ref: bbc4d770cd2a771205f0f11cda3e4839edbbe171
dir: /3rd/brieflz/depacks.c/
/*
* BriefLZ - small fast Lempel-Ziv
*
* C safe depacker
*
* Copyright (c) 2002-2018 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 "brieflz.h"
/* Internal data structure */
struct blz_state {
const unsigned char *src;
unsigned char *dst;
unsigned long src_avail;
unsigned long dst_avail;
unsigned int tag;
int bits_left;
};
#if !defined(BLZ_NO_LUT)
static const unsigned char blz_gamma_lookup[256][2] = {
/* 00xxxxxx = 2 */
{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2},
{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2},
{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2},
{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2},
{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2},
{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2},
{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2},
{2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2}, {2, 2},
/* 0100xxxx = 4 */
{4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4},
{4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4}, {4, 4},
/* 010100xx = 8 */
{8, 6}, {8, 6}, {8, 6}, {8, 6},
/* 01010100 = 16 01010101 = 16+ 01010110 = 17 01010111 = 17+ */
{16, 8}, {16, 0}, {17, 8}, {17, 0},
/* 010110xx = 9 */
{9, 6}, {9, 6}, {9, 6}, {9, 6},
/* 01011100 = 18 01011101 = 18+ 01011110 = 19 01011111 = 19+ */
{18, 8}, {18, 0}, {19, 8}, {19, 0},
/* 0110xxxx = 5 */
{5, 4}, {5, 4}, {5, 4}, {5, 4}, {5, 4}, {5, 4}, {5, 4}, {5, 4},
{5, 4}, {5, 4}, {5, 4}, {5, 4}, {5, 4}, {5, 4}, {5, 4}, {5, 4},
/* 011100xx = 10 */
{10, 6}, {10, 6}, {10, 6}, {10, 6},
/* 01110100 = 20 01110101 = 20+ 01110110 = 21 01110111 = 21+ */
{20, 8}, {20, 0}, {21, 8}, {21, 0},
/* 011110xx = 11 */
{11, 6}, {11, 6}, {11, 6}, {11, 6},
/* 01111100 = 22 01111101 = 22+ 01111110 = 23 01111111 = 23+ */
{22, 8}, {22, 0}, {23, 8}, {23, 0},
/* 10xxxxxx = 3 */
{3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2},
{3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2},
{3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2},
{3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2},
{3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2},
{3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2},
{3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2},
{3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2}, {3, 2},
/* 1100xxxx = 6 */
{6, 4}, {6, 4}, {6, 4}, {6, 4}, {6, 4}, {6, 4}, {6, 4}, {6, 4},
{6, 4}, {6, 4}, {6, 4}, {6, 4}, {6, 4}, {6, 4}, {6, 4}, {6, 4},
/* 110100xx = 12 */
{12, 6}, {12, 6}, {12, 6}, {12, 6},
/* 11010100 = 24 11010101 = 24+ 11010110 = 25 11010111 = 25+ */
{24, 8}, {24, 0}, {25, 8}, {25, 0},
/* 110110xx = 13 */
{13, 6}, {13, 6}, {13, 6}, {13, 6},
/* 11011100 = 26 11011101 = 26+ 11011110 = 27 11011111 = 27+ */
{26, 8}, {26, 0}, {27, 8}, {27, 0},
/* 1110xxxx = 7 */
{7, 4}, {7, 4}, {7, 4}, {7, 4}, {7, 4}, {7, 4}, {7, 4}, {7, 4},
{7, 4}, {7, 4}, {7, 4}, {7, 4}, {7, 4}, {7, 4}, {7, 4}, {7, 4},
/* 111100xx = 14 */
{14, 6}, {14, 6}, {14, 6}, {14, 6},
/* 11110100 = 28 11110101 = 28+ 11110110 = 29 11110111 = 29+ */
{28, 8}, {28, 0}, {29, 8}, {29, 0},
/* 111110xx = 15 */
{15, 6}, {15, 6}, {15, 6}, {15, 6},
/* 11111100 = 30 11111101 = 30+ 11111110 = 31 11111111 = 31+ */
{30, 8}, {30, 0}, {31, 8}, {31, 0}
};
#endif
static int
blz_getbit_safe(struct blz_state *bs, unsigned int *result)
{
unsigned int bit;
/* Check if tag is empty */
if (!bs->bits_left--) {
if (bs->src_avail < 2) {
return 0;
}
bs->src_avail -= 2;
/* Load next tag */
bs->tag = (unsigned int) bs->src[0]
| ((unsigned int) bs->src[1] << 8);
bs->src += 2;
bs->bits_left = 15;
}
/* Shift bit out of tag */
bit = (bs->tag & 0x8000) ? 1 : 0;
bs->tag <<= 1;
*result = bit;
return 1;
}
static int
blz_getgamma_safe(struct blz_state *bs, unsigned long *result)
{
unsigned int bit;
unsigned long v = 1;
#if !defined(BLZ_NO_LUT)
/* Decode up to 8 bits of gamma2 code using lookup if possible */
if (bs->bits_left >= 8) {
unsigned int top8 = (bs->tag >> 8) & 0x00FF;
int shift;
v = blz_gamma_lookup[top8][0];
shift = (int) blz_gamma_lookup[top8][1];
if (shift) {
bs->tag <<= shift;
bs->bits_left -= shift;
*result = v;
return 1;
}
bs->tag <<= 8;
bs->bits_left -= 8;
}
#endif
/* Input gamma2-encoded bits */
do {
if (!blz_getbit_safe(bs, &bit)) {
return 0;
}
if (v & 0x80000000UL) {
return 0;
}
v = (v << 1) + bit;
if (!blz_getbit_safe(bs, &bit)) {
return 0;
}
} while (bit);
*result = v;
return 1;
}
unsigned long
blz_depack_safe(const void *src, unsigned long src_size,
void *dst, unsigned long depacked_size)
{
struct blz_state bs;
unsigned long dst_size = 0;
unsigned int bit;
bs.src = (const unsigned char *) src;
bs.src_avail = src_size;
bs.dst = (unsigned char *) dst;
bs.dst_avail = depacked_size;
/* Initialise to one bit left in tag; that bit is zero (a literal) */
bs.bits_left = 1;
bs.tag = 0;
/* Main decompression loop */
while (dst_size < depacked_size) {
if (!blz_getbit_safe(&bs, &bit)) {
return BLZ_ERROR;
}
if (bit) {
unsigned long len;
unsigned long off;
/* Input match length and offset */
if (!blz_getgamma_safe(&bs, &len)) {
return BLZ_ERROR;
}
if (!blz_getgamma_safe(&bs, &off)) {
return BLZ_ERROR;
}
len += 2;
off -= 2;
if (off >= 0x00FFFFFFUL) {
return BLZ_ERROR;
}
if (!bs.src_avail--) {
return BLZ_ERROR;
}
off = (off << 8) + (unsigned long) *bs.src++ + 1;
if (off > depacked_size - bs.dst_avail) {
return BLZ_ERROR;
}
if (len > bs.dst_avail) {
return BLZ_ERROR;
}
bs.dst_avail -= len;
/* Copy match */
{
const unsigned char *p = bs.dst - off;
unsigned long i;
for (i = len; i > 0; --i) {
*bs.dst++ = *p++;
}
}
dst_size += len;
}
else {
/* Copy literal */
if (!bs.src_avail-- || !bs.dst_avail--) {
return BLZ_ERROR;
}
*bs.dst++ = *bs.src++;
dst_size++;
}
}
/* Return decompressed size */
return dst_size;
}
/* clang -g -O1 -fsanitize=fuzzer,address -DBLZ_FUZZING depacks.c */
#if defined(BLZ_FUZZING)
#include <limits.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
extern int
LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
if (size > ULONG_MAX / 2) { return 0; }
void *depacked = malloc(4096);
if (!depacked) { abort(); }
blz_depack_safe(data, size, depacked, 4096);
free(depacked);
return 0;
}
#endif