add basename.c

+/* basename.c -- return the last element in a path
+   Copyright (C) 1990, 1998, 1999, 2000, 2001 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.
+
+   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.  */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdio.h>
+#include <assert.h>
+
+#ifndef FILESYSTEM_PREFIX_LEN
+# define FILESYSTEM_PREFIX_LEN(Filename) 0
+#endif
+
+#ifndef PARAMS
+# if defined PROTOTYPES || (defined __STDC__ && __STDC__)
+#  define PARAMS(Args) Args
+# else
+#  define PARAMS(Args) ()
+# endif
+#endif
+
+#ifndef ISSLASH
+# define ISSLASH(C) ((C) == '/')
+#endif
+
+char *base_name PARAMS ((char const *name));
+
+/* 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.
+   If NAME is all slashes, be sure to return `/'.  */
+
+char *
+base_name (char const *name)
+{
+  char const *base = name += FILESYSTEM_PREFIX_LEN (name);
+  int all_slashes = 1;
+  char const *p;
+
+  for (p = name; *p; p++)
+    {
+      if (ISSLASH (*p))
+	base = p + 1;
+      else
+	all_slashes = 0;
+    }
+
+  /* If NAME is all slashes, arrange to return `/'.  */
+  if (*base == '\0' && ISSLASH (*name) && all_slashes)
+    --base;
+
+  /* Make sure the last byte is not a slash.  */
+  assert (all_slashes || !ISSLASH (*(p - 1)));
+
+  return (char *) base;
+}