1/* 2 * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc. 3 * All rights reserved. 4 * 5 * This source code is licensed under both the BSD-style license (found in the 6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 7 * in the COPYING file in the root directory of this source tree). 8 * You may select, at your option, one of the above-listed licenses. 9 */ 10 11/* zstd_decompress_block : 12 * this module takes care of decompressing _compressed_ block */ 13 14/*-******************************************************* 15* Dependencies 16*********************************************************/ 17#include <string.h> /* memcpy, memmove, memset */ 18#include "../common/compiler.h" /* prefetch */ 19#include "../common/cpu.h" /* bmi2 */ 20#include "../common/mem.h" /* low level memory routines */ 21#define FSE_STATIC_LINKING_ONLY 22#include "../common/fse.h" 23#define HUF_STATIC_LINKING_ONLY 24#include "../common/huf.h" 25#include "../common/zstd_internal.h" 26#include "zstd_decompress_internal.h" /* ZSTD_DCtx */ 27#include "zstd_ddict.h" /* ZSTD_DDictDictContent */ 28#include "zstd_decompress_block.h" 29 30/*_******************************************************* 31* Macros 32**********************************************************/ 33 34/* These two optional macros force the use one way or another of the two 35 * ZSTD_decompressSequences implementations. You can't force in both directions 36 * at the same time. 37 */ 38#if defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 39 defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 40#error "Cannot force the use of the short and the long ZSTD_decompressSequences variants!" 41#endif 42 43 44/*_******************************************************* 45* Memory operations 46**********************************************************/ 47static void ZSTD_copy4(void* dst, const void* src) { memcpy(dst, src, 4); } 48 49 50/*-************************************************************* 51 * Block decoding 52 ***************************************************************/ 53 54/*! ZSTD_getcBlockSize() : 55 * Provides the size of compressed block from block header `src` */ 56size_t ZSTD_getcBlockSize(const void* src, size_t srcSize, 57 blockProperties_t* bpPtr) 58{ 59 RETURN_ERROR_IF(srcSize < ZSTD_blockHeaderSize, srcSize_wrong, ""); 60 61 { U32 const cBlockHeader = MEM_readLE24(src); 62 U32 const cSize = cBlockHeader >> 3; 63 bpPtr->lastBlock = cBlockHeader & 1; 64 bpPtr->blockType = (blockType_e)((cBlockHeader >> 1) & 3); 65 bpPtr->origSize = cSize; /* only useful for RLE */ 66 if (bpPtr->blockType == bt_rle) return 1; 67 RETURN_ERROR_IF(bpPtr->blockType == bt_reserved, corruption_detected, ""); 68 return cSize; 69 } 70} 71 72 73/* Hidden declaration for fullbench */ 74size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx, 75 const void* src, size_t srcSize); 76/*! ZSTD_decodeLiteralsBlock() : 77 * @return : nb of bytes read from src (< srcSize ) 78 * note : symbol not declared but exposed for fullbench */ 79size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx, 80 const void* src, size_t srcSize) /* note : srcSize < BLOCKSIZE */ 81{ 82 DEBUGLOG(5, "ZSTD_decodeLiteralsBlock"); 83 RETURN_ERROR_IF(srcSize < MIN_CBLOCK_SIZE, corruption_detected, ""); 84 85 { const BYTE* const istart = (const BYTE*) src; 86 symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3); 87 88 switch(litEncType) 89 { 90 case set_repeat: 91 DEBUGLOG(5, "set_repeat flag : re-using stats from previous compressed literals block"); 92 RETURN_ERROR_IF(dctx->litEntropy==0, dictionary_corrupted, ""); 93 /* fall-through */ 94 95 case set_compressed: 96 RETURN_ERROR_IF(srcSize < 5, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need up to 5 for case 3"); 97 { size_t lhSize, litSize, litCSize; 98 U32 singleStream=0; 99 U32 const lhlCode = (istart[0] >> 2) & 3; 100 U32 const lhc = MEM_readLE32(istart); 101 size_t hufSuccess; 102 switch(lhlCode) 103 { 104 case 0: case 1: default: /* note : default is impossible, since lhlCode into [0..3] */ 105 /* 2 - 2 - 10 - 10 */ 106 singleStream = !lhlCode; 107 lhSize = 3; 108 litSize = (lhc >> 4) & 0x3FF; 109 litCSize = (lhc >> 14) & 0x3FF; 110 break; 111 case 2: 112 /* 2 - 2 - 14 - 14 */ 113 lhSize = 4; 114 litSize = (lhc >> 4) & 0x3FFF; 115 litCSize = lhc >> 18; 116 break; 117 case 3: 118 /* 2 - 2 - 18 - 18 */ 119 lhSize = 5; 120 litSize = (lhc >> 4) & 0x3FFFF; 121 litCSize = (lhc >> 22) + ((size_t)istart[4] << 10); 122 break; 123 } 124 RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, ""); 125 RETURN_ERROR_IF(litCSize + lhSize > srcSize, corruption_detected, ""); 126 127 /* prefetch huffman table if cold */ 128 if (dctx->ddictIsCold && (litSize > 768 /* heuristic */)) { 129 PREFETCH_AREA(dctx->HUFptr, sizeof(dctx->entropy.hufTable)); 130 } 131 132 if (litEncType==set_repeat) { 133 if (singleStream) { 134 hufSuccess = HUF_decompress1X_usingDTable_bmi2( 135 dctx->litBuffer, litSize, istart+lhSize, litCSize, 136 dctx->HUFptr, dctx->bmi2); 137 } else { 138 hufSuccess = HUF_decompress4X_usingDTable_bmi2( 139 dctx->litBuffer, litSize, istart+lhSize, litCSize, 140 dctx->HUFptr, dctx->bmi2); 141 } 142 } else { 143 if (singleStream) { 144#if defined(HUF_FORCE_DECOMPRESS_X2) 145 hufSuccess = HUF_decompress1X_DCtx_wksp( 146 dctx->entropy.hufTable, dctx->litBuffer, litSize, 147 istart+lhSize, litCSize, dctx->workspace, 148 sizeof(dctx->workspace)); 149#else 150 hufSuccess = HUF_decompress1X1_DCtx_wksp_bmi2( 151 dctx->entropy.hufTable, dctx->litBuffer, litSize, 152 istart+lhSize, litCSize, dctx->workspace, 153 sizeof(dctx->workspace), dctx->bmi2); 154#endif 155 } else { 156 hufSuccess = HUF_decompress4X_hufOnly_wksp_bmi2( 157 dctx->entropy.hufTable, dctx->litBuffer, litSize, 158 istart+lhSize, litCSize, dctx->workspace, 159 sizeof(dctx->workspace), dctx->bmi2); 160 } 161 } 162 163 RETURN_ERROR_IF(HUF_isError(hufSuccess), corruption_detected, ""); 164 165 dctx->litPtr = dctx->litBuffer; 166 dctx->litSize = litSize; 167 dctx->litEntropy = 1; 168 if (litEncType==set_compressed) dctx->HUFptr = dctx->entropy.hufTable; 169 memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH); 170 return litCSize + lhSize; 171 } 172 173 case set_basic: 174 { size_t litSize, lhSize; 175 U32 const lhlCode = ((istart[0]) >> 2) & 3; 176 switch(lhlCode) 177 { 178 case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */ 179 lhSize = 1; 180 litSize = istart[0] >> 3; 181 break; 182 case 1: 183 lhSize = 2; 184 litSize = MEM_readLE16(istart) >> 4; 185 break; 186 case 3: 187 lhSize = 3; 188 litSize = MEM_readLE24(istart) >> 4; 189 break; 190 } 191 192 if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) { /* risk reading beyond src buffer with wildcopy */ 193 RETURN_ERROR_IF(litSize+lhSize > srcSize, corruption_detected, ""); 194 memcpy(dctx->litBuffer, istart+lhSize, litSize); 195 dctx->litPtr = dctx->litBuffer; 196 dctx->litSize = litSize; 197 memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH); 198 return lhSize+litSize; 199 } 200 /* direct reference into compressed stream */ 201 dctx->litPtr = istart+lhSize; 202 dctx->litSize = litSize; 203 return lhSize+litSize; 204 } 205 206 case set_rle: 207 { U32 const lhlCode = ((istart[0]) >> 2) & 3; 208 size_t litSize, lhSize; 209 switch(lhlCode) 210 { 211 case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */ 212 lhSize = 1; 213 litSize = istart[0] >> 3; 214 break; 215 case 1: 216 lhSize = 2; 217 litSize = MEM_readLE16(istart) >> 4; 218 break; 219 case 3: 220 lhSize = 3; 221 litSize = MEM_readLE24(istart) >> 4; 222 RETURN_ERROR_IF(srcSize<4, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4"); 223 break; 224 } 225 RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, ""); 226 memset(dctx->litBuffer, istart[lhSize], litSize + WILDCOPY_OVERLENGTH); 227 dctx->litPtr = dctx->litBuffer; 228 dctx->litSize = litSize; 229 return lhSize+1; 230 } 231 default: 232 RETURN_ERROR(corruption_detected, "impossible"); 233 } 234 } 235} 236 237/* Default FSE distribution tables. 238 * These are pre-calculated FSE decoding tables using default distributions as defined in specification : 239 * https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#default-distributions 240 * They were generated programmatically with following method : 241 * - start from default distributions, present in /lib/common/zstd_internal.h 242 * - generate tables normally, using ZSTD_buildFSETable() 243 * - printout the content of tables 244 * - pretify output, report below, test with fuzzer to ensure it's correct */ 245 246/* Default FSE distribution table for Literal Lengths */ 247static const ZSTD_seqSymbol LL_defaultDTable[(1<<LL_DEFAULTNORMLOG)+1] = { 248 { 1, 1, 1, LL_DEFAULTNORMLOG}, /* header : fastMode, tableLog */ 249 /* nextState, nbAddBits, nbBits, baseVal */ 250 { 0, 0, 4, 0}, { 16, 0, 4, 0}, 251 { 32, 0, 5, 1}, { 0, 0, 5, 3}, 252 { 0, 0, 5, 4}, { 0, 0, 5, 6}, 253 { 0, 0, 5, 7}, { 0, 0, 5, 9}, 254 { 0, 0, 5, 10}, { 0, 0, 5, 12}, 255 { 0, 0, 6, 14}, { 0, 1, 5, 16}, 256 { 0, 1, 5, 20}, { 0, 1, 5, 22}, 257 { 0, 2, 5, 28}, { 0, 3, 5, 32}, 258 { 0, 4, 5, 48}, { 32, 6, 5, 64}, 259 { 0, 7, 5, 128}, { 0, 8, 6, 256}, 260 { 0, 10, 6, 1024}, { 0, 12, 6, 4096}, 261 { 32, 0, 4, 0}, { 0, 0, 4, 1}, 262 { 0, 0, 5, 2}, { 32, 0, 5, 4}, 263 { 0, 0, 5, 5}, { 32, 0, 5, 7}, 264 { 0, 0, 5, 8}, { 32, 0, 5, 10}, 265 { 0, 0, 5, 11}, { 0, 0, 6, 13}, 266 { 32, 1, 5, 16}, { 0, 1, 5, 18}, 267 { 32, 1, 5, 22}, { 0, 2, 5, 24}, 268 { 32, 3, 5, 32}, { 0, 3, 5, 40}, 269 { 0, 6, 4, 64}, { 16, 6, 4, 64}, 270 { 32, 7, 5, 128}, { 0, 9, 6, 512}, 271 { 0, 11, 6, 2048}, { 48, 0, 4, 0}, 272 { 16, 0, 4, 1}, { 32, 0, 5, 2}, 273 { 32, 0, 5, 3}, { 32, 0, 5, 5}, 274 { 32, 0, 5, 6}, { 32, 0, 5, 8}, 275 { 32, 0, 5, 9}, { 32, 0, 5, 11}, 276 { 32, 0, 5, 12}, { 0, 0, 6, 15}, 277 { 32, 1, 5, 18}, { 32, 1, 5, 20}, 278 { 32, 2, 5, 24}, { 32, 2, 5, 28}, 279 { 32, 3, 5, 40}, { 32, 4, 5, 48}, 280 { 0, 16, 6,65536}, { 0, 15, 6,32768}, 281 { 0, 14, 6,16384}, { 0, 13, 6, 8192}, 282}; /* LL_defaultDTable */ 283 284/* Default FSE distribution table for Offset Codes */ 285static const ZSTD_seqSymbol OF_defaultDTable[(1<<OF_DEFAULTNORMLOG)+1] = { 286 { 1, 1, 1, OF_DEFAULTNORMLOG}, /* header : fastMode, tableLog */ 287 /* nextState, nbAddBits, nbBits, baseVal */ 288 { 0, 0, 5, 0}, { 0, 6, 4, 61}, 289 { 0, 9, 5, 509}, { 0, 15, 5,32765}, 290 { 0, 21, 5,2097149}, { 0, 3, 5, 5}, 291 { 0, 7, 4, 125}, { 0, 12, 5, 4093}, 292 { 0, 18, 5,262141}, { 0, 23, 5,8388605}, 293 { 0, 5, 5, 29}, { 0, 8, 4, 253}, 294 { 0, 14, 5,16381}, { 0, 20, 5,1048573}, 295 { 0, 2, 5, 1}, { 16, 7, 4, 125}, 296 { 0, 11, 5, 2045}, { 0, 17, 5,131069}, 297 { 0, 22, 5,4194301}, { 0, 4, 5, 13}, 298 { 16, 8, 4, 253}, { 0, 13, 5, 8189}, 299 { 0, 19, 5,524285}, { 0, 1, 5, 1}, 300 { 16, 6, 4, 61}, { 0, 10, 5, 1021}, 301 { 0, 16, 5,65533}, { 0, 28, 5,268435453}, 302 { 0, 27, 5,134217725}, { 0, 26, 5,67108861}, 303 { 0, 25, 5,33554429}, { 0, 24, 5,16777213}, 304}; /* OF_defaultDTable */ 305 306 307/* Default FSE distribution table for Match Lengths */ 308static const ZSTD_seqSymbol ML_defaultDTable[(1<<ML_DEFAULTNORMLOG)+1] = { 309 { 1, 1, 1, ML_DEFAULTNORMLOG}, /* header : fastMode, tableLog */ 310 /* nextState, nbAddBits, nbBits, baseVal */ 311 { 0, 0, 6, 3}, { 0, 0, 4, 4}, 312 { 32, 0, 5, 5}, { 0, 0, 5, 6}, 313 { 0, 0, 5, 8}, { 0, 0, 5, 9}, 314 { 0, 0, 5, 11}, { 0, 0, 6, 13}, 315 { 0, 0, 6, 16}, { 0, 0, 6, 19}, 316 { 0, 0, 6, 22}, { 0, 0, 6, 25}, 317 { 0, 0, 6, 28}, { 0, 0, 6, 31}, 318 { 0, 0, 6, 34}, { 0, 1, 6, 37}, 319 { 0, 1, 6, 41}, { 0, 2, 6, 47}, 320 { 0, 3, 6, 59}, { 0, 4, 6, 83}, 321 { 0, 7, 6, 131}, { 0, 9, 6, 515}, 322 { 16, 0, 4, 4}, { 0, 0, 4, 5}, 323 { 32, 0, 5, 6}, { 0, 0, 5, 7}, 324 { 32, 0, 5, 9}, { 0, 0, 5, 10}, 325 { 0, 0, 6, 12}, { 0, 0, 6, 15}, 326 { 0, 0, 6, 18}, { 0, 0, 6, 21}, 327 { 0, 0, 6, 24}, { 0, 0, 6, 27}, 328 { 0, 0, 6, 30}, { 0, 0, 6, 33}, 329 { 0, 1, 6, 35}, { 0, 1, 6, 39}, 330 { 0, 2, 6, 43}, { 0, 3, 6, 51}, 331 { 0, 4, 6, 67}, { 0, 5, 6, 99}, 332 { 0, 8, 6, 259}, { 32, 0, 4, 4}, 333 { 48, 0, 4, 4}, { 16, 0, 4, 5}, 334 { 32, 0, 5, 7}, { 32, 0, 5, 8}, 335 { 32, 0, 5, 10}, { 32, 0, 5, 11}, 336 { 0, 0, 6, 14}, { 0, 0, 6, 17}, 337 { 0, 0, 6, 20}, { 0, 0, 6, 23}, 338 { 0, 0, 6, 26}, { 0, 0, 6, 29}, 339 { 0, 0, 6, 32}, { 0, 16, 6,65539}, 340 { 0, 15, 6,32771}, { 0, 14, 6,16387}, 341 { 0, 13, 6, 8195}, { 0, 12, 6, 4099}, 342 { 0, 11, 6, 2051}, { 0, 10, 6, 1027}, 343}; /* ML_defaultDTable */ 344 345 346static void ZSTD_buildSeqTable_rle(ZSTD_seqSymbol* dt, U32 baseValue, U32 nbAddBits) 347{ 348 void* ptr = dt; 349 ZSTD_seqSymbol_header* const DTableH = (ZSTD_seqSymbol_header*)ptr; 350 ZSTD_seqSymbol* const cell = dt + 1; 351 352 DTableH->tableLog = 0; 353 DTableH->fastMode = 0; 354 355 cell->nbBits = 0; 356 cell->nextState = 0; 357 assert(nbAddBits < 255); 358 cell->nbAdditionalBits = (BYTE)nbAddBits; 359 cell->baseValue = baseValue; 360} 361 362 363/* ZSTD_buildFSETable() : 364 * generate FSE decoding table for one symbol (ll, ml or off) 365 * cannot fail if input is valid => 366 * all inputs are presumed validated at this stage */ 367void 368ZSTD_buildFSETable(ZSTD_seqSymbol* dt, 369 const short* normalizedCounter, unsigned maxSymbolValue, 370 const U32* baseValue, const U32* nbAdditionalBits, 371 unsigned tableLog) 372{ 373 ZSTD_seqSymbol* const tableDecode = dt+1; 374 U16 symbolNext[MaxSeq+1]; 375 376 U32 const maxSV1 = maxSymbolValue + 1; 377 U32 const tableSize = 1 << tableLog; 378 U32 highThreshold = tableSize-1; 379 380 /* Sanity Checks */ 381 assert(maxSymbolValue <= MaxSeq); 382 assert(tableLog <= MaxFSELog); 383 384 /* Init, lay down lowprob symbols */ 385 { ZSTD_seqSymbol_header DTableH; 386 DTableH.tableLog = tableLog; 387 DTableH.fastMode = 1; 388 { S16 const largeLimit= (S16)(1 << (tableLog-1)); 389 U32 s; 390 for (s=0; s<maxSV1; s++) { 391 if (normalizedCounter[s]==-1) { 392 tableDecode[highThreshold--].baseValue = s; 393 symbolNext[s] = 1; 394 } else { 395 if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0; 396 assert(normalizedCounter[s]>=0); 397 symbolNext[s] = (U16)normalizedCounter[s]; 398 } } } 399 memcpy(dt, &DTableH, sizeof(DTableH)); 400 } 401 402 /* Spread symbols */ 403 { U32 const tableMask = tableSize-1; 404 U32 const step = FSE_TABLESTEP(tableSize); 405 U32 s, position = 0; 406 for (s=0; s<maxSV1; s++) { 407 int i; 408 for (i=0; i<normalizedCounter[s]; i++) { 409 tableDecode[position].baseValue = s; 410 position = (position + step) & tableMask; 411 while (position > highThreshold) position = (position + step) & tableMask; /* lowprob area */ 412 } } 413 assert(position == 0); /* position must reach all cells once, otherwise normalizedCounter is incorrect */ 414 } 415 416 /* Build Decoding table */ 417 { U32 u; 418 for (u=0; u<tableSize; u++) { 419 U32 const symbol = tableDecode[u].baseValue; 420 U32 const nextState = symbolNext[symbol]++; 421 tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) ); 422 tableDecode[u].nextState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize); 423 assert(nbAdditionalBits[symbol] < 255); 424 tableDecode[u].nbAdditionalBits = (BYTE)nbAdditionalBits[symbol]; 425 tableDecode[u].baseValue = baseValue[symbol]; 426 } } 427} 428 429 430/*! ZSTD_buildSeqTable() : 431 * @return : nb bytes read from src, 432 * or an error code if it fails */ 433static size_t ZSTD_buildSeqTable(ZSTD_seqSymbol* DTableSpace, const ZSTD_seqSymbol** DTablePtr, 434 symbolEncodingType_e type, unsigned max, U32 maxLog, 435 const void* src, size_t srcSize, 436 const U32* baseValue, const U32* nbAdditionalBits, 437 const ZSTD_seqSymbol* defaultTable, U32 flagRepeatTable, 438 int ddictIsCold, int nbSeq) 439{ 440 switch(type) 441 { 442 case set_rle : 443 RETURN_ERROR_IF(!srcSize, srcSize_wrong, ""); 444 RETURN_ERROR_IF((*(const BYTE*)src) > max, corruption_detected, ""); 445 { U32 const symbol = *(const BYTE*)src; 446 U32 const baseline = baseValue[symbol]; 447 U32 const nbBits = nbAdditionalBits[symbol]; 448 ZSTD_buildSeqTable_rle(DTableSpace, baseline, nbBits); 449 } 450 *DTablePtr = DTableSpace; 451 return 1; 452 case set_basic : 453 *DTablePtr = defaultTable; 454 return 0; 455 case set_repeat: 456 RETURN_ERROR_IF(!flagRepeatTable, corruption_detected, ""); 457 /* prefetch FSE table if used */ 458 if (ddictIsCold && (nbSeq > 24 /* heuristic */)) { 459 const void* const pStart = *DTablePtr; 460 size_t const pSize = sizeof(ZSTD_seqSymbol) * (SEQSYMBOL_TABLE_SIZE(maxLog)); 461 PREFETCH_AREA(pStart, pSize); 462 } 463 return 0; 464 case set_compressed : 465 { unsigned tableLog; 466 S16 norm[MaxSeq+1]; 467 size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize); 468 RETURN_ERROR_IF(FSE_isError(headerSize), corruption_detected, ""); 469 RETURN_ERROR_IF(tableLog > maxLog, corruption_detected, ""); 470 ZSTD_buildFSETable(DTableSpace, norm, max, baseValue, nbAdditionalBits, tableLog); 471 *DTablePtr = DTableSpace; 472 return headerSize; 473 } 474 default : 475 assert(0); 476 RETURN_ERROR(GENERIC, "impossible"); 477 } 478} 479 480size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr, 481 const void* src, size_t srcSize) 482{ 483 const BYTE* const istart = (const BYTE* const)src; 484 const BYTE* const iend = istart + srcSize; 485 const BYTE* ip = istart; 486 int nbSeq; 487 DEBUGLOG(5, "ZSTD_decodeSeqHeaders"); 488 489 /* check */ 490 RETURN_ERROR_IF(srcSize < MIN_SEQUENCES_SIZE, srcSize_wrong, ""); 491 492 /* SeqHead */ 493 nbSeq = *ip++; 494 if (!nbSeq) { 495 *nbSeqPtr=0; 496 RETURN_ERROR_IF(srcSize != 1, srcSize_wrong, ""); 497 return 1; 498 } 499 if (nbSeq > 0x7F) { 500 if (nbSeq == 0xFF) { 501 RETURN_ERROR_IF(ip+2 > iend, srcSize_wrong, ""); 502 nbSeq = MEM_readLE16(ip) + LONGNBSEQ, ip+=2; 503 } else { 504 RETURN_ERROR_IF(ip >= iend, srcSize_wrong, ""); 505 nbSeq = ((nbSeq-0x80)<<8) + *ip++; 506 } 507 } 508 *nbSeqPtr = nbSeq; 509 510 /* FSE table descriptors */ 511 RETURN_ERROR_IF(ip+1 > iend, srcSize_wrong, ""); /* minimum possible size: 1 byte for symbol encoding types */ 512 { symbolEncodingType_e const LLtype = (symbolEncodingType_e)(*ip >> 6); 513 symbolEncodingType_e const OFtype = (symbolEncodingType_e)((*ip >> 4) & 3); 514 symbolEncodingType_e const MLtype = (symbolEncodingType_e)((*ip >> 2) & 3); 515 ip++; 516 517 /* Build DTables */ 518 { size_t const llhSize = ZSTD_buildSeqTable(dctx->entropy.LLTable, &dctx->LLTptr, 519 LLtype, MaxLL, LLFSELog, 520 ip, iend-ip, 521 LL_base, LL_bits, 522 LL_defaultDTable, dctx->fseEntropy, 523 dctx->ddictIsCold, nbSeq); 524 RETURN_ERROR_IF(ZSTD_isError(llhSize), corruption_detected, "ZSTD_buildSeqTable failed"); 525 ip += llhSize; 526 } 527 528 { size_t const ofhSize = ZSTD_buildSeqTable(dctx->entropy.OFTable, &dctx->OFTptr, 529 OFtype, MaxOff, OffFSELog, 530 ip, iend-ip, 531 OF_base, OF_bits, 532 OF_defaultDTable, dctx->fseEntropy, 533 dctx->ddictIsCold, nbSeq); 534 RETURN_ERROR_IF(ZSTD_isError(ofhSize), corruption_detected, "ZSTD_buildSeqTable failed"); 535 ip += ofhSize; 536 } 537 538 { size_t const mlhSize = ZSTD_buildSeqTable(dctx->entropy.MLTable, &dctx->MLTptr, 539 MLtype, MaxML, MLFSELog, 540 ip, iend-ip, 541 ML_base, ML_bits, 542 ML_defaultDTable, dctx->fseEntropy, 543 dctx->ddictIsCold, nbSeq); 544 RETURN_ERROR_IF(ZSTD_isError(mlhSize), corruption_detected, "ZSTD_buildSeqTable failed"); 545 ip += mlhSize; 546 } 547 } 548 549 return ip-istart; 550} 551 552 553typedef struct { 554 size_t litLength; 555 size_t matchLength; 556 size_t offset; 557} seq_t; 558 559typedef struct { 560 size_t state; 561 const ZSTD_seqSymbol* table; 562} ZSTD_fseState; 563 564typedef struct { 565 BIT_DStream_t DStream; 566 ZSTD_fseState stateLL; 567 ZSTD_fseState stateOffb; 568 ZSTD_fseState stateML; 569 size_t prevOffset[ZSTD_REP_NUM]; 570} seqState_t; 571 572/*! ZSTD_overlapCopy8() : 573 * Copies 8 bytes from ip to op and updates op and ip where ip <= op. 574 * If the offset is < 8 then the offset is spread to at least 8 bytes. 575 * 576 * Precondition: *ip <= *op 577 * Postcondition: *op - *op >= 8 578 */ 579HINT_INLINE void ZSTD_overlapCopy8(BYTE** op, BYTE const** ip, size_t offset) { 580 assert(*ip <= *op); 581 if (offset < 8) { 582 /* close range match, overlap */ 583 static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */ 584 static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */ 585 int const sub2 = dec64table[offset]; 586 (*op)[0] = (*ip)[0]; 587 (*op)[1] = (*ip)[1]; 588 (*op)[2] = (*ip)[2]; 589 (*op)[3] = (*ip)[3]; 590 *ip += dec32table[offset]; 591 ZSTD_copy4(*op+4, *ip); 592 *ip -= sub2; 593 } else { 594 ZSTD_copy8(*op, *ip); 595 } 596 *ip += 8; 597 *op += 8; 598 assert(*op - *ip >= 8); 599} 600 601/*! ZSTD_safecopy() : 602 * Specialized version of memcpy() that is allowed to READ up to WILDCOPY_OVERLENGTH past the input buffer 603 * and write up to 16 bytes past oend_w (op >= oend_w is allowed). 604 * This function is only called in the uncommon case where the sequence is near the end of the block. It 605 * should be fast for a single long sequence, but can be slow for several short sequences. 606 * 607 * @param ovtype controls the overlap detection 608 * - ZSTD_no_overlap: The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart. 609 * - ZSTD_overlap_src_before_dst: The src and dst may overlap and may be any distance apart. 610 * The src buffer must be before the dst buffer. 611 */ 612static void ZSTD_safecopy(BYTE* op, BYTE* const oend_w, BYTE const* ip, ptrdiff_t length, ZSTD_overlap_e ovtype) { 613 ptrdiff_t const diff = op - ip; 614 BYTE* const oend = op + length; 615 616 assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8 || op >= oend_w)) || 617 (ovtype == ZSTD_overlap_src_before_dst && diff >= 0)); 618 619 if (length < 8) { 620 /* Handle short lengths. */ 621 while (op < oend) *op++ = *ip++; 622 return; 623 } 624 if (ovtype == ZSTD_overlap_src_before_dst) { 625 /* Copy 8 bytes and ensure the offset >= 8 when there can be overlap. */ 626 assert(length >= 8); 627 ZSTD_overlapCopy8(&op, &ip, diff); 628 assert(op - ip >= 8); 629 assert(op <= oend); 630 } 631 632 if (oend <= oend_w) { 633 /* No risk of overwrite. */ 634 ZSTD_wildcopy(op, ip, length, ovtype); 635 return; 636 } 637 if (op <= oend_w) { 638 /* Wildcopy until we get close to the end. */ 639 assert(oend > oend_w); 640 ZSTD_wildcopy(op, ip, oend_w - op, ovtype); 641 ip += oend_w - op; 642 op = oend_w; 643 } 644 /* Handle the leftovers. */ 645 while (op < oend) *op++ = *ip++; 646} 647 648/* ZSTD_execSequenceEnd(): 649 * This version handles cases that are near the end of the output buffer. It requires 650 * more careful checks to make sure there is no overflow. By separating out these hard 651 * and unlikely cases, we can speed up the common cases. 652 * 653 * NOTE: This function needs to be fast for a single long sequence, but doesn't need 654 * to be optimized for many small sequences, since those fall into ZSTD_execSequence(). 655 */ 656FORCE_NOINLINE 657size_t ZSTD_execSequenceEnd(BYTE* op, 658 BYTE* const oend, seq_t sequence, 659 const BYTE** litPtr, const BYTE* const litLimit, 660 const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd) 661{ 662 BYTE* const oLitEnd = op + sequence.litLength; 663 size_t const sequenceLength = sequence.litLength + sequence.matchLength; 664 const BYTE* const iLitEnd = *litPtr + sequence.litLength; 665 const BYTE* match = oLitEnd - sequence.offset; 666 BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; 667 668 /* bounds checks : careful of address space overflow in 32-bit mode */ 669 RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer"); 670 RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer"); 671 assert(op < op + sequenceLength); 672 assert(oLitEnd < op + sequenceLength); 673 674 /* copy literals */ 675 ZSTD_safecopy(op, oend_w, *litPtr, sequence.litLength, ZSTD_no_overlap); 676 op = oLitEnd; 677 *litPtr = iLitEnd; 678 679 /* copy Match */ 680 if (sequence.offset > (size_t)(oLitEnd - prefixStart)) { 681 /* offset beyond prefix */ 682 RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, ""); 683 match = dictEnd - (prefixStart-match); 684 if (match + sequence.matchLength <= dictEnd) { 685 memmove(oLitEnd, match, sequence.matchLength); 686 return sequenceLength; 687 } 688 /* span extDict & currentPrefixSegment */ 689 { size_t const length1 = dictEnd - match; 690 memmove(oLitEnd, match, length1); 691 op = oLitEnd + length1; 692 sequence.matchLength -= length1; 693 match = prefixStart; 694 } } 695 ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst); 696 return sequenceLength; 697} 698 699HINT_INLINE 700size_t ZSTD_execSequence(BYTE* op, 701 BYTE* const oend, seq_t sequence, 702 const BYTE** litPtr, const BYTE* const litLimit, 703 const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd) 704{ 705 BYTE* const oLitEnd = op + sequence.litLength; 706 size_t const sequenceLength = sequence.litLength + sequence.matchLength; 707 BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */ 708 BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; /* risk : address space underflow on oend=NULL */ 709 const BYTE* const iLitEnd = *litPtr + sequence.litLength; 710 const BYTE* match = oLitEnd - sequence.offset; 711 712 assert(op != NULL /* Precondition */); 713 assert(oend_w < oend /* No underflow */); 714 /* Handle edge cases in a slow path: 715 * - Read beyond end of literals 716 * - Match end is within WILDCOPY_OVERLIMIT of oend 717 * - 32-bit mode and the match length overflows 718 */ 719 if (UNLIKELY( 720 iLitEnd > litLimit || 721 oMatchEnd > oend_w || 722 (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH))) 723 return ZSTD_execSequenceEnd(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd); 724 725 /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */ 726 assert(op <= oLitEnd /* No overflow */); 727 assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */); 728 assert(oMatchEnd <= oend /* No underflow */); 729 assert(iLitEnd <= litLimit /* Literal length is in bounds */); 730 assert(oLitEnd <= oend_w /* Can wildcopy literals */); 731 assert(oMatchEnd <= oend_w /* Can wildcopy matches */); 732 733 /* Copy Literals: 734 * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9. 735 * We likely don't need the full 32-byte wildcopy. 736 */ 737 assert(WILDCOPY_OVERLENGTH >= 16); 738 ZSTD_copy16(op, (*litPtr)); 739 if (UNLIKELY(sequence.litLength > 16)) { 740 ZSTD_wildcopy(op+16, (*litPtr)+16, sequence.litLength-16, ZSTD_no_overlap); 741 } 742 op = oLitEnd; 743 *litPtr = iLitEnd; /* update for next sequence */ 744 745 /* Copy Match */ 746 if (sequence.offset > (size_t)(oLitEnd - prefixStart)) { 747 /* offset beyond prefix -> go into extDict */ 748 RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, ""); 749 match = dictEnd + (match - prefixStart); 750 if (match + sequence.matchLength <= dictEnd) { 751 memmove(oLitEnd, match, sequence.matchLength); 752 return sequenceLength; 753 } 754 /* span extDict & currentPrefixSegment */ 755 { size_t const length1 = dictEnd - match; 756 memmove(oLitEnd, match, length1); 757 op = oLitEnd + length1; 758 sequence.matchLength -= length1; 759 match = prefixStart; 760 } } 761 /* Match within prefix of 1 or more bytes */ 762 assert(op <= oMatchEnd); 763 assert(oMatchEnd <= oend_w); 764 assert(match >= prefixStart); 765 assert(sequence.matchLength >= 1); 766 767 /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy 768 * without overlap checking. 769 */ 770 if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) { 771 /* We bet on a full wildcopy for matches, since we expect matches to be 772 * longer than literals (in general). In silesia, ~10% of matches are longer 773 * than 16 bytes. 774 */ 775 ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap); 776 return sequenceLength; 777 } 778 assert(sequence.offset < WILDCOPY_VECLEN); 779 780 /* Copy 8 bytes and spread the offset to be >= 8. */ 781 ZSTD_overlapCopy8(&op, &match, sequence.offset); 782 783 /* If the match length is > 8 bytes, then continue with the wildcopy. */ 784 if (sequence.matchLength > 8) { 785 assert(op < oMatchEnd); 786 ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst); 787 } 788 return sequenceLength; 789} 790 791static void 792ZSTD_initFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, const ZSTD_seqSymbol* dt) 793{ 794 const void* ptr = dt; 795 const ZSTD_seqSymbol_header* const DTableH = (const ZSTD_seqSymbol_header*)ptr; 796 DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog); 797 DEBUGLOG(6, "ZSTD_initFseState : val=%u using %u bits", 798 (U32)DStatePtr->state, DTableH->tableLog); 799 BIT_reloadDStream(bitD); 800 DStatePtr->table = dt + 1; 801} 802 803FORCE_INLINE_TEMPLATE void 804ZSTD_updateFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD) 805{ 806 ZSTD_seqSymbol const DInfo = DStatePtr->table[DStatePtr->state]; 807 U32 const nbBits = DInfo.nbBits; 808 size_t const lowBits = BIT_readBits(bitD, nbBits); 809 DStatePtr->state = DInfo.nextState + lowBits; 810} 811 812FORCE_INLINE_TEMPLATE void 813ZSTD_updateFseStateWithDInfo(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, ZSTD_seqSymbol const DInfo) 814{ 815 U32 const nbBits = DInfo.nbBits; 816 size_t const lowBits = BIT_readBits(bitD, nbBits); 817 DStatePtr->state = DInfo.nextState + lowBits; 818} 819 820/* We need to add at most (ZSTD_WINDOWLOG_MAX_32 - 1) bits to read the maximum 821 * offset bits. But we can only read at most (STREAM_ACCUMULATOR_MIN_32 - 1) 822 * bits before reloading. This value is the maximum number of bytes we read 823 * after reloading when we are decoding long offsets. 824 */ 825#define LONG_OFFSETS_MAX_EXTRA_BITS_32 \ 826 (ZSTD_WINDOWLOG_MAX_32 > STREAM_ACCUMULATOR_MIN_32 \ 827 ? ZSTD_WINDOWLOG_MAX_32 - STREAM_ACCUMULATOR_MIN_32 \ 828 : 0) 829 830typedef enum { ZSTD_lo_isRegularOffset, ZSTD_lo_isLongOffset=1 } ZSTD_longOffset_e; 831 832FORCE_INLINE_TEMPLATE seq_t 833ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets) 834{ 835 seq_t seq; 836 ZSTD_seqSymbol const llDInfo = seqState->stateLL.table[seqState->stateLL.state]; 837 ZSTD_seqSymbol const mlDInfo = seqState->stateML.table[seqState->stateML.state]; 838 ZSTD_seqSymbol const ofDInfo = seqState->stateOffb.table[seqState->stateOffb.state]; 839 U32 const llBase = llDInfo.baseValue; 840 U32 const mlBase = mlDInfo.baseValue; 841 U32 const ofBase = ofDInfo.baseValue; 842 BYTE const llBits = llDInfo.nbAdditionalBits; 843 BYTE const mlBits = mlDInfo.nbAdditionalBits; 844 BYTE const ofBits = ofDInfo.nbAdditionalBits; 845 BYTE const totalBits = llBits+mlBits+ofBits; 846 847 /* sequence */ 848 { size_t offset; 849 if (ofBits > 1) { 850 ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1); 851 ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5); 852 assert(ofBits <= MaxOff); 853 if (MEM_32bits() && longOffsets && (ofBits >= STREAM_ACCUMULATOR_MIN_32)) { 854 U32 const extraBits = ofBits - MIN(ofBits, 32 - seqState->DStream.bitsConsumed); 855 offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits); 856 BIT_reloadDStream(&seqState->DStream); 857 if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits); 858 assert(extraBits <= LONG_OFFSETS_MAX_EXTRA_BITS_32); /* to avoid another reload */ 859 } else { 860 offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits/*>0*/); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */ 861 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); 862 } 863 seqState->prevOffset[2] = seqState->prevOffset[1]; 864 seqState->prevOffset[1] = seqState->prevOffset[0]; 865 seqState->prevOffset[0] = offset; 866 } else { 867 U32 const ll0 = (llBase == 0); 868 if (LIKELY((ofBits == 0))) { 869 if (LIKELY(!ll0)) 870 offset = seqState->prevOffset[0]; 871 else { 872 offset = seqState->prevOffset[1]; 873 seqState->prevOffset[1] = seqState->prevOffset[0]; 874 seqState->prevOffset[0] = offset; 875 } 876 } else { 877 offset = ofBase + ll0 + BIT_readBitsFast(&seqState->DStream, 1); 878 { size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset]; 879 temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */ 880 if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1]; 881 seqState->prevOffset[1] = seqState->prevOffset[0]; 882 seqState->prevOffset[0] = offset = temp; 883 } } } 884 seq.offset = offset; 885 } 886 887 seq.matchLength = mlBase; 888 if (mlBits > 0) 889 seq.matchLength += BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/); 890 891 if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32)) 892 BIT_reloadDStream(&seqState->DStream); 893 if (MEM_64bits() && UNLIKELY(totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog))) 894 BIT_reloadDStream(&seqState->DStream); 895 /* Ensure there are enough bits to read the rest of data in 64-bit mode. */ 896 ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64); 897 898 seq.litLength = llBase; 899 if (llBits > 0) 900 seq.litLength += BIT_readBitsFast(&seqState->DStream, llBits/*>0*/); 901 902 if (MEM_32bits()) 903 BIT_reloadDStream(&seqState->DStream); 904 905 DEBUGLOG(6, "seq: litL=%u, matchL=%u, offset=%u", 906 (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset); 907 908 /* ANS state update 909 * gcc-9.0.0 does 2.5% worse with ZSTD_updateFseStateWithDInfo(). 910 * clang-9.2.0 does 7% worse with ZSTD_updateFseState(). 911 * Naturally it seems like ZSTD_updateFseStateWithDInfo() should be the 912 * better option, so it is the default for other compilers. But, if you 913 * measure that it is worse, please put up a pull request. 914 */ 915 { 916#if defined(__GNUC__) && !defined(__clang__) 917 const int kUseUpdateFseState = 1; 918#else 919 const int kUseUpdateFseState = 0; 920#endif 921 if (kUseUpdateFseState) { 922 ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream); /* <= 9 bits */ 923 ZSTD_updateFseState(&seqState->stateML, &seqState->DStream); /* <= 9 bits */ 924 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ 925 ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream); /* <= 8 bits */ 926 } else { 927 ZSTD_updateFseStateWithDInfo(&seqState->stateLL, &seqState->DStream, llDInfo); /* <= 9 bits */ 928 ZSTD_updateFseStateWithDInfo(&seqState->stateML, &seqState->DStream, mlDInfo); /* <= 9 bits */ 929 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ 930 ZSTD_updateFseStateWithDInfo(&seqState->stateOffb, &seqState->DStream, ofDInfo); /* <= 8 bits */ 931 } 932 } 933 934 return seq; 935} 936 937#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION 938static int ZSTD_dictionaryIsActive(ZSTD_DCtx const* dctx, BYTE const* prefixStart, BYTE const* oLitEnd) 939{ 940 size_t const windowSize = dctx->fParams.windowSize; 941 /* No dictionary used. */ 942 if (dctx->dictContentEndForFuzzing == NULL) return 0; 943 /* Dictionary is our prefix. */ 944 if (prefixStart == dctx->dictContentBeginForFuzzing) return 1; 945 /* Dictionary is not our ext-dict. */ 946 if (dctx->dictEnd != dctx->dictContentEndForFuzzing) return 0; 947 /* Dictionary is not within our window size. */ 948 if ((size_t)(oLitEnd - prefixStart) >= windowSize) return 0; 949 /* Dictionary is active. */ 950 return 1; 951} 952 953MEM_STATIC void ZSTD_assertValidSequence( 954 ZSTD_DCtx const* dctx, 955 BYTE const* op, BYTE const* oend, 956 seq_t const seq, 957 BYTE const* prefixStart, BYTE const* virtualStart) 958{ 959 size_t const windowSize = dctx->fParams.windowSize; 960 size_t const sequenceSize = seq.litLength + seq.matchLength; 961 BYTE const* const oLitEnd = op + seq.litLength; 962 DEBUGLOG(6, "Checking sequence: litL=%u matchL=%u offset=%u", 963 (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset); 964 assert(op <= oend); 965 assert((size_t)(oend - op) >= sequenceSize); 966 assert(sequenceSize <= ZSTD_BLOCKSIZE_MAX); 967 if (ZSTD_dictionaryIsActive(dctx, prefixStart, oLitEnd)) { 968 size_t const dictSize = (size_t)((char const*)dctx->dictContentEndForFuzzing - (char const*)dctx->dictContentBeginForFuzzing); 969 /* Offset must be within the dictionary. */ 970 assert(seq.offset <= (size_t)(oLitEnd - virtualStart)); 971 assert(seq.offset <= windowSize + dictSize); 972 } else { 973 /* Offset must be within our window. */ 974 assert(seq.offset <= windowSize); 975 } 976} 977#endif 978 979#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG 980FORCE_INLINE_TEMPLATE size_t 981DONT_VECTORIZE 982ZSTD_decompressSequences_body( ZSTD_DCtx* dctx, 983 void* dst, size_t maxDstSize, 984 const void* seqStart, size_t seqSize, int nbSeq, 985 const ZSTD_longOffset_e isLongOffset, 986 const int frame) 987{ 988 const BYTE* ip = (const BYTE*)seqStart; 989 const BYTE* const iend = ip + seqSize; 990 BYTE* const ostart = (BYTE* const)dst; 991 BYTE* const oend = ostart + maxDstSize; 992 BYTE* op = ostart; 993 const BYTE* litPtr = dctx->litPtr; 994 const BYTE* const litEnd = litPtr + dctx->litSize; 995 const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart); 996 const BYTE* const vBase = (const BYTE*) (dctx->virtualStart); 997 const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd); 998 DEBUGLOG(5, "ZSTD_decompressSequences_body"); 999 (void)frame; 1000 1001 /* Regen sequences */ 1002 if (nbSeq) { 1003 seqState_t seqState; 1004 size_t error = 0; 1005 dctx->fseEntropy = 1; 1006 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; } 1007 RETURN_ERROR_IF( 1008 ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)), 1009 corruption_detected, ""); 1010 ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr); 1011 ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr); 1012 ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr); 1013 assert(dst != NULL); 1014 1015 ZSTD_STATIC_ASSERT( 1016 BIT_DStream_unfinished < BIT_DStream_completed && 1017 BIT_DStream_endOfBuffer < BIT_DStream_completed && 1018 BIT_DStream_completed < BIT_DStream_overflow); 1019 1020#if defined(__GNUC__) && defined(__x86_64__) 1021 /* Align the decompression loop to 32 + 16 bytes. 1022 * 1023 * zstd compiled with gcc-9 on an Intel i9-9900k shows 10% decompression 1024 * speed swings based on the alignment of the decompression loop. This 1025 * performance swing is caused by parts of the decompression loop falling 1026 * out of the DSB. The entire decompression loop should fit in the DSB, 1027 * when it can't we get much worse performance. You can measure if you've 1028 * hit the good case or the bad case with this perf command for some 1029 * compressed file test.zst: 1030 * 1031 * perf stat -e cycles -e instructions -e idq.all_dsb_cycles_any_uops \ 1032 * -e idq.all_mite_cycles_any_uops -- ./zstd -tq test.zst 1033 * 1034 * If you see most cycles served out of the MITE you've hit the bad case. 1035 * If you see most cycles served out of the DSB you've hit the good case. 1036 * If it is pretty even then you may be in an okay case. 1037 * 1038 * I've been able to reproduce this issue on the following CPUs: 1039 * - Kabylake: Macbook Pro (15-inch, 2019) 2.4 GHz Intel Core i9 1040 * Use Instruments->Counters to get DSB/MITE cycles. 1041 * I never got performance swings, but I was able to 1042 * go from the good case of mostly DSB to half of the 1043 * cycles served from MITE. 1044 * - Coffeelake: Intel i9-9900k 1045 * 1046 * I haven't been able to reproduce the instability or DSB misses on any 1047 * of the following CPUS: 1048 * - Haswell 1049 * - Broadwell: Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GH 1050 * - Skylake 1051 * 1052 * If you are seeing performance stability this script can help test. 1053 * It tests on 4 commits in zstd where I saw performance change. 1054 * 1055 * https://gist.github.com/terrelln/9889fc06a423fd5ca6e99351564473f4 1056 */ 1057 __asm__(".p2align 5"); 1058 __asm__("nop"); 1059 __asm__(".p2align 4"); 1060#endif 1061 for ( ; ; ) { 1062 seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset); 1063 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd); 1064#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) 1065 assert(!ZSTD_isError(oneSeqSize)); 1066 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase); 1067#endif 1068 DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize); 1069 BIT_reloadDStream(&(seqState.DStream)); 1070 /* gcc and clang both don't like early returns in this loop. 1071 * gcc doesn't like early breaks either. 1072 * Instead save an error and report it at the end. 1073 * When there is an error, don't increment op, so we don't 1074 * overwrite. 1075 */ 1076 if (UNLIKELY(ZSTD_isError(oneSeqSize))) error = oneSeqSize; 1077 else op += oneSeqSize; 1078 if (UNLIKELY(!--nbSeq)) break; 1079 } 1080 1081 /* check if reached exact end */ 1082 DEBUGLOG(5, "ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i", nbSeq); 1083 if (ZSTD_isError(error)) return error; 1084 RETURN_ERROR_IF(nbSeq, corruption_detected, ""); 1085 RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, corruption_detected, ""); 1086 /* save reps for next block */ 1087 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); } 1088 } 1089 1090 /* last literal segment */ 1091 { size_t const lastLLSize = litEnd - litPtr; 1092 RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, ""); 1093 if (op != NULL) { 1094 memcpy(op, litPtr, lastLLSize); 1095 op += lastLLSize; 1096 } 1097 } 1098 1099 return op-ostart; 1100} 1101 1102static size_t 1103ZSTD_decompressSequences_default(ZSTD_DCtx* dctx, 1104 void* dst, size_t maxDstSize, 1105 const void* seqStart, size_t seqSize, int nbSeq, 1106 const ZSTD_longOffset_e isLongOffset, 1107 const int frame) 1108{ 1109 return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1110} 1111#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ 1112 1113#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT 1114 1115FORCE_INLINE_TEMPLATE size_t 1116ZSTD_prefetchMatch(size_t prefixPos, seq_t const sequence, 1117 const BYTE* const prefixStart, const BYTE* const dictEnd) 1118{ 1119 prefixPos += sequence.litLength; 1120 { const BYTE* const matchBase = (sequence.offset > prefixPos) ? dictEnd : prefixStart; 1121 const BYTE* const match = matchBase + prefixPos - sequence.offset; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted. 1122 * No consequence though : no memory access will occur, offset is only used for prefetching */ 1123 PREFETCH_L1(match); PREFETCH_L1(match + sequence.matchLength - 1); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */ 1124 } 1125 return prefixPos + sequence.matchLength; 1126} 1127 1128/* This decoding function employs prefetching 1129 * to reduce latency impact of cache misses. 1130 * It's generally employed when block contains a significant portion of long-distance matches 1131 * or when coupled with a "cold" dictionary */ 1132FORCE_INLINE_TEMPLATE size_t 1133ZSTD_decompressSequencesLong_body( 1134 ZSTD_DCtx* dctx, 1135 void* dst, size_t maxDstSize, 1136 const void* seqStart, size_t seqSize, int nbSeq, 1137 const ZSTD_longOffset_e isLongOffset, 1138 const int frame) 1139{ 1140 const BYTE* ip = (const BYTE*)seqStart; 1141 const BYTE* const iend = ip + seqSize; 1142 BYTE* const ostart = (BYTE* const)dst; 1143 BYTE* const oend = ostart + maxDstSize; 1144 BYTE* op = ostart; 1145 const BYTE* litPtr = dctx->litPtr; 1146 const BYTE* const litEnd = litPtr + dctx->litSize; 1147 const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart); 1148 const BYTE* const dictStart = (const BYTE*) (dctx->virtualStart); 1149 const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd); 1150 (void)frame; 1151 1152 /* Regen sequences */ 1153 if (nbSeq) { 1154#define STORED_SEQS 4 1155#define STORED_SEQS_MASK (STORED_SEQS-1) 1156#define ADVANCED_SEQS 4 1157 seq_t sequences[STORED_SEQS]; 1158 int const seqAdvance = MIN(nbSeq, ADVANCED_SEQS); 1159 seqState_t seqState; 1160 int seqNb; 1161 size_t prefixPos = (size_t)(op-prefixStart); /* track position relative to prefixStart */ 1162 1163 dctx->fseEntropy = 1; 1164 { int i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; } 1165 assert(dst != NULL); 1166 assert(iend >= ip); 1167 RETURN_ERROR_IF( 1168 ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)), 1169 corruption_detected, ""); 1170 ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr); 1171 ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr); 1172 ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr); 1173 1174 /* prepare in advance */ 1175 for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && (seqNb<seqAdvance); seqNb++) { 1176 seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset); 1177 prefixPos = ZSTD_prefetchMatch(prefixPos, sequence, prefixStart, dictEnd); 1178 sequences[seqNb] = sequence; 1179 } 1180 RETURN_ERROR_IF(seqNb<seqAdvance, corruption_detected, ""); 1181 1182 /* decode and decompress */ 1183 for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb<nbSeq) ; seqNb++) { 1184 seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset); 1185 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd); 1186#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) 1187 assert(!ZSTD_isError(oneSeqSize)); 1188 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart); 1189#endif 1190 if (ZSTD_isError(oneSeqSize)) return oneSeqSize; 1191 1192 prefixPos = ZSTD_prefetchMatch(prefixPos, sequence, prefixStart, dictEnd); 1193 sequences[seqNb & STORED_SEQS_MASK] = sequence; 1194 op += oneSeqSize; 1195 } 1196 RETURN_ERROR_IF(seqNb<nbSeq, corruption_detected, ""); 1197 1198 /* finish queue */ 1199 seqNb -= seqAdvance; 1200 for ( ; seqNb<nbSeq ; seqNb++) { 1201 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequences[seqNb&STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd); 1202#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) 1203 assert(!ZSTD_isError(oneSeqSize)); 1204 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart); 1205#endif 1206 if (ZSTD_isError(oneSeqSize)) return oneSeqSize; 1207 op += oneSeqSize; 1208 } 1209 1210 /* save reps for next block */ 1211 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); } 1212 } 1213 1214 /* last literal segment */ 1215 { size_t const lastLLSize = litEnd - litPtr; 1216 RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, ""); 1217 if (op != NULL) { 1218 memcpy(op, litPtr, lastLLSize); 1219 op += lastLLSize; 1220 } 1221 } 1222 1223 return op-ostart; 1224} 1225 1226static size_t 1227ZSTD_decompressSequencesLong_default(ZSTD_DCtx* dctx, 1228 void* dst, size_t maxDstSize, 1229 const void* seqStart, size_t seqSize, int nbSeq, 1230 const ZSTD_longOffset_e isLongOffset, 1231 const int frame) 1232{ 1233 return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1234} 1235#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ 1236 1237 1238 1239#if DYNAMIC_BMI2 1240 1241#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG 1242static TARGET_ATTRIBUTE("bmi2") size_t 1243DONT_VECTORIZE 1244ZSTD_decompressSequences_bmi2(ZSTD_DCtx* dctx, 1245 void* dst, size_t maxDstSize, 1246 const void* seqStart, size_t seqSize, int nbSeq, 1247 const ZSTD_longOffset_e isLongOffset, 1248 const int frame) 1249{ 1250 return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1251} 1252#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ 1253 1254#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT 1255static TARGET_ATTRIBUTE("bmi2") size_t 1256ZSTD_decompressSequencesLong_bmi2(ZSTD_DCtx* dctx, 1257 void* dst, size_t maxDstSize, 1258 const void* seqStart, size_t seqSize, int nbSeq, 1259 const ZSTD_longOffset_e isLongOffset, 1260 const int frame) 1261{ 1262 return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1263} 1264#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ 1265 1266#endif /* DYNAMIC_BMI2 */ 1267 1268typedef size_t (*ZSTD_decompressSequences_t)( 1269 ZSTD_DCtx* dctx, 1270 void* dst, size_t maxDstSize, 1271 const void* seqStart, size_t seqSize, int nbSeq, 1272 const ZSTD_longOffset_e isLongOffset, 1273 const int frame); 1274 1275#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG 1276static size_t 1277ZSTD_decompressSequences(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, 1278 const void* seqStart, size_t seqSize, int nbSeq, 1279 const ZSTD_longOffset_e isLongOffset, 1280 const int frame) 1281{ 1282 DEBUGLOG(5, "ZSTD_decompressSequences"); 1283#if DYNAMIC_BMI2 1284 if (dctx->bmi2) { 1285 return ZSTD_decompressSequences_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1286 } 1287#endif 1288 return ZSTD_decompressSequences_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1289} 1290#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ 1291 1292 1293#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT 1294/* ZSTD_decompressSequencesLong() : 1295 * decompression function triggered when a minimum share of offsets is considered "long", 1296 * aka out of cache. 1297 * note : "long" definition seems overloaded here, sometimes meaning "wider than bitstream register", and sometimes meaning "farther than memory cache distance". 1298 * This function will try to mitigate main memory latency through the use of prefetching */ 1299static size_t 1300ZSTD_decompressSequencesLong(ZSTD_DCtx* dctx, 1301 void* dst, size_t maxDstSize, 1302 const void* seqStart, size_t seqSize, int nbSeq, 1303 const ZSTD_longOffset_e isLongOffset, 1304 const int frame) 1305{ 1306 DEBUGLOG(5, "ZSTD_decompressSequencesLong"); 1307#if DYNAMIC_BMI2 1308 if (dctx->bmi2) { 1309 return ZSTD_decompressSequencesLong_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1310 } 1311#endif 1312 return ZSTD_decompressSequencesLong_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1313} 1314#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ 1315 1316 1317 1318#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 1319 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 1320/* ZSTD_getLongOffsetsShare() : 1321 * condition : offTable must be valid 1322 * @return : "share" of long offsets (arbitrarily defined as > (1<<23)) 1323 * compared to maximum possible of (1<<OffFSELog) */ 1324static unsigned 1325ZSTD_getLongOffsetsShare(const ZSTD_seqSymbol* offTable) 1326{ 1327 const void* ptr = offTable; 1328 U32 const tableLog = ((const ZSTD_seqSymbol_header*)ptr)[0].tableLog; 1329 const ZSTD_seqSymbol* table = offTable + 1; 1330 U32 const max = 1 << tableLog; 1331 U32 u, total = 0; 1332 DEBUGLOG(5, "ZSTD_getLongOffsetsShare: (tableLog=%u)", tableLog); 1333 1334 assert(max <= (1 << OffFSELog)); /* max not too large */ 1335 for (u=0; u<max; u++) { 1336 if (table[u].nbAdditionalBits > 22) total += 1; 1337 } 1338 1339 assert(tableLog <= OffFSELog); 1340 total <<= (OffFSELog - tableLog); /* scale to OffFSELog */ 1341 1342 return total; 1343} 1344#endif 1345 1346size_t 1347ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx, 1348 void* dst, size_t dstCapacity, 1349 const void* src, size_t srcSize, const int frame) 1350{ /* blockType == blockCompressed */ 1351 const BYTE* ip = (const BYTE*)src; 1352 /* isLongOffset must be true if there are long offsets. 1353 * Offsets are long if they are larger than 2^STREAM_ACCUMULATOR_MIN. 1354 * We don't expect that to be the case in 64-bit mode. 1355 * In block mode, window size is not known, so we have to be conservative. 1356 * (note: but it could be evaluated from current-lowLimit) 1357 */ 1358 ZSTD_longOffset_e const isLongOffset = (ZSTD_longOffset_e)(MEM_32bits() && (!frame || (dctx->fParams.windowSize > (1ULL << STREAM_ACCUMULATOR_MIN)))); 1359 DEBUGLOG(5, "ZSTD_decompressBlock_internal (size : %u)", (U32)srcSize); 1360 1361 RETURN_ERROR_IF(srcSize >= ZSTD_BLOCKSIZE_MAX, srcSize_wrong, ""); 1362 1363 /* Decode literals section */ 1364 { size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize); 1365 DEBUGLOG(5, "ZSTD_decodeLiteralsBlock : %u", (U32)litCSize); 1366 if (ZSTD_isError(litCSize)) return litCSize; 1367 ip += litCSize; 1368 srcSize -= litCSize; 1369 } 1370 1371 /* Build Decoding Tables */ 1372 { 1373 /* These macros control at build-time which decompressor implementation 1374 * we use. If neither is defined, we do some inspection and dispatch at 1375 * runtime. 1376 */ 1377#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 1378 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 1379 int usePrefetchDecoder = dctx->ddictIsCold; 1380#endif 1381 int nbSeq; 1382 size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize); 1383 if (ZSTD_isError(seqHSize)) return seqHSize; 1384 ip += seqHSize; 1385 srcSize -= seqHSize; 1386 1387 RETURN_ERROR_IF(dst == NULL && nbSeq > 0, dstSize_tooSmall, "NULL not handled"); 1388 1389#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 1390 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 1391 if ( !usePrefetchDecoder 1392 && (!frame || (dctx->fParams.windowSize > (1<<24))) 1393 && (nbSeq>ADVANCED_SEQS) ) { /* could probably use a larger nbSeq limit */ 1394 U32 const shareLongOffsets = ZSTD_getLongOffsetsShare(dctx->OFTptr); 1395 U32 const minShare = MEM_64bits() ? 7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */ 1396 usePrefetchDecoder = (shareLongOffsets >= minShare); 1397 } 1398#endif 1399 1400 dctx->ddictIsCold = 0; 1401 1402#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 1403 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 1404 if (usePrefetchDecoder) 1405#endif 1406#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT 1407 return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame); 1408#endif 1409 1410#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG 1411 /* else */ 1412 return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame); 1413#endif 1414 } 1415} 1416 1417 1418void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst) 1419{ 1420 if (dst != dctx->previousDstEnd) { /* not contiguous */ 1421 dctx->dictEnd = dctx->previousDstEnd; 1422 dctx->virtualStart = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->prefixStart)); 1423 dctx->prefixStart = dst; 1424 dctx->previousDstEnd = dst; 1425 } 1426} 1427 1428 1429size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, 1430 void* dst, size_t dstCapacity, 1431 const void* src, size_t srcSize) 1432{ 1433 size_t dSize; 1434 ZSTD_checkContinuity(dctx, dst); 1435 dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize, /* frame */ 0); 1436 dctx->previousDstEnd = (char*)dst + dSize; 1437 return dSize; 1438} 1439