1: /* dirname - return directory part of PATH.
    2:    Copyright (C) 1996, 2000, 2001, 2002 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 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 <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 != NULL && last_slash != path && last_slash[1] == '\0')
   35:     {
   36:       /* Determine whether all remaining characters are slashes.  */
   37:       char *runp;
   38: 
   39:       for (runp = last_slash; runp != path; --runp)
   40:         if (runp[-1] != '/')
   41:           break;
   42: 
   43:       /* The '/' is the last character, we have to look further.  */
   44:       if (runp != path)
   45:         last_slash = __memrchr (path, '/', runp - path);
   46:     }
   47: 
   48:   if (last_slash != NULL)
   49:     {
   50:       /* Determine whether all remaining characters are slashes.  */
   51:       char *runp;
   52: 
   53:       for (runp = last_slash; runp != path; --runp)
   54:         if (runp[-1] != '/')
   55:           break;
   56: 
   57:       /* Terminate the path.  */
   58:       if (runp == path)
   59:         {
   60:           /* The last slash is the first character in the string.  We have to
   61:              return "/".  As a special case we have to return "//" if there
   62:              are exactly two slashes at the beginning of the string.  See
   63:              XBD 4.10 Path Name Resolution for more information.  */
   64:           if (last_slash == path + 1)
   65:             ++last_slash;
   66:           else
   67:             last_slash = path + 1;
   68:         }
   69:       else
   70:         last_slash = runp;
   71: 
   72:       last_slash[0] = '\0';
   73:     }
   74:   else
   75:     /* This assignment is ill-designed but the XPG specs require to
   76:        return a string containing "." in any case no directory part is
   77:        found and so a static and constant string is required.  */
   78:     path = (char *) dot;
   79: 
   80:   return path;
   81: }