misc/dirname.c

   1 /* dirname - return directory part of PATH.
   2    Copyright (C) 1996 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <libgen.h>
  22 #include <string.h>
  23
  24
  25 char *
  26 dirname (char *path)
  27 {
  28   static const char dot[] = ".";
  29   char *last_slash;
  30
  31   /* Find last '/'.  */
  32   last_slash = path != NULL ? strrchr (path, '/') : NULL;
  33
  34   if (last_slash == path)
  35     /* The last slash is the first character in the string.  We have to
  36        return "/".  */
  37     ++last_slash;
  38   else if (last_slash != NULL && last_slash[1] == '\0')
  39     /* The '/' is the last character, we have to look further.  */
  40     last_slash = memchr (path, last_slash - path, '/');
  41
  42   if (last_slash != NULL)
  43     /* Terminate the path.  */
  44     last_slash[0] = '\0';
  45   else
  46     /* This assignment is ill-designed but the XPG specs require to
  47        return a string containing "." in any case no directory part is
  48        found and so a static and constant string is required.  */
  49     path = (char *) dot;
  50
  51   return path;
  52 }