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			LZ4_memcpy(op, ip, length);
267			ip += length;
268			op += length;
269
270			/* Necessarily EOF, due to parsing restrictions */
271			if (!partialDecoding || (cpy == oend))
272				break;
273		} else {
274			/* may overwrite up to WILDCOPYLENGTH beyond cpy */
275			LZ4_wildCopy(op, ip, cpy);
276			ip += length;
277			op = cpy;
278		}
 
 
 
279
280		/* get offset */
281		offset = LZ4_readLE16(ip);
282		ip += 2;
283		match = op - offset;
284
285		/* get matchlength */
286		length = token & ML_MASK;
287
288_copy_match:
289		if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) {
290			/* Error : offset outside buffers */
291			goto _output_error;
292		}
293
294		/* costs ~1%; silence an msan warning when offset == 0 */
295		/*
296		 * note : when partialDecoding, there is no guarantee that
297		 * at least 4 bytes remain available in output buffer
298		 */
299		if (!partialDecoding) {
300			assert(oend > op);
301			assert(oend - op >= 4);
302
303			LZ4_write32(op, (U32)offset);
304		}
305
 
 
306		if (length == ML_MASK) {
307			unsigned int s;
308
309			do {
310				s = *ip++;
311
312				if ((endOnInput) && (ip > iend - LASTLITERALS))
313					goto _output_error;
314
315				length += s;
316			} while (s == 255);
317
318			if ((safeDecode)
319				&& unlikely(
320					(uptrval)(op) + length < (uptrval)op)) {
321				/* overflow detection */
322				goto _output_error;
323			}
324		}
325
326		length += MINMATCH;
327
328		/* match starting within external dictionary */
329		if ((dict == usingExtDict) && (match < lowPrefix)) {
330			if (unlikely(op + length > oend - LASTLITERALS)) {
331				/* doesn't respect parsing restriction */
332				if (!partialDecoding)
333					goto _output_error;
334				length = min(length, (size_t)(oend - op));
335			}
336
337			if (length <= (size_t)(lowPrefix - match)) {
338				/*
339				 * match fits entirely within external
340				 * dictionary : just copy
341				 */
342				memmove(op, dictEnd - (lowPrefix - match),
343					length);
344				op += length;
345			} else {
346				/*
347				 * match stretches into both external
348				 * dictionary and current block
349				 */
350				size_t const copySize = (size_t)(lowPrefix - match);
351				size_t const restSize = length - copySize;
352
353				LZ4_memcpy(op, dictEnd - copySize, copySize);
354				op += copySize;
355				if (restSize > (size_t)(op - lowPrefix)) {
356					/* overlap copy */
357					BYTE * const endOfMatch = op + restSize;
358					const BYTE *copyFrom = lowPrefix;
359
360					while (op < endOfMatch)
361						*op++ = *copyFrom++;
362				} else {
363					LZ4_memcpy(op, lowPrefix, restSize);
364					op += restSize;
365				}
366			}
367			continue;
368		}
369
370		/* copy match within block */
371		cpy = op + length;
372
373		/*
374		 * partialDecoding :
375		 * may not respect endBlock parsing restrictions
376		 */
377		assert(op <= oend);
378		if (partialDecoding &&
379		    (cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
380			size_t const mlen = min(length, (size_t)(oend - op));
381			const BYTE * const matchEnd = match + mlen;
382			BYTE * const copyEnd = op + mlen;
383
384			if (matchEnd > op) {
385				/* overlap copy */
386				while (op < copyEnd)
387					*op++ = *match++;
388			} else {
389				LZ4_memcpy(op, match, mlen);
390			}
391			op = copyEnd;
392			if (op == oend)
393				break;
394			continue;
395		}
396
397		if (unlikely(offset < 8)) {
398			op[0] = match[0];
399			op[1] = match[1];
400			op[2] = match[2];
401			op[3] = match[3];
402			match += inc32table[offset];
403			LZ4_memcpy(op + 4, match, 4);
404			match -= dec64table[offset];
 
 
 
 
 
 
 
 
 
405		} else {
406			LZ4_copy8(op, match);
407			match += 8;
408		}
 
 
409
410		op += 8;
411
412		if (unlikely(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) {
413			BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
414
415			if (cpy > oend - LASTLITERALS) {
416				/*
417				 * Error : last LASTLITERALS bytes
418				 * must be literals (uncompressed)
419				 */
420				goto _output_error;
421			}
422
423			if (op < oCopyLimit) {
424				LZ4_wildCopy(op, match, oCopyLimit);
425				match += oCopyLimit - op;
426				op = oCopyLimit;
427			}
 
428			while (op < cpy)
429				*op++ = *match++;
430		} else {
431			LZ4_copy8(op, match);
432			if (length > 16)
433				LZ4_wildCopy(op + 8, match + 8, cpy);
 
 
 
 
434		}
435		op = cpy; /* wildcopy correction */
 
436	}
437
438	/* end of decoding */
439	if (endOnInput) {
440		/* Nb of output bytes decoded */
441		return (int) (((char *)op) - dst);
442	} else {
443		/* Nb of input bytes read */
444		return (int) (((const char *)ip) - src);
445	}
446
447	/* Overflow error detected */
448_output_error:
449	return (int) (-(((const char *)ip) - src)) - 1;
450}
451
452int LZ4_decompress_safe(const char *source, char *dest,
453	int compressedSize, int maxDecompressedSize)
454{
455	return LZ4_decompress_generic(source, dest,
456				      compressedSize, maxDecompressedSize,
457				      endOnInputSize, decode_full_block,
458				      noDict, (BYTE *)dest, NULL, 0);
459}
460
461int LZ4_decompress_safe_partial(const char *src, char *dst,
462	int compressedSize, int targetOutputSize, int dstCapacity)
463{
464	dstCapacity = min(targetOutputSize, dstCapacity);
465	return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity,
466				      endOnInputSize, partial_decode,
467				      noDict, (BYTE *)dst, NULL, 0);
468}
469
470int LZ4_decompress_fast(const char *source, char *dest, int originalSize)
 
471{
472	return LZ4_decompress_generic(source, dest, 0, originalSize,
473				      endOnOutputSize, decode_full_block,
474				      withPrefix64k,
475				      (BYTE *)dest - 64 * KB, NULL, 0);
476}
477
478/* ===== Instantiate a few more decoding cases, used more than once. ===== */
479
480int LZ4_decompress_safe_withPrefix64k(const char *source, char *dest,
481				      int compressedSize, int maxOutputSize)
482{
483	return LZ4_decompress_generic(source, dest,
484				      compressedSize, maxOutputSize,
485				      endOnInputSize, decode_full_block,
486				      withPrefix64k,
487				      (BYTE *)dest - 64 * KB, NULL, 0);
488}
489
490static int LZ4_decompress_safe_withSmallPrefix(const char *source, char *dest,
491					       int compressedSize,
492					       int maxOutputSize,
493					       size_t prefixSize)
494{
495	return LZ4_decompress_generic(source, dest,
496				      compressedSize, maxOutputSize,
497				      endOnInputSize, decode_full_block,
498				      noDict,
499				      (BYTE *)dest - prefixSize, NULL, 0);
500}
501
502int LZ4_decompress_safe_forceExtDict(const char *source, char *dest,
503				     int compressedSize, int maxOutputSize,
504				     const void *dictStart, size_t dictSize)
505{
506	return LZ4_decompress_generic(source, dest,
507				      compressedSize, maxOutputSize,
508				      endOnInputSize, decode_full_block,
509				      usingExtDict, (BYTE *)dest,
510				      (const BYTE *)dictStart, dictSize);
511}
512
513static int LZ4_decompress_fast_extDict(const char *source, char *dest,
514				       int originalSize,
515				       const void *dictStart, size_t dictSize)
516{
517	return LZ4_decompress_generic(source, dest,
518				      0, originalSize,
519				      endOnOutputSize, decode_full_block,
520				      usingExtDict, (BYTE *)dest,
521				      (const BYTE *)dictStart, dictSize);
522}
523
524/*
525 * The "double dictionary" mode, for use with e.g. ring buffers: the first part
526 * of the dictionary is passed as prefix, and the second via dictStart + dictSize.
527 * These routines are used only once, in LZ4_decompress_*_continue().
528 */
529static FORCE_INLINE
530int LZ4_decompress_safe_doubleDict(const char *source, char *dest,
531				   int compressedSize, int maxOutputSize,
532				   size_t prefixSize,
533				   const void *dictStart, size_t dictSize)
534{
535	return LZ4_decompress_generic(source, dest,
536				      compressedSize, maxOutputSize,
537				      endOnInputSize, decode_full_block,
538				      usingExtDict, (BYTE *)dest - prefixSize,
539				      (const BYTE *)dictStart, dictSize);
540}
541
542static FORCE_INLINE
543int LZ4_decompress_fast_doubleDict(const char *source, char *dest,
544				   int originalSize, size_t prefixSize,
545				   const void *dictStart, size_t dictSize)
546{
547	return LZ4_decompress_generic(source, dest,
548				      0, originalSize,
549				      endOnOutputSize, decode_full_block,
550				      usingExtDict, (BYTE *)dest - prefixSize,
551				      (const BYTE *)dictStart, dictSize);
552}
553
554/* ===== streaming decompression functions ===== */
 
 
 
 
 
 
 
 
 
 
 
 
555
556int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
557	const char *dictionary, int dictSize)
558{
559	LZ4_streamDecode_t_internal *lz4sd =
560		&LZ4_streamDecode->internal_donotuse;
 
 
 
 
561
562	lz4sd->prefixSize = (size_t) dictSize;
563	lz4sd->prefixEnd = (const BYTE *) dictionary + dictSize;
564	lz4sd->externalDict = NULL;
565	lz4sd->extDictSize	= 0;
566	return 1;
567}
 
 
 
 
 
 
 
568
569/*
570 * *_continue() :
571 * These decoding functions allow decompression of multiple blocks
572 * in "streaming" mode.
573 * Previously decoded blocks must still be available at the memory
574 * position where they were decoded.
575 * If it's not possible, save the relevant part of
576 * decoded data into a safe buffer,
577 * and indicate where it stands using LZ4_setStreamDecode()
578 */
579int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
580	const char *source, char *dest, int compressedSize, int maxOutputSize)
581{
582	LZ4_streamDecode_t_internal *lz4sd =
583		&LZ4_streamDecode->internal_donotuse;
584	int result;
585
586	if (lz4sd->prefixSize == 0) {
587		/* The first call, no dictionary yet. */
588		assert(lz4sd->extDictSize == 0);
589		result = LZ4_decompress_safe(source, dest,
590			compressedSize, maxOutputSize);
591		if (result <= 0)
592			return result;
593		lz4sd->prefixSize = result;
594		lz4sd->prefixEnd = (BYTE *)dest + result;
595	} else if (lz4sd->prefixEnd == (BYTE *)dest) {
596		/* They're rolling the current segment. */
597		if (lz4sd->prefixSize >= 64 * KB - 1)
598			result = LZ4_decompress_safe_withPrefix64k(source, dest,
599				compressedSize, maxOutputSize);
600		else if (lz4sd->extDictSize == 0)
601			result = LZ4_decompress_safe_withSmallPrefix(source,
602				dest, compressedSize, maxOutputSize,
603				lz4sd->prefixSize);
604		else
605			result = LZ4_decompress_safe_doubleDict(source, dest,
606				compressedSize, maxOutputSize,
607				lz4sd->prefixSize,
608				lz4sd->externalDict, lz4sd->extDictSize);
609		if (result <= 0)
610			return result;
611		lz4sd->prefixSize += result;
612		lz4sd->prefixEnd  += result;
613	} else {
614		/*
615		 * The buffer wraps around, or they're
616		 * switching to another buffer.
617		 */
618		lz4sd->extDictSize = lz4sd->prefixSize;
619		lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
620		result = LZ4_decompress_safe_forceExtDict(source, dest,
621			compressedSize, maxOutputSize,
622			lz4sd->externalDict, lz4sd->extDictSize);
623		if (result <= 0)
624			return result;
625		lz4sd->prefixSize = result;
626		lz4sd->prefixEnd  = (BYTE *)dest + result;
627	}
 
 
628
629	return result;
 
 
630}
631
632int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
633	const char *source, char *dest, int originalSize)
634{
635	LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
636	int result;
637
638	if (lz4sd->prefixSize == 0) {
639		assert(lz4sd->extDictSize == 0);
640		result = LZ4_decompress_fast(source, dest, originalSize);
641		if (result <= 0)
642			return result;
643		lz4sd->prefixSize = originalSize;
644		lz4sd->prefixEnd = (BYTE *)dest + originalSize;
645	} else if (lz4sd->prefixEnd == (BYTE *)dest) {
646		if (lz4sd->prefixSize >= 64 * KB - 1 ||
647		    lz4sd->extDictSize == 0)
648			result = LZ4_decompress_fast(source, dest,
649						     originalSize);
650		else
651			result = LZ4_decompress_fast_doubleDict(source, dest,
652				originalSize, lz4sd->prefixSize,
653				lz4sd->externalDict, lz4sd->extDictSize);
654		if (result <= 0)
655			return result;
656		lz4sd->prefixSize += originalSize;
657		lz4sd->prefixEnd  += originalSize;
658	} else {
659		lz4sd->extDictSize = lz4sd->prefixSize;
660		lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
661		result = LZ4_decompress_fast_extDict(source, dest,
662			originalSize, lz4sd->externalDict, lz4sd->extDictSize);
663		if (result <= 0)
664			return result;
665		lz4sd->prefixSize = originalSize;
666		lz4sd->prefixEnd = (BYTE *)dest + originalSize;
667	}
668	return result;
669}
670
671int LZ4_decompress_safe_usingDict(const char *source, char *dest,
672				  int compressedSize, int maxOutputSize,
673				  const char *dictStart, int dictSize)
674{
675	if (dictSize == 0)
676		return LZ4_decompress_safe(source, dest,
677					   compressedSize, maxOutputSize);
678	if (dictStart+dictSize == dest) {
679		if (dictSize >= 64 * KB - 1)
680			return LZ4_decompress_safe_withPrefix64k(source, dest,
681				compressedSize, maxOutputSize);
682		return LZ4_decompress_safe_withSmallPrefix(source, dest,
683			compressedSize, maxOutputSize, dictSize);
684	}
685	return LZ4_decompress_safe_forceExtDict(source, dest,
686		compressedSize, maxOutputSize, dictStart, dictSize);
687}
 
 
 
688
689int LZ4_decompress_fast_usingDict(const char *source, char *dest,
690				  int originalSize,
691				  const char *dictStart, int dictSize)
692{
693	if (dictSize == 0 || dictStart + dictSize == dest)
694		return LZ4_decompress_fast(source, dest, originalSize);
695
696	return LZ4_decompress_fast_extDict(source, dest, originalSize,
697		dictStart, dictSize);
 
 
 
 
 
 
 
698}
699
700#ifndef STATIC
701EXPORT_SYMBOL(LZ4_decompress_safe);
702EXPORT_SYMBOL(LZ4_decompress_safe_partial);
703EXPORT_SYMBOL(LZ4_decompress_fast);
704EXPORT_SYMBOL(LZ4_setStreamDecode);
705EXPORT_SYMBOL(LZ4_decompress_safe_continue);
706EXPORT_SYMBOL(LZ4_decompress_fast_continue);
707EXPORT_SYMBOL(LZ4_decompress_safe_usingDict);
708EXPORT_SYMBOL(LZ4_decompress_fast_usingDict);
709
710MODULE_LICENSE("Dual BSD/GPL");
711MODULE_DESCRIPTION("LZ4 decompressor");
712#endif