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zstd_decompress.c
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zstd_decompress.c
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/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
* You may select, at your option, one of the above-listed licenses.
*/
/* ***************************************************************
* Tuning parameters
*****************************************************************/
/*!
* HEAPMODE :
* Select how default decompression function ZSTD_decompress() allocates its context,
* on stack (0), or into heap (1, default; requires malloc()).
* Note that functions with explicit context such as ZSTD_decompressDCtx() are unaffected.
*/
#ifndef ZSTD_HEAPMODE
# define ZSTD_HEAPMODE 1
#endif
/*!
* LEGACY_SUPPORT :
* if set to 1+, ZSTD_decompress() can decode older formats (v0.1+)
*/
#ifndef ZSTD_LEGACY_SUPPORT
# define ZSTD_LEGACY_SUPPORT 0
#endif
/*!
* MAXWINDOWSIZE_DEFAULT :
* maximum window size accepted by DStream __by default__.
* Frames requiring more memory will be rejected.
* It's possible to set a different limit using ZSTD_DCtx_setMaxWindowSize().
*/
#ifndef ZSTD_MAXWINDOWSIZE_DEFAULT
# define ZSTD_MAXWINDOWSIZE_DEFAULT (((U32)1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT) + 1)
#endif
/*!
* NO_FORWARD_PROGRESS_MAX :
* maximum allowed nb of calls to ZSTD_decompressStream()
* without any forward progress
* (defined as: no byte read from input, and no byte flushed to output)
* before triggering an error.
*/
#ifndef ZSTD_NO_FORWARD_PROGRESS_MAX
# define ZSTD_NO_FORWARD_PROGRESS_MAX 16
#endif
/*-*******************************************************
* Dependencies
*********************************************************/
#include "../common/zstd_deps.h" /* ZSTD_memcpy, ZSTD_memmove, ZSTD_memset */
#include "../common/allocations.h" /* ZSTD_customMalloc, ZSTD_customCalloc, ZSTD_customFree */
#include "../common/error_private.h"
#include "../common/zstd_internal.h" /* blockProperties_t */
#include "../common/mem.h" /* low level memory routines */
#include "../common/bits.h" /* ZSTD_highbit32 */
#define FSE_STATIC_LINKING_ONLY
#include "../common/fse.h"
#include "../common/huf.h"
#include "../common/xxhash.h" /* XXH64_reset, XXH64_update, XXH64_digest, XXH64 */
#include "zstd_decompress_internal.h" /* ZSTD_DCtx */
#include "zstd_ddict.h" /* ZSTD_DDictDictContent */
#include "zstd_decompress_block.h" /* ZSTD_decompressBlock_internal */
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
# include "../legacy/zstd_legacy.h"
#endif
/*************************************
* Multiple DDicts Hashset internals *
*************************************/
#define DDICT_HASHSET_MAX_LOAD_FACTOR_COUNT_MULT 4
#define DDICT_HASHSET_MAX_LOAD_FACTOR_SIZE_MULT 3 /* These two constants represent SIZE_MULT/COUNT_MULT load factor without using a float.
* Currently, that means a 0.75 load factor.
* So, if count * COUNT_MULT / size * SIZE_MULT != 0, then we've exceeded
* the load factor of the ddict hash set.
*/
#define DDICT_HASHSET_TABLE_BASE_SIZE 64
#define DDICT_HASHSET_RESIZE_FACTOR 2
/* Hash function to determine starting position of dict insertion within the table
* Returns an index between [0, hashSet->ddictPtrTableSize]
*/
static size_t ZSTD_DDictHashSet_getIndex(const ZSTD_DDictHashSet* hashSet, U32 dictID) {
const U64 hash = XXH64(&dictID, sizeof(U32), 0);
/* DDict ptr table size is a multiple of 2, use size - 1 as mask to get index within [0, hashSet->ddictPtrTableSize) */
return hash & (hashSet->ddictPtrTableSize - 1);
}
/* Adds DDict to a hashset without resizing it.
* If inserting a DDict with a dictID that already exists in the set, replaces the one in the set.
* Returns 0 if successful, or a zstd error code if something went wrong.
*/
static size_t ZSTD_DDictHashSet_emplaceDDict(ZSTD_DDictHashSet* hashSet, const ZSTD_DDict* ddict) {
const U32 dictID = ZSTD_getDictID_fromDDict(ddict);
size_t idx = ZSTD_DDictHashSet_getIndex(hashSet, dictID);
const size_t idxRangeMask = hashSet->ddictPtrTableSize - 1;
RETURN_ERROR_IF(hashSet->ddictPtrCount == hashSet->ddictPtrTableSize, GENERIC, "Hash set is full!");
DEBUGLOG(4, "Hashed index: for dictID: %u is %zu", dictID, idx);
while (hashSet->ddictPtrTable[idx] != NULL) {
/* Replace existing ddict if inserting ddict with same dictID */
if (ZSTD_getDictID_fromDDict(hashSet->ddictPtrTable[idx]) == dictID) {
DEBUGLOG(4, "DictID already exists, replacing rather than adding");
hashSet->ddictPtrTable[idx] = ddict;
return 0;
}
idx &= idxRangeMask;
idx++;
}
DEBUGLOG(4, "Final idx after probing for dictID %u is: %zu", dictID, idx);
hashSet->ddictPtrTable[idx] = ddict;
hashSet->ddictPtrCount++;
return 0;
}
/* Expands hash table by factor of DDICT_HASHSET_RESIZE_FACTOR and
* rehashes all values, allocates new table, frees old table.
* Returns 0 on success, otherwise a zstd error code.
*/
static size_t ZSTD_DDictHashSet_expand(ZSTD_DDictHashSet* hashSet, ZSTD_customMem customMem) {
size_t newTableSize = hashSet->ddictPtrTableSize * DDICT_HASHSET_RESIZE_FACTOR;
const ZSTD_DDict** newTable = (const ZSTD_DDict**)ZSTD_customCalloc(sizeof(ZSTD_DDict*) * newTableSize, customMem);
const ZSTD_DDict** oldTable = hashSet->ddictPtrTable;
size_t oldTableSize = hashSet->ddictPtrTableSize;
size_t i;
DEBUGLOG(4, "Expanding DDict hash table! Old size: %zu new size: %zu", oldTableSize, newTableSize);
RETURN_ERROR_IF(!newTable, memory_allocation, "Expanded hashset allocation failed!");
hashSet->ddictPtrTable = newTable;
hashSet->ddictPtrTableSize = newTableSize;
hashSet->ddictPtrCount = 0;
for (i = 0; i < oldTableSize; ++i) {
if (oldTable[i] != NULL) {
FORWARD_IF_ERROR(ZSTD_DDictHashSet_emplaceDDict(hashSet, oldTable[i]), "");
}
}
ZSTD_customFree((void*)oldTable, customMem);
DEBUGLOG(4, "Finished re-hash");
return 0;
}
/* Fetches a DDict with the given dictID
* Returns the ZSTD_DDict* with the requested dictID. If it doesn't exist, then returns NULL.
*/
static const ZSTD_DDict* ZSTD_DDictHashSet_getDDict(ZSTD_DDictHashSet* hashSet, U32 dictID) {
size_t idx = ZSTD_DDictHashSet_getIndex(hashSet, dictID);
const size_t idxRangeMask = hashSet->ddictPtrTableSize - 1;
DEBUGLOG(4, "Hashed index: for dictID: %u is %zu", dictID, idx);
for (;;) {
size_t currDictID = ZSTD_getDictID_fromDDict(hashSet->ddictPtrTable[idx]);
if (currDictID == dictID || currDictID == 0) {
/* currDictID == 0 implies a NULL ddict entry */
break;
} else {
idx &= idxRangeMask; /* Goes to start of table when we reach the end */
idx++;
}
}
DEBUGLOG(4, "Final idx after probing for dictID %u is: %zu", dictID, idx);
return hashSet->ddictPtrTable[idx];
}
/* Allocates space for and returns a ddict hash set
* The hash set's ZSTD_DDict* table has all values automatically set to NULL to begin with.
* Returns NULL if allocation failed.
*/
static ZSTD_DDictHashSet* ZSTD_createDDictHashSet(ZSTD_customMem customMem) {
ZSTD_DDictHashSet* ret = (ZSTD_DDictHashSet*)ZSTD_customMalloc(sizeof(ZSTD_DDictHashSet), customMem);
DEBUGLOG(4, "Allocating new hash set");
if (!ret)
return NULL;
ret->ddictPtrTable = (const ZSTD_DDict**)ZSTD_customCalloc(DDICT_HASHSET_TABLE_BASE_SIZE * sizeof(ZSTD_DDict*), customMem);
if (!ret->ddictPtrTable) {
ZSTD_customFree(ret, customMem);
return NULL;
}
ret->ddictPtrTableSize = DDICT_HASHSET_TABLE_BASE_SIZE;
ret->ddictPtrCount = 0;
return ret;
}
/* Frees the table of ZSTD_DDict* within a hashset, then frees the hashset itself.
* Note: The ZSTD_DDict* within the table are NOT freed.
*/
static void ZSTD_freeDDictHashSet(ZSTD_DDictHashSet* hashSet, ZSTD_customMem customMem) {
DEBUGLOG(4, "Freeing ddict hash set");
if (hashSet && hashSet->ddictPtrTable) {
ZSTD_customFree((void*)hashSet->ddictPtrTable, customMem);
}
if (hashSet) {
ZSTD_customFree(hashSet, customMem);
}
}
/* Public function: Adds a DDict into the ZSTD_DDictHashSet, possibly triggering a resize of the hash set.
* Returns 0 on success, or a ZSTD error.
*/
static size_t ZSTD_DDictHashSet_addDDict(ZSTD_DDictHashSet* hashSet, const ZSTD_DDict* ddict, ZSTD_customMem customMem) {
DEBUGLOG(4, "Adding dict ID: %u to hashset with - Count: %zu Tablesize: %zu", ZSTD_getDictID_fromDDict(ddict), hashSet->ddictPtrCount, hashSet->ddictPtrTableSize);
if (hashSet->ddictPtrCount * DDICT_HASHSET_MAX_LOAD_FACTOR_COUNT_MULT / hashSet->ddictPtrTableSize * DDICT_HASHSET_MAX_LOAD_FACTOR_SIZE_MULT != 0) {
FORWARD_IF_ERROR(ZSTD_DDictHashSet_expand(hashSet, customMem), "");
}
FORWARD_IF_ERROR(ZSTD_DDictHashSet_emplaceDDict(hashSet, ddict), "");
return 0;
}
/*-*************************************************************
* Context management
***************************************************************/
size_t ZSTD_sizeof_DCtx (const ZSTD_DCtx* dctx)
{
if (dctx==NULL) return 0; /* support sizeof NULL */
return sizeof(*dctx)
+ ZSTD_sizeof_DDict(dctx->ddictLocal)
+ dctx->inBuffSize + dctx->outBuffSize;
}
size_t ZSTD_estimateDCtxSize(void) { return sizeof(ZSTD_DCtx); }
static size_t ZSTD_startingInputLength(ZSTD_format_e format)
{
size_t const startingInputLength = ZSTD_FRAMEHEADERSIZE_PREFIX(format);
/* only supports formats ZSTD_f_zstd1 and ZSTD_f_zstd1_magicless */
assert( (format == ZSTD_f_zstd1) || (format == ZSTD_f_zstd1_magicless) );
return startingInputLength;
}
static void ZSTD_DCtx_resetParameters(ZSTD_DCtx* dctx)
{
assert(dctx->streamStage == zdss_init);
dctx->format = ZSTD_f_zstd1;
dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
dctx->outBufferMode = ZSTD_bm_buffered;
dctx->forceIgnoreChecksum = ZSTD_d_validateChecksum;
dctx->refMultipleDDicts = ZSTD_rmd_refSingleDDict;
dctx->disableHufAsm = 0;
dctx->maxBlockSizeParam = 0;
}
static void ZSTD_initDCtx_internal(ZSTD_DCtx* dctx)
{
dctx->staticSize = 0;
dctx->ddict = NULL;
dctx->ddictLocal = NULL;
dctx->dictEnd = NULL;
dctx->ddictIsCold = 0;
dctx->dictUses = ZSTD_dont_use;
dctx->inBuff = NULL;
dctx->inBuffSize = 0;
dctx->outBuffSize = 0;
dctx->streamStage = zdss_init;
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
dctx->legacyContext = NULL;
dctx->previousLegacyVersion = 0;
#endif
dctx->noForwardProgress = 0;
dctx->oversizedDuration = 0;
dctx->isFrameDecompression = 1;
#if DYNAMIC_BMI2
dctx->bmi2 = ZSTD_cpuSupportsBmi2();
#endif
dctx->ddictSet = NULL;
ZSTD_DCtx_resetParameters(dctx);
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
dctx->dictContentEndForFuzzing = NULL;
#endif
}
ZSTD_DCtx* ZSTD_initStaticDCtx(void *workspace, size_t workspaceSize)
{
ZSTD_DCtx* const dctx = (ZSTD_DCtx*) workspace;
if ((size_t)workspace & 7) return NULL; /* 8-aligned */
if (workspaceSize < sizeof(ZSTD_DCtx)) return NULL; /* minimum size */
ZSTD_initDCtx_internal(dctx);
dctx->staticSize = workspaceSize;
dctx->inBuff = (char*)(dctx+1);
return dctx;
}
static ZSTD_DCtx* ZSTD_createDCtx_internal(ZSTD_customMem customMem) {
if ((!customMem.customAlloc) ^ (!customMem.customFree)) return NULL;
{ ZSTD_DCtx* const dctx = (ZSTD_DCtx*)ZSTD_customMalloc(sizeof(*dctx), customMem);
if (!dctx) return NULL;
dctx->customMem = customMem;
ZSTD_initDCtx_internal(dctx);
return dctx;
}
}
ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem)
{
return ZSTD_createDCtx_internal(customMem);
}
ZSTD_DCtx* ZSTD_createDCtx(void)
{
DEBUGLOG(3, "ZSTD_createDCtx");
return ZSTD_createDCtx_internal(ZSTD_defaultCMem);
}
static void ZSTD_clearDict(ZSTD_DCtx* dctx)
{
ZSTD_freeDDict(dctx->ddictLocal);
dctx->ddictLocal = NULL;
dctx->ddict = NULL;
dctx->dictUses = ZSTD_dont_use;
}
size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx)
{
if (dctx==NULL) return 0; /* support free on NULL */
RETURN_ERROR_IF(dctx->staticSize, memory_allocation, "not compatible with static DCtx");
{ ZSTD_customMem const cMem = dctx->customMem;
ZSTD_clearDict(dctx);
ZSTD_customFree(dctx->inBuff, cMem);
dctx->inBuff = NULL;
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
if (dctx->legacyContext)
ZSTD_freeLegacyStreamContext(dctx->legacyContext, dctx->previousLegacyVersion);
#endif
if (dctx->ddictSet) {
ZSTD_freeDDictHashSet(dctx->ddictSet, cMem);
dctx->ddictSet = NULL;
}
ZSTD_customFree(dctx, cMem);
return 0;
}
}
/* no longer useful */
void ZSTD_copyDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx)
{
size_t const toCopy = (size_t)((char*)(&dstDCtx->inBuff) - (char*)dstDCtx);
ZSTD_memcpy(dstDCtx, srcDCtx, toCopy); /* no need to copy workspace */
}
/* Given a dctx with a digested frame params, re-selects the correct ZSTD_DDict based on
* the requested dict ID from the frame. If there exists a reference to the correct ZSTD_DDict, then
* accordingly sets the ddict to be used to decompress the frame.
*
* If no DDict is found, then no action is taken, and the ZSTD_DCtx::ddict remains as-is.
*
* ZSTD_d_refMultipleDDicts must be enabled for this function to be called.
*/
static void ZSTD_DCtx_selectFrameDDict(ZSTD_DCtx* dctx) {
assert(dctx->refMultipleDDicts && dctx->ddictSet);
DEBUGLOG(4, "Adjusting DDict based on requested dict ID from frame");
if (dctx->ddict) {
const ZSTD_DDict* frameDDict = ZSTD_DDictHashSet_getDDict(dctx->ddictSet, dctx->fParams.dictID);
if (frameDDict) {
DEBUGLOG(4, "DDict found!");
ZSTD_clearDict(dctx);
dctx->dictID = dctx->fParams.dictID;
dctx->ddict = frameDDict;
dctx->dictUses = ZSTD_use_indefinitely;
}
}
}
/*-*************************************************************
* Frame header decoding
***************************************************************/
/*! ZSTD_isFrame() :
* Tells if the content of `buffer` starts with a valid Frame Identifier.
* Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0.
* Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled.
* Note 3 : Skippable Frame Identifiers are considered valid. */
unsigned ZSTD_isFrame(const void* buffer, size_t size)
{
if (size < ZSTD_FRAMEIDSIZE) return 0;
{ U32 const magic = MEM_readLE32(buffer);
if (magic == ZSTD_MAGICNUMBER) return 1;
if ((magic & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) return 1;
}
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
if (ZSTD_isLegacy(buffer, size)) return 1;
#endif
return 0;
}
/*! ZSTD_isSkippableFrame() :
* Tells if the content of `buffer` starts with a valid Frame Identifier for a skippable frame.
* Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0.
*/
unsigned ZSTD_isSkippableFrame(const void* buffer, size_t size)
{
if (size < ZSTD_FRAMEIDSIZE) return 0;
{ U32 const magic = MEM_readLE32(buffer);
if ((magic & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) return 1;
}
return 0;
}
/** ZSTD_frameHeaderSize_internal() :
* srcSize must be large enough to reach header size fields.
* note : only works for formats ZSTD_f_zstd1 and ZSTD_f_zstd1_magicless.
* @return : size of the Frame Header
* or an error code, which can be tested with ZSTD_isError() */
static size_t ZSTD_frameHeaderSize_internal(const void* src, size_t srcSize, ZSTD_format_e format)
{
size_t const minInputSize = ZSTD_startingInputLength(format);
RETURN_ERROR_IF(srcSize < minInputSize, srcSize_wrong, "");
{ BYTE const fhd = ((const BYTE*)src)[minInputSize-1];
U32 const dictID= fhd & 3;
U32 const singleSegment = (fhd >> 5) & 1;
U32 const fcsId = fhd >> 6;
return minInputSize + !singleSegment
+ ZSTD_did_fieldSize[dictID] + ZSTD_fcs_fieldSize[fcsId]
+ (singleSegment && !fcsId);
}
}
/** ZSTD_frameHeaderSize() :
* srcSize must be >= ZSTD_frameHeaderSize_prefix.
* @return : size of the Frame Header,
* or an error code (if srcSize is too small) */
size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize)
{
return ZSTD_frameHeaderSize_internal(src, srcSize, ZSTD_f_zstd1);
}
/** ZSTD_getFrameHeader_advanced() :
* decode Frame Header, or require larger `srcSize`.
* note : only works for formats ZSTD_f_zstd1 and ZSTD_f_zstd1_magicless
* @return : 0, `zfhPtr` is correctly filled,
* >0, `srcSize` is too small, value is wanted `srcSize` amount,
** or an error code, which can be tested using ZSTD_isError() */
size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format)
{
const BYTE* ip = (const BYTE*)src;
size_t const minInputSize = ZSTD_startingInputLength(format);
DEBUGLOG(5, "ZSTD_getFrameHeader_advanced: minInputSize = %zu, srcSize = %zu", minInputSize, srcSize);
if (srcSize > 0) {
/* note : technically could be considered an assert(), since it's an invalid entry */
RETURN_ERROR_IF(src==NULL, GENERIC, "invalid parameter : src==NULL, but srcSize>0");
}
if (srcSize < minInputSize) {
if (srcSize > 0 && format != ZSTD_f_zstd1_magicless) {
/* when receiving less than @minInputSize bytes,
* control these bytes at least correspond to a supported magic number
* in order to error out early if they don't.
**/
size_t const toCopy = MIN(4, srcSize);
unsigned char hbuf[4]; MEM_writeLE32(hbuf, ZSTD_MAGICNUMBER);
assert(src != NULL);
ZSTD_memcpy(hbuf, src, toCopy);
if ( MEM_readLE32(hbuf) != ZSTD_MAGICNUMBER ) {
/* not a zstd frame : let's check if it's a skippable frame */
MEM_writeLE32(hbuf, ZSTD_MAGIC_SKIPPABLE_START);
ZSTD_memcpy(hbuf, src, toCopy);
if ((MEM_readLE32(hbuf) & ZSTD_MAGIC_SKIPPABLE_MASK) != ZSTD_MAGIC_SKIPPABLE_START) {
RETURN_ERROR(prefix_unknown,
"first bytes don't correspond to any supported magic number");
} } }
return minInputSize;
}
ZSTD_memset(zfhPtr, 0, sizeof(*zfhPtr)); /* not strictly necessary, but static analyzers may not understand that zfhPtr will be read only if return value is zero, since they are 2 different signals */
if ( (format != ZSTD_f_zstd1_magicless)
&& (MEM_readLE32(src) != ZSTD_MAGICNUMBER) ) {
if ((MEM_readLE32(src) & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {
/* skippable frame */
if (srcSize < ZSTD_SKIPPABLEHEADERSIZE)
return ZSTD_SKIPPABLEHEADERSIZE; /* magic number + frame length */
ZSTD_memset(zfhPtr, 0, sizeof(*zfhPtr));
zfhPtr->frameContentSize = MEM_readLE32((const char *)src + ZSTD_FRAMEIDSIZE);
zfhPtr->frameType = ZSTD_skippableFrame;
return 0;
}
RETURN_ERROR(prefix_unknown, "");
}
/* ensure there is enough `srcSize` to fully read/decode frame header */
{ size_t const fhsize = ZSTD_frameHeaderSize_internal(src, srcSize, format);
if (srcSize < fhsize) return fhsize;
zfhPtr->headerSize = (U32)fhsize;
}
{ BYTE const fhdByte = ip[minInputSize-1];
size_t pos = minInputSize;
U32 const dictIDSizeCode = fhdByte&3;
U32 const checksumFlag = (fhdByte>>2)&1;
U32 const singleSegment = (fhdByte>>5)&1;
U32 const fcsID = fhdByte>>6;
U64 windowSize = 0;
U32 dictID = 0;
U64 frameContentSize = ZSTD_CONTENTSIZE_UNKNOWN;
RETURN_ERROR_IF((fhdByte & 0x08) != 0, frameParameter_unsupported,
"reserved bits, must be zero");
if (!singleSegment) {
BYTE const wlByte = ip[pos++];
U32 const windowLog = (wlByte >> 3) + ZSTD_WINDOWLOG_ABSOLUTEMIN;
RETURN_ERROR_IF(windowLog > ZSTD_WINDOWLOG_MAX, frameParameter_windowTooLarge, "");
windowSize = (1ULL << windowLog);
windowSize += (windowSize >> 3) * (wlByte&7);
}
switch(dictIDSizeCode)
{
default:
assert(0); /* impossible */
ZSTD_FALLTHROUGH;
case 0 : break;
case 1 : dictID = ip[pos]; pos++; break;
case 2 : dictID = MEM_readLE16(ip+pos); pos+=2; break;
case 3 : dictID = MEM_readLE32(ip+pos); pos+=4; break;
}
switch(fcsID)
{
default:
assert(0); /* impossible */
ZSTD_FALLTHROUGH;
case 0 : if (singleSegment) frameContentSize = ip[pos]; break;
case 1 : frameContentSize = MEM_readLE16(ip+pos)+256; break;
case 2 : frameContentSize = MEM_readLE32(ip+pos); break;
case 3 : frameContentSize = MEM_readLE64(ip+pos); break;
}
if (singleSegment) windowSize = frameContentSize;
zfhPtr->frameType = ZSTD_frame;
zfhPtr->frameContentSize = frameContentSize;
zfhPtr->windowSize = windowSize;
zfhPtr->blockSizeMax = (unsigned) MIN(windowSize, ZSTD_BLOCKSIZE_MAX);
zfhPtr->dictID = dictID;
zfhPtr->checksumFlag = checksumFlag;
}
return 0;
}
/** ZSTD_getFrameHeader() :
* decode Frame Header, or require larger `srcSize`.
* note : this function does not consume input, it only reads it.
* @return : 0, `zfhPtr` is correctly filled,
* >0, `srcSize` is too small, value is wanted `srcSize` amount,
* or an error code, which can be tested using ZSTD_isError() */
size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize)
{
return ZSTD_getFrameHeader_advanced(zfhPtr, src, srcSize, ZSTD_f_zstd1);
}
/** ZSTD_getFrameContentSize() :
* compatible with legacy mode
* @return : decompressed size of the single frame pointed to be `src` if known, otherwise
* - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined
* - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small) */
unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
if (ZSTD_isLegacy(src, srcSize)) {
unsigned long long const ret = ZSTD_getDecompressedSize_legacy(src, srcSize);
return ret == 0 ? ZSTD_CONTENTSIZE_UNKNOWN : ret;
}
#endif
{ ZSTD_frameHeader zfh;
if (ZSTD_getFrameHeader(&zfh, src, srcSize) != 0)
return ZSTD_CONTENTSIZE_ERROR;
if (zfh.frameType == ZSTD_skippableFrame) {
return 0;
} else {
return zfh.frameContentSize;
} }
}
static size_t readSkippableFrameSize(void const* src, size_t srcSize)
{
size_t const skippableHeaderSize = ZSTD_SKIPPABLEHEADERSIZE;
U32 sizeU32;
RETURN_ERROR_IF(srcSize < ZSTD_SKIPPABLEHEADERSIZE, srcSize_wrong, "");
sizeU32 = MEM_readLE32((BYTE const*)src + ZSTD_FRAMEIDSIZE);
RETURN_ERROR_IF((U32)(sizeU32 + ZSTD_SKIPPABLEHEADERSIZE) < sizeU32,
frameParameter_unsupported, "");
{ size_t const skippableSize = skippableHeaderSize + sizeU32;
RETURN_ERROR_IF(skippableSize > srcSize, srcSize_wrong, "");
return skippableSize;
}
}
/*! ZSTD_readSkippableFrame() :
* Retrieves content of a skippable frame, and writes it to dst buffer.
*
* The parameter magicVariant will receive the magicVariant that was supplied when the frame was written,
* i.e. magicNumber - ZSTD_MAGIC_SKIPPABLE_START. This can be NULL if the caller is not interested
* in the magicVariant.
*
* Returns an error if destination buffer is not large enough, or if this is not a valid skippable frame.
*
* @return : number of bytes written or a ZSTD error.
*/
size_t ZSTD_readSkippableFrame(void* dst, size_t dstCapacity,
unsigned* magicVariant, /* optional, can be NULL */
const void* src, size_t srcSize)
{
RETURN_ERROR_IF(srcSize < ZSTD_SKIPPABLEHEADERSIZE, srcSize_wrong, "");
{ U32 const magicNumber = MEM_readLE32(src);
size_t skippableFrameSize = readSkippableFrameSize(src, srcSize);
size_t skippableContentSize = skippableFrameSize - ZSTD_SKIPPABLEHEADERSIZE;
/* check input validity */
RETURN_ERROR_IF(!ZSTD_isSkippableFrame(src, srcSize), frameParameter_unsupported, "");
RETURN_ERROR_IF(skippableFrameSize < ZSTD_SKIPPABLEHEADERSIZE || skippableFrameSize > srcSize, srcSize_wrong, "");
RETURN_ERROR_IF(skippableContentSize > dstCapacity, dstSize_tooSmall, "");
/* deliver payload */
if (skippableContentSize > 0 && dst != NULL)
ZSTD_memcpy(dst, (const BYTE *)src + ZSTD_SKIPPABLEHEADERSIZE, skippableContentSize);
if (magicVariant != NULL)
*magicVariant = magicNumber - ZSTD_MAGIC_SKIPPABLE_START;
return skippableContentSize;
}
}
/** ZSTD_findDecompressedSize() :
* `srcSize` must be the exact length of some number of ZSTD compressed and/or
* skippable frames
* note: compatible with legacy mode
* @return : decompressed size of the frames contained */
unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize)
{
unsigned long long totalDstSize = 0;
while (srcSize >= ZSTD_startingInputLength(ZSTD_f_zstd1)) {
U32 const magicNumber = MEM_readLE32(src);
if ((magicNumber & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {
size_t const skippableSize = readSkippableFrameSize(src, srcSize);
if (ZSTD_isError(skippableSize)) return ZSTD_CONTENTSIZE_ERROR;
assert(skippableSize <= srcSize);
src = (const BYTE *)src + skippableSize;
srcSize -= skippableSize;
continue;
}
{ unsigned long long const fcs = ZSTD_getFrameContentSize(src, srcSize);
if (fcs >= ZSTD_CONTENTSIZE_ERROR) return fcs;
if (totalDstSize + fcs < totalDstSize)
return ZSTD_CONTENTSIZE_ERROR; /* check for overflow */
totalDstSize += fcs;
}
/* skip to next frame */
{ size_t const frameSrcSize = ZSTD_findFrameCompressedSize(src, srcSize);
if (ZSTD_isError(frameSrcSize)) return ZSTD_CONTENTSIZE_ERROR;
assert(frameSrcSize <= srcSize);
src = (const BYTE *)src + frameSrcSize;
srcSize -= frameSrcSize;
}
} /* while (srcSize >= ZSTD_frameHeaderSize_prefix) */
if (srcSize) return ZSTD_CONTENTSIZE_ERROR;
return totalDstSize;
}
/** ZSTD_getDecompressedSize() :
* compatible with legacy mode
* @return : decompressed size if known, 0 otherwise
note : 0 can mean any of the following :
- frame content is empty
- decompressed size field is not present in frame header
- frame header unknown / not supported
- frame header not complete (`srcSize` too small) */
unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize)
{
unsigned long long const ret = ZSTD_getFrameContentSize(src, srcSize);
ZSTD_STATIC_ASSERT(ZSTD_CONTENTSIZE_ERROR < ZSTD_CONTENTSIZE_UNKNOWN);
return (ret >= ZSTD_CONTENTSIZE_ERROR) ? 0 : ret;
}
/** ZSTD_decodeFrameHeader() :
* `headerSize` must be the size provided by ZSTD_frameHeaderSize().
* If multiple DDict references are enabled, also will choose the correct DDict to use.
* @return : 0 if success, or an error code, which can be tested using ZSTD_isError() */
static size_t ZSTD_decodeFrameHeader(ZSTD_DCtx* dctx, const void* src, size_t headerSize)
{
size_t const result = ZSTD_getFrameHeader_advanced(&(dctx->fParams), src, headerSize, dctx->format);
if (ZSTD_isError(result)) return result; /* invalid header */
RETURN_ERROR_IF(result>0, srcSize_wrong, "headerSize too small");
/* Reference DDict requested by frame if dctx references multiple ddicts */
if (dctx->refMultipleDDicts == ZSTD_rmd_refMultipleDDicts && dctx->ddictSet) {
ZSTD_DCtx_selectFrameDDict(dctx);
}
#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
/* Skip the dictID check in fuzzing mode, because it makes the search
* harder.
*/
RETURN_ERROR_IF(dctx->fParams.dictID && (dctx->dictID != dctx->fParams.dictID),
dictionary_wrong, "");
#endif
dctx->validateChecksum = (dctx->fParams.checksumFlag && !dctx->forceIgnoreChecksum) ? 1 : 0;
if (dctx->validateChecksum) XXH64_reset(&dctx->xxhState, 0);
dctx->processedCSize += headerSize;
return 0;
}
static ZSTD_frameSizeInfo ZSTD_errorFrameSizeInfo(size_t ret)
{
ZSTD_frameSizeInfo frameSizeInfo;
frameSizeInfo.compressedSize = ret;
frameSizeInfo.decompressedBound = ZSTD_CONTENTSIZE_ERROR;
return frameSizeInfo;
}
static ZSTD_frameSizeInfo ZSTD_findFrameSizeInfo(const void* src, size_t srcSize)
{
ZSTD_frameSizeInfo frameSizeInfo;
ZSTD_memset(&frameSizeInfo, 0, sizeof(ZSTD_frameSizeInfo));
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
if (ZSTD_isLegacy(src, srcSize))
return ZSTD_findFrameSizeInfoLegacy(src, srcSize);
#endif
if ((srcSize >= ZSTD_SKIPPABLEHEADERSIZE)
&& (MEM_readLE32(src) & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {
frameSizeInfo.compressedSize = readSkippableFrameSize(src, srcSize);
assert(ZSTD_isError(frameSizeInfo.compressedSize) ||
frameSizeInfo.compressedSize <= srcSize);
return frameSizeInfo;
} else {
const BYTE* ip = (const BYTE*)src;
const BYTE* const ipstart = ip;
size_t remainingSize = srcSize;
size_t nbBlocks = 0;
ZSTD_frameHeader zfh;
/* Extract Frame Header */
{ size_t const ret = ZSTD_getFrameHeader(&zfh, src, srcSize);
if (ZSTD_isError(ret))
return ZSTD_errorFrameSizeInfo(ret);
if (ret > 0)
return ZSTD_errorFrameSizeInfo(ERROR(srcSize_wrong));
}
ip += zfh.headerSize;
remainingSize -= zfh.headerSize;
/* Iterate over each block */
while (1) {
blockProperties_t blockProperties;
size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSize, &blockProperties);
if (ZSTD_isError(cBlockSize))
return ZSTD_errorFrameSizeInfo(cBlockSize);
if (ZSTD_blockHeaderSize + cBlockSize > remainingSize)
return ZSTD_errorFrameSizeInfo(ERROR(srcSize_wrong));
ip += ZSTD_blockHeaderSize + cBlockSize;
remainingSize -= ZSTD_blockHeaderSize + cBlockSize;
nbBlocks++;
if (blockProperties.lastBlock) break;
}
/* Final frame content checksum */
if (zfh.checksumFlag) {
if (remainingSize < 4)
return ZSTD_errorFrameSizeInfo(ERROR(srcSize_wrong));
ip += 4;
}
frameSizeInfo.nbBlocks = nbBlocks;
frameSizeInfo.compressedSize = (size_t)(ip - ipstart);
frameSizeInfo.decompressedBound = (zfh.frameContentSize != ZSTD_CONTENTSIZE_UNKNOWN)
? zfh.frameContentSize
: (unsigned long long)nbBlocks * zfh.blockSizeMax;
return frameSizeInfo;
}
}
/** ZSTD_findFrameCompressedSize() :
* compatible with legacy mode
* `src` must point to the start of a ZSTD frame, ZSTD legacy frame, or skippable frame
* `srcSize` must be at least as large as the frame contained
* @return : the compressed size of the frame starting at `src` */
size_t ZSTD_findFrameCompressedSize(const void *src, size_t srcSize)
{
ZSTD_frameSizeInfo const frameSizeInfo = ZSTD_findFrameSizeInfo(src, srcSize);
return frameSizeInfo.compressedSize;
}
/** ZSTD_decompressBound() :
* compatible with legacy mode
* `src` must point to the start of a ZSTD frame or a skippeable frame
* `srcSize` must be at least as large as the frame contained
* @return : the maximum decompressed size of the compressed source
*/
unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize)
{
unsigned long long bound = 0;
/* Iterate over each frame */
while (srcSize > 0) {
ZSTD_frameSizeInfo const frameSizeInfo = ZSTD_findFrameSizeInfo(src, srcSize);
size_t const compressedSize = frameSizeInfo.compressedSize;
unsigned long long const decompressedBound = frameSizeInfo.decompressedBound;
if (ZSTD_isError(compressedSize) || decompressedBound == ZSTD_CONTENTSIZE_ERROR)
return ZSTD_CONTENTSIZE_ERROR;
assert(srcSize >= compressedSize);
src = (const BYTE*)src + compressedSize;
srcSize -= compressedSize;
bound += decompressedBound;
}
return bound;
}
size_t ZSTD_decompressionMargin(void const* src, size_t srcSize)
{
size_t margin = 0;
unsigned maxBlockSize = 0;
/* Iterate over each frame */
while (srcSize > 0) {
ZSTD_frameSizeInfo const frameSizeInfo = ZSTD_findFrameSizeInfo(src, srcSize);
size_t const compressedSize = frameSizeInfo.compressedSize;
unsigned long long const decompressedBound = frameSizeInfo.decompressedBound;
ZSTD_frameHeader zfh;
FORWARD_IF_ERROR(ZSTD_getFrameHeader(&zfh, src, srcSize), "");
if (ZSTD_isError(compressedSize) || decompressedBound == ZSTD_CONTENTSIZE_ERROR)
return ERROR(corruption_detected);
if (zfh.frameType == ZSTD_frame) {
/* Add the frame header to our margin */
margin += zfh.headerSize;
/* Add the checksum to our margin */
margin += zfh.checksumFlag ? 4 : 0;
/* Add 3 bytes per block */
margin += 3 * frameSizeInfo.nbBlocks;
/* Compute the max block size */
maxBlockSize = MAX(maxBlockSize, zfh.blockSizeMax);
} else {
assert(zfh.frameType == ZSTD_skippableFrame);
/* Add the entire skippable frame size to our margin. */
margin += compressedSize;
}
assert(srcSize >= compressedSize);
src = (const BYTE*)src + compressedSize;
srcSize -= compressedSize;
}
/* Add the max block size back to the margin. */
margin += maxBlockSize;
return margin;
}
/*-*************************************************************
* Frame decoding
***************************************************************/
/** ZSTD_insertBlock() :
* insert `src` block into `dctx` history. Useful to track uncompressed blocks. */
size_t ZSTD_insertBlock(ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize)
{
DEBUGLOG(5, "ZSTD_insertBlock: %u bytes", (unsigned)blockSize);
ZSTD_checkContinuity(dctx, blockStart, blockSize);
dctx->previousDstEnd = (const char*)blockStart + blockSize;
return blockSize;
}
static size_t ZSTD_copyRawBlock(void* dst, size_t dstCapacity,
const void* src, size_t srcSize)
{
DEBUGLOG(5, "ZSTD_copyRawBlock");
RETURN_ERROR_IF(srcSize > dstCapacity, dstSize_tooSmall, "");
if (dst == NULL) {
if (srcSize == 0) return 0;
RETURN_ERROR(dstBuffer_null, "");
}
ZSTD_memmove(dst, src, srcSize);
return srcSize;
}
static size_t ZSTD_setRleBlock(void* dst, size_t dstCapacity,
BYTE b,
size_t regenSize)
{
RETURN_ERROR_IF(regenSize > dstCapacity, dstSize_tooSmall, "");
if (dst == NULL) {
if (regenSize == 0) return 0;
RETURN_ERROR(dstBuffer_null, "");
}
ZSTD_memset(dst, b, regenSize);
return regenSize;
}
static void ZSTD_DCtx_trace_end(ZSTD_DCtx const* dctx, U64 uncompressedSize, U64 compressedSize, unsigned streaming)
{
#if ZSTD_TRACE
if (dctx->traceCtx && ZSTD_trace_decompress_end != NULL) {
ZSTD_Trace trace;
ZSTD_memset(&trace, 0, sizeof(trace));
trace.version = ZSTD_VERSION_NUMBER;
trace.streaming = streaming;
if (dctx->ddict) {
trace.dictionaryID = ZSTD_getDictID_fromDDict(dctx->ddict);
trace.dictionarySize = ZSTD_DDict_dictSize(dctx->ddict);
trace.dictionaryIsCold = dctx->ddictIsCold;
}
trace.uncompressedSize = (size_t)uncompressedSize;
trace.compressedSize = (size_t)compressedSize;
trace.dctx = dctx;
ZSTD_trace_decompress_end(dctx->traceCtx, &trace);
}
#else
(void)dctx;
(void)uncompressedSize;
(void)compressedSize;
(void)streaming;
#endif
}
/*! ZSTD_decompressFrame() :
* @dctx must be properly initialized
* will update *srcPtr and *srcSizePtr,
* to make *srcPtr progress by one frame. */
static size_t ZSTD_decompressFrame(ZSTD_DCtx* dctx,
void* dst, size_t dstCapacity,
const void** srcPtr, size_t *srcSizePtr)
{
const BYTE* const istart = (const BYTE*)(*srcPtr);
const BYTE* ip = istart;
BYTE* const ostart = (BYTE*)dst;
BYTE* const oend = dstCapacity != 0 ? ostart + dstCapacity : ostart;
BYTE* op = ostart;
size_t remainingSrcSize = *srcSizePtr;
DEBUGLOG(4, "ZSTD_decompressFrame (srcSize:%i)", (int)*srcSizePtr);
/* check */
RETURN_ERROR_IF(
remainingSrcSize < ZSTD_FRAMEHEADERSIZE_MIN(dctx->format)+ZSTD_blockHeaderSize,
srcSize_wrong, "");
/* Frame Header */
{ size_t const frameHeaderSize = ZSTD_frameHeaderSize_internal(
ip, ZSTD_FRAMEHEADERSIZE_PREFIX(dctx->format), dctx->format);
if (ZSTD_isError(frameHeaderSize)) return frameHeaderSize;
RETURN_ERROR_IF(remainingSrcSize < frameHeaderSize+ZSTD_blockHeaderSize,
srcSize_wrong, "");
FORWARD_IF_ERROR( ZSTD_decodeFrameHeader(dctx, ip, frameHeaderSize) , "");
ip += frameHeaderSize; remainingSrcSize -= frameHeaderSize;
}
/* Shrink the blockSizeMax if enabled */
if (dctx->maxBlockSizeParam != 0)
dctx->fParams.blockSizeMax = MIN(dctx->fParams.blockSizeMax, (unsigned)dctx->maxBlockSizeParam);
/* Loop on each block */
while (1) {
BYTE* oBlockEnd = oend;
size_t decodedSize;
blockProperties_t blockProperties;
size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSrcSize, &blockProperties);
if (ZSTD_isError(cBlockSize)) return cBlockSize;
ip += ZSTD_blockHeaderSize;
remainingSrcSize -= ZSTD_blockHeaderSize;
RETURN_ERROR_IF(cBlockSize > remainingSrcSize, srcSize_wrong, "");
if (ip >= op && ip < oBlockEnd) {
/* We are decompressing in-place. Limit the output pointer so that we
* don't overwrite the block that we are currently reading. This will
* fail decompression if the input & output pointers aren't spaced
* far enough apart.
*
* This is important to set, even when the pointers are far enough
* apart, because ZSTD_decompressBlock_internal() can decide to store