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