usr/src/lib/libast/common/comp/dirname.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #pragma prototyped
  23 /*
  24  * dirname(3) implementation
  25  */
  26
  27 #include <ast_std.h>
  28
  29 #if defined(__EXPORT__)
  30 #define extern  __EXPORT__
  31 #endif
  32
  33 extern char *dirname(register char *pathname)
  34 {
  35         register char  *last;
  36         /* go to end of path */
  37         for(last=pathname; *last; last++);
  38         /* back over trailing '/' */
  39         while(last>pathname && *--last=='/');
  40         /* back over non-slash chars */
  41         for(;last>pathname && *last!='/';last--);
  42         if(last==pathname)
  43         {
  44                 /* all '/' or "" */
  45                 if(*last!='/')
  46                         *last = '.';
  47                 /* preserve // */
  48                 else if(last[1]=='/')
  49                         last++;
  50         }
  51         else
  52         {
  53                 /* back over trailing '/' */
  54                 for(;*last=='/' && last > pathname; last--);
  55                 /* preserve // */
  56                 if(last==pathname && *pathname=='/' && pathname[1]=='/')
  57                         last++;
  58         }
  59         *(last + 1) = 0;
  60         return(pathname);
  61 }