2 * LZ4 - Fast LZ compression algorithm
4 * Copyright (C) 2011-2013, Yann Collet.
5 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are
11 * * Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * * Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following disclaimer
15 * in the documentation and/or other materials provided with the
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 * You can contact the author at :
31 * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
32 * - LZ4 source repository : http://code.google.com/p/lz4/
35 #include <sys/zfs_context.h>
37 static int real_LZ4_compress(const char *source, char *dest, int isize,
39 static int LZ4_compressBound(int isize);
40 static int LZ4_uncompress_unknownOutputSize(const char *source, char *dest,
41 int isize, int maxOutputSize);
42 static int LZ4_compressCtx(void *ctx, const char *source, char *dest,
43 int isize, int osize);
44 static int LZ4_compress64kCtx(void *ctx, const char *source, char *dest,
45 int isize, int osize);
47 static kmem_cache_t *lz4_ctx_cache;
51 lz4_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
56 ASSERT(d_len >= sizeof (bufsiz));
58 bufsiz = real_LZ4_compress(s_start, &dest[sizeof (bufsiz)], s_len,
59 d_len - sizeof (bufsiz));
61 /* Signal an error if the compression routine returned zero. */
66 * Encode the compresed buffer size at the start. We'll need this in
67 * decompression to counter the effects of padding which might be
68 * added to the compressed buffer and which, if unhandled, would
69 * confuse the hell out of our decompression function.
71 *(uint32_t *)dest = BE_32(bufsiz);
73 return (bufsiz + sizeof (bufsiz));
78 lz4_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
80 const char *src = s_start;
81 uint32_t bufsiz = BE_IN32(src);
83 /* invalid compressed buffer size encoded at start */
84 if (bufsiz + sizeof (bufsiz) > s_len)
88 * Returns 0 on success (decompression function returned non-negative)
89 * and non-zero on failure (decompression function returned negative.
91 return (LZ4_uncompress_unknownOutputSize(&src[sizeof (bufsiz)],
92 d_start, bufsiz, d_len) < 0);
96 * LZ4 API Description:
99 * real_LZ4_compress() :
100 * isize : is the input size. Max supported value is ~1.9GB
101 * return : the number of bytes written in buffer dest
102 * or 0 if the compression fails (if LZ4_COMPRESSMIN is set).
103 * note : destination buffer must be already allocated.
104 * destination buffer must be sized to handle worst cases
105 * situations (input data not compressible) worst case size
106 * evaluation is provided by function LZ4_compressBound().
110 * LZ4_compressBound() :
111 * Provides the maximum size that LZ4 may output in a "worst case"
112 * scenario (input data not compressible) primarily useful for memory
113 * allocation of output buffer.
115 * isize : is the input size. Max supported value is ~1.9GB
116 * return : maximum output size in a "worst case" scenario
117 * note : this function is limited by "int" range (2^31-1)
119 * LZ4_uncompress_unknownOutputSize() :
120 * isize : is the input size, therefore the compressed size
121 * maxOutputSize : is the size of the destination buffer (which must be
123 * return : the number of bytes decoded in the destination buffer
124 * (necessarily <= maxOutputSize). If the source stream is
125 * malformed, the function will stop decoding and return a
126 * negative result, indicating the byte position of the faulty
127 * instruction. This function never writes beyond dest +
128 * maxOutputSize, and is therefore protected against malicious
130 * note : Destination buffer must be already allocated.
132 * LZ4_compressCtx() :
133 * This function explicitly handles the CTX memory structure.
135 * ILLUMOS CHANGES: the CTX memory structure must be explicitly allocated
136 * by the caller (either on the stack or using kmem_zalloc). Passing NULL
139 * LZ4_compress64kCtx() :
140 * Same as LZ4_compressCtx(), but specific to small inputs (<64KB).
141 * isize *Must* be <64KB, otherwise the output will be corrupted.
143 * ILLUMOS CHANGES: the CTX memory structure must be explicitly allocated
144 * by the caller (either on the stack or using kmem_zalloc). Passing NULL
153 * COMPRESSIONLEVEL: Increasing this value improves compression ratio
154 * Lowering this value reduces memory usage. Reduced memory usage
155 * typically improves speed, due to cache effect (ex: L1 32KB for Intel,
156 * L1 64KB for AMD). Memory usage formula : N->2^(N+2) Bytes
157 * (examples : 12 -> 16KB ; 17 -> 512KB)
159 #define COMPRESSIONLEVEL 12
162 * NOTCOMPRESSIBLE_CONFIRMATION: Decreasing this value will make the
163 * algorithm skip faster data segments considered "incompressible".
164 * This may decrease compression ratio dramatically, but will be
165 * faster on incompressible data. Increasing this value will make
166 * the algorithm search more before declaring a segment "incompressible".
167 * This could improve compression a bit, but will be slower on
168 * incompressible data. The default value (6) is recommended.
170 #define NOTCOMPRESSIBLE_CONFIRMATION 6
173 * BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE: This will provide a boost to
174 * performance for big endian cpu, but the resulting compressed stream
175 * will be incompatible with little-endian CPU. You can set this option
176 * to 1 in situations where data will stay within closed environment.
177 * This option is useless on Little_Endian CPU (such as x86).
179 /* #define BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE 1 */
182 * CPU Feature Detection
185 /* 32 or 64 bits ? */
186 #if (defined(__x86_64__) || defined(__x86_64) || defined(__amd64__) || \
187 defined(__amd64) || defined(__ppc64__) || defined(_WIN64) || \
188 defined(__LP64__) || defined(_LP64))
191 * Illumos: On amd64 we have 20k of stack and 24k on sun4u and sun4v, so we
192 * can spend 16k on the algorithm
194 /* FreeBSD: Use heap for all platforms for now */
199 * Illumos: On i386 we only have 12k of stack, so in order to maintain the
200 * same COMPRESSIONLEVEL we have to use heap allocation. Performance will
201 * suck, but alas, it's ZFS on 32-bit we're talking about, so...
207 * Little Endian or Big Endian?
208 * Note: overwrite the below #define if you know your architecture endianess.
210 #if BYTE_ORDER == BIG_ENDIAN
211 #define LZ4_BIG_ENDIAN 1
214 * Little Endian assumed. PDP Endian and other very rare endian format
220 * Unaligned memory access is automatically enabled for "common" CPU,
221 * such as x86. For others CPU, the compiler will be more cautious, and
222 * insert extra code to ensure aligned access is respected. If you know
223 * your target CPU supports unaligned memory access, you may want to
224 * force this option manually to improve performance
226 #if defined(__ARM_FEATURE_UNALIGNED)
227 #define LZ4_FORCE_UNALIGNED_ACCESS 1
231 * FreeBSD: can't use GCC's __builtin_ctz when using sparc64 because
232 * gcc currently rely on libcompiler_rt.
234 * TODO: revisit this when situation changes.
236 #if defined(__sparc64__)
237 #define LZ4_FORCE_SW_BITCOUNT
243 #if __STDC_VERSION__ >= 199901L /* C99 */
244 /* "restrict" is a known keyword */
246 /* Disable restrict */
250 #define lz4_bswap16(x) ((unsigned short int) ((((x) >> 8) & 0xffu) | \
251 (((x) & 0xffu) << 8)))
253 #define expect(expr, value) (__builtin_expect((expr), (value)))
258 #if defined(unlikely)
262 #define likely(expr) expect((expr) != 0, 1)
263 #define unlikely(expr) expect((expr) != 0, 0)
272 #ifndef LZ4_FORCE_UNALIGNED_ACCESS
276 typedef struct _U16_S {
279 typedef struct _U32_S {
282 typedef struct _U64_S {
286 #ifndef LZ4_FORCE_UNALIGNED_ACCESS
290 #define A64(x) (((U64_S *)(x))->v)
291 #define A32(x) (((U32_S *)(x))->v)
292 #define A16(x) (((U16_S *)(x))->v)
299 #define HASH_LOG COMPRESSIONLEVEL
300 #define HASHTABLESIZE (1 << HASH_LOG)
301 #define HASH_MASK (HASHTABLESIZE - 1)
303 #define SKIPSTRENGTH (NOTCOMPRESSIBLE_CONFIRMATION > 2 ? \
304 NOTCOMPRESSIBLE_CONFIRMATION : 2)
307 * Defines if memory is allocated into the stack (local variable),
308 * or into the heap (kmem_alloc()).
310 #define HEAPMODE (HASH_LOG > STACKLIMIT)
312 #define LASTLITERALS 5
313 #define MFLIMIT (COPYLENGTH + MINMATCH)
314 #define MINLENGTH (MFLIMIT + 1)
317 #define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
320 #define ML_MASK ((1U<<ML_BITS)-1)
321 #define RUN_BITS (8-ML_BITS)
322 #define RUN_MASK ((1U<<RUN_BITS)-1)
326 * Architecture-specific macros
332 #define LZ4_COPYSTEP(s, d) A64(d) = A64(s); d += 8; s += 8;
333 #define LZ4_COPYPACKET(s, d) LZ4_COPYSTEP(s, d)
334 #define LZ4_SECURECOPY(s, d, e) if (d < e) LZ4_WILDCOPY(s, d, e)
336 #define INITBASE(base) const BYTE* const base = ip
337 #else /* !LZ4_ARCH64 */
341 #define LZ4_COPYSTEP(s, d) A32(d) = A32(s); d += 4; s += 4;
342 #define LZ4_COPYPACKET(s, d) LZ4_COPYSTEP(s, d); LZ4_COPYSTEP(s, d);
343 #define LZ4_SECURECOPY LZ4_WILDCOPY
344 #define HTYPE const BYTE *
345 #define INITBASE(base) const int base = 0
346 #endif /* !LZ4_ARCH64 */
348 #if (defined(LZ4_BIG_ENDIAN) && !defined(BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE))
349 #define LZ4_READ_LITTLEENDIAN_16(d, s, p) \
350 { U16 v = A16(p); v = lz4_bswap16(v); d = (s) - v; }
351 #define LZ4_WRITE_LITTLEENDIAN_16(p, i) \
352 { U16 v = (U16)(i); v = lz4_bswap16(v); A16(p) = v; p += 2; }
354 #define LZ4_READ_LITTLEENDIAN_16(d, s, p) { d = (s) - A16(p); }
355 #define LZ4_WRITE_LITTLEENDIAN_16(p, v) { A16(p) = v; p += 2; }
359 /* Local structures */
361 HTYPE hashTable[HASHTABLESIZE];
366 #define LZ4_HASH_FUNCTION(i) (((i) * 2654435761U) >> ((MINMATCH * 8) - \
368 #define LZ4_HASH_VALUE(p) LZ4_HASH_FUNCTION(A32(p))
369 #define LZ4_WILDCOPY(s, d, e) do { LZ4_COPYPACKET(s, d) } while (d < e);
370 #define LZ4_BLINDCOPY(s, d, l) { BYTE* e = (d) + l; LZ4_WILDCOPY(s, d, e); \
374 /* Private functions */
378 LZ4_NbCommonBytes(register U64 val)
380 #if defined(LZ4_BIG_ENDIAN)
381 #if !defined(LZ4_FORCE_SW_BITCOUNT)
382 return (__builtin_clzll(val) >> 3);
401 #if !defined(LZ4_FORCE_SW_BITCOUNT)
402 return (__builtin_ctzll(val) >> 3);
404 static const int DeBruijnBytePos[64] =
405 { 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5,
406 3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5,
407 5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4,
408 4, 5, 7, 2, 6, 5, 7, 6, 7, 7
410 return DeBruijnBytePos[((U64) ((val & -val) * 0x0218A392CDABBD3F)) >>
419 LZ4_NbCommonBytes(register U32 val)
421 #if defined(LZ4_BIG_ENDIAN)
422 #if !defined(LZ4_FORCE_SW_BITCOUNT)
423 return (__builtin_clz(val) >> 3);
437 #if !defined(LZ4_FORCE_SW_BITCOUNT)
438 return (__builtin_ctz(val) >> 3);
440 static const int DeBruijnBytePos[32] = {
441 0, 0, 3, 0, 3, 1, 3, 0,
442 3, 2, 2, 1, 3, 2, 0, 1,
443 3, 3, 1, 2, 2, 2, 2, 0,
444 3, 1, 2, 0, 1, 0, 1, 1
446 return DeBruijnBytePos[((U32) ((val & -(S32) val) * 0x077CB531U)) >>
454 /* Public functions */
457 LZ4_compressBound(int isize)
459 return (isize + (isize / 255) + 16);
462 /* Compression functions */
466 LZ4_compressCtx(void *ctx, const char *source, char *dest, int isize,
470 struct refTables *srt = (struct refTables *)ctx;
471 HTYPE *HashTable = (HTYPE *) (srt->hashTable);
473 HTYPE HashTable[HASHTABLESIZE] = { 0 };
476 const BYTE *ip = (BYTE *) source;
478 const BYTE *anchor = ip;
479 const BYTE *const iend = ip + isize;
480 const BYTE *const oend = (BYTE *) dest + osize;
481 const BYTE *const mflimit = iend - MFLIMIT;
482 #define matchlimit (iend - LASTLITERALS)
484 BYTE *op = (BYTE *) dest;
487 const int skipStrength = SKIPSTRENGTH;
492 if (isize < MINLENGTH)
496 HashTable[LZ4_HASH_VALUE(ip)] = ip - base;
498 forwardH = LZ4_HASH_VALUE(ip);
502 int findMatchAttempts = (1U << skipStrength) + 3;
503 const BYTE *forwardIp = ip;
510 int step = findMatchAttempts++ >> skipStrength;
512 forwardIp = ip + step;
514 if unlikely(forwardIp > mflimit) {
518 forwardH = LZ4_HASH_VALUE(forwardIp);
519 ref = base + HashTable[h];
520 HashTable[h] = ip - base;
522 } while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));
525 while ((ip > anchor) && (ref > (BYTE *) source) &&
526 unlikely(ip[-1] == ref[-1])) {
531 /* Encode Literal length */
532 length = ip - anchor;
535 /* Check output limit */
536 if unlikely(op + length + (2 + 1 + LASTLITERALS) +
537 (length >> 8) > oend)
540 if (length >= (int)RUN_MASK) {
541 *token = (RUN_MASK << ML_BITS);
542 len = length - RUN_MASK;
543 for (; len > 254; len -= 255)
547 *token = (length << ML_BITS);
550 LZ4_BLINDCOPY(anchor, op, length);
554 LZ4_WRITE_LITTLEENDIAN_16(op, ip - ref);
558 ref += MINMATCH; /* MinMatch verified */
560 while likely(ip < matchlimit - (STEPSIZE - 1)) {
561 UARCH diff = AARCH(ref) ^ AARCH(ip);
567 ip += LZ4_NbCommonBytes(diff);
571 if ((ip < (matchlimit - 3)) && (A32(ref) == A32(ip))) {
576 if ((ip < (matchlimit - 1)) && (A16(ref) == A16(ip))) {
580 if ((ip < matchlimit) && (*ref == *ip))
584 /* Encode MatchLength */
586 /* Check output limit */
587 if unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend)
589 if (len >= (int)ML_MASK) {
592 for (; len > 509; len -= 510) {
604 /* Test end of chunk */
610 HashTable[LZ4_HASH_VALUE(ip - 2)] = ip - 2 - base;
612 /* Test next position */
613 ref = base + HashTable[LZ4_HASH_VALUE(ip)];
614 HashTable[LZ4_HASH_VALUE(ip)] = ip - base;
615 if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) {
620 /* Prepare next loop */
622 forwardH = LZ4_HASH_VALUE(ip);
626 /* Encode Last Literals */
628 int lastRun = iend - anchor;
629 if (op + lastRun + 1 + ((lastRun + 255 - RUN_MASK) / 255) >
632 if (lastRun >= (int)RUN_MASK) {
633 *op++ = (RUN_MASK << ML_BITS);
635 for (; lastRun > 254; lastRun -= 255) {
638 *op++ = (BYTE)lastRun;
640 *op++ = (lastRun << ML_BITS);
641 (void) memcpy(op, anchor, iend - anchor);
646 return (int)(((char *)op) - dest);
651 /* Note : this function is valid only if isize < LZ4_64KLIMIT */
652 #define LZ4_64KLIMIT ((1 << 16) + (MFLIMIT - 1))
653 #define HASHLOG64K (HASH_LOG + 1)
654 #define HASH64KTABLESIZE (1U << HASHLOG64K)
655 #define LZ4_HASH64K_FUNCTION(i) (((i) * 2654435761U) >> ((MINMATCH*8) - \
657 #define LZ4_HASH64K_VALUE(p) LZ4_HASH64K_FUNCTION(A32(p))
661 LZ4_compress64kCtx(void *ctx, const char *source, char *dest, int isize,
665 struct refTables *srt = (struct refTables *)ctx;
666 U16 *HashTable = (U16 *) (srt->hashTable);
668 U16 HashTable[HASH64KTABLESIZE] = { 0 };
671 const BYTE *ip = (BYTE *) source;
672 const BYTE *anchor = ip;
673 const BYTE *const base = ip;
674 const BYTE *const iend = ip + isize;
675 const BYTE *const oend = (BYTE *) dest + osize;
676 const BYTE *const mflimit = iend - MFLIMIT;
677 #define matchlimit (iend - LASTLITERALS)
679 BYTE *op = (BYTE *) dest;
682 const int skipStrength = SKIPSTRENGTH;
686 if (isize < MINLENGTH)
691 forwardH = LZ4_HASH64K_VALUE(ip);
695 int findMatchAttempts = (1U << skipStrength) + 3;
696 const BYTE *forwardIp = ip;
703 int step = findMatchAttempts++ >> skipStrength;
705 forwardIp = ip + step;
707 if (forwardIp > mflimit) {
711 forwardH = LZ4_HASH64K_VALUE(forwardIp);
712 ref = base + HashTable[h];
713 HashTable[h] = ip - base;
715 } while (A32(ref) != A32(ip));
718 while ((ip > anchor) && (ref > (BYTE *) source) &&
719 (ip[-1] == ref[-1])) {
724 /* Encode Literal length */
725 length = ip - anchor;
728 /* Check output limit */
729 if unlikely(op + length + (2 + 1 + LASTLITERALS) +
730 (length >> 8) > oend)
733 if (length >= (int)RUN_MASK) {
734 *token = (RUN_MASK << ML_BITS);
735 len = length - RUN_MASK;
736 for (; len > 254; len -= 255)
740 *token = (length << ML_BITS);
743 LZ4_BLINDCOPY(anchor, op, length);
747 LZ4_WRITE_LITTLEENDIAN_16(op, ip - ref);
751 ref += MINMATCH; /* MinMatch verified */
753 while (ip < matchlimit - (STEPSIZE - 1)) {
754 UARCH diff = AARCH(ref) ^ AARCH(ip);
760 ip += LZ4_NbCommonBytes(diff);
764 if ((ip < (matchlimit - 3)) && (A32(ref) == A32(ip))) {
769 if ((ip < (matchlimit - 1)) && (A16(ref) == A16(ip))) {
773 if ((ip < matchlimit) && (*ref == *ip))
777 /* Encode MatchLength */
779 /* Check output limit */
780 if unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend)
782 if (len >= (int)ML_MASK) {
785 for (; len > 509; len -= 510) {
797 /* Test end of chunk */
803 HashTable[LZ4_HASH64K_VALUE(ip - 2)] = ip - 2 - base;
805 /* Test next position */
806 ref = base + HashTable[LZ4_HASH64K_VALUE(ip)];
807 HashTable[LZ4_HASH64K_VALUE(ip)] = ip - base;
808 if (A32(ref) == A32(ip)) {
813 /* Prepare next loop */
815 forwardH = LZ4_HASH64K_VALUE(ip);
819 /* Encode Last Literals */
821 int lastRun = iend - anchor;
822 if (op + lastRun + 1 + ((lastRun + 255 - RUN_MASK) / 255) >
825 if (lastRun >= (int)RUN_MASK) {
826 *op++ = (RUN_MASK << ML_BITS);
828 for (; lastRun > 254; lastRun -= 255)
830 *op++ = (BYTE)lastRun;
832 *op++ = (lastRun << ML_BITS);
833 (void) memcpy(op, anchor, iend - anchor);
838 return (int)(((char *)op) - dest);
842 real_LZ4_compress(const char *source, char *dest, int isize, int osize)
845 void *ctx = kmem_cache_alloc(lz4_ctx_cache, KM_NOSLEEP);
849 * out of kernel memory, gently fall through - this will disable
850 * compression in zio_compress_data
855 bzero(ctx, sizeof(struct refTables));
856 if (isize < LZ4_64KLIMIT)
857 result = LZ4_compress64kCtx(ctx, source, dest, isize, osize);
859 result = LZ4_compressCtx(ctx, source, dest, isize, osize);
861 kmem_cache_free(lz4_ctx_cache, ctx);
864 if (isize < (int)LZ4_64KLIMIT)
865 return (LZ4_compress64kCtx(NULL, source, dest, isize, osize));
866 return (LZ4_compressCtx(NULL, source, dest, isize, osize));
870 /* Decompression functions */
873 * Note: The decoding functionLZ4_uncompress_unknownOutputSize() is safe
874 * against "buffer overflow" attack type. They will never write nor
875 * read outside of the provided output buffers.
876 * LZ4_uncompress_unknownOutputSize() also insures that it will never
877 * read outside of the input buffer. A corrupted input will produce
878 * an error result, a negative int, indicating the position of the
879 * error within input stream.
883 LZ4_uncompress_unknownOutputSize(const char *source, char *dest, int isize,
886 /* Local Variables */
887 const BYTE *restrict ip = (const BYTE *) source;
888 const BYTE *const iend = ip + isize;
891 BYTE *op = (BYTE *) dest;
892 BYTE *const oend = op + maxOutputSize;
895 size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
897 size_t dec64table[] = {0, 0, 0, (size_t)-1, 0, 1, 2, 3};
907 if ((length = (token >> ML_BITS)) == RUN_MASK) {
909 while ((ip < iend) && (s == 255)) {
916 if ((cpy > oend - COPYLENGTH) ||
917 (ip + length > iend - COPYLENGTH)) {
919 /* Error: writes beyond output buffer */
921 if (ip + length != iend)
923 * Error: LZ4 format requires to consume all
924 * input at this stage
927 (void) memcpy(op, ip, length);
929 /* Necessarily EOF, due to parsing restrictions */
932 LZ4_WILDCOPY(ip, op, cpy);
937 LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
939 if (ref < (BYTE * const) dest)
941 * Error: offset creates reference outside of
946 /* get matchlength */
947 if ((length = (token & ML_MASK)) == ML_MASK) {
956 /* copy repeated sequence */
957 if unlikely(op - ref < STEPSIZE) {
959 size_t dec64 = dec64table[op-ref];
969 ref -= dec32table[op-ref];
974 LZ4_COPYSTEP(ref, op);
976 cpy = op + length - (STEPSIZE - 4);
977 if (cpy > oend - COPYLENGTH) {
980 * Error: request to write outside of
984 LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
990 * Check EOF (should never happen, since
991 * last 5 bytes are supposed to be literals)
996 LZ4_SECURECOPY(ref, op, cpy);
997 op = cpy; /* correction */
1000 /* end of decoding */
1001 return (int)(((char *)op) - dest);
1003 /* write overflow error detected */
1005 return (int)(-(((char *)ip) - source));
1013 lz4_ctx_cache = kmem_cache_create("lz4_ctx", sizeof(struct refTables),
1014 0, NULL, NULL, NULL, NULL, NULL, 0);
1023 kmem_cache_destroy(lz4_ctx_cache);