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/*
* tinfgzip - tiny gzip decompressor
*
* Copyright (c) 2003-2019 Joergen Ibsen
*
* This version of tinfzlib was modified for use with m1n1.
*
* 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;
static unsigned int read_le16(const unsigned char *p)
{
return ((unsigned int) p[0])
| ((unsigned int) p[1] << 8);
}
static unsigned int read_le32(const unsigned char *p)
{
return ((unsigned int) p[0])
| ((unsigned int) p[1] << 8)
| ((unsigned int) p[2] << 16)
| ((unsigned int) p[3] << 24);
}
int tinf_gzip_uncompress(void *dest, unsigned int *destLen,
const void *source, unsigned int *sourceLen)
{
const unsigned char *src = (const unsigned char *) source;
unsigned char *dst = (unsigned char *) dest;
const unsigned char *start;
unsigned int dlen, crc32;
int res;
unsigned char flg;
unsigned int sourceDataLen = 0;
/* -- Check header -- */
/* Check room for at least 10 byte header and 8 byte trailer */
if (*sourceLen && *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 = read_le16(start);
if (*sourceLen && xlen > *sourceLen - 12) {
return TINF_DATA_ERROR;
}
start += xlen + 2;
}
/* Skip file name if present */
if (flg & FNAME) {
do {
if (*sourceLen && start - src >= *sourceLen) {
return TINF_DATA_ERROR;
}
} while (*start++);
}
/* Skip file comment if present */
if (flg & FCOMMENT) {
do {
if (*sourceLen && start - src >= *sourceLen) {
return TINF_DATA_ERROR;
}
} while (*start++);
}
/* Check header crc if present */
if (flg & FHCRC) {
unsigned int hcrc;
if (*sourceLen && start - src > *sourceLen - 2) {
return TINF_DATA_ERROR;
}
hcrc = read_le16(start);
if (hcrc != (tinf_crc32(src, start - src) & 0x0000FFFF)) {
return TINF_DATA_ERROR;
}
start += 2;
}
/* -- Get decompressed length if available -- */
if (*sourceLen) {
dlen = read_le32(&src[*sourceLen - 4]);
if (dlen > *destLen) {
return TINF_BUF_ERROR;
}
}
/* -- Check source length if available -- */
if (*sourceLen) {
if ((src + *sourceLen) - start < 8) {
return TINF_DATA_ERROR;
}
sourceDataLen = (src + *sourceLen) - start - 8;
}
/* -- Decompress data -- */
res = tinf_uncompress(dst, destLen, start, &sourceDataLen);
if (res != TINF_OK) {
return TINF_DATA_ERROR;
}
sourceDataLen += (start - src) + 8;
if (*sourceLen && *sourceLen != sourceDataLen) {
return TINF_DATA_ERROR;
}
*sourceLen = sourceDataLen;
/* -- Check decompressed length -- */
dlen = read_le32(&src[*sourceLen - 4]);
if (*destLen != dlen) {
return TINF_DATA_ERROR;
}
/* -- Check CRC32 checksum -- */
crc32 = read_le32(&src[*sourceLen - 8]);
if (crc32 != tinf_crc32(dst, dlen)) {
return TINF_DATA_ERROR;
}
return TINF_OK;
}
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