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| 1 | +/* |
| 2 | + * tinfgzip - tiny gzip decompressor |
| 3 | + * |
| 4 | + * Copyright (c) 2003 by Joergen Ibsen / Jibz |
| 5 | + * All Rights Reserved |
| 6 | + * |
| 7 | + * http://www.ibsensoftware.com/ |
| 8 | + * |
| 9 | + * Copyright (c) 2014-2016 by Paul Sokolovsky |
| 10 | + * |
| 11 | + * This software is provided 'as-is', without any express |
| 12 | + * or implied warranty. In no event will the authors be |
| 13 | + * held liable for any damages arising from the use of |
| 14 | + * this software. |
| 15 | + * |
| 16 | + * Permission is granted to anyone to use this software |
| 17 | + * for any purpose, including commercial applications, |
| 18 | + * and to alter it and redistribute it freely, subject to |
| 19 | + * the following restrictions: |
| 20 | + * |
| 21 | + * 1. The origin of this software must not be |
| 22 | + * misrepresented; you must not claim that you |
| 23 | + * wrote the original software. If you use this |
| 24 | + * software in a product, an acknowledgment in |
| 25 | + * the product documentation would be appreciated |
| 26 | + * but is not required. |
| 27 | + * |
| 28 | + * 2. Altered source versions must be plainly marked |
| 29 | + * as such, and must not be misrepresented as |
| 30 | + * being the original software. |
| 31 | + * |
| 32 | + * 3. This notice may not be removed or altered from |
| 33 | + * any source distribution. |
| 34 | + */ |
| 35 | + |
| 36 | +#include "tinf.h" |
| 37 | + |
| 38 | +#define FTEXT 1 |
| 39 | +#define FHCRC 2 |
| 40 | +#define FEXTRA 4 |
| 41 | +#define FNAME 8 |
| 42 | +#define FCOMMENT 16 |
| 43 | + |
| 44 | +void tinf_skip_bytes(TINF_DATA *d, int num) |
| 45 | +{ |
| 46 | + while (num--) uzlib_get_byte(d); |
| 47 | +} |
| 48 | + |
| 49 | +uint16_t tinf_get_uint16(TINF_DATA *d) |
| 50 | +{ |
| 51 | + unsigned int v = uzlib_get_byte(d); |
| 52 | + v = (uzlib_get_byte(d) << 8) | v; |
| 53 | + return v; |
| 54 | +} |
| 55 | + |
| 56 | +int uzlib_gzip_parse_header(TINF_DATA *d) |
| 57 | +{ |
| 58 | + unsigned char flg; |
| 59 | + |
| 60 | + /* -- check format -- */ |
| 61 | + |
| 62 | + /* check id bytes */ |
| 63 | + if (uzlib_get_byte(d) != 0x1f || uzlib_get_byte(d) != 0x8b) return TINF_DATA_ERROR; |
| 64 | + |
| 65 | + /* check method is deflate */ |
| 66 | + if (uzlib_get_byte(d) != 8) return TINF_DATA_ERROR; |
| 67 | + |
| 68 | + /* get flag byte */ |
| 69 | + flg = uzlib_get_byte(d); |
| 70 | + |
| 71 | + /* check that reserved bits are zero */ |
| 72 | + if (flg & 0xe0) return TINF_DATA_ERROR; |
| 73 | + |
| 74 | + /* -- find start of compressed data -- */ |
| 75 | + |
| 76 | + /* skip rest of base header of 10 bytes */ |
| 77 | + tinf_skip_bytes(d, 6); |
| 78 | + |
| 79 | + /* skip extra data if present */ |
| 80 | + if (flg & FEXTRA) |
| 81 | + { |
| 82 | + unsigned int xlen = tinf_get_uint16(d); |
| 83 | + tinf_skip_bytes(d, xlen); |
| 84 | + } |
| 85 | + |
| 86 | + /* skip file name if present */ |
| 87 | + if (flg & FNAME) { while (uzlib_get_byte(d)); } |
| 88 | + |
| 89 | + /* skip file comment if present */ |
| 90 | + if (flg & FCOMMENT) { while (uzlib_get_byte(d)); } |
| 91 | + |
| 92 | + /* check header crc if present */ |
| 93 | + if (flg & FHCRC) |
| 94 | + { |
| 95 | + /*unsigned int hcrc =*/ tinf_get_uint16(d); |
| 96 | + |
| 97 | + // TODO: Check! |
| 98 | +// if (hcrc != (tinf_crc32(src, start - src) & 0x0000ffff)) |
| 99 | +// return TINF_DATA_ERROR; |
| 100 | + } |
| 101 | + |
| 102 | + /* initialize for crc32 checksum */ |
| 103 | + d->checksum_type = TINF_CHKSUM_CRC; |
| 104 | + d->checksum = ~0; |
| 105 | + |
| 106 | + return TINF_OK; |
| 107 | +} |
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