stdlib/xpg_basename.c

   1 /* Return basename of given pathname according to the weird XPG specification.
   2    Copyright (C) 1997, 1999 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library 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 GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <string.h>
  22 #include <libgen.h>
  23
  24
  25 char *
  26 __xpg_basename (char *filename)
  27 {
  28   char *p;
  29
  30   if (filename == NULL || filename[0] == '\0')
  31     /* We return a pointer to a static string containing ".".  */
  32     p = (char *) ".";
  33   else
  34     {
  35       p = strrchr (filename, '/');
  36
  37       if (p == NULL)
  38         /* There is no slash in the filename.  Return the whole string.  */
  39         p = filename;
  40       else
  41         {
  42           if (p[1] == '\0')
  43             {
  44               /* We must remove trailing '/'.  */
  45               while (p > filename && p[-1] == '/')
  46                 --p;
  47
  48               /* Now we can be in two situations:
  49                  a) the string only contains '/' characters, so we return
  50                     '/'
  51                  b) p points past the last component, but we have to remove
  52                     the trailing slash.  */
  53               if (p > filename)
  54                 {
  55                   *p-- = '\0';
  56                   while (p > filename && p[-1] != '/')
  57                     --p;
  58                 }
  59               else
  60                 /* The last slash we already found is the right position
  61                    to return.  */
  62                 while (p[1] != '\0')
  63                   ++p;
  64             }
  65           else
  66             /* Go to the first character of the name.  */
  67             ++p;
  68         }
  69     }
  70
  71   return p;
  72 }