/* * Compute the relative path needed to go from one Unix dir to another * * Copyright 2006 Alexandre Julliard * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA */ #include "config.h" #include <stdio.h> #include <stdlib.h> #include <string.h> /* determine where the destination path is located relative to the 'from' path */ static const char *get_relative_path( const char *from, const char *dest, unsigned int *dotdots ) { #define DIR_END(p) (*(p) == 0 || *(p) == '/') const char *start; /* a path of "." is equivalent to an empty path */ if (!strcmp( from, "." )) from = ""; *dotdots = 0; for (;;) { while (*from == '/') from++; while (*dest == '/') dest++; start = dest; /* save start of next path element */ if (!*from) break; while (!DIR_END(from) && *from == *dest) { from++; dest++; } if (DIR_END(from) && DIR_END(dest)) continue; /* count remaining elements in 'from' */ do { (*dotdots)++; while (!DIR_END(from)) from++; while (*from == '/') from++; } while (*from); break; } return start; #undef DIR_END } int main( int argc, char *argv[] ) { const char *start; unsigned int dotdots = 0; if (argc != 3) { fprintf( stderr, "Usage: %s fromdir todir\n", argv[0] ); exit(1); } start = get_relative_path( argv[1], argv[2], &dotdots ); if (!start[0] && !dotdots) printf( ".\n" ); else { while (dotdots) { printf( ".." ); dotdots--; if (dotdots || start[0]) printf( "/" ); } printf( "%s\n", start ); } exit(0); }