limine/tinf/tinfgzip.c

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/*
* tinfgzip - tiny gzip decompressor
*
* Copyright (c) 2003-2019 Joergen Ibsen
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must
* not claim that you wrote the original software. If you use this
* software in a product, an acknowledgment in the product
* documentation would be appreciated but is not required.
*
* 2. Altered source versions must be plainly marked as such, and must
* not be misrepresented as being the original software.
*
* 3. This notice may not be removed or altered from any source
* distribution.
*/
#include "tinf.h"
typedef enum {
FTEXT = 1,
FHCRC = 2,
FEXTRA = 4,
FNAME = 8,
FCOMMENT = 16
} tinf_gzip_flag;
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int tinf_gzip_uncompress(void *dest,
const void *source, unsigned int sourceLen) {
const unsigned char *src = (const unsigned char *) source;
unsigned char *dst = (unsigned char *) dest;
const unsigned char *start;
int res;
unsigned char flg;
/* -- Check header -- */
/* Check room for at least 10 byte header and 8 byte trailer */
if (sourceLen < 18) {
return TINF_DATA_ERROR;
}
/* Check id bytes */
if (src[0] != 0x1F || src[1] != 0x8B) {
return TINF_DATA_ERROR;
}
/* Check method is deflate */
if (src[2] != 8) {
return TINF_DATA_ERROR;
}
/* Get flag byte */
flg = src[3];
/* Check that reserved bits are zero */
if (flg & 0xE0) {
return TINF_DATA_ERROR;
}
/* -- Find start of compressed data -- */
/* Skip base header of 10 bytes */
start = src + 10;
/* Skip extra data if present */
if (flg & FEXTRA) {
unsigned int xlen = *start;
if (xlen > sourceLen - 12) {
return TINF_DATA_ERROR;
}
start += xlen + 2;
}
/* Skip file name if present */
if (flg & FNAME) {
do {
if (((unsigned int)(start - src)) >= sourceLen) {
return TINF_DATA_ERROR;
}
} while (*start++);
}
/* Skip file comment if present */
if (flg & FCOMMENT) {
do {
if (((unsigned int)(start - src)) >= sourceLen) {
return TINF_DATA_ERROR;
}
} while (*start++);
}
if (flg & FHCRC) {
start += 2;
}
/* -- Decompress data -- */
if ((src + sourceLen) - start < 8) {
return TINF_DATA_ERROR;
}
res = tinf_uncompress(dst, start,
(src + sourceLen) - start - 8);
if (res != TINF_OK) {
return TINF_DATA_ERROR;
}
return TINF_OK;
}