kopia lustrzana https://github.com/micropython/micropython
138 wiersze
3.8 KiB
C
138 wiersze
3.8 KiB
C
/*
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* uzlib - tiny deflate/inflate library (deflate, gzip, zlib)
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*
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* Copyright (c) 2003 by Joergen Ibsen / Jibz
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* All Rights Reserved
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*
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* http://www.ibsensoftware.com/
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*
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* Copyright (c) 2014-2018 by Paul Sokolovsky
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*
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* Optimised for MicroPython:
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* Copyright (c) 2023 by Jim Mussared
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*
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* This software is provided 'as-is', without any express
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* or implied warranty. In no event will the authors be
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* held liable for any damages arising from the use of
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* this software.
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*
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* Permission is granted to anyone to use this software
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* for any purpose, including commercial applications,
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* and to alter it and redistribute it freely, subject to
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* the following restrictions:
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*
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* 1. The origin of this software must not be
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* misrepresented; you must not claim that you
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* wrote the original software. If you use this
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* software in a product, an acknowledgment in
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* the product documentation would be appreciated
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* but is not required.
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*
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* 2. Altered source versions must be plainly marked
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* as such, and must not be misrepresented as
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* being the original software.
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*
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* 3. This notice may not be removed or altered from
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* any source distribution.
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*/
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#include "uzlib.h"
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#define FTEXT 1
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#define FHCRC 2
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#define FEXTRA 4
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#define FNAME 8
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#define FCOMMENT 16
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void tinf_skip_bytes(uzlib_uncomp_t *d, int num);
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uint16_t tinf_get_uint16(uzlib_uncomp_t *d);
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void tinf_skip_bytes(uzlib_uncomp_t *d, int num)
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{
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while (num--) uzlib_get_byte(d);
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}
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uint16_t tinf_get_uint16(uzlib_uncomp_t *d)
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{
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unsigned int v = uzlib_get_byte(d);
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v = (uzlib_get_byte(d) << 8) | v;
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return v;
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}
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int uzlib_parse_zlib_gzip_header(uzlib_uncomp_t *d, int *wbits)
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{
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/* -- check format -- */
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unsigned char cmf = uzlib_get_byte(d);
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unsigned char flg = uzlib_get_byte(d);
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/* check for gzip id bytes */
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if (cmf == 0x1f && flg == 0x8b) {
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/* check method is deflate */
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if (uzlib_get_byte(d) != 8) return UZLIB_DATA_ERROR;
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/* get flag byte */
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flg = uzlib_get_byte(d);
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/* check that reserved bits are zero */
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if (flg & 0xe0) return UZLIB_DATA_ERROR;
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/* -- find start of compressed data -- */
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/* skip rest of base header of 10 bytes */
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tinf_skip_bytes(d, 6);
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/* skip extra data if present */
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if (flg & FEXTRA)
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{
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unsigned int xlen = tinf_get_uint16(d);
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tinf_skip_bytes(d, xlen);
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}
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/* skip file name if present */
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if (flg & FNAME) { while (uzlib_get_byte(d)); }
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/* skip file comment if present */
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if (flg & FCOMMENT) { while (uzlib_get_byte(d)); }
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/* check header crc if present */
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if (flg & FHCRC)
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{
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/*unsigned int hcrc =*/ tinf_get_uint16(d);
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// TODO: Check!
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// if (hcrc != (tinf_crc32(src, start - src) & 0x0000ffff))
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// return UZLIB_DATA_ERROR;
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}
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/* initialize for crc32 checksum */
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d->checksum_type = UZLIB_CHKSUM_CRC;
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d->checksum = ~0;
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/* gzip does not include the window size in the header, as it is expected that a
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compressor will use wbits=15 (32kiB).*/
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*wbits = 15;
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return UZLIB_HEADER_GZIP;
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} else {
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/* check checksum */
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if ((256*cmf + flg) % 31) return UZLIB_DATA_ERROR;
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/* check method is deflate */
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if ((cmf & 0x0f) != 8) return UZLIB_DATA_ERROR;
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/* check window size is valid */
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if ((cmf >> 4) > 7) return UZLIB_DATA_ERROR;
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/* check there is no preset dictionary */
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if (flg & 0x20) return UZLIB_DATA_ERROR;
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/* initialize for adler32 checksum */
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d->checksum_type = UZLIB_CHKSUM_ADLER;
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d->checksum = 1;
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*wbits = (cmf >> 4) + 8;
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return UZLIB_HEADER_ZLIB;
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}
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}
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