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1/*
2 * LZ4 - Fast LZ compression algorithm
3 * Copyright (C) 2011 - 2016, Yann Collet.
4 * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
15 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
16 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
17 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
18 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
19 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
20 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 * You can contact the author at :
26 * - LZ4 homepage : http://www.lz4.org
27 * - LZ4 source repository : https://github.com/lz4/lz4
28 *
29 * Changed for kernel usage by:
30 * Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
31 */
32
33/*-************************************
34 * Dependencies
35 **************************************/
36#include <linux/lz4.h>
37#include "lz4defs.h"
38#include <linux/init.h>
39#include <linux/module.h>
40#include <linux/kernel.h>
41#include <asm/unaligned.h>
42
43/*-*****************************
44 * Decompression functions
45 *******************************/
46
47#define DEBUGLOG(l, ...) {} /* disabled */
48
49#ifndef assert
50#define assert(condition) ((void)0)
51#endif
52
53/*
54 * LZ4_decompress_generic() :
55 * This generic decompression function covers all use cases.
56 * It shall be instantiated several times, using different sets of directives.
57 * Note that it is important for performance that this function really get inlined,
58 * in order to remove useless branches during compilation optimization.
59 */
60static FORCE_INLINE int LZ4_decompress_generic(
61 const char * const src,
62 char * const dst,
63 int srcSize,
64 /*
65 * If endOnInput == endOnInputSize,
66 * this value is `dstCapacity`
67 */
68 int outputSize,
69 /* endOnOutputSize, endOnInputSize */
70 endCondition_directive endOnInput,
71 /* full, partial */
72 earlyEnd_directive partialDecoding,
73 /* noDict, withPrefix64k, usingExtDict */
74 dict_directive dict,
75 /* always <= dst, == dst when no prefix */
76 const BYTE * const lowPrefix,
77 /* only if dict == usingExtDict */
78 const BYTE * const dictStart,
79 /* note : = 0 if noDict */
80 const size_t dictSize
81 )
82{
83 const BYTE *ip = (const BYTE *) src;
84 const BYTE * const iend = ip + srcSize;
85
86 BYTE *op = (BYTE *) dst;
87 BYTE * const oend = op + outputSize;
88 BYTE *cpy;
89
90 const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize;
91 static const unsigned int inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4};
92 static const int dec64table[8] = {0, 0, 0, -1, -4, 1, 2, 3};
93
94 const int safeDecode = (endOnInput == endOnInputSize);
95 const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB)));
96
97 /* Set up the "end" pointers for the shortcut. */
98 const BYTE *const shortiend = iend -
99 (endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/;
100 const BYTE *const shortoend = oend -
101 (endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/;
102
103 DEBUGLOG(5, "%s (srcSize:%i, dstSize:%i)", __func__,
104 srcSize, outputSize);
105
106 /* Special cases */
107 assert(lowPrefix <= op);
108 assert(src != NULL);
109
110 /* Empty output buffer */
111 if ((endOnInput) && (unlikely(outputSize == 0)))
112 return ((srcSize == 1) && (*ip == 0)) ? 0 : -1;
113
114 if ((!endOnInput) && (unlikely(outputSize == 0)))
115 return (*ip == 0 ? 1 : -1);
116
117 if ((endOnInput) && unlikely(srcSize == 0))
118 return -1;
119
120 /* Main Loop : decode sequences */
121 while (1) {
122 size_t length;
123 const BYTE *match;
124 size_t offset;
125
126 /* get literal length */
127 unsigned int const token = *ip++;
128 length = token>>ML_BITS;
129
130 /* ip < iend before the increment */
131 assert(!endOnInput || ip <= iend);
132
133 /*
134 * A two-stage shortcut for the most common case:
135 * 1) If the literal length is 0..14, and there is enough
136 * space, enter the shortcut and copy 16 bytes on behalf
137 * of the literals (in the fast mode, only 8 bytes can be
138 * safely copied this way).
139 * 2) Further if the match length is 4..18, copy 18 bytes
140 * in a similar manner; but we ensure that there's enough
141 * space in the output for those 18 bytes earlier, upon
142 * entering the shortcut (in other words, there is a
143 * combined check for both stages).
144 */
145 if ((endOnInput ? length != RUN_MASK : length <= 8)
146 /*
147 * strictly "less than" on input, to re-enter
148 * the loop with at least one byte
149 */
150 && likely((endOnInput ? ip < shortiend : 1) &
151 (op <= shortoend))) {
152 /* Copy the literals */
153 memcpy(op, ip, endOnInput ? 16 : 8);
154 op += length; ip += length;
155
156 /*
157 * The second stage:
158 * prepare for match copying, decode full info.
159 * If it doesn't work out, the info won't be wasted.
160 */
161 length = token & ML_MASK; /* match length */
162 offset = LZ4_readLE16(ip);
163 ip += 2;
164 match = op - offset;
165 assert(match <= op); /* check overflow */
166
167 /* Do not deal with overlapping matches. */
168 if ((length != ML_MASK) &&
169 (offset >= 8) &&
170 (dict == withPrefix64k || match >= lowPrefix)) {
171 /* Copy the match. */
172 memcpy(op + 0, match + 0, 8);
173 memcpy(op + 8, match + 8, 8);
174 memcpy(op + 16, match + 16, 2);
175 op += length + MINMATCH;
176 /* Both stages worked, load the next token. */
177 continue;
178 }
179
180 /*
181 * The second stage didn't work out, but the info
182 * is ready. Propel it right to the point of match
183 * copying.
184 */
185 goto _copy_match;
186 }
187
188 /* decode literal length */
189 if (length == RUN_MASK) {
190 unsigned int s;
191
192 if (unlikely(endOnInput ? ip >= iend - RUN_MASK : 0)) {
193 /* overflow detection */
194 goto _output_error;
195 }
196 do {
197 s = *ip++;
198 length += s;
199 } while (likely(endOnInput
200 ? ip < iend - RUN_MASK
201 : 1) & (s == 255));
202
203 if ((safeDecode)
204 && unlikely((uptrval)(op) +
205 length < (uptrval)(op))) {
206 /* overflow detection */
207 goto _output_error;
208 }
209 if ((safeDecode)
210 && unlikely((uptrval)(ip) +
211 length < (uptrval)(ip))) {
212 /* overflow detection */
213 goto _output_error;
214 }
215 }
216
217 /* copy literals */
218 cpy = op + length;
219 LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH);
220
221 if (((endOnInput) && ((cpy > oend - MFLIMIT)
222 || (ip + length > iend - (2 + 1 + LASTLITERALS))))
223 || ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) {
224 if (partialDecoding) {
225 if (cpy > oend) {
226 /*
227 * Partial decoding :
228 * stop in the middle of literal segment
229 */
230 cpy = oend;
231 length = oend - op;
232 }
233 if ((endOnInput)
234 && (ip + length > iend)) {
235 /*
236 * Error :
237 * read attempt beyond
238 * end of input buffer
239 */
240 goto _output_error;
241 }
242 } else {
243 if ((!endOnInput)
244 && (cpy != oend)) {
245 /*
246 * Error :
247 * block decoding must
248 * stop exactly there
249 */
250 goto _output_error;
251 }
252 if ((endOnInput)
253 && ((ip + length != iend)
254 || (cpy > oend))) {
255 /*
256 * Error :
257 * input must be consumed
258 */
259 goto _output_error;
260 }
261 }
262
263 memcpy(op, ip, length);
264 ip += length;
265 op += length;
266
267 /* Necessarily EOF, due to parsing restrictions */
268 if (!partialDecoding || (cpy == oend))
269 break;
270 } else {
271 /* may overwrite up to WILDCOPYLENGTH beyond cpy */
272 LZ4_wildCopy(op, ip, cpy);
273 ip += length;
274 op = cpy;
275 }
276
277 /* get offset */
278 offset = LZ4_readLE16(ip);
279 ip += 2;
280 match = op - offset;
281
282 /* get matchlength */
283 length = token & ML_MASK;
284
285_copy_match:
286 if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) {
287 /* Error : offset outside buffers */
288 goto _output_error;
289 }
290
291 /* costs ~1%; silence an msan warning when offset == 0 */
292 /*
293 * note : when partialDecoding, there is no guarantee that
294 * at least 4 bytes remain available in output buffer
295 */
296 if (!partialDecoding) {
297 assert(oend > op);
298 assert(oend - op >= 4);
299
300 LZ4_write32(op, (U32)offset);
301 }
302
303 if (length == ML_MASK) {
304 unsigned int s;
305
306 do {
307 s = *ip++;
308
309 if ((endOnInput) && (ip > iend - LASTLITERALS))
310 goto _output_error;
311
312 length += s;
313 } while (s == 255);
314
315 if ((safeDecode)
316 && unlikely(
317 (uptrval)(op) + length < (uptrval)op)) {
318 /* overflow detection */
319 goto _output_error;
320 }
321 }
322
323 length += MINMATCH;
324
325 /* match starting within external dictionary */
326 if ((dict == usingExtDict) && (match < lowPrefix)) {
327 if (unlikely(op + length > oend - LASTLITERALS)) {
328 /* doesn't respect parsing restriction */
329 if (!partialDecoding)
330 goto _output_error;
331 length = min(length, (size_t)(oend - op));
332 }
333
334 if (length <= (size_t)(lowPrefix - match)) {
335 /*
336 * match fits entirely within external
337 * dictionary : just copy
338 */
339 memmove(op, dictEnd - (lowPrefix - match),
340 length);
341 op += length;
342 } else {
343 /*
344 * match stretches into both external
345 * dictionary and current block
346 */
347 size_t const copySize = (size_t)(lowPrefix - match);
348 size_t const restSize = length - copySize;
349
350 memcpy(op, dictEnd - copySize, copySize);
351 op += copySize;
352 if (restSize > (size_t)(op - lowPrefix)) {
353 /* overlap copy */
354 BYTE * const endOfMatch = op + restSize;
355 const BYTE *copyFrom = lowPrefix;
356
357 while (op < endOfMatch)
358 *op++ = *copyFrom++;
359 } else {
360 memcpy(op, lowPrefix, restSize);
361 op += restSize;
362 }
363 }
364 continue;
365 }
366
367 /* copy match within block */
368 cpy = op + length;
369
370 /*
371 * partialDecoding :
372 * may not respect endBlock parsing restrictions
373 */
374 assert(op <= oend);
375 if (partialDecoding &&
376 (cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
377 size_t const mlen = min(length, (size_t)(oend - op));
378 const BYTE * const matchEnd = match + mlen;
379 BYTE * const copyEnd = op + mlen;
380
381 if (matchEnd > op) {
382 /* overlap copy */
383 while (op < copyEnd)
384 *op++ = *match++;
385 } else {
386 memcpy(op, match, mlen);
387 }
388 op = copyEnd;
389 if (op == oend)
390 break;
391 continue;
392 }
393
394 if (unlikely(offset < 8)) {
395 op[0] = match[0];
396 op[1] = match[1];
397 op[2] = match[2];
398 op[3] = match[3];
399 match += inc32table[offset];
400 memcpy(op + 4, match, 4);
401 match -= dec64table[offset];
402 } else {
403 LZ4_copy8(op, match);
404 match += 8;
405 }
406
407 op += 8;
408
409 if (unlikely(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
410 BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
411
412 if (cpy > oend - LASTLITERALS) {
413 /*
414 * Error : last LASTLITERALS bytes
415 * must be literals (uncompressed)
416 */
417 goto _output_error;
418 }
419
420 if (op < oCopyLimit) {
421 LZ4_wildCopy(op, match, oCopyLimit);
422 match += oCopyLimit - op;
423 op = oCopyLimit;
424 }
425 while (op < cpy)
426 *op++ = *match++;
427 } else {
428 LZ4_copy8(op, match);
429 if (length > 16)
430 LZ4_wildCopy(op + 8, match + 8, cpy);
431 }
432 op = cpy; /* wildcopy correction */
433 }
434
435 /* end of decoding */
436 if (endOnInput) {
437 /* Nb of output bytes decoded */
438 return (int) (((char *)op) - dst);
439 } else {
440 /* Nb of input bytes read */
441 return (int) (((const char *)ip) - src);
442 }
443
444 /* Overflow error detected */
445_output_error:
446 return (int) (-(((const char *)ip) - src)) - 1;
447}
448
449int LZ4_decompress_safe(const char *source, char *dest,
450 int compressedSize, int maxDecompressedSize)
451{
452 return LZ4_decompress_generic(source, dest,
453 compressedSize, maxDecompressedSize,
454 endOnInputSize, decode_full_block,
455 noDict, (BYTE *)dest, NULL, 0);
456}
457
458int LZ4_decompress_safe_partial(const char *src, char *dst,
459 int compressedSize, int targetOutputSize, int dstCapacity)
460{
461 dstCapacity = min(targetOutputSize, dstCapacity);
462 return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity,
463 endOnInputSize, partial_decode,
464 noDict, (BYTE *)dst, NULL, 0);
465}
466
467int LZ4_decompress_fast(const char *source, char *dest, int originalSize)
468{
469 return LZ4_decompress_generic(source, dest, 0, originalSize,
470 endOnOutputSize, decode_full_block,
471 withPrefix64k,
472 (BYTE *)dest - 64 * KB, NULL, 0);
473}
474
475/* ===== Instantiate a few more decoding cases, used more than once. ===== */
476
477int LZ4_decompress_safe_withPrefix64k(const char *source, char *dest,
478 int compressedSize, int maxOutputSize)
479{
480 return LZ4_decompress_generic(source, dest,
481 compressedSize, maxOutputSize,
482 endOnInputSize, decode_full_block,
483 withPrefix64k,
484 (BYTE *)dest - 64 * KB, NULL, 0);
485}
486
487static int LZ4_decompress_safe_withSmallPrefix(const char *source, char *dest,
488 int compressedSize,
489 int maxOutputSize,
490 size_t prefixSize)
491{
492 return LZ4_decompress_generic(source, dest,
493 compressedSize, maxOutputSize,
494 endOnInputSize, decode_full_block,
495 noDict,
496 (BYTE *)dest - prefixSize, NULL, 0);
497}
498
499int LZ4_decompress_safe_forceExtDict(const char *source, char *dest,
500 int compressedSize, int maxOutputSize,
501 const void *dictStart, size_t dictSize)
502{
503 return LZ4_decompress_generic(source, dest,
504 compressedSize, maxOutputSize,
505 endOnInputSize, decode_full_block,
506 usingExtDict, (BYTE *)dest,
507 (const BYTE *)dictStart, dictSize);
508}
509
510static int LZ4_decompress_fast_extDict(const char *source, char *dest,
511 int originalSize,
512 const void *dictStart, size_t dictSize)
513{
514 return LZ4_decompress_generic(source, dest,
515 0, originalSize,
516 endOnOutputSize, decode_full_block,
517 usingExtDict, (BYTE *)dest,
518 (const BYTE *)dictStart, dictSize);
519}
520
521/*
522 * The "double dictionary" mode, for use with e.g. ring buffers: the first part
523 * of the dictionary is passed as prefix, and the second via dictStart + dictSize.
524 * These routines are used only once, in LZ4_decompress_*_continue().
525 */
526static FORCE_INLINE
527int LZ4_decompress_safe_doubleDict(const char *source, char *dest,
528 int compressedSize, int maxOutputSize,
529 size_t prefixSize,
530 const void *dictStart, size_t dictSize)
531{
532 return LZ4_decompress_generic(source, dest,
533 compressedSize, maxOutputSize,
534 endOnInputSize, decode_full_block,
535 usingExtDict, (BYTE *)dest - prefixSize,
536 (const BYTE *)dictStart, dictSize);
537}
538
539static FORCE_INLINE
540int LZ4_decompress_fast_doubleDict(const char *source, char *dest,
541 int originalSize, size_t prefixSize,
542 const void *dictStart, size_t dictSize)
543{
544 return LZ4_decompress_generic(source, dest,
545 0, originalSize,
546 endOnOutputSize, decode_full_block,
547 usingExtDict, (BYTE *)dest - prefixSize,
548 (const BYTE *)dictStart, dictSize);
549}
550
551/* ===== streaming decompression functions ===== */
552
553int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
554 const char *dictionary, int dictSize)
555{
556 LZ4_streamDecode_t_internal *lz4sd =
557 &LZ4_streamDecode->internal_donotuse;
558
559 lz4sd->prefixSize = (size_t) dictSize;
560 lz4sd->prefixEnd = (const BYTE *) dictionary + dictSize;
561 lz4sd->externalDict = NULL;
562 lz4sd->extDictSize = 0;
563 return 1;
564}
565
566/*
567 * *_continue() :
568 * These decoding functions allow decompression of multiple blocks
569 * in "streaming" mode.
570 * Previously decoded blocks must still be available at the memory
571 * position where they were decoded.
572 * If it's not possible, save the relevant part of
573 * decoded data into a safe buffer,
574 * and indicate where it stands using LZ4_setStreamDecode()
575 */
576int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
577 const char *source, char *dest, int compressedSize, int maxOutputSize)
578{
579 LZ4_streamDecode_t_internal *lz4sd =
580 &LZ4_streamDecode->internal_donotuse;
581 int result;
582
583 if (lz4sd->prefixSize == 0) {
584 /* The first call, no dictionary yet. */
585 assert(lz4sd->extDictSize == 0);
586 result = LZ4_decompress_safe(source, dest,
587 compressedSize, maxOutputSize);
588 if (result <= 0)
589 return result;
590 lz4sd->prefixSize = result;
591 lz4sd->prefixEnd = (BYTE *)dest + result;
592 } else if (lz4sd->prefixEnd == (BYTE *)dest) {
593 /* They're rolling the current segment. */
594 if (lz4sd->prefixSize >= 64 * KB - 1)
595 result = LZ4_decompress_safe_withPrefix64k(source, dest,
596 compressedSize, maxOutputSize);
597 else if (lz4sd->extDictSize == 0)
598 result = LZ4_decompress_safe_withSmallPrefix(source,
599 dest, compressedSize, maxOutputSize,
600 lz4sd->prefixSize);
601 else
602 result = LZ4_decompress_safe_doubleDict(source, dest,
603 compressedSize, maxOutputSize,
604 lz4sd->prefixSize,
605 lz4sd->externalDict, lz4sd->extDictSize);
606 if (result <= 0)
607 return result;
608 lz4sd->prefixSize += result;
609 lz4sd->prefixEnd += result;
610 } else {
611 /*
612 * The buffer wraps around, or they're
613 * switching to another buffer.
614 */
615 lz4sd->extDictSize = lz4sd->prefixSize;
616 lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
617 result = LZ4_decompress_safe_forceExtDict(source, dest,
618 compressedSize, maxOutputSize,
619 lz4sd->externalDict, lz4sd->extDictSize);
620 if (result <= 0)
621 return result;
622 lz4sd->prefixSize = result;
623 lz4sd->prefixEnd = (BYTE *)dest + result;
624 }
625
626 return result;
627}
628
629int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
630 const char *source, char *dest, int originalSize)
631{
632 LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
633 int result;
634
635 if (lz4sd->prefixSize == 0) {
636 assert(lz4sd->extDictSize == 0);
637 result = LZ4_decompress_fast(source, dest, originalSize);
638 if (result <= 0)
639 return result;
640 lz4sd->prefixSize = originalSize;
641 lz4sd->prefixEnd = (BYTE *)dest + originalSize;
642 } else if (lz4sd->prefixEnd == (BYTE *)dest) {
643 if (lz4sd->prefixSize >= 64 * KB - 1 ||
644 lz4sd->extDictSize == 0)
645 result = LZ4_decompress_fast(source, dest,
646 originalSize);
647 else
648 result = LZ4_decompress_fast_doubleDict(source, dest,
649 originalSize, lz4sd->prefixSize,
650 lz4sd->externalDict, lz4sd->extDictSize);
651 if (result <= 0)
652 return result;
653 lz4sd->prefixSize += originalSize;
654 lz4sd->prefixEnd += originalSize;
655 } else {
656 lz4sd->extDictSize = lz4sd->prefixSize;
657 lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
658 result = LZ4_decompress_fast_extDict(source, dest,
659 originalSize, lz4sd->externalDict, lz4sd->extDictSize);
660 if (result <= 0)
661 return result;
662 lz4sd->prefixSize = originalSize;
663 lz4sd->prefixEnd = (BYTE *)dest + originalSize;
664 }
665 return result;
666}
667
668int LZ4_decompress_safe_usingDict(const char *source, char *dest,
669 int compressedSize, int maxOutputSize,
670 const char *dictStart, int dictSize)
671{
672 if (dictSize == 0)
673 return LZ4_decompress_safe(source, dest,
674 compressedSize, maxOutputSize);
675 if (dictStart+dictSize == dest) {
676 if (dictSize >= 64 * KB - 1)
677 return LZ4_decompress_safe_withPrefix64k(source, dest,
678 compressedSize, maxOutputSize);
679 return LZ4_decompress_safe_withSmallPrefix(source, dest,
680 compressedSize, maxOutputSize, dictSize);
681 }
682 return LZ4_decompress_safe_forceExtDict(source, dest,
683 compressedSize, maxOutputSize, dictStart, dictSize);
684}
685
686int LZ4_decompress_fast_usingDict(const char *source, char *dest,
687 int originalSize,
688 const char *dictStart, int dictSize)
689{
690 if (dictSize == 0 || dictStart + dictSize == dest)
691 return LZ4_decompress_fast(source, dest, originalSize);
692
693 return LZ4_decompress_fast_extDict(source, dest, originalSize,
694 dictStart, dictSize);
695}
696
697#ifndef STATIC
698EXPORT_SYMBOL(LZ4_decompress_safe);
699EXPORT_SYMBOL(LZ4_decompress_safe_partial);
700EXPORT_SYMBOL(LZ4_decompress_fast);
701EXPORT_SYMBOL(LZ4_setStreamDecode);
702EXPORT_SYMBOL(LZ4_decompress_safe_continue);
703EXPORT_SYMBOL(LZ4_decompress_fast_continue);
704EXPORT_SYMBOL(LZ4_decompress_safe_usingDict);
705EXPORT_SYMBOL(LZ4_decompress_fast_usingDict);
706
707MODULE_LICENSE("Dual BSD/GPL");
708MODULE_DESCRIPTION("LZ4 decompressor");
709#endif
1/*
2 * LZ4 - Fast LZ compression algorithm
3 * Copyright (C) 2011 - 2016, Yann Collet.
4 * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
15 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
16 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
17 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
18 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
19 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
20 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 * You can contact the author at :
26 * - LZ4 homepage : http://www.lz4.org
27 * - LZ4 source repository : https://github.com/lz4/lz4
28 *
29 * Changed for kernel usage by:
30 * Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
31 */
32
33/*-************************************
34 * Dependencies
35 **************************************/
36#include <linux/lz4.h>
37#include "lz4defs.h"
38#include <linux/init.h>
39#include <linux/module.h>
40#include <linux/kernel.h>
41#include <linux/unaligned.h>
42
43/*-*****************************
44 * Decompression functions
45 *******************************/
46
47#define DEBUGLOG(l, ...) {} /* disabled */
48
49#ifndef assert
50#define assert(condition) ((void)0)
51#endif
52
53/*
54 * LZ4_decompress_generic() :
55 * This generic decompression function covers all use cases.
56 * It shall be instantiated several times, using different sets of directives.
57 * Note that it is important for performance that this function really get inlined,
58 * in order to remove useless branches during compilation optimization.
59 */
60static FORCE_INLINE int LZ4_decompress_generic(
61 const char * const src,
62 char * const dst,
63 int srcSize,
64 /*
65 * If endOnInput == endOnInputSize,
66 * this value is `dstCapacity`
67 */
68 int outputSize,
69 /* endOnOutputSize, endOnInputSize */
70 endCondition_directive endOnInput,
71 /* full, partial */
72 earlyEnd_directive partialDecoding,
73 /* noDict, withPrefix64k, usingExtDict */
74 dict_directive dict,
75 /* always <= dst, == dst when no prefix */
76 const BYTE * const lowPrefix,
77 /* only if dict == usingExtDict */
78 const BYTE * const dictStart,
79 /* note : = 0 if noDict */
80 const size_t dictSize
81 )
82{
83 const BYTE *ip = (const BYTE *) src;
84 const BYTE * const iend = ip + srcSize;
85
86 BYTE *op = (BYTE *) dst;
87 BYTE * const oend = op + outputSize;
88 BYTE *cpy;
89
90 const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize;
91 static const unsigned int inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4};
92 static const int dec64table[8] = {0, 0, 0, -1, -4, 1, 2, 3};
93
94 const int safeDecode = (endOnInput == endOnInputSize);
95 const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB)));
96
97 /* Set up the "end" pointers for the shortcut. */
98 const BYTE *const shortiend = iend -
99 (endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/;
100 const BYTE *const shortoend = oend -
101 (endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/;
102
103 DEBUGLOG(5, "%s (srcSize:%i, dstSize:%i)", __func__,
104 srcSize, outputSize);
105
106 /* Special cases */
107 assert(lowPrefix <= op);
108 assert(src != NULL);
109
110 /* Empty output buffer */
111 if ((endOnInput) && (unlikely(outputSize == 0)))
112 return ((srcSize == 1) && (*ip == 0)) ? 0 : -1;
113
114 if ((!endOnInput) && (unlikely(outputSize == 0)))
115 return (*ip == 0 ? 1 : -1);
116
117 if ((endOnInput) && unlikely(srcSize == 0))
118 return -1;
119
120 /* Main Loop : decode sequences */
121 while (1) {
122 size_t length;
123 const BYTE *match;
124 size_t offset;
125
126 /* get literal length */
127 unsigned int const token = *ip++;
128 length = token>>ML_BITS;
129
130 /* ip < iend before the increment */
131 assert(!endOnInput || ip <= iend);
132
133 /*
134 * A two-stage shortcut for the most common case:
135 * 1) If the literal length is 0..14, and there is enough
136 * space, enter the shortcut and copy 16 bytes on behalf
137 * of the literals (in the fast mode, only 8 bytes can be
138 * safely copied this way).
139 * 2) Further if the match length is 4..18, copy 18 bytes
140 * in a similar manner; but we ensure that there's enough
141 * space in the output for those 18 bytes earlier, upon
142 * entering the shortcut (in other words, there is a
143 * combined check for both stages).
144 *
145 * The & in the likely() below is intentionally not && so that
146 * some compilers can produce better parallelized runtime code
147 */
148 if ((endOnInput ? length != RUN_MASK : length <= 8)
149 /*
150 * strictly "less than" on input, to re-enter
151 * the loop with at least one byte
152 */
153 && likely((endOnInput ? ip < shortiend : 1) &
154 (op <= shortoend))) {
155 /* Copy the literals */
156 LZ4_memcpy(op, ip, endOnInput ? 16 : 8);
157 op += length; ip += length;
158
159 /*
160 * The second stage:
161 * prepare for match copying, decode full info.
162 * If it doesn't work out, the info won't be wasted.
163 */
164 length = token & ML_MASK; /* match length */
165 offset = LZ4_readLE16(ip);
166 ip += 2;
167 match = op - offset;
168 assert(match <= op); /* check overflow */
169
170 /* Do not deal with overlapping matches. */
171 if ((length != ML_MASK) &&
172 (offset >= 8) &&
173 (dict == withPrefix64k || match >= lowPrefix)) {
174 /* Copy the match. */
175 LZ4_memcpy(op + 0, match + 0, 8);
176 LZ4_memcpy(op + 8, match + 8, 8);
177 LZ4_memcpy(op + 16, match + 16, 2);
178 op += length + MINMATCH;
179 /* Both stages worked, load the next token. */
180 continue;
181 }
182
183 /*
184 * The second stage didn't work out, but the info
185 * is ready. Propel it right to the point of match
186 * copying.
187 */
188 goto _copy_match;
189 }
190
191 /* decode literal length */
192 if (length == RUN_MASK) {
193 unsigned int s;
194
195 if (unlikely(endOnInput ? ip >= iend - RUN_MASK : 0)) {
196 /* overflow detection */
197 goto _output_error;
198 }
199 do {
200 s = *ip++;
201 length += s;
202 } while (likely(endOnInput
203 ? ip < iend - RUN_MASK
204 : 1) & (s == 255));
205
206 if ((safeDecode)
207 && unlikely((uptrval)(op) +
208 length < (uptrval)(op))) {
209 /* overflow detection */
210 goto _output_error;
211 }
212 if ((safeDecode)
213 && unlikely((uptrval)(ip) +
214 length < (uptrval)(ip))) {
215 /* overflow detection */
216 goto _output_error;
217 }
218 }
219
220 /* copy literals */
221 cpy = op + length;
222 LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH);
223
224 if (((endOnInput) && ((cpy > oend - MFLIMIT)
225 || (ip + length > iend - (2 + 1 + LASTLITERALS))))
226 || ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) {
227 if (partialDecoding) {
228 if (cpy > oend) {
229 /*
230 * Partial decoding :
231 * stop in the middle of literal segment
232 */
233 cpy = oend;
234 length = oend - op;
235 }
236 if ((endOnInput)
237 && (ip + length > iend)) {
238 /*
239 * Error :
240 * read attempt beyond
241 * end of input buffer
242 */
243 goto _output_error;
244 }
245 } else {
246 if ((!endOnInput)
247 && (cpy != oend)) {
248 /*
249 * Error :
250 * block decoding must
251 * stop exactly there
252 */
253 goto _output_error;
254 }
255 if ((endOnInput)
256 && ((ip + length != iend)
257 || (cpy > oend))) {
258 /*
259 * Error :
260 * input must be consumed
261 */
262 goto _output_error;
263 }
264 }
265
266 /*
267 * supports overlapping memory regions; only matters
268 * for in-place decompression scenarios
269 */
270 LZ4_memmove(op, ip, length);
271 ip += length;
272 op += length;
273
274 /* Necessarily EOF when !partialDecoding.
275 * When partialDecoding, it is EOF if we've either
276 * filled the output buffer or
277 * can't proceed with reading an offset for following match.
278 */
279 if (!partialDecoding || (cpy == oend) || (ip >= (iend - 2)))
280 break;
281 } else {
282 /* may overwrite up to WILDCOPYLENGTH beyond cpy */
283 LZ4_wildCopy(op, ip, cpy);
284 ip += length;
285 op = cpy;
286 }
287
288 /* get offset */
289 offset = LZ4_readLE16(ip);
290 ip += 2;
291 match = op - offset;
292
293 /* get matchlength */
294 length = token & ML_MASK;
295
296_copy_match:
297 if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) {
298 /* Error : offset outside buffers */
299 goto _output_error;
300 }
301
302 /* costs ~1%; silence an msan warning when offset == 0 */
303 /*
304 * note : when partialDecoding, there is no guarantee that
305 * at least 4 bytes remain available in output buffer
306 */
307 if (!partialDecoding) {
308 assert(oend > op);
309 assert(oend - op >= 4);
310
311 LZ4_write32(op, (U32)offset);
312 }
313
314 if (length == ML_MASK) {
315 unsigned int s;
316
317 do {
318 s = *ip++;
319
320 if ((endOnInput) && (ip > iend - LASTLITERALS))
321 goto _output_error;
322
323 length += s;
324 } while (s == 255);
325
326 if ((safeDecode)
327 && unlikely(
328 (uptrval)(op) + length < (uptrval)op)) {
329 /* overflow detection */
330 goto _output_error;
331 }
332 }
333
334 length += MINMATCH;
335
336 /* match starting within external dictionary */
337 if ((dict == usingExtDict) && (match < lowPrefix)) {
338 if (unlikely(op + length > oend - LASTLITERALS)) {
339 /* doesn't respect parsing restriction */
340 if (!partialDecoding)
341 goto _output_error;
342 length = min(length, (size_t)(oend - op));
343 }
344
345 if (length <= (size_t)(lowPrefix - match)) {
346 /*
347 * match fits entirely within external
348 * dictionary : just copy
349 */
350 memmove(op, dictEnd - (lowPrefix - match),
351 length);
352 op += length;
353 } else {
354 /*
355 * match stretches into both external
356 * dictionary and current block
357 */
358 size_t const copySize = (size_t)(lowPrefix - match);
359 size_t const restSize = length - copySize;
360
361 LZ4_memcpy(op, dictEnd - copySize, copySize);
362 op += copySize;
363 if (restSize > (size_t)(op - lowPrefix)) {
364 /* overlap copy */
365 BYTE * const endOfMatch = op + restSize;
366 const BYTE *copyFrom = lowPrefix;
367
368 while (op < endOfMatch)
369 *op++ = *copyFrom++;
370 } else {
371 LZ4_memcpy(op, lowPrefix, restSize);
372 op += restSize;
373 }
374 }
375 continue;
376 }
377
378 /* copy match within block */
379 cpy = op + length;
380
381 /*
382 * partialDecoding :
383 * may not respect endBlock parsing restrictions
384 */
385 assert(op <= oend);
386 if (partialDecoding &&
387 (cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
388 size_t const mlen = min(length, (size_t)(oend - op));
389 const BYTE * const matchEnd = match + mlen;
390 BYTE * const copyEnd = op + mlen;
391
392 if (matchEnd > op) {
393 /* overlap copy */
394 while (op < copyEnd)
395 *op++ = *match++;
396 } else {
397 LZ4_memcpy(op, match, mlen);
398 }
399 op = copyEnd;
400 if (op == oend)
401 break;
402 continue;
403 }
404
405 if (unlikely(offset < 8)) {
406 op[0] = match[0];
407 op[1] = match[1];
408 op[2] = match[2];
409 op[3] = match[3];
410 match += inc32table[offset];
411 LZ4_memcpy(op + 4, match, 4);
412 match -= dec64table[offset];
413 } else {
414 LZ4_copy8(op, match);
415 match += 8;
416 }
417
418 op += 8;
419
420 if (unlikely(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
421 BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
422
423 if (cpy > oend - LASTLITERALS) {
424 /*
425 * Error : last LASTLITERALS bytes
426 * must be literals (uncompressed)
427 */
428 goto _output_error;
429 }
430
431 if (op < oCopyLimit) {
432 LZ4_wildCopy(op, match, oCopyLimit);
433 match += oCopyLimit - op;
434 op = oCopyLimit;
435 }
436 while (op < cpy)
437 *op++ = *match++;
438 } else {
439 LZ4_copy8(op, match);
440 if (length > 16)
441 LZ4_wildCopy(op + 8, match + 8, cpy);
442 }
443 op = cpy; /* wildcopy correction */
444 }
445
446 /* end of decoding */
447 if (endOnInput) {
448 /* Nb of output bytes decoded */
449 return (int) (((char *)op) - dst);
450 } else {
451 /* Nb of input bytes read */
452 return (int) (((const char *)ip) - src);
453 }
454
455 /* Overflow error detected */
456_output_error:
457 return (int) (-(((const char *)ip) - src)) - 1;
458}
459
460int LZ4_decompress_safe(const char *source, char *dest,
461 int compressedSize, int maxDecompressedSize)
462{
463 return LZ4_decompress_generic(source, dest,
464 compressedSize, maxDecompressedSize,
465 endOnInputSize, decode_full_block,
466 noDict, (BYTE *)dest, NULL, 0);
467}
468
469int LZ4_decompress_safe_partial(const char *src, char *dst,
470 int compressedSize, int targetOutputSize, int dstCapacity)
471{
472 dstCapacity = min(targetOutputSize, dstCapacity);
473 return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity,
474 endOnInputSize, partial_decode,
475 noDict, (BYTE *)dst, NULL, 0);
476}
477
478int LZ4_decompress_fast(const char *source, char *dest, int originalSize)
479{
480 return LZ4_decompress_generic(source, dest, 0, originalSize,
481 endOnOutputSize, decode_full_block,
482 withPrefix64k,
483 (BYTE *)dest - 64 * KB, NULL, 0);
484}
485
486/* ===== Instantiate a few more decoding cases, used more than once. ===== */
487
488static int LZ4_decompress_safe_withPrefix64k(const char *source, char *dest,
489 int compressedSize, int maxOutputSize)
490{
491 return LZ4_decompress_generic(source, dest,
492 compressedSize, maxOutputSize,
493 endOnInputSize, decode_full_block,
494 withPrefix64k,
495 (BYTE *)dest - 64 * KB, NULL, 0);
496}
497
498static int LZ4_decompress_safe_withSmallPrefix(const char *source, char *dest,
499 int compressedSize,
500 int maxOutputSize,
501 size_t prefixSize)
502{
503 return LZ4_decompress_generic(source, dest,
504 compressedSize, maxOutputSize,
505 endOnInputSize, decode_full_block,
506 noDict,
507 (BYTE *)dest - prefixSize, NULL, 0);
508}
509
510static int LZ4_decompress_safe_forceExtDict(const char *source, char *dest,
511 int compressedSize, int maxOutputSize,
512 const void *dictStart, size_t dictSize)
513{
514 return LZ4_decompress_generic(source, dest,
515 compressedSize, maxOutputSize,
516 endOnInputSize, decode_full_block,
517 usingExtDict, (BYTE *)dest,
518 (const BYTE *)dictStart, dictSize);
519}
520
521static int LZ4_decompress_fast_extDict(const char *source, char *dest,
522 int originalSize,
523 const void *dictStart, size_t dictSize)
524{
525 return LZ4_decompress_generic(source, dest,
526 0, originalSize,
527 endOnOutputSize, decode_full_block,
528 usingExtDict, (BYTE *)dest,
529 (const BYTE *)dictStart, dictSize);
530}
531
532/*
533 * The "double dictionary" mode, for use with e.g. ring buffers: the first part
534 * of the dictionary is passed as prefix, and the second via dictStart + dictSize.
535 * These routines are used only once, in LZ4_decompress_*_continue().
536 */
537static FORCE_INLINE
538int LZ4_decompress_safe_doubleDict(const char *source, char *dest,
539 int compressedSize, int maxOutputSize,
540 size_t prefixSize,
541 const void *dictStart, size_t dictSize)
542{
543 return LZ4_decompress_generic(source, dest,
544 compressedSize, maxOutputSize,
545 endOnInputSize, decode_full_block,
546 usingExtDict, (BYTE *)dest - prefixSize,
547 (const BYTE *)dictStart, dictSize);
548}
549
550static FORCE_INLINE
551int LZ4_decompress_fast_doubleDict(const char *source, char *dest,
552 int originalSize, size_t prefixSize,
553 const void *dictStart, size_t dictSize)
554{
555 return LZ4_decompress_generic(source, dest,
556 0, originalSize,
557 endOnOutputSize, decode_full_block,
558 usingExtDict, (BYTE *)dest - prefixSize,
559 (const BYTE *)dictStart, dictSize);
560}
561
562/* ===== streaming decompression functions ===== */
563
564int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
565 const char *dictionary, int dictSize)
566{
567 LZ4_streamDecode_t_internal *lz4sd =
568 &LZ4_streamDecode->internal_donotuse;
569
570 lz4sd->prefixSize = (size_t) dictSize;
571 lz4sd->prefixEnd = (const BYTE *) dictionary + dictSize;
572 lz4sd->externalDict = NULL;
573 lz4sd->extDictSize = 0;
574 return 1;
575}
576
577/*
578 * *_continue() :
579 * These decoding functions allow decompression of multiple blocks
580 * in "streaming" mode.
581 * Previously decoded blocks must still be available at the memory
582 * position where they were decoded.
583 * If it's not possible, save the relevant part of
584 * decoded data into a safe buffer,
585 * and indicate where it stands using LZ4_setStreamDecode()
586 */
587int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
588 const char *source, char *dest, int compressedSize, int maxOutputSize)
589{
590 LZ4_streamDecode_t_internal *lz4sd =
591 &LZ4_streamDecode->internal_donotuse;
592 int result;
593
594 if (lz4sd->prefixSize == 0) {
595 /* The first call, no dictionary yet. */
596 assert(lz4sd->extDictSize == 0);
597 result = LZ4_decompress_safe(source, dest,
598 compressedSize, maxOutputSize);
599 if (result <= 0)
600 return result;
601 lz4sd->prefixSize = result;
602 lz4sd->prefixEnd = (BYTE *)dest + result;
603 } else if (lz4sd->prefixEnd == (BYTE *)dest) {
604 /* They're rolling the current segment. */
605 if (lz4sd->prefixSize >= 64 * KB - 1)
606 result = LZ4_decompress_safe_withPrefix64k(source, dest,
607 compressedSize, maxOutputSize);
608 else if (lz4sd->extDictSize == 0)
609 result = LZ4_decompress_safe_withSmallPrefix(source,
610 dest, compressedSize, maxOutputSize,
611 lz4sd->prefixSize);
612 else
613 result = LZ4_decompress_safe_doubleDict(source, dest,
614 compressedSize, maxOutputSize,
615 lz4sd->prefixSize,
616 lz4sd->externalDict, lz4sd->extDictSize);
617 if (result <= 0)
618 return result;
619 lz4sd->prefixSize += result;
620 lz4sd->prefixEnd += result;
621 } else {
622 /*
623 * The buffer wraps around, or they're
624 * switching to another buffer.
625 */
626 lz4sd->extDictSize = lz4sd->prefixSize;
627 lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
628 result = LZ4_decompress_safe_forceExtDict(source, dest,
629 compressedSize, maxOutputSize,
630 lz4sd->externalDict, lz4sd->extDictSize);
631 if (result <= 0)
632 return result;
633 lz4sd->prefixSize = result;
634 lz4sd->prefixEnd = (BYTE *)dest + result;
635 }
636
637 return result;
638}
639
640int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
641 const char *source, char *dest, int originalSize)
642{
643 LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
644 int result;
645
646 if (lz4sd->prefixSize == 0) {
647 assert(lz4sd->extDictSize == 0);
648 result = LZ4_decompress_fast(source, dest, originalSize);
649 if (result <= 0)
650 return result;
651 lz4sd->prefixSize = originalSize;
652 lz4sd->prefixEnd = (BYTE *)dest + originalSize;
653 } else if (lz4sd->prefixEnd == (BYTE *)dest) {
654 if (lz4sd->prefixSize >= 64 * KB - 1 ||
655 lz4sd->extDictSize == 0)
656 result = LZ4_decompress_fast(source, dest,
657 originalSize);
658 else
659 result = LZ4_decompress_fast_doubleDict(source, dest,
660 originalSize, lz4sd->prefixSize,
661 lz4sd->externalDict, lz4sd->extDictSize);
662 if (result <= 0)
663 return result;
664 lz4sd->prefixSize += originalSize;
665 lz4sd->prefixEnd += originalSize;
666 } else {
667 lz4sd->extDictSize = lz4sd->prefixSize;
668 lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
669 result = LZ4_decompress_fast_extDict(source, dest,
670 originalSize, lz4sd->externalDict, lz4sd->extDictSize);
671 if (result <= 0)
672 return result;
673 lz4sd->prefixSize = originalSize;
674 lz4sd->prefixEnd = (BYTE *)dest + originalSize;
675 }
676 return result;
677}
678
679int LZ4_decompress_safe_usingDict(const char *source, char *dest,
680 int compressedSize, int maxOutputSize,
681 const char *dictStart, int dictSize)
682{
683 if (dictSize == 0)
684 return LZ4_decompress_safe(source, dest,
685 compressedSize, maxOutputSize);
686 if (dictStart+dictSize == dest) {
687 if (dictSize >= 64 * KB - 1)
688 return LZ4_decompress_safe_withPrefix64k(source, dest,
689 compressedSize, maxOutputSize);
690 return LZ4_decompress_safe_withSmallPrefix(source, dest,
691 compressedSize, maxOutputSize, dictSize);
692 }
693 return LZ4_decompress_safe_forceExtDict(source, dest,
694 compressedSize, maxOutputSize, dictStart, dictSize);
695}
696
697int LZ4_decompress_fast_usingDict(const char *source, char *dest,
698 int originalSize,
699 const char *dictStart, int dictSize)
700{
701 if (dictSize == 0 || dictStart + dictSize == dest)
702 return LZ4_decompress_fast(source, dest, originalSize);
703
704 return LZ4_decompress_fast_extDict(source, dest, originalSize,
705 dictStart, dictSize);
706}
707
708#ifndef STATIC
709EXPORT_SYMBOL(LZ4_decompress_safe);
710EXPORT_SYMBOL(LZ4_decompress_safe_partial);
711EXPORT_SYMBOL(LZ4_decompress_fast);
712EXPORT_SYMBOL(LZ4_setStreamDecode);
713EXPORT_SYMBOL(LZ4_decompress_safe_continue);
714EXPORT_SYMBOL(LZ4_decompress_fast_continue);
715EXPORT_SYMBOL(LZ4_decompress_safe_usingDict);
716EXPORT_SYMBOL(LZ4_decompress_fast_usingDict);
717
718MODULE_LICENSE("Dual BSD/GPL");
719MODULE_DESCRIPTION("LZ4 decompressor");
720#endif