec / 1000;
+# endif
+#endif
+}
+
+/* Compare two files (or dirs) with parent comparison PARENT
+   and names NAME0 and NAME1.
+   (If PARENT is null, then the first name is just NAME0, etc.)
+   This is self-contained; it opens the files and closes them.
+
+   Value is EXIT_SUCCESS if files are the same, EXIT_FAILURE if
+   different, EXIT_TROUBLE if there is a problem opening them.  */
+
+static int
+compare_files (struct comparison const *parent,
+	       char const *name0,
+	       char const *name1)
+{
+  struct comparison cmp;
+#define DIR_P(f) (S_ISDIR (cmp.file[f].stat.st_mode) != 0)
+  register int f;
+  int status = EXIT_SUCCESS;
+  bool same_files;
+  char *free0;
+  char *free1;
+
+  /* If this is directory comparison, perhaps we have a file
+     that exists only in one of the directories.
+     If so, just print a message to that effect.  */
+
+  if (! ((name0 && name1)
+	 || (unidirectional_new_file && name1)
+	 || new_file))
+    {
+      char const *name = name0 ? name0 : name1;
+      char const *dir = parent->file[!name0].name;
+
+      /* See POSIX 1003.1-2001 for this format.  */
+      message ("Only in %s: %s\n", dir, name);
+
+      /* Return EXIT_FAILURE so that diff_dirs will return
+	 EXIT_FAILURE ("some files differ").  */
+      return EXIT_FAILURE;
+    }
+
+  memset (cmp.file, 0, sizeof cmp.file);
+  cmp.parent = parent;
+
+  /* cmp.file[f].desc markers */
+#define NONEXISTENT (-1) /* nonexistent file */
+#define UNOPENED (-2) /* unopened file (e.g. directory) */
+#define ERRNO_ENCODE(errno) (-3 - (errno)) /* encoded errno value */
+
+#define ERRNO_DECODE(desc) (-3 - (desc)) /* inverse of ERRNO_ENCODE */
+
+  cmp.file[0].desc = name0 ? UNOPENED : NONEXISTENT;
+  cmp.file[1].desc = name1 ? UNOPENED : NONEXISTENT;
+
+  /* Now record the full name of each file, including nonexistent ones.  */
+
+  if (!name0)
+    name0 = name1;
+  if (!name1)
+    name1 = name0;
+
+  if (!parent)
+    {
+      free0 = NULL;
+      free1 = NULL;
+      cmp.file[0].name = name0;
+      cmp.file[1].name = name1;
+    }
+  else
+    {
+      cmp.file[0].name = free0
+	= file_name_concat (parent->file[0].name, name0, NULL);
+      cmp.file[1].name = free1
+	= file_name_concat (parent->file[1].name, name1, NULL);
+    }
+
+  /* Stat the files.  */
+
+  for (f = 0; f < 2; f++)
+    {
+      if (cmp.file[f].desc != NONEXISTENT)
+	{
+	  if (f && file_name_cmp (cmp.file[f].name, cmp.file[0].name) == 0)
+	    {
+	      cmp.file[f].desc = cmp.file[0].desc;
+	      cmp.file[f].stat = cmp.file[0].stat;
+	    }
+	  else if (STREQ (cmp.file[f].name, "-"))
+	    {
+	      cmp.file[f].desc = STDIN_FILENO;
+	      if (O_BINARY && binary && ! isatty (STDIN_FILENO))
+		xfreopen (NULL, "rb", stdin);
+	      if (fstat (STDIN_FILENO, &cmp.file[f].stat) != 0)
+		cmp.file[f].desc = ERRNO_ENCODE (errno);
+	      else
+		{
+		  if (S_ISREG (cmp.file[f].stat.st_mode))
+		    {
+		      off_t pos = lseek (STDIN_FILENO, 0, SEEK_CUR);
+		      if (pos < 0)
+			cmp.file[f].desc = ERRNO_ENCODE (errno);
+		      else
+			cmp.file[f].stat.st_size =
+			  MAX (0, cmp.file[f].stat.st_size - pos);
+		    }
+
+		  /* POSIX 1003.1-2001 requires current time for
+		     stdin.  */
+		  set_mtime_to_now (&cmp.file[f].stat);
+		}
+	    }
+	  else if (stat (cmp.file[f].name, &cmp.file[f].stat) != 0)
+	    cmp.file[f].desc = ERRNO_ENCODE (errno);
+	}
+    }
+
+  /* Mark files as nonexistent as needed for -N and -P, if they are
+     inaccessible empty regular files (the kind of files that 'patch'
+     creates to indicate nonexistent backups), or if they are
+     top-level files that do not exist but their counterparts do
+     exist.  */
+  for (f = 0; f < 2; f++)
+    if ((new_file || (f == 0 && unidirectional_new_file))
+	&& (cmp.file[f].desc == UNOPENED
+	    ? (S_ISREG (cmp.file[f].stat.st_mode)
+	       && ! (cmp.file[f].stat.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO))
+	       && cmp.file[f].stat.st_size == 0)
+	    : (cmp.file[f].desc == ERRNO_ENCODE (ENOENT)
+	       && ! parent
+	       && cmp.file[1 - f].desc == UNOPENED)))
+      cmp.file[f].desc = NONEXISTENT;
+
+  for (f = 0; f < 2; f++)
+    if (cmp.file[f].desc == NONEXISTENT)
+      {
+	memset (&cmp.file[f].stat, 0, sizeof cmp.file[f].stat);
+	cmp.file[f].stat.st_mode = cmp.file[1 - f].stat.st_mode;
+      }
+
+  for (f = 0; f < 2; f++)
+    {
+      int e = ERRNO_DECODE (cmp.file[f].desc);
+      if (0 <= e)
+	{
+	  errno = e;
+	  perror_with_name (cmp.file[f].name);
+	  status = EXIT_TROUBLE;
+	}
+    }
+
+  if (status == EXIT_SUCCESS && ! parent && DIR_P (0) != DIR_P (1))
+    {
+      /* If one is a directory, and it was specified in the command line,
+	 use the file in that dir with the other file's basename.  */
+
+      int fnm_arg = DIR_P (0);
+      int dir_arg = 1 - fnm_arg;
+      char const *fnm = cmp.file[fnm_arg].name;
+      char const *dir = cmp.file[dir_arg].name;
+      char const *filename = cmp.file[dir_arg].name = free0
+	= find_dir_file_pathname (dir, last_component (fnm));
+
+      if (STREQ (fnm, "-"))
+	fatal ("cannot compare `-' to a directory");
+
+      if (stat (filename, &cmp.file[dir_arg].stat) != 0)
+	{
+	  perror_with_name (filename);
+	  status = EXIT_TROUBLE;
+	}
+    }
+
+  if (status != EXIT_SUCCESS)
+    {
+      /* One of the files should exist but does not.  */
+    }
+  else if (cmp.file[0].desc == NONEXISTENT
+	   && cmp.file[1].desc == NONEXISTENT)
+    {
+      /* Neither file "exists", so there's nothing to compare.  */
+    }
+  else if ((same_files
+	    = (cmp.file[0].desc != NONEXISTENT
+	       && cmp.file[1].desc != NONEXISTENT
+	       && 0 < same_file (&cmp.file[0].stat, &cmp.file[1].stat)
+	       && same_file_attributes (&cmp.file[0].stat,
+					&cmp.file[1].stat)))
+	   && no_diff_means_no_output)
+    {
+      /* The two named files are actually the same physical file.
+	 We know they are identical without actually reading them.  */
+    }
+  else if (DIR_P (0) & DIR_P (1))
+    {
+      if (output_style == OUTPUT_IFDEF)
+	fatal ("-D option not supported with directories");
+
+      /* If both are directories, compare the files in them.  */
+
+      if (parent && !recursive)
+	{
+	  /* But don't compare dir contents one level down
+	     unless -r was specified.
+	     See POSIX 1003.1-2001 for this format.  */
+	  message ("Common subdirectories: %s and %s\n",
+		   cmp.file[0].name, cmp.file[1].name);
+	}
+      else
+	status = diff_dirs (&cmp, compare_files);
+    }
+  else if ((DIR_P (0) | DIR_P (1))
+	   || (parent
+	       && (! S_ISREG (cmp.file[0].stat.st_mode)
+		   || ! S_ISREG (cmp.file[1].stat.st_mode))))
+    {
+      if (cmp.file[0].desc == NONEXISTENT || cmp.file[1].desc == NONEXISTENT)
+	{
+	  /* We have a subdirectory that exists only in one directory.  */
+
+	  if ((DIR_P (0) | DIR_P (1))
+	      && recursive
+	      && (new_file
+		  || (unidirectional_new_file
+		      && cmp.file[0].desc == NONEXISTENT)))
+	    status = diff_dirs (&cmp, compare_files);
+	  else
+	    {
+	      char const *dir;
+
+	      /* PARENT must be non-NULL here.  */
+	      assert (parent);
+	      dir = parent->file[cmp.file[0].desc == NONEXISTENT].name;
+
+	      /* See POSIX 1003.1-2001 for this format.  */
+	      message ("Only in %s: %s\n", dir, name0);
+
+	      status = EXIT_FAILURE;
+	    }
+	}
+      else
+	{
+	  /* We have two files that are not to be compared.  */
+
+	  /* See POSIX 1003.1-2001 for this format.  */
+	  message5 ("File %s is a %s while file %s is a %s\n",
+		    file_label[0] ? file_label[0] : cmp.file[0].name,
+		    file_type (&cmp.file[0].stat),
+		    file_label[1] ? file_label[1] : cmp.file[1].name,
+		    file_type (&cmp.file[1].stat));
+
+	  /* This is a difference.  */
+	  status = EXIT_FAILURE;
+	}
+    }
+  else if (files_can_be_treated_as_binary
+	   && S_ISREG (cmp.file[0].stat.st_mode)
+	   && S_ISREG (cmp.file[1].stat.st_mode)
+	   && cmp.file[0].stat.st_size != cmp.file[1].stat.st_size)
+    {
+      message ("Files %s and %s differ\n",
+	       file_label[0] ? file_label[0] : cmp.file[0].name,
+	       file_label[1] ? file_label[1] : cmp.file[1].name);
+      status = EXIT_FAILURE;
+    }
+  else
+    {
+      /* Both exist and neither is a directory.  */
+
+      /* Open the files and record their descriptors.  */
+
+      int oflags = O_RDONLY | (binary ? O_BINARY : 0);
+
+      if (cmp.file[0].desc == UNOPENED)
+	if ((cmp.file[0].desc = open (cmp.file[0].name, oflags, 0)) < 0)
+	  {
+	    perror_with_name (cmp.file[0].name);
+	    status = EXIT_TROUBLE;
+	  }
+      if (cmp.file[1].desc == UNOPENED)
+	{
+	  if (same_files)
+	    cmp.file[1].desc = cmp.file[0].desc;
+	  else if ((cmp.file[1].desc = open (cmp.file[1].name, oflags, 0)) < 0)
+	    {
+	      perror_with_name (cmp.file[1].name);
+	      status = EXIT_TROUBLE;
+	    }
+	}
+
+      /* Compare the files, if no error was found.  */
+
+      if (status == EXIT_SUCCESS)
+	status = diff_2_files (&cmp);
+
+      /* Close the file descriptors.  */
+
+      if (0 <= cmp.file[0].desc && close (cmp.file[0].desc) != 0)
+	{
+	  perror_with_name (cmp.file[0].name);
+	  status = EXIT_TROUBLE;
+	}
+      if (0 <= cmp.file[1].desc && cmp.file[0].desc != cmp.file[1].desc
+	  && close (cmp.file[1].desc) != 0)
+	{
+	  perror_with_name (cmp.file[1].name);
+	  status = EXIT_TROUBLE;
+	}
+    }
+
+  /* Now the comparison has been done, if no error prevented it,
+     and STATUS is the value this function will return.  */
+
+  if (status == EXIT_SUCCESS)
+    {
+      if (report_identical_files && !DIR_P (0))
+	message ("Files %s and %s are identical\n",
+		 file_label[0] ? file_label[0] : cmp.file[0].name,
+		 file_label[1] ? file_label[1] : cmp.file[1].name);
+    }
+  else
+    {
+      /* Flush stdout so that the user sees differences immediately.
+	 This can hurt performance, unfortunately.  */
+      if (fflush (stdout) != 0)
+	pfatal_with_name (_("standard output"));
+    }
+
+  free (free0);
+  free (free1);
+
+  return status;
+}
diff --git a/src/diff.h b/src/diff.h
new file mode 100644
index 0000000..578c4ea
--- /dev/null
+++ b/src/diff.h
@@ -0,0 +1,388 @@
+/* Shared definitions for GNU DIFF
+
+   Copyright (C) 1988-1989, 1991-1995, 1998, 2001-2002, 2004, 2009-2011 Free
+   Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "system.h"
+#include <regex.h>
+#include <stdio.h>
+#include <unlocked-io.h>
+
+/* What kind of changes a hunk contains.  */
+enum changes
+{
+  /* No changes: lines common to both files.  */
+  UNCHANGED,
+
+  /* Deletes only: lines taken from just the first file.  */
+  OLD,
+
+  /* Inserts only: lines taken from just the second file.  */
+  NEW,
+
+  /* Both deletes and inserts: a hunk containing both old and new lines.  */
+  CHANGED
+};
+
+/* Variables for command line options */
+
+#ifndef GDIFF_MAIN
+# define XTERN extern
+#else
+# define XTERN
+#endif
+
+enum output_style
+{
+  /* No output style specified.  */
+  OUTPUT_UNSPECIFIED,
+
+  /* Default output style.  */
+  OUTPUT_NORMAL,
+
+  /* Output the differences with lines of context before and after (-c).  */
+  OUTPUT_CONTEXT,
+
+  /* Output the differences in a unified context diff format (-u).  */
+  OUTPUT_UNIFIED,
+
+  /* Output the differences as commands suitable for `ed' (-e).  */
+  OUTPUT_ED,
+
+  /* Output the diff as a forward ed script (-f).  */
+  OUTPUT_FORWARD_ED,
+
+  /* Like -f, but output a count of changed lines in each "command" (-n).  */
+  OUTPUT_RCS,
+
+  /* Output merged #ifdef'd file (-D).  */
+  OUTPUT_IFDEF,
+
+  /* Output sdiff style (-y).  */
+  OUTPUT_SDIFF
+};
+
+/* True for output styles that are robust,
+   i.e. can handle a file that ends in a non-newline.  */
+#define ROBUST_OUTPUT_STYLE(S) ((S) != OUTPUT_ED && (S) != OUTPUT_FORWARD_ED)
+
+XTERN enum output_style output_style;
+
+/* Nonzero if output cannot be generated for identical files.  */
+XTERN bool no_diff_means_no_output;
+
+/* Number of lines of context to show in each set of diffs.
+   This is zero when context is not to be shown.  */
+XTERN lin context;
+
+/* Consider all files as text files (-a).
+   Don't interpret codes over 0177 as implying a "binary file".  */
+XTERN bool text;
+
+/* Number of lines to keep in identical prefix and suffix.  */
+XTERN lin horizon_lines;
+
+/* The significance of white space during comparisons.  */
+enum DIFF_white_space
+{
+  /* All white space is significant (the default).  */
+  IGNORE_NO_WHITE_SPACE,
+
+  /* Ignore changes due to tab expansion (-E).  */
+  IGNORE_TAB_EXPANSION,
+
+  /* Ignore changes in trailing horizontal white space (-Z).  */
+  IGNORE_TRAILING_SPACE,
+
+  /* IGNORE_TAB_EXPANSION and IGNORE_TRAILING_SPACE are a special case
+     because they are independent and can be ORed together, yielding
+     IGNORE_TAB_EXPANSION_AND_TRAILING_SPACE.  */
+  IGNORE_TAB_EXPANSION_AND_TRAILING_SPACE,
+
+  /* Ignore changes in horizontal white space (-b).  */
+  IGNORE_SPACE_CHANGE,
+
+  /* Ignore all horizontal white space (-w).  */
+  IGNORE_ALL_SPACE
+};
+XTERN enum DIFF_white_space ignore_white_space;
+
+/* Ignore changes that affect only blank lines (-B).  */
+XTERN bool ignore_blank_lines;
+
+/* Files can be compared byte-by-byte, as if they were binary.
+   This depends on various options.  */
+XTERN bool files_can_be_treated_as_binary;
+
+/* Ignore differences in case of letters (-i).  */
+XTERN bool ignore_case;
+
+/* Ignore differences in case of letters in file names.  */
+XTERN bool ignore_file_name_case;
+
+/* File labels for `-c' output headers (--label).  */
+XTERN char *file_label[2];
+
+/* Regexp to identify function-header lines (-F).  */
+XTERN struct re_pattern_buffer function_regexp;
+
+/* Ignore changes that affect only lines matching this regexp (-I).  */
+XTERN struct re_pattern_buffer ignore_regexp;
+
+/* Say only whether files differ, not how (-q).  */
+XTERN bool brief;
+
+/* Expand tabs in the output so the text lines up properly
+   despite the characters added to the front of each line (-t).  */
+XTERN bool expand_tabs;
+
+/* Number of columns between tab stops.  */
+XTERN size_t tabsize;
+
+/* Use a tab in the output, rather than a space, before the text of an
+   input line, so as to keep the proper alignment in the input line
+   without changing the characters in it (-T).  */
+XTERN bool initial_tab;
+
+/* Do not output an initial space or tab before the text of an empty line.  */
+XTERN bool suppress_blank_empty;
+
+/* Remove trailing carriage returns from input.  */
+XTERN bool strip_trailing_cr;
+
+/* In directory comparison, specify file to start with (-S).
+   This is used for resuming an aborted comparison.
+   All file names less than this name are ignored.  */
+XTERN char const *starting_file;
+
+/* Pipe each file's output through pr (-l).  */
+XTERN bool paginate;
+
+/* Line group formats for unchanged, old, new, and changed groups.  */
+XTERN char const *group_format[CHANGED + 1];
+
+/* Line formats for unchanged, old, and new lines.  */
+XTERN char const *line_format[NEW + 1];
+
+/* If using OUTPUT_SDIFF print extra information to help the sdiff filter.  */
+XTERN bool sdiff_merge_assist;
+
+/* Tell OUTPUT_SDIFF to show only the left version of common lines.  */
+XTERN bool left_column;
+
+/* Tell OUTPUT_SDIFF to not show common lines.  */
+XTERN bool suppress_common_lines;
+
+/* The half line width and column 2 offset for OUTPUT_SDIFF.  */
+XTERN size_t sdiff_half_width;
+XTERN size_t sdiff_column2_offset;
+
+/* String containing all the command options diff received,
+   with spaces between and at the beginning but none at the end.
+   If there were no options given, this string is empty.  */
+XTERN char *switch_string;
+
+/* Use heuristics for better speed with large files with a small
+   density of changes.  */
+XTERN bool speed_large_files;
+
+/* Patterns that match file names to be excluded.  */
+XTERN struct exclude *excluded;
+
+/* Don't discard lines.  This makes things slower (sometimes much
+   slower) but will find a guaranteed minimal set of changes.  */
+XTERN bool minimal;
+
+/* The strftime format to use for time strings.  */
+XTERN char const *time_format;
+
+/* The result of comparison is an "edit script": a chain of `struct change'.
+   Each `struct change' represents one place where some lines are deleted
+   and some are inserted.
+
+   LINE0 and LINE1 are the first affected lines in the two files (origin 0).
+   DELETED is the number of lines deleted here from file 0.
+   INSERTED is the number of lines inserted here in file 1.
+
+   If DELETED is 0 then LINE0 is the number of the line before
+   which the insertion was done; vice versa for INSERTED and LINE1.  */
+
+struct change
+{
+  struct change *link;		/* Previous or next edit command  */
+  lin inserted;			/* # lines of file 1 changed here.  */
+  lin deleted;			/* # lines of file 0 changed here.  */
+  lin line0;			/* Line number of 1st deleted line.  */
+  lin line1;			/* Line number of 1st inserted line.  */
+  bool ignore;			/* Flag used in context.c.  */
+};
+
+/* Structures that describe the input files.  */
+
+/* Data on one input file being compared.  */
+
+struct file_data {
+    int             desc;	/* File descriptor  */
+    char const      *name;	/* File name  */
+    struct stat     stat;	/* File status */
+
+    /* Buffer in which text of file is read.  */
+    word *buffer;
+
+    /* Allocated size of buffer, in bytes.  Always a multiple of
+       sizeof *buffer.  */
+    size_t bufsize;
+
+    /* Number of valid bytes now in the buffer.  */
+    size_t buffered;
+
+    /* Array of pointers to lines in the file.  */
+    char const **linbuf;
+
+    /* linbuf_base <= buffered_lines <= valid_lines <= alloc_lines.
+       linebuf[linbuf_base ... buffered_lines - 1] are possibly differing.
+       linebuf[linbuf_base ... valid_lines - 1] contain valid data.
+       linebuf[linbuf_base ... alloc_lines - 1] are allocated.  */
+    lin linbuf_base, buffered_lines, valid_lines, alloc_lines;
+
+    /* Pointer to end of prefix of this file to ignore when hashing.  */
+    char const *prefix_end;
+
+    /* Count of lines in the prefix.
+       There are this many lines in the file before linbuf[0].  */
+    lin prefix_lines;
+
+    /* Pointer to start of suffix of this file to ignore when hashing.  */
+    char const *suffix_begin;
+
+    /* Vector, indexed by line number, containing an equivalence code for
+       each line.  It is this vector that is actually compared with that
+       of another file to generate differences.  */
+    lin *equivs;
+
+    /* Vector, like the previous one except that
+       the elements for discarded lines have been squeezed out.  */
+    lin *undiscarded;
+
+    /* Vector mapping virtual line numbers (not counting discarded lines)
+       to real ones (counting those lines).  Both are origin-0.  */
+    lin *realindexes;
+
+    /* Total number of nondiscarded lines.  */
+    lin nondiscarded_lines;
+
+    /* Vector, indexed by real origin-0 line number,
+       containing 1 for a line that is an insertion or a deletion.
+       The results of comparison are stored here.  */
+    char *changed;
+
+    /* 1 if file ends in a line with no final newline.  */
+    bool missing_newline;
+
+    /* 1 if at end of file.  */
+    bool eof;
+
+    /* 1 more than the maximum equivalence value used for this or its
+       sibling file.  */
+    lin equiv_max;
+};
+
+/* The file buffer, considered as an array of bytes rather than
+   as an array of words.  */
+#define FILE_BUFFER(f) ((char *) (f)->buffer)
+
+/* Data on two input files being compared.  */
+
+struct comparison
+  {
+    struct file_data file[2];
+    struct comparison const *parent;  /* parent, if a recursive comparison */
+  };
+
+/* Describe the two files currently being compared.  */
+
+XTERN struct file_data files[2];
+
+/* Stdio stream to output diffs to.  */
+
+XTERN FILE *outfile;
+
+/* Declare various functions.  */
+
+/* analyze.c */
+extern int diff_2_files (struct comparison *);
+
+/* context.c */
+extern void print_context_header (struct file_data[], bool);
+extern void print_context_script (struct change *, bool);
+
+/* dir.c */
+extern int diff_dirs (struct comparison const *,
+                      int (*) (struct comparison const *,
+                               char const *, char const *));
+extern char *find_dir_file_pathname (char const *, char const *);
+
+/* ed.c */
+extern void print_ed_script (struct change *);
+extern void pr_forward_ed_script (struct change *);
+
+/* ifdef.c */
+extern void print_ifdef_script (struct change *);
+
+/* io.c */
+extern void file_block_read (struct file_data *, size_t);
+extern bool read_files (struct file_data[], bool);
+
+/* normal.c */
+extern void print_normal_script (struct change *);
+
+/* rcs.c */
+extern void print_rcs_script (struct change *);
+
+/* side.c */
+extern void print_sdiff_script (struct change *);
+
+/* util.c */
+extern char const change_letter[4];
+extern char const pr_program[];
+extern char *concat (char const *, char const *, char const *);
+extern bool lines_differ (char const *, char const *);
+extern lin translate_line_number (struct file_data const *, lin);
+extern struct change *find_change (struct change *);
+extern struct change *find_reverse_change (struct change *);
+extern void *zalloc (size_t);
+extern enum changes analyze_hunk (struct change *, lin *, lin *, lin *, lin *);
+extern void begin_output (void);
+extern void debug_script (struct change *);
+extern void fatal (char const *) __attribute__((noreturn));
+extern void finish_output (void);
+extern void message (char const *, char const *, char const *);
+extern void message5 (char const *, char const *, char const *,
+                      char const *, char const *);
+extern void output_1_line (char const *, char const *, char const *,
+                           char const *);
+extern void perror_with_name (char const *);
+extern void pfatal_with_name (char const *) __attribute__((noreturn));
+extern void print_1_line (char const *, char const * const *);
+extern void print_message_queue (void);
+extern void print_number_range (char, struct file_data *, lin, lin);
+extern void print_script (struct change *, struct change * (*) (struct change *),
+                          void (*) (struct change *));
+extern void setup_output (char const *, char const *, bool);
+extern void translate_range (struct file_data const *, lin, lin,
+                             long int *, long int *);
diff --git a/src/diff3.c b/src/diff3.c
new file mode 100644
index 0000000..343c055
--- /dev/null
+++ b/src/diff3.c
@@ -0,0 +1,1765 @@
+/* diff3 - compare three files line by line
+
+   Copyright (C) 1988-1989, 1992-1996, 1998, 2001-2002, 2004, 2006, 2009-2011
+   Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "system.h"
+#include "paths.h"
+
+#include <stdio.h>
+#include <unlocked-io.h>
+
+#include <c-stack.h>
+#include <cmpbuf.h>
+#include <error.h>
+#include <exitfail.h>
+#include <file-type.h>
+#include <getopt.h>
+#include <progname.h>
+#include <sh-quote.h>
+#include <version-etc.h>
+#include <xalloc.h>
+#include <xfreopen.h>
+
+/* The official name of this program (e.g., no `g' prefix).  */
+#define PROGRAM_NAME "diff3"
+
+#define AUTHORS \
+  proper_name ("Randy Smith")
+
+/* Internal data structures and macros for the diff3 program; includes
+   data structures for both diff3 diffs and normal diffs.  */
+
+/* Different files within a three way diff.  */
+#define	FILE0	0
+#define	FILE1	1
+#define	FILE2	2
+
+/* A three way diff is built from two two-way diffs; the file which
+   the two two-way diffs share is:  */
+#define	FILEC	FILE2
+
+/* Different files within a two way diff.
+   FC is the common file, FO the other file.  */
+#define FO 0
+#define FC 1
+
+/* The ranges are indexed by */
+#define	RANGE_START	0
+#define	RANGE_END	1
+
+enum diff_type {
+  ERROR,			/* Should not be used */
+  ADD,				/* Two way diff add */
+  CHANGE,			/* Two way diff change */
+  DELETE,			/* Two way diff delete */
+  DIFF_ALL,			/* All three are different */
+  DIFF_1ST,			/* Only the first is different */
+  DIFF_2ND,			/* Only the second */
+  DIFF_3RD			/* Only the third */
+};
+
+/* Two way diff */
+struct diff_block {
+  lin ranges[2][2];		/* Ranges are inclusive */
+  char **lines[2];		/* The actual lines (may contain nulls) */
+  size_t *lengths[2];		/* Line lengths (including newlines, if any) */
+  struct diff_block *next;
+};
+
+/* Three way diff */
+
+struct diff3_block {
+  enum diff_type correspond;	/* Type of diff */
+  lin ranges[3][2];		/* Ranges are inclusive */
+  char **lines[3];		/* The actual lines (may contain nulls) */
+  size_t *lengths[3];		/* Line lengths (including newlines, if any) */
+  struct diff3_block *next;
+};
+
+/* Access the ranges on a diff block.  */
+#define	D_LOWLINE(diff, filenum)	\
+  ((diff)->ranges[filenum][RANGE_START])
+#define	D_HIGHLINE(diff, filenum)	\
+  ((diff)->ranges[filenum][RANGE_END])
+#define	D_NUMLINES(diff, filenum)	\
+  (D_HIGHLINE (diff, filenum) - D_LOWLINE (diff, filenum) + 1)
+
+/* Access the line numbers in a file in a diff by relative line
+   numbers (i.e. line number within the diff itself).  Note that these
+   are lvalues and can be used for assignment.  */
+#define	D_RELNUM(diff, filenum, linenum)	\
+  ((diff)->lines[filenum][linenum])
+#define	D_RELLEN(diff, filenum, linenum)	\
+  ((diff)->lengths[filenum][linenum])
+
+/* And get at them directly, when that should be necessary.  */
+#define	D_LINEARRAY(diff, filenum)	\
+  ((diff)->lines[filenum])
+#define	D_LENARRAY(diff, filenum)	\
+  ((diff)->lengths[filenum])
+
+/* Next block.  */
+#define	D_NEXT(diff)	((diff)->next)
+
+/* Access the type of a diff3 block.  */
+#define	D3_TYPE(diff)	((diff)->correspond)
+
+/* Line mappings based on diffs.  The first maps off the top of the
+   diff, the second off of the bottom.  */
+#define	D_HIGH_MAPLINE(diff, fromfile, tofile, linenum)	\
+  ((linenum)						\
+   - D_HIGHLINE ((diff), (fromfile))			\
+   + D_HIGHLINE ((diff), (tofile)))
+
+#define	D_LOW_MAPLINE(diff, fromfile, tofile, linenum)	\
+  ((linenum)						\
+   - D_LOWLINE ((diff), (fromfile))			\
+   + D_LOWLINE ((diff), (tofile)))
+
+/* Options variables for flags set on command line.  */
+
+/* If nonzero, treat all files as text files, never as binary.  */
+static bool text;
+
+/* Remove trailing carriage returns from input.  */
+static bool strip_trailing_cr;
+
+/* If nonzero, write out an ed script instead of the standard diff3 format.  */
+static bool edscript;
+
+/* If nonzero, in the case of overlapping diffs (type DIFF_ALL),
+   preserve the lines which would normally be deleted from
+   file 1 with a special flagging mechanism.  */
+static bool flagging;
+
+/* Use a tab to align output lines (-T).  */
+static bool initial_tab;
+
+/* If nonzero, do not output information for overlapping diffs.  */
+static bool simple_only;
+
+/* If nonzero, do not output information for non-overlapping diffs.  */
+static bool overlap_only;
+
+/* If nonzero, show information for DIFF_2ND diffs.  */
+static bool show_2nd;
+
+/* If nonzero, include `:wq' at the end of the script
+   to write out the file being edited.   */
+static bool finalwrite;
+
+/* If nonzero, output a merged file.  */
+static bool merge;
+
+static char *read_diff (char const *, char const *, char **);
+static char *scan_diff_line (char *, char **, size_t *, char *, char);
+static enum diff_type process_diff_control (char **, struct diff_block *);
+static bool compare_line_list (char * const[], size_t const[], char * const[], size_t const[], lin);
+static bool copy_stringlist (char * const[], size_t const[], char *[], size_t[], lin);
+static bool output_diff3_edscript (FILE *, struct diff3_block *, int const[3], int const[3], char const *, char const *, char const *);
+static bool output_diff3_merge (FILE *, FILE *, struct diff3_block *, int const[3], int const[3], char const *, char const *, char const *);
+static struct diff3_block *create_diff3_block (lin, lin, lin, lin, lin, lin);
+static struct diff3_block *make_3way_diff (struct diff_block *, struct diff_block *);
+static struct diff3_block *reverse_diff3_blocklist (struct diff3_block *);
+static struct diff3_block *using_to_diff3_block (struct diff_block *[2], struct diff_block *[2], int, int, struct diff3_block const *);
+static struct diff_block *process_diff (char const *, char const *, struct diff_block **);
+static void check_stdout (void);
+static void fatal (char const *) __attribute__((noreturn));
+static void output_diff3 (FILE *, struct diff3_block *, int const[3], int const[3]);
+static void perror_with_exit (char const *) __attribute__((noreturn));
+static void try_help (char const *, char const *) __attribute__((noreturn));
+static void usage (void);
+
+static char const *diff_program = DEFAULT_DIFF_PROGRAM;
+
+/* Values for long options that do not have single-letter equivalents.  */
+enum
+{
+  DIFF_PROGRAM_OPTION = CHAR_MAX + 1,
+  HELP_OPTION,
+  STRIP_TRAILING_CR_OPTION
+};
+
+static struct option const longopts[] =
+{
+  {"diff-program", 1, 0, DIFF_PROGRAM_OPTION},
+  {"easy-only", 0, 0, '3'},
+  {"ed", 0, 0, 'e'},
+  {"help", 0, 0, HELP_OPTION},
+  {"initial-tab", 0, 0, 'T'},
+  {"label", 1, 0, 'L'},
+  {"merge", 0, 0, 'm'},
+  {"overlap-only", 0, 0, 'x'},
+  {"show-all", 0, 0, 'A'},
+  {"show-overlap", 0, 0, 'E'},
+  {"strip-trailing-cr", 0, 0, STRIP_TRAILING_CR_OPTION},
+  {"text", 0, 0, 'a'},
+  {"version", 0, 0, 'v'},
+  {0, 0, 0, 0}
+};
+
+int
+main (int argc, char **argv)
+{
+  int c, i;
+  int common;
+  int mapping[3];
+  int rev_mapping[3];
+  int incompat = 0;
+  bool conflicts_found;
+  struct diff_block *thread0, *thread1, *last_block;
+  struct diff3_block *diff3;
+  int tag_count = 0;
+  char *tag_strings[3];
+  char *commonname;
+  char **file;
+  struct stat statb;
+
+  exit_failure = EXIT_TROUBLE;
+  initialize_main (&argc, &argv);
+  set_program_name (argv[0]);
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+  c_stack_action (0);
+
+  while ((c = getopt_long (argc, argv, "aeimvx3AEL:TX", longopts, 0)) != -1)
+    {
+      switch (c)
+	{
+	case 'a':
+	  text = true;
+	  break;
+	case 'A':
+	  show_2nd = true;
+	  flagging = true;
+	  incompat++;
+	  break;
+	case 'x':
+	  overlap_only = true;
+	  incompat++;
+	  break;
+	case '3':
+	  simple_only = true;
+	  incompat++;
+	  break;
+	case 'i':
+	  finalwrite = true;
+	  break;
+	case 'm':
+	  merge = true;
+	  break;
+	case 'X':
+	  overlap_only = true;
+	  /* Fall through.  */
+	case 'E':
+	  flagging = true;
+	  /* Fall through.  */
+	case 'e':
+	  incompat++;
+	  break;
+	case 'T':
+	  initial_tab = true;
+	  break;
+	case STRIP_TRAILING_CR_OPTION:
+	  strip_trailing_cr = true;
+	  break;
+	case 'v':
+	  version_etc (stdout, PROGRAM_NAME, PACKAGE_NAME, Version,
+		       AUTHORS, (char *) NULL);
+	  check_stdout ();
+	  return EXIT_SUCCESS;
+	case DIFF_PROGRAM_OPTION:
+	  diff_program = optarg;
+	  break;
+	case HELP_OPTION:
+	  usage ();
+	  check_stdout ();
+	  return EXIT_SUCCESS;
+	case 'L':
+	  /* Handle up to three -L options.  */
+	  if (tag_count < 3)
+	    {
+	      tag_strings[tag_count++] = optarg;
+	      break;
+	    }
+	  try_help ("too many file label options", 0);
+	default:
+	  try_help (0, 0);
+	}
+    }
+
+  edscript = incompat & ~merge;  /* -AeExX3 without -m implies ed script.  */
+  show_2nd |= ~incompat & merge;  /* -m without -AeExX3 implies -A.  */
+  flagging |= ~incompat & merge;
+
+  if (incompat > 1  /* Ensure at most one of -AeExX3.  */
+      || finalwrite & merge /* -i -m would rewrite input file.  */
+      || (tag_count && ! flagging)) /* -L requires one of -AEX.  */
+    try_help ("incompatible options", 0);
+
+  if (argc - optind != 3)
+    {
+      if (argc - optind < 3)
+	try_help ("missing operand after `%s'", argv[argc - 1]);
+      else
+	try_help ("extra operand `%s'", argv[optind + 3]);
+    }
+
+  file = &argv[optind];
+
+  for (i = tag_count; i < 3; i++)
+    tag_strings[i] = file[i];
+
+  /* Always compare file1 to file2, even if file2 is "-".
+     This is needed for -mAeExX3.  Using the file0 as
+     the common file would produce wrong results, because if the
+     file0-file1 diffs didn't line up with the file0-file2 diffs
+     (which is entirely possible since we don't use diff's -n option),
+     diff3 might report phantom changes from file1 to file2.
+
+     Also, try to compare file0 to file1, because this is where
+     changes are expected to come from.  Diffing between these pairs
+     of files is more likely to avoid phantom changes from file0 to file1.
+
+     Historically, the default common file was file2, so some older
+     applications (e.g. Emacs ediff) used file2 as the ancestor.  So,
+     for compatibility, if this is a 3-way diff (not a merge or
+     edscript), prefer file2 as the common file.  */
+
+  common = 2 - (edscript | merge);
+
+  if (STREQ (file[common], "-"))
+    {
+      /* Sigh.  We've got standard input as the common file.  We can't
+	 call diff twice on stdin.  Use the other arg as the common
+	 file instead.  */
+      common = 3 - common;
+      if (STREQ (file[0], "-") || STREQ (file[common], "-"))
+	fatal ("`-' specified for more than one input file");
+    }
+
+  mapping[0] = 0;
+  mapping[1] = 3 - common;
+  mapping[2] = common;
+
+  for (i = 0; i < 3; i++)
+    rev_mapping[mapping[i]] = i;
+
+  for (i = 0; i < 3; i++)
+    if (! STREQ (file[i], "-"))
+      {
+	if (stat (file[i], &statb) < 0)
+	  perror_with_exit (file[i]);
+	else if (S_ISDIR (statb.st_mode))
+	  error (EXIT_TROUBLE, EISDIR, "%s", file[i]);
+      }
+
+#ifdef SIGCHLD
+  /* System V fork+wait does not work if SIGCHLD is ignored.  */
+  signal (SIGCHLD, SIG_DFL);
+#endif
+
+  /* Invoke diff twice on two pairs of input files, combine the two
+     diffs, and output them.  */
+
+  commonname = file[rev_mapping[FILEC]];
+  thread1 = process_diff (file[rev_mapping[FILE1]], commonname, &last_block);
+  thread0 = process_diff (file[rev_mapping[FILE0]], commonname, &last_block);
+  diff3 = make_3way_diff (thread0, thread1);
+  if (edscript)
+    conflicts_found
+      = output_diff3_edscript (stdout, diff3, mapping, rev_mapping,
+			       tag_strings[0], tag_strings[1], tag_strings[2]);
+  else if (merge)
+    {
+      xfreopen (file[rev_mapping[FILE0]], "r", stdin);
+      conflicts_found
+	= output_diff3_merge (stdin, stdout, diff3, mapping, rev_mapping,
+			      tag_strings[0], tag_strings[1], tag_strings[2]);
+      if (ferror (stdin))
+	fatal ("read failed");
+    }
+  else
+    {
+      output_diff3 (stdout, diff3, mapping, rev_mapping);
+      conflicts_found = false;
+    }
+
+  check_stdout ();
+  exit (conflicts_found);
+  return conflicts_found;
+}
+
+static void
+try_help (char const *reason_msgid, char const *operand)
+{
+  if (reason_msgid)
+    error (0, 0, _(reason_msgid), operand);
+  error (EXIT_TROUBLE, 0,
+	 _("Try `%s --help' for more information."), program_name);
+  abort ();
+}
+
+static void
+check_stdout (void)
+{
+  if (ferror (stdout))
+    fatal ("write failed");
+  else if (fclose (stdout) != 0)
+    perror_with_exit (_("standard output"));
+}
+
+static char const * const option_help_msgid[] = {
+  N_("-A, --show-all              output all changes, bracketing conflicts"),
+  "",
+  N_("-e, --ed                    output ed script incorporating changes\n"
+     "                                from OLDFILE to YOURFILE into MYFILE"),
+  N_("-E, --show-overlap          like -e, but bracket conflicts"),
+  N_("-3, --easy-only             like -e, but incorporate only nonoverlapping changes"),
+  N_("-x, --overlap-only          like -e, but incorporate only overlapping changes"),
+  N_("-X                          like -x, but bracket conflicts"),
+  N_("-i                          append `w' and `q' commands to ed scripts"),
+  "",
+  N_("-m, --merge                 output actual merged file, according to\n"
+     "                                -A if no other options are given"),
+  "",
+  N_("-a, --text                  treat all files as text"),
+  N_("    --strip-trailing-cr     strip trailing carriage return on input"),
+  N_("-T, --initial-tab           make tabs line up by prepending a tab"),
+  N_("    --diff-program=PROGRAM  use PROGRAM to compare files"),
+  N_("-L, --label=LABEL           use LABEL instead of file name\n"
+     "                                (can be repeated up to three times)"),
+  "",
+  N_("    --help                  display this help and exit"),
+  N_("-v, --version               output version information and exit"),
+  0
+};
+
+static void
+usage (void)
+{
+  char const * const *p;
+
+  printf (_("Usage: %s [OPTION]... MYFILE OLDFILE YOURFILE\n"),
+	  program_name);
+  printf ("%s\n\n", _("Compare three files line by line."));
+
+  fputs (_("\
+Mandatory arguments to long options are mandatory for short options too.\n\
+"), stdout);
+  for (p = option_help_msgid;  *p;  p++)
+    if (**p)
+      printf ("  %s\n", _(*p));
+    else
+      putchar ('\n');
+  fputs (_("\n\
+The default output format is a somewhat human-readable representation of\n\
+the changes.\n\
+\n\
+The -e, -E, -x, -X (and corresponding long) options cause an ed script\n\
+to be output instead of the default.\n\
+\n\
+Finally, the -m (--merge) option causes diff3 to do the merge internally\n\
+and output the actual merged file.  For unusual input, this is more\n\
+robust than using ed.\n"), stdout);
+  printf ("\n%s\n%s\n",
+	  _("If a FILE is `-', read standard input."),
+	  _("Exit status is 0 if successful, 1 if conflicts, 2 if trouble."));
+  emit_bug_reporting_address ();
+}
+
+/* Combine the two diffs together into one.
+   Here is the algorithm:
+
+     File2 is shared in common between the two diffs.
+     Diff02 is the diff between 0 and 2.
+     Diff12 is the diff between 1 and 2.
+
+	1) Find the range for the first block in File2.
+	    a) Take the lowest of the two ranges (in File2) in the two
+	       current blocks (one from each diff) as being the low
+	       water mark.  Assign the upper end of this block as
+	       being the high water mark and move the current block up
+	       one.  Mark the block just moved over as to be used.
+	    b) Check the next block in the diff that the high water
+	       mark is *not* from.
+
+	       *If* the high water mark is above
+	       the low end of the range in that block,
+
+		   mark that block as to be used and move the current
+		   block up.  Set the high water mark to the max of
+		   the high end of this block and the current.  Repeat b.
+
+	 2) Find the corresponding ranges in File0 (from the blocks
+	    in diff02; line per line outside of diffs) and in File1.
+	    Create a diff3_block, reserving space as indicated by the ranges.
+
+	 3) Copy all of the pointers for file2 in.  At least for now,
+	    do memcmp's between corresponding strings in the two diffs.
+
+	 4) Copy all of the pointers for file0 and 1 in.  Get what is
+	    needed from file2 (when there isn't a diff block, it's
+	    identical to file2 within the range between diff blocks).
+
+	 5) If the diff blocks used came from only one of the two
+	    strings of diffs, then that file (i.e. the one other than
+	    the common file in that diff) is the odd person out.  If
+	    diff blocks are used from both sets, check to see if files
+	    0 and 1 match:
+
+		Same number of lines?  If so, do a set of memcmp's (if
+	    a memcmp matches; copy the pointer over; it'll be easier
+	    later during comparisons).  If they match, 0 & 1 are the
+	    same.  If not, all three different.
+
+     Then do it again, until the blocks are exhausted.  */
+
+
+/* Make a three way diff (chain of diff3_block's) from two two way
+   diffs (chains of diff_block's).  Assume that each of the two diffs
+   passed are onto the same file (i.e. that each of the diffs were
+   made "to" the same file).  Return a three way diff pointer with
+   numbering FILE0 = the other file in diff02, FILE1 = the other file
+   in diff12, and FILEC = the common file.  */
+
+static struct diff3_block *
+make_3way_diff (struct diff_block *thread0, struct diff_block *thread1)
+{
+  /* Work on the two diffs passed to it as threads.  Thread number 0
+     is diff02, thread number 1 is diff12.  USING is the base of the
+     list of blocks to be used to construct each block of the three
+     way diff; if no blocks from a particular thread are to be used,
+     that element of USING is 0.  LAST_USING contains the last
+     elements on each of the using lists.
+
+     HIGH_WATER_MARK is the highest line number in the common file
+     described in any of the diffs in either of the USING lists.
+     HIGH_WATER_THREAD names the thread.  Similarly BASE_WATER_MARK
+     and BASE_WATER_THREAD describe the lowest line number in the
+     common file described in any of the diffs in either of the USING
+     lists.  HIGH_WATER_DIFF is the diff from which the
+     HIGH_WATER_MARK was taken.
+
+     HIGH_WATER_DIFF should always be equal to
+     LAST_USING[HIGH_WATER_THREAD].  OTHER_DIFF is the next diff to
+     check for higher water, and should always be equal to
+     CURRENT[HIGH_WATER_THREAD ^ 1].  OTHER_THREAD is the thread in
+     which the OTHER_DIFF is, and hence should always be equal to
+     HIGH_WATER_THREAD ^ 1.
+
+     LAST_DIFF is the last diff block produced by this routine, for
+     line correspondence purposes between that diff and the one
+     currently being worked on.  It is ZERO_DIFF before any blocks
+     have been created.  */
+
+  struct diff_block *using[2];
+  struct diff_block *last_using[2];
+  struct diff_block *current[2];
+
+  lin high_water_mark;
+
+  int high_water_thread;
+  int base_water_thread;
+  int other_thread;
+
+  struct diff_block *high_water_diff;
+  struct diff_block *other_diff;
+
+  struct diff3_block *result;
+  struct diff3_block *tmpblock;
+  struct diff3_block **result_end;
+
+  struct diff3_block const *last_diff3;
+
+  static struct diff3_block const zero_diff3;
+
+  /* Initialization */
+  result = 0;
+  result_end = &result;
+  current[0] = thread0; current[1] = thread1;
+  last_diff3 = &zero_diff3;
+
+  /* Sniff up the threads until we reach the end */
+
+  while (current[0] || current[1])
+    {
+      using[0] = using[1] = last_using[0] = last_using[1] = 0;
+
+      /* Setup low and high water threads, diffs, and marks.  */
+      if (!current[0])
+	base_water_thread = 1;
+      else if (!current[1])
+	base_water_thread = 0;
+      else
+	base_water_thread =
+	  (D_LOWLINE (current[0], FC) > D_LOWLINE (current[1], FC));
+
+      high_water_thread = base_water_thread;
+
+      high_water_diff = current[high_water_thread];
+
+      high_water_mark = D_HIGHLINE (high_water_diff, FC);
+
+      /* Make the diff you just got info from into the using class */
+      using[high_water_thread]
+	= last_using[high_water_thread]
+	= high_water_diff;
+      current[high_water_thread] = high_water_diff->next;
+      last_using[high_water_thread]->next = 0;
+
+      /* And mark the other diff */
+      other_thread = high_water_thread ^ 0x1;
+      other_diff = current[other_thread];
+
+      /* Shuffle up the ladder, checking the other diff to see if it
+	 needs to be incorporated.  */
+      while (other_diff
+	     && D_LOWLINE (other_diff, FC) <= high_water_mark + 1)
+	{
+
+	  /* Incorporate this diff into the using list.  Note that
+	     this doesn't take it off the current list */
+	  if (using[other_thread])
+	    last_using[other_thread]->next = other_diff;
+	  else
+	    using[other_thread] = other_diff;
+	  last_using[other_thread] = other_diff;
+
+	  /* Take it off the current list.  Note that this following
+	     code assumes that other_diff enters it equal to
+	     current[high_water_thread ^ 0x1] */
+	  current[other_thread] = current[other_thread]->next;
+	  other_diff->next = 0;
+
+	  /* Set the high_water stuff
+	     If this comparison is equal, then this is the last pass
+	     through this loop; since diff blocks within a given
+	     thread cannot overlap, the high_water_mark will be
+	     *below* the range_start of either of the next diffs.  */
+
+	  if (high_water_mark < D_HIGHLINE (other_diff, FC))
+	    {
+	      high_water_thread ^= 1;
+	      high_water_mark = D_HIGHLINE (other_diff, FC);
+	    }
+
+	  /* Set the other diff */
+	  other_thread = high_water_thread ^ 0x1;
+	  other_diff = current[other_thread];
+	}
+
+      /* The using lists contain a list of all of the blocks to be
+	 included in this diff3_block.  Create it.  */
+
+      tmpblock = using_to_diff3_block (using, last_using,
+				       base_water_thread, high_water_thread,
+				       last_diff3);
+
+      if (!tmpblock)
+	fatal ("internal error: screwup in format of diff blocks");
+
+      /* Put it on the list.  */
+      *result_end = tmpblock;
+      result_end = &tmpblock->next;
+
+      /* Set up corresponding lines correctly.  */
+      last_diff3 = tmpblock;
+    }
+  return result;
+}
+
+/* Take two lists of blocks (from two separate diff threads) and put
+   them together into one diff3 block.  Return a pointer to this diff3
+   block or 0 for failure.
+
+   All arguments besides using are for the convenience of the routine;
+   they could be derived from the using array.  LAST_USING is a pair
+   of pointers to the last blocks in the using structure.  LOW_THREAD
+   and HIGH_THREAD tell which threads contain the lowest and highest
+   line numbers for File0.  LAST_DIFF3 contains the last diff produced
+   in the calling routine.  This is used for lines mappings that
+   would still be identical to the state that diff ended in.
+
+   A distinction should be made in this routine between the two diffs
+   that are part of a normal two diff block, and the three diffs that
+   are part of a diff3_block.  */
+
+static struct diff3_block *
+using_to_diff3_block (struct diff_block *using[2],
+		      struct diff_block *last_using[2],
+		      int low_thread, int high_thread,
+		      struct diff3_block const *last_diff3)
+{
+  lin low[2], high[2];
+  struct diff3_block *result;
+  struct diff_block *ptr;
+  int d;
+  lin i;
+
+  /* Find the range in the common file.  */
+  lin lowc = D_LOWLINE (using[low_thread], FC);
+  lin highc = D_HIGHLINE (last_using[high_thread], FC);
+
+  /* Find the ranges in the other files.
+     If using[d] is null, that means that the file to which that diff
+     refers is equivalent to the common file over this range.  */
+
+  for (d = 0; d < 2; d++)
+    if (using[d])
+      {
+	low[d] = D_LOW_MAPLINE (using[d], FC, FO, lowc);
+	high[d] = D_HIGH_MAPLINE (last_using[d], FC, FO, highc);
+      }
+    else
+      {
+	low[d] = D_HIGH_MAPLINE (last_diff3, FILEC, FILE0 + d, lowc);
+	high[d] = D_HIGH_MAPLINE (last_diff3, FILEC, FILE0 + d, highc);
+      }
+
+  /* Create a block with the appropriate sizes */
+  result = create_diff3_block (low[0], high[0], low[1], high[1], lowc, highc);
+
+  /* Copy information for the common file.
+     Return with a zero if any of the compares failed.  */
+
+  for (d = 0; d < 2; d++)
+    for (ptr = using[d]; ptr; ptr = D_NEXT (ptr))
+      {
+	lin result_offset = D_LOWLINE (ptr, FC) - lowc;
+
+	if (!copy_stringlist (D_LINEARRAY (ptr, FC),
+			      D_LENARRAY (ptr, FC),
+			      D_LINEARRAY (result, FILEC) + result_offset,
+			      D_LENARRAY (result, FILEC) + result_offset,
+			      D_NUMLINES (ptr, FC)))
+	  return 0;
+      }
+
+  /* Copy information for file d.  First deal with anything that might be
+     before the first diff.  */
+
+  for (d = 0; d < 2; d++)
+    {
+      struct diff_block *u = using[d];
+      lin lo = low[d], hi = high[d];
+
+      for (i = 0;
+	   i + lo < (u ? D_LOWLINE (u, FO) : hi + 1);
+	   i++)
+	{
+	  D_RELNUM (result, FILE0 + d, i) = D_RELNUM (result, FILEC, i);
+	  D_RELLEN (result, FILE0 + d, i) = D_RELLEN (result, FILEC, i);
+	}
+
+      for (ptr = u; ptr; ptr = D_NEXT (ptr))
+	{
+	  lin result_offset = D_LOWLINE (ptr, FO) - lo;
+	  lin linec;
+
+	  if (!copy_stringlist (D_LINEARRAY (ptr, FO),
+				D_LENARRAY (ptr, FO),
+				D_LINEARRAY (result, FILE0 + d) + result_offset,
+				D_LENARRAY (result, FILE0 + d) + result_offset,
+				D_NUMLINES (ptr, FO)))
+	    return 0;
+
+	  /* Catch the lines between here and the next diff */
+	  linec = D_HIGHLINE (ptr, FC) + 1 - lowc;
+	  for (i = D_HIGHLINE (ptr, FO) + 1 - lo;
+	       i < (D_NEXT (ptr) ? D_LOWLINE (D_NEXT (ptr), FO) : hi + 1) - lo;
+	       i++)
+	    {
+	      D_RELNUM (result, FILE0 + d, i) = D_RELNUM (result, FILEC, linec);
+	      D_RELLEN (result, FILE0 + d, i) = D_RELLEN (result, FILEC, linec);
+	      linec++;
+	    }
+	}
+    }
+
+  /* Set correspond */
+  if (!using[0])
+    D3_TYPE (result) = DIFF_2ND;
+  else if (!using[1])
+    D3_TYPE (result) = DIFF_1ST;
+  else
+    {
+      lin nl0 = D_NUMLINES (result, FILE0);
+      lin nl1 = D_NUMLINES (result, FILE1);
+
+      if (nl0 != nl1
+	  || !compare_line_list (D_LINEARRAY (result, FILE0),
+				 D_LENARRAY (result, FILE0),
+				 D_LINEARRAY (result, FILE1),
+				 D_LENARRAY (result, FILE1),
+				 nl0))
+	D3_TYPE (result) = DIFF_ALL;
+      else
+	D3_TYPE (result) = DIFF_3RD;
+    }
+
+  return result;
+}
+
+/* Copy pointers from a list of strings to a different list of
+   strings.  If a spot in the second list is already filled, make sure
+   that it is filled with the same string; if not, return false, the copy
+   incomplete.  Upon successful completion of the copy, return true.  */
+
+static bool
+copy_stringlist (char * const fromptrs[], size_t const fromlengths[],
+		 char *toptrs[], size_t tolengths[],
+		 lin copynum)
+{
+  register char * const *f = fromptrs;
+  register char **t = toptrs;
+  register size_t const *fl = fromlengths;
+  register size_t *tl = tolengths;
+
+  while (copynum--)
+    {
+      if (*t)
+	{
+	  if (*fl != *tl || memcmp (*f, *t, *fl) != 0)
+	    return false;
+	}
+      else
+	{
+	  *t = *f;
+	  *tl = *fl;
+	}
+
+      t++; f++; tl++; fl++;
+    }
+
+  return true;
+}
+
+/* Create a diff3_block, with ranges as specified in the arguments.
+   Allocate the arrays for the various pointers (and zero them) based
+   on the arguments passed.  Return the block as a result.  */
+
+static struct diff3_block *
+create_diff3_block (lin low0, lin high0,
+		    lin low1, lin high1,
+		    lin low2, lin high2)
+{
+  struct diff3_block *result = xmalloc (sizeof *result);
+  lin numlines;
+
+  D3_TYPE (result) = ERROR;
+  D_NEXT (result) = 0;
+
+  /* Assign ranges */
+  D_LOWLINE (result, FILE0) = low0;
+  D_HIGHLINE (result, FILE0) = high0;
+  D_LOWLINE (result, FILE1) = low1;
+  D_HIGHLINE (result, FILE1) = high1;
+  D_LOWLINE (result, FILE2) = low2;
+  D_HIGHLINE (result, FILE2) = high2;
+
+  /* Allocate and zero space */
+  numlines = D_NUMLINES (result, FILE0);
+  if (numlines)
+    {
+      D_LINEARRAY (result, FILE0) = xcalloc (numlines, sizeof (char *));
+      D_LENARRAY (result, FILE0) = xcalloc (numlines, sizeof (size_t));
+    }
+  else
+    {
+      D_LINEARRAY (result, FILE0) = 0;
+      D_LENARRAY (result, FILE0) = 0;
+    }
+
+  numlines = D_NUMLINES (result, FILE1);
+  if (numlines)
+    {
+      D_LINEARRAY (result, FILE1) = xcalloc (numlines, sizeof (char *));
+      D_LENARRAY (result, FILE1) = xcalloc (numlines, sizeof (size_t));
+    }
+  else
+    {
+      D_LINEARRAY (result, FILE1) = 0;
+      D_LENARRAY (result, FILE1) = 0;
+    }
+
+  numlines = D_NUMLINES (result, FILE2);
+  if (numlines)
+    {
+      D_LINEARRAY (result, FILE2) = xcalloc (numlines, sizeof (char *));
+      D_LENARRAY (result, FILE2) = xcalloc (numlines, sizeof (size_t));
+    }
+  else
+    {
+      D_LINEARRAY (result, FILE2) = 0;
+      D_LENARRAY (result, FILE2) = 0;
+    }
+
+  /* Return */
+  return result;
+}
+
+/* Compare two lists of lines of text.
+   Return 1 if they are equivalent, 0 if not.  */
+
+static bool
+compare_line_list (char * const list1[], size_t const lengths1[],
+		   char * const list2[], size_t const lengths2[],
+		   lin nl)
+{
+  char * const *l1 = list1;
+  char * const *l2 = list2;
+  size_t const *lgths1 = lengths1;
+  size_t const *lgths2 = lengths2;
+
+  while (nl--)
+    if (!*l1 || !*l2 || *lgths1 != *lgths2++
+	|| memcmp (*l1++, *l2++, *lgths1++) != 0)
+      return false;
+  return true;
+}
+
+/* Input and parse two way diffs.  */
+
+static struct diff_block *
+process_diff (char const *filea,
+	      char const *fileb,
+	      struct diff_block **last_block)
+{
+  char *diff_contents;
+  char *diff_limit;
+  char *scan_diff;
+  enum diff_type dt;
+  lin i;
+  struct diff_block *block_list;
+  struct diff_block **block_list_end = &block_list;
+  struct diff_block *bptr IF_LINT (= NULL);
+  size_t too_many_lines = (PTRDIFF_MAX
+			   / MIN (sizeof *bptr->lines[1],
+				  sizeof *bptr->lengths[1]));
+
+  diff_limit = read_diff (filea, fileb, &diff_contents);
+  scan_diff = diff_contents;
+
+  while (scan_diff < diff_limit)
+    {
+      bptr = xmalloc (sizeof *bptr);
+      bptr->lines[0] = bptr->lines[1] = 0;
+      bptr->lengths[0] = bptr->lengths[1] = 0;
+
+      dt = process_diff_control (&scan_diff, bptr);
+      if (dt == ERROR || *scan_diff != '\n')
+	{
+	  fprintf (stderr, _("%s: diff failed: "), program_name);
+	  do
+	    {
+	      putc (*scan_diff, stderr);
+	    }
+	  while (*scan_diff++ != '\n');
+	  exit (EXIT_TROUBLE);
+	}
+      scan_diff++;
+
+      /* Force appropriate ranges to be null, if necessary */
+      switch (dt)
+	{
+	case ADD:
+	  bptr->ranges[0][0]++;
+	  break;
+	case DELETE:
+	  bptr->ranges[1][0]++;
+	  break;
+	case CHANGE:
+	  break;
+	default:
+	  fatal ("internal error: invalid diff type in process_diff");
+	  break;
+	}
+
+      /* Allocate space for the pointers for the lines from filea, and
+	 parcel them out among these pointers */
+      if (dt != ADD)
+	{
+	  lin numlines = D_NUMLINES (bptr, 0);
+	  if (too_many_lines <= numlines)
+	    xalloc_die ();
+	  bptr->lines[0] = xmalloc (numlines * sizeof *bptr->lines[0]);
+	  bptr->lengths[0] = xmalloc (numlines * sizeof *bptr->lengths[0]);
+	  for (i = 0; i < numlines; i++)
+	    scan_diff = scan_diff_line (scan_diff,
+					&(bptr->lines[0][i]),
+					&(bptr->lengths[0][i]),
+					diff_limit,
+					'<');
+	}
+
+      /* Get past the separator for changes */
+      if (dt == CHANGE)
+	{
+	  if (strncmp (scan_diff, "---\n", 4))
+	    fatal ("invalid diff format; invalid change separator");
+	  scan_diff += 4;
+	}
+
+      /* Allocate space for the pointers for the lines from fileb, and
+	 parcel them out among these pointers */
+      if (dt != DELETE)
+	{
+	  lin numlines = D_NUMLINES (bptr, 1);
+	  if (too_many_lines <= numlines)
+	    xalloc_die ();
+	  bptr->lines[1] = xmalloc (numlines * sizeof *bptr->lines[1]);
+	  bptr->lengths[1] = xmalloc (numlines * sizeof *bptr->lengths[1]);
+	  for (i = 0; i < numlines; i++)
+	    scan_diff = scan_diff_line (scan_diff,
+					&(bptr->lines[1][i]),
+					&(bptr->lengths[1][i]),
+					diff_limit,
+					'>');
+	}
+
+      /* Place this block on the blocklist.  */
+      *block_list_end = bptr;
+      block_list_end = &bptr->next;
+    }
+
+  *block_list_end = NULL;
+  *last_block = bptr;
+  return block_list;
+}
+
+/* Skip tabs and spaces, and return the first character after them.  */
+
+static char *
+skipwhite (char *s)
+{
+  while (*s == ' ' || *s == '\t')
+    s++;
+  return s;
+}
+
+/* Read a nonnegative line number from S, returning the address of the
+   first character after the line number, and storing the number into
+   *PNUM.  Return 0 if S does not point to a valid line number.  */
+
+static char *
+readnum (char *s, lin *pnum)
+{
+  unsigned char c = *s;
+  lin num = 0;
+
+  if (! ISDIGIT (c))
+    return 0;
+
+  do
+    {
+      num = c - '0' + num * 10;
+      c = *++s;
+    }
+  while (ISDIGIT (c));
+
+  *pnum = num;
+  return s;
+}
+
+/* Parse a normal format diff control string.  Return the type of the
+   diff (ERROR if the format is bad).  All of the other important
+   information is filled into to the structure pointed to by db, and
+   the string pointer (whose location is passed to this routine) is
+   updated to point beyond the end of the string parsed.  Note that
+   only the ranges in the diff_block will be set by this routine.
+
+   If some specific pair of numbers has been reduced to a single
+   number, then both corresponding numbers in the diff block are set
+   to that number.  In general these numbers are interpreted as ranges
+   inclusive, unless being used by the ADD or DELETE commands.  It is
+   assumed that these will be special cased in a superior routine.   */
+
+static enum diff_type
+process_diff_control (char **string, struct diff_block *db)
+{
+  char *s = *string;
+  enum diff_type type;
+
+  /* Read first set of digits */
+  s = readnum (skipwhite (s), &db->ranges[0][RANGE_START]);
+  if (! s)
+    return ERROR;
+
+  /* Was that the only digit? */
+  s = skipwhite (s);
+  if (*s == ',')
+    {
+      s = readnum (s + 1, &db->ranges[0][RANGE_END]);
+      if (! s)
+	return ERROR;
+    }
+  else
+    db->ranges[0][RANGE_END] = db->ranges[0][RANGE_START];
+
+  /* Get the letter */
+  s = skipwhite (s);
+  switch (*s)
+    {
+    case 'a':
+      type = ADD;
+      break;
+    case 'c':
+      type = CHANGE;
+      break;
+    case 'd':
+      type = DELETE;
+      break;
+    default:
+      return ERROR;			/* Bad format */
+    }
+  s++;				/* Past letter */
+
+  /* Read second set of digits */
+  s = readnum (skipwhite (s), &db->ranges[1][RANGE_START]);
+  if (! s)
+    return ERROR;
+
+  /* Was that the only digit? */
+  s = skipwhite (s);
+  if (*s == ',')
+    {
+      s = readnum (s + 1, &db->ranges[1][RANGE_END]);
+      if (! s)
+	return ERROR;
+      s = skipwhite (s);		/* To move to end */
+    }
+  else
+    db->ranges[1][RANGE_END] = db->ranges[1][RANGE_START];
+
+  *string = s;
+  return type;
+}
+
+static char *
+read_diff (char const *filea,
+	   char const *fileb,
+	   char **output_placement)
+{
+  char *diff_result;
+  size_t current_chunk_size, total;
+  int fd, wstatus, status;
+  int werrno = 0;
+  struct stat pipestat;
+
+#if HAVE_WORKING_FORK
+
+  char const *argv[9];
+  char const **ap;
+  int fds[2];
+  pid_t pid;
+
+  ap = argv;
+  *ap++ = diff_program;
+  if (text)
+    *ap++ = "-a";
+  if (strip_trailing_cr)
+    *ap++ = "--strip-trailing-cr";
+  *ap++ = "--horizon-lines=100";
+  *ap++ = "--";
+  *ap++ = filea;
+  *ap++ = fileb;
+  *ap = 0;
+
+  if (pipe (fds) != 0)
+    perror_with_exit ("pipe");
+
+  pid = fork ();
+  if (pid == 0)
+    {
+      /* Child */
+      close (fds[0]);
+      if (fds[1] != STDOUT_FILENO)
+	{
+	  dup2 (fds[1], STDOUT_FILENO);
+	  close (fds[1]);
+	}
+
+      /* The cast to (char **) is needed for portability to older
+	 hosts with a nonstandard prototype for execvp.  */
+      execvp (diff_program, (char **) argv);
+
+      _exit (errno == ENOENT ? 127 : 126);
+    }
+
+  if (pid == -1)
+    perror_with_exit ("fork");
+
+  close (fds[1]);		/* Prevent erroneous lack of EOF */
+  fd = fds[0];
+
+#else
+
+  FILE *fpipe;
+  char const args[] = " --horizon-lines=100 -- ";
+  char *command = xmalloc (shell_quote_length (diff_program)
+			   + sizeof "-a"
+			   + sizeof "--strip-trailing-cr"
+			   + sizeof args - 1
+			   + shell_quote_length (filea) + 1
+			   + shell_quote_length (fileb) + 1);
+  char *p = command;
+  p = shell_quote_copy (p, diff_program);
+  if (text)
+    {
+      strcpy (p, " -a");
+      p += 3;
+    }
+  if (strip_trailing_cr)
+    {
+      strcpy (p, " --strip-trailing-cr");
+      p += 20;
+    }
+  strcpy (p, args);
+  p += sizeof args - 1;
+  p = shell_quote_copy (p, filea);
+  *p++ = ' ';
+  p = shell_quote_copy (p, fileb);
+  *p = 0;
+  errno = 0;
+  fpipe = popen (command, "r");
+  if (!fpipe)
+    perror_with_exit (command);
+  free (command);
+  fd = fileno (fpipe);
+
+#endif
+
+  if (fstat (fd, &pipestat) != 0)
+    perror_with_exit ("fstat");
+  current_chunk_size = MAX (1, STAT_BLOCKSIZE (pipestat));
+  diff_result = xmalloc (current_chunk_size);
+  total = 0;
+
+  for (;;)
+    {
+      size_t bytes_to_read = current_chunk_size - total;
+      size_t bytes = block_read (fd, diff_result + total, bytes_to_read);
+      total += bytes;
+      if (bytes != bytes_to_read)
+	{
+	  if (bytes == SIZE_MAX)
+	    perror_with_exit (_("read failed"));
+	  break;
+	}
+      if (PTRDIFF_MAX / 2 <= current_chunk_size)
+	xalloc_die ();
+      current_chunk_size *= 2;
+      diff_result = xrealloc (diff_result, current_chunk_size);
+    }
+
+  if (total != 0 && diff_result[total-1] != '\n')
+    fatal ("invalid diff format; incomplete last line");
+
+  *output_placement = diff_result;
+
+#if ! HAVE_WORKING_FORK
+
+  wstatus = pclose (fpipe);
+  if (wstatus == -1)
+    werrno = errno;
+
+#else
+
+  if (close (fd) != 0)
+    perror_with_exit ("close");
+  if (waitpid (pid, &wstatus, 0) < 0)
+    perror_with_exit ("waitpid");
+
+#endif
+
+  status = ! werrno && WIFEXITED (wstatus) ? WEXITSTATUS (wstatus) : INT_MAX;
+
+  if (EXIT_TROUBLE <= status)
+    error (EXIT_TROUBLE, werrno,
+	   _(status == 126
+	     ? "subsidiary program `%s' could not be invoked"
+	     : status == 127
+	     ? "subsidiary program `%s' not found"
+	     : status == INT_MAX
+	     ? "subsidiary program `%s' failed"
+	     : "subsidiary program `%s' failed (exit status %d)"),
+	   diff_program, status);
+
+  return diff_result + total;
+}
+
+
+/* Scan a regular diff line (consisting of > or <, followed by a
+   space, followed by text (including nulls) up to a newline.
+
+   This next routine began life as a macro and many parameters in it
+   are used as call-by-reference values.  */
+static char *
+scan_diff_line (char *scan_ptr, char **set_start, size_t *set_length,
+		char *limit, char leadingchar)
+{
+  char *line_ptr;
+
+  if (!(scan_ptr[0] == leadingchar
+	&& scan_ptr[1] == ' '))
+    fatal ("invalid diff format; incorrect leading line chars");
+
+  *set_start = line_ptr = scan_ptr + 2;
+  while (*line_ptr++ != '\n')
+    continue;
+
+  /* Include newline if the original line ended in a newline,
+     or if an edit script is being generated.
+     Copy any missing newline message to stderr if an edit script is being
+     generated, because edit scripts cannot handle missing newlines.
+     Return the beginning of the next line.  */
+  *set_length = line_ptr - *set_start;
+  if (line_ptr < limit && *line_ptr == '\\')
+    {
+      if (edscript)
+	fprintf (stderr, "%s:", program_name);
+      else
+	--*set_length;
+      line_ptr++;
+      do
+	{
+	  if (edscript)
+	    putc (*line_ptr, stderr);
+	}
+      while (*line_ptr++ != '\n');
+    }
+
+  return line_ptr;
+}
+
+/* Output a three way diff passed as a list of diff3_block's.  The
+   argument MAPPING is indexed by external file number (in the
+   argument list) and contains the internal file number (from the diff
+   passed).  This is important because the user expects outputs in
+   terms of the argument list number, and the diff passed may have
+   been done slightly differently (if the last argument was "-", for
+   example).  REV_MAPPING is the inverse of MAPPING.  */
+
+static void
+output_diff3 (FILE *outputfile, struct diff3_block *diff,
+	      int const mapping[3], int const rev_mapping[3])
+{
+  int i;
+  int oddoneout;
+  char *cp;
+  struct diff3_block *ptr;
+  lin line;
+  size_t length;
+  int dontprint;
+  static int skew_increment[3] = { 2, 3, 1 }; /* 0==>2==>1==>3 */
+  char const *line_prefix = initial_tab ? "\t" : "  ";
+
+  for (ptr = diff; ptr; ptr = D_NEXT (ptr))
+    {
+      char x[2];
+
+      switch (ptr->correspond)
+	{
+	case DIFF_ALL:
+	  x[0] = 0;
+	  dontprint = 3;	/* Print them all */
+	  oddoneout = 3;	/* Nobody's odder than anyone else */
+	  break;
+	case DIFF_1ST:
+	case DIFF_2ND:
+	case DIFF_3RD:
+	  oddoneout = rev_mapping[ptr->correspond - DIFF_1ST];
+
+	  x[0] = oddoneout + '1';
+	  x[1] = 0;
+	  dontprint = oddoneout == 0;
+	  break;
+	default:
+	  fatal ("internal error: invalid diff type passed to output");
+	}
+      fprintf (outputfile, "====%s\n", x);
+
+      /* Go 0, 2, 1 if the first and third outputs are equivalent.  */
+      for (i = 0; i < 3;
+	   i = (oddoneout == 1 ? skew_increment[i] : i + 1))
+	{
+	  int realfile = mapping[i];
+	  lin lowt = D_LOWLINE (ptr, realfile);
+	  lin hight = D_HIGHLINE (ptr, realfile);
+	  long int llowt = lowt;
+	  long int lhight = hight;
+
+	  fprintf (outputfile, "%d:", i + 1);
+	  switch (lowt - hight)
+	    {
+	    case 1:
+	      fprintf (outputfile, "%lda\n", llowt - 1);
+	      break;
+	    case 0:
+	      fprintf (outputfile, "%ldc\n", llowt);
+	      break;
+	    default:
+	      fprintf (outputfile, "%ld,%ldc\n", llowt, lhight);
+	      break;
+	    }
+
+	  if (i == dontprint) continue;
+
+	  if (lowt <= hight)
+	    {
+	      line = 0;
+	      do
+		{
+		  fputs (line_prefix, outputfile);
+		  cp = D_RELNUM (ptr, realfile, line);
+		  length = D_RELLEN (ptr, realfile, line);
+		  fwrite (cp, sizeof (char), length, outputfile);
+		}
+	      while (++line < hight - lowt + 1);
+	      if (cp[length - 1] != '\n')
+		fprintf (outputfile, "\n\\ %s\n",
+			 _("No newline at end of file"));
+	    }
+	}
+    }
+}
+
+
+/* Output to OUTPUTFILE the lines of B taken from FILENUM.  Double any
+   initial '.'s; yield nonzero if any initial '.'s were doubled.  */
+
+static bool
+dotlines (FILE *outputfile, struct diff3_block *b, int filenum)
+{
+  lin i;
+  bool leading_dot = false;
+
+  for (i = 0;
+       i < D_NUMLINES (b, filenum);
+       i++)
+    {
+      char *line = D_RELNUM (b, filenum, i);
+      if (line[0] == '.')
+	{
+	  leading_dot = true;
+	  fputc ('.', outputfile);
+	}
+      fwrite (line, sizeof (char),
+	      D_RELLEN (b, filenum, i), outputfile);
+    }
+
+  return leading_dot;
+}
+
+/* Output to OUTPUTFILE a '.' line.  If LEADING_DOT is true, also
+   output a command that removes initial '.'s starting with line START
+   and continuing for NUM lines.  (START is long int, not lin, for
+   convenience with printf %ld formats.)  */
+
+static void
+undotlines (FILE *outputfile, bool leading_dot, long int start, lin num)
+{
+  fputs (".\n", outputfile);
+  if (leading_dot)
+    {
+      if (num == 1)
+	fprintf (outputfile, "%lds/^\\.//\n", start);
+      else
+	fprintf (outputfile, "%ld,%lds/^\\.//\n", start, start + num - 1);
+    }
+}
+
+/* Output a diff3 set of blocks as an ed script.  This script applies
+   the changes between file's 2 & 3 to file 1.  Take the precise
+   format of the ed script to be output from global variables set
+   during options processing.  Reverse the order of
+   the set of diff3 blocks in DIFF; this gets
+   around the problems involved with changing line numbers in an ed
+   script.
+
+   As in `output_diff3', the variable MAPPING maps from file number
+   according to the argument list to file number according to the diff
+   passed.  All files listed below are in terms of the argument list.
+   REV_MAPPING is the inverse of MAPPING.
+
+   FILE0, FILE1 and FILE2 are the strings to print as the names of the
+   three files.  These may be the actual names, or may be the
+   arguments specified with -L.
+
+   Return 1 if conflicts were found.  */
+
+static bool
+output_diff3_edscript (FILE *outputfile, struct diff3_block *diff,
+		       int const mapping[3], int const rev_mapping[3],
+		       char const *file0, char const *file1, char const *file2)
+{
+  bool leading_dot;
+  bool conflicts_found = false;
+  bool conflict;
+  struct diff3_block *b;
+
+  for (b = reverse_diff3_blocklist (diff); b; b = b->next)
+    {
+      /* Must do mapping correctly.  */
+      enum diff_type type
+	= (b->correspond == DIFF_ALL
+	   ? DIFF_ALL
+	   : DIFF_1ST + rev_mapping[b->correspond - DIFF_1ST]);
+
+      long int low0, high0;
+
+      /* If we aren't supposed to do this output block, skip it.  */
+      switch (type)
+	{
+	default: continue;
+	case DIFF_2ND: if (!show_2nd) continue; conflict = true; break;
+	case DIFF_3RD: if (overlap_only) continue; conflict = false; break;
+	case DIFF_ALL: if (simple_only) continue; conflict = flagging; break;
+	}
+
+      low0 = D_LOWLINE (b, mapping[FILE0]);
+      high0 = D_HIGHLINE (b, mapping[FILE0]);
+
+      if (conflict)
+	{
+	  conflicts_found = true;
+
+
+	  /* Mark end of conflict.  */
+
+	  fprintf (outputfile, "%lda\n", high0);
+	  leading_dot = false;
+	  if (type == DIFF_ALL)
+	    {
+	      if (show_2nd)
+		{
+		  /* Append lines from FILE1.  */
+		  fprintf (outputfile, "||||||| %s\n", file1);
+		  leading_dot = dotlines (outputfile, b, mapping[FILE1]);
+		}
+	      /* Append lines from FILE2.  */
+	      fputs ("=======\n", outputfile);
+	      leading_dot |= dotlines (outputfile, b, mapping[FILE2]);
+	    }
+	  fprintf (outputfile, ">>>>>>> %s\n", file2);
+	  undotlines (outputfile, leading_dot, high0 + 2,
+		      (D_NUMLINES (b, mapping[FILE1])
+		       + D_NUMLINES (b, mapping[FILE2]) + 1));
+
+
+	  /* Mark start of conflict.  */
+
+	  fprintf (outputfile, "%lda\n<<<<<<< %s\n", low0 - 1,
+		   type == DIFF_ALL ? file0 : file1);
+	  leading_dot = false;
+	  if (type == DIFF_2ND)
+	    {
+	      /* Prepend lines from FILE1.  */
+	      leading_dot = dotlines (outputfile, b, mapping[FILE1]);
+	      fputs ("=======\n", outputfile);
+	    }
+	  undotlines (outputfile, leading_dot, low0 + 1,
+		      D_NUMLINES (b, mapping[FILE1]));
+	}
+      else if (D_NUMLINES (b, mapping[FILE2]) == 0)
+	/* Write out a delete */
+	{
+	  if (low0 == high0)
+	    fprintf (outputfile, "%ldd\n", low0);
+	  else
+	    fprintf (outputfile, "%ld,%ldd\n", low0, high0);
+	}
+      else
+	/* Write out an add or change */
+	{
+	  switch (high0 - low0)
+	    {
+	    case -1:
+	      fprintf (outputfile, "%lda\n", high0);
+	      break;
+	    case 0:
+	      fprintf (outputfile, "%ldc\n", high0);
+	      break;
+	    default:
+	      fprintf (outputfile, "%ld,%ldc\n", low0, high0);
+	      break;
+	    }
+
+	  undotlines (outputfile, dotlines (outputfile, b, mapping[FILE2]),
+		      low0, D_NUMLINES (b, mapping[FILE2]));
+	}
+    }
+  if (finalwrite)
+    fputs ("w\nq\n", outputfile);
+  return conflicts_found;
+}
+
+/* Read from INFILE and output to OUTPUTFILE a set of diff3_blocks
+   DIFF as a merged file.  This acts like 'ed file0
+   <[output_diff3_edscript]', except that it works even for binary
+   data or incomplete lines.
+
+   As before, MAPPING maps from arg list file number to diff file
+   number, REV_MAPPING is its inverse, and FILE0, FILE1, and FILE2 are
+   the names of the files.
+
+   Return 1 if conflicts were found.  */
+
+static bool
+output_diff3_merge (FILE *infile, FILE *outputfile, struct diff3_block *diff,
+		    int const mapping[3], int const rev_mapping[3],
+		    char const *file0, char const *file1, char const *file2)
+{
+  int c;
+  lin i;
+  bool conflicts_found = false;
+  bool conflict;
+  struct diff3_block *b;
+  lin linesread = 0;
+
+  for (b = diff; b; b = b->next)
+    {
+      /* Must do mapping correctly.  */
+      enum diff_type type
+	= ((b->correspond == DIFF_ALL)
+	   ? DIFF_ALL
+	   : DIFF_1ST + rev_mapping[b->correspond - DIFF_1ST]);
+      char const *format_2nd = "<<<<<<< %s\n";
+
+      /* If we aren't supposed to do this output block, skip it.  */
+      switch (type)
+	{
+	default: continue;
+	case DIFF_2ND: if (!show_2nd) continue; conflict = true; break;
+	case DIFF_3RD: if (overlap_only) continue; conflict = false; break;
+	case DIFF_ALL: if (simple_only) continue; conflict = flagging;
+	  format_2nd = "||||||| %s\n";
+	  break;
+	}
+
+      /* Copy I lines from file 0.  */
+      i = D_LOWLINE (b, FILE0) - linesread - 1;
+      linesread += i;
+      while (0 <= --i)
+	do
+	  {
+	    c = getc (infile);
+	    if (c == EOF)
+	      {
+		if (ferror (infile))
+		  perror_with_exit (_("read failed"));
+		else if (feof (infile))
+		  fatal ("input file shrank");
+	      }
+	    putc (c, outputfile);
+	  }
+	while (c != '\n');
+
+      if (conflict)
+	{
+	  conflicts_found = true;
+
+	  if (type == DIFF_ALL)
+	    {
+	      /* Put in lines from FILE0 with bracket.  */
+	      fprintf (outputfile, "<<<<<<< %s\n", file0);
+	      for (i = 0;
+		   i < D_NUMLINES (b, mapping[FILE0]);
+		   i++)
+		fwrite (D_RELNUM (b, mapping[FILE0], i), sizeof (char),
+			D_RELLEN (b, mapping[FILE0], i), outputfile);
+	    }
+
+	  if (show_2nd)
+	    {
+	      /* Put in lines from FILE1 with bracket.  */
+	      fprintf (outputfile, format_2nd, file1);
+	      for (i = 0;
+		   i < D_NUMLINES (b, mapping[FILE1]);
+		   i++)
+		fwrite (D_RELNUM (b, mapping[FILE1], i), sizeof (char),
+			D_RELLEN (b, mapping[FILE1], i), outputfile);
+	    }
+
+	  fputs ("=======\n", outputfile);
+	}
+
+      /* Put in lines from FILE2.  */
+      for (i = 0;
+	   i < D_NUMLINES (b, mapping[FILE2]);
+	   i++)
+	fwrite (D_RELNUM (b, mapping[FILE2], i), sizeof (char),
+		D_RELLEN (b, mapping[FILE2], i), outputfile);
+
+      if (conflict)
+	fprintf (outputfile, ">>>>>>> %s\n", file2);
+
+      /* Skip I lines in file 0.  */
+      i = D_NUMLINES (b, FILE0);
+      linesread += i;
+      while (0 <= --i)
+	while ((c = getc (infile)) != '\n')
+	  if (c == EOF)
+	    {
+	      if (ferror (infile))
+		perror_with_exit (_("read failed"));
+	      else if (feof (infile))
+		{
+		  if (i || b->next)
+		    fatal ("input file shrank");
+		  return conflicts_found;
+		}
+	    }
+    }
+  /* Copy rest of common file.  */
+  while ((c = getc (infile)) != EOF || !(ferror (infile) | feof (infile)))
+    putc (c, outputfile);
+  return conflicts_found;
+}
+
+/* Reverse the order of the list of diff3 blocks.  */
+
+static struct diff3_block *
+reverse_diff3_blocklist (struct diff3_block *diff)
+{
+  register struct diff3_block *tmp, *next, *prev;
+
+  for (tmp = diff, prev = 0;  tmp;  tmp = next)
+    {
+      next = tmp->next;
+      tmp->next = prev;
+      prev = tmp;
+    }
+
+  return prev;
+}
+
+static void
+fatal (char const *msgid)
+{
+  error (EXIT_TROUBLE, 0, "%s", _(msgid));
+  abort ();
+}
+
+static void
+perror_with_exit (char const *string)
+{
+  error (EXIT_TROUBLE, errno, "%s", string);
+  abort ();
+}
diff --git a/src/dir.c b/src/dir.c
new file mode 100644
index 0000000..20626d1
--- /dev/null
+++ b/src/dir.c
@@ -0,0 +1,364 @@
+/* Read, sort and compare two directories.  Used for GNU DIFF.
+
+   Copyright (C) 1988-1989, 1992-1995, 1998, 2001-2002, 2004, 2006-2007,
+   2009-2011 Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "diff.h"
+#include <error.h>
+#include <exclude.h>
+#include <filenamecat.h>
+#include <setjmp.h>
+#include <xalloc.h>
+
+/* Read the directory named by DIR and store into DIRDATA a sorted vector
+   of filenames for its contents.  DIR->desc == -1 means this directory is
+   known to be nonexistent, so set DIRDATA to an empty vector.
+   Return -1 (setting errno) if error, 0 otherwise.  */
+
+struct dirdata
+{
+  size_t nnames;	/* Number of names.  */
+  char const **names;	/* Sorted names of files in dir, followed by 0.  */
+  char *data;	/* Allocated storage for file names.  */
+};
+
+/* Whether file names in directories should be compared with
+   locale-specific sorting.  */
+static bool locale_specific_sorting;
+
+/* Where to go if locale-specific sorting fails.  */
+static jmp_buf failed_locale_specific_sorting;
+
+static bool dir_loop (struct comparison const *, int);
+static int compare_names_for_qsort (void const *, void const *);
+
+
+/* Read a directory and get its vector of names.  */
+
+static bool
+dir_read (struct file_data const *dir, struct dirdata *dirdata)
+{
+  register struct dirent *next;
+  register size_t i;
+
+  /* Address of block containing the files that are described.  */
+  char const **names;
+
+  /* Number of files in directory.  */
+  size_t nnames;
+
+  /* Allocated and used storage for file name data.  */
+  char *data;
+  size_t data_alloc, data_used;
+
+  dirdata->names = 0;
+  dirdata->data = 0;
+  nnames = 0;
+  data = 0;
+
+  if (dir->desc != -1)
+    {
+      /* Open the directory and check for errors.  */
+      register DIR *reading = opendir (dir->name);
+      if (!reading)
+	return false;
+
+      /* Initialize the table of filenames.  */
+
+      data_alloc = 512;
+      data_used = 0;
+      dirdata->data = data = xmalloc (data_alloc);
+
+      /* Read the directory entries, and insert the subfiles
+	 into the `data' table.  */
+
+      while ((errno = 0, (next = readdir (reading)) != 0))
+	{
+	  char *d_name = next->d_name;
+	  size_t d_size = _D_EXACT_NAMLEN (next) + 1;
+
+	  /* Ignore "." and "..".  */
+	  if (d_name[0] == '.'
+	      && (d_name[1] == 0 || (d_name[1] == '.' && d_name[2] == 0)))
+	    continue;
+
+	  if (excluded_file_name (excluded, d_name))
+	    continue;
+
+	  while (data_alloc < data_used + d_size)
+	    {
+	      if (PTRDIFF_MAX / 2 <= data_alloc)
+		xalloc_die ();
+	      dirdata->data = data = xrealloc (data, data_alloc *= 2);
+	    }
+
+	  memcpy (data + data_used, d_name, d_size);
+	  data_used += d_size;
+	  nnames++;
+	}
+      if (errno)
+	{
+	  int e = errno;
+	  closedir (reading);
+	  errno = e;
+	  return false;
+	}
+#if CLOSEDIR_VOID
+      closedir (reading);
+#else
+      if (closedir (reading) != 0)
+	return false;
+#endif
+    }
+
+  /* Create the `names' table from the `data' table.  */
+  if (PTRDIFF_MAX / sizeof *names - 1 <= nnames)
+    xalloc_die ();
+  dirdata->names = names = xmalloc ((nnames + 1) * sizeof *names);
+  dirdata->nnames = nnames;
+  for (i = 0;  i < nnames;  i++)
+    {
+      names[i] = data;
+      data += strlen (data) + 1;
+    }
+  names[nnames] = 0;
+  return true;
+}
+
+/* Compare file names, returning a value compatible with strcmp.  */
+
+static int
+compare_names (char const *name1, char const *name2)
+{
+  if (locale_specific_sorting)
+    {
+      int r;
+      errno = 0;
+      if (ignore_file_name_case)
+	r = strcasecoll (name1, name2);
+      else
+	r = strcoll (name1, name2);
+      if (errno)
+	{
+	  error (0, errno, _("cannot compare file names `%s' and `%s'"),
+		 name1, name2);
+	  longjmp (failed_locale_specific_sorting, 1);
+	}
+      return r;
+    }
+
+  return file_name_cmp (name1, name2);
+}
+
+/* Compare names FILE1 and FILE2 when sorting a directory.
+   Prefer filtered comparison, breaking ties with file_name_cmp.  */
+
+static int
+compare_names_for_qsort (void const *file1, void const *file2)
+{
+  char const *const *f1 = file1;
+  char const *const *f2 = file2;
+  int diff = compare_names (*f1, *f2);
+  return diff ? diff : file_name_cmp (*f1, *f2);
+}
+
+/* Compare the contents of two directories named in CMP.
+   This is a top-level routine; it does everything necessary for diff
+   on two directories.
+
+   CMP->file[0].desc == -1 says directory CMP->file[0] doesn't exist,
+   but pretend it is empty.  Likewise for CMP->file[1].
+
+   HANDLE_FILE is a caller-provided subroutine called to handle each file.
+   It gets three operands: CMP, name of file in dir 0, name of file in dir 1.
+   These names are relative to the original working directory.
+
+   For a file that appears in only one of the dirs, one of the name-args
+   to HANDLE_FILE is zero.
+
+   Returns the maximum of all the values returned by HANDLE_FILE,
+   or EXIT_TROUBLE if trouble is encountered in opening files.  */
+
+int
+diff_dirs (struct comparison const *cmp,
+	   int (*handle_file) (struct comparison const *,
+			       char const *, char const *))
+{
+  struct dirdata dirdata[2];
+  int volatile val = EXIT_SUCCESS;
+  int i;
+
+  if ((cmp->file[0].desc == -1 || dir_loop (cmp, 0))
+      && (cmp->file[1].desc == -1 || dir_loop (cmp, 1)))
+    {
+      error (0, 0, _("%s: recursive directory loop"),
+	     cmp->file[cmp->file[0].desc == -1].name);
+      return EXIT_TROUBLE;
+    }
+
+  /* Get contents of both dirs.  */
+  for (i = 0; i < 2; i++)
+    if (! dir_read (&cmp->file[i], &dirdata[i]))
+      {
+	perror_with_name (cmp->file[i].name);
+	val = EXIT_TROUBLE;
+      }
+
+  if (val == EXIT_SUCCESS)
+    {
+      char const **volatile names[2];
+      names[0] = dirdata[0].names;
+      names[1] = dirdata[1].names;
+
+      /* Use locale-specific sorting if possible, else native byte order.  */
+      locale_specific_sorting = true;
+      if (setjmp (failed_locale_specific_sorting))
+	locale_specific_sorting = false;
+
+      /* Sort the directories.  */
+      for (i = 0; i < 2; i++)
+	qsort (names[i], dirdata[i].nnames, sizeof *dirdata[i].names,
+	       compare_names_for_qsort);
+
+      /* If `-S name' was given, and this is the topmost level of comparison,
+	 ignore all file names less than the specified starting name.  */
+
+      if (starting_file && ! cmp->parent)
+	{
+	  while (*names[0] && compare_names (*names[0], starting_file) < 0)
+	    names[0]++;
+	  while (*names[1] && compare_names (*names[1], starting_file) < 0)
+	    names[1]++;
+	}
+
+      /* Loop while files remain in one or both dirs.  */
+      while (*names[0] || *names[1])
+	{
+	  /* Compare next name in dir 0 with next name in dir 1.
+	     At the end of a dir,
+	     pretend the "next name" in that dir is very large.  */
+	  int nameorder = (!*names[0] ? 1 : !*names[1] ? -1
+			   : compare_names (*names[0], *names[1]));
+
+	  /* Prefer a file_name_cmp match if available.  This algorithm is
+	     O(N**2), where N is the number of names in a directory
+	     that compare_names says are all equal, but in practice N
+	     is so small it's not worth tuning.  */
+	  if (nameorder == 0)
+	    {
+	      int raw_order = file_name_cmp (*names[0], *names[1]);
+	      if (raw_order != 0)
+		{
+		  int greater_side = raw_order < 0;
+		  int lesser_side = 1 - greater_side;
+		  char const **lesser = names[lesser_side];
+		  char const *greater_name = *names[greater_side];
+		  char const **p;
+
+		  for (p = lesser + 1;
+		       *p && compare_names (*p, greater_name) == 0;
+		       p++)
+		    {
+		      int c = file_name_cmp (*p, greater_name);
+		      if (0 <= c)
+			{
+			  if (c == 0)
+			    {
+			      memmove (lesser + 1, lesser,
+				       (char *) p - (char *) lesser);
+			      *lesser = greater_name;
+			    }
+			  break;
+			}
+		    }
+		}
+	    }
+
+	  int v1 = (*handle_file) (cmp,
+				   0 < nameorder ? 0 : *names[0]++,
+				   nameorder < 0 ? 0 : *names[1]++);
+	  if (val < v1)
+	    val = v1;
+	}
+    }
+
+  for (i = 0; i < 2; i++)
+    {
+      free (dirdata[i].names);
+      free (dirdata[i].data);
+    }
+
+  return val;
+}
+
+/* Return nonzero if CMP is looping recursively in argument I.  */
+
+static bool
+dir_loop (struct comparison const *cmp, int i)
+{
+  struct comparison const *p = cmp;
+  while ((p = p->parent))
+    if (0 < same_file (&p->file[i].stat, &cmp->file[i].stat))
+      return true;
+  return false;
+}
+
+/* Find a matching filename in a directory.  */
+
+char *
+find_dir_file_pathname (char const *dir, char const *file)
+{
+  char *val;
+  char const *match = file;
+  struct dirdata dirdata;
+  dirdata.names = NULL;
+  dirdata.data = NULL;
+
+  if (ignore_file_name_case)
+    {
+      struct file_data filedata;
+      filedata.name = dir;
+      filedata.desc = 0;
+
+      if (dir_read (&filedata, &dirdata))
+	{
+	  locale_specific_sorting = true;
+	  if (setjmp (failed_locale_specific_sorting))
+	    match = file; /* longjmp may mess up MATCH.  */
+	  else
+	    {
+	      for (char const **p = dirdata.names; *p; p++)
+		if (compare_names (*p, file) == 0)
+		  {
+		    if (file_name_cmp (*p, file) == 0)
+		      {
+			match = *p;
+			break;
+		      }
+		    if (match == file)
+		      match = *p;
+		  }
+	    }
+	}
+    }
+
+  val = file_name_concat (dir, match, NULL);
+  free (dirdata.names);
+  free (dirdata.data);
+  return val;
+}
diff --git a/src/ed.c b/src/ed.c
new file mode 100644
index 0000000..88b617c
--- /dev/null
+++ b/src/ed.c
@@ -0,0 +1,175 @@
+/* Output routines for ed-script format.
+
+   Copyright (C) 1988-1989, 1991-1993, 1995, 1998, 2001, 2004, 2006, 2009-2011
+   Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "diff.h"
+
+static void print_ed_hunk (struct change *);
+static void print_rcs_hunk (struct change *);
+static void pr_forward_ed_hunk (struct change *);
+
+/* Print our script as ed commands.  */
+
+void
+print_ed_script (struct change *script)
+{
+  print_script (script, find_reverse_change, print_ed_hunk);
+}
+
+/* Print a hunk of an ed diff */
+
+static void
+print_ed_hunk (struct change *hunk)
+{
+  lin f0, l0, f1, l1;
+  enum changes changes;
+
+#ifdef DEBUG
+  debug_script (hunk);
+#endif
+
+  /* Determine range of line numbers involved in each file.  */
+  changes = analyze_hunk (hunk, &f0, &l0, &f1, &l1);
+  if (!changes)
+    return;
+
+  begin_output ();
+
+  /* Print out the line number header for this hunk */
+  print_number_range (',', &files[0], f0, l0);
+  fputc (change_letter[changes], outfile);
+  fputc ('\n', outfile);
+
+  /* Print new/changed lines from second file, if needed */
+  if (changes != OLD)
+    {
+      lin i;
+      bool insert_mode = true;
+
+      for (i = f1; i <= l1; i++)
+	{
+	  if (!insert_mode)
+	    {
+	      fputs ("a\n", outfile);
+	      insert_mode = true;
+	    }
+	  if (files[1].linbuf[i][0] == '.' && files[1].linbuf[i][1] == '\n')
+	    {
+	      /* The file's line is just a dot, and it would exit
+		 insert mode.  Precede the dot with another dot, exit
+		 insert mode and remove the extra dot.  */
+	      fputs ("..\n.\ns/.//\n", outfile);
+	      insert_mode = false;
+	    }
+	  else
+	    print_1_line ("", &files[1].linbuf[i]);
+	}
+
+      if (insert_mode)
+	fputs (".\n", outfile);
+    }
+}
+
+/* Print change script in the style of ed commands,
+   but print the changes in the order they appear in the input files,
+   which means that the commands are not truly useful with ed.
+   Because of the issue with lines containing just a dot, the output
+   is not even parseable.  */
+
+void
+pr_forward_ed_script (struct change *script)
+{
+  print_script (script, find_change, pr_forward_ed_hunk);
+}
+
+static void
+pr_forward_ed_hunk (struct change *hunk)
+{
+  lin i, f0, l0, f1, l1;
+
+  /* Determine range of line numbers involved in each file.  */
+  enum changes changes = analyze_hunk (hunk, &f0, &l0, &f1, &l1);
+  if (!changes)
+    return;
+
+  begin_output ();
+
+  fputc (change_letter[changes], outfile);
+  print_number_range (' ', files, f0, l0);
+  fputc ('\n', outfile);
+
+  /* If deletion only, print just the number range.  */
+
+  if (changes == OLD)
+    return;
+
+  /* For insertion (with or without deletion), print the number range
+     and the lines from file 2.  */
+
+  for (i = f1; i <= l1; i++)
+    print_1_line ("", &files[1].linbuf[i]);
+
+  fputs (".\n", outfile);
+}
+
+/* Print in a format somewhat like ed commands
+   except that each insert command states the number of lines it inserts.
+   This format is used for RCS.  */
+
+void
+print_rcs_script (struct change *script)
+{
+  print_script (script, find_change, print_rcs_hunk);
+}
+
+/* Print a hunk of an RCS diff */
+
+static void
+print_rcs_hunk (struct change *hunk)
+{
+  lin i, f0, l0, f1, l1;
+  long int tf0, tl0, tf1, tl1;
+
+  /* Determine range of line numbers involved in each file.  */
+  enum changes changes = analyze_hunk (hunk, &f0, &l0, &f1, &l1);
+  if (!changes)
+    return;
+
+  begin_output ();
+
+  translate_range (&files[0], f0, l0, &tf0, &tl0);
+
+  if (changes & OLD)
+    {
+      /* For deletion, print just the starting line number from file 0
+	 and the number of lines deleted.  */
+      fprintf (outfile, "d%ld %ld\n", tf0, tf0 <= tl0 ? tl0 - tf0 + 1 : 1);
+    }
+
+  if (changes & NEW)
+    {
+      /* Take last-line-number from file 0 and # lines from file 1.  */
+      translate_range (&files[1], f1, l1, &tf1, &tl1);
+      fprintf (outfile, "a%ld %ld\n", tl0, tf1 <= tl1 ? tl1 - tf1 + 1 : 1);
+
+      /* Print the inserted lines.  */
+      for (i = f1; i <= l1; i++)
+	print_1_line ("", &files[1].linbuf[i]);
+    }
+}
diff --git a/src/ifdef.c b/src/ifdef.c
new file mode 100644
index 0000000..bc5c8c5
--- /dev/null
+++ b/src/ifdef.c
@@ -0,0 +1,430 @@
+/* #ifdef-format output routines for GNU DIFF.
+
+   Copyright (C) 1989, 1991-1994, 2001-2002, 2004, 2006, 2009-2011 Free
+   Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   GNU DIFF is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY.  No author or distributor
+   accepts responsibility to anyone for the consequences of using it
+   or for whether it serves any particular purpose or works at all,
+   unless he says so in writing.  Refer to the GNU General Public
+   License for full details.
+
+   Everyone is granted permission to copy, modify and redistribute
+   GNU DIFF, but only under the conditions described in the
+   GNU General Public License.   A copy of this license is
+   supposed to have been given to you along with GNU DIFF so you
+   can know your rights and responsibilities.  It should be in a
+   file named COPYING.  Among other things, the copyright notice
+   and this notice must be preserved on all copies.  */
+
+#include "diff.h"
+
+#include <xalloc.h>
+
+struct group
+{
+  struct file_data const *file;
+  lin from, upto; /* start and limit lines for this group of lines */
+};
+
+static char const *format_group (FILE *, char const *, char,
+				 struct group const *);
+static char const *do_printf_spec (FILE *, char const *,
+				   struct file_data const *, lin,
+				   struct group const *);
+static char const *scan_char_literal (char const *, char *);
+static lin groups_letter_value (struct group const *, char);
+static void format_ifdef (char const *, lin, lin, lin, lin);
+static void print_ifdef_hunk (struct change *);
+static void print_ifdef_lines (FILE *, char const *, struct group const *);
+
+static lin next_line0;
+static lin next_line1;
+
+/* Print the edit-script SCRIPT as a merged #ifdef file.  */
+
+void
+print_ifdef_script (struct change *script)
+{
+  next_line0 = next_line1 = - files[0].prefix_lines;
+  print_script (script, find_change, print_ifdef_hunk);
+  if (next_line0 < files[0].valid_lines
+      || next_line1 < files[1].valid_lines)
+    {
+      begin_output ();
+      format_ifdef (group_format[UNCHANGED],
+		    next_line0, files[0].valid_lines,
+		    next_line1, files[1].valid_lines);
+    }
+}
+
+/* Print a hunk of an ifdef diff.
+   This is a contiguous portion of a complete edit script,
+   describing changes in consecutive lines.  */
+
+static void
+print_ifdef_hunk (struct change *hunk)
+{
+  lin first0, last0, first1, last1;
+
+  /* Determine range of line numbers involved in each file.  */
+  enum changes changes = analyze_hunk (hunk, &first0, &last0, &first1, &last1);
+  if (!changes)
+    return;
+
+  begin_output ();
+
+  /* Print lines up to this change.  */
+  if (next_line0 < first0 || next_line1 < first1)
+    format_ifdef (group_format[UNCHANGED],
+		  next_line0, first0,
+		  next_line1, first1);
+
+  /* Print this change.  */
+  next_line0 = last0 + 1;
+  next_line1 = last1 + 1;
+  format_ifdef (group_format[changes],
+		first0, next_line0,
+		first1, next_line1);
+}
+
+/* Print a set of lines according to FORMAT.
+   Lines BEG0 up to END0 are from the first file;
+   lines BEG1 up to END1 are from the second file.  */
+
+static void
+format_ifdef (char const *format, lin beg0, lin end0, lin beg1, lin end1)
+{
+  struct group groups[2];
+
+  groups[0].file = &files[0];
+  groups[0].from = beg0;
+  groups[0].upto = end0;
+  groups[1].file = &files[1];
+  groups[1].from = beg1;
+  groups[1].upto = end1;
+  format_group (outfile, format, 0, groups);
+}
+
+/* Print to file OUT a set of lines according to FORMAT.
+   The format ends at the first free instance of ENDCHAR.
+   Yield the address of the terminating character.
+   GROUPS specifies which lines to print.
+   If OUT is zero, do not actually print anything; just scan the format.  */
+
+static char const *
+format_group (register FILE *out, char const *format, char endchar,
+	      struct group const *groups)
+{
+  register char c;
+  register char const *f = format;
+
+  while ((c = *f) != endchar && c != 0)
+    {
+      char const *f1 = ++f;
+      if (c == '%')
+	switch ((c = *f++))
+	  {
+	  case '%':
+	    break;
+
+	  case '(':
+	    /* Print if-then-else format e.g. `%(n=1?thenpart:elsepart)'.  */
+	    {
+	      int i;
+	      uintmax_t value[2];
+	      FILE *thenout, *elseout;
+
+	      for (i = 0; i < 2; i++)
+		{
+		  if (ISDIGIT (*f))
+		    {
+		      char *fend;
+		      errno = 0;
+		      value[i] = strtoumax (f, &fend, 10);
+		      if (errno)
+			goto bad_format;
+		      f = fend;
+		    }
+		  else
+		    {
+		      value[i] = groups_letter_value (groups, *f);
+		      if (value[i] == -1)
+			goto bad_format;
+		      f++;
+		    }
+		  if (*f++ != "=?"[i])
+		    goto bad_format;
+		}
+	      if (value[0] == value[1])
+		thenout = out, elseout = 0;
+	      else
+		thenout = 0, elseout = out;
+	      f = format_group (thenout, f, ':', groups);
+	      if (*f)
+		{
+		  f = format_group (elseout, f + 1, ')', groups);
+		  if (*f)
+		    f++;
+		}
+	    }
+	    continue;
+
+	  case '<':
+	    /* Print lines deleted from first file.  */
+	    print_ifdef_lines (out, line_format[OLD], &groups[0]);
+	    continue;
+
+	  case '=':
+	    /* Print common lines.  */
+	    print_ifdef_lines (out, line_format[UNCHANGED], &groups[0]);
+	    continue;
+
+	  case '>':
+	    /* Print lines inserted from second file.  */
+	    print_ifdef_lines (out, line_format[NEW], &groups[1]);
+	    continue;
+
+	  default:
+	    f = do_printf_spec (out, f - 2, 0, 0, groups);
+	    if (f)
+	      continue;
+	    /* Fall through. */
+	  bad_format:
+	    c = '%';
+	    f = f1;
+	    break;
+	  }
+
+      if (out)
+	putc (c, out);
+    }
+
+  return f;
+}
+
+/* For the line group pair G, return the number corresponding to LETTER.
+   Return -1 if LETTER is not a group format letter.  */
+static lin
+groups_letter_value (struct group const *g, char letter)
+{
+  switch (letter)
+    {
+    case 'E': letter = 'e'; g++; break;
+    case 'F': letter = 'f'; g++; break;
+    case 'L': letter = 'l'; g++; break;
+    case 'M': letter = 'm'; g++; break;
+    case 'N': letter = 'n'; g++; break;
+    }
+
+  switch (letter)
+    {
+      case 'e': return translate_line_number (g->file, g->from) - 1;
+      case 'f': return translate_line_number (g->file, g->from);
+      case 'l': return translate_line_number (g->file, g->upto) - 1;
+      case 'm': return translate_line_number (g->file, g->upto);
+      case 'n': return g->upto - g->from;
+      default: return -1;
+    }
+}
+
+/* Print to file OUT, using FORMAT to print the line group GROUP.
+   But do nothing if OUT is zero.  */
+static void
+print_ifdef_lines (register FILE *out, char const *format,
+		   struct group const *group)
+{
+  struct file_data const *file = group->file;
+  char const * const *linbuf = file->linbuf;
+  lin from = group->from, upto = group->upto;
+
+  if (!out)
+    return;
+
+  /* If possible, use a single fwrite; it's faster.  */
+  if (!expand_tabs && format[0] == '%')
+    {
+      if (format[1] == 'l' && format[2] == '\n' && !format[3] && from < upto)
+	{
+	  fwrite (linbuf[from], sizeof (char),
+		  linbuf[upto] + (linbuf[upto][-1] != '\n') -  linbuf[from],
+		  out);
+	  return;
+	}
+      if (format[1] == 'L' && !format[2])
+	{
+	  fwrite (linbuf[from], sizeof (char),
+		  linbuf[upto] -  linbuf[from], out);
+	  return;
+	}
+    }
+
+  for (;  from < upto;  from++)
+    {
+      register char c;
+      register char const *f = format;
+
+      while ((c = *f++) != 0)
+	{
+	  char const *f1 = f;
+	  if (c == '%')
+	    switch ((c = *f++))
+	      {
+	      case '%':
+		break;
+
+	      case 'l':
+		output_1_line (linbuf[from],
+			       (linbuf[from + 1]
+				- (linbuf[from + 1][-1] == '\n')),
+			       0, 0);
+		continue;
+
+	      case 'L':
+		output_1_line (linbuf[from], linbuf[from + 1], 0, 0);
+		continue;
+
+	      default:
+		f = do_printf_spec (out, f - 2, file, from, 0);
+		if (f)
+		  continue;
+		c = '%';
+		f = f1;
+		break;
+	      }
+
+	  putc (c, out);
+	}
+    }
+}
+
+static char const *
+do_printf_spec (FILE *out, char const *spec,
+		struct file_data const *file, lin n,
+		struct group const *groups)
+{
+  char const *f = spec;
+  char c;
+  char c1;
+
+  /* Scan printf-style SPEC of the form %[-'0]*[0-9]*(.[0-9]*)?[cdoxX].  */
+  /* assert (*f == '%'); */
+  f++;
+  while ((c = *f++) == '-' || c == '\'' || c == '0')
+    continue;
+  while (ISDIGIT (c))
+    c = *f++;
+  if (c == '.')
+    while (ISDIGIT (c = *f++))
+      continue;
+  c1 = *f++;
+
+  switch (c)
+    {
+    case 'c':
+      if (c1 != '\'')
+	return 0;
+      else
+	{
+	  char value IF_LINT (= 0);
+	  f = scan_char_literal (f, &value);
+	  if (!f)
+	    return 0;
+	  if (out)
+	    putc (value, out);
+	}
+      break;
+
+    case 'd': case 'o': case 'x': case 'X':
+      {
+	lin value;
+
+	if (file)
+	  {
+	    if (c1 != 'n')
+	      return 0;
+	    value = translate_line_number (file, n);
+	  }
+	else
+	  {
+	    value = groups_letter_value (groups, c1);
+	    if (value < 0)
+	      return 0;
+	  }
+
+	if (out)
+	  {
+	    /* For example, if the spec is "%3xn", use the printf
+	       format spec "%3lx".  Here the spec prefix is "%3".  */
+	    long int long_value = value;
+	    size_t spec_prefix_len = f - spec - 2;
+#if HAVE_C_VARARRAYS
+	    char format[spec_prefix_len + 3];
+#else
+	    char *format = xmalloc (spec_prefix_len + 3);
+#endif
+	    char *p = format + spec_prefix_len;
+	    memcpy (format, spec, spec_prefix_len);
+	    *p++ = 'l';
+	    *p++ = c;
+	    *p = '\0';
+	    fprintf (out, format, long_value);
+#if ! HAVE_C_VARARRAYS
+	    free (format);
+#endif
+	  }
+      }
+      break;
+
+    default:
+      return 0;
+    }
+
+  return f;
+}
+
+/* Scan the character literal represented in the string LIT; LIT points just
+   after the initial apostrophe.  Put the literal's value into *VALPTR.
+   Yield the address of the first character after the closing apostrophe,
+   or a null pointer if the literal is ill-formed.  */
+static char const *
+scan_char_literal (char const *lit, char *valptr)
+{
+  register char const *p = lit;
+  char value;
+  ptrdiff_t digits;
+  char c = *p++;
+
+  switch (c)
+    {
+      case 0:
+      case '\'':
+	return NULL;
+
+      case '\\':
+	value = 0;
+	while ((c = *p++) != '\'')
+	  {
+	    unsigned int digit = c - '0';
+	    if (8 <= digit)
+	      return NULL;
+	    value = 8 * value + digit;
+	  }
+	digits = p - lit - 2;
+	if (! (1 <= digits && digits <= 3))
+	  return NULL;
+	break;
+
+      default:
+	value = c;
+	if (*p++ != '\'')
+	  return NULL;
+	break;
+    }
+
+  *valptr = value;
+  return p;
+}
diff --git a/src/io.c b/src/io.c
new file mode 100644
index 0000000..0a75ab5
--- /dev/null
+++ b/src/io.c
@@ -0,0 +1,798 @@
+/* File I/O for GNU DIFF.
+
+   Copyright (C) 1988-1989, 1992-1995, 1998, 2001-2002, 2004, 2006, 2009-2011
+   Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "diff.h"
+#include <cmpbuf.h>
+#include <file-type.h>
+#include <xalloc.h>
+
+/* Rotate an unsigned value to the left.  */
+#define ROL(v, n) ((v) << (n) | (v) >> (sizeof (v) * CHAR_BIT - (n)))
+
+/* Given a hash value and a new character, return a new hash value.  */
+#define HASH(h, c) ((c) + ROL (h, 7))
+
+/* The type of a hash value.  */
+typedef size_t hash_value;
+verify (! TYPE_SIGNED (hash_value));
+
+/* Lines are put into equivalence classes of lines that match in lines_differ.
+   Each equivalence class is represented by one of these structures,
+   but only while the classes are being computed.
+   Afterward, each class is represented by a number.  */
+struct equivclass
+{
+  lin next;		/* Next item in this bucket.  */
+  hash_value hash;	/* Hash of lines in this class.  */
+  char const *line;	/* A line that fits this class.  */
+  size_t length;	/* That line's length, not counting its newline.  */
+};
+
+/* Hash-table: array of buckets, each being a chain of equivalence classes.
+   buckets[-1] is reserved for incomplete lines.  */
+static lin *buckets;
+
+/* Number of buckets in the hash table array, not counting buckets[-1].  */
+static size_t nbuckets;
+
+/* Array in which the equivalence classes are allocated.
+   The bucket-chains go through the elements in this array.
+   The number of an equivalence class is its index in this array.  */
+static struct equivclass *equivs;
+
+/* Index of first free element in the array `equivs'.  */
+static lin equivs_index;
+
+/* Number of elements allocated in the array `equivs'.  */
+static lin equivs_alloc;
+
+/* Read a block of data into a file buffer, checking for EOF and error.  */
+
+void
+file_block_read (struct file_data *current, size_t size)
+{
+  if (size && ! current->eof)
+    {
+      size_t s = block_read (current->desc,
+			     FILE_BUFFER (current) + current->buffered, size);
+      if (s == SIZE_MAX)
+	pfatal_with_name (current->name);
+      current->buffered += s;
+      current->eof = s < size;
+    }
+}
+
+/* Check for binary files and compare them for exact identity.  */
+
+/* Return 1 if BUF contains a non text character.
+   SIZE is the number of characters in BUF.  */
+
+#define binary_file_p(buf, size) (memchr (buf, 0, size) != 0)
+
+/* Get ready to read the current file.
+   Return nonzero if SKIP_TEST is zero,
+   and if it appears to be a binary file.  */
+
+static bool
+sip (struct file_data *current, bool skip_test)
+{
+  /* If we have a nonexistent file at this stage, treat it as empty.  */
+  if (current->desc < 0)
+    {
+      /* Leave room for a sentinel.  */
+      current->bufsize = sizeof (word);
+      current->buffer = xmalloc (current->bufsize);
+    }
+  else
+    {
+      current->bufsize = buffer_lcm (sizeof (word),
+				     STAT_BLOCKSIZE (current->stat),
+				     PTRDIFF_MAX - 2 * sizeof (word));
+      current->buffer = xmalloc (current->bufsize);
+
+      if (! skip_test)
+	{
+	  /* Check first part of file to see if it's a binary file.  */
+
+	  /* FIXME: if O_BINARY, this should revert to text mode
+	     if the file is not binary.  */
+
+	  file_block_read (current, current->bufsize);
+	  return binary_file_p (current->buffer, current->buffered);
+	}
+    }
+
+  current->buffered = 0;
+  current->eof = false;
+  return false;
+}
+
+/* Slurp the rest of the current file completely into memory.  */
+
+static void
+slurp (struct file_data *current)
+{
+  size_t cc;
+
+  if (current->desc < 0)
+    {
+      /* The file is nonexistent.  */
+      return;
+    }
+
+  if (S_ISREG (current->stat.st_mode))
+    {
+      /* It's a regular file; slurp in the rest all at once.  */
+
+      /* Get the size out of the stat block.
+	 Allocate just enough room for appended newline plus word sentinel,
+	 plus word-alignment since we want the buffer word-aligned.  */
+      size_t file_size = current->stat.st_size;
+      cc = file_size + 2 * sizeof (word) - file_size % sizeof (word);
+      if (file_size != current->stat.st_size || cc < file_size
+	  || PTRDIFF_MAX <= cc)
+	xalloc_die ();
+
+      if (current->bufsize < cc)
+	{
+	  current->bufsize = cc;
+	  current->buffer = xrealloc (current->buffer, cc);
+	}
+
+      /* Try to read at least 1 more byte than the size indicates, to
+	 detect whether the file is growing.  This is a nicety for
+	 users who run 'diff' on files while they are changing.  */
+
+      if (current->buffered <= file_size)
+	{
+	  file_block_read (current, file_size + 1 - current->buffered);
+	  if (current->buffered <= file_size)
+	    return;
+	}
+    }
+
+  /* It's not a regular file, or it's a growing regular file; read it,
+     growing the buffer as needed.  */
+
+  file_block_read (current, current->bufsize - current->buffered);
+
+  if (current->buffered)
+    {
+      while (current->buffered == current->bufsize)
+	{
+	  if (PTRDIFF_MAX / 2 - sizeof (word) < current->bufsize)
+	    xalloc_die ();
+	  current->bufsize *= 2;
+	  current->buffer = xrealloc (current->buffer, current->bufsize);
+	  file_block_read (current, current->bufsize - current->buffered);
+	}
+
+      /* Allocate just enough room for appended newline plus word
+	 sentinel, plus word-alignment.  */
+      cc = current->buffered + 2 * sizeof (word);
+      current->bufsize = cc - cc % sizeof (word);
+      current->buffer = xrealloc (current->buffer, current->bufsize);
+    }
+}
+
+/* Split the file into lines, simultaneously computing the equivalence
+   class for each line.  */
+
+static void
+find_and_hash_each_line (struct file_data *current)
+{
+  char const *p = current->prefix_end;
+  lin i, *bucket;
+  size_t length;
+
+  /* Cache often-used quantities in local variables to help the compiler.  */
+  char const **linbuf = current->linbuf;
+  lin alloc_lines = current->alloc_lines;
+  lin line = 0;
+  lin linbuf_base = current->linbuf_base;
+  lin *cureqs = xmalloc (alloc_lines * sizeof *cureqs);
+  struct equivclass *eqs = equivs;
+  lin eqs_index = equivs_index;
+  lin eqs_alloc = equivs_alloc;
+  char const *suffix_begin = current->suffix_begin;
+  char const *bufend = FILE_BUFFER (current) + current->buffered;
+  bool ig_case = ignore_case;
+  enum DIFF_white_space ig_white_space = ignore_white_space;
+  bool diff_length_compare_anyway =
+    ig_white_space != IGNORE_NO_WHITE_SPACE;
+  bool same_length_diff_contents_compare_anyway =
+    diff_length_compare_anyway | ig_case;
+
+  while (p < suffix_begin)
+    {
+      char const *ip = p;
+      hash_value h = 0;
+      unsigned char c;
+
+      /* Hash this line until we find a newline.  */
+      switch (ig_white_space)
+	{
+	case IGNORE_ALL_SPACE:
+	  while ((c = *p++) != '\n')
+	    if (! isspace (c))
+	      h = HASH (h, ig_case ? tolower (c) : c);
+	  break;
+
+	case IGNORE_SPACE_CHANGE:
+	  while ((c = *p++) != '\n')
+	    {
+	      if (isspace (c))
+		{
+		  do
+		    if ((c = *p++) == '\n')
+		      goto hashing_done;
+		  while (isspace (c));
+
+		  h = HASH (h, ' ');
+		}
+
+	      /* C is now the first non-space.  */
+	      h = HASH (h, ig_case ? tolower (c) : c);
+	    }
+	  break;
+
+	case IGNORE_TAB_EXPANSION:
+	case IGNORE_TAB_EXPANSION_AND_TRAILING_SPACE:
+	case IGNORE_TRAILING_SPACE:
+	  {
+	    size_t column = 0;
+	    while ((c = *p++) != '\n')
+	      {
+		if (ig_white_space & IGNORE_TRAILING_SPACE
+		    && isspace (c))
+		  {
+		    char const *p1 = p;
+		    unsigned char c1;
+		    do
+		      if ((c1 = *p1++) == '\n')
+			{
+			  p = p1;
+			  goto hashing_done;
+			}
+		    while (isspace (c1));
+		  }
+
+		size_t repetitions = 1;
+
+		if (ig_white_space & IGNORE_TAB_EXPANSION)
+		  switch (c)
+		    {
+		    case '\b':
+		      column -= 0 < column;
+		      break;
+
+		    case '\t':
+		      c = ' ';
+		      repetitions = tabsize - column % tabsize;
+		      column = (column + repetitions < column
+				? 0
+				: column + repetitions);
+		      break;
+
+		    case '\r':
+		      column = 0;
+		      break;
+
+		    default:
+		      column++;
+		      break;
+		    }
+
+		if (ig_case)
+		  c = tolower (c);
+
+		do
+		  h = HASH (h, c);
+		while (--repetitions != 0);
+	      }
+	  }
+	  break;
+
+	default:
+	  if (ig_case)
+	    while ((c = *p++) != '\n')
+	      h = HASH (h, tolower (c));
+	  else
+	    while ((c = *p++) != '\n')
+	      h = HASH (h, c);
+	  break;
+	}
+
+   hashing_done:;
+
+      bucket = &buckets[h % nbuckets];
+      length = p - ip - 1;
+
+      if (p == bufend
+	  && current->missing_newline
+	  && ROBUST_OUTPUT_STYLE (output_style))
+	{
+	  /* The last line is incomplete and we do not silently
+	     complete lines.  If the line cannot compare equal to any
+	     complete line, put it into buckets[-1] so that it can
+	     compare equal only to the other file's incomplete line
+	     (if one exists).  */
+	  if (ig_white_space < IGNORE_TRAILING_SPACE)
+	    bucket = &buckets[-1];
+	}
+
+      for (i = *bucket;  ;  i = eqs[i].next)
+	if (!i)
+	  {
+	    /* Create a new equivalence class in this bucket.  */
+	    i = eqs_index++;
+	    if (i == eqs_alloc)
+	      {
+		if (PTRDIFF_MAX / (2 * sizeof *eqs) <= eqs_alloc)
+		  xalloc_die ();
+		eqs_alloc *= 2;
+		eqs = xrealloc (eqs, eqs_alloc * sizeof *eqs);
+	      }
+	    eqs[i].next = *bucket;
+	    eqs[i].hash = h;
+	    eqs[i].line = ip;
+	    eqs[i].length = length;
+	    *bucket = i;
+	    break;
+	  }
+	else if (eqs[i].hash == h)
+	  {
+	    char const *eqline = eqs[i].line;
+
+	    /* Reuse existing class if lines_differ reports the lines
+               equal.  */
+	    if (eqs[i].length == length)
+	      {
+		/* Reuse existing equivalence class if the lines are identical.
+		   This detects the common case of exact identity
+		   faster than lines_differ would.  */
+		if (memcmp (eqline, ip, length) == 0)
+		  break;
+		if (!same_length_diff_contents_compare_anyway)
+		  continue;
+	      }
+	    else if (!diff_length_compare_anyway)
+	      continue;
+
+	    if (! lines_differ (eqline, ip))
+	      break;
+	  }
+
+      /* Maybe increase the size of the line table.  */
+      if (line == alloc_lines)
+	{
+	  /* Double (alloc_lines - linbuf_base) by adding to alloc_lines.  */
+	  if (PTRDIFF_MAX / 3 <= alloc_lines
+	      || PTRDIFF_MAX / sizeof *cureqs <= 2 * alloc_lines - linbuf_base
+	      || PTRDIFF_MAX / sizeof *linbuf <= alloc_lines - linbuf_base)
+	    xalloc_die ();
+	  alloc_lines = 2 * alloc_lines - linbuf_base;
+	  cureqs = xrealloc (cureqs, alloc_lines * sizeof *cureqs);
+	  linbuf += linbuf_base;
+	  linbuf = xrealloc (linbuf,
+			     (alloc_lines - linbuf_base) * sizeof *linbuf);
+	  linbuf -= linbuf_base;
+	}
+      linbuf[line] = ip;
+      cureqs[line] = i;
+      ++line;
+    }
+
+  current->buffered_lines = line;
+
+  for (i = 0;  ;  i++)
+    {
+      /* Record the line start for lines in the suffix that we care about.
+	 Record one more line start than lines,
+	 so that we can compute the length of any buffered line.  */
+      if (line == alloc_lines)
+	{
+	  /* Double (alloc_lines - linbuf_base) by adding to alloc_lines.  */
+	  if (PTRDIFF_MAX / 3 <= alloc_lines
+	      || PTRDIFF_MAX / sizeof *cureqs <= 2 * alloc_lines - linbuf_base
+	      || PTRDIFF_MAX / sizeof *linbuf <= alloc_lines - linbuf_base)
+	    xalloc_die ();
+	  alloc_lines = 2 * alloc_lines - linbuf_base;
+	  linbuf += linbuf_base;
+	  linbuf = xrealloc (linbuf,
+			     (alloc_lines - linbuf_base) * sizeof *linbuf);
+	  linbuf -= linbuf_base;
+	}
+      linbuf[line] = p;
+
+      if (p == bufend)
+	{
+	  /* If the last line is incomplete and we do not silently
+	     complete lines, don't count its appended newline.  */
+	  if (current->missing_newline && ROBUST_OUTPUT_STYLE (output_style))
+	    linbuf[line]--;
+	  break;
+	}
+
+      if (context <= i && no_diff_means_no_output)
+	break;
+
+      line++;
+
+      while (*p++ != '\n')
+	continue;
+    }
+
+  /* Done with cache in local variables.  */
+  current->linbuf = linbuf;
+  current->valid_lines = line;
+  current->alloc_lines = alloc_lines;
+  current->equivs = cureqs;
+  equivs = eqs;
+  equivs_alloc = eqs_alloc;
+  equivs_index = eqs_index;
+}
+
+/* Prepare the text.  Make sure the text end is initialized.
+   Make sure text ends in a newline,
+   but remember that we had to add one.
+   Strip trailing CRs, if that was requested.  */
+
+static void
+prepare_text (struct file_data *current)
+{
+  size_t buffered = current->buffered;
+  char *p = FILE_BUFFER (current);
+  char *dst;
+
+  if (buffered == 0 || p[buffered - 1] == '\n')
+    current->missing_newline = false;
+  else
+    {
+      p[buffered++] = '\n';
+      current->missing_newline = true;
+    }
+
+  if (!p)
+    return;
+
+  /* Don't use uninitialized storage when planting or using sentinels.  */
+  memset (p + buffered, 0, sizeof (word));
+
+  if (strip_trailing_cr && (dst = memchr (p, '\r', buffered)))
+    {
+      char const *src = dst;
+      char const *srclim = p + buffered;
+
+      do
+	dst += ! ((*dst = *src++) == '\r' && *src == '\n');
+      while (src < srclim);
+
+      buffered -= src - dst;
+    }
+
+  current->buffered = buffered;
+}
+
+/* We have found N lines in a buffer of size S; guess the
+   proportionate number of lines that will be found in a buffer of
+   size T.  However, do not guess a number of lines so large that the
+   resulting line table might cause overflow in size calculations.  */
+static lin
+guess_lines (lin n, size_t s, size_t t)
+{
+  size_t guessed_bytes_per_line = n < 10 ? 32 : s / (n - 1);
+  lin guessed_lines = MAX (1, t / guessed_bytes_per_line);
+  return MIN (guessed_lines, PTRDIFF_MAX / (2 * sizeof (char *) + 1) - 5) + 5;
+}
+
+/* Given a vector of two file_data objects, find the identical
+   prefixes and suffixes of each object.  */
+
+static void
+find_identical_ends (struct file_data filevec[])
+{
+  word *w0, *w1;
+  char *p0, *p1, *buffer0, *buffer1;
+  char const *end0, *beg0;
+  char const **linbuf0, **linbuf1;
+  lin i, lines;
+  size_t n0, n1;
+  lin alloc_lines0, alloc_lines1;
+  lin buffered_prefix, prefix_count, prefix_mask;
+  lin middle_guess, suffix_guess;
+
+  slurp (&filevec[0]);
+  prepare_text (&filevec[0]);
+  if (filevec[0].desc != filevec[1].desc)
+    {
+      slurp (&filevec[1]);
+      prepare_text (&filevec[1]);
+    }
+  else
+    {
+      filevec[1].buffer = filevec[0].buffer;
+      filevec[1].bufsize = filevec[0].bufsize;
+      filevec[1].buffered = filevec[0].buffered;
+      filevec[1].missing_newline = filevec[0].missing_newline;
+    }
+
+  /* Find identical prefix.  */
+
+  w0 = filevec[0].buffer;
+  w1 = filevec[1].buffer;
+  p0 = buffer0 = (char *) w0;
+  p1 = buffer1 = (char *) w1;
+  n0 = filevec[0].buffered;
+  n1 = filevec[1].buffered;
+
+  if (p0 == p1)
+    /* The buffers are the same; sentinels won't work.  */
+    p0 = p1 += n1;
+  else
+    {
+      /* Insert end sentinels, in this case characters that are guaranteed
+	 to make the equality test false, and thus terminate the loop.  */
+
+      if (n0 < n1)
+	p0[n0] = ~p1[n0];
+      else
+	p1[n1] = ~p0[n1];
+
+      /* Loop until first mismatch, or to the sentinel characters.  */
+
+      /* Compare a word at a time for speed.  */
+      while (*w0 == *w1)
+	w0++, w1++;
+
+      /* Do the last few bytes of comparison a byte at a time.  */
+      p0 = (char *) w0;
+      p1 = (char *) w1;
+      while (*p0 == *p1)
+	p0++, p1++;
+
+      /* Don't mistakenly count missing newline as part of prefix.  */
+      if (ROBUST_OUTPUT_STYLE (output_style)
+	  && ((buffer0 + n0 - filevec[0].missing_newline < p0)
+	      !=
+	      (buffer1 + n1 - filevec[1].missing_newline < p1)))
+	p0--, p1--;
+    }
+
+  /* Now P0 and P1 point at the first nonmatching characters.  */
+
+  /* Skip back to last line-beginning in the prefix,
+     and then discard up to HORIZON_LINES lines from the prefix.  */
+  i = horizon_lines;
+  while (p0 != buffer0 && (p0[-1] != '\n' || i--))
+    p0--, p1--;
+
+  /* Record the prefix.  */
+  filevec[0].prefix_end = p0;
+  filevec[1].prefix_end = p1;
+
+  /* Find identical suffix.  */
+
+  /* P0 and P1 point beyond the last chars not yet compared.  */
+  p0 = buffer0 + n0;
+  p1 = buffer1 + n1;
+
+  if (! ROBUST_OUTPUT_STYLE (output_style)
+      || filevec[0].missing_newline == filevec[1].missing_newline)
+    {
+      end0 = p0;	/* Addr of last char in file 0.  */
+
+      /* Get value of P0 at which we should stop scanning backward:
+	 this is when either P0 or P1 points just past the last char
+	 of the identical prefix.  */
+      beg0 = filevec[0].prefix_end + (n0 < n1 ? 0 : n0 - n1);
+
+      /* Scan back until chars don't match or we reach that point.  */
+      while (p0 != beg0)
+	if (*--p0 != *--p1)
+	  {
+	    /* Point at the first char of the matching suffix.  */
+	    ++p0, ++p1;
+	    beg0 = p0;
+	    break;
+	  }
+
+      /* Are we at a line-beginning in both files?  If not, add the rest of
+	 this line to the main body.  Discard up to HORIZON_LINES lines from
+	 the identical suffix.  Also, discard one extra line,
+	 because shift_boundaries may need it.  */
+      i = horizon_lines + !((buffer0 == p0 || p0[-1] == '\n')
+			    &&
+			    (buffer1 == p1 || p1[-1] == '\n'));
+      while (i-- && p0 != end0)
+	while (*p0++ != '\n')
+	  continue;
+
+      p1 += p0 - beg0;
+    }
+
+  /* Record the suffix.  */
+  filevec[0].suffix_begin = p0;
+  filevec[1].suffix_begin = p1;
+
+  /* Calculate number of lines of prefix to save.
+
+     prefix_count == 0 means save the whole prefix;
+     we need this for options like -D that output the whole file,
+     or for enormous contexts (to avoid worrying about arithmetic overflow).
+     We also need it for options like -F that output some preceding line;
+     at least we will need to find the last few lines,
+     but since we don't know how many, it's easiest to find them all.
+
+     Otherwise, prefix_count != 0.  Save just prefix_count lines at start
+     of the line buffer; they'll be moved to the proper location later.
+     Handle 1 more line than the context says (because we count 1 too many),
+     rounded up to the next power of 2 to speed index computation.  */
+
+  if (no_diff_means_no_output && ! function_regexp.fastmap
+      && context < LIN_MAX / 4 && context < n0)
+    {
+      middle_guess = guess_lines (0, 0, p0 - filevec[0].prefix_end);
+      suffix_guess = guess_lines (0, 0, buffer0 + n0 - p0);
+      for (prefix_count = 1;  prefix_count <= context;  prefix_count *= 2)
+	continue;
+      alloc_lines0 = (prefix_count + middle_guess
+		      + MIN (context, suffix_guess));
+    }
+  else
+    {
+      prefix_count = 0;
+      alloc_lines0 = guess_lines (0, 0, n0);
+    }
+
+  prefix_mask = prefix_count - 1;
+  lines = 0;
+  linbuf0 = xmalloc (alloc_lines0 * sizeof *linbuf0);
+  p0 = buffer0;
+
+  /* If the prefix is needed, find the prefix lines.  */
+  if (! (no_diff_means_no_output
+	 && filevec[0].prefix_end == p0
+	 && filevec[1].prefix_end == p1))
+    {
+      end0 = filevec[0].prefix_end;
+      while (p0 != end0)
+	{
+	  lin l = lines++ & prefix_mask;
+	  if (l == alloc_lines0)
+	    {
+	      if (PTRDIFF_MAX / (2 * sizeof *linbuf0) <= alloc_lines0)
+		xalloc_die ();
+	      alloc_lines0 *= 2;
+	      linbuf0 = xrealloc (linbuf0, alloc_lines0 * sizeof *linbuf0);
+	    }
+	  linbuf0[l] = p0;
+	  while (*p0++ != '\n')
+	    continue;
+	}
+    }
+  buffered_prefix = prefix_count && context < lines ? context : lines;
+
+  /* Allocate line buffer 1.  */
+
+  middle_guess = guess_lines (lines, p0 - buffer0, p1 - filevec[1].prefix_end);
+  suffix_guess = guess_lines (lines, p0 - buffer0, buffer1 + n1 - p1);
+  alloc_lines1 = buffered_prefix + middle_guess + MIN (context, suffix_guess);
+  if (alloc_lines1 < buffered_prefix
+      || PTRDIFF_MAX / sizeof *linbuf1 <= alloc_lines1)
+    xalloc_die ();
+  linbuf1 = xmalloc (alloc_lines1 * sizeof *linbuf1);
+
+  if (buffered_prefix != lines)
+    {
+      /* Rotate prefix lines to proper location.  */
+      for (i = 0;  i < buffered_prefix;  i++)
+	linbuf1[i] = linbuf0[(lines - context + i) & prefix_mask];
+      for (i = 0;  i < buffered_prefix;  i++)
+	linbuf0[i] = linbuf1[i];
+    }
+
+  /* Initialize line buffer 1 from line buffer 0.  */
+  for (i = 0; i < buffered_prefix; i++)
+    linbuf1[i] = linbuf0[i] - buffer0 + buffer1;
+
+  /* Record the line buffer, adjusted so that
+     linbuf[0] points at the first differing line.  */
+  filevec[0].linbuf = linbuf0 + buffered_prefix;
+  filevec[1].linbuf = linbuf1 + buffered_prefix;
+  filevec[0].linbuf_base = filevec[1].linbuf_base = - buffered_prefix;
+  filevec[0].alloc_lines = alloc_lines0 - buffered_prefix;
+  filevec[1].alloc_lines = alloc_lines1 - buffered_prefix;
+  filevec[0].prefix_lines = filevec[1].prefix_lines = lines;
+}
+
+/* If 1 < k, then (2**k - prime_offset[k]) is the largest prime less
+   than 2**k.  This table is derived from Chris K. Caldwell's list
+   <http://www.utm.edu/research/primes/lists/2small/>.  */
+
+static unsigned char const prime_offset[] =
+{
+  0, 0, 1, 1, 3, 1, 3, 1, 5, 3, 3, 9, 3, 1, 3, 19, 15, 1, 5, 1, 3, 9, 3,
+  15, 3, 39, 5, 39, 57, 3, 35, 1, 5, 9, 41, 31, 5, 25, 45, 7, 87, 21,
+  11, 57, 17, 55, 21, 115, 59, 81, 27, 129, 47, 111, 33, 55, 5, 13, 27,
+  55, 93, 1, 57, 25
+};
+
+/* Verify that this host's size_t is not too wide for the above table.  */
+
+verify (sizeof (size_t) * CHAR_BIT <= sizeof prime_offset);
+
+/* Given a vector of two file_data objects, read the file associated
+   with each one, and build the table of equivalence classes.
+   Return nonzero if either file appears to be a binary file.
+   If PRETEND_BINARY is nonzero, pretend they are binary regardless.  */
+
+bool
+read_files (struct file_data filevec[], bool pretend_binary)
+{
+  int i;
+  bool skip_test = text | pretend_binary;
+  bool appears_binary = pretend_binary | sip (&filevec[0], skip_test);
+
+  if (filevec[0].desc != filevec[1].desc)
+    appears_binary |= sip (&filevec[1], skip_test | appears_binary);
+  else
+    {
+      filevec[1].buffer = filevec[0].buffer;
+      filevec[1].bufsize = filevec[0].bufsize;
+      filevec[1].buffered = filevec[0].buffered;
+    }
+  if (appears_binary)
+    {
+      /* FIXME: If O_BINARY, this should set both files to binary mode.  */
+      return true;
+    }
+
+  find_identical_ends (filevec);
+
+  equivs_alloc = filevec[0].alloc_lines + filevec[1].alloc_lines + 1;
+  if (PTRDIFF_MAX / sizeof *equivs <= equivs_alloc)
+    xalloc_die ();
+  equivs = xmalloc (equivs_alloc * sizeof *equivs);
+  /* Equivalence class 0 is permanently safe for lines that were not
+     hashed.  Real equivalence classes start at 1.  */
+  equivs_index = 1;
+
+  /* Allocate (one plus) a prime number of hash buckets.  Use a prime
+     number between 1/3 and 2/3 of the value of equiv_allocs,
+     approximately.  */
+  for (i = 9; (size_t) 1 << i < equivs_alloc / 3; i++)
+    continue;
+  nbuckets = ((size_t) 1 << i) - prime_offset[i];
+  if (PTRDIFF_MAX / sizeof *buckets <= nbuckets)
+    xalloc_die ();
+  buckets = zalloc ((nbuckets + 1) * sizeof *buckets);
+  buckets++;
+
+  for (i = 0; i < 2; i++)
+    find_and_hash_each_line (&filevec[i]);
+
+  filevec[0].equiv_max = filevec[1].equiv_max = equivs_index;
+
+  free (equivs);
+  free (buckets - 1);
+
+  return false;
+}
diff --git a/src/normal.c b/src/normal.c
new file mode 100644
index 0000000..2c43b3b
--- /dev/null
+++ b/src/normal.c
@@ -0,0 +1,69 @@
+/* Normal-format output routines for GNU DIFF.
+
+   Copyright (C) 1988-1989, 1993, 1995, 1998, 2001, 2006, 2009-2011 Free
+   Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "diff.h"
+
+static void print_normal_hunk (struct change *);
+
+/* Print the edit-script SCRIPT as a normal diff.
+   INF points to an array of descriptions of the two files.  */
+
+void
+print_normal_script (struct change *script)
+{
+  print_script (script, find_change, print_normal_hunk);
+}
+
+/* Print a hunk of a normal diff.
+   This is a contiguous portion of a complete edit script,
+   describing changes in consecutive lines.  */
+
+static void
+print_normal_hunk (struct change *hunk)
+{
+  lin first0, last0, first1, last1;
+  register lin i;
+
+  /* Determine range of line numbers involved in each file.  */
+  enum changes changes = analyze_hunk (hunk, &first0, &last0, &first1, &last1);
+  if (!changes)
+    return;
+
+  begin_output ();
+
+  /* Print out the line number header for this hunk */
+  print_number_range (',', &files[0], first0, last0);
+  fputc (change_letter[changes], outfile);
+  print_number_range (',', &files[1], first1, last1);
+  fputc ('\n', outfile);
+
+  /* Print the lines that the first file has.  */
+  if (changes & OLD)
+    for (i = first0; i <= last0; i++)
+      print_1_line ("<", &files[0].linbuf[i]);
+
+  if (changes == CHANGED)
+    fputs ("---\n", outfile);
+
+  /* Print the lines that the second file has.  */
+  if (changes & NEW)
+    for (i = first1; i <= last1; i++)
+      print_1_line (">", &files[1].linbuf[i]);
+}
diff --git a/src/sdiff.c b/src/sdiff.c
new file mode 100644
index 0000000..e0b29f0
--- /dev/null
+++ b/src/sdiff.c
@@ -0,0 +1,1195 @@
+/* sdiff - side-by-side merge of file differences
+
+   Copyright (C) 1992-1996, 1998, 2001-2002, 2004, 2006-2007, 2009-2011 Free
+   Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "system.h"
+#include "paths.h"
+
+#include <stdio.h>
+#include <unlocked-io.h>
+
+#include <c-stack.h>
+#include <dirname.h>
+#include <error.h>
+#include <exitfail.h>
+#include <file-type.h>
+#include <getopt.h>
+#include <progname.h>
+#include <sh-quote.h>
+#include <version-etc.h>
+#include <xalloc.h>
+
+/* The official name of this program (e.g., no `g' prefix).  */
+#define PROGRAM_NAME "sdiff"
+
+#define AUTHORS \
+  proper_name ("Thomas Lord")
+
+/* Size of chunks read from files which must be parsed into lines.  */
+#define SDIFF_BUFSIZE ((size_t) 65536)
+
+static char const *editor_program = DEFAULT_EDITOR_PROGRAM;
+static char const **diffargv;
+
+static char * volatile tmpname;
+static FILE *tmp;
+
+#if HAVE_WORKING_FORK
+static pid_t volatile diffpid;
+#endif
+
+struct line_filter;
+
+static void catchsig (int);
+static bool edit (struct line_filter *, char const *, lin, lin, struct line_filter *, char const *, lin, lin, FILE *);
+static bool interact (struct line_filter *, struct line_filter *, char const *, struct line_filter *, char const *, FILE *);
+static void checksigs (void);
+static void diffarg (char const *);
+static void fatal (char const *) __attribute__((noreturn));
+static void perror_fatal (char const *) __attribute__((noreturn));
+static void trapsigs (void);
+static void untrapsig (int);
+
+#define NUM_SIGS (sizeof sigs / sizeof *sigs)
+static int const sigs[] = {
+#ifdef SIGHUP
+       SIGHUP,
+#endif
+#ifdef SIGQUIT
+       SIGQUIT,
+#endif
+#ifdef SIGTERM
+       SIGTERM,
+#endif
+#ifdef SIGXCPU
+       SIGXCPU,
+#endif
+#ifdef SIGXFSZ
+       SIGXFSZ,
+#endif
+#ifdef SIGPIPE
+       SIGPIPE,
+#endif
+       SIGINT
+#define handler_index_of_SIGINT (NUM_SIGS - 1)
+};
+
+#if HAVE_SIGACTION
+  /* Prefer `sigaction' if available, since `signal' can lose signals.  */
+  static struct sigaction initial_action[NUM_SIGS];
+# define initial_handler(i) (initial_action[i].sa_handler)
+  static void signal_handler (int, void (*) (int));
+#else
+  static void (*initial_action[NUM_SIGS]) ();
+# define initial_handler(i) (initial_action[i])
+# define signal_handler(sig, handler) signal (sig, handler)
+#endif
+
+static bool diraccess (char const *);
+static int temporary_file (void);
+
+/* Options: */
+
+/* Name of output file if -o specified.  */
+static char const *output;
+
+/* Do not print common lines.  */
+static bool suppress_common_lines;
+
+/* Value for the long option that does not have single-letter equivalents.  */
+enum
+{
+  DIFF_PROGRAM_OPTION = CHAR_MAX + 1,
+  HELP_OPTION,
+  STRIP_TRAILING_CR_OPTION,
+  TABSIZE_OPTION
+};
+
+static struct option const longopts[] =
+{
+  {"diff-program", 1, 0, DIFF_PROGRAM_OPTION},
+  {"expand-tabs", 0, 0, 't'},
+  {"help", 0, 0, HELP_OPTION},
+  {"ignore-all-space", 0, 0, 'W'}, /* swap W and w for historical reasons */
+  {"ignore-blank-lines", 0, 0, 'B'},
+  {"ignore-case", 0, 0, 'i'},
+  {"ignore-matching-lines", 1, 0, 'I'},
+  {"ignore-space-change", 0, 0, 'b'},
+  {"ignore-tab-expansion", 0, 0, 'E'},
+  {"ignore-trailing-space", 0, 0, 'Z'},
+  {"left-column", 0, 0, 'l'},
+  {"minimal", 0, 0, 'd'},
+  {"output", 1, 0, 'o'},
+  {"speed-large-files", 0, 0, 'H'},
+  {"strip-trailing-cr", 0, 0, STRIP_TRAILING_CR_OPTION},
+  {"suppress-common-lines", 0, 0, 's'},
+  {"tabsize", 1, 0, TABSIZE_OPTION},
+  {"text", 0, 0, 'a'},
+  {"version", 0, 0, 'v'},
+  {"width", 1, 0, 'w'},
+  {0, 0, 0, 0}
+};
+
+static void try_help (char const *, char const *) __attribute__((noreturn));
+static void
+try_help (char const *reason_msgid, char const *operand)
+{
+  if (reason_msgid)
+    error (0, 0, _(reason_msgid), operand);
+  error (EXIT_TROUBLE, 0, _("Try `%s --help' for more information."),
+	 program_name);
+  abort ();
+}
+
+static void
+check_stdout (void)
+{
+  if (ferror (stdout))
+    fatal ("write failed");
+  else if (fclose (stdout) != 0)
+    perror_fatal (_("standard output"));
+}
+
+static char const * const option_help_msgid[] = {
+  N_("-o, --output=FILE            operate interactively, sending output to FILE"),
+  "",
+  N_("-i, --ignore-case            consider upper- and lower-case to be the same"),
+  N_("-E, --ignore-tab-expansion   ignore changes due to tab expansion"),
+  N_("-Z, --ignore-trailing-space  ignore white space at line end"),
+  N_("-b, --ignore-space-change    ignore changes in the amount of white space"),
+  N_("-W, --ignore-all-space       ignore all white space"),
+  N_("-B, --ignore-blank-lines     ignore changes whose lines are all blank"),
+  N_("-I, --ignore-matching-lines=RE  ignore changes whose lines all match RE"),
+  N_("    --strip-trailing-cr      strip trailing carriage return on input"),
+  N_("-a, --text                   treat all files as text"),
+  "",
+  N_("-w, --width=NUM              output at most NUM (default 130) print columns"),
+  N_("-l, --left-column            output only the left column of common lines"),
+  N_("-s, --suppress-common-lines  do not output common lines"),
+  "",
+  N_("-t, --expand-tabs            expand tabs to spaces in output"),
+  N_("    --tabsize=NUM            tab stops at every NUM (default 8) print columns"),
+  "",
+  N_("-d, --minimal                try hard to find a smaller set of changes"),
+  N_("-H, --speed-large-files      assume large files, many scattered small changes"),
+  N_("    --diff-program=PROGRAM   use PROGRAM to compare files"),
+  "",
+  N_("    --help                   display this help and exit"),
+  N_("-v, --version                output version information and exit"),
+  0
+};
+
+static void
+usage (void)
+{
+  char const * const *p;
+
+  printf (_("Usage: %s [OPTION]... FILE1 FILE2\n"), program_name);
+  printf ("%s\n\n",
+          _("Side-by-side merge of differences between FILE1 and FILE2."));
+
+  fputs (_("\
+Mandatory arguments to long options are mandatory for short options too.\n\
+"), stdout);
+  for (p = option_help_msgid;  *p;  p++)
+    if (**p)
+      printf ("  %s\n", _(*p));
+    else
+      putchar ('\n');
+  printf ("\n%s\n%s\n",
+	  _("If a FILE is `-', read standard input."),
+	  _("Exit status is 0 if inputs are the same, 1 if different, 2 if trouble."));
+  emit_bug_reporting_address ();
+}
+
+/* Clean up after a signal or other failure.  This function is
+   async-signal-safe.  */
+static void
+cleanup (int signo __attribute__((unused)))
+{
+#if HAVE_WORKING_FORK
+  if (0 < diffpid)
+    kill (diffpid, SIGPIPE);
+#endif
+  if (tmpname)
+    unlink (tmpname);
+}
+
+static void exiterr (void) __attribute__((noreturn));
+static void
+exiterr (void)
+{
+  cleanup (0);
+  untrapsig (0);
+  checksigs ();
+  exit (EXIT_TROUBLE);
+}
+
+static void
+fatal (char const *msgid)
+{
+  error (0, 0, "%s", _(msgid));
+  exiterr ();
+}
+
+static void
+perror_fatal (char const *msg)
+{
+  int e = errno;
+  checksigs ();
+  error (0, e, "%s", msg);
+  exiterr ();
+}
+
+static void
+check_child_status (int werrno, int wstatus, int max_ok_status,
+		    char const *subsidiary_program)
+{
+  int status = (! werrno && WIFEXITED (wstatus)
+		? WEXITSTATUS (wstatus)
+		: INT_MAX);
+
+  if (max_ok_status < status)
+    {
+      error (0, werrno,
+	     _(status == 126
+	       ? "subsidiary program `%s' could not be invoked"
+	       : status == 127
+	       ? "subsidiary program `%s' not found"
+	       : status == INT_MAX
+	       ? "subsidiary program `%s' failed"
+	       : "subsidiary program `%s' failed (exit status %d)"),
+	     subsidiary_program, status);
+      exiterr ();
+    }
+}
+
+static FILE *
+ck_fopen (char const *fname, char const *type)
+{
+  FILE *r = fopen (fname, type);
+  if (! r)
+    perror_fatal (fname);
+  return r;
+}
+
+static void
+ck_fclose (FILE *f)
+{
+  if (fclose (f))
+    perror_fatal ("fclose");
+}
+
+static size_t
+ck_fread (char *buf, size_t size, FILE *f)
+{
+  size_t r = fread (buf, sizeof (char), size, f);
+  if (r == 0 && ferror (f))
+    perror_fatal (_("read failed"));
+  return r;
+}
+
+static void
+ck_fwrite (char const *buf, size_t size, FILE *f)
+{
+  if (fwrite (buf, sizeof (char), size, f) != size)
+    perror_fatal (_("write failed"));
+}
+
+static void
+ck_fflush (FILE *f)
+{
+  if (fflush (f) != 0)
+    perror_fatal (_("write failed"));
+}
+
+static char const *
+expand_name (char *name, bool is_dir, char const *other_name)
+{
+  if (STREQ (name, "-"))
+    fatal ("cannot interactively merge standard input");
+  if (! is_dir)
+    return name;
+  else
+    {
+      /* Yield NAME/BASE, where BASE is OTHER_NAME's basename.  */
+      char const *base = last_component (other_name);
+      size_t namelen = strlen (name), baselen = base_len (base);
+      bool insert_slash = *last_component (name) && name[namelen - 1] != '/';
+      char *r = xmalloc (namelen + insert_slash + baselen + 1);
+      memcpy (r, name, namelen);
+      r[namelen] = '/';
+      memcpy (r + namelen + insert_slash, base, baselen);
+      r[namelen + insert_slash + baselen] = '\0';
+      return r;
+    }
+}
+
+struct line_filter {
+  FILE *infile;
+  char *bufpos;
+  char *buffer;
+  char *buflim;
+};
+
+static void
+lf_init (struct line_filter *lf, FILE *infile)
+{
+  lf->infile = infile;
+  lf->bufpos = lf->buffer = lf->buflim = xmalloc (SDIFF_BUFSIZE + 1);
+  lf->buflim[0] = '\n';
+}
+
+/* Fill an exhausted line_filter buffer from its INFILE */
+static size_t
+lf_refill (struct line_filter *lf)
+{
+  size_t s = ck_fread (lf->buffer, SDIFF_BUFSIZE, lf->infile);
+  lf->bufpos = lf->buffer;
+  lf->buflim = lf->buffer + s;
+  lf->buflim[0] = '\n';
+  checksigs ();
+  return s;
+}
+
+/* Advance LINES on LF's infile, copying lines to OUTFILE */
+static void
+lf_copy (struct line_filter *lf, lin lines, FILE *outfile)
+{
+  char *start = lf->bufpos;
+
+  while (lines)
+    {
+      lf->bufpos = (char *) memchr (lf->bufpos, '\n', lf->buflim - lf->bufpos);
+      if (! lf->bufpos)
+	{
+	  ck_fwrite (start, lf->buflim - start, outfile);
+	  if (! lf_refill (lf))
+	    return;
+	  start = lf->bufpos;
+	}
+      else
+	{
+	  --lines;
+	  ++lf->bufpos;
+	}
+    }
+
+  ck_fwrite (start, lf->bufpos - start, outfile);
+}
+
+/* Advance LINES on LF's infile without doing output */
+static void
+lf_skip (struct line_filter *lf, lin lines)
+{
+  while (lines)
+    {
+      lf->bufpos = (char *) memchr (lf->bufpos, '\n', lf->buflim - lf->bufpos);
+      if (! lf->bufpos)
+	{
+	  if (! lf_refill (lf))
+	    break;
+	}
+      else
+	{
+	  --lines;
+	  ++lf->bufpos;
+	}
+    }
+}
+
+/* Snarf a line into a buffer.  Return EOF if EOF, 0 if error, 1 if OK.  */
+static int
+lf_snarf (struct line_filter *lf, char *buffer, size_t bufsize)
+{
+  for (;;)
+    {
+      char *start = lf->bufpos;
+      char *next = (char *) memchr (start, '\n', lf->buflim + 1 - start);
+      size_t s = next - start;
+      if (bufsize <= s)
+	return 0;
+      memcpy (buffer, start, s);
+      if (next < lf->buflim)
+	{
+	  buffer[s] = 0;
+	  lf->bufpos = next + 1;
+	  return 1;
+	}
+      if (! lf_refill (lf))
+	return s ? 0 : EOF;
+      buffer += s;
+      bufsize -= s;
+    }
+}
+
+int
+main (int argc, char *argv[])
+{
+  int opt;
+  char const *prog;
+
+  exit_failure = EXIT_TROUBLE;
+  initialize_main (&argc, &argv);
+  set_program_name (argv[0]);
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+  c_stack_action (cleanup);
+
+  prog = getenv ("EDITOR");
+  if (prog)
+    editor_program = prog;
+
+  diffarg (DEFAULT_DIFF_PROGRAM);
+
+  /* parse command line args */
+  while ((opt = getopt_long (argc, argv, "abBdEHiI:lo:stvw:WZ", longopts, 0))
+	 != -1)
+    {
+      switch (opt)
+	{
+	case 'a':
+	  diffarg ("-a");
+	  break;
+
+	case 'b':
+	  diffarg ("-b");
+	  break;
+
+	case 'B':
+	  diffarg ("-B");
+	  break;
+
+	case 'd':
+	  diffarg ("-d");
+	  break;
+
+	case 'E':
+	  diffarg ("-E");
+	  break;
+
+	case 'H':
+	  diffarg ("-H");
+	  break;
+
+	case 'i':
+	  diffarg ("-i");
+	  break;
+
+	case 'I':
+	  diffarg ("-I");
+	  diffarg (optarg);
+	  break;
+
+	case 'l':
+	  diffarg ("--left-column");
+	  break;
+
+	case 'o':
+	  output = optarg;
+	  break;
+
+	case 's':
+	  suppress_common_lines = true;
+	  break;
+
+	case 't':
+	  diffarg ("-t");
+	  break;
+
+	case 'v':
+	  version_etc (stdout, PROGRAM_NAME, PACKAGE_NAME, Version,
+		       AUTHORS, (char *) NULL);
+	  check_stdout ();
+	  return EXIT_SUCCESS;
+
+	case 'w':
+	  diffarg ("-W");
+	  diffarg (optarg);
+	  break;
+
+	case 'W':
+	  diffarg ("-w");
+	  break;
+
+	case 'Z':
+	  diffarg ("-Z");
+	  break;
+
+	case DIFF_PROGRAM_OPTION:
+	  diffargv[0] = optarg;
+	  break;
+
+	case HELP_OPTION:
+	  usage ();
+	  check_stdout ();
+	  return EXIT_SUCCESS;
+
+	case STRIP_TRAILING_CR_OPTION:
+	  diffarg ("--strip-trailing-cr");
+	  break;
+
+	case TABSIZE_OPTION:
+	  diffarg ("--tabsize");
+	  diffarg (optarg);
+	  break;
+
+	default:
+	  try_help (0, 0);
+	}
+    }
+
+  if (argc - optind != 2)
+    {
+      if (argc - optind < 2)
+	try_help ("missing operand after `%s'", argv[argc - 1]);
+      else
+	try_help ("extra operand `%s'", argv[optind + 2]);
+    }
+
+  if (! output)
+    {
+      /* easy case: diff does everything for us */
+      if (suppress_common_lines)
+	diffarg ("--suppress-common-lines");
+      diffarg ("-y");
+      diffarg ("--");
+      diffarg (argv[optind]);
+      diffarg (argv[optind + 1]);
+      diffarg (0);
+      execvp (diffargv[0], (char **) diffargv);
+      perror_fatal (diffargv[0]);
+    }
+  else
+    {
+      char const *lname, *rname;
+      FILE *left, *right, *out, *diffout;
+      bool interact_ok;
+      struct line_filter lfilt;
+      struct line_filter rfilt;
+      struct line_filter diff_filt;
+      bool leftdir = diraccess (argv[optind]);
+      bool rightdir = diraccess (argv[optind + 1]);
+
+      if (leftdir & rightdir)
+	fatal ("both files to be compared are directories");
+
+      lname = expand_name (argv[optind], leftdir, argv[optind + 1]);
+      left = ck_fopen (lname, "r");
+      rname = expand_name (argv[optind + 1], rightdir, argv[optind]);
+      right = ck_fopen (rname, "r");
+      out = ck_fopen (output, "w");
+
+      diffarg ("--sdiff-merge-assist");
+      diffarg ("--");
+      diffarg (argv[optind]);
+      diffarg (argv[optind + 1]);
+      diffarg (0);
+
+      trapsigs ();
+
+#if ! HAVE_WORKING_FORK
+      {
+	size_t cmdsize = 1;
+	char *p, *command;
+	int i;
+
+	for (i = 0;  diffargv[i];  i++)
+	  cmdsize += shell_quote_length (diffargv[i]) + 1;
+	command = p = xmalloc (cmdsize);
+	for (i = 0;  diffargv[i];  i++)
+	  {
+	    p = shell_quote_copy (p, diffargv[i]);
+	    *p++ = ' ';
+	  }
+	p[-1] = 0;
+	errno = 0;
+	diffout = popen (command, "r");
+	if (! diffout)
+	  perror_fatal (command);
+	free (command);
+      }
+#else
+      {
+	int diff_fds[2];
+
+	if (pipe (diff_fds) != 0)
+	  perror_fatal ("pipe");
+
+	diffpid = fork ();
+	if (diffpid < 0)
+	  perror_fatal ("fork");
+	if (! diffpid)
+	  {
+	    /* Alter the child's SIGINT and SIGPIPE handlers;
+	       this may munge the parent.
+	       The child ignores SIGINT in case the user interrupts the editor.
+	       The child does not ignore SIGPIPE, even if the parent does.  */
+	    if (initial_handler (handler_index_of_SIGINT) != SIG_IGN)
+	      signal_handler (SIGINT, SIG_IGN);
+	    signal_handler (SIGPIPE, SIG_DFL);
+	    close (diff_fds[0]);
+	    if (diff_fds[1] != STDOUT_FILENO)
+	      {
+		dup2 (diff_fds[1], STDOUT_FILENO);
+		close (diff_fds[1]);
+	      }
+
+	    execvp (diffargv[0], (char **) diffargv);
+	    _exit (errno == ENOENT ? 127 : 126);
+	  }
+
+	close (diff_fds[1]);
+	diffout = fdopen (diff_fds[0], "r");
+	if (! diffout)
+	  perror_fatal ("fdopen");
+      }
+#endif
+
+      lf_init (&diff_filt, diffout);
+      lf_init (&lfilt, left);
+      lf_init (&rfilt, right);
+
+      interact_ok = interact (&diff_filt, &lfilt, lname, &rfilt, rname, out);
+
+      ck_fclose (left);
+      ck_fclose (right);
+      ck_fclose (out);
+
+      {
+	int wstatus;
+	int werrno = 0;
+
+#if ! HAVE_WORKING_FORK
+	wstatus = pclose (diffout);
+	if (wstatus == -1)
+	  werrno = errno;
+#else
+	ck_fclose (diffout);
+	while (waitpid (diffpid, &wstatus, 0) < 0)
+	  if (errno == EINTR)
+	    checksigs ();
+	  else
+	    perror_fatal ("waitpid");
+	diffpid = 0;
+#endif
+
+	if (tmpname)
+	  {
+	    unlink (tmpname);
+	    tmpname = 0;
+	  }
+
+	if (! interact_ok)
+	  exiterr ();
+
+	check_child_status (werrno, wstatus, EXIT_FAILURE, diffargv[0]);
+	untrapsig (0);
+	checksigs ();
+	exit (WEXITSTATUS (wstatus));
+      }
+    }
+  return EXIT_SUCCESS;			/* Fool `-Wall'.  */
+}
+
+static void
+diffarg (char const *a)
+{
+  static size_t diffargs, diffarglim;
+
+  if (diffargs == diffarglim)
+    {
+      if (! diffarglim)
+	diffarglim = 16;
+      else if (PTRDIFF_MAX / (2 * sizeof *diffargv) <= diffarglim)
+	xalloc_die ();
+      else
+	diffarglim *= 2;
+      diffargv = xrealloc (diffargv, diffarglim * sizeof *diffargv);
+    }
+  diffargv[diffargs++] = a;
+}
+
+/* Signal handling */
+
+static bool volatile ignore_SIGINT;
+static int volatile signal_received;
+static bool sigs_trapped;
+
+static void
+catchsig (int s)
+{
+#if ! HAVE_SIGACTION
+  signal (s, SIG_IGN);
+#endif
+  if (! (s == SIGINT && ignore_SIGINT))
+    signal_received = s;
+}
+
+#if HAVE_SIGACTION
+static struct sigaction catchaction;
+
+static void
+signal_handler (int sig, void (*handler) (int))
+{
+  catchaction.sa_handler = handler;
+  sigaction (sig, &catchaction, 0);
+}
+#endif
+
+static void
+trapsigs (void)
+{
+  int i;
+
+#if HAVE_SIGACTION
+  catchaction.sa_flags = SA_RESTART;
+  sigemptyset (&catchaction.sa_mask);
+  for (i = 0;  i < NUM_SIGS;  i++)
+    sigaddset (&catchaction.sa_mask, sigs[i]);
+#endif
+
+  for (i = 0;  i < NUM_SIGS;  i++)
+    {
+#if HAVE_SIGACTION
+      sigaction (sigs[i], 0, &initial_action[i]);
+#else
+      initial_action[i] = signal (sigs[i], SIG_IGN);
+#endif
+      if (initial_handler (i) != SIG_IGN)
+	signal_handler (sigs[i], catchsig);
+    }
+
+#ifdef SIGCHLD
+  /* System V fork+wait does not work if SIGCHLD is ignored.  */
+  signal (SIGCHLD, SIG_DFL);
+#endif
+
+  sigs_trapped = true;
+}
+
+/* Untrap signal S, or all trapped signals if S is zero.  */
+static void
+untrapsig (int s)
+{
+  int i;
+
+  if (sigs_trapped)
+    for (i = 0;  i < NUM_SIGS;  i++)
+      if ((! s || sigs[i] == s)  &&  initial_handler (i) != SIG_IGN)
+	{
+#if HAVE_SIGACTION
+	  sigaction (sigs[i], &initial_action[i], 0);
+#else
+	  signal (sigs[i], initial_action[i]);
+#endif
+	}
+}
+
+/* Exit if a signal has been received.  */
+static void
+checksigs (void)
+{
+  int s = signal_received;
+  if (s)
+    {
+      cleanup (0);
+
+      /* Yield an exit status indicating that a signal was received.  */
+      untrapsig (s);
+      kill (getpid (), s);
+
+      /* That didn't work, so exit with error status.  */
+      exit (EXIT_TROUBLE);
+    }
+}
+
+static void
+give_help (void)
+{
+  fprintf (stderr, "%s", _("\
+ed:\tEdit then use both versions, each decorated with a header.\n\
+eb:\tEdit then use both versions.\n\
+el or e1:\tEdit then use the left version.\n\
+er or e2:\tEdit then use the right version.\n\
+e:\tDiscard both versions then edit a new one.\n\
+l or 1:\tUse the left version.\n\
+r or 2:\tUse the right version.\n\
+s:\tSilently include common lines.\n\
+v:\tVerbosely include common lines.\n\
+q:\tQuit.\n\
+"));
+}
+
+static int
+skip_white (void)
+{
+  int c;
+  for (;;)
+    {
+      c = getchar ();
+      if (! isspace (c) || c == '\n')
+	break;
+      checksigs ();
+    }
+  if (ferror (stdin))
+    perror_fatal (_("read failed"));
+  return c;
+}
+
+static void
+flush_line (void)
+{
+  int c;
+  while ((c = getchar ()) != '\n' && c != EOF)
+    continue;
+  if (ferror (stdin))
+    perror_fatal (_("read failed"));
+}
+
+
+/* interpret an edit command */
+static bool
+edit (struct line_filter *left, char const *lname, lin lline, lin llen,
+      struct line_filter *right, char const *rname, lin rline, lin rlen,
+      FILE *outfile)
+{
+  for (;;)
+    {
+      int cmd0 IF_LINT (= 0);
+      int cmd1 IF_LINT (= 0);
+      bool gotcmd = false;
+
+      while (! gotcmd)
+	{
+	  if (putchar ('%') != '%')
+	    perror_fatal (_("write failed"));
+	  ck_fflush (stdout);
+
+	  cmd0 = skip_white ();
+	  switch (cmd0)
+	    {
+	    case '1': case '2': case 'l': case 'r':
+	    case 's': case 'v': case 'q':
+	      if (skip_white () != '\n')
+		{
+		  give_help ();
+		  flush_line ();
+		  continue;
+		}
+	      gotcmd = true;
+	      break;
+
+	    case 'e':
+	      cmd1 = skip_white ();
+	      switch (cmd1)
+		{
+		case '1': case '2': case 'b': case 'd': case 'l': case 'r':
+		  if (skip_white () != '\n')
+		    {
+		      give_help ();
+		      flush_line ();
+		      continue;
+		    }
+		  gotcmd = true;
+		  break;
+		case '\n':
+		  gotcmd = true;
+		  break;
+		default:
+		  give_help ();
+		  flush_line ();
+		  continue;
+		}
+	      break;
+
+	    case EOF:
+	      if (feof (stdin))
+		{
+		  gotcmd = true;
+		  cmd0 = 'q';
+		  break;
+		}
+	      /* Fall through.  */
+	    default:
+	      flush_line ();
+	      /* Fall through.  */
+	    case '\n':
+	      give_help ();
+	      continue;
+	    }
+	}
+
+      switch (cmd0)
+	{
+	case '1': case 'l':
+	  lf_copy (left, llen, outfile);
+	  lf_skip (right, rlen);
+	  return true;
+	case '2': case 'r':
+	  lf_copy (right, rlen, outfile);
+	  lf_skip (left, llen);
+	  return true;
+	case 's':
+	  suppress_common_lines = true;
+	  break;
+	case 'v':
+	  suppress_common_lines = false;
+	  break;
+	case 'q':
+	  return false;
+	case 'e':
+	  {
+	    int fd;
+
+	    if (tmpname)
+	      tmp = fopen (tmpname, "w");
+	    else
+	      {
+		if ((fd = temporary_file ()) < 0)
+		  perror_fatal ("mkstemp");
+		tmp = fdopen (fd, "w");
+	      }
+
+	    if (! tmp)
+	      perror_fatal (tmpname);
+
+	    switch (cmd1)
+	      {
+	      case 'd':
+		if (llen)
+		  {
+		    if (llen == 1)
+		      fprintf (tmp, "--- %s %ld\n", lname, (long int) lline);
+		    else
+		      fprintf (tmp, "--- %s %ld,%ld\n", lname,
+			       (long int) lline,
+			       (long int) (lline + llen - 1));
+		  }
+		/* Fall through.  */
+	      case '1': case 'b': case 'l':
+		lf_copy (left, llen, tmp);
+		break;
+
+	      default:
+		lf_skip (left, llen);
+		break;
+	      }
+
+	    switch (cmd1)
+	      {
+	      case 'd':
+		if (rlen)
+		  {
+		    if (rlen == 1)
+		      fprintf (tmp, "+++ %s %ld\n", rname, (long int) rline);
+		    else
+		      fprintf (tmp, "+++ %s %ld,%ld\n", rname,
+			       (long int) rline,
+			       (long int) (rline + rlen - 1));
+		  }
+		/* Fall through.  */
+	      case '2': case 'b': case 'r':
+		lf_copy (right, rlen, tmp);
+		break;
+
+	      default:
+		lf_skip (right, rlen);
+		break;
+	      }
+
+	    ck_fclose (tmp);
+
+	    {
+	      int wstatus;
+	      int werrno = 0;
+	      ignore_SIGINT = true;
+	      checksigs ();
+
+	      {
+#if ! HAVE_WORKING_FORK
+		char *command =
+		  xmalloc (shell_quote_length (editor_program)
+			   + 1 + strlen (tmpname) + 1);
+		sprintf (shell_quote_copy (command, editor_program),
+			 " %s", tmpname);
+		wstatus = system (command);
+		if (wstatus == -1)
+		  werrno = errno;
+		free (command);
+#else
+		pid_t pid;
+
+		pid = fork ();
+		if (pid == 0)
+		  {
+		    char const *argv[3];
+		    int i = 0;
+
+		    argv[i++] = editor_program;
+		    argv[i++] = tmpname;
+		    argv[i] = 0;
+
+		    execvp (editor_program, (char **) argv);
+		    _exit (errno == ENOENT ? 127 : 126);
+		  }
+
+		if (pid < 0)
+		  perror_fatal ("fork");
+
+		while (waitpid (pid, &wstatus, 0) < 0)
+		  if (errno == EINTR)
+		    checksigs ();
+		  else
+		    perror_fatal ("waitpid");
+#endif
+	      }
+
+	      ignore_SIGINT = false;
+	      check_child_status (werrno, wstatus, EXIT_SUCCESS,
+				  editor_program);
+	    }
+
+	    {
+	      char buf[SDIFF_BUFSIZE];
+	      size_t size;
+	      tmp = ck_fopen (tmpname, "r");
+	      while ((size = ck_fread (buf, SDIFF_BUFSIZE, tmp)) != 0)
+		{
+		  checksigs ();
+		  ck_fwrite (buf, size, outfile);
+		}
+	      ck_fclose (tmp);
+	    }
+	    return true;
+	  }
+	default:
+	  give_help ();
+	  break;
+	}
+    }
+}
+
+/* Alternately reveal bursts of diff output and handle user commands.  */
+static bool
+interact (struct line_filter *diff,
+	  struct line_filter *left, char const *lname,
+	  struct line_filter *right, char const *rname,
+	  FILE *outfile)
+{
+  lin lline = 1, rline = 1;
+
+  for (;;)
+    {
+      char diff_help[256];
+      int snarfed = lf_snarf (diff, diff_help, sizeof diff_help);
+
+      if (snarfed <= 0)
+	return snarfed != 0;
+
+      checksigs ();
+
+      if (diff_help[0] == ' ')
+	puts (diff_help + 1);
+      else
+	{
+	  char *numend;
+	  uintmax_t val;
+	  lin llen, rlen, lenmax;
+	  errno = 0;
+	  llen = val = strtoumax (diff_help + 1, &numend, 10);
+	  if (llen < 0 || llen != val || errno || *numend != ',')
+	    fatal (diff_help);
+	  rlen = val = strtoumax (numend + 1, &numend, 10);
+	  if (rlen < 0 || rlen != val || errno || *numend)
+	    fatal (diff_help);
+
+	  lenmax = MAX (llen, rlen);
+
+	  switch (diff_help[0])
+	    {
+	    case 'i':
+	      if (suppress_common_lines)
+		lf_skip (diff, lenmax);
+	      else
+		lf_copy (diff, lenmax, stdout);
+
+	      lf_copy (left, llen, outfile);
+	      lf_skip (right, rlen);
+	      break;
+
+	    case 'c':
+	      lf_copy (diff, lenmax, stdout);
+	      if (! edit (left, lname, lline, llen,
+			  right, rname, rline, rlen,
+			  outfile))
+		return false;
+	      break;
+
+	    default:
+	      fatal (diff_help);
+	    }
+
+	  lline += llen;
+	  rline += rlen;
+	}
+    }
+}
+
+/* Return true if DIR is an existing directory.  */
+static bool
+diraccess (char const *dir)
+{
+  struct stat buf;
+  return stat (dir, &buf) == 0 && S_ISDIR (buf.st_mode);
+}
+
+#ifndef P_tmpdir
+# define P_tmpdir "/tmp"
+#endif
+#ifndef TMPDIR_ENV
+# define TMPDIR_ENV "TMPDIR"
+#endif
+
+/* Open a temporary file and return its file descriptor.  Put into
+   tmpname the address of a newly allocated buffer that holds the
+   file's name.  Use the prefix "sdiff".  */
+static int
+temporary_file (void)
+{
+  char const *tmpdir = getenv (TMPDIR_ENV);
+  char const *dir = tmpdir ? tmpdir : P_tmpdir;
+  char *buf = xmalloc (strlen (dir) + 1 + 5 + 6 + 1);
+  int fd;
+  int e;
+  sigset_t procmask;
+  sigset_t blocked;
+  sprintf (buf, "%s/sdiffXXXXXX", dir);
+  sigemptyset (&blocked);
+  sigaddset (&blocked, SIGINT);
+  sigprocmask (SIG_BLOCK, &blocked, &procmask);
+  fd = mkstemp (buf);
+  e = errno;
+  if (0 <= fd)
+    tmpname = buf;
+  sigprocmask (SIG_SETMASK, &procmask, 0);
+  errno = e;
+  return fd;
+}
diff --git a/src/side.c b/src/side.c
new file mode 100644
index 0000000..e435856
--- /dev/null
+++ b/src/side.c
@@ -0,0 +1,320 @@
+/* sdiff-format output routines for GNU DIFF.
+
+   Copyright (C) 1991-1993, 1998, 2001-2002, 2004, 2009-2011 Free Software
+   Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   GNU DIFF is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY.  No author or distributor
+   accepts responsibility to anyone for the consequences of using it
+   or for whether it serves any particular purpose or works at all,
+   unless he says so in writing.  Refer to the GNU General Public
+   License for full details.
+
+   Everyone is granted permission to copy, modify and redistribute
+   GNU DIFF, but only under the conditions described in the
+   GNU General Public License.   A copy of this license is
+   supposed to have been given to you along with GNU DIFF so you
+   can know your rights and responsibilities.  It should be in a
+   file named COPYING.  Among other things, the copyright notice
+   and this notice must be preserved on all copies.  */
+
+#include "diff.h"
+
+#include <wchar.h>
+
+static void print_sdiff_common_lines (lin, lin);
+static void print_sdiff_hunk (struct change *);
+
+/* Next line number to be printed in the two input files.  */
+static lin next0, next1;
+
+/* Print the edit-script SCRIPT as a sdiff style output.  */
+
+void
+print_sdiff_script (struct change *script)
+{
+  begin_output ();
+
+  next0 = next1 = - files[0].prefix_lines;
+  print_script (script, find_change, print_sdiff_hunk);
+
+  print_sdiff_common_lines (files[0].valid_lines, files[1].valid_lines);
+}
+
+/* Tab from column FROM to column TO, where FROM <= TO.  Yield TO.  */
+
+static size_t
+tab_from_to (size_t from, size_t to)
+{
+  FILE *out = outfile;
+  size_t tab;
+  size_t tab_size = tabsize;
+
+  if (!expand_tabs)
+    for (tab = from + tab_size - from % tab_size;  tab <= to;  tab += tab_size)
+      {
+	putc ('\t', out);
+	from = tab;
+      }
+  while (from++ < to)
+    putc (' ', out);
+  return to;
+}
+
+/* Print the text for half an sdiff line.  This means truncate to
+   width observing tabs, and trim a trailing newline.  Return the
+   last column written (not the number of chars).  */
+
+static size_t
+print_half_line (char const *const *line, size_t indent, size_t out_bound)
+{
+  FILE *out = outfile;
+  register size_t in_position = 0;
+  register size_t out_position = 0;
+  register char const *text_pointer = line[0];
+  register char const *text_limit = line[1];
+  mbstate_t mbstate = { 0 };
+
+  while (text_pointer < text_limit)
+    {
+      char const *tp0 = text_pointer;
+      register char c = *text_pointer++;
+
+      switch (c)
+	{
+	case '\t':
+	  {
+	    size_t spaces = tabsize - in_position % tabsize;
+	    if (in_position == out_position)
+	      {
+		size_t tabstop = out_position + spaces;
+		if (expand_tabs)
+		  {
+		    if (out_bound < tabstop)
+		      tabstop = out_bound;
+		    for (;  out_position < tabstop;  out_position++)
+		      putc (' ', out);
+		  }
+		else
+		  if (tabstop < out_bound)
+		    {
+		      out_position = tabstop;
+		      putc (c, out);
+		    }
+	      }
+	    in_position += spaces;
+	  }
+	  break;
+
+	case '\r':
+	  {
+	    putc (c, out);
+	    tab_from_to (0, indent);
+	    in_position = out_position = 0;
+	  }
+	  break;
+
+	case '\b':
+	  if (in_position != 0 && --in_position < out_bound)
+	    {
+	      if (out_position <= in_position)
+		/* Add spaces to make up for suppressed tab past out_bound.  */
+		for (;  out_position < in_position;  out_position++)
+		  putc (' ', out);
+	      else
+		{
+		  out_position = in_position;
+		  putc (c, out);
+		}
+	    }
+	  break;
+
+	default:
+	  {
+	    wchar_t wc;
+	    size_t bytes = mbrtowc (&wc, tp0, text_limit - tp0, &mbstate);
+
+	    if (0 < bytes && bytes < (size_t) -2)
+	      {
+		int width = wcwidth (wc);
+		if (0 < width)
+		  in_position += width;
+		if (in_position <= out_bound)
+		  {
+		    out_position = in_position;
+		    fwrite (tp0, 1, bytes, stdout);
+		  }
+		text_pointer = tp0 + bytes;
+		break;
+	      }
+	  }
+	  /* Fall through.  */
+	case '\f':
+	case '\v':
+	  if (in_position < out_bound)
+	    putc (c, out);
+	  break;
+
+	case ' ': case '!': case '"': case '#': case '%':
+	case '&': case '\'': case '(': case ')': case '*':
+	case '+': case ',': case '-': case '.': case '/':
+	case '0': case '1': case '2': case '3': case '4':
+	case '5': case '6': case '7': case '8': case '9':
+	case ':': case ';': case '<': case '=': case '>':
+	case '?':
+	case 'A': case 'B': case 'C': case 'D': case 'E':
+	case 'F': case 'G': case 'H': case 'I': case 'J':
+	case 'K': case 'L': case 'M': case 'N': case 'O':
+	case 'P': case 'Q': case 'R': case 'S': case 'T':
+	case 'U': case 'V': case 'W': case 'X': case 'Y':
+	case 'Z':
+	case '[': case '\\': case ']': case '^': case '_':
+	case 'a': case 'b': case 'c': case 'd': case 'e':
+	case 'f': case 'g': case 'h': case 'i': case 'j':
+	case 'k': case 'l': case 'm': case 'n': case 'o':
+	case 'p': case 'q': case 'r': case 's': case 't':
+	case 'u': case 'v': case 'w': case 'x': case 'y':
+	case 'z': case '{': case '|': case '}': case '~':
+	  /* These characters are printable ASCII characters.  */
+	  if (in_position++ < out_bound)
+	    {
+	      out_position = in_position;
+	      putc (c, out);
+	    }
+	  break;
+
+	case '\n':
+	  return out_position;
+	}
+    }
+
+  return out_position;
+}
+
+/* Print side by side lines with a separator in the middle.
+   0 parameters are taken to indicate white space text.
+   Blank lines that can easily be caught are reduced to a single newline.  */
+
+static void
+print_1sdiff_line (char const *const *left, char sep,
+		   char const *const *right)
+{
+  FILE *out = outfile;
+  size_t hw = sdiff_half_width;
+  size_t c2o = sdiff_column2_offset;
+  size_t col = 0;
+  bool put_newline = false;
+
+  if (left)
+    {
+      put_newline |= left[1][-1] == '\n';
+      col = print_half_line (left, 0, hw);
+    }
+
+  if (sep != ' ')
+    {
+      col = tab_from_to (col, (hw + c2o - 1) / 2) + 1;
+      if (sep == '|' && put_newline != (right[1][-1] == '\n'))
+	sep = put_newline ? '/' : '\\';
+      putc (sep, out);
+    }
+
+  if (right)
+    {
+      put_newline |= right[1][-1] == '\n';
+      if (**right != '\n')
+	{
+	  col = tab_from_to (col, c2o);
+	  print_half_line (right, col, hw);
+	}
+    }
+
+  if (put_newline)
+    putc ('\n', out);
+}
+
+/* Print lines common to both files in side-by-side format.  */
+static void
+print_sdiff_common_lines (lin limit0, lin limit1)
+{
+  lin i0 = next0, i1 = next1;
+
+  if (!suppress_common_lines && (i0 != limit0 || i1 != limit1))
+    {
+      if (sdiff_merge_assist)
+	{
+	  long int len0 = limit0 - i0;
+	  long int len1 = limit1 - i1;
+	  fprintf (outfile, "i%ld,%ld\n", len0, len1);
+	}
+
+      if (!left_column)
+	{
+	  while (i0 != limit0 && i1 != limit1)
+	    print_1sdiff_line (&files[0].linbuf[i0++], ' ',
+			       &files[1].linbuf[i1++]);
+	  while (i1 != limit1)
+	    print_1sdiff_line (0, ')', &files[1].linbuf[i1++]);
+	}
+      while (i0 != limit0)
+	print_1sdiff_line (&files[0].linbuf[i0++], '(', 0);
+    }
+
+  next0 = limit0;
+  next1 = limit1;
+}
+
+/* Print a hunk of an sdiff diff.
+   This is a contiguous portion of a complete edit script,
+   describing changes in consecutive lines.  */
+
+static void
+print_sdiff_hunk (struct change *hunk)
+{
+  lin first0, last0, first1, last1;
+  register lin i, j;
+
+  /* Determine range of line numbers involved in each file.  */
+  enum changes changes =
+    analyze_hunk (hunk, &first0, &last0, &first1, &last1);
+  if (!changes)
+    return;
+
+  /* Print out lines up to this change.  */
+  print_sdiff_common_lines (first0, first1);
+
+  if (sdiff_merge_assist)
+    {
+      long int len0 = last0 - first0 + 1;
+      long int len1 = last1 - first1 + 1;
+      fprintf (outfile, "c%ld,%ld\n", len0, len1);
+    }
+
+  /* Print ``xxx  |  xxx '' lines */
+  if (changes == CHANGED)
+    {
+      for (i = first0, j = first1;  i <= last0 && j <= last1;  i++, j++)
+	print_1sdiff_line (&files[0].linbuf[i], '|', &files[1].linbuf[j]);
+      changes = (i <= last0 ? OLD : 0) + (j <= last1 ? NEW : 0);
+      next0 = first0 = i;
+      next1 = first1 = j;
+    }
+
+  /* Print ``     >  xxx '' lines */
+  if (changes & NEW)
+    {
+      for (j = first1; j <= last1; ++j)
+	print_1sdiff_line (0, '>', &files[1].linbuf[j]);
+      next1 = j;
+    }
+
+  /* Print ``xxx  <     '' lines */
+  if (changes & OLD)
+    {
+      for (i = first0; i <= last0; ++i)
+	print_1sdiff_line (&files[0].linbuf[i], '<', 0);
+      next0 = i;
+    }
+}
diff --git a/src/system.h b/src/system.h
new file mode 100644
index 0000000..594ef6e
--- /dev/null
+++ b/src/system.h
@@ -0,0 +1,207 @@
+/* System dependent declarations.
+
+   Copyright (C) 1988-1989, 1992-1995, 1998, 2001-2002, 2004, 2006, 2009-2011
+   Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Use this to suppress gcc's `...may be used before initialized' warnings. */
+#ifdef lint
+# define IF_LINT(Code) Code
+#else
+# define IF_LINT(Code) /* empty */
+#endif
+
+/* Define `__attribute__' and `volatile' first
+   so that they're used consistently in all system includes.  */
+#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 6) || __STRICT_ANSI__
+# define __attribute__(x)
+#endif
+
+#include <verify.h>
+
+#include <sys/types.h>
+
+#include <sys/stat.h>
+#include "stat-macros.h"
+
+#ifndef STAT_BLOCKSIZE
+# if HAVE_STRUCT_STAT_ST_BLKSIZE
+#  define STAT_BLOCKSIZE(s) ((s).st_blksize)
+# else
+#  define STAT_BLOCKSIZE(s) (8 * 1024)
+# endif
+#endif
+
+#include <unistd.h>
+
+#include <fcntl.h>
+#include <time.h>
+
+#include <sys/wait.h>
+
+#include <dirent.h>
+#ifndef _D_EXACT_NAMLEN
+# define _D_EXACT_NAMLEN(dp) strlen ((dp)->d_name)
+#endif
+
+#include <stdlib.h>
+#define EXIT_TROUBLE 2
+
+#include <limits.h>
+#include <locale.h>
+#include <stddef.h>
+#include <inttypes.h>
+
+#include <string.h>
+#if ! HAVE_STRCASECOLL
+# if HAVE_STRICOLL || defined stricoll
+#  define strcasecoll(a, b) stricoll (a, b)
+# else
+#  define strcasecoll(a, b) strcasecmp (a, b) /* best we can do */
+# endif
+#endif
+#if ! (HAVE_STRCASECMP || defined strcasecmp)
+int strcasecmp (char const *, char const *);
+#endif
+
+#include <gettext.h>
+#if ! ENABLE_NLS
+# undef textdomain
+# define textdomain(Domainname) /* empty */
+# undef bindtextdomain
+# define bindtextdomain(Domainname, Dirname) /* empty */
+#endif
+
+#define _(msgid) gettext (msgid)
+#define N_(msgid) msgid
+
+#include <ctype.h>
+
+/* ISDIGIT differs from isdigit, as follows:
+   - Its arg may be any int or unsigned int; it need not be an unsigned char.
+   - It's guaranteed to evaluate its argument exactly once.
+   - It's typically faster.
+   POSIX 1003.1-2001 says that only '0' through '9' are digits.
+   Prefer ISDIGIT to isdigit unless it's important to use the locale's
+   definition of `digit' even when the host does not conform to POSIX.  */
+#define ISDIGIT(c) ((unsigned int) (c) - '0' <= 9)
+
+#include <errno.h>
+
+#include <signal.h>
+#if !defined SIGCHLD && defined SIGCLD
+# define SIGCHLD SIGCLD
+#endif
+
+#undef MIN
+#undef MAX
+#define MIN(a, b) ((a) <= (b) ? (a) : (b))
+#define MAX(a, b) ((a) >= (b) ? (a) : (b))
+
+#include <stdbool.h>
+#include <intprops.h>
+#include "propername.h"
+#include "version.h"
+
+/* Type used for fast comparison of several bytes at a time.  */
+
+#ifndef word
+# define word uintmax_t
+#endif
+
+/* The integer type of a line number.  Since files are read into main
+   memory, ptrdiff_t should be wide enough.  */
+
+typedef ptrdiff_t lin;
+#define LIN_MAX PTRDIFF_MAX
+verify (TYPE_SIGNED (lin));
+verify (sizeof (ptrdiff_t) <= sizeof (lin));
+verify (sizeof (lin) <= sizeof (long int));
+
+/* This section contains POSIX-compliant defaults for macros
+   that are meant to be overridden by hand in config.h as needed.  */
+
+#ifndef file_name_cmp
+# define file_name_cmp strcmp
+#endif
+
+#ifndef initialize_main
+# define initialize_main(argcp, argvp)
+#endif
+
+#ifndef NULL_DEVICE
+# define NULL_DEVICE "/dev/null"
+#endif
+
+/* Do struct stat *S, *T describe the same special file?  */
+#ifndef same_special_file
+# if HAVE_ST_RDEV && defined S_ISBLK && defined S_ISCHR
+#  define same_special_file(s, t) \
+     (((S_ISBLK ((s)->st_mode) && S_ISBLK ((t)->st_mode)) \
+       || (S_ISCHR ((s)->st_mode) && S_ISCHR ((t)->st_mode))) \
+      && (s)->st_rdev == (t)->st_rdev)
+# else
+#  define same_special_file(s, t) 0
+# endif
+#endif
+
+/* Do struct stat *S, *T describe the same file?  Answer -1 if unknown.  */
+#ifndef same_file
+# define same_file(s, t) \
+    ((((s)->st_ino == (t)->st_ino) && ((s)->st_dev == (t)->st_dev)) \
+     || same_special_file (s, t))
+#endif
+
+/* Do struct stat *S, *T have the same file attributes?
+
+   POSIX says that two files are identical if st_ino and st_dev are
+   the same, but many file systems incorrectly assign the same (device,
+   inode) pair to two distinct files, including:
+
+   - GNU/Linux NFS servers that export all local file systems as a
+     single NFS file system, if a local device number (st_dev) exceeds
+     255, or if a local inode number (st_ino) exceeds 16777215.
+
+   - Network Appliance NFS servers in snapshot directories; see
+     Network Appliance bug #195.
+
+   - ClearCase MVFS; see bug id ATRia04618.
+
+   Check whether two files that purport to be the same have the same
+   attributes, to work around instances of this common bug.  Do not
+   inspect all attributes, only attributes useful in checking for this
+   bug.
+
+   It's possible for two distinct files on a buggy file system to have
+   the same attributes, but it's not worth slowing down all
+   implementations (or complicating the configuration) to cater to
+   these rare cases in buggy implementations.  */
+
+#ifndef same_file_attributes
+# define same_file_attributes(s, t) \
+   ((s)->st_mode == (t)->st_mode \
+    && (s)->st_nlink == (t)->st_nlink \
+    && (s)->st_uid == (t)->st_uid \
+    && (s)->st_gid == (t)->st_gid \
+    && (s)->st_size == (t)->st_size \
+    && (s)->st_mtime == (t)->st_mtime \
+    && (s)->st_ctime == (t)->st_ctime)
+#endif
+
+#define STREQ(a, b) (strcmp (a, b) == 0)
diff --git a/src/util.c b/src/util.c
new file mode 100644
index 0000000..5808434
--- /dev/null
+++ b/src/util.c
@@ -0,0 +1,816 @@
+/* Support routines for GNU DIFF.
+
+   Copyright (C) 1988-1989, 1992-1995, 1998, 2001-2002, 2004, 2006, 2009-2011
+   Free Software Foundation, Inc.
+
+   This file is part of GNU DIFF.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "diff.h"
+#include <dirname.h>
+#include <error.h>
+#include <sh-quote.h>
+#include <xalloc.h>
+
+char const pr_program[] = PR_PROGRAM;
+
+/* Queue up one-line messages to be printed at the end,
+   when -l is specified.  Each message is recorded with a `struct msg'.  */
+
+struct msg
+{
+  struct msg *next;
+  char args[1]; /* Format + 4 args, each '\0' terminated, concatenated.  */
+};
+
+/* Head of the chain of queues messages.  */
+
+static struct msg *msg_chain;
+
+/* Tail of the chain of queues messages.  */
+
+static struct msg **msg_chain_end = &msg_chain;
+
+/* Use when a system call returns non-zero status.
+   NAME should normally be the file name.  */
+
+void
+perror_with_name (char const *name)
+{
+  error (0, errno, "%s", name);
+}
+
+/* Use when a system call returns non-zero status and that is fatal.  */
+
+void
+pfatal_with_name (char const *name)
+{
+  int e = errno;
+  print_message_queue ();
+  error (EXIT_TROUBLE, e, "%s", name);
+  abort ();
+}
+
+/* Print an error message containing MSGID, then exit.  */
+
+void
+fatal (char const *msgid)
+{
+  print_message_queue ();
+  error (EXIT_TROUBLE, 0, "%s", _(msgid));
+  abort ();
+}
+
+/* Like printf, except if -l in effect then save the message and print later.
+   This is used for things like "Only in ...".  */
+
+void
+message (char const *format_msgid, char const *arg1, char const *arg2)
+{
+  message5 (format_msgid, arg1, arg2, 0, 0);
+}
+
+void
+message5 (char const *format_msgid, char const *arg1, char const *arg2,
+	  char const *arg3, char const *arg4)
+{
+  if (paginate)
+    {
+      char *p;
+      char const *arg[5];
+      int i;
+      size_t size[5];
+      size_t total_size = offsetof (struct msg, args);
+      struct msg *new;
+
+      arg[0] = format_msgid;
+      arg[1] = arg1;
+      arg[2] = arg2;
+      arg[3] = arg3 ? arg3 : "";
+      arg[4] = arg4 ? arg4 : "";
+
+      for (i = 0;  i < 5;  i++)
+	total_size += size[i] = strlen (arg[i]) + 1;
+
+      new = xmalloc (total_size);
+
+      for (i = 0, p = new->args;  i < 5;  p += size[i++])
+	memcpy (p, arg[i], size[i]);
+
+      *msg_chain_end = new;
+      new->next = 0;
+      msg_chain_end = &new->next;
+    }
+  else
+    {
+      if (sdiff_merge_assist)
+	putchar (' ');
+      printf (_(format_msgid), arg1, arg2, arg3, arg4);
+    }
+}
+
+/* Output all the messages that were saved up by calls to `message'.  */
+
+void
+print_message_queue (void)
+{
+  char const *arg[5];
+  int i;
+  struct msg *m = msg_chain;
+
+  while (m)
+    {
+      struct msg *next = m->next;
+      arg[0] = m->args;
+      for (i = 0;  i < 4;  i++)
+	arg[i + 1] = arg[i] + strlen (arg[i]) + 1;
+      printf (_(arg[0]), arg[1], arg[2], arg[3], arg[4]);
+      free (m);
+      m = next;
+    }
+}
+
+/* Call before outputting the results of comparing files NAME0 and NAME1
+   to set up OUTFILE, the stdio stream for the output to go to.
+
+   Usually, OUTFILE is just stdout.  But when -l was specified
+   we fork off a `pr' and make OUTFILE a pipe to it.
+   `pr' then outputs to our stdout.  */
+
+static char const *current_name0;
+static char const *current_name1;
+static bool currently_recursive;
+
+void
+setup_output (char const *name0, char const *name1, bool recursive)
+{
+  current_name0 = name0;
+  current_name1 = name1;
+  currently_recursive = recursive;
+  outfile = 0;
+}
+
+#if HAVE_WORKING_FORK
+static pid_t pr_pid;
+#endif
+
+void
+begin_output (void)
+{
+  char *name;
+
+  if (outfile != 0)
+    return;
+
+  /* Construct the header of this piece of diff.  */
+  name = xmalloc (strlen (current_name0) + strlen (current_name1)
+		  + strlen (switch_string) + 7);
+
+  /* POSIX 1003.1-2001 specifies this format.  But there are some bugs in
+     the standard: it says that we must print only the last component
+     of the pathnames, and it requires two spaces after "diff" if
+     there are no options.  These requirements are silly and do not
+     match historical practice.  */
+  sprintf (name, "diff%s %s %s", switch_string, current_name0, current_name1);
+
+  if (paginate)
+    {
+      if (fflush (stdout) != 0)
+	pfatal_with_name (_("write failed"));
+
+      /* Make OUTFILE a pipe to a subsidiary `pr'.  */
+      {
+#if HAVE_WORKING_FORK
+	int pipes[2];
+
+	if (pipe (pipes) != 0)
+	  pfatal_with_name ("pipe");
+
+	pr_pid = fork ();
+	if (pr_pid < 0)
+	  pfatal_with_name ("fork");
+
+	if (pr_pid == 0)
+	  {
+	    close (pipes[1]);
+	    if (pipes[0] != STDIN_FILENO)
+	      {
+		if (dup2 (pipes[0], STDIN_FILENO) < 0)
+		  pfatal_with_name ("dup2");
+		close (pipes[0]);
+	      }
+
+	    execl (pr_program, pr_program, "-h", name, (char *) 0);
+	    _exit (errno == ENOENT ? 127 : 126);
+	  }
+	else
+	  {
+	    close (pipes[0]);
+	    outfile = fdopen (pipes[1], "w");
+	    if (!outfile)
+	      pfatal_with_name ("fdopen");
+	  }
+#else
+	char *command = xmalloc (sizeof pr_program - 1 + 7
+				 + shell_quote_length (name) + 1);
+	char *p;
+	sprintf (command, "%s -f -h ", pr_program);
+	p = command + sizeof pr_program - 1 + 7;
+	p = shell_quote_copy (p, name);
+	*p = 0;
+	errno = 0;
+	outfile = popen (command, "w");
+	if (!outfile)
+	  pfatal_with_name (command);
+	free (command);
+#endif
+      }
+    }
+  else
+    {
+
+      /* If -l was not specified, output the diff straight to `stdout'.  */
+
+      outfile = stdout;
+
+      /* If handling multiple files (because scanning a directory),
+	 print which files the following output is about.  */
+      if (currently_recursive)
+	printf ("%s\n", name);
+    }
+
+  free (name);
+
+  /* A special header is needed at the beginning of context output.  */
+  switch (output_style)
+    {
+    case OUTPUT_CONTEXT:
+      print_context_header (files, false);
+      break;
+
+    case OUTPUT_UNIFIED:
+      print_context_header (files, true);
+      break;
+
+    default:
+      break;
+    }
+}
+
+/* Call after the end of output of diffs for one file.
+   Close OUTFILE and get rid of the `pr' subfork.  */
+
+void
+finish_output (void)
+{
+  if (outfile != 0 && outfile != stdout)
+    {
+      int status;
+      int wstatus;
+      int werrno = 0;
+      if (ferror (outfile))
+	fatal ("write failed");
+#if ! HAVE_WORKING_FORK
+      wstatus = pclose (outfile);
+      if (wstatus == -1)
+	werrno = errno;
+#else
+      if (fclose (outfile) != 0)
+	pfatal_with_name (_("write failed"));
+      if (waitpid (pr_pid, &wstatus, 0) < 0)
+	pfatal_with_name ("waitpid");
+#endif
+      status = (! werrno && WIFEXITED (wstatus)
+		? WEXITSTATUS (wstatus)
+		: INT_MAX);
+      if (status)
+	error (EXIT_TROUBLE, werrno,
+	       _(status == 126
+		 ? "subsidiary program `%s' could not be invoked"
+		 : status == 127
+		 ? "subsidiary program `%s' not found"
+		 : status == INT_MAX
+		 ? "subsidiary program `%s' failed"
+		 : "subsidiary program `%s' failed (exit status %d)"),
+	       pr_program, status);
+    }
+
+  outfile = 0;
+}
+
+/* Compare two lines (typically one from each input file)
+   according to the command line options.
+   For efficiency, this is invoked only when the lines do not match exactly
+   but an option like -i might cause us to ignore the difference.
+   Return nonzero if the lines differ.  */
+
+bool
+lines_differ (char const *s1, char const *s2)
+{
+  register char const *t1 = s1;
+  register char const *t2 = s2;
+  size_t column = 0;
+
+  while (1)
+    {
+      register unsigned char c1 = *t1++;
+      register unsigned char c2 = *t2++;
+
+      /* Test for exact char equality first, since it's a common case.  */
+      if (c1 != c2)
+	{
+	  switch (ignore_white_space)
+	    {
+	    case IGNORE_ALL_SPACE:
+	      /* For -w, just skip past any white space.  */
+	      while (isspace (c1) && c1 != '\n') c1 = *t1++;
+	      while (isspace (c2) && c2 != '\n') c2 = *t2++;
+	      break;
+
+	    case IGNORE_SPACE_CHANGE:
+	      /* For -b, advance past any sequence of white space in
+		 line 1 and consider it just one space, or nothing at
+		 all if it is at the end of the line.  */
+	      if (isspace (c1))
+		{
+		  while (c1 != '\n')
+		    {
+		      c1 = *t1++;
+		      if (! isspace (c1))
+			{
+			  --t1;
+			  c1 = ' ';
+			  break;
+			}
+		    }
+		}
+
+	      /* Likewise for line 2.  */
+	      if (isspace (c2))
+		{
+		  while (c2 != '\n')
+		    {
+		      c2 = *t2++;
+		      if (! isspace (c2))
+			{
+			  --t2;
+			  c2 = ' ';
+			  break;
+			}
+		    }
+		}
+
+	      if (c1 != c2)
+		{
+		  /* If we went too far when doing the simple test
+		     for equality, go back to the first non-white-space
+		     character in both sides and try again.  */
+		  if (c2 == ' ' && c1 != '\n'
+		      && s1 + 1 < t1
+		      && isspace ((unsigned char) t1[-2]))
+		    {
+		      --t1;
+		      continue;
+		    }
+		  if (c1 == ' ' && c2 != '\n'
+		      && s2 + 1 < t2
+		      && isspace ((unsigned char) t2[-2]))
+		    {
+		      --t2;
+		      continue;
+		    }
+		}
+
+	      break;
+
+	    case IGNORE_TRAILING_SPACE:
+	    case IGNORE_TAB_EXPANSION_AND_TRAILING_SPACE:
+	      if (isspace (c1) && isspace (c2))
+		{
+		  unsigned char c;
+		  if (c1 != '\n')
+		    {
+		      char const *p = t1;
+		      while ((c = *p) != '\n' && isspace (c))
+			++p;
+		      if (c != '\n')
+			break;
+		    }
+		  if (c2 != '\n')
+		    {
+		      char const *p = t2;
+		      while ((c = *p) != '\n' && isspace (c))
+			++p;
+		      if (c != '\n')
+			break;
+		    }
+		  /* Both lines have nothing but whitespace left.  */
+		  return false;
+		}
+	      if (ignore_white_space == IGNORE_TRAILING_SPACE)
+		break;
+	      /* Fall through.  */
+	    case IGNORE_TAB_EXPANSION:
+	      if ((c1 == ' ' && c2 == '\t')
+		  || (c1 == '\t' && c2 == ' '))
+		{
+		  size_t column2 = column;
+		  for (;; c1 = *t1++)
+		    {
+		      if (c1 == ' ')
+			column++;
+		      else if (c1 == '\t')
+			column += tabsize - column % tabsize;
+		      else
+			break;
+		    }
+		  for (;; c2 = *t2++)
+		    {
+		      if (c2 == ' ')
+			column2++;
+		      else if (c2 == '\t')
+			column2 += tabsize - column2 % tabsize;
+		      else
+			break;
+		    }
+		  if (column != column2)
+		    return true;
+		}
+	      break;
+
+	    case IGNORE_NO_WHITE_SPACE:
+	      break;
+	    }
+
+	  /* Lowercase all letters if -i is specified.  */
+
+	  if (ignore_case)
+	    {
+	      c1 = tolower (c1);
+	      c2 = tolower (c2);
+	    }
+
+	  if (c1 != c2)
+	    break;
+	}
+      if (c1 == '\n')
+	return false;
+
+      column += c1 == '\t' ? tabsize - column % tabsize : 1;
+    }
+
+  return true;
+}
+
+/* Find the consecutive changes at the start of the script START.
+   Return the last link before the first gap.  */
+
+struct change *
+find_change (struct change *start)
+{
+  return start;
+}
+
+struct change *
+find_reverse_change (struct change *start)
+{
+  return start;
+}
+
+/* Divide SCRIPT into pieces by calling HUNKFUN and
+   print each piece with PRINTFUN.
+   Both functions take one arg, an edit script.
+
+   HUNKFUN is called with the tail of the script
+   and returns the last link that belongs together with the start
+   of the tail.
+
+   PRINTFUN takes a subscript which belongs together (with a null
+   link at the end) and prints it.  */
+
+void
+print_script (struct change *script,
+	      struct change * (*hunkfun) (struct change *),
+	      void (*printfun) (struct change *))
+{
+  struct change *next = script;
+
+  while (next)
+    {
+      struct change *this, *end;
+
+      /* Find a set of changes that belong together.  */
+      this = next;
+      end = (*hunkfun) (next);
+
+      /* Disconnect them from the rest of the changes,
+	 making them a hunk, and remember the rest for next iteration.  */
+      next = end->link;
+      end->link = 0;
+#ifdef DEBUG
+      debug_script (this);
+#endif
+
+      /* Print this hunk.  */
+      (*printfun) (this);
+
+      /* Reconnect the script so it will all be freed properly.  */
+      end->link = next;
+    }
+}
+
+/* Print the text of a single line LINE,
+   flagging it with the characters in LINE_FLAG (which say whether
+   the line is inserted, deleted, changed, etc.).  LINE_FLAG must not
+   end in a blank, unless it is a single blank.  */
+
+void
+print_1_line (char const *line_flag, char const *const *line)
+{
+  char const *base = line[0], *limit = line[1]; /* Help the compiler.  */
+  FILE *out = outfile; /* Help the compiler some more.  */
+  char const *flag_format = 0;
+
+  /* If -T was specified, use a Tab between the line-flag and the text.
+     Otherwise use a Space (as Unix diff does).
+     Print neither space nor tab if line-flags are empty.
+     But omit trailing blanks if requested.  */
+
+  if (line_flag && *line_flag)
+    {
+      char const *flag_format_1 = flag_format = initial_tab ? "%s\t" : "%s ";
+      char const *line_flag_1 = line_flag;
+
+      if (suppress_blank_empty && **line == '\n')
+	{
+	  flag_format_1 = "%s";
+
+	  /* This hack to omit trailing blanks takes advantage of the
+	     fact that the only way that LINE_FLAG can end in a blank
+	     is when LINE_FLAG consists of a single blank.  */
+	  line_flag_1 += *line_flag_1 == ' ';
+	}
+
+      fprintf (out, flag_format_1, line_flag_1);
+    }
+
+  output_1_line (base, limit, flag_format, line_flag);
+
+  if ((!line_flag || line_flag[0]) && limit[-1] != '\n')
+    fprintf (out, "\n\\ %s\n", _("No newline at end of file"));
+}
+
+/* Output a line from BASE up to LIMIT.
+   With -t, expand white space characters to spaces, and if FLAG_FORMAT
+   is nonzero, output it with argument LINE_FLAG after every
+   internal carriage return, so that tab stops continue to line up.  */
+
+void
+output_1_line (char const *base, char const *limit, char const *flag_format,
+	       char const *line_flag)
+{
+  if (!expand_tabs)
+    fwrite (base, sizeof (char), limit - base, outfile);
+  else
+    {
+      register FILE *out = outfile;
+      register unsigned char c;
+      register char const *t = base;
+      register size_t column = 0;
+      size_t tab_size = tabsize;
+
+      while (t < limit)
+	switch ((c = *t++))
+	  {
+	  case '\t':
+	    {
+	      size_t spaces = tab_size - column % tab_size;
+	      column += spaces;
+	      do
+		putc (' ', out);
+	      while (--spaces);
+	    }
+	    break;
+
+	  case '\r':
+	    putc (c, out);
+	    if (flag_format && t < limit && *t != '\n')
+	      fprintf (out, flag_format, line_flag);
+	    column = 0;
+	    break;
+
+	  case '\b':
+	    if (column == 0)
+	      continue;
+	    column--;
+	    putc (c, out);
+	    break;
+
+	  default:
+	    column += isprint (c) != 0;
+	    putc (c, out);
+	    break;
+	  }
+    }
+}
+
+char const change_letter[] = { 0, 'd', 'a', 'c' };
+
+/* Translate an internal line number (an index into diff's table of lines)
+   into an actual line number in the input file.
+   The internal line number is I.  FILE points to the data on the file.
+
+   Internal line numbers count from 0 starting after the prefix.
+   Actual line numbers count from 1 within the entire file.  */
+
+lin
+translate_line_number (struct file_data const *file, lin i)
+{
+  return i + file->prefix_lines + 1;
+}
+
+/* Translate a line number range.  This is always done for printing,
+   so for convenience translate to long int rather than lin, so that the
+   caller can use printf with "%ld" without casting.  */
+
+void
+translate_range (struct file_data const *file,
+		 lin a, lin b,
+		 long int *aptr, long int *bptr)
+{
+  *aptr = translate_line_number (file, a - 1) + 1;
+  *bptr = translate_line_number (file, b + 1) - 1;
+}
+
+/* Print a pair of line numbers with SEPCHAR, translated for file FILE.
+   If the two numbers are identical, print just one number.
+
+   Args A and B are internal line numbers.
+   We print the translated (real) line numbers.  */
+
+void
+print_number_range (char sepchar, struct file_data *file, lin a, lin b)
+{
+  long int trans_a, trans_b;
+  translate_range (file, a, b, &trans_a, &trans_b);
+
+  /* Note: we can have B < A in the case of a range of no lines.
+     In this case, we should print the line number before the range,
+     which is B.  */
+  if (trans_b > trans_a)
+    fprintf (outfile, "%ld%c%ld", trans_a, sepchar, trans_b);
+  else
+    fprintf (outfile, "%ld", trans_b);
+}
+
+/* Look at a hunk of edit script and report the range of lines in each file
+   that it applies to.  HUNK is the start of the hunk, which is a chain
+   of `struct change'.  The first and last line numbers of file 0 are stored in
+   *FIRST0 and *LAST0, and likewise for file 1 in *FIRST1 and *LAST1.
+   Note that these are internal line numbers that count from 0.
+
+   If no lines from file 0 are deleted, then FIRST0 is LAST0+1.
+
+   Return UNCHANGED if only ignorable lines are inserted or deleted,
+   OLD if lines of file 0 are deleted,
+   NEW if lines of file 1 are inserted,
+   and CHANGED if both kinds of changes are found. */
+
+enum changes
+analyze_hunk (struct change *hunk,
+	      lin *first0, lin *last0,
+	      lin *first1, lin *last1)
+{
+  struct change *next;
+  lin l0, l1;
+  lin show_from, show_to;
+  lin i;
+  bool trivial = ignore_blank_lines || ignore_regexp.fastmap;
+  size_t trivial_length = ignore_blank_lines - 1;
+    /* If 0, ignore zero-length lines;
+       if SIZE_MAX, do not ignore lines just because of their length.  */
+
+  bool skip_white_space =
+    ignore_blank_lines && IGNORE_TRAILING_SPACE <= ignore_white_space;
+  bool skip_leading_white_space =
+    skip_white_space && IGNORE_SPACE_CHANGE <= ignore_white_space;
+
+  char const * const *linbuf0 = files[0].linbuf;  /* Help the compiler.  */
+  char const * const *linbuf1 = files[1].linbuf;
+
+  show_from = show_to = 0;
+
+  *first0 = hunk->line0;
+  *first1 = hunk->line1;
+
+  next = hunk;
+  do
+    {
+      l0 = next->line0 + next->deleted - 1;
+      l1 = next->line1 + next->inserted - 1;
+      show_from += next->deleted;
+      show_to += next->inserted;
+
+      for (i = next->line0; i <= l0 && trivial; i++)
+	{
+	  char const *line = linbuf0[i];
+	  char const *newline = linbuf0[i + 1] - 1;
+	  size_t len = newline - line;
+	  char const *p = line;
+	  if (skip_white_space)
+	    for (; *p != '\n'; p++)
+	      if (! isspace ((unsigned char) *p))
+		{
+		  if (! skip_leading_white_space)
+		    p = line;
+		  break;
+		}
+	  if (newline - p != trivial_length
+	      && (! ignore_regexp.fastmap
+		  || re_search (&ignore_regexp, line, len, 0, len, 0) < 0))
+	    trivial = 0;
+	}
+
+      for (i = next->line1; i <= l1 && trivial; i++)
+	{
+	  char const *line = linbuf1[i];
+	  char const *newline = linbuf1[i + 1] - 1;
+	  size_t len = newline - line;
+	  char const *p = line;
+	  if (skip_white_space)
+	    for (; *p != '\n'; p++)
+	      if (! isspace ((unsigned char) *p))
+		{
+		  if (! skip_leading_white_space)
+		    p = line;
+		  break;
+		}
+	  if (newline - p != trivial_length
+	      && (! ignore_regexp.fastmap
+		  || re_search (&ignore_regexp, line, len, 0, len, 0) < 0))
+	    trivial = 0;
+	}
+    }
+  while ((next = next->link) != 0);
+
+  *last0 = l0;
+  *last1 = l1;
+
+  /* If all inserted or deleted lines are ignorable,
+     tell the caller to ignore this hunk.  */
+
+  if (trivial)
+    return UNCHANGED;
+
+  return (show_from ? OLD : UNCHANGED) | (show_to ? NEW : UNCHANGED);
+}
+
+/* Concatenate three strings, returning a newly malloc'd string.  */
+
+char *
+concat (char const *s1, char const *s2, char const *s3)
+{
+  char *new = xmalloc (strlen (s1) + strlen (s2) + strlen (s3) + 1);
+  sprintf (new, "%s%s%s", s1, s2, s3);
+  return new;
+}
+
+/* Yield a new block of SIZE bytes, initialized to zero.  */
+
+void *
+zalloc (size_t size)
+{
+  void *p = xmalloc (size);
+  memset (p, 0, size);
+  return p;
+}
+
+void
+debug_script (struct change *sp)
+{
+  fflush (stdout);
+
+  for (; sp; sp = sp->link)
+    {
+      long int line0 = sp->line0;
+      long int line1 = sp->line1;
+      long int deleted = sp->deleted;
+      long int inserted = sp->inserted;
+      fprintf (stderr, "%3ld %3ld delete %ld insert %ld\n",
+	       line0, line1, deleted, inserted);
+    }
+
+  fflush (stderr);
+}