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Alexandre Julliard35842ca2006-02-17 11:42:17 +01001/*
2 * Compute the relative path needed to go from one Unix dir to another
3 *
4 * Copyright 2006 Alexandre Julliard
5 *
6 * This 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 * This 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 this library; if not, write to the Free Software
Jonathan Ernst360a3f92006-05-18 14:49:52 +020018 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
Alexandre Julliard35842ca2006-02-17 11:42:17 +010019 */
20
21#include "config.h"
22
23#include <stdio.h>
24#include <stdlib.h>
25#include <string.h>
26
27/* determine where the destination path is located relative to the 'from' path */
28static const char *get_relative_path( const char *from, const char *dest, unsigned int *dotdots )
29{
30#define DIR_END(p) (*(p) == 0 || *(p) == '/')
31 const char *start;
32
33 *dotdots = 0;
34 for (;;)
35 {
36 while (*from == '/') from++;
37 while (*dest == '/') dest++;
38 start = dest; /* save start of next path element */
39 if (!*from) break;
40
41 while (!DIR_END(from) && *from == *dest) { from++; dest++; }
42 if (DIR_END(from) && DIR_END(dest)) continue;
43
44 /* count remaining elements in 'from' */
45 do
46 {
47 (*dotdots)++;
48 while (!DIR_END(from)) from++;
49 while (*from == '/') from++;
50 }
51 while (*from);
52 break;
53 }
54 return start;
55#undef DIR_END
56}
57
58
59int main( int argc, char *argv[] )
60{
61 const char *start;
62 unsigned int dotdots = 0;
63
64 if (argc != 3)
65 {
66 fprintf( stderr, "Usage: %s fromdir todir\n", argv[0] );
67 exit(1);
68 }
69 start = get_relative_path( argv[1], argv[2], &dotdots );
70
71 if (!start[0] && !dotdots) printf( ".\n" );
72 else
73 {
74 while (dotdots)
75 {
76 printf( ".." );
77 dotdots--;
78 if (dotdots || start[0]) printf( "/" );
79 }
80 printf( "%s\n", start );
81 }
82 exit(0);
83}