--- a/lib/basename.c
+++ b/lib/basename.c
@@ -1,38 +1,32 @@
-/* basename.c -- return the last element in a path
-   Copyright (C) 1990 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 2, or (at your option)
-   any later version.
+/* basename.c -- return the last element in a path */
 
-   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, write to the Free Software Foundation,
-   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
-
-#ifdef HAVE_CONFIG_H
+#if HAVE_CONFIG_H
 # include <config.h>
 #endif
 
-/* Return NAME with any leading path stripped off.
-   Don't use strrchr/rindex.  */
+#include <backupfile.h>
+
+#ifndef FILESYSTEM_PREFIX_LEN
+#define FILESYSTEM_PREFIX_LEN(f) 0
+#endif
+
+#ifndef ISSLASH
+#define ISSLASH(c) ((c) == '/')
+#endif
+
+/* In general, we can't use the builtin `basename' function if available,
+   since it has different meanings in different environments.
+   In some environments the builtin `basename' modifies its argument.  */
 
 char *
-basename (name)
-     const char *name;
+base_name (name)
+     char const *name;
 {
-  const char *base = name;
+  char const *base = name += FILESYSTEM_PREFIX_LEN (name);
 
-  while (*name)
-    {
-      if (*name == '/')
-	base = name + 1;
-      ++name;
-    }
+  for (; *name; name++)
+    if (ISSLASH (*name))
+      base = name + 1;
+
   return (char *) base;
 }