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/*
* 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.
*
* 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.
*
* $FreeBSD$
*/
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "pathconv.h" /* prototypes */
/*
* abs2rel: convert an absolute path name into relative.
*
* i) path absolute path
* i) base base directory (must be absolute path)
* o) result result buffer
* i) size size of result buffer
* r) != NULL: relative path
* == NULL: error
*/
char *
abs2rel(const char *path, const char *base, char *result, const size_t size)
{
const char *pp, *bp, *branch;
/*
* endp points the last position which is safe in the result buffer.
*/
const char *endp = result + size - 1;
char *rp;
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);
}
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