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		 * 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
721