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https://github.com/licsber/micropython.git
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32db4c58f7
The primary purpose of this commit is to make decompress default to wbits=15 when the format is gzip (or auto format with gzip detected). The idea is that someone decompressing a gzip stream should be able to use the default `deflate.DeflateIO(f)` and it will "just work" for any input stream, even though it uses a lot of memory. This is done by making uzlib report gzip files as having wbits set to 15 in their header (where it previously only set the wbits out parameter for zlib files), and then fixing up the logic in `deflateio_init_read`. Updates the documentation to match. This work was funded through GitHub Sponsors. Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
138 lines
3.8 KiB
C
138 lines
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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