1 files changed, 64 insertions, 0 deletions
diff --git a/m4/link-follow.m4 b/m4/link-follow.m4
new file mode 100644
index 0000000..69a7018
--- /dev/null
+++ b/m4/link-follow.m4
@@ -0,0 +1,64 @@
+#serial 9
+dnl Run a program to determine whether link(2) follows symlinks.
+dnl Set LINK_FOLLOWS_SYMLINKS accordingly.
+
+# Copyright (C) 1999, 2000, 2001, 2004, 2005, 2006 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.
+
+AC_DEFUN([gl_AC_FUNC_LINK_FOLLOWS_SYMLINK],
+[dnl
+  AC_CACHE_CHECK(
+    [whether link(2) dereferences a symlink specified with a trailing slash],
+		 jm_ac_cv_func_link_follows_symlink,
+  [
+    # Create a regular file.
+    echo > conftest.file
+    AC_TRY_RUN(
+      [
+#       include <sys/types.h>
+#       include <sys/stat.h>
+#       include <unistd.h>
+#       include <stdlib.h>
+
+#       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 to the regular file. */
+	  if (symlink (file, sym))
+	    abort ();
+
+	  /* Create a hard link 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 dnl We're cross compiling.
+    )
+  ])
+  if test $jm_ac_cv_func_link_follows_symlink = yes; then
+    AC_DEFINE(LINK_FOLLOWS_SYMLINKS, 1,
+      [Define if `link(2)' dereferences symbolic links.])
+  fi
+])