diff options
Diffstat (limited to 'm4/getcwd-path-max.m4')
| -rw-r--r-- | m4/getcwd-path-max.m4 | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/m4/getcwd-path-max.m4 b/m4/getcwd-path-max.m4 new file mode 100644 index 0000000..5e6d58b --- /dev/null +++ b/m4/getcwd-path-max.m4 @@ -0,0 +1,190 @@ +#serial 13 +# Check for several getcwd bugs with long file names. +# If so, arrange to compile the wrapper function. + +# This is necessary for at least GNU libc on linux-2.4.19 and 2.4.20. +# I've heard that this is due to a Linux kernel bug, and that it has +# been fixed between 2.4.21-pre3 and 2.4.21-pre4. */ + +# Copyright (C) 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc. +# This file 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. + +# From Jim Meyering + +AC_DEFUN([gl_FUNC_GETCWD_PATH_MAX], +[ + AC_CHECK_DECLS_ONCE(getcwd) + AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) + AC_CACHE_CHECK([whether getcwd handles long file names properly], + gl_cv_func_getcwd_path_max, + [# Arrange for deletion of the temporary directory this test creates. + ac_clean_files="$ac_clean_files confdir3" + AC_RUN_IFELSE( + [AC_LANG_SOURCE( + [[ +#include <errno.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <limits.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <fcntl.h> + +#ifndef AT_FDCWD +# define AT_FDCWD 0 +#endif +#ifdef ENAMETOOLONG +# define is_ENAMETOOLONG(x) ((x) == ENAMETOOLONG) +#else +# define is_ENAMETOOLONG(x) 0 +#endif + +/* Don't get link errors because mkdir is redefined to rpl_mkdir. */ +#undef mkdir + +#ifndef S_IRWXU +# define S_IRWXU 0700 +#endif + +/* The length of this name must be 8. */ +#define DIR_NAME "confdir3" +#define DIR_NAME_LEN 8 +#define DIR_NAME_SIZE (DIR_NAME_LEN + 1) + +/* The length of "../". */ +#define DOTDOTSLASH_LEN 3 + +/* Leftover bytes in the buffer, to work around library or OS bugs. */ +#define BUF_SLOP 20 + +int +main () +{ +#ifndef PATH_MAX + /* The Hurd doesn't define this, so getcwd can't exhibit the bug -- + at least not on a local file system. And if we were to start worrying + about remote file systems, we'd have to enable the wrapper function + all of the time, just to be safe. That's not worth the cost. */ + exit (0); +#elif ((INT_MAX / (DIR_NAME_SIZE / DOTDOTSLASH_LEN + 1) \ + - DIR_NAME_SIZE - BUF_SLOP) \ + <= PATH_MAX) + /* FIXME: Assuming there's a system for which this is true, + this should be done in a compile test. */ + exit (0); +#else + char buf[PATH_MAX * (DIR_NAME_SIZE / DOTDOTSLASH_LEN + 1) + + DIR_NAME_SIZE + BUF_SLOP]; + char *cwd = getcwd (buf, PATH_MAX); + size_t initial_cwd_len; + size_t cwd_len; + int fail = 0; + size_t n_chdirs = 0; + + if (cwd == NULL) + exit (1); + + cwd_len = initial_cwd_len = strlen (cwd); + + while (1) + { + size_t dotdot_max = PATH_MAX * (DIR_NAME_SIZE / DOTDOTSLASH_LEN); + char *c = NULL; + + cwd_len += DIR_NAME_SIZE; + /* If mkdir or chdir fails, it could be that this system cannot create + any file with an absolute name longer than PATH_MAX, such as cygwin. + If so, leave fail as 0, because the current working directory can't + be too long for getcwd if it can't even be created. For other + errors, be pessimistic and consider that as a failure, too. */ + if (mkdir (DIR_NAME, S_IRWXU) < 0 || chdir (DIR_NAME) < 0) + { + if (! (errno == ERANGE || is_ENAMETOOLONG (errno))) + fail = 2; + break; + } + + if (PATH_MAX <= cwd_len && cwd_len < PATH_MAX + DIR_NAME_SIZE) + { + c = getcwd (buf, PATH_MAX); + if (!c && errno == ENOENT) + { + fail = 1; + break; + } + if (c || ! (errno == ERANGE || is_ENAMETOOLONG (errno))) + { + fail = 2; + break; + } + } + + if (dotdot_max <= cwd_len - initial_cwd_len) + { + if (dotdot_max + DIR_NAME_SIZE < cwd_len - initial_cwd_len) + break; + c = getcwd (buf, cwd_len + 1); + if (!c) + { + if (! (errno == ERANGE || errno == ENOENT + || is_ENAMETOOLONG (errno))) + { + fail = 2; + break; + } + if (AT_FDCWD || errno == ERANGE || errno == ENOENT) + { + fail = 1; + break; + } + } + } + + if (c && strlen (c) != cwd_len) + { + fail = 2; + break; + } + ++n_chdirs; + } + + /* Leaving behind such a deep directory is not polite. + So clean up here, right away, even though the driving + shell script would also clean up. */ + { + size_t i; + + /* Try rmdir first, in case the chdir failed. */ + rmdir (DIR_NAME); + for (i = 0; i <= n_chdirs; i++) + { + if (chdir ("..") < 0) + break; + if (rmdir (DIR_NAME) != 0) + break; + } + } + + exit (fail); +#endif +} + ]])], + [gl_cv_func_getcwd_path_max=yes], + [case $? in + 1) gl_cv_func_getcwd_path_max='no, but it is partly working';; + *) gl_cv_func_getcwd_path_max=no;; + esac], + [gl_cv_func_getcwd_path_max=no]) + ]) + case $gl_cv_func_getcwd_path_max in + no,*) + AC_DEFINE([HAVE_PARTLY_WORKING_GETCWD], 1, + [Define to 1 if getcwd works, except it sometimes fails when it shouldn't, + setting errno to ERANGE, ENAMETOOLONG, or ENOENT. If __GETCWD_PREFIX + is not defined, it doesn't matter whether HAVE_PARTLY_WORKING_GETCWD + is defined.]);; + esac +]) |