--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/basename.c	Tue Dec 22 05:31:23 2009 +0000
@@ -0,0 +1,128 @@
+/* basename.c -- return the last element in a file name
+
+   Copyright (C) 1990, 1998, 1999, 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"
+#include "xstrndup.h"
+
+/* Return the address of the last file name component of NAME.  If
+   NAME has no relative file name components because it is a file
+   system root, return the empty string.  */
+
+char *
+last_component (char const *name)
+{
+  char const *base = name + FILE_SYSTEM_PREFIX_LEN (name);
+  char const *p;
+  bool saw_slash = false;
+
+  while (ISSLASH (*base))
+    base++;
+
+  for (p = base; *p; p++)
+    {
+      if (ISSLASH (*p))
+	saw_slash = true;
+      else if (saw_slash)
+	{
+	  base = p;
+	  saw_slash = false;
+	}
+    }
+
+  return (char *) base;
+}
+
+
+/* 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.
+
+   Return the last file name component of NAME, allocated with
+   xmalloc.  On systems with drive letters, a leading "./"
+   distinguishes relative names that would otherwise look like a drive
+   letter.  Unlike POSIX basename(), NAME cannot be NULL,
+   base_name("") returns "", and the first trailing slash is not
+   stripped.
+
+   If lstat (NAME) would succeed, then { chdir (dir_name (NAME));
+   lstat (base_name (NAME)); } will access the same file.  Likewise,
+   if the sequence { chdir (dir_name (NAME));
+   rename (base_name (NAME), "foo"); } succeeds, you have renamed NAME
+   to "foo" in the same directory NAME was in.  */
+
+char *
+base_name (char const *name)
+{
+  char const *base = last_component (name);
+  size_t length;
+
+  /* If there is no last component, then name is a file system root or the
+     empty string.  */
+  if (! *base)
+    return xstrndup (name, base_len (name));
+
+  /* Collapse a sequence of trailing slashes into one.  */
+  length = base_len (base);
+  if (ISSLASH (base[length]))
+    length++;
+
+  /* On systems with drive letters, `a/b:c' must return `./b:c' rather
+     than `b:c' to avoid confusion with a drive letter.  On systems
+     with pure POSIX semantics, this is not an issue.  */
+  if (FILE_SYSTEM_PREFIX_LEN (base))
+    {
+      char *p = xmalloc (length + 3);
+      p[0] = '.';
+      p[1] = '/';
+      memcpy (p + 2, base, length);
+      p[length + 2] = '\0';
+      return p;
+    }
+
+  /* Finally, copy the basename.  */
+  return xstrndup (base, length);
+}
+
+/* Return the length of the basename NAME.  Typically NAME is the
+   value returned by base_name or last_component.  Act like strlen
+   (NAME), except omit all trailing slashes.  */
+
+size_t
+base_len (char const *name)
+{
+  size_t len;
+  size_t prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
+
+  for (len = strlen (name);  1 < len && ISSLASH (name[len - 1]);  len--)
+    continue;
+
+  if (DOUBLE_SLASH_IS_DISTINCT_ROOT && len == 1
+      && ISSLASH (name[0]) && ISSLASH (name[1]) && ! name[2])
+    return 2;
+
+  if (FILE_SYSTEM_DRIVE_PREFIX_CAN_BE_RELATIVE && prefix_len
+      && len == prefix_len && ISSLASH (name[prefix_len]))
+    return prefix_len + 1;
+
+  return len;
+}