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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