--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/dirname.c	Tue Dec 22 05:31:23 2009 +0000
@@ -0,0 +1,84 @@
+/* dirname.c -- return all but the last element in a file name
+
+   Copyright (C) 1990, 1998, 2000, 2001, 2003, 2004, 2005, 2006 Free Software
+   Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "dirname.h"
+
+#include <string.h>
+#include "xalloc.h"
+
+/* Return the length of the prefix of FILE that will be used by
+   dir_name.  If FILE is in the working directory, this returns zero
+   even though `dir_name (FILE)' will return ".".  Works properly even
+   if there are trailing slashes (by effectively ignoring them).  */
+
+size_t
+dir_len (char const *file)
+{
+  size_t prefix_length = FILE_SYSTEM_PREFIX_LEN (file);
+  size_t length;
+
+  /* Advance prefix_length beyond important leading slashes.  */
+  prefix_length += (prefix_length != 0
+		    ? (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE
+		       && ISSLASH (file[prefix_length]))
+		    : (ISSLASH (file[0])
+		       ? ((DOUBLE_SLASH_IS_DISTINCT_ROOT
+			   && ISSLASH (file[1]) && ! ISSLASH (file[2])
+			   ? 2 : 1))
+		       : 0));
+
+  /* Strip the basename and any redundant slashes before it.  */
+  for (length = last_component (file) - file;
+       prefix_length < length; length--)
+    if (! ISSLASH (file[length - 1]))
+      break;
+  return length;
+}
+
+
+/* In general, we can't use the builtin `dirname' function if available,
+   since it has different meanings in different environments.
+   In some environments the builtin `dirname' modifies its argument.
+
+   Return the leading directories part of FILE, allocated with xmalloc.
+   Works properly even if there are trailing slashes (by effectively
+   ignoring them).  Unlike POSIX dirname(), FILE cannot be NULL.
+
+   If lstat (FILE) would succeed, then { chdir (dir_name (FILE));
+   lstat (base_name (FILE)); } will access the same file.  Likewise,
+   if the sequence { chdir (dir_name (FILE));
+   rename (base_name (FILE), "foo"); } succeeds, you have renamed FILE
+   to "foo" in the same directory FILE was in.  */
+
+char *
+dir_name (char const *file)
+{
+  size_t length = dir_len (file);
+  bool append_dot = (length == 0
+		     || (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE
+			 && length == FILE_SYSTEM_PREFIX_LEN (file)
+			 && file[2] != '\0' && ! ISSLASH (file[2])));
+  char *dir = xmalloc (length + append_dot + 1);
+  memcpy (dir, file, length);
+  if (append_dot)
+    dir[length++] = '.';
+  dir[length] = '\0';
+  return dir;
+}