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view contrib/python-zstandard/zstd/decompress/zstd_decompress.c @ 30491:13251523b20c
commands: refer to dirstateguard by its new name
| author | Augie Fackler <augie@google.com> |
|---|---|
| date | Mon, 21 Nov 2016 21:06:22 -0500 |
| parents | 2e484bdea8c4 |
| children | b54a2984cdd4 |
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/** * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. * All rights reserved. * * This source code is licensed under the BSD-style license found in the * LICENSE file in the root directory of this source tree. An additional grant * of patent rights can be found in the PATENTS file in the same directory. */ /* *************************************************************** * Tuning parameters *****************************************************************/ /*! * HEAPMODE : * Select how default decompression function ZSTD_decompress() will allocate memory, * in memory stack (0), or in memory heap (1, requires malloc()) */ #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. */ #ifndef ZSTD_MAXWINDOWSIZE_DEFAULT # define ZSTD_MAXWINDOWSIZE_DEFAULT ((1 << ZSTD_WINDOWLOG_MAX) + 1) /* defined within zstd.h */ #endif /*-******************************************************* * Dependencies *********************************************************/ #include <string.h> /* memcpy, memmove, memset */ #include "mem.h" /* low level memory routines */ #define XXH_STATIC_LINKING_ONLY /* XXH64_state_t */ #include "xxhash.h" /* XXH64_* */ #define FSE_STATIC_LINKING_ONLY #include "fse.h" #define HUF_STATIC_LINKING_ONLY #include "huf.h" #include "zstd_internal.h" #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1) # include "zstd_legacy.h" #endif /*-************************************* * Macros ***************************************/ #define ZSTD_isError ERR_isError /* for inlining */ #define FSE_isError ERR_isError #define HUF_isError ERR_isError /*_******************************************************* * Memory operations **********************************************************/ static void ZSTD_copy4(void* dst, const void* src) { memcpy(dst, src, 4); } /*-************************************************************* * Context management ***************************************************************/ typedef enum { ZSTDds_getFrameHeaderSize, ZSTDds_decodeFrameHeader, ZSTDds_decodeBlockHeader, ZSTDds_decompressBlock, ZSTDds_decompressLastBlock, ZSTDds_checkChecksum, ZSTDds_decodeSkippableHeader, ZSTDds_skipFrame } ZSTD_dStage; struct ZSTD_DCtx_s { const FSE_DTable* LLTptr; const FSE_DTable* MLTptr; const FSE_DTable* OFTptr; const HUF_DTable* HUFptr; FSE_DTable LLTable[FSE_DTABLE_SIZE_U32(LLFSELog)]; FSE_DTable OFTable[FSE_DTABLE_SIZE_U32(OffFSELog)]; FSE_DTable MLTable[FSE_DTABLE_SIZE_U32(MLFSELog)]; HUF_DTable hufTable[HUF_DTABLE_SIZE(HufLog)]; /* can accommodate HUF_decompress4X */ const void* previousDstEnd; const void* base; const void* vBase; const void* dictEnd; size_t expected; U32 rep[ZSTD_REP_NUM]; ZSTD_frameParams fParams; blockType_e bType; /* used in ZSTD_decompressContinue(), to transfer blockType between header decoding and block decoding stages */ ZSTD_dStage stage; U32 litEntropy; U32 fseEntropy; XXH64_state_t xxhState; size_t headerSize; U32 dictID; const BYTE* litPtr; ZSTD_customMem customMem; size_t litBufSize; size_t litSize; size_t rleSize; BYTE litBuffer[ZSTD_BLOCKSIZE_ABSOLUTEMAX + WILDCOPY_OVERLENGTH]; BYTE headerBuffer[ZSTD_FRAMEHEADERSIZE_MAX]; }; /* typedef'd to ZSTD_DCtx within "zstd.h" */ size_t ZSTD_sizeof_DCtx (const ZSTD_DCtx* dctx) { return (dctx==NULL) ? 0 : sizeof(ZSTD_DCtx); } size_t ZSTD_estimateDCtxSize(void) { return sizeof(ZSTD_DCtx); } size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx) { dctx->expected = ZSTD_frameHeaderSize_prefix; dctx->stage = ZSTDds_getFrameHeaderSize; dctx->previousDstEnd = NULL; dctx->base = NULL; dctx->vBase = NULL; dctx->dictEnd = NULL; dctx->hufTable[0] = (HUF_DTable)((HufLog)*0x1000001); /* cover both little and big endian */ dctx->litEntropy = dctx->fseEntropy = 0; dctx->dictID = 0; MEM_STATIC_ASSERT(sizeof(dctx->rep) == sizeof(repStartValue)); memcpy(dctx->rep, repStartValue, sizeof(repStartValue)); /* initial repcodes */ dctx->LLTptr = dctx->LLTable; dctx->MLTptr = dctx->MLTable; dctx->OFTptr = dctx->OFTable; dctx->HUFptr = dctx->hufTable; return 0; } ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem) { ZSTD_DCtx* dctx; if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem; if (!customMem.customAlloc || !customMem.customFree) return NULL; dctx = (ZSTD_DCtx*)ZSTD_malloc(sizeof(ZSTD_DCtx), customMem); if (!dctx) return NULL; memcpy(&dctx->customMem, &customMem, sizeof(customMem)); ZSTD_decompressBegin(dctx); return dctx; } ZSTD_DCtx* ZSTD_createDCtx(void) { return ZSTD_createDCtx_advanced(defaultCustomMem); } size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx) { if (dctx==NULL) return 0; /* support free on NULL */ ZSTD_free(dctx, dctx->customMem); return 0; /* reserved as a potential error code in the future */ } void ZSTD_copyDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx) { size_t const workSpaceSize = (ZSTD_BLOCKSIZE_ABSOLUTEMAX+WILDCOPY_OVERLENGTH) + ZSTD_frameHeaderSize_max; memcpy(dstDCtx, srcDCtx, sizeof(ZSTD_DCtx) - workSpaceSize); /* no need to copy workspace */ } static void ZSTD_refDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx) { ZSTD_decompressBegin(dstDCtx); /* init */ if (srcDCtx) { /* support refDCtx on NULL */ dstDCtx->dictEnd = srcDCtx->dictEnd; dstDCtx->vBase = srcDCtx->vBase; dstDCtx->base = srcDCtx->base; dstDCtx->previousDstEnd = srcDCtx->previousDstEnd; dstDCtx->dictID = srcDCtx->dictID; dstDCtx->litEntropy = srcDCtx->litEntropy; dstDCtx->fseEntropy = srcDCtx->fseEntropy; dstDCtx->LLTptr = srcDCtx->LLTable; dstDCtx->MLTptr = srcDCtx->MLTable; dstDCtx->OFTptr = srcDCtx->OFTable; dstDCtx->HUFptr = srcDCtx->hufTable; dstDCtx->rep[0] = srcDCtx->rep[0]; dstDCtx->rep[1] = srcDCtx->rep[1]; dstDCtx->rep[2] = srcDCtx->rep[2]; } } /*-************************************************************* * Decompression section ***************************************************************/ /* See compression format details in : doc/zstd_compression_format.md */ /** ZSTD_frameHeaderSize() : * srcSize must be >= ZSTD_frameHeaderSize_prefix. * @return : size of the Frame Header */ static size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize) { if (srcSize < ZSTD_frameHeaderSize_prefix) return ERROR(srcSize_wrong); { BYTE const fhd = ((const BYTE*)src)[4]; U32 const dictID= fhd & 3; U32 const singleSegment = (fhd >> 5) & 1; U32 const fcsId = fhd >> 6; return ZSTD_frameHeaderSize_prefix + !singleSegment + ZSTD_did_fieldSize[dictID] + ZSTD_fcs_fieldSize[fcsId] + (singleSegment && !fcsId); } } /** ZSTD_getFrameParams() : * decode Frame Header, or require larger `srcSize`. * @return : 0, `fparamsPtr` is correctly filled, * >0, `srcSize` is too small, result is expected `srcSize`, * or an error code, which can be tested using ZSTD_isError() */ size_t ZSTD_getFrameParams(ZSTD_frameParams* fparamsPtr, const void* src, size_t srcSize) { const BYTE* ip = (const BYTE*)src; if (srcSize < ZSTD_frameHeaderSize_prefix) return ZSTD_frameHeaderSize_prefix; if (MEM_readLE32(src) != ZSTD_MAGICNUMBER) { if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) { if (srcSize < ZSTD_skippableHeaderSize) return ZSTD_skippableHeaderSize; /* magic number + skippable frame length */ memset(fparamsPtr, 0, sizeof(*fparamsPtr)); fparamsPtr->frameContentSize = MEM_readLE32((const char *)src + 4); fparamsPtr->windowSize = 0; /* windowSize==0 means a frame is skippable */ return 0; } return ERROR(prefix_unknown); } /* ensure there is enough `srcSize` to fully read/decode frame header */ { size_t const fhsize = ZSTD_frameHeaderSize(src, srcSize); if (srcSize < fhsize) return fhsize; } { BYTE const fhdByte = ip[4]; size_t pos = 5; U32 const dictIDSizeCode = fhdByte&3; U32 const checksumFlag = (fhdByte>>2)&1; U32 const singleSegment = (fhdByte>>5)&1; U32 const fcsID = fhdByte>>6; U32 const windowSizeMax = 1U << ZSTD_WINDOWLOG_MAX; U32 windowSize = 0; U32 dictID = 0; U64 frameContentSize = 0; if ((fhdByte & 0x08) != 0) return ERROR(frameParameter_unsupported); /* reserved bits, which must be zero */ if (!singleSegment) { BYTE const wlByte = ip[pos++]; U32 const windowLog = (wlByte >> 3) + ZSTD_WINDOWLOG_ABSOLUTEMIN; if (windowLog > ZSTD_WINDOWLOG_MAX) return ERROR(frameParameter_windowTooLarge); /* avoids issue with 1 << windowLog */ windowSize = (1U << windowLog); windowSize += (windowSize >> 3) * (wlByte&7); } switch(dictIDSizeCode) { default: /* impossible */ 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: /* impossible */ 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 (!windowSize) windowSize = (U32)frameContentSize; if (windowSize > windowSizeMax) return ERROR(frameParameter_windowTooLarge); fparamsPtr->frameContentSize = frameContentSize; fparamsPtr->windowSize = windowSize; fparamsPtr->dictID = dictID; fparamsPtr->checksumFlag = checksumFlag; } return 0; } /** ZSTD_getDecompressedSize() : * compatible with legacy mode * @return : decompressed size if known, 0 otherwise note : 0 can mean any of the following : - decompressed size is not present within 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) { #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1) if (ZSTD_isLegacy(src, srcSize)) return ZSTD_getDecompressedSize_legacy(src, srcSize); #endif { ZSTD_frameParams fparams; size_t const frResult = ZSTD_getFrameParams(&fparams, src, srcSize); if (frResult!=0) return 0; return fparams.frameContentSize; } } /** ZSTD_decodeFrameHeader() : * `headerSize` must be the size provided by ZSTD_frameHeaderSize(). * @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_getFrameParams(&(dctx->fParams), src, headerSize); if (ZSTD_isError(result)) return result; /* invalid header */ if (result>0) return ERROR(srcSize_wrong); /* headerSize too small */ if (dctx->fParams.dictID && (dctx->dictID != dctx->fParams.dictID)) return ERROR(dictionary_wrong); if (dctx->fParams.checksumFlag) XXH64_reset(&dctx->xxhState, 0); return 0; } typedef struct { blockType_e blockType; U32 lastBlock; U32 origSize; } blockProperties_t; /*! ZSTD_getcBlockSize() : * Provides the size of compressed block from block header `src` */ size_t ZSTD_getcBlockSize(const void* src, size_t srcSize, blockProperties_t* bpPtr) { if (srcSize < ZSTD_blockHeaderSize) return ERROR(srcSize_wrong); { U32 const cBlockHeader = MEM_readLE24(src); U32 const cSize = cBlockHeader >> 3; bpPtr->lastBlock = cBlockHeader & 1; bpPtr->blockType = (blockType_e)((cBlockHeader >> 1) & 3); bpPtr->origSize = cSize; /* only useful for RLE */ if (bpPtr->blockType == bt_rle) return 1; if (bpPtr->blockType == bt_reserved) return ERROR(corruption_detected); return cSize; } } static size_t ZSTD_copyRawBlock(void* dst, size_t dstCapacity, const void* src, size_t srcSize) { if (srcSize > dstCapacity) return ERROR(dstSize_tooSmall); memcpy(dst, src, srcSize); return srcSize; } static size_t ZSTD_setRleBlock(void* dst, size_t dstCapacity, const void* src, size_t srcSize, size_t regenSize) { if (srcSize != 1) return ERROR(srcSize_wrong); if (regenSize > dstCapacity) return ERROR(dstSize_tooSmall); memset(dst, *(const BYTE*)src, regenSize); return regenSize; } /*! ZSTD_decodeLiteralsBlock() : @return : nb of bytes read from src (< srcSize ) */ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx, const void* src, size_t srcSize) /* note : srcSize < BLOCKSIZE */ { if (srcSize < MIN_CBLOCK_SIZE) return ERROR(corruption_detected); { const BYTE* const istart = (const BYTE*) src; symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3); switch(litEncType) { case set_repeat: if (dctx->litEntropy==0) return ERROR(dictionary_corrupted); /* fall-through */ case set_compressed: if (srcSize < 5) return ERROR(corruption_detected); /* srcSize >= MIN_CBLOCK_SIZE == 3; here we need up to 5 for case 3 */ { size_t lhSize, litSize, litCSize; U32 singleStream=0; U32 const lhlCode = (istart[0] >> 2) & 3; U32 const lhc = MEM_readLE32(istart); switch(lhlCode) { case 0: case 1: default: /* note : default is impossible, since lhlCode into [0..3] */ /* 2 - 2 - 10 - 10 */ singleStream = !lhlCode; lhSize = 3; litSize = (lhc >> 4) & 0x3FF; litCSize = (lhc >> 14) & 0x3FF; break; case 2: /* 2 - 2 - 14 - 14 */ lhSize = 4; litSize = (lhc >> 4) & 0x3FFF; litCSize = lhc >> 18; break; case 3: /* 2 - 2 - 18 - 18 */ lhSize = 5; litSize = (lhc >> 4) & 0x3FFFF; litCSize = (lhc >> 22) + (istart[4] << 10); break; } if (litSize > ZSTD_BLOCKSIZE_ABSOLUTEMAX) return ERROR(corruption_detected); if (litCSize + lhSize > srcSize) return ERROR(corruption_detected); if (HUF_isError((litEncType==set_repeat) ? ( singleStream ? HUF_decompress1X_usingDTable(dctx->litBuffer, litSize, istart+lhSize, litCSize, dctx->HUFptr) : HUF_decompress4X_usingDTable(dctx->litBuffer, litSize, istart+lhSize, litCSize, dctx->HUFptr) ) : ( singleStream ? HUF_decompress1X2_DCtx(dctx->hufTable, dctx->litBuffer, litSize, istart+lhSize, litCSize) : HUF_decompress4X_hufOnly (dctx->hufTable, dctx->litBuffer, litSize, istart+lhSize, litCSize)) )) return ERROR(corruption_detected); dctx->litPtr = dctx->litBuffer; dctx->litBufSize = ZSTD_BLOCKSIZE_ABSOLUTEMAX+WILDCOPY_OVERLENGTH; dctx->litSize = litSize; dctx->litEntropy = 1; if (litEncType==set_compressed) dctx->HUFptr = dctx->hufTable; return litCSize + lhSize; } case set_basic: { size_t litSize, lhSize; U32 const lhlCode = ((istart[0]) >> 2) & 3; switch(lhlCode) { case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */ lhSize = 1; litSize = istart[0] >> 3; break; case 1: lhSize = 2; litSize = MEM_readLE16(istart) >> 4; break; case 3: lhSize = 3; litSize = MEM_readLE24(istart) >> 4; break; } if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) { /* risk reading beyond src buffer with wildcopy */ if (litSize+lhSize > srcSize) return ERROR(corruption_detected); memcpy(dctx->litBuffer, istart+lhSize, litSize); dctx->litPtr = dctx->litBuffer; dctx->litBufSize = ZSTD_BLOCKSIZE_ABSOLUTEMAX+8; dctx->litSize = litSize; return lhSize+litSize; } /* direct reference into compressed stream */ dctx->litPtr = istart+lhSize; dctx->litBufSize = srcSize-lhSize; dctx->litSize = litSize; return lhSize+litSize; } case set_rle: { U32 const lhlCode = ((istart[0]) >> 2) & 3; size_t litSize, lhSize; switch(lhlCode) { case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */ lhSize = 1; litSize = istart[0] >> 3; break; case 1: lhSize = 2; litSize = MEM_readLE16(istart) >> 4; break; case 3: lhSize = 3; litSize = MEM_readLE24(istart) >> 4; if (srcSize<4) return ERROR(corruption_detected); /* srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4 */ break; } if (litSize > ZSTD_BLOCKSIZE_ABSOLUTEMAX) return ERROR(corruption_detected); memset(dctx->litBuffer, istart[lhSize], litSize); dctx->litPtr = dctx->litBuffer; dctx->litBufSize = ZSTD_BLOCKSIZE_ABSOLUTEMAX+WILDCOPY_OVERLENGTH; dctx->litSize = litSize; return lhSize+1; } default: return ERROR(corruption_detected); /* impossible */ } } } typedef union { FSE_decode_t realData; U32 alignedBy4; } FSE_decode_t4; static const FSE_decode_t4 LL_defaultDTable[(1<<LL_DEFAULTNORMLOG)+1] = { { { LL_DEFAULTNORMLOG, 1, 1 } }, /* header : tableLog, fastMode, fastMode */ { { 0, 0, 4 } }, /* 0 : base, symbol, bits */ { { 16, 0, 4 } }, { { 32, 1, 5 } }, { { 0, 3, 5 } }, { { 0, 4, 5 } }, { { 0, 6, 5 } }, { { 0, 7, 5 } }, { { 0, 9, 5 } }, { { 0, 10, 5 } }, { { 0, 12, 5 } }, { { 0, 14, 6 } }, { { 0, 16, 5 } }, { { 0, 18, 5 } }, { { 0, 19, 5 } }, { { 0, 21, 5 } }, { { 0, 22, 5 } }, { { 0, 24, 5 } }, { { 32, 25, 5 } }, { { 0, 26, 5 } }, { { 0, 27, 6 } }, { { 0, 29, 6 } }, { { 0, 31, 6 } }, { { 32, 0, 4 } }, { { 0, 1, 4 } }, { { 0, 2, 5 } }, { { 32, 4, 5 } }, { { 0, 5, 5 } }, { { 32, 7, 5 } }, { { 0, 8, 5 } }, { { 32, 10, 5 } }, { { 0, 11, 5 } }, { { 0, 13, 6 } }, { { 32, 16, 5 } }, { { 0, 17, 5 } }, { { 32, 19, 5 } }, { { 0, 20, 5 } }, { { 32, 22, 5 } }, { { 0, 23, 5 } }, { { 0, 25, 4 } }, { { 16, 25, 4 } }, { { 32, 26, 5 } }, { { 0, 28, 6 } }, { { 0, 30, 6 } }, { { 48, 0, 4 } }, { { 16, 1, 4 } }, { { 32, 2, 5 } }, { { 32, 3, 5 } }, { { 32, 5, 5 } }, { { 32, 6, 5 } }, { { 32, 8, 5 } }, { { 32, 9, 5 } }, { { 32, 11, 5 } }, { { 32, 12, 5 } }, { { 0, 15, 6 } }, { { 32, 17, 5 } }, { { 32, 18, 5 } }, { { 32, 20, 5 } }, { { 32, 21, 5 } }, { { 32, 23, 5 } }, { { 32, 24, 5 } }, { { 0, 35, 6 } }, { { 0, 34, 6 } }, { { 0, 33, 6 } }, { { 0, 32, 6 } }, }; /* LL_defaultDTable */ static const FSE_decode_t4 ML_defaultDTable[(1<<ML_DEFAULTNORMLOG)+1] = { { { ML_DEFAULTNORMLOG, 1, 1 } }, /* header : tableLog, fastMode, fastMode */ { { 0, 0, 6 } }, /* 0 : base, symbol, bits */ { { 0, 1, 4 } }, { { 32, 2, 5 } }, { { 0, 3, 5 } }, { { 0, 5, 5 } }, { { 0, 6, 5 } }, { { 0, 8, 5 } }, { { 0, 10, 6 } }, { { 0, 13, 6 } }, { { 0, 16, 6 } }, { { 0, 19, 6 } }, { { 0, 22, 6 } }, { { 0, 25, 6 } }, { { 0, 28, 6 } }, { { 0, 31, 6 } }, { { 0, 33, 6 } }, { { 0, 35, 6 } }, { { 0, 37, 6 } }, { { 0, 39, 6 } }, { { 0, 41, 6 } }, { { 0, 43, 6 } }, { { 0, 45, 6 } }, { { 16, 1, 4 } }, { { 0, 2, 4 } }, { { 32, 3, 5 } }, { { 0, 4, 5 } }, { { 32, 6, 5 } }, { { 0, 7, 5 } }, { { 0, 9, 6 } }, { { 0, 12, 6 } }, { { 0, 15, 6 } }, { { 0, 18, 6 } }, { { 0, 21, 6 } }, { { 0, 24, 6 } }, { { 0, 27, 6 } }, { { 0, 30, 6 } }, { { 0, 32, 6 } }, { { 0, 34, 6 } }, { { 0, 36, 6 } }, { { 0, 38, 6 } }, { { 0, 40, 6 } }, { { 0, 42, 6 } }, { { 0, 44, 6 } }, { { 32, 1, 4 } }, { { 48, 1, 4 } }, { { 16, 2, 4 } }, { { 32, 4, 5 } }, { { 32, 5, 5 } }, { { 32, 7, 5 } }, { { 32, 8, 5 } }, { { 0, 11, 6 } }, { { 0, 14, 6 } }, { { 0, 17, 6 } }, { { 0, 20, 6 } }, { { 0, 23, 6 } }, { { 0, 26, 6 } }, { { 0, 29, 6 } }, { { 0, 52, 6 } }, { { 0, 51, 6 } }, { { 0, 50, 6 } }, { { 0, 49, 6 } }, { { 0, 48, 6 } }, { { 0, 47, 6 } }, { { 0, 46, 6 } }, }; /* ML_defaultDTable */ static const FSE_decode_t4 OF_defaultDTable[(1<<OF_DEFAULTNORMLOG)+1] = { { { OF_DEFAULTNORMLOG, 1, 1 } }, /* header : tableLog, fastMode, fastMode */ { { 0, 0, 5 } }, /* 0 : base, symbol, bits */ { { 0, 6, 4 } }, { { 0, 9, 5 } }, { { 0, 15, 5 } }, { { 0, 21, 5 } }, { { 0, 3, 5 } }, { { 0, 7, 4 } }, { { 0, 12, 5 } }, { { 0, 18, 5 } }, { { 0, 23, 5 } }, { { 0, 5, 5 } }, { { 0, 8, 4 } }, { { 0, 14, 5 } }, { { 0, 20, 5 } }, { { 0, 2, 5 } }, { { 16, 7, 4 } }, { { 0, 11, 5 } }, { { 0, 17, 5 } }, { { 0, 22, 5 } }, { { 0, 4, 5 } }, { { 16, 8, 4 } }, { { 0, 13, 5 } }, { { 0, 19, 5 } }, { { 0, 1, 5 } }, { { 16, 6, 4 } }, { { 0, 10, 5 } }, { { 0, 16, 5 } }, { { 0, 28, 5 } }, { { 0, 27, 5 } }, { { 0, 26, 5 } }, { { 0, 25, 5 } }, { { 0, 24, 5 } }, }; /* OF_defaultDTable */ /*! ZSTD_buildSeqTable() : @return : nb bytes read from src, or an error code if it fails, testable with ZSTD_isError() */ static size_t ZSTD_buildSeqTable(FSE_DTable* DTableSpace, const FSE_DTable** DTablePtr, symbolEncodingType_e type, U32 max, U32 maxLog, const void* src, size_t srcSize, const FSE_decode_t4* defaultTable, U32 flagRepeatTable) { const void* const tmpPtr = defaultTable; /* bypass strict aliasing */ switch(type) { case set_rle : if (!srcSize) return ERROR(srcSize_wrong); if ( (*(const BYTE*)src) > max) return ERROR(corruption_detected); FSE_buildDTable_rle(DTableSpace, *(const BYTE*)src); *DTablePtr = DTableSpace; return 1; case set_basic : *DTablePtr = (const FSE_DTable*)tmpPtr; return 0; case set_repeat: if (!flagRepeatTable) return ERROR(corruption_detected); return 0; default : /* impossible */ case set_compressed : { U32 tableLog; S16 norm[MaxSeq+1]; size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize); if (FSE_isError(headerSize)) return ERROR(corruption_detected); if (tableLog > maxLog) return ERROR(corruption_detected); FSE_buildDTable(DTableSpace, norm, max, tableLog); *DTablePtr = DTableSpace; return headerSize; } } } size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr, const void* src, size_t srcSize) { const BYTE* const istart = (const BYTE* const)src; const BYTE* const iend = istart + srcSize; const BYTE* ip = istart; /* check */ if (srcSize < MIN_SEQUENCES_SIZE) return ERROR(srcSize_wrong); /* SeqHead */ { int nbSeq = *ip++; if (!nbSeq) { *nbSeqPtr=0; return 1; } if (nbSeq > 0x7F) { if (nbSeq == 0xFF) { if (ip+2 > iend) return ERROR(srcSize_wrong); nbSeq = MEM_readLE16(ip) + LONGNBSEQ, ip+=2; } else { if (ip >= iend) return ERROR(srcSize_wrong); nbSeq = ((nbSeq-0x80)<<8) + *ip++; } } *nbSeqPtr = nbSeq; } /* FSE table descriptors */ if (ip+4 > iend) return ERROR(srcSize_wrong); /* minimum possible size */ { symbolEncodingType_e const LLtype = (symbolEncodingType_e)(*ip >> 6); symbolEncodingType_e const OFtype = (symbolEncodingType_e)((*ip >> 4) & 3); symbolEncodingType_e const MLtype = (symbolEncodingType_e)((*ip >> 2) & 3); ip++; /* Build DTables */ { size_t const llhSize = ZSTD_buildSeqTable(dctx->LLTable, &dctx->LLTptr, LLtype, MaxLL, LLFSELog, ip, iend-ip, LL_defaultDTable, dctx->fseEntropy); if (ZSTD_isError(llhSize)) return ERROR(corruption_detected); ip += llhSize; } { size_t const ofhSize = ZSTD_buildSeqTable(dctx->OFTable, &dctx->OFTptr, OFtype, MaxOff, OffFSELog, ip, iend-ip, OF_defaultDTable, dctx->fseEntropy); if (ZSTD_isError(ofhSize)) return ERROR(corruption_detected); ip += ofhSize; } { size_t const mlhSize = ZSTD_buildSeqTable(dctx->MLTable, &dctx->MLTptr, MLtype, MaxML, MLFSELog, ip, iend-ip, ML_defaultDTable, dctx->fseEntropy); if (ZSTD_isError(mlhSize)) return ERROR(corruption_detected); ip += mlhSize; } } return ip-istart; } typedef struct { size_t litLength; size_t matchLength; size_t offset; } seq_t; typedef struct { BIT_DStream_t DStream; FSE_DState_t stateLL; FSE_DState_t stateOffb; FSE_DState_t stateML; size_t prevOffset[ZSTD_REP_NUM]; } seqState_t; static seq_t ZSTD_decodeSequence(seqState_t* seqState) { seq_t seq; U32 const llCode = FSE_peekSymbol(&seqState->stateLL); U32 const mlCode = FSE_peekSymbol(&seqState->stateML); U32 const ofCode = FSE_peekSymbol(&seqState->stateOffb); /* <= maxOff, by table construction */ U32 const llBits = LL_bits[llCode]; U32 const mlBits = ML_bits[mlCode]; U32 const ofBits = ofCode; U32 const totalBits = llBits+mlBits+ofBits; static const U32 LL_base[MaxLL+1] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 20, 22, 24, 28, 32, 40, 48, 64, 0x80, 0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000, 0x8000, 0x10000 }; static const U32 ML_base[MaxML+1] = { 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 39, 41, 43, 47, 51, 59, 67, 83, 99, 0x83, 0x103, 0x203, 0x403, 0x803, 0x1003, 0x2003, 0x4003, 0x8003, 0x10003 }; static const U32 OF_base[MaxOff+1] = { 0, 1, 1, 5, 0xD, 0x1D, 0x3D, 0x7D, 0xFD, 0x1FD, 0x3FD, 0x7FD, 0xFFD, 0x1FFD, 0x3FFD, 0x7FFD, 0xFFFD, 0x1FFFD, 0x3FFFD, 0x7FFFD, 0xFFFFD, 0x1FFFFD, 0x3FFFFD, 0x7FFFFD, 0xFFFFFD, 0x1FFFFFD, 0x3FFFFFD, 0x7FFFFFD, 0xFFFFFFD }; /* sequence */ { size_t offset; if (!ofCode) offset = 0; else { offset = OF_base[ofCode] + BIT_readBits(&seqState->DStream, ofBits); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */ if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); } if (ofCode <= 1) { offset += (llCode==0); if (offset) { size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset]; temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */ if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1]; seqState->prevOffset[1] = seqState->prevOffset[0]; seqState->prevOffset[0] = offset = temp; } else { offset = seqState->prevOffset[0]; } } else { seqState->prevOffset[2] = seqState->prevOffset[1]; seqState->prevOffset[1] = seqState->prevOffset[0]; seqState->prevOffset[0] = offset; } seq.offset = offset; } seq.matchLength = ML_base[mlCode] + ((mlCode>31) ? BIT_readBits(&seqState->DStream, mlBits) : 0); /* <= 16 bits */ if (MEM_32bits() && (mlBits+llBits>24)) BIT_reloadDStream(&seqState->DStream); seq.litLength = LL_base[llCode] + ((llCode>15) ? BIT_readBits(&seqState->DStream, llBits) : 0); /* <= 16 bits */ if (MEM_32bits() || (totalBits > 64 - 7 - (LLFSELog+MLFSELog+OffFSELog)) ) BIT_reloadDStream(&seqState->DStream); /* ANS state update */ FSE_updateState(&seqState->stateLL, &seqState->DStream); /* <= 9 bits */ FSE_updateState(&seqState->stateML, &seqState->DStream); /* <= 9 bits */ if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ FSE_updateState(&seqState->stateOffb, &seqState->DStream); /* <= 8 bits */ return seq; } FORCE_NOINLINE size_t ZSTD_execSequenceLast7(BYTE* op, BYTE* const oend, seq_t sequence, const BYTE** litPtr, const BYTE* const litLimit_w, const BYTE* const base, const BYTE* const vBase, const BYTE* const dictEnd) { BYTE* const oLitEnd = op + sequence.litLength; size_t const sequenceLength = sequence.litLength + sequence.matchLength; BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */ BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; const BYTE* const iLitEnd = *litPtr + sequence.litLength; const BYTE* match = oLitEnd - sequence.offset; /* check */ if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */ if (iLitEnd > litLimit_w) return ERROR(corruption_detected); /* over-read beyond lit buffer */ if (oLitEnd <= oend_w) return ERROR(GENERIC); /* Precondition */ /* copy literals */ if (op < oend_w) { ZSTD_wildcopy(op, *litPtr, oend_w - op); *litPtr += oend_w - op; op = oend_w; } while (op < oLitEnd) *op++ = *(*litPtr)++; /* copy Match */ if (sequence.offset > (size_t)(oLitEnd - base)) { /* offset beyond prefix */ if (sequence.offset > (size_t)(oLitEnd - vBase)) return ERROR(corruption_detected); match = dictEnd - (base-match); if (match + sequence.matchLength <= dictEnd) { memmove(oLitEnd, match, sequence.matchLength); return sequenceLength; } /* span extDict & currentPrefixSegment */ { size_t const length1 = dictEnd - match; memmove(oLitEnd, match, length1); op = oLitEnd + length1; sequence.matchLength -= length1; match = base; } } while (op < oMatchEnd) *op++ = *match++; return sequenceLength; } FORCE_INLINE size_t ZSTD_execSequence(BYTE* op, BYTE* const oend, seq_t sequence, const BYTE** litPtr, const BYTE* const litLimit_w, const BYTE* const base, const BYTE* const vBase, const BYTE* const dictEnd) { BYTE* const oLitEnd = op + sequence.litLength; size_t const sequenceLength = sequence.litLength + sequence.matchLength; BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */ BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; const BYTE* const iLitEnd = *litPtr + sequence.litLength; const BYTE* match = oLitEnd - sequence.offset; /* check */ if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */ if (iLitEnd > litLimit_w) return ERROR(corruption_detected); /* over-read beyond lit buffer */ if (oLitEnd>oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit_w, base, vBase, dictEnd); /* copy Literals */ ZSTD_copy8(op, *litPtr); if (sequence.litLength > 8) ZSTD_wildcopy(op+8, (*litPtr)+8, sequence.litLength - 8); /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */ op = oLitEnd; *litPtr = iLitEnd; /* update for next sequence */ /* copy Match */ if (sequence.offset > (size_t)(oLitEnd - base)) { /* offset beyond prefix */ if (sequence.offset > (size_t)(oLitEnd - vBase)) return ERROR(corruption_detected); match = dictEnd - (base-match); if (match + sequence.matchLength <= dictEnd) { memmove(oLitEnd, match, sequence.matchLength); return sequenceLength; } /* span extDict & currentPrefixSegment */ { size_t const length1 = dictEnd - match; memmove(oLitEnd, match, length1); op = oLitEnd + length1; sequence.matchLength -= length1; match = base; if (op > oend_w) { U32 i; for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i]; return sequenceLength; } } } /* Requirement: op <= oend_w */ /* match within prefix */ if (sequence.offset < 8) { /* close range match, overlap */ static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */ static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* substracted */ int const sub2 = dec64table[sequence.offset]; op[0] = match[0]; op[1] = match[1]; op[2] = match[2]; op[3] = match[3]; match += dec32table[sequence.offset]; ZSTD_copy4(op+4, match); match -= sub2; } else { ZSTD_copy8(op, match); } op += 8; match += 8; if (oMatchEnd > oend-(16-MINMATCH)) { if (op < oend_w) { ZSTD_wildcopy(op, match, oend_w - op); match += oend_w - op; op = oend_w; } while (op < oMatchEnd) *op++ = *match++; } else { ZSTD_wildcopy(op, match, sequence.matchLength-8); /* works even if matchLength < 8 */ } return sequenceLength; } static size_t ZSTD_decompressSequences( ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, const void* seqStart, size_t seqSize) { const BYTE* ip = (const BYTE*)seqStart; const BYTE* const iend = ip + seqSize; BYTE* const ostart = (BYTE* const)dst; BYTE* const oend = ostart + maxDstSize; BYTE* op = ostart; const BYTE* litPtr = dctx->litPtr; const BYTE* const litLimit_w = litPtr + dctx->litBufSize - WILDCOPY_OVERLENGTH; const BYTE* const litEnd = litPtr + dctx->litSize; const BYTE* const base = (const BYTE*) (dctx->base); const BYTE* const vBase = (const BYTE*) (dctx->vBase); const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd); int nbSeq; /* Build Decoding Tables */ { size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, seqSize); if (ZSTD_isError(seqHSize)) return seqHSize; ip += seqHSize; } /* Regen sequences */ if (nbSeq) { seqState_t seqState; dctx->fseEntropy = 1; { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->rep[i]; } CHECK_E(BIT_initDStream(&seqState.DStream, ip, iend-ip), corruption_detected); FSE_initDState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr); FSE_initDState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr); FSE_initDState(&seqState.stateML, &seqState.DStream, dctx->MLTptr); for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; ) { nbSeq--; { seq_t const sequence = ZSTD_decodeSequence(&seqState); size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litLimit_w, base, vBase, dictEnd); if (ZSTD_isError(oneSeqSize)) return oneSeqSize; op += oneSeqSize; } } /* check if reached exact end */ if (nbSeq) return ERROR(corruption_detected); /* save reps for next block */ { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->rep[i] = (U32)(seqState.prevOffset[i]); } } /* last literal segment */ { size_t const lastLLSize = litEnd - litPtr; if (lastLLSize > (size_t)(oend-op)) return ERROR(dstSize_tooSmall); memcpy(op, litPtr, lastLLSize); op += lastLLSize; } return op-ostart; } static void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst) { if (dst != dctx->previousDstEnd) { /* not contiguous */ dctx->dictEnd = dctx->previousDstEnd; dctx->vBase = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->base)); dctx->base = dst; dctx->previousDstEnd = dst; } } static size_t ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize) { /* blockType == blockCompressed */ const BYTE* ip = (const BYTE*)src; if (srcSize >= ZSTD_BLOCKSIZE_ABSOLUTEMAX) return ERROR(srcSize_wrong); /* Decode literals sub-block */ { size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize); if (ZSTD_isError(litCSize)) return litCSize; ip += litCSize; srcSize -= litCSize; } return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize); } size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize) { size_t dSize; ZSTD_checkContinuity(dctx, dst); dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize); dctx->previousDstEnd = (char*)dst + dSize; return dSize; } /** ZSTD_insertBlock() : insert `src` block into `dctx` history. Useful to track uncompressed blocks. */ ZSTDLIB_API size_t ZSTD_insertBlock(ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize) { ZSTD_checkContinuity(dctx, blockStart); dctx->previousDstEnd = (const char*)blockStart + blockSize; return blockSize; } size_t ZSTD_generateNxBytes(void* dst, size_t dstCapacity, BYTE byte, size_t length) { if (length > dstCapacity) return ERROR(dstSize_tooSmall); memset(dst, byte, length); return length; } /*! ZSTD_decompressFrame() : * `dctx` must be properly initialized */ static size_t ZSTD_decompressFrame(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize) { const BYTE* ip = (const BYTE*)src; BYTE* const ostart = (BYTE* const)dst; BYTE* const oend = ostart + dstCapacity; BYTE* op = ostart; size_t remainingSize = srcSize; /* check */ if (srcSize < ZSTD_frameHeaderSize_min+ZSTD_blockHeaderSize) return ERROR(srcSize_wrong); /* Frame Header */ { size_t const frameHeaderSize = ZSTD_frameHeaderSize(src, ZSTD_frameHeaderSize_prefix); if (ZSTD_isError(frameHeaderSize)) return frameHeaderSize; if (srcSize < frameHeaderSize+ZSTD_blockHeaderSize) return ERROR(srcSize_wrong); CHECK_F(ZSTD_decodeFrameHeader(dctx, src, frameHeaderSize)); ip += frameHeaderSize; remainingSize -= frameHeaderSize; } /* Loop on each block */ while (1) { size_t decodedSize; blockProperties_t blockProperties; size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSize, &blockProperties); if (ZSTD_isError(cBlockSize)) return cBlockSize; ip += ZSTD_blockHeaderSize; remainingSize -= ZSTD_blockHeaderSize; if (cBlockSize > remainingSize) return ERROR(srcSize_wrong); switch(blockProperties.blockType) { case bt_compressed: decodedSize = ZSTD_decompressBlock_internal(dctx, op, oend-op, ip, cBlockSize); break; case bt_raw : decodedSize = ZSTD_copyRawBlock(op, oend-op, ip, cBlockSize); break; case bt_rle : decodedSize = ZSTD_generateNxBytes(op, oend-op, *ip, blockProperties.origSize); break; case bt_reserved : default: return ERROR(corruption_detected); } if (ZSTD_isError(decodedSize)) return decodedSize; if (dctx->fParams.checksumFlag) XXH64_update(&dctx->xxhState, op, decodedSize); op += decodedSize; ip += cBlockSize; remainingSize -= cBlockSize; if (blockProperties.lastBlock) break; } if (dctx->fParams.checksumFlag) { /* Frame content checksum verification */ U32 const checkCalc = (U32)XXH64_digest(&dctx->xxhState); U32 checkRead; if (remainingSize<4) return ERROR(checksum_wrong); checkRead = MEM_readLE32(ip); if (checkRead != checkCalc) return ERROR(checksum_wrong); remainingSize -= 4; } if (remainingSize) return ERROR(srcSize_wrong); return op-ostart; } size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, const void* dict, size_t dictSize) { #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1) if (ZSTD_isLegacy(src, srcSize)) return ZSTD_decompressLegacy(dst, dstCapacity, src, srcSize, dict, dictSize); #endif ZSTD_decompressBegin_usingDict(dctx, dict, dictSize); ZSTD_checkContinuity(dctx, dst); return ZSTD_decompressFrame(dctx, dst, dstCapacity, src, srcSize); } size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize) { return ZSTD_decompress_usingDict(dctx, dst, dstCapacity, src, srcSize, NULL, 0); } size_t ZSTD_decompress(void* dst, size_t dstCapacity, const void* src, size_t srcSize) { #if defined(ZSTD_HEAPMODE) && (ZSTD_HEAPMODE==1) size_t regenSize; ZSTD_DCtx* const dctx = ZSTD_createDCtx(); if (dctx==NULL) return ERROR(memory_allocation); regenSize = ZSTD_decompressDCtx(dctx, dst, dstCapacity, src, srcSize); ZSTD_freeDCtx(dctx); return regenSize; #else /* stack mode */ ZSTD_DCtx dctx; return ZSTD_decompressDCtx(&dctx, dst, dstCapacity, src, srcSize); #endif } /*-************************************** * Advanced Streaming Decompression API * Bufferless and synchronous ****************************************/ size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx) { return dctx->expected; } ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx) { switch(dctx->stage) { default: /* should not happen */ case ZSTDds_getFrameHeaderSize: case ZSTDds_decodeFrameHeader: return ZSTDnit_frameHeader; case ZSTDds_decodeBlockHeader: return ZSTDnit_blockHeader; case ZSTDds_decompressBlock: return ZSTDnit_block; case ZSTDds_decompressLastBlock: return ZSTDnit_lastBlock; case ZSTDds_checkChecksum: return ZSTDnit_checksum; case ZSTDds_decodeSkippableHeader: case ZSTDds_skipFrame: return ZSTDnit_skippableFrame; } } int ZSTD_isSkipFrame(ZSTD_DCtx* dctx) { return dctx->stage == ZSTDds_skipFrame; } /* for zbuff */ /** ZSTD_decompressContinue() : * @return : nb of bytes generated into `dst` (necessarily <= `dstCapacity) * or an error code, which can be tested using ZSTD_isError() */ size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize) { /* Sanity check */ if (srcSize != dctx->expected) return ERROR(srcSize_wrong); if (dstCapacity) ZSTD_checkContinuity(dctx, dst); switch (dctx->stage) { case ZSTDds_getFrameHeaderSize : if (srcSize != ZSTD_frameHeaderSize_prefix) return ERROR(srcSize_wrong); /* impossible */ if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) { /* skippable frame */ memcpy(dctx->headerBuffer, src, ZSTD_frameHeaderSize_prefix); dctx->expected = ZSTD_skippableHeaderSize - ZSTD_frameHeaderSize_prefix; /* magic number + skippable frame length */ dctx->stage = ZSTDds_decodeSkippableHeader; return 0; } dctx->headerSize = ZSTD_frameHeaderSize(src, ZSTD_frameHeaderSize_prefix); if (ZSTD_isError(dctx->headerSize)) return dctx->headerSize; memcpy(dctx->headerBuffer, src, ZSTD_frameHeaderSize_prefix); if (dctx->headerSize > ZSTD_frameHeaderSize_prefix) { dctx->expected = dctx->headerSize - ZSTD_frameHeaderSize_prefix; dctx->stage = ZSTDds_decodeFrameHeader; return 0; } dctx->expected = 0; /* not necessary to copy more */ case ZSTDds_decodeFrameHeader: memcpy(dctx->headerBuffer + ZSTD_frameHeaderSize_prefix, src, dctx->expected); CHECK_F(ZSTD_decodeFrameHeader(dctx, dctx->headerBuffer, dctx->headerSize)); dctx->expected = ZSTD_blockHeaderSize; dctx->stage = ZSTDds_decodeBlockHeader; return 0; case ZSTDds_decodeBlockHeader: { blockProperties_t bp; size_t const cBlockSize = ZSTD_getcBlockSize(src, ZSTD_blockHeaderSize, &bp); if (ZSTD_isError(cBlockSize)) return cBlockSize; dctx->expected = cBlockSize; dctx->bType = bp.blockType; dctx->rleSize = bp.origSize; if (cBlockSize) { dctx->stage = bp.lastBlock ? ZSTDds_decompressLastBlock : ZSTDds_decompressBlock; return 0; } /* empty block */ if (bp.lastBlock) { if (dctx->fParams.checksumFlag) { dctx->expected = 4; dctx->stage = ZSTDds_checkChecksum; } else { dctx->expected = 0; /* end of frame */ dctx->stage = ZSTDds_getFrameHeaderSize; } } else { dctx->expected = 3; /* go directly to next header */ dctx->stage = ZSTDds_decodeBlockHeader; } return 0; } case ZSTDds_decompressLastBlock: case ZSTDds_decompressBlock: { size_t rSize; switch(dctx->bType) { case bt_compressed: rSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize); break; case bt_raw : rSize = ZSTD_copyRawBlock(dst, dstCapacity, src, srcSize); break; case bt_rle : rSize = ZSTD_setRleBlock(dst, dstCapacity, src, srcSize, dctx->rleSize); break; case bt_reserved : /* should never happen */ default: return ERROR(corruption_detected); } if (ZSTD_isError(rSize)) return rSize; if (dctx->fParams.checksumFlag) XXH64_update(&dctx->xxhState, dst, rSize); if (dctx->stage == ZSTDds_decompressLastBlock) { /* end of frame */ if (dctx->fParams.checksumFlag) { /* another round for frame checksum */ dctx->expected = 4; dctx->stage = ZSTDds_checkChecksum; } else { dctx->expected = 0; /* ends here */ dctx->stage = ZSTDds_getFrameHeaderSize; } } else { dctx->stage = ZSTDds_decodeBlockHeader; dctx->expected = ZSTD_blockHeaderSize; dctx->previousDstEnd = (char*)dst + rSize; } return rSize; } case ZSTDds_checkChecksum: { U32 const h32 = (U32)XXH64_digest(&dctx->xxhState); U32 const check32 = MEM_readLE32(src); /* srcSize == 4, guaranteed by dctx->expected */ if (check32 != h32) return ERROR(checksum_wrong); dctx->expected = 0; dctx->stage = ZSTDds_getFrameHeaderSize; return 0; } case ZSTDds_decodeSkippableHeader: { memcpy(dctx->headerBuffer + ZSTD_frameHeaderSize_prefix, src, dctx->expected); dctx->expected = MEM_readLE32(dctx->headerBuffer + 4); dctx->stage = ZSTDds_skipFrame; return 0; } case ZSTDds_skipFrame: { dctx->expected = 0; dctx->stage = ZSTDds_getFrameHeaderSize; return 0; } default: return ERROR(GENERIC); /* impossible */ } } static size_t ZSTD_refDictContent(ZSTD_DCtx* dctx, const void* dict, size_t dictSize) { dctx->dictEnd = dctx->previousDstEnd; dctx->vBase = (const char*)dict - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->base)); dctx->base = dict; dctx->previousDstEnd = (const char*)dict + dictSize; return 0; } static size_t ZSTD_loadEntropy(ZSTD_DCtx* dctx, const void* const dict, size_t const dictSize) { const BYTE* dictPtr = (const BYTE*)dict; const BYTE* const dictEnd = dictPtr + dictSize; { size_t const hSize = HUF_readDTableX4(dctx->hufTable, dict, dictSize); if (HUF_isError(hSize)) return ERROR(dictionary_corrupted); dictPtr += hSize; } { short offcodeNCount[MaxOff+1]; U32 offcodeMaxValue=MaxOff, offcodeLog; size_t const offcodeHeaderSize = FSE_readNCount(offcodeNCount, &offcodeMaxValue, &offcodeLog, dictPtr, dictEnd-dictPtr); if (FSE_isError(offcodeHeaderSize)) return ERROR(dictionary_corrupted); if (offcodeLog > OffFSELog) return ERROR(dictionary_corrupted); CHECK_E(FSE_buildDTable(dctx->OFTable, offcodeNCount, offcodeMaxValue, offcodeLog), dictionary_corrupted); dictPtr += offcodeHeaderSize; } { short matchlengthNCount[MaxML+1]; unsigned matchlengthMaxValue = MaxML, matchlengthLog; size_t const matchlengthHeaderSize = FSE_readNCount(matchlengthNCount, &matchlengthMaxValue, &matchlengthLog, dictPtr, dictEnd-dictPtr); if (FSE_isError(matchlengthHeaderSize)) return ERROR(dictionary_corrupted); if (matchlengthLog > MLFSELog) return ERROR(dictionary_corrupted); CHECK_E(FSE_buildDTable(dctx->MLTable, matchlengthNCount, matchlengthMaxValue, matchlengthLog), dictionary_corrupted); dictPtr += matchlengthHeaderSize; } { short litlengthNCount[MaxLL+1]; unsigned litlengthMaxValue = MaxLL, litlengthLog; size_t const litlengthHeaderSize = FSE_readNCount(litlengthNCount, &litlengthMaxValue, &litlengthLog, dictPtr, dictEnd-dictPtr); if (FSE_isError(litlengthHeaderSize)) return ERROR(dictionary_corrupted); if (litlengthLog > LLFSELog) return ERROR(dictionary_corrupted); CHECK_E(FSE_buildDTable(dctx->LLTable, litlengthNCount, litlengthMaxValue, litlengthLog), dictionary_corrupted); dictPtr += litlengthHeaderSize; } if (dictPtr+12 > dictEnd) return ERROR(dictionary_corrupted); dctx->rep[0] = MEM_readLE32(dictPtr+0); if (dctx->rep[0] >= dictSize) return ERROR(dictionary_corrupted); dctx->rep[1] = MEM_readLE32(dictPtr+4); if (dctx->rep[1] >= dictSize) return ERROR(dictionary_corrupted); dctx->rep[2] = MEM_readLE32(dictPtr+8); if (dctx->rep[2] >= dictSize) return ERROR(dictionary_corrupted); dictPtr += 12; dctx->litEntropy = dctx->fseEntropy = 1; return dictPtr - (const BYTE*)dict; } static size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize) { if (dictSize < 8) return ZSTD_refDictContent(dctx, dict, dictSize); { U32 const magic = MEM_readLE32(dict); if (magic != ZSTD_DICT_MAGIC) { return ZSTD_refDictContent(dctx, dict, dictSize); /* pure content mode */ } } dctx->dictID = MEM_readLE32((const char*)dict + 4); /* load entropy tables */ dict = (const char*)dict + 8; dictSize -= 8; { size_t const eSize = ZSTD_loadEntropy(dctx, dict, dictSize); if (ZSTD_isError(eSize)) return ERROR(dictionary_corrupted); dict = (const char*)dict + eSize; dictSize -= eSize; } /* reference dictionary content */ return ZSTD_refDictContent(dctx, dict, dictSize); } size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize) { CHECK_F(ZSTD_decompressBegin(dctx)); if (dict && dictSize) CHECK_E(ZSTD_decompress_insertDictionary(dctx, dict, dictSize), dictionary_corrupted); return 0; } /* ====== ZSTD_DDict ====== */ struct ZSTD_DDict_s { void* dict; size_t dictSize; ZSTD_DCtx* refContext; }; /* typedef'd to ZSTD_DDict within "zstd.h" */ ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, ZSTD_customMem customMem) { if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem; if (!customMem.customAlloc || !customMem.customFree) return NULL; { ZSTD_DDict* const ddict = (ZSTD_DDict*) ZSTD_malloc(sizeof(ZSTD_DDict), customMem); void* const dictContent = ZSTD_malloc(dictSize, customMem); ZSTD_DCtx* const dctx = ZSTD_createDCtx_advanced(customMem); if (!dictContent || !ddict || !dctx) { ZSTD_free(dictContent, customMem); ZSTD_free(ddict, customMem); ZSTD_free(dctx, customMem); return NULL; } if (dictSize) { memcpy(dictContent, dict, dictSize); } { size_t const errorCode = ZSTD_decompressBegin_usingDict(dctx, dictContent, dictSize); if (ZSTD_isError(errorCode)) { ZSTD_free(dictContent, customMem); ZSTD_free(ddict, customMem); ZSTD_free(dctx, customMem); return NULL; } } ddict->dict = dictContent; ddict->dictSize = dictSize; ddict->refContext = dctx; return ddict; } } /*! ZSTD_createDDict() : * Create a digested dictionary, ready to start decompression without startup delay. * `dict` can be released after `ZSTD_DDict` creation */ ZSTD_DDict* ZSTD_createDDict(const void* dict, size_t dictSize) { ZSTD_customMem const allocator = { NULL, NULL, NULL }; return ZSTD_createDDict_advanced(dict, dictSize, allocator); } size_t ZSTD_freeDDict(ZSTD_DDict* ddict) { if (ddict==NULL) return 0; /* support free on NULL */ { ZSTD_customMem const cMem = ddict->refContext->customMem; ZSTD_freeDCtx(ddict->refContext); ZSTD_free(ddict->dict, cMem); ZSTD_free(ddict, cMem); return 0; } } size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict) { if (ddict==NULL) return 0; /* support sizeof on NULL */ return sizeof(*ddict) + sizeof(ddict->refContext) + ddict->dictSize; } /*! ZSTD_decompress_usingDDict() : * Decompression using a pre-digested Dictionary * Use dictionary without significant overhead. */ size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, const ZSTD_DDict* ddict) { #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1) if (ZSTD_isLegacy(src, srcSize)) return ZSTD_decompressLegacy(dst, dstCapacity, src, srcSize, ddict->dict, ddict->dictSize); #endif ZSTD_refDCtx(dctx, ddict->refContext); ZSTD_checkContinuity(dctx, dst); return ZSTD_decompressFrame(dctx, dst, dstCapacity, src, srcSize); } /*===================================== * Streaming decompression *====================================*/ typedef enum { zdss_init, zdss_loadHeader, zdss_read, zdss_load, zdss_flush } ZSTD_dStreamStage; /* *** Resource management *** */ struct ZSTD_DStream_s { ZSTD_DCtx* dctx; ZSTD_DDict* ddictLocal; const ZSTD_DDict* ddict; ZSTD_frameParams fParams; ZSTD_dStreamStage stage; char* inBuff; size_t inBuffSize; size_t inPos; size_t maxWindowSize; char* outBuff; size_t outBuffSize; size_t outStart; size_t outEnd; size_t blockSize; BYTE headerBuffer[ZSTD_FRAMEHEADERSIZE_MAX]; /* tmp buffer to store frame header */ size_t lhSize; ZSTD_customMem customMem; void* legacyContext; U32 previousLegacyVersion; U32 legacyVersion; U32 hostageByte; }; /* typedef'd to ZSTD_DStream within "zstd.h" */ ZSTD_DStream* ZSTD_createDStream(void) { return ZSTD_createDStream_advanced(defaultCustomMem); } ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem) { ZSTD_DStream* zds; if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem; if (!customMem.customAlloc || !customMem.customFree) return NULL; zds = (ZSTD_DStream*) ZSTD_malloc(sizeof(ZSTD_DStream), customMem); if (zds==NULL) return NULL; memset(zds, 0, sizeof(ZSTD_DStream)); memcpy(&zds->customMem, &customMem, sizeof(ZSTD_customMem)); zds->dctx = ZSTD_createDCtx_advanced(customMem); if (zds->dctx == NULL) { ZSTD_freeDStream(zds); return NULL; } zds->stage = zdss_init; zds->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT; return zds; } size_t ZSTD_freeDStream(ZSTD_DStream* zds) { if (zds==NULL) return 0; /* support free on null */ { ZSTD_customMem const cMem = zds->customMem; ZSTD_freeDCtx(zds->dctx); ZSTD_freeDDict(zds->ddictLocal); ZSTD_free(zds->inBuff, cMem); ZSTD_free(zds->outBuff, cMem); #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1) if (zds->legacyContext) ZSTD_freeLegacyStreamContext(zds->legacyContext, zds->previousLegacyVersion); #endif ZSTD_free(zds, cMem); return 0; } } /* *** Initialization *** */ size_t ZSTD_DStreamInSize(void) { return ZSTD_BLOCKSIZE_ABSOLUTEMAX + ZSTD_blockHeaderSize; } size_t ZSTD_DStreamOutSize(void) { return ZSTD_BLOCKSIZE_ABSOLUTEMAX; } size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize) { zds->stage = zdss_loadHeader; zds->lhSize = zds->inPos = zds->outStart = zds->outEnd = 0; ZSTD_freeDDict(zds->ddictLocal); if (dict) { zds->ddictLocal = ZSTD_createDDict(dict, dictSize); if (zds->ddictLocal == NULL) return ERROR(memory_allocation); } else zds->ddictLocal = NULL; zds->ddict = zds->ddictLocal; zds->legacyVersion = 0; zds->hostageByte = 0; return ZSTD_frameHeaderSize_prefix; } size_t ZSTD_initDStream(ZSTD_DStream* zds) { return ZSTD_initDStream_usingDict(zds, NULL, 0); } size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict) /**< note : ddict will just be referenced, and must outlive decompression session */ { size_t const initResult = ZSTD_initDStream(zds); zds->ddict = ddict; return initResult; } size_t ZSTD_resetDStream(ZSTD_DStream* zds) { zds->stage = zdss_loadHeader; zds->lhSize = zds->inPos = zds->outStart = zds->outEnd = 0; zds->legacyVersion = 0; zds->hostageByte = 0; return ZSTD_frameHeaderSize_prefix; } size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue) { switch(paramType) { default : return ERROR(parameter_unknown); case ZSTDdsp_maxWindowSize : zds->maxWindowSize = paramValue ? paramValue : (U32)(-1); break; } return 0; } size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds) { if (zds==NULL) return 0; /* support sizeof on NULL */ return sizeof(*zds) + ZSTD_sizeof_DCtx(zds->dctx) + ZSTD_sizeof_DDict(zds->ddictLocal) + zds->inBuffSize + zds->outBuffSize; } /* ***** Decompression ***** */ MEM_STATIC size_t ZSTD_limitCopy(void* dst, size_t dstCapacity, const void* src, size_t srcSize) { size_t const length = MIN(dstCapacity, srcSize); memcpy(dst, src, length); return length; } size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input) { const char* const istart = (const char*)(input->src) + input->pos; const char* const iend = (const char*)(input->src) + input->size; const char* ip = istart; char* const ostart = (char*)(output->dst) + output->pos; char* const oend = (char*)(output->dst) + output->size; char* op = ostart; U32 someMoreWork = 1; #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1) if (zds->legacyVersion) return ZSTD_decompressLegacyStream(zds->legacyContext, zds->legacyVersion, output, input); #endif while (someMoreWork) { switch(zds->stage) { case zdss_init : return ERROR(init_missing); case zdss_loadHeader : { size_t const hSize = ZSTD_getFrameParams(&zds->fParams, zds->headerBuffer, zds->lhSize); if (ZSTD_isError(hSize)) #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1) { U32 const legacyVersion = ZSTD_isLegacy(istart, iend-istart); if (legacyVersion) { const void* const dict = zds->ddict ? zds->ddict->dict : NULL; size_t const dictSize = zds->ddict ? zds->ddict->dictSize : 0; CHECK_F(ZSTD_initLegacyStream(&zds->legacyContext, zds->previousLegacyVersion, legacyVersion, dict, dictSize)); zds->legacyVersion = zds->previousLegacyVersion = legacyVersion; return ZSTD_decompressLegacyStream(zds->legacyContext, zds->legacyVersion, output, input); } else { return hSize; /* error */ } } #else return hSize; #endif if (hSize != 0) { /* need more input */ size_t const toLoad = hSize - zds->lhSize; /* if hSize!=0, hSize > zds->lhSize */ if (toLoad > (size_t)(iend-ip)) { /* not enough input to load full header */ memcpy(zds->headerBuffer + zds->lhSize, ip, iend-ip); zds->lhSize += iend-ip; input->pos = input->size; return (MAX(ZSTD_frameHeaderSize_min, hSize) - zds->lhSize) + ZSTD_blockHeaderSize; /* remaining header bytes + next block header */ } memcpy(zds->headerBuffer + zds->lhSize, ip, toLoad); zds->lhSize = hSize; ip += toLoad; break; } } /* Consume header */ { const ZSTD_DCtx* refContext = zds->ddict ? zds->ddict->refContext : NULL; ZSTD_refDCtx(zds->dctx, refContext); } { size_t const h1Size = ZSTD_nextSrcSizeToDecompress(zds->dctx); /* == ZSTD_frameHeaderSize_prefix */ CHECK_F(ZSTD_decompressContinue(zds->dctx, NULL, 0, zds->headerBuffer, h1Size)); { size_t const h2Size = ZSTD_nextSrcSizeToDecompress(zds->dctx); CHECK_F(ZSTD_decompressContinue(zds->dctx, NULL, 0, zds->headerBuffer+h1Size, h2Size)); } } zds->fParams.windowSize = MAX(zds->fParams.windowSize, 1U << ZSTD_WINDOWLOG_ABSOLUTEMIN); if (zds->fParams.windowSize > zds->maxWindowSize) return ERROR(frameParameter_windowTooLarge); /* Adapt buffer sizes to frame header instructions */ { size_t const blockSize = MIN(zds->fParams.windowSize, ZSTD_BLOCKSIZE_ABSOLUTEMAX); size_t const neededOutSize = zds->fParams.windowSize + blockSize; zds->blockSize = blockSize; if (zds->inBuffSize < blockSize) { ZSTD_free(zds->inBuff, zds->customMem); zds->inBuffSize = blockSize; zds->inBuff = (char*)ZSTD_malloc(blockSize, zds->customMem); if (zds->inBuff == NULL) return ERROR(memory_allocation); } if (zds->outBuffSize < neededOutSize) { ZSTD_free(zds->outBuff, zds->customMem); zds->outBuffSize = neededOutSize; zds->outBuff = (char*)ZSTD_malloc(neededOutSize, zds->customMem); if (zds->outBuff == NULL) return ERROR(memory_allocation); } } zds->stage = zdss_read; /* pass-through */ case zdss_read: { size_t const neededInSize = ZSTD_nextSrcSizeToDecompress(zds->dctx); if (neededInSize==0) { /* end of frame */ zds->stage = zdss_init; someMoreWork = 0; break; } if ((size_t)(iend-ip) >= neededInSize) { /* decode directly from src */ const int isSkipFrame = ZSTD_isSkipFrame(zds->dctx); size_t const decodedSize = ZSTD_decompressContinue(zds->dctx, zds->outBuff + zds->outStart, (isSkipFrame ? 0 : zds->outBuffSize - zds->outStart), ip, neededInSize); if (ZSTD_isError(decodedSize)) return decodedSize; ip += neededInSize; if (!decodedSize && !isSkipFrame) break; /* this was just a header */ zds->outEnd = zds->outStart + decodedSize; zds->stage = zdss_flush; break; } if (ip==iend) { someMoreWork = 0; break; } /* no more input */ zds->stage = zdss_load; /* pass-through */ } case zdss_load: { size_t const neededInSize = ZSTD_nextSrcSizeToDecompress(zds->dctx); size_t const toLoad = neededInSize - zds->inPos; /* should always be <= remaining space within inBuff */ size_t loadedSize; if (toLoad > zds->inBuffSize - zds->inPos) return ERROR(corruption_detected); /* should never happen */ loadedSize = ZSTD_limitCopy(zds->inBuff + zds->inPos, toLoad, ip, iend-ip); ip += loadedSize; zds->inPos += loadedSize; if (loadedSize < toLoad) { someMoreWork = 0; break; } /* not enough input, wait for more */ /* decode loaded input */ { const int isSkipFrame = ZSTD_isSkipFrame(zds->dctx); size_t const decodedSize = ZSTD_decompressContinue(zds->dctx, zds->outBuff + zds->outStart, zds->outBuffSize - zds->outStart, zds->inBuff, neededInSize); if (ZSTD_isError(decodedSize)) return decodedSize; zds->inPos = 0; /* input is consumed */ if (!decodedSize && !isSkipFrame) { zds->stage = zdss_read; break; } /* this was just a header */ zds->outEnd = zds->outStart + decodedSize; zds->stage = zdss_flush; /* pass-through */ } } case zdss_flush: { size_t const toFlushSize = zds->outEnd - zds->outStart; size_t const flushedSize = ZSTD_limitCopy(op, oend-op, zds->outBuff + zds->outStart, toFlushSize); op += flushedSize; zds->outStart += flushedSize; if (flushedSize == toFlushSize) { /* flush completed */ zds->stage = zdss_read; if (zds->outStart + zds->blockSize > zds->outBuffSize) zds->outStart = zds->outEnd = 0; break; } /* cannot complete flush */ someMoreWork = 0; break; } default: return ERROR(GENERIC); /* impossible */ } } /* result */ input->pos += (size_t)(ip-istart); output->pos += (size_t)(op-ostart); { size_t nextSrcSizeHint = ZSTD_nextSrcSizeToDecompress(zds->dctx); if (!nextSrcSizeHint) { /* frame fully decoded */ if (zds->outEnd == zds->outStart) { /* output fully flushed */ if (zds->hostageByte) { if (input->pos >= input->size) { zds->stage = zdss_read; return 1; } /* can't release hostage (not present) */ input->pos++; /* release hostage */ } return 0; } if (!zds->hostageByte) { /* output not fully flushed; keep last byte as hostage; will be released when all output is flushed */ input->pos--; /* note : pos > 0, otherwise, impossible to finish reading last block */ zds->hostageByte=1; } return 1; } nextSrcSizeHint += ZSTD_blockHeaderSize * (ZSTD_nextInputType(zds->dctx) == ZSTDnit_block); /* preload header of next block */ if (zds->inPos > nextSrcSizeHint) return ERROR(GENERIC); /* should never happen */ nextSrcSizeHint -= zds->inPos; /* already loaded*/ return nextSrcSizeHint; } }