usr.bin/relpath/relpath.c

   1 /*
   2  * Copyright (c) 2003 Matthew Dillon <dillon@backplane.com>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $DragonFly: src/usr.bin/relpath/relpath.c,v 1.2 2004/12/28 19:50:11 liamfoy Exp $
  27  *
  28  * relpath base path
  29  *
  30  * This program returns a path for 'path' which is relative to the specified
  31  * base.
  32  */
  33
  34 #include <sys/stat.h>
  35
  36 #include <err.h>
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include <string.h>
  40
  41 int
  42 main(int ac, char **av)
  43 {
  44     char *path;
  45     char *rbase;
  46     struct stat st1;
  47     struct stat st2;
  48     int error;
  49
  50     if (ac != 3) {
  51         fprintf(stderr, "%s base path\n", av[0]);
  52         fprintf(stderr, "\treturns a relative path for path from base\n");
  53         exit(1);
  54     }
  55     if (stat(av[1], &st1) < 0)
  56         err(1, "Unable to stat %s", av[1]);
  57
  58     path = strdup(av[2]);
  59     rbase = path + strlen(path);
  60     for (;;) {
  61         while (rbase > path && rbase[-1] != '/')
  62             --rbase;
  63         if (rbase == path)
  64             break;
  65         --rbase;
  66         *rbase = 0;
  67         error = stat(path, &st2);
  68         *rbase = '/';
  69         if (error == 0 &&
  70             st2.st_dev == st1.st_dev &&
  71             st2.st_ino == st1.st_ino
  72         ) {
  73                 printf("%s\n", rbase + 1);
  74                 exit(0);
  75         }
  76     }
  77     fprintf(stderr, "%s is not a subdirectory of %s\n", av[2], av[1]);
  78     exit(1);
  79 }
  80