2 dnl Run a program to determine whether link(2) follows symlinks.
3 dnl Set LINK_FOLLOWS_SYMLINKS accordingly.
5 # Copyright (C) 1999-2001, 2004-2006, 2009 Free Software Foundation, Inc.
6 # This file is free software; the Free Software Foundation
7 # gives unlimited permission to copy and/or distribute it,
8 # with or without modifications, as long as this notice is preserved.
10 AC_DEFUN([gl_AC_FUNC_LINK_FOLLOWS_SYMLINK],
12 AC_CACHE_CHECK([whether link(2) dereferences a symlink],
13 gl_ac_cv_func_link_follows_symlink,
15 # Create a regular file.
17 AC_RUN_IFELSE([AC_LANG_SOURCE([[
18 # include <sys/types.h>
19 # include <sys/stat.h>
23 # define SAME_INODE(Stat_buf_1, Stat_buf_2) \
24 ((Stat_buf_1).st_ino == (Stat_buf_2).st_ino \
25 && (Stat_buf_1).st_dev == (Stat_buf_2).st_dev)
30 const char *file = "conftest.file";
31 const char *sym = "conftest.sym";
32 const char *hard = "conftest.hard";
33 struct stat sb_file, sb_hard;
35 /* Create a symlink to the regular file. */
36 if (symlink (file, sym))
39 /* Create a hard link to that symlink. */
43 if (lstat (hard, &sb_hard))
45 if (lstat (file, &sb_file))
48 /* If the dev/inode of hard and file are the same, then
49 the link call followed the symlink. */
50 return SAME_INODE (sb_hard, sb_file) ? 0 : 1;
53 [gl_ac_cv_func_link_follows_symlink=yes],
54 [gl_ac_cv_func_link_follows_symlink=no],
55 [gl_ac_cv_func_link_follows_symlink=yes] dnl We're cross compiling.
58 if test $gl_ac_cv_func_link_follows_symlink = yes; then
59 AC_DEFINE([LINK_FOLLOWS_SYMLINKS], [1],
60 [Define if `link(2)' dereferences symbolic links.])