72 lines
2.2 KiB
C
72 lines
2.2 KiB
C
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/*
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zip_filerange_crc.c -- compute CRC32 for a range of a file
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Copyright (C) 2008 Dieter Baron and Thomas Klausner
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This file is part of libzip, a library to manipulate ZIP archives.
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The authors can be contacted at <libzip@nih.at>
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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
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the documentation and/or other materials provided with the
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distribution.
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3. The names of the authors may not be used to endorse or promote
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products derived from this software without specific prior
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written permission.
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THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
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OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
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IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdio.h>
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#include <errno.h>
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#include "zipint.h"
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int
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_zip_filerange_crc(FILE *fp, off_t start, off_t len, uLong *crcp,
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struct zip_error *errp)
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{
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Bytef buf[BUFSIZE];
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size_t n;
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*crcp = crc32(0L, Z_NULL, 0);
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if (fseeko(fp, start, SEEK_SET) != 0) {
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_zip_error_set(errp, ZIP_ER_SEEK, errno);
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return -1;
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}
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while (len > 0) {
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n = len > BUFSIZE ? BUFSIZE : len;
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if ((n=fread(buf, 1, n, fp)) <= 0) {
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_zip_error_set(errp, ZIP_ER_READ, errno);
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return -1;
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}
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*crcp = crc32(*crcp, buf, n);
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len-= n;
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}
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return 0;
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}
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