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authorJim Meyering <jim@meyering.net>1999-11-06 21:30:16 +0000
committerJim Meyering <jim@meyering.net>1999-11-06 21:30:16 +0000
commite2c0a043f79952b9fff975f1920659d3aa77a00b (patch)
treef261e6d8c24767e7ee8653531a70d5505a92402a /m4
parent81718d1a58062a8908d602f27cee47b96073a8e8 (diff)
downloadcoreutils-e2c0a043f79952b9fff975f1920659d3aa77a00b.tar.xz
(jm_AC_FUNC_LINK_FOLLOWS_SYMLINK): New file/macro.
Diffstat (limited to 'm4')
-rw-r--r--m4/link-follow.m455
1 files changed, 55 insertions, 0 deletions
diff --git a/m4/link-follow.m4 b/m4/link-follow.m4
new file mode 100644
index 000000000..a57ab88a6
--- /dev/null
+++ b/m4/link-follow.m4
@@ -0,0 +1,55 @@
+#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.
+ )
+ ])
+])