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 "compiler.h" /* prefetch */
19 #include "cpu.h" /* bmi2 */
20 #include "mem.h" /* low level memory routines */
21 #define FSE_STATIC_LINKING_ONLY
22 #include "fse.h"
23 #define HUF_STATIC_LINKING_ONLY
24 #include "huf.h"
25 #include "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 **********************************************************/
ZSTD_copy4(void * dst,const void * src)47 static 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` */
ZSTD_getcBlockSize(const void * src,size_t srcSize,blockProperties_t * bpPtr)56 size_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 */
74 size_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 */
ZSTD_decodeLiteralsBlock(ZSTD_DCtx * dctx,const void * src,size_t srcSize)79 size_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 */
247 static 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 */
285 static 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 */
308 static 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
ZSTD_buildSeqTable_rle(ZSTD_seqSymbol * dt,U32 baseValue,U32 nbAddBits)346 static 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 */
367 void
ZSTD_buildFSETable(ZSTD_seqSymbol * dt,const short * normalizedCounter,unsigned maxSymbolValue,const U32 * baseValue,const U32 * nbAdditionalBits,unsigned tableLog)368 ZSTD_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 */
ZSTD_buildSeqTable(ZSTD_seqSymbol * DTableSpace,const ZSTD_seqSymbol ** DTablePtr,symbolEncodingType_e type,unsigned max,U32 maxLog,const void * src,size_t srcSize,const U32 * baseValue,const U32 * nbAdditionalBits,const ZSTD_seqSymbol * defaultTable,U32 flagRepeatTable,int ddictIsCold,int nbSeq)433 static 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
ZSTD_decodeSeqHeaders(ZSTD_DCtx * dctx,int * nbSeqPtr,const void * src,size_t srcSize)480 size_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
553 typedef struct {
554 size_t litLength;
555 size_t matchLength;
556 size_t offset;
557 const BYTE* match;
558 } seq_t;
559
560 typedef struct {
561 size_t state;
562 const ZSTD_seqSymbol* table;
563 } ZSTD_fseState;
564
565 typedef struct {
566 BIT_DStream_t DStream;
567 ZSTD_fseState stateLL;
568 ZSTD_fseState stateOffb;
569 ZSTD_fseState stateML;
570 size_t prevOffset[ZSTD_REP_NUM];
571 const BYTE* prefixStart;
572 const BYTE* dictEnd;
573 size_t pos;
574 } seqState_t;
575
576 /*! ZSTD_overlapCopy8() :
577 * Copies 8 bytes from ip to op and updates op and ip where ip <= op.
578 * If the offset is < 8 then the offset is spread to at least 8 bytes.
579 *
580 * Precondition: *ip <= *op
581 * Postcondition: *op - *op >= 8
582 */
ZSTD_overlapCopy8(BYTE ** op,BYTE const ** ip,size_t offset)583 HINT_INLINE void ZSTD_overlapCopy8(BYTE** op, BYTE const** ip, size_t offset) {
584 assert(*ip <= *op);
585 if (offset < 8) {
586 /* close range match, overlap */
587 static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */
588 static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */
589 int const sub2 = dec64table[offset];
590 (*op)[0] = (*ip)[0];
591 (*op)[1] = (*ip)[1];
592 (*op)[2] = (*ip)[2];
593 (*op)[3] = (*ip)[3];
594 *ip += dec32table[offset];
595 ZSTD_copy4(*op+4, *ip);
596 *ip -= sub2;
597 } else {
598 ZSTD_copy8(*op, *ip);
599 }
600 *ip += 8;
601 *op += 8;
602 assert(*op - *ip >= 8);
603 }
604
605 /*! ZSTD_safecopy() :
606 * Specialized version of memcpy() that is allowed to READ up to WILDCOPY_OVERLENGTH past the input buffer
607 * and write up to 16 bytes past oend_w (op >= oend_w is allowed).
608 * This function is only called in the uncommon case where the sequence is near the end of the block. It
609 * should be fast for a single long sequence, but can be slow for several short sequences.
610 *
611 * @param ovtype controls the overlap detection
612 * - ZSTD_no_overlap: The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart.
613 * - ZSTD_overlap_src_before_dst: The src and dst may overlap and may be any distance apart.
614 * The src buffer must be before the dst buffer.
615 */
ZSTD_safecopy(BYTE * op,BYTE * const oend_w,BYTE const * ip,ptrdiff_t length,ZSTD_overlap_e ovtype)616 static void ZSTD_safecopy(BYTE* op, BYTE* const oend_w, BYTE const* ip, ptrdiff_t length, ZSTD_overlap_e ovtype) {
617 ptrdiff_t const diff = op - ip;
618 BYTE* const oend = op + length;
619
620 assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8 || op >= oend_w)) ||
621 (ovtype == ZSTD_overlap_src_before_dst && diff >= 0));
622
623 if (length < 8) {
624 /* Handle short lengths. */
625 while (op < oend) *op++ = *ip++;
626 return;
627 }
628 if (ovtype == ZSTD_overlap_src_before_dst) {
629 /* Copy 8 bytes and ensure the offset >= 8 when there can be overlap. */
630 assert(length >= 8);
631 ZSTD_overlapCopy8(&op, &ip, diff);
632 assert(op - ip >= 8);
633 assert(op <= oend);
634 }
635
636 if (oend <= oend_w) {
637 /* No risk of overwrite. */
638 ZSTD_wildcopy(op, ip, length, ovtype);
639 return;
640 }
641 if (op <= oend_w) {
642 /* Wildcopy until we get close to the end. */
643 assert(oend > oend_w);
644 ZSTD_wildcopy(op, ip, oend_w - op, ovtype);
645 ip += oend_w - op;
646 op = oend_w;
647 }
648 /* Handle the leftovers. */
649 while (op < oend) *op++ = *ip++;
650 }
651
652 /* ZSTD_execSequenceEnd():
653 * This version handles cases that are near the end of the output buffer. It requires
654 * more careful checks to make sure there is no overflow. By separating out these hard
655 * and unlikely cases, we can speed up the common cases.
656 *
657 * NOTE: This function needs to be fast for a single long sequence, but doesn't need
658 * to be optimized for many small sequences, since those fall into ZSTD_execSequence().
659 */
660 FORCE_NOINLINE
ZSTD_execSequenceEnd(BYTE * op,BYTE * const oend,seq_t sequence,const BYTE ** litPtr,const BYTE * const litLimit,const BYTE * const prefixStart,const BYTE * const virtualStart,const BYTE * const dictEnd)661 size_t ZSTD_execSequenceEnd(BYTE* op,
662 BYTE* const oend, seq_t sequence,
663 const BYTE** litPtr, const BYTE* const litLimit,
664 const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
665 {
666 BYTE* const oLitEnd = op + sequence.litLength;
667 size_t const sequenceLength = sequence.litLength + sequence.matchLength;
668 const BYTE* const iLitEnd = *litPtr + sequence.litLength;
669 const BYTE* match = oLitEnd - sequence.offset;
670 BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
671
672 /* bounds checks : careful of address space overflow in 32-bit mode */
673 RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer");
674 RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer");
675 assert(op < op + sequenceLength);
676 assert(oLitEnd < op + sequenceLength);
677
678 /* copy literals */
679 ZSTD_safecopy(op, oend_w, *litPtr, sequence.litLength, ZSTD_no_overlap);
680 op = oLitEnd;
681 *litPtr = iLitEnd;
682
683 /* copy Match */
684 if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
685 /* offset beyond prefix */
686 RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, "");
687 match = dictEnd - (prefixStart-match);
688 if (match + sequence.matchLength <= dictEnd) {
689 memmove(oLitEnd, match, sequence.matchLength);
690 return sequenceLength;
691 }
692 /* span extDict & currentPrefixSegment */
693 { size_t const length1 = dictEnd - match;
694 memmove(oLitEnd, match, length1);
695 op = oLitEnd + length1;
696 sequence.matchLength -= length1;
697 match = prefixStart;
698 } }
699 ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst);
700 return sequenceLength;
701 }
702
703 HINT_INLINE
ZSTD_execSequence(BYTE * op,BYTE * const oend,seq_t sequence,const BYTE ** litPtr,const BYTE * const litLimit,const BYTE * const prefixStart,const BYTE * const virtualStart,const BYTE * const dictEnd)704 size_t ZSTD_execSequence(BYTE* op,
705 BYTE* const oend, seq_t sequence,
706 const BYTE** litPtr, const BYTE* const litLimit,
707 const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
708 {
709 BYTE* const oLitEnd = op + sequence.litLength;
710 size_t const sequenceLength = sequence.litLength + sequence.matchLength;
711 BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */
712 BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; /* risk : address space underflow on oend=NULL */
713 const BYTE* const iLitEnd = *litPtr + sequence.litLength;
714 const BYTE* match = oLitEnd - sequence.offset;
715
716 assert(op != NULL /* Precondition */);
717 assert(oend_w < oend /* No underflow */);
718 /* Handle edge cases in a slow path:
719 * - Read beyond end of literals
720 * - Match end is within WILDCOPY_OVERLIMIT of oend
721 * - 32-bit mode and the match length overflows
722 */
723 if (UNLIKELY(
724 iLitEnd > litLimit ||
725 oMatchEnd > oend_w ||
726 (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH)))
727 return ZSTD_execSequenceEnd(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd);
728
729 /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */
730 assert(op <= oLitEnd /* No overflow */);
731 assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */);
732 assert(oMatchEnd <= oend /* No underflow */);
733 assert(iLitEnd <= litLimit /* Literal length is in bounds */);
734 assert(oLitEnd <= oend_w /* Can wildcopy literals */);
735 assert(oMatchEnd <= oend_w /* Can wildcopy matches */);
736
737 /* Copy Literals:
738 * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9.
739 * We likely don't need the full 32-byte wildcopy.
740 */
741 assert(WILDCOPY_OVERLENGTH >= 16);
742 ZSTD_copy16(op, (*litPtr));
743 if (UNLIKELY(sequence.litLength > 16)) {
744 ZSTD_wildcopy(op+16, (*litPtr)+16, sequence.litLength-16, ZSTD_no_overlap);
745 }
746 op = oLitEnd;
747 *litPtr = iLitEnd; /* update for next sequence */
748
749 /* Copy Match */
750 if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
751 /* offset beyond prefix -> go into extDict */
752 RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, "");
753 match = dictEnd + (match - prefixStart);
754 if (match + sequence.matchLength <= dictEnd) {
755 memmove(oLitEnd, match, sequence.matchLength);
756 return sequenceLength;
757 }
758 /* span extDict & currentPrefixSegment */
759 { size_t const length1 = dictEnd - match;
760 memmove(oLitEnd, match, length1);
761 op = oLitEnd + length1;
762 sequence.matchLength -= length1;
763 match = prefixStart;
764 } }
765 /* Match within prefix of 1 or more bytes */
766 assert(op <= oMatchEnd);
767 assert(oMatchEnd <= oend_w);
768 assert(match >= prefixStart);
769 assert(sequence.matchLength >= 1);
770
771 /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy
772 * without overlap checking.
773 */
774 if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) {
775 /* We bet on a full wildcopy for matches, since we expect matches to be
776 * longer than literals (in general). In silesia, ~10% of matches are longer
777 * than 16 bytes.
778 */
779 ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap);
780 return sequenceLength;
781 }
782 assert(sequence.offset < WILDCOPY_VECLEN);
783
784 /* Copy 8 bytes and spread the offset to be >= 8. */
785 ZSTD_overlapCopy8(&op, &match, sequence.offset);
786
787 /* If the match length is > 8 bytes, then continue with the wildcopy. */
788 if (sequence.matchLength > 8) {
789 assert(op < oMatchEnd);
790 ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst);
791 }
792 return sequenceLength;
793 }
794
795 static void
ZSTD_initFseState(ZSTD_fseState * DStatePtr,BIT_DStream_t * bitD,const ZSTD_seqSymbol * dt)796 ZSTD_initFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, const ZSTD_seqSymbol* dt)
797 {
798 const void* ptr = dt;
799 const ZSTD_seqSymbol_header* const DTableH = (const ZSTD_seqSymbol_header*)ptr;
800 DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog);
801 DEBUGLOG(6, "ZSTD_initFseState : val=%u using %u bits",
802 (U32)DStatePtr->state, DTableH->tableLog);
803 BIT_reloadDStream(bitD);
804 DStatePtr->table = dt + 1;
805 }
806
807 FORCE_INLINE_TEMPLATE void
ZSTD_updateFseState(ZSTD_fseState * DStatePtr,BIT_DStream_t * bitD)808 ZSTD_updateFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD)
809 {
810 ZSTD_seqSymbol const DInfo = DStatePtr->table[DStatePtr->state];
811 U32 const nbBits = DInfo.nbBits;
812 size_t const lowBits = BIT_readBits(bitD, nbBits);
813 DStatePtr->state = DInfo.nextState + lowBits;
814 }
815
816 FORCE_INLINE_TEMPLATE void
ZSTD_updateFseStateWithDInfo(ZSTD_fseState * DStatePtr,BIT_DStream_t * bitD,ZSTD_seqSymbol const DInfo)817 ZSTD_updateFseStateWithDInfo(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, ZSTD_seqSymbol const DInfo)
818 {
819 U32 const nbBits = DInfo.nbBits;
820 size_t const lowBits = BIT_readBits(bitD, nbBits);
821 DStatePtr->state = DInfo.nextState + lowBits;
822 }
823
824 /* We need to add at most (ZSTD_WINDOWLOG_MAX_32 - 1) bits to read the maximum
825 * offset bits. But we can only read at most (STREAM_ACCUMULATOR_MIN_32 - 1)
826 * bits before reloading. This value is the maximum number of bytes we read
827 * after reloading when we are decoding long offsets.
828 */
829 #define LONG_OFFSETS_MAX_EXTRA_BITS_32 \
830 (ZSTD_WINDOWLOG_MAX_32 > STREAM_ACCUMULATOR_MIN_32 \
831 ? ZSTD_WINDOWLOG_MAX_32 - STREAM_ACCUMULATOR_MIN_32 \
832 : 0)
833
834 typedef enum { ZSTD_lo_isRegularOffset, ZSTD_lo_isLongOffset=1 } ZSTD_longOffset_e;
835 typedef enum { ZSTD_p_noPrefetch=0, ZSTD_p_prefetch=1 } ZSTD_prefetch_e;
836
837 FORCE_INLINE_TEMPLATE seq_t
ZSTD_decodeSequence(seqState_t * seqState,const ZSTD_longOffset_e longOffsets,const ZSTD_prefetch_e prefetch)838 ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets, const ZSTD_prefetch_e prefetch)
839 {
840 seq_t seq;
841 ZSTD_seqSymbol const llDInfo = seqState->stateLL.table[seqState->stateLL.state];
842 ZSTD_seqSymbol const mlDInfo = seqState->stateML.table[seqState->stateML.state];
843 ZSTD_seqSymbol const ofDInfo = seqState->stateOffb.table[seqState->stateOffb.state];
844 U32 const llBase = llDInfo.baseValue;
845 U32 const mlBase = mlDInfo.baseValue;
846 U32 const ofBase = ofDInfo.baseValue;
847 BYTE const llBits = llDInfo.nbAdditionalBits;
848 BYTE const mlBits = mlDInfo.nbAdditionalBits;
849 BYTE const ofBits = ofDInfo.nbAdditionalBits;
850 BYTE const totalBits = llBits+mlBits+ofBits;
851
852 /* sequence */
853 { size_t offset;
854 if (ofBits > 1) {
855 ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1);
856 ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5);
857 assert(ofBits <= MaxOff);
858 if (MEM_32bits() && longOffsets && (ofBits >= STREAM_ACCUMULATOR_MIN_32)) {
859 U32 const extraBits = ofBits - MIN(ofBits, 32 - seqState->DStream.bitsConsumed);
860 offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits);
861 BIT_reloadDStream(&seqState->DStream);
862 if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits);
863 assert(extraBits <= LONG_OFFSETS_MAX_EXTRA_BITS_32); /* to avoid another reload */
864 } else {
865 offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits/*>0*/); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */
866 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
867 }
868 seqState->prevOffset[2] = seqState->prevOffset[1];
869 seqState->prevOffset[1] = seqState->prevOffset[0];
870 seqState->prevOffset[0] = offset;
871 } else {
872 U32 const ll0 = (llBase == 0);
873 if (LIKELY((ofBits == 0))) {
874 if (LIKELY(!ll0))
875 offset = seqState->prevOffset[0];
876 else {
877 offset = seqState->prevOffset[1];
878 seqState->prevOffset[1] = seqState->prevOffset[0];
879 seqState->prevOffset[0] = offset;
880 }
881 } else {
882 offset = ofBase + ll0 + BIT_readBitsFast(&seqState->DStream, 1);
883 { size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
884 temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */
885 if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
886 seqState->prevOffset[1] = seqState->prevOffset[0];
887 seqState->prevOffset[0] = offset = temp;
888 } } }
889 seq.offset = offset;
890 }
891
892 seq.matchLength = mlBase;
893 if (mlBits > 0)
894 seq.matchLength += BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/);
895
896 if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32))
897 BIT_reloadDStream(&seqState->DStream);
898 if (MEM_64bits() && UNLIKELY(totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog)))
899 BIT_reloadDStream(&seqState->DStream);
900 /* Ensure there are enough bits to read the rest of data in 64-bit mode. */
901 ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64);
902
903 seq.litLength = llBase;
904 if (llBits > 0)
905 seq.litLength += BIT_readBitsFast(&seqState->DStream, llBits/*>0*/);
906
907 if (MEM_32bits())
908 BIT_reloadDStream(&seqState->DStream);
909
910 DEBUGLOG(6, "seq: litL=%u, matchL=%u, offset=%u",
911 (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset);
912
913 if (prefetch == ZSTD_p_prefetch) {
914 size_t const pos = seqState->pos + seq.litLength;
915 const BYTE* const matchBase = (seq.offset > pos) ? seqState->dictEnd : seqState->prefixStart;
916 seq.match = matchBase + pos - seq.offset; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted.
917 * No consequence though : no memory access will occur, offset is only used for prefetching */
918 seqState->pos = pos + seq.matchLength;
919 }
920
921 /* ANS state update
922 * gcc-9.0.0 does 2.5% worse with ZSTD_updateFseStateWithDInfo().
923 * clang-9.2.0 does 7% worse with ZSTD_updateFseState().
924 * Naturally it seems like ZSTD_updateFseStateWithDInfo() should be the
925 * better option, so it is the default for other compilers. But, if you
926 * measure that it is worse, please put up a pull request.
927 */
928 {
929 #if defined(__GNUC__) && !defined(__clang__)
930 const int kUseUpdateFseState = 1;
931 #else
932 const int kUseUpdateFseState = 0;
933 #endif
934 if (kUseUpdateFseState) {
935 ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream); /* <= 9 bits */
936 ZSTD_updateFseState(&seqState->stateML, &seqState->DStream); /* <= 9 bits */
937 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */
938 ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream); /* <= 8 bits */
939 } else {
940 ZSTD_updateFseStateWithDInfo(&seqState->stateLL, &seqState->DStream, llDInfo); /* <= 9 bits */
941 ZSTD_updateFseStateWithDInfo(&seqState->stateML, &seqState->DStream, mlDInfo); /* <= 9 bits */
942 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */
943 ZSTD_updateFseStateWithDInfo(&seqState->stateOffb, &seqState->DStream, ofDInfo); /* <= 8 bits */
944 }
945 }
946
947 return seq;
948 }
949
950 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
ZSTD_dictionaryIsActive(ZSTD_DCtx const * dctx,BYTE const * prefixStart,BYTE const * oLitEnd)951 static int ZSTD_dictionaryIsActive(ZSTD_DCtx const* dctx, BYTE const* prefixStart, BYTE const* oLitEnd)
952 {
953 size_t const windowSize = dctx->fParams.windowSize;
954 /* No dictionary used. */
955 if (dctx->dictContentEndForFuzzing == NULL) return 0;
956 /* Dictionary is our prefix. */
957 if (prefixStart == dctx->dictContentBeginForFuzzing) return 1;
958 /* Dictionary is not our ext-dict. */
959 if (dctx->dictEnd != dctx->dictContentEndForFuzzing) return 0;
960 /* Dictionary is not within our window size. */
961 if ((size_t)(oLitEnd - prefixStart) >= windowSize) return 0;
962 /* Dictionary is active. */
963 return 1;
964 }
965
ZSTD_assertValidSequence(ZSTD_DCtx const * dctx,BYTE const * op,BYTE const * oend,seq_t const seq,BYTE const * prefixStart,BYTE const * virtualStart)966 MEM_STATIC void ZSTD_assertValidSequence(
967 ZSTD_DCtx const* dctx,
968 BYTE const* op, BYTE const* oend,
969 seq_t const seq,
970 BYTE const* prefixStart, BYTE const* virtualStart)
971 {
972 size_t const windowSize = dctx->fParams.windowSize;
973 size_t const sequenceSize = seq.litLength + seq.matchLength;
974 BYTE const* const oLitEnd = op + seq.litLength;
975 DEBUGLOG(6, "Checking sequence: litL=%u matchL=%u offset=%u",
976 (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset);
977 assert(op <= oend);
978 assert((size_t)(oend - op) >= sequenceSize);
979 assert(sequenceSize <= ZSTD_BLOCKSIZE_MAX);
980 if (ZSTD_dictionaryIsActive(dctx, prefixStart, oLitEnd)) {
981 size_t const dictSize = (size_t)((char const*)dctx->dictContentEndForFuzzing - (char const*)dctx->dictContentBeginForFuzzing);
982 /* Offset must be within the dictionary. */
983 assert(seq.offset <= (size_t)(oLitEnd - virtualStart));
984 assert(seq.offset <= windowSize + dictSize);
985 } else {
986 /* Offset must be within our window. */
987 assert(seq.offset <= windowSize);
988 }
989 }
990 #endif
991
992 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
993 FORCE_INLINE_TEMPLATE size_t
994 DONT_VECTORIZE
ZSTD_decompressSequences_body(ZSTD_DCtx * dctx,void * dst,size_t maxDstSize,const void * seqStart,size_t seqSize,int nbSeq,const ZSTD_longOffset_e isLongOffset,const int frame)995 ZSTD_decompressSequences_body( ZSTD_DCtx* dctx,
996 void* dst, size_t maxDstSize,
997 const void* seqStart, size_t seqSize, int nbSeq,
998 const ZSTD_longOffset_e isLongOffset,
999 const int frame)
1000 {
1001 const BYTE* ip = (const BYTE*)seqStart;
1002 const BYTE* const iend = ip + seqSize;
1003 BYTE* const ostart = (BYTE* const)dst;
1004 BYTE* const oend = ostart + maxDstSize;
1005 BYTE* op = ostart;
1006 const BYTE* litPtr = dctx->litPtr;
1007 const BYTE* const litEnd = litPtr + dctx->litSize;
1008 const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart);
1009 const BYTE* const vBase = (const BYTE*) (dctx->virtualStart);
1010 const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
1011 DEBUGLOG(5, "ZSTD_decompressSequences_body");
1012 (void)frame;
1013
1014 /* Regen sequences */
1015 if (nbSeq) {
1016 seqState_t seqState;
1017 size_t error = 0;
1018 dctx->fseEntropy = 1;
1019 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
1020 RETURN_ERROR_IF(
1021 ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)),
1022 corruption_detected, "");
1023 ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
1024 ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
1025 ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
1026 assert(dst != NULL);
1027
1028 ZSTD_STATIC_ASSERT(
1029 BIT_DStream_unfinished < BIT_DStream_completed &&
1030 BIT_DStream_endOfBuffer < BIT_DStream_completed &&
1031 BIT_DStream_completed < BIT_DStream_overflow);
1032
1033 #if defined(__GNUC__) && defined(__x86_64__)
1034 /* Align the decompression loop to 32 + 16 bytes.
1035 *
1036 * zstd compiled with gcc-9 on an Intel i9-9900k shows 10% decompression
1037 * speed swings based on the alignment of the decompression loop. This
1038 * performance swing is caused by parts of the decompression loop falling
1039 * out of the DSB. The entire decompression loop should fit in the DSB,
1040 * when it can't we get much worse performance. You can measure if you've
1041 * hit the good case or the bad case with this perf command for some
1042 * compressed file test.zst:
1043 *
1044 * perf stat -e cycles -e instructions -e idq.all_dsb_cycles_any_uops \
1045 * -e idq.all_mite_cycles_any_uops -- ./zstd -tq test.zst
1046 *
1047 * If you see most cycles served out of the MITE you've hit the bad case.
1048 * If you see most cycles served out of the DSB you've hit the good case.
1049 * If it is pretty even then you may be in an okay case.
1050 *
1051 * I've been able to reproduce this issue on the following CPUs:
1052 * - Kabylake: Macbook Pro (15-inch, 2019) 2.4 GHz Intel Core i9
1053 * Use Instruments->Counters to get DSB/MITE cycles.
1054 * I never got performance swings, but I was able to
1055 * go from the good case of mostly DSB to half of the
1056 * cycles served from MITE.
1057 * - Coffeelake: Intel i9-9900k
1058 *
1059 * I haven't been able to reproduce the instability or DSB misses on any
1060 * of the following CPUS:
1061 * - Haswell
1062 * - Broadwell: Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GH
1063 * - Skylake
1064 *
1065 * If you are seeing performance stability this script can help test.
1066 * It tests on 4 commits in zstd where I saw performance change.
1067 *
1068 * https://gist.github.com/terrelln/9889fc06a423fd5ca6e99351564473f4
1069 */
1070 __asm__(".p2align 5");
1071 __asm__("nop");
1072 __asm__(".p2align 4");
1073 #endif
1074 for ( ; ; ) {
1075 seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset, ZSTD_p_noPrefetch);
1076 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd);
1077 #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
1078 assert(!ZSTD_isError(oneSeqSize));
1079 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
1080 #endif
1081 DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
1082 BIT_reloadDStream(&(seqState.DStream));
1083 /* gcc and clang both don't like early returns in this loop.
1084 * gcc doesn't like early breaks either.
1085 * Instead save an error and report it at the end.
1086 * When there is an error, don't increment op, so we don't
1087 * overwrite.
1088 */
1089 if (UNLIKELY(ZSTD_isError(oneSeqSize))) error = oneSeqSize;
1090 else op += oneSeqSize;
1091 if (UNLIKELY(!--nbSeq)) break;
1092 }
1093
1094 /* check if reached exact end */
1095 DEBUGLOG(5, "ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i", nbSeq);
1096 if (ZSTD_isError(error)) return error;
1097 RETURN_ERROR_IF(nbSeq, corruption_detected, "");
1098 RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, corruption_detected, "");
1099 /* save reps for next block */
1100 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
1101 }
1102
1103 /* last literal segment */
1104 { size_t const lastLLSize = litEnd - litPtr;
1105 RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
1106 if (op != NULL) {
1107 memcpy(op, litPtr, lastLLSize);
1108 op += lastLLSize;
1109 }
1110 }
1111
1112 return op-ostart;
1113 }
1114
1115 static size_t
ZSTD_decompressSequences_default(ZSTD_DCtx * dctx,void * dst,size_t maxDstSize,const void * seqStart,size_t seqSize,int nbSeq,const ZSTD_longOffset_e isLongOffset,const int frame)1116 ZSTD_decompressSequences_default(ZSTD_DCtx* dctx,
1117 void* dst, size_t maxDstSize,
1118 const void* seqStart, size_t seqSize, int nbSeq,
1119 const ZSTD_longOffset_e isLongOffset,
1120 const int frame)
1121 {
1122 return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
1123 }
1124 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
1125
1126 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
1127 FORCE_INLINE_TEMPLATE size_t
ZSTD_decompressSequencesLong_body(ZSTD_DCtx * dctx,void * dst,size_t maxDstSize,const void * seqStart,size_t seqSize,int nbSeq,const ZSTD_longOffset_e isLongOffset,const int frame)1128 ZSTD_decompressSequencesLong_body(
1129 ZSTD_DCtx* dctx,
1130 void* dst, size_t maxDstSize,
1131 const void* seqStart, size_t seqSize, int nbSeq,
1132 const ZSTD_longOffset_e isLongOffset,
1133 const int frame)
1134 {
1135 const BYTE* ip = (const BYTE*)seqStart;
1136 const BYTE* const iend = ip + seqSize;
1137 BYTE* const ostart = (BYTE* const)dst;
1138 BYTE* const oend = ostart + maxDstSize;
1139 BYTE* op = ostart;
1140 const BYTE* litPtr = dctx->litPtr;
1141 const BYTE* const litEnd = litPtr + dctx->litSize;
1142 const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart);
1143 const BYTE* const dictStart = (const BYTE*) (dctx->virtualStart);
1144 const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
1145 (void)frame;
1146
1147 /* Regen sequences */
1148 if (nbSeq) {
1149 #define STORED_SEQS 4
1150 #define STORED_SEQS_MASK (STORED_SEQS-1)
1151 #define ADVANCED_SEQS 4
1152 seq_t sequences[STORED_SEQS];
1153 int const seqAdvance = MIN(nbSeq, ADVANCED_SEQS);
1154 seqState_t seqState;
1155 int seqNb;
1156 dctx->fseEntropy = 1;
1157 { int i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
1158 seqState.prefixStart = prefixStart;
1159 seqState.pos = (size_t)(op-prefixStart);
1160 seqState.dictEnd = dictEnd;
1161 assert(dst != NULL);
1162 assert(iend >= ip);
1163 RETURN_ERROR_IF(
1164 ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)),
1165 corruption_detected, "");
1166 ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
1167 ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
1168 ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
1169
1170 /* prepare in advance */
1171 for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && (seqNb<seqAdvance); seqNb++) {
1172 sequences[seqNb] = ZSTD_decodeSequence(&seqState, isLongOffset, ZSTD_p_prefetch);
1173 PREFETCH_L1(sequences[seqNb].match); PREFETCH_L1(sequences[seqNb].match + sequences[seqNb].matchLength - 1); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
1174 }
1175 RETURN_ERROR_IF(seqNb<seqAdvance, corruption_detected, "");
1176
1177 /* decode and decompress */
1178 for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb<nbSeq) ; seqNb++) {
1179 seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset, ZSTD_p_prefetch);
1180 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
1181 #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
1182 assert(!ZSTD_isError(oneSeqSize));
1183 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart);
1184 #endif
1185 if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
1186 PREFETCH_L1(sequence.match); PREFETCH_L1(sequence.match + sequence.matchLength - 1); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
1187 sequences[seqNb & STORED_SEQS_MASK] = sequence;
1188 op += oneSeqSize;
1189 }
1190 RETURN_ERROR_IF(seqNb<nbSeq, corruption_detected, "");
1191
1192 /* finish queue */
1193 seqNb -= seqAdvance;
1194 for ( ; seqNb<nbSeq ; seqNb++) {
1195 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequences[seqNb&STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
1196 #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
1197 assert(!ZSTD_isError(oneSeqSize));
1198 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart);
1199 #endif
1200 if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
1201 op += oneSeqSize;
1202 }
1203
1204 /* save reps for next block */
1205 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
1206 }
1207
1208 /* last literal segment */
1209 { size_t const lastLLSize = litEnd - litPtr;
1210 RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
1211 if (op != NULL) {
1212 memcpy(op, litPtr, lastLLSize);
1213 op += lastLLSize;
1214 }
1215 }
1216
1217 return op-ostart;
1218 }
1219
1220 static size_t
ZSTD_decompressSequencesLong_default(ZSTD_DCtx * dctx,void * dst,size_t maxDstSize,const void * seqStart,size_t seqSize,int nbSeq,const ZSTD_longOffset_e isLongOffset,const int frame)1221 ZSTD_decompressSequencesLong_default(ZSTD_DCtx* dctx,
1222 void* dst, size_t maxDstSize,
1223 const void* seqStart, size_t seqSize, int nbSeq,
1224 const ZSTD_longOffset_e isLongOffset,
1225 const int frame)
1226 {
1227 return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
1228 }
1229 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
1230
1231
1232
1233 #if DYNAMIC_BMI2
1234
1235 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
1236 static TARGET_ATTRIBUTE("bmi2") size_t
1237 DONT_VECTORIZE
ZSTD_decompressSequences_bmi2(ZSTD_DCtx * dctx,void * dst,size_t maxDstSize,const void * seqStart,size_t seqSize,int nbSeq,const ZSTD_longOffset_e isLongOffset,const int frame)1238 ZSTD_decompressSequences_bmi2(ZSTD_DCtx* dctx,
1239 void* dst, size_t maxDstSize,
1240 const void* seqStart, size_t seqSize, int nbSeq,
1241 const ZSTD_longOffset_e isLongOffset,
1242 const int frame)
1243 {
1244 return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
1245 }
1246 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
1247
1248 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
1249 static TARGET_ATTRIBUTE("bmi2") size_t
ZSTD_decompressSequencesLong_bmi2(ZSTD_DCtx * dctx,void * dst,size_t maxDstSize,const void * seqStart,size_t seqSize,int nbSeq,const ZSTD_longOffset_e isLongOffset,const int frame)1250 ZSTD_decompressSequencesLong_bmi2(ZSTD_DCtx* dctx,
1251 void* dst, size_t maxDstSize,
1252 const void* seqStart, size_t seqSize, int nbSeq,
1253 const ZSTD_longOffset_e isLongOffset,
1254 const int frame)
1255 {
1256 return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
1257 }
1258 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
1259
1260 #endif /* DYNAMIC_BMI2 */
1261
1262 typedef size_t (*ZSTD_decompressSequences_t)(
1263 ZSTD_DCtx* dctx,
1264 void* dst, size_t maxDstSize,
1265 const void* seqStart, size_t seqSize, int nbSeq,
1266 const ZSTD_longOffset_e isLongOffset,
1267 const int frame);
1268
1269 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
1270 static size_t
ZSTD_decompressSequences(ZSTD_DCtx * dctx,void * dst,size_t maxDstSize,const void * seqStart,size_t seqSize,int nbSeq,const ZSTD_longOffset_e isLongOffset,const int frame)1271 ZSTD_decompressSequences(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize,
1272 const void* seqStart, size_t seqSize, int nbSeq,
1273 const ZSTD_longOffset_e isLongOffset,
1274 const int frame)
1275 {
1276 DEBUGLOG(5, "ZSTD_decompressSequences");
1277 #if DYNAMIC_BMI2
1278 if (dctx->bmi2) {
1279 return ZSTD_decompressSequences_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
1280 }
1281 #endif
1282 return ZSTD_decompressSequences_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
1283 }
1284 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
1285
1286
1287 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
1288 /* ZSTD_decompressSequencesLong() :
1289 * decompression function triggered when a minimum share of offsets is considered "long",
1290 * aka out of cache.
1291 * note : "long" definition seems overloaded here, sometimes meaning "wider than bitstream register", and sometimes meaning "farther than memory cache distance".
1292 * This function will try to mitigate main memory latency through the use of prefetching */
1293 static size_t
ZSTD_decompressSequencesLong(ZSTD_DCtx * dctx,void * dst,size_t maxDstSize,const void * seqStart,size_t seqSize,int nbSeq,const ZSTD_longOffset_e isLongOffset,const int frame)1294 ZSTD_decompressSequencesLong(ZSTD_DCtx* dctx,
1295 void* dst, size_t maxDstSize,
1296 const void* seqStart, size_t seqSize, int nbSeq,
1297 const ZSTD_longOffset_e isLongOffset,
1298 const int frame)
1299 {
1300 DEBUGLOG(5, "ZSTD_decompressSequencesLong");
1301 #if DYNAMIC_BMI2
1302 if (dctx->bmi2) {
1303 return ZSTD_decompressSequencesLong_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
1304 }
1305 #endif
1306 return ZSTD_decompressSequencesLong_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
1307 }
1308 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
1309
1310
1311
1312 #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
1313 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
1314 /* ZSTD_getLongOffsetsShare() :
1315 * condition : offTable must be valid
1316 * @return : "share" of long offsets (arbitrarily defined as > (1<<23))
1317 * compared to maximum possible of (1<<OffFSELog) */
1318 static unsigned
ZSTD_getLongOffsetsShare(const ZSTD_seqSymbol * offTable)1319 ZSTD_getLongOffsetsShare(const ZSTD_seqSymbol* offTable)
1320 {
1321 const void* ptr = offTable;
1322 U32 const tableLog = ((const ZSTD_seqSymbol_header*)ptr)[0].tableLog;
1323 const ZSTD_seqSymbol* table = offTable + 1;
1324 U32 const max = 1 << tableLog;
1325 U32 u, total = 0;
1326 DEBUGLOG(5, "ZSTD_getLongOffsetsShare: (tableLog=%u)", tableLog);
1327
1328 assert(max <= (1 << OffFSELog)); /* max not too large */
1329 for (u=0; u<max; u++) {
1330 if (table[u].nbAdditionalBits > 22) total += 1;
1331 }
1332
1333 assert(tableLog <= OffFSELog);
1334 total <<= (OffFSELog - tableLog); /* scale to OffFSELog */
1335
1336 return total;
1337 }
1338 #endif
1339
1340 size_t
ZSTD_decompressBlock_internal(ZSTD_DCtx * dctx,void * dst,size_t dstCapacity,const void * src,size_t srcSize,const int frame)1341 ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
1342 void* dst, size_t dstCapacity,
1343 const void* src, size_t srcSize, const int frame)
1344 { /* blockType == blockCompressed */
1345 const BYTE* ip = (const BYTE*)src;
1346 /* isLongOffset must be true if there are long offsets.
1347 * Offsets are long if they are larger than 2^STREAM_ACCUMULATOR_MIN.
1348 * We don't expect that to be the case in 64-bit mode.
1349 * In block mode, window size is not known, so we have to be conservative.
1350 * (note: but it could be evaluated from current-lowLimit)
1351 */
1352 ZSTD_longOffset_e const isLongOffset = (ZSTD_longOffset_e)(MEM_32bits() && (!frame || (dctx->fParams.windowSize > (1ULL << STREAM_ACCUMULATOR_MIN))));
1353 DEBUGLOG(5, "ZSTD_decompressBlock_internal (size : %u)", (U32)srcSize);
1354
1355 RETURN_ERROR_IF(srcSize >= ZSTD_BLOCKSIZE_MAX, srcSize_wrong, "");
1356
1357 /* Decode literals section */
1358 { size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize);
1359 DEBUGLOG(5, "ZSTD_decodeLiteralsBlock : %u", (U32)litCSize);
1360 if (ZSTD_isError(litCSize)) return litCSize;
1361 ip += litCSize;
1362 srcSize -= litCSize;
1363 }
1364
1365 /* Build Decoding Tables */
1366 {
1367 /* These macros control at build-time which decompressor implementation
1368 * we use. If neither is defined, we do some inspection and dispatch at
1369 * runtime.
1370 */
1371 #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
1372 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
1373 int usePrefetchDecoder = dctx->ddictIsCold;
1374 #endif
1375 int nbSeq;
1376 size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize);
1377 if (ZSTD_isError(seqHSize)) return seqHSize;
1378 ip += seqHSize;
1379 srcSize -= seqHSize;
1380
1381 RETURN_ERROR_IF(dst == NULL && nbSeq > 0, dstSize_tooSmall, "NULL not handled");
1382
1383 #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
1384 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
1385 if ( !usePrefetchDecoder
1386 && (!frame || (dctx->fParams.windowSize > (1<<24)))
1387 && (nbSeq>ADVANCED_SEQS) ) { /* could probably use a larger nbSeq limit */
1388 U32 const shareLongOffsets = ZSTD_getLongOffsetsShare(dctx->OFTptr);
1389 U32 const minShare = MEM_64bits() ? 7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */
1390 usePrefetchDecoder = (shareLongOffsets >= minShare);
1391 }
1392 #endif
1393
1394 dctx->ddictIsCold = 0;
1395
1396 #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
1397 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
1398 if (usePrefetchDecoder)
1399 #endif
1400 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
1401 return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame);
1402 #endif
1403
1404 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
1405 /* else */
1406 return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame);
1407 #endif
1408 }
1409 }
1410
1411
ZSTD_checkContinuity(ZSTD_DCtx * dctx,const void * dst)1412 void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst)
1413 {
1414 if (dst != dctx->previousDstEnd) { /* not contiguous */
1415 dctx->dictEnd = dctx->previousDstEnd;
1416 dctx->virtualStart = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->prefixStart));
1417 dctx->prefixStart = dst;
1418 dctx->previousDstEnd = dst;
1419 }
1420 }
1421
1422
ZSTD_decompressBlock(ZSTD_DCtx * dctx,void * dst,size_t dstCapacity,const void * src,size_t srcSize)1423 size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx,
1424 void* dst, size_t dstCapacity,
1425 const void* src, size_t srcSize)
1426 {
1427 size_t dSize;
1428 ZSTD_checkContinuity(dctx, dst);
1429 dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize, /* frame */ 0);
1430 dctx->previousDstEnd = (char*)dst + dSize;
1431 return dSize;
1432 }
1433