ossp-pkg/path/path_abs2rel.c
1.3
/*
** OSSP path - Filesystem Path Manipulation
** Copyright (c) 2002 Ralf S. Engelschall <rse@engelschall.com>
** Copyright (c) 2002 The OSSP Project <http://www.ossp.org/>
** Copyright (c) 2002 Cable & Wireless Deutschland <http://www.cw.com/de/>
**
** This file is part of OSSP path, a filesystem path manipulation library
** which can be found at http://www.ossp.org/pkg/lib/path/.
**
** Permission to use, copy, modify, and distribute this software for
** any purpose with or without fee is hereby granted, provided that
** the above copyright notice and this permission notice appear in all
** copies.
**
** THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
** USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
** OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
** SUCH DAMAGE.
**
** path_abs2rel.c: absolute to relative path translation
*/
/*
* Copyright (c) 1997 Shigio Yamaguchi. All rights reserved.
* Copyright (c) 1999 Tama Communications Corporation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Tama Communications
* Corporation.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "path.h"
/*
* abs2rel: convert an absolute path name into relative.
*/
char *
path_abs2rel(
char *result,
size_t size,
const char *path,
const char *base)
{
const char *pp, *bp, *branch;
const char *endp;
char *rp;
/* endp points the last position which is safe in the result buffer. */
endp = result + size - 1;
if (*path != '/') {
if (strlen(path) >= size)
goto erange;
strcpy(result, path);
goto finish;
}
else if (*base != '/' || !size) {
errno = EINVAL;
return NULL;
}
else if (size == 1) {
goto erange;
}
/*
* seek to branched point.
*/
branch = path;
for (pp = path, bp = base; *pp && *bp && *pp == *bp; pp++, bp++)
if (*pp == '/')
branch = pp;
if ((*pp == 0 || (*pp == '/' && *(pp + 1) == 0)) &&
(*bp == 0 || (*bp == '/' && *(bp + 1) == 0))) {
rp = result;
*rp++ = '.';
if (*pp == '/' || *(pp - 1) == '/')
*rp++ = '/';
if (rp > endp)
goto erange;
*rp = 0;
goto finish;
}
if ((*pp == 0 && *bp == '/') || (*pp == '/' && *bp == 0))
branch = pp;
/*
* up to root.
*/
rp = result;
for (bp = base + (branch - path); *bp; bp++) {
if (*bp == '/' && *(bp + 1) != 0) {
if (rp + 3 > endp)
goto erange;
*rp++ = '.';
*rp++ = '.';
*rp++ = '/';
}
}
if (rp > endp)
goto erange;
*rp = 0;
/*
* down to leaf.
*/
if (*branch) {
if (rp + strlen(branch + 1) > endp)
goto erange;
strcpy(rp, branch + 1);
}
else {
*--rp = 0;
}
finish:
return result;
erange:
errno = ERANGE;
return NULL;
}
