/* * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc. * 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. */ /*-************************************* * Dependencies ***************************************/ #include "zstd_compress_superblock.h" #include "../common/zstd_internal.h" /* ZSTD_getSequenceLength */ #include "hist.h" /* HIST_countFast_wksp */ #include "zstd_compress_internal.h" #include "zstd_compress_sequences.h" #include "zstd_compress_literals.h" /*-************************************* * Superblock entropy buffer structs ***************************************/ /** ZSTD_hufCTablesMetadata_t : * Stores Literals Block Type for a super-block in hType, and * huffman tree description in hufDesBuffer. * hufDesSize refers to the size of huffman tree description in bytes. * This metadata is populated in ZSTD_buildSuperBlockEntropy_literal() */ typedef struct { symbolEncodingType_e hType; BYTE hufDesBuffer[500]; /* TODO give name to this value */ size_t hufDesSize; } ZSTD_hufCTablesMetadata_t; /** ZSTD_fseCTablesMetadata_t : * Stores symbol compression modes for a super-block in {ll, ol, ml}Type, and * fse tables in fseTablesBuffer. * fseTablesSize refers to the size of fse tables in bytes. * This metadata is populated in ZSTD_buildSuperBlockEntropy_sequences() */ typedef struct { symbolEncodingType_e llType; symbolEncodingType_e ofType; symbolEncodingType_e mlType; BYTE fseTablesBuffer[500]; /* TODO give name to this value */ size_t fseTablesSize; size_t lastCountSize; /* This is to account for bug in 1.3.4. More detail in ZSTD_compressSubBlock_sequences() */ } ZSTD_fseCTablesMetadata_t; typedef struct { ZSTD_hufCTablesMetadata_t hufMetadata; ZSTD_fseCTablesMetadata_t fseMetadata; } ZSTD_entropyCTablesMetadata_t; /** ZSTD_buildSuperBlockEntropy_literal() : * Builds entropy for the super-block literals. * Stores literals block type (raw, rle, compressed, repeat) and * huffman description table to hufMetadata. * @return : size of huffman description table or error code */ static size_t ZSTD_buildSuperBlockEntropy_literal(void* const src, size_t srcSize, const ZSTD_hufCTables_t* prevHuf, ZSTD_hufCTables_t* nextHuf, ZSTD_hufCTablesMetadata_t* hufMetadata, const int disableLiteralsCompression, void* workspace, size_t wkspSize) { BYTE* const wkspStart = (BYTE*)workspace; BYTE* const wkspEnd = wkspStart + wkspSize; BYTE* const countWkspStart = wkspStart; unsigned* const countWksp = (unsigned*)workspace; const size_t countWkspSize = (HUF_SYMBOLVALUE_MAX + 1) * sizeof(unsigned); BYTE* const nodeWksp = countWkspStart + countWkspSize; const size_t nodeWkspSize = wkspEnd-nodeWksp; unsigned maxSymbolValue = 255; unsigned huffLog = HUF_TABLELOG_DEFAULT; HUF_repeat repeat = prevHuf->repeatMode; DEBUGLOG(5, "ZSTD_buildSuperBlockEntropy_literal (srcSize=%zu)", srcSize); /* Prepare nextEntropy assuming reusing the existing table */ memcpy(nextHuf, prevHuf, sizeof(*prevHuf)); if (disableLiteralsCompression) { DEBUGLOG(5, "set_basic - disabled"); hufMetadata->hType = set_basic; return 0; } /* small ? don't even attempt compression (speed opt) */ # define COMPRESS_LITERALS_SIZE_MIN 63 { size_t const minLitSize = (prevHuf->repeatMode == HUF_repeat_valid) ? 6 : COMPRESS_LITERALS_SIZE_MIN; if (srcSize <= minLitSize) { DEBUGLOG(5, "set_basic - too small"); hufMetadata->hType = set_basic; return 0; } } /* Scan input and build symbol stats */ { size_t const largest = HIST_count_wksp (countWksp, &maxSymbolValue, (const BYTE*)src, srcSize, workspace, wkspSize); FORWARD_IF_ERROR(largest, "HIST_count_wksp failed"); if (largest == srcSize) { DEBUGLOG(5, "set_rle"); hufMetadata->hType = set_rle; return 0; } if (largest <= (srcSize >> 7)+4) { DEBUGLOG(5, "set_basic - no gain"); hufMetadata->hType = set_basic; return 0; } } /* Validate the previous Huffman table */ if (repeat == HUF_repeat_check && !HUF_validateCTable((HUF_CElt const*)prevHuf->CTable, countWksp, maxSymbolValue)) { repeat = HUF_repeat_none; } /* Build Huffman Tree */ memset(nextHuf->CTable, 0, sizeof(nextHuf->CTable)); huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue); { size_t const maxBits = HUF_buildCTable_wksp((HUF_CElt*)nextHuf->CTable, countWksp, maxSymbolValue, huffLog, nodeWksp, nodeWkspSize); FORWARD_IF_ERROR(maxBits, "HUF_buildCTable_wksp"); huffLog = (U32)maxBits; { /* Build and write the CTable */ size_t const newCSize = HUF_estimateCompressedSize( (HUF_CElt*)nextHuf->CTable, countWksp, maxSymbolValue); size_t const hSize = HUF_writeCTable( hufMetadata->hufDesBuffer, sizeof(hufMetadata->hufDesBuffer), (HUF_CElt*)nextHuf->CTable, maxSymbolValue, huffLog); /* Check against repeating the previous CTable */ if (repeat != HUF_repeat_none) { size_t const oldCSize = HUF_estimateCompressedSize( (HUF_CElt const*)prevHuf->CTable, countWksp, maxSymbolValue); if (oldCSize < srcSize && (oldCSize <= hSize + newCSize || hSize + 12 >= srcSize)) { DEBUGLOG(5, "set_repeat - smaller"); memcpy(nextHuf, prevHuf, sizeof(*prevHuf)); hufMetadata->hType = set_repeat; return 0; } } if (newCSize + hSize >= srcSize) { DEBUGLOG(5, "set_basic - no gains"); memcpy(nextHuf, prevHuf, sizeof(*prevHuf)); hufMetadata->hType = set_basic; return 0; } DEBUGLOG(5, "set_compressed (hSize=%u)", (U32)hSize); hufMetadata->hType = set_compressed; nextHuf->repeatMode = HUF_repeat_check; return hSize; } } } /** ZSTD_buildSuperBlockEntropy_sequences() : * Builds entropy for the super-block sequences. * Stores symbol compression modes and fse table to fseMetadata. * @return : size of fse tables or error code */ static size_t ZSTD_buildSuperBlockEntropy_sequences(seqStore_t* seqStorePtr, const ZSTD_fseCTables_t* prevEntropy, ZSTD_fseCTables_t* nextEntropy, const ZSTD_CCtx_params* cctxParams, ZSTD_fseCTablesMetadata_t* fseMetadata, void* workspace, size_t wkspSize) { BYTE* const wkspStart = (BYTE*)workspace; BYTE* const wkspEnd = wkspStart + wkspSize; BYTE* const countWkspStart = wkspStart; unsigned* const countWksp = (unsigned*)workspace; const size_t countWkspSize = (MaxSeq + 1) * sizeof(unsigned); BYTE* const cTableWksp = countWkspStart + countWkspSize; const size_t cTableWkspSize = wkspEnd-cTableWksp; ZSTD_strategy const strategy = cctxParams->cParams.strategy; FSE_CTable* CTable_LitLength = nextEntropy->litlengthCTable; FSE_CTable* CTable_OffsetBits = nextEntropy->offcodeCTable; FSE_CTable* CTable_MatchLength = nextEntropy->matchlengthCTable; const BYTE* const ofCodeTable = seqStorePtr->ofCode; const BYTE* const llCodeTable = seqStorePtr->llCode; const BYTE* const mlCodeTable = seqStorePtr->mlCode; size_t const nbSeq = seqStorePtr->sequences - seqStorePtr->sequencesStart; BYTE* const ostart = fseMetadata->fseTablesBuffer; BYTE* const oend = ostart + sizeof(fseMetadata->fseTablesBuffer); BYTE* op = ostart; assert(cTableWkspSize >= (1 << MaxFSELog) * sizeof(FSE_FUNCTION_TYPE)); DEBUGLOG(5, "ZSTD_buildSuperBlockEntropy_sequences (nbSeq=%zu)", nbSeq); memset(workspace, 0, wkspSize); fseMetadata->lastCountSize = 0; /* convert length/distances into codes */ ZSTD_seqToCodes(seqStorePtr); /* build CTable for Literal Lengths */ { U32 LLtype; unsigned max = MaxLL; size_t const mostFrequent = HIST_countFast_wksp(countWksp, &max, llCodeTable, nbSeq, workspace, wkspSize); /* can't fail */ DEBUGLOG(5, "Building LL table"); nextEntropy->litlength_repeatMode = prevEntropy->litlength_repeatMode; LLtype = ZSTD_selectEncodingType(&nextEntropy->litlength_repeatMode, countWksp, max, mostFrequent, nbSeq, LLFSELog, prevEntropy->litlengthCTable, LL_defaultNorm, LL_defaultNormLog, ZSTD_defaultAllowed, strategy); assert(set_basic < set_compressed && set_rle < set_compressed); assert(!(LLtype < set_compressed && nextEntropy->litlength_repeatMode != FSE_repeat_none)); /* We don't copy tables */ { size_t const countSize = ZSTD_buildCTable(op, oend - op, CTable_LitLength, LLFSELog, (symbolEncodingType_e)LLtype, countWksp, max, llCodeTable, nbSeq, LL_defaultNorm, LL_defaultNormLog, MaxLL, prevEntropy->litlengthCTable, sizeof(prevEntropy->litlengthCTable), cTableWksp, cTableWkspSize); FORWARD_IF_ERROR(countSize, "ZSTD_buildCTable for LitLens failed"); if (LLtype == set_compressed) fseMetadata->lastCountSize = countSize; op += countSize; fseMetadata->llType = (symbolEncodingType_e) LLtype; } } /* build CTable for Offsets */ { U32 Offtype; unsigned max = MaxOff; size_t const mostFrequent = HIST_countFast_wksp(countWksp, &max, ofCodeTable, nbSeq, workspace, wkspSize); /* can't fail */ /* We can only use the basic table if max <= DefaultMaxOff, otherwise the offsets are too large */ ZSTD_defaultPolicy_e const defaultPolicy = (max <= DefaultMaxOff) ? ZSTD_defaultAllowed : ZSTD_defaultDisallowed; DEBUGLOG(5, "Building OF table"); nextEntropy->offcode_repeatMode = prevEntropy->offcode_repeatMode; Offtype = ZSTD_selectEncodingType(&nextEntropy->offcode_repeatMode, countWksp, max, mostFrequent, nbSeq, OffFSELog, prevEntropy->offcodeCTable, OF_defaultNorm, OF_defaultNormLog, defaultPolicy, strategy); assert(!(Offtype < set_compressed && nextEntropy->offcode_repeatMode != FSE_repeat_none)); /* We don't copy tables */ { size_t const countSize = ZSTD_buildCTable(op, oend - op, CTable_OffsetBits, OffFSELog, (symbolEncodingType_e)Offtype, countWksp, max, ofCodeTable, nbSeq, OF_defaultNorm, OF_defaultNormLog, DefaultMaxOff, prevEntropy->offcodeCTable, sizeof(prevEntropy->offcodeCTable), cTableWksp, cTableWkspSize); FORWARD_IF_ERROR(countSize, "ZSTD_buildCTable for Offsets failed"); if (Offtype == set_compressed) fseMetadata->lastCountSize = countSize; op += countSize; fseMetadata->ofType = (symbolEncodingType_e) Offtype; } } /* build CTable for MatchLengths */ { U32 MLtype; unsigned max = MaxML; size_t const mostFrequent = HIST_countFast_wksp(countWksp, &max, mlCodeTable, nbSeq, workspace, wkspSize); /* can't fail */ DEBUGLOG(5, "Building ML table (remaining space : %i)", (int)(oend-op)); nextEntropy->matchlength_repeatMode = prevEntropy->matchlength_repeatMode; MLtype = ZSTD_selectEncodingType(&nextEntropy->matchlength_repeatMode, countWksp, max, mostFrequent, nbSeq, MLFSELog, prevEntropy->matchlengthCTable, ML_defaultNorm, ML_defaultNormLog, ZSTD_defaultAllowed, strategy); assert(!(MLtype < set_compressed && nextEntropy->matchlength_repeatMode != FSE_repeat_none)); /* We don't copy tables */ { size_t const countSize = ZSTD_buildCTable(op, oend - op, CTable_MatchLength, MLFSELog, (symbolEncodingType_e)MLtype, countWksp, max, mlCodeTable, nbSeq, ML_defaultNorm, ML_defaultNormLog, MaxML, prevEntropy->matchlengthCTable, sizeof(prevEntropy->matchlengthCTable), cTableWksp, cTableWkspSize); FORWARD_IF_ERROR(countSize, "ZSTD_buildCTable for MatchLengths failed"); if (MLtype == set_compressed) fseMetadata->lastCountSize = countSize; op += countSize; fseMetadata->mlType = (symbolEncodingType_e) MLtype; } } assert((size_t) (op-ostart) <= sizeof(fseMetadata->fseTablesBuffer)); return op-ostart; } /** ZSTD_buildSuperBlockEntropy() : * Builds entropy for the super-block. * @return : 0 on success or error code */ static size_t ZSTD_buildSuperBlockEntropy(seqStore_t* seqStorePtr, const ZSTD_entropyCTables_t* prevEntropy, ZSTD_entropyCTables_t* nextEntropy, const ZSTD_CCtx_params* cctxParams, ZSTD_entropyCTablesMetadata_t* entropyMetadata, void* workspace, size_t wkspSize) { size_t const litSize = seqStorePtr->lit - seqStorePtr->litStart; DEBUGLOG(5, "ZSTD_buildSuperBlockEntropy"); entropyMetadata->hufMetadata.hufDesSize = ZSTD_buildSuperBlockEntropy_literal(seqStorePtr->litStart, litSize, &prevEntropy->huf, &nextEntropy->huf, &entropyMetadata->hufMetadata, ZSTD_disableLiteralsCompression(cctxParams), workspace, wkspSize); FORWARD_IF_ERROR(entropyMetadata->hufMetadata.hufDesSize, "ZSTD_buildSuperBlockEntropy_literal failed"); entropyMetadata->fseMetadata.fseTablesSize = ZSTD_buildSuperBlockEntropy_sequences(seqStorePtr, &prevEntropy->fse, &nextEntropy->fse, cctxParams, &entropyMetadata->fseMetadata, workspace, wkspSize); FORWARD_IF_ERROR(entropyMetadata->fseMetadata.fseTablesSize, "ZSTD_buildSuperBlockEntropy_sequences failed"); return 0; } /** ZSTD_compressSubBlock_literal() : * Compresses literals section for a sub-block. * When we have to write the Huffman table we will sometimes choose a header * size larger than necessary. This is because we have to pick the header size * before we know the table size + compressed size, so we have a bound on the * table size. If we guessed incorrectly, we fall back to uncompressed literals. * * We write the header when writeEntropy=1 and set entropyWrriten=1 when we succeeded * in writing the header, otherwise it is set to 0. * * hufMetadata->hType has literals block type info. * If it is set_basic, all sub-blocks literals section will be Raw_Literals_Block. * If it is set_rle, all sub-blocks literals section will be RLE_Literals_Block. * If it is set_compressed, first sub-block's literals section will be Compressed_Literals_Block * If it is set_compressed, first sub-block's literals section will be Treeless_Literals_Block * and the following sub-blocks' literals sections will be Treeless_Literals_Block. * @return : compressed size of literals section of a sub-block * Or 0 if it unable to compress. * Or error code */ static size_t ZSTD_compressSubBlock_literal(const HUF_CElt* hufTable, const ZSTD_hufCTablesMetadata_t* hufMetadata, const BYTE* literals, size_t litSize, void* dst, size_t dstSize, const int bmi2, int writeEntropy, int* entropyWritten) { size_t const header = writeEntropy ? 200 : 0; size_t const lhSize = 3 + (litSize >= (1 KB - header)) + (litSize >= (16 KB - header)); BYTE* const ostart = (BYTE*)dst; BYTE* const oend = ostart + dstSize; BYTE* op = ostart + lhSize; U32 const singleStream = lhSize == 3; symbolEncodingType_e hType = writeEntropy ? hufMetadata->hType : set_repeat; size_t cLitSize = 0; (void)bmi2; /* TODO bmi2... */ DEBUGLOG(5, "ZSTD_compressSubBlock_literal (litSize=%zu, lhSize=%zu, writeEntropy=%d)", litSize, lhSize, writeEntropy); *entropyWritten = 0; if (litSize == 0 || hufMetadata->hType == set_basic) { DEBUGLOG(5, "ZSTD_compressSubBlock_literal using raw literal"); return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize); } else if (hufMetadata->hType == set_rle) { DEBUGLOG(5, "ZSTD_compressSubBlock_literal using rle literal"); return ZSTD_compressRleLiteralsBlock(dst, dstSize, literals, litSize); } assert(litSize > 0); assert(hufMetadata->hType == set_compressed || hufMetadata->hType == set_repeat); if (writeEntropy && hufMetadata->hType == set_compressed) { memcpy(op, hufMetadata->hufDesBuffer, hufMetadata->hufDesSize); op += hufMetadata->hufDesSize; cLitSize += hufMetadata->hufDesSize; DEBUGLOG(5, "ZSTD_compressSubBlock_literal (hSize=%zu)", hufMetadata->hufDesSize); } /* TODO bmi2 */ { const size_t cSize = singleStream ? HUF_compress1X_usingCTable(op, oend-op, literals, litSize, hufTable) : HUF_compress4X_usingCTable(op, oend-op, literals, litSize, hufTable); op += cSize; cLitSize += cSize; if (cSize == 0 || ERR_isError(cSize)) { DEBUGLOG(5, "Failed to write entropy tables %s", ZSTD_getErrorName(cSize)); return 0; } /* If we expand and we aren't writing a header then emit uncompressed */ if (!writeEntropy && cLitSize >= litSize) { DEBUGLOG(5, "ZSTD_compressSubBlock_literal using raw literal because uncompressible"); return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize); } /* If we are writing headers then allow expansion that doesn't change our header size. */ if (lhSize < (size_t)(3 + (cLitSize >= 1 KB) + (cLitSize >= 16 KB))) { assert(cLitSize > litSize); DEBUGLOG(5, "Literals expanded beyond allowed header size"); return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize); } DEBUGLOG(5, "ZSTD_compressSubBlock_literal (cSize=%zu)", cSize); } /* Build header */ switch(lhSize) { case 3: /* 2 - 2 - 10 - 10 */ { U32 const lhc = hType + ((!singleStream) << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<14); MEM_writeLE24(ostart, lhc); break; } case 4: /* 2 - 2 - 14 - 14 */ { U32 const lhc = hType + (2 << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<18); MEM_writeLE32(ostart, lhc); break; } case 5: /* 2 - 2 - 18 - 18 */ { U32 const lhc = hType + (3 << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<22); MEM_writeLE32(ostart, lhc); ostart[4] = (BYTE)(cLitSize >> 10); break; } default: /* not possible : lhSize is {3,4,5} */ assert(0); } *entropyWritten = 1; DEBUGLOG(5, "Compressed literals: %u -> %u", (U32)litSize, (U32)(op-ostart)); return op-ostart; } static size_t ZSTD_seqDecompressedSize(seqStore_t const* seqStore, const seqDef* sequences, size_t nbSeq, size_t litSize, int lastSequence) { const seqDef* const sstart = sequences; const seqDef* const send = sequences + nbSeq; const seqDef* sp = sstart; size_t matchLengthSum = 0; size_t litLengthSum = 0; while (send-sp > 0) { ZSTD_sequenceLength const seqLen = ZSTD_getSequenceLength(seqStore, sp); litLengthSum += seqLen.litLength; matchLengthSum += seqLen.matchLength; sp++; } assert(litLengthSum <= litSize); if (!lastSequence) { assert(litLengthSum == litSize); } return matchLengthSum + litSize; } /** ZSTD_compressSubBlock_sequences() : * Compresses sequences section for a sub-block. * fseMetadata->llType, fseMetadata->ofType, and fseMetadata->mlType have * symbol compression modes for the super-block. * The first successfully compressed block will have these in its header. * We set entropyWritten=1 when we succeed in compressing the sequences. * The following sub-blocks will always have repeat mode. * @return : compressed size of sequences section of a sub-block * Or 0 if it is unable to compress * Or error code. */ static size_t ZSTD_compressSubBlock_sequences(const ZSTD_fseCTables_t* fseTables, const ZSTD_fseCTablesMetadata_t* fseMetadata, const seqDef* sequences, size_t nbSeq, const BYTE* llCode, const BYTE* mlCode, const BYTE* ofCode, const ZSTD_CCtx_params* cctxParams, void* dst, size_t dstCapacity, const int bmi2, int writeEntropy, int* entropyWritten) { const int longOffsets = cctxParams->cParams.windowLog > STREAM_ACCUMULATOR_MIN; BYTE* const ostart = (BYTE*)dst; BYTE* const oend = ostart + dstCapacity; BYTE* op = ostart; BYTE* seqHead; DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (nbSeq=%zu, writeEntropy=%d, longOffsets=%d)", nbSeq, writeEntropy, longOffsets); *entropyWritten = 0; /* Sequences Header */ RETURN_ERROR_IF((oend-op) < 3 /*max nbSeq Size*/ + 1 /*seqHead*/, dstSize_tooSmall, ""); if (nbSeq < 0x7F) *op++ = (BYTE)nbSeq; else if (nbSeq < LONGNBSEQ) op[0] = (BYTE)((nbSeq>>8) + 0x80), op[1] = (BYTE)nbSeq, op+=2; else op[0]=0xFF, MEM_writeLE16(op+1, (U16)(nbSeq - LONGNBSEQ)), op+=3; if (nbSeq==0) { return op - ostart; } /* seqHead : flags for FSE encoding type */ seqHead = op++; DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (seqHeadSize=%u)", (unsigned)(op-ostart)); if (writeEntropy) { const U32 LLtype = fseMetadata->llType; const U32 Offtype = fseMetadata->ofType; const U32 MLtype = fseMetadata->mlType; DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (fseTablesSize=%zu)", fseMetadata->fseTablesSize); *seqHead = (BYTE)((LLtype<<6) + (Offtype<<4) + (MLtype<<2)); memcpy(op, fseMetadata->fseTablesBuffer, fseMetadata->fseTablesSize); op += fseMetadata->fseTablesSize; } else { const U32 repeat = set_repeat; *seqHead = (BYTE)((repeat<<6) + (repeat<<4) + (repeat<<2)); } { size_t const bitstreamSize = ZSTD_encodeSequences( op, oend - op, fseTables->matchlengthCTable, mlCode, fseTables->offcodeCTable, ofCode, fseTables->litlengthCTable, llCode, sequences, nbSeq, longOffsets, bmi2); FORWARD_IF_ERROR(bitstreamSize, "ZSTD_encodeSequences failed"); op += bitstreamSize; /* zstd versions <= 1.3.4 mistakenly report corruption when * FSE_readNCount() receives a buffer < 4 bytes. * Fixed by https://github.com/facebook/zstd/pull/1146. * This can happen when the last set_compressed table present is 2 * bytes and the bitstream is only one byte. * In this exceedingly rare case, we will simply emit an uncompressed * block, since it isn't worth optimizing. */ #ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION if (writeEntropy && fseMetadata->lastCountSize && fseMetadata->lastCountSize + bitstreamSize < 4) { /* NCountSize >= 2 && bitstreamSize > 0 ==> lastCountSize == 3 */ assert(fseMetadata->lastCountSize + bitstreamSize == 3); DEBUGLOG(5, "Avoiding bug in zstd decoder in versions <= 1.3.4 by " "emitting an uncompressed block."); return 0; } #endif DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (bitstreamSize=%zu)", bitstreamSize); } /* zstd versions <= 1.4.0 mistakenly report error when * sequences section body size is less than 3 bytes. * Fixed by https://github.com/facebook/zstd/pull/1664. * This can happen when the previous sequences section block is compressed * with rle mode and the current block's sequences section is compressed * with repeat mode where sequences section body size can be 1 byte. */ #ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION if (op-seqHead < 4) { DEBUGLOG(5, "Avoiding bug in zstd decoder in versions <= 1.4.0 by emitting " "an uncompressed block when sequences are < 4 bytes"); return 0; } #endif *entropyWritten = 1; return op - ostart; } /** ZSTD_compressSubBlock() : * Compresses a single sub-block. * @return : compressed size of the sub-block * Or 0 if it failed to compress. */ static size_t ZSTD_compressSubBlock(const ZSTD_entropyCTables_t* entropy, const ZSTD_entropyCTablesMetadata_t* entropyMetadata, const seqDef* sequences, size_t nbSeq, const BYTE* literals, size_t litSize, const BYTE* llCode, const BYTE* mlCode, const BYTE* ofCode, const ZSTD_CCtx_params* cctxParams, void* dst, size_t dstCapacity, const int bmi2, int writeLitEntropy, int writeSeqEntropy, int* litEntropyWritten, int* seqEntropyWritten, U32 lastBlock) { BYTE* const ostart = (BYTE*)dst; BYTE* const oend = ostart + dstCapacity; BYTE* op = ostart + ZSTD_blockHeaderSize; DEBUGLOG(5, "ZSTD_compressSubBlock (litSize=%zu, nbSeq=%zu, writeLitEntropy=%d, writeSeqEntropy=%d, lastBlock=%d)", litSize, nbSeq, writeLitEntropy, writeSeqEntropy, lastBlock); { size_t cLitSize = ZSTD_compressSubBlock_literal((const HUF_CElt*)entropy->huf.CTable, &entropyMetadata->hufMetadata, literals, litSize, op, oend-op, bmi2, writeLitEntropy, litEntropyWritten); FORWARD_IF_ERROR(cLitSize, "ZSTD_compressSubBlock_literal failed"); if (cLitSize == 0) return 0; op += cLitSize; } { size_t cSeqSize = ZSTD_compressSubBlock_sequences(&entropy->fse, &entropyMetadata->fseMetadata, sequences, nbSeq, llCode, mlCode, ofCode, cctxParams, op, oend-op, bmi2, writeSeqEntropy, seqEntropyWritten); FORWARD_IF_ERROR(cSeqSize, "ZSTD_compressSubBlock_sequences failed"); if (cSeqSize == 0) return 0; op += cSeqSize; } /* Write block header */ { size_t cSize = (op-ostart)-ZSTD_blockHeaderSize; U32 const cBlockHeader24 = lastBlock + (((U32)bt_compressed)<<1) + (U32)(cSize << 3); MEM_writeLE24(ostart, cBlockHeader24); } return op-ostart; } static size_t ZSTD_estimateSubBlockSize_literal(const BYTE* literals, size_t litSize, const ZSTD_hufCTables_t* huf, const ZSTD_hufCTablesMetadata_t* hufMetadata, void* workspace, size_t wkspSize, int writeEntropy) { unsigned* const countWksp = (unsigned*)workspace; unsigned maxSymbolValue = 255; size_t literalSectionHeaderSize = 3; /* Use hard coded size of 3 bytes */ if (hufMetadata->hType == set_basic) return litSize; else if (hufMetadata->hType == set_rle) return 1; else if (hufMetadata->hType == set_compressed || hufMetadata->hType == set_repeat) { size_t const largest = HIST_count_wksp (countWksp, &maxSymbolValue, (const BYTE*)literals, litSize, workspace, wkspSize); if (ZSTD_isError(largest)) return litSize; { size_t cLitSizeEstimate = HUF_estimateCompressedSize((const HUF_CElt*)huf->CTable, countWksp, maxSymbolValue); if (writeEntropy) cLitSizeEstimate += hufMetadata->hufDesSize; return cLitSizeEstimate + literalSectionHeaderSize; } } assert(0); /* impossible */ return 0; } static size_t ZSTD_estimateSubBlockSize_symbolType(symbolEncodingType_e type, const BYTE* codeTable, unsigned maxCode, size_t nbSeq, const FSE_CTable* fseCTable, const U32* additionalBits, short const* defaultNorm, U32 defaultNormLog, void* workspace, size_t wkspSize) { unsigned* const countWksp = (unsigned*)workspace; const BYTE* ctp = codeTable; const BYTE* const ctStart = ctp; const BYTE* const ctEnd = ctStart + nbSeq; size_t cSymbolTypeSizeEstimateInBits = 0; unsigned max = maxCode; HIST_countFast_wksp(countWksp, &max, codeTable, nbSeq, workspace, wkspSize); /* can't fail */ if (type == set_basic) { cSymbolTypeSizeEstimateInBits = ZSTD_crossEntropyCost(defaultNorm, defaultNormLog, countWksp, max); } else if (type == set_rle) { cSymbolTypeSizeEstimateInBits = 0; } else if (type == set_compressed || type == set_repeat) { cSymbolTypeSizeEstimateInBits = ZSTD_fseBitCost(fseCTable, countWksp, max); } if (ZSTD_isError(cSymbolTypeSizeEstimateInBits)) return nbSeq * 10; while (ctp < ctEnd) { if (additionalBits) cSymbolTypeSizeEstimateInBits += additionalBits[*ctp]; else cSymbolTypeSizeEstimateInBits += *ctp; /* for offset, offset code is also the number of additional bits */ ctp++; } return cSymbolTypeSizeEstimateInBits / 8; } static size_t ZSTD_estimateSubBlockSize_sequences(const BYTE* ofCodeTable, const BYTE* llCodeTable, const BYTE* mlCodeTable, size_t nbSeq, const ZSTD_fseCTables_t* fseTables, const ZSTD_fseCTablesMetadata_t* fseMetadata, void* workspace, size_t wkspSize, int writeEntropy) { size_t sequencesSectionHeaderSize = 3; /* Use hard coded size of 3 bytes */ size_t cSeqSizeEstimate = 0; cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->ofType, ofCodeTable, MaxOff, nbSeq, fseTables->offcodeCTable, NULL, OF_defaultNorm, OF_defaultNormLog, workspace, wkspSize); cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->llType, llCodeTable, MaxLL, nbSeq, fseTables->litlengthCTable, LL_bits, LL_defaultNorm, LL_defaultNormLog, workspace, wkspSize); cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->mlType, mlCodeTable, MaxML, nbSeq, fseTables->matchlengthCTable, ML_bits, ML_defaultNorm, ML_defaultNormLog, workspace, wkspSize); if (writeEntropy) cSeqSizeEstimate += fseMetadata->fseTablesSize; return cSeqSizeEstimate + sequencesSectionHeaderSize; } static size_t ZSTD_estimateSubBlockSize(const BYTE* literals, size_t litSize, const BYTE* ofCodeTable, const BYTE* llCodeTable, const BYTE* mlCodeTable, size_t nbSeq, const ZSTD_entropyCTables_t* entropy, const ZSTD_entropyCTablesMetadata_t* entropyMetadata, void* workspace, size_t wkspSize, int writeLitEntropy, int writeSeqEntropy) { size_t cSizeEstimate = 0; cSizeEstimate += ZSTD_estimateSubBlockSize_literal(literals, litSize, &entropy->huf, &entropyMetadata->hufMetadata, workspace, wkspSize, writeLitEntropy); cSizeEstimate += ZSTD_estimateSubBlockSize_sequences(ofCodeTable, llCodeTable, mlCodeTable, nbSeq, &entropy->fse, &entropyMetadata->fseMetadata, workspace, wkspSize, writeSeqEntropy); return cSizeEstimate + ZSTD_blockHeaderSize; } static int ZSTD_needSequenceEntropyTables(ZSTD_fseCTablesMetadata_t const* fseMetadata) { if (fseMetadata->llType == set_compressed || fseMetadata->llType == set_rle) return 1; if (fseMetadata->mlType == set_compressed || fseMetadata->mlType == set_rle) return 1; if (fseMetadata->ofType == set_compressed || fseMetadata->ofType == set_rle) return 1; return 0; } /** ZSTD_compressSubBlock_multi() : * Breaks super-block into multiple sub-blocks and compresses them. * Entropy will be written to the first block. * The following blocks will use repeat mode to compress. * All sub-blocks are compressed blocks (no raw or rle blocks). * @return : compressed size of the super block (which is multiple ZSTD blocks) * Or 0 if it failed to compress. */ static size_t ZSTD_compressSubBlock_multi(const seqStore_t* seqStorePtr, const ZSTD_compressedBlockState_t* prevCBlock, ZSTD_compressedBlockState_t* nextCBlock, const ZSTD_entropyCTablesMetadata_t* entropyMetadata, const ZSTD_CCtx_params* cctxParams, void* dst, size_t dstCapacity, const void* src, size_t srcSize, const int bmi2, U32 lastBlock, void* workspace, size_t wkspSize) { const seqDef* const sstart = seqStorePtr->sequencesStart; const seqDef* const send = seqStorePtr->sequences; const seqDef* sp = sstart; const BYTE* const lstart = seqStorePtr->litStart; const BYTE* const lend = seqStorePtr->lit; const BYTE* lp = lstart; BYTE const* ip = (BYTE const*)src; BYTE const* const iend = ip + srcSize; BYTE* const ostart = (BYTE*)dst; BYTE* const oend = ostart + dstCapacity; BYTE* op = ostart; const BYTE* llCodePtr = seqStorePtr->llCode; const BYTE* mlCodePtr = seqStorePtr->mlCode; const BYTE* ofCodePtr = seqStorePtr->ofCode; size_t targetCBlockSize = cctxParams->targetCBlockSize; size_t litSize, seqCount; int writeLitEntropy = entropyMetadata->hufMetadata.hType == set_compressed; int writeSeqEntropy = 1; int lastSequence = 0; DEBUGLOG(5, "ZSTD_compressSubBlock_multi (litSize=%u, nbSeq=%u)", (unsigned)(lend-lp), (unsigned)(send-sstart)); litSize = 0; seqCount = 0; do { size_t cBlockSizeEstimate = 0; if (sstart == send) { lastSequence = 1; } else { const seqDef* const sequence = sp + seqCount; lastSequence = sequence == send - 1; litSize += ZSTD_getSequenceLength(seqStorePtr, sequence).litLength; seqCount++; } if (lastSequence) { assert(lp <= lend); assert(litSize <= (size_t)(lend - lp)); litSize = (size_t)(lend - lp); } /* I think there is an optimization opportunity here. * Calling ZSTD_estimateSubBlockSize for every sequence can be wasteful * since it recalculates estimate from scratch. * For example, it would recount literal distribution and symbol codes everytime. */ cBlockSizeEstimate = ZSTD_estimateSubBlockSize(lp, litSize, ofCodePtr, llCodePtr, mlCodePtr, seqCount, &nextCBlock->entropy, entropyMetadata, workspace, wkspSize, writeLitEntropy, writeSeqEntropy); if (cBlockSizeEstimate > targetCBlockSize || lastSequence) { int litEntropyWritten = 0; int seqEntropyWritten = 0; const size_t decompressedSize = ZSTD_seqDecompressedSize(seqStorePtr, sp, seqCount, litSize, lastSequence); const size_t cSize = ZSTD_compressSubBlock(&nextCBlock->entropy, entropyMetadata, sp, seqCount, lp, litSize, llCodePtr, mlCodePtr, ofCodePtr, cctxParams, op, oend-op, bmi2, writeLitEntropy, writeSeqEntropy, &litEntropyWritten, &seqEntropyWritten, lastBlock && lastSequence); FORWARD_IF_ERROR(cSize, "ZSTD_compressSubBlock failed"); if (cSize > 0 && cSize < decompressedSize) { DEBUGLOG(5, "Committed the sub-block"); assert(ip + decompressedSize <= iend); ip += decompressedSize; sp += seqCount; lp += litSize; op += cSize; llCodePtr += seqCount; mlCodePtr += seqCount; ofCodePtr += seqCount; litSize = 0; seqCount = 0; /* Entropy only needs to be written once */ if (litEntropyWritten) { writeLitEntropy = 0; } if (seqEntropyWritten) { writeSeqEntropy = 0; } } } } while (!lastSequence); if (writeLitEntropy) { DEBUGLOG(5, "ZSTD_compressSubBlock_multi has literal entropy tables unwritten"); memcpy(&nextCBlock->entropy.huf, &prevCBlock->entropy.huf, sizeof(prevCBlock->entropy.huf)); } if (writeSeqEntropy && ZSTD_needSequenceEntropyTables(&entropyMetadata->fseMetadata)) { /* If we haven't written our entropy tables, then we've violated our contract and * must emit an uncompressed block. */ DEBUGLOG(5, "ZSTD_compressSubBlock_multi has sequence entropy tables unwritten"); return 0; } if (ip < iend) { size_t const cSize = ZSTD_noCompressBlock(op, oend - op, ip, iend - ip, lastBlock); DEBUGLOG(5, "ZSTD_compressSubBlock_multi last sub-block uncompressed, %zu bytes", (size_t)(iend - ip)); FORWARD_IF_ERROR(cSize, "ZSTD_noCompressBlock failed"); assert(cSize != 0); op += cSize; /* We have to regenerate the repcodes because we've skipped some sequences */ if (sp < send) { seqDef const* seq; repcodes_t rep; memcpy(&rep, prevCBlock->rep, sizeof(rep)); for (seq = sstart; seq < sp; ++seq) { rep = ZSTD_updateRep(rep.rep, seq->offset - 1, ZSTD_getSequenceLength(seqStorePtr, seq).litLength == 0); } memcpy(nextCBlock->rep, &rep, sizeof(rep)); } } DEBUGLOG(5, "ZSTD_compressSubBlock_multi compressed"); return op-ostart; } size_t ZSTD_compressSuperBlock(ZSTD_CCtx* zc, void* dst, size_t dstCapacity, void const* src, size_t srcSize, unsigned lastBlock) { ZSTD_entropyCTablesMetadata_t entropyMetadata; FORWARD_IF_ERROR(ZSTD_buildSuperBlockEntropy(&zc->seqStore, &zc->blockState.prevCBlock->entropy, &zc->blockState.nextCBlock->entropy, &zc->appliedParams, &entropyMetadata, zc->entropyWorkspace, HUF_WORKSPACE_SIZE /* statically allocated in resetCCtx */), ""); return ZSTD_compressSubBlock_multi(&zc->seqStore, zc->blockState.prevCBlock, zc->blockState.nextCBlock, &entropyMetadata, &zc->appliedParams, dst, dstCapacity, src, srcSize, zc->bmi2, lastBlock, zc->entropyWorkspace, HUF_WORKSPACE_SIZE /* statically allocated in resetCCtx */); }