diff options
Diffstat (limited to 'm4/memchr.m4')
| -rw-r--r-- | m4/memchr.m4 | 74 |
1 files changed, 34 insertions, 40 deletions
diff --git a/m4/memchr.m4 b/m4/memchr.m4 index 0be394d..888d2b2 100644 --- a/m4/memchr.m4 +++ b/m4/memchr.m4 @@ -1,5 +1,5 @@ -# memchr.m4 serial 14 -dnl Copyright (C) 2002-2004, 2009-2019 Free Software Foundation, Inc. +# memchr.m4 serial 17 +dnl Copyright (C) 2002-2004, 2009-2020 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. @@ -14,26 +14,17 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR], AC_CHECK_FUNCS_ONCE([mprotect]) AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) - m4_ifdef([gl_FUNC_MEMCHR_OBSOLETE], [ - dnl These days, we assume memchr is present. But if support for old - dnl platforms is desired: - AC_CHECK_FUNCS_ONCE([memchr]) - if test $ac_cv_func_memchr = no; then - HAVE_MEMCHR=0 - fi - ]) - if test $HAVE_MEMCHR = 1; then - # Detect platform-specific bugs in some versions of glibc: - # memchr should not dereference anything with length 0 - # https://bugzilla.redhat.com/show_bug.cgi?id=499689 - # memchr should not dereference overestimated length after a match - # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737 - # https://sourceware.org/bugzilla/show_bug.cgi?id=10162 - # memchr should cast the second argument to 'unsigned char'. - # This bug exists in Android 4.3. - # Assume that memchr works on platforms that lack mprotect. - AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works], - [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ + # Detect platform-specific bugs in some versions of glibc: + # memchr should not dereference anything with length 0 + # https://bugzilla.redhat.com/show_bug.cgi?id=499689 + # memchr should not dereference overestimated length after a match + # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737 + # https://sourceware.org/bugzilla/show_bug.cgi?id=10162 + # memchr should cast the second argument to 'unsigned char'. + # This bug exists in Android 4.3. + # Assume that memchr works on platforms that lack mprotect. + AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works], + [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ #include <string.h> #if HAVE_SYS_MMAN_H # include <fcntl.h> @@ -68,6 +59,7 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR], #endif if (fence) { + /* Test against bugs on glibc systems. */ if (memchr (fence, 0, 0)) result |= 1; strcpy (fence - 9, "12345678"); @@ -75,6 +67,9 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR], result |= 2; if (memchr (fence - 1, 0, 3) != fence - 1) result |= 4; + /* Test against bug on AIX 7.2. */ + if (memchr (fence - 4, '6', 16) != fence - 4) + result |= 8; } /* Test against bug on Android 4.3. */ { @@ -83,27 +78,26 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR], input[1] = 'b'; input[2] = 'c'; if (memchr (input, 0x789abc00 | 'b', 3) != input + 1) - result |= 8; + result |= 16; } return result; ]])], - [gl_cv_func_memchr_works=yes], - [gl_cv_func_memchr_works=no], - [case "$host_os" in - # Guess no on Android. - linux*-android*) gl_cv_func_memchr_works="guessing no" ;; - # Guess yes on native Windows. - mingw*) gl_cv_func_memchr_works="guessing yes" ;; - # Be pessimistic for now. - *) gl_cv_func_memchr_works="guessing no" ;; - esac - ]) - ]) - case "$gl_cv_func_memchr_works" in - *yes) ;; - *) REPLACE_MEMCHR=1 ;; - esac - fi + [gl_cv_func_memchr_works=yes], + [gl_cv_func_memchr_works=no], + [case "$host_os" in + # Guess no on Android. + linux*-android*) gl_cv_func_memchr_works="guessing no" ;; + # Guess yes on native Windows. + mingw*) gl_cv_func_memchr_works="guessing yes" ;; + # If we don't know, obey --enable-cross-guesses. + *) gl_cv_func_memchr_works="$gl_cross_guess_normal" ;; + esac + ]) + ]) + case "$gl_cv_func_memchr_works" in + *yes) ;; + *) REPLACE_MEMCHR=1 ;; + esac ]) # Prerequisites of lib/memchr.c. |