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linux/lib/lz4/lz4_decompress.c

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/*
* LZ4 - Fast LZ compression algorithm
* Copyright (C) 2011 - 2016, Yann Collet.
* BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
* You can contact the author at :
* - LZ4 homepage : http://www.lz4.org
* - LZ4 source repository : https://github.com/lz4/lz4
*
* Changed for kernel usage by:
* Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
*/
/*-************************************
* Dependencies
**************************************/
#include <linux/lz4.h>
#include "lz4defs.h"
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <asm/unaligned.h>
/*-*****************************
* Decompression functions
*******************************/
#define DEBUGLOG(l, ...) {} /* disabled */
#ifndef assert
#define assert(condition) ((void)0)
#endif
/*
* LZ4_decompress_generic() :
* This generic decompression function covers all use cases.
* It shall be instantiated several times, using different sets of directives.
* Note that it is important for performance that this function really get inlined,
* in order to remove useless branches during compilation optimization.
*/
static FORCE_INLINE int LZ4_decompress_generic(
const char * const src,
char * const dst,
int srcSize,
/*
* If endOnInput == endOnInputSize,
* this value is `dstCapacity`
*/
int outputSize,
/* endOnOutputSize, endOnInputSize */
endCondition_directive endOnInput,
/* full, partial */
earlyEnd_directive partialDecoding,
/* noDict, withPrefix64k, usingExtDict */
dict_directive dict,
/* always <= dst, == dst when no prefix */
const BYTE * const lowPrefix,
/* only if dict == usingExtDict */
const BYTE * const dictStart,
/* note : = 0 if noDict */
const size_t dictSize
)
{
const BYTE *ip = (const BYTE *) src;
const BYTE * const iend = ip + srcSize;
BYTE *op = (BYTE *) dst;
BYTE * const oend = op + outputSize;
BYTE *cpy;
const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize;
static const unsigned int inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4};
static const int dec64table[8] = {0, 0, 0, -1, -4, 1, 2, 3};
const int safeDecode = (endOnInput == endOnInputSize);
const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB)));
/* Set up the "end" pointers for the shortcut. */
const BYTE *const shortiend = iend -
(endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/;
const BYTE *const shortoend = oend -
(endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/;
DEBUGLOG(5, "%s (srcSize:%i, dstSize:%i)", __func__,
srcSize, outputSize);
/* Special cases */
assert(lowPrefix <= op);
assert(src != NULL);
/* Empty output buffer */
if ((endOnInput) && (unlikely(outputSize == 0)))
return ((srcSize == 1) && (*ip == 0)) ? 0 : -1;
if ((!endOnInput) && (unlikely(outputSize == 0)))
return (*ip == 0 ? 1 : -1);
if ((endOnInput) && unlikely(srcSize == 0))
return -1;
/* Main Loop : decode sequences */
while (1) {
size_t length;
const BYTE *match;
size_t offset;
/* get literal length */
unsigned int const token = *ip++;
length = token>>ML_BITS;
/* ip < iend before the increment */
assert(!endOnInput || ip <= iend);
/*
* A two-stage shortcut for the most common case:
* 1) If the literal length is 0..14, and there is enough
* space, enter the shortcut and copy 16 bytes on behalf
* of the literals (in the fast mode, only 8 bytes can be
* safely copied this way).
* 2) Further if the match length is 4..18, copy 18 bytes
* in a similar manner; but we ensure that there's enough
* space in the output for those 18 bytes earlier, upon
* entering the shortcut (in other words, there is a
* combined check for both stages).
*
* The & in the likely() below is intentionally not && so that
* some compilers can produce better parallelized runtime code
*/
if ((endOnInput ? length != RUN_MASK : length <= 8)
/*
* strictly "less than" on input, to re-enter
* the loop with at least one byte
*/
&& likely((endOnInput ? ip < shortiend : 1) &
(op <= shortoend))) {
/* Copy the literals */
memcpy(op, ip, endOnInput ? 16 : 8);
op += length; ip += length;
/*
* The second stage:
* prepare for match copying, decode full info.
* If it doesn't work out, the info won't be wasted.
*/
length = token & ML_MASK; /* match length */
offset = LZ4_readLE16(ip);
ip += 2;
match = op - offset;
assert(match <= op); /* check overflow */
/* Do not deal with overlapping matches. */
if ((length != ML_MASK) &&
(offset >= 8) &&
(dict == withPrefix64k || match >= lowPrefix)) {
/* Copy the match. */
memcpy(op + 0, match + 0, 8);
memcpy(op + 8, match + 8, 8);
memcpy(op + 16, match + 16, 2);
op += length + MINMATCH;
/* Both stages worked, load the next token. */
continue;
}
/*
* The second stage didn't work out, but the info
* is ready. Propel it right to the point of match
* copying.
*/
goto _copy_match;
}
/* decode literal length */
if (length == RUN_MASK) {
unsigned int s;
if (unlikely(endOnInput ? ip >= iend - RUN_MASK : 0)) {
/* overflow detection */
goto _output_error;
}
do {
s = *ip++;
length += s;
} while (likely(endOnInput
? ip < iend - RUN_MASK
: 1) & (s == 255));
if ((safeDecode)
&& unlikely((uptrval)(op) +
length < (uptrval)(op))) {
/* overflow detection */
goto _output_error;
}
if ((safeDecode)
&& unlikely((uptrval)(ip) +
length < (uptrval)(ip))) {
/* overflow detection */
goto _output_error;
}
}
/* copy literals */
cpy = op + length;
LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH);
if (((endOnInput) && ((cpy > oend - MFLIMIT)
|| (ip + length > iend - (2 + 1 + LASTLITERALS))))
|| ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) {
if (partialDecoding) {
if (cpy > oend) {
/*
* Partial decoding :
* stop in the middle of literal segment
*/
cpy = oend;
length = oend - op;
}
if ((endOnInput)
&& (ip + length > iend)) {
/*
* Error :
* read attempt beyond
* end of input buffer
*/
goto _output_error;
}
} else {
if ((!endOnInput)
&& (cpy != oend)) {
/*
* Error :
* block decoding must
* stop exactly there
*/
goto _output_error;
}
if ((endOnInput)
&& ((ip + length != iend)
|| (cpy > oend))) {
/*
* Error :
* input must be consumed
*/
goto _output_error;
}
}
memcpy(op, ip, length);
ip += length;
op += length;
/* Necessarily EOF, due to parsing restrictions */
if (!partialDecoding || (cpy == oend))
break;
} else {
/* may overwrite up to WILDCOPYLENGTH beyond cpy */
LZ4_wildCopy(op, ip, cpy);
ip += length;
op = cpy;
}
/* get offset */
offset = LZ4_readLE16(ip);
ip += 2;
match = op - offset;
/* get matchlength */
length = token & ML_MASK;
_copy_match:
if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) {
/* Error : offset outside buffers */
goto _output_error;
}
/* costs ~1%; silence an msan warning when offset == 0 */
/*
* note : when partialDecoding, there is no guarantee that
* at least 4 bytes remain available in output buffer
*/
if (!partialDecoding) {
assert(oend > op);
assert(oend - op >= 4);
LZ4_write32(op, (U32)offset);
}
if (length == ML_MASK) {
unsigned int s;
do {
s = *ip++;
if ((endOnInput) && (ip > iend - LASTLITERALS))
goto _output_error;
length += s;
} while (s == 255);
if ((safeDecode)
&& unlikely(
(uptrval)(op) + length < (uptrval)op)) {
/* overflow detection */
goto _output_error;
}
}
length += MINMATCH;
/* match starting within external dictionary */
if ((dict == usingExtDict) && (match < lowPrefix)) {
if (unlikely(op + length > oend - LASTLITERALS)) {
/* doesn't respect parsing restriction */
if (!partialDecoding)
goto _output_error;
length = min(length, (size_t)(oend - op));
}
if (length <= (size_t)(lowPrefix - match)) {
/*
* match fits entirely within external
* dictionary : just copy
*/
memmove(op, dictEnd - (lowPrefix - match),
length);
op += length;
} else {
/*
* match stretches into both external
* dictionary and current block
*/
size_t const copySize = (size_t)(lowPrefix - match);
size_t const restSize = length - copySize;
memcpy(op, dictEnd - copySize, copySize);
op += copySize;
if (restSize > (size_t)(op - lowPrefix)) {
/* overlap copy */
BYTE * const endOfMatch = op + restSize;
const BYTE *copyFrom = lowPrefix;
while (op < endOfMatch)
*op++ = *copyFrom++;
} else {
memcpy(op, lowPrefix, restSize);
op += restSize;
}
}
continue;
}
/* copy match within block */
cpy = op + length;
/*
* partialDecoding :
* may not respect endBlock parsing restrictions
*/
assert(op <= oend);
if (partialDecoding &&
(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
size_t const mlen = min(length, (size_t)(oend - op));
const BYTE * const matchEnd = match + mlen;
BYTE * const copyEnd = op + mlen;
if (matchEnd > op) {
/* overlap copy */
while (op < copyEnd)
*op++ = *match++;
} else {
memcpy(op, match, mlen);
}
op = copyEnd;
if (op == oend)
break;
continue;
}
if (unlikely(offset < 8)) {
op[0] = match[0];
op[1] = match[1];
op[2] = match[2];
op[3] = match[3];
match += inc32table[offset];
memcpy(op + 4, match, 4);
match -= dec64table[offset];
} else {
LZ4_copy8(op, match);
match += 8;
}
op += 8;
if (unlikely(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
if (cpy > oend - LASTLITERALS) {
/*
* Error : last LASTLITERALS bytes
* must be literals (uncompressed)
*/
goto _output_error;
}
if (op < oCopyLimit) {
LZ4_wildCopy(op, match, oCopyLimit);
match += oCopyLimit - op;
op = oCopyLimit;
}
while (op < cpy)
*op++ = *match++;
} else {
LZ4_copy8(op, match);
if (length > 16)
LZ4_wildCopy(op + 8, match + 8, cpy);
}
op = cpy; /* wildcopy correction */
}
/* end of decoding */
if (endOnInput) {
/* Nb of output bytes decoded */
return (int) (((char *)op) - dst);
} else {
/* Nb of input bytes read */
return (int) (((const char *)ip) - src);
}
/* Overflow error detected */
_output_error:
return (int) (-(((const char *)ip) - src)) - 1;
}
int LZ4_decompress_safe(const char *source, char *dest,
int compressedSize, int maxDecompressedSize)
{
return LZ4_decompress_generic(source, dest,
compressedSize, maxDecompressedSize,
endOnInputSize, decode_full_block,
noDict, (BYTE *)dest, NULL, 0);
}
int LZ4_decompress_safe_partial(const char *src, char *dst,
int compressedSize, int targetOutputSize, int dstCapacity)
{
dstCapacity = min(targetOutputSize, dstCapacity);
return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity,
endOnInputSize, partial_decode,
noDict, (BYTE *)dst, NULL, 0);
}
int LZ4_decompress_fast(const char *source, char *dest, int originalSize)
{
return LZ4_decompress_generic(source, dest, 0, originalSize,
endOnOutputSize, decode_full_block,
withPrefix64k,
(BYTE *)dest - 64 * KB, NULL, 0);
}
/* ===== Instantiate a few more decoding cases, used more than once. ===== */
int LZ4_decompress_safe_withPrefix64k(const char *source, char *dest,
int compressedSize, int maxOutputSize)
{
return LZ4_decompress_generic(source, dest,
compressedSize, maxOutputSize,
endOnInputSize, decode_full_block,
withPrefix64k,
(BYTE *)dest - 64 * KB, NULL, 0);
}
static int LZ4_decompress_safe_withSmallPrefix(const char *source, char *dest,
int compressedSize,
int maxOutputSize,
size_t prefixSize)
{
return LZ4_decompress_generic(source, dest,
compressedSize, maxOutputSize,
endOnInputSize, decode_full_block,
noDict,
(BYTE *)dest - prefixSize, NULL, 0);
}
int LZ4_decompress_safe_forceExtDict(const char *source, char *dest,
int compressedSize, int maxOutputSize,
const void *dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest,
compressedSize, maxOutputSize,
endOnInputSize, decode_full_block,
usingExtDict, (BYTE *)dest,
(const BYTE *)dictStart, dictSize);
}
static int LZ4_decompress_fast_extDict(const char *source, char *dest,
int originalSize,
const void *dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest,
0, originalSize,
endOnOutputSize, decode_full_block,
usingExtDict, (BYTE *)dest,
(const BYTE *)dictStart, dictSize);
}
/*
* The "double dictionary" mode, for use with e.g. ring buffers: the first part
* of the dictionary is passed as prefix, and the second via dictStart + dictSize.
* These routines are used only once, in LZ4_decompress_*_continue().
*/
static FORCE_INLINE
int LZ4_decompress_safe_doubleDict(const char *source, char *dest,
int compressedSize, int maxOutputSize,
size_t prefixSize,
const void *dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest,
compressedSize, maxOutputSize,
endOnInputSize, decode_full_block,
usingExtDict, (BYTE *)dest - prefixSize,
(const BYTE *)dictStart, dictSize);
}
static FORCE_INLINE
int LZ4_decompress_fast_doubleDict(const char *source, char *dest,
int originalSize, size_t prefixSize,
const void *dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest,
0, originalSize,
endOnOutputSize, decode_full_block,
usingExtDict, (BYTE *)dest - prefixSize,
(const BYTE *)dictStart, dictSize);
}
/* ===== streaming decompression functions ===== */
int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
const char *dictionary, int dictSize)
{
LZ4_streamDecode_t_internal *lz4sd =
&LZ4_streamDecode->internal_donotuse;
lz4sd->prefixSize = (size_t) dictSize;
lz4sd->prefixEnd = (const BYTE *) dictionary + dictSize;
lz4sd->externalDict = NULL;
lz4sd->extDictSize = 0;
return 1;
}
/*
* *_continue() :
* These decoding functions allow decompression of multiple blocks
* in "streaming" mode.
* Previously decoded blocks must still be available at the memory
* position where they were decoded.
* If it's not possible, save the relevant part of
* decoded data into a safe buffer,
* and indicate where it stands using LZ4_setStreamDecode()
*/
int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
const char *source, char *dest, int compressedSize, int maxOutputSize)
{
LZ4_streamDecode_t_internal *lz4sd =
&LZ4_streamDecode->internal_donotuse;
int result;
if (lz4sd->prefixSize == 0) {
/* The first call, no dictionary yet. */
assert(lz4sd->extDictSize == 0);
result = LZ4_decompress_safe(source, dest,
compressedSize, maxOutputSize);
if (result <= 0)
return result;
lz4sd->prefixSize = result;
lz4sd->prefixEnd = (BYTE *)dest + result;
} else if (lz4sd->prefixEnd == (BYTE *)dest) {
/* They're rolling the current segment. */
if (lz4sd->prefixSize >= 64 * KB - 1)
result = LZ4_decompress_safe_withPrefix64k(source, dest,
compressedSize, maxOutputSize);
else if (lz4sd->extDictSize == 0)
result = LZ4_decompress_safe_withSmallPrefix(source,
dest, compressedSize, maxOutputSize,
lz4sd->prefixSize);
else
result = LZ4_decompress_safe_doubleDict(source, dest,
compressedSize, maxOutputSize,
lz4sd->prefixSize,
lz4sd->externalDict, lz4sd->extDictSize);
if (result <= 0)
return result;
lz4sd->prefixSize += result;
lz4sd->prefixEnd += result;
} else {
/*
* The buffer wraps around, or they're
* switching to another buffer.
*/
lz4sd->extDictSize = lz4sd->prefixSize;
lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
result = LZ4_decompress_safe_forceExtDict(source, dest,
compressedSize, maxOutputSize,
lz4sd->externalDict, lz4sd->extDictSize);
if (result <= 0)
return result;
lz4sd->prefixSize = result;
lz4sd->prefixEnd = (BYTE *)dest + result;
}
return result;
}
int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
const char *source, char *dest, int originalSize)
{
LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
int result;
if (lz4sd->prefixSize == 0) {
assert(lz4sd->extDictSize == 0);
result = LZ4_decompress_fast(source, dest, originalSize);
if (result <= 0)
return result;
lz4sd->prefixSize = originalSize;
lz4sd->prefixEnd = (BYTE *)dest + originalSize;
} else if (lz4sd->prefixEnd == (BYTE *)dest) {
if (lz4sd->prefixSize >= 64 * KB - 1 ||
lz4sd->extDictSize == 0)
result = LZ4_decompress_fast(source, dest,
originalSize);
else
result = LZ4_decompress_fast_doubleDict(source, dest,
originalSize, lz4sd->prefixSize,
lz4sd->externalDict, lz4sd->extDictSize);
if (result <= 0)
return result;
lz4sd->prefixSize += originalSize;
lz4sd->prefixEnd += originalSize;
} else {
lz4sd->extDictSize = lz4sd->prefixSize;
lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
result = LZ4_decompress_fast_extDict(source, dest,
originalSize, lz4sd->externalDict, lz4sd->extDictSize);
if (result <= 0)
return result;
lz4sd->prefixSize = originalSize;
lz4sd->prefixEnd = (BYTE *)dest + originalSize;
}
return result;
}
int LZ4_decompress_safe_usingDict(const char *source, char *dest,
int compressedSize, int maxOutputSize,
const char *dictStart, int dictSize)
{
if (dictSize == 0)
return LZ4_decompress_safe(source, dest,
compressedSize, maxOutputSize);
if (dictStart+dictSize == dest) {
if (dictSize >= 64 * KB - 1)
return LZ4_decompress_safe_withPrefix64k(source, dest,
compressedSize, maxOutputSize);
return LZ4_decompress_safe_withSmallPrefix(source, dest,
compressedSize, maxOutputSize, dictSize);
}
return LZ4_decompress_safe_forceExtDict(source, dest,
compressedSize, maxOutputSize, dictStart, dictSize);
}
int LZ4_decompress_fast_usingDict(const char *source, char *dest,
int originalSize,
const char *dictStart, int dictSize)
{
if (dictSize == 0 || dictStart + dictSize == dest)
return LZ4_decompress_fast(source, dest, originalSize);
return LZ4_decompress_fast_extDict(source, dest, originalSize,
dictStart, dictSize);
}
#ifndef STATIC
EXPORT_SYMBOL(LZ4_decompress_safe);
EXPORT_SYMBOL(LZ4_decompress_safe_partial);
EXPORT_SYMBOL(LZ4_decompress_fast);
EXPORT_SYMBOL(LZ4_setStreamDecode);
EXPORT_SYMBOL(LZ4_decompress_safe_continue);
EXPORT_SYMBOL(LZ4_decompress_fast_continue);
EXPORT_SYMBOL(LZ4_decompress_safe_usingDict);
EXPORT_SYMBOL(LZ4_decompress_fast_usingDict);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION("LZ4 decompressor");
#endif
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