lib/basename.c

   1 /* basename.c -- return the last element in a file name
   2
   3    Copyright (C) 1990, 1998-2001, 2003-2006, 2009-2018 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #include <config.h>
  20
  21 #include "dirname.h"
  22
  23 #include <string.h>
  24 #include "xalloc.h"
  25 #include "xstrndup.h"
  26
  27 char *
  28 base_name (char const *name)
  29 {
  30   char const *base = last_component (name);
  31   size_t length;
  32
  33   /* If there is no last component, then name is a file system root or the
  34      empty string.  */
  35   if (! *base)
  36     return xstrndup (name, base_len (name));
  37
  38   /* Collapse a sequence of trailing slashes into one.  */
  39   length = base_len (base);
  40   if (ISSLASH (base[length]))
  41     length++;
  42
  43   /* On systems with drive letters, "a/b:c" must return "./b:c" rather
  44      than "b:c" to avoid confusion with a drive letter.  On systems
  45      with pure POSIX semantics, this is not an issue.  */
  46   if (FILE_SYSTEM_PREFIX_LEN (base))
  47     {
  48       char *p = xmalloc (length + 3);
  49       p[0] = '.';
  50       p[1] = '/';
  51       memcpy (p + 2, base, length);
  52       p[length + 2] = '\0';
  53       return p;
  54     }
  55
  56   /* Finally, copy the basename.  */
  57   return xstrndup (base, length);
  58 }