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110 lines
3.1 KiB
C
110 lines
3.1 KiB
C
/*
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* Copyright (c) 1997 Shigio Yamaguchi. All rights reserved.
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* Copyright (c) 1999 Tama Communications Corporation. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include "pathconv.h" /* prototypes */
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/*
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* abs2rel: convert an absolute path name into relative.
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*
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* i) path absolute path
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* i) base base directory (must be absolute path)
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* o) result result buffer
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* i) size size of result buffer
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* r) != NULL: relative path
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* == NULL: error
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*/
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char *
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abs2rel(const char *path, const char *base, char *result, const size_t size)
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{
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const char *pp, *bp, *branch;
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/*
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* endp points the last position which is safe in the result buffer.
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*/
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const char *endp = result + size - 1;
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char *rp;
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if (*path != '/') {
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if (strlen(path) >= size)
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goto erange;
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strcpy(result, path);
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goto finish;
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} else if (*base != '/' || !size) {
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errno = EINVAL;
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return (NULL);
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} else if (size == 1)
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goto erange;
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/*
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* seek to branched point.
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*/
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branch = path;
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for (pp = path, bp = base; *pp && *bp && *pp == *bp; pp++, bp++)
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if (*pp == '/')
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branch = pp;
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if ((*pp == 0 || (*pp == '/' && *(pp + 1) == 0)) &&
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(*bp == 0 || (*bp == '/' && *(bp + 1) == 0))) {
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rp = result;
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*rp++ = '.';
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if (*pp == '/' || *(pp - 1) == '/')
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*rp++ = '/';
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if (rp > endp)
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goto erange;
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*rp = 0;
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goto finish;
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}
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if ((*pp == 0 && *bp == '/') || (*pp == '/' && *bp == 0))
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branch = pp;
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/*
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* up to root.
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*/
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rp = result;
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for (bp = base + (branch - path); *bp; bp++)
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if (*bp == '/' && *(bp + 1) != 0) {
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if (rp + 3 > endp)
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goto erange;
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*rp++ = '.';
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*rp++ = '.';
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*rp++ = '/';
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}
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if (rp > endp)
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goto erange;
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*rp = 0;
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/*
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* down to leaf.
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*/
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if (*branch) {
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if (rp + strlen(branch + 1) > endp)
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goto erange;
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strcpy(rp, branch + 1);
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} else
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*--rp = 0;
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finish:
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return result;
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erange:
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errno = ERANGE;
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return (NULL);
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}
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