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(jm_AC_FUNC_LINK_FOLLOWS_SYMLINK): New file/macro.

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Jim Meyering 1999-11-06 21:30:16 +00:00
parent 81718d1a58
commit e2c0a043f7
1 changed files with 55 additions and 0 deletions
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55
m4/link-follow.m4 Normal file
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#serial 1
dnl Run a program to determine whether whether link(2) follows symlinks.
dnl Set LINK_FOLLOWS_SYMLINKS accordingly.
AC_DEFUN(jm_AC_FUNC_LINK_FOLLOWS_SYMLINK,
[dnl
AC_CACHE_CHECK([whether link(2) follows symlinks],
jm_ac_cv_func_link_follows_symlink,
[
# Create a regular file, `conftest.file'.
echo > conftest.file
AC_TRY_RUN(
[
# include <sys/types.h>
# include <sys/stat.h>
# ifdef HAVE_UNISTD_H
# include <unistd.h>
# endif
# define SAME_INODE(Stat_buf_1, Stat_buf_2) \
((Stat_buf_1).st_ino == (Stat_buf_2).st_ino \
&& (Stat_buf_1).st_dev == (Stat_buf_2).st_dev)
int
main ()
{
const char *file = "conftest.file";
const char *sym = "conftest.sym";
const char *hard = "conftest.hard";
struct stat sb_file, sb_hard;
/* Create a symlink `conftest.sym' to it. */
if (symlink (file, sym))
abort ();
/* Create a hard link `conftest.hard' to that symlink. */
if (link (sym, hard))
abort ();
if (lstat (hard, &sb_hard))
abort ();
if (lstat (file, &sb_file))
abort ();
/* If the dev/inode of hard and file are the same, then
the link call followed the symlink. */
return SAME_INODE (sb_hard, sb_file) ? 0 : 1;
}
],
jm_ac_cv_func_link_follows_symlink=yes,
jm_ac_cv_func_link_follows_symlink=no,
jm_ac_cv_func_link_follows_symlink=yes, We're cross compiling.
)
])
])