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Diffstat (limited to '')
| -rw-r--r-- | lib/lz4/lz4_decompress.c | 720 |
1 files changed, 720 insertions, 0 deletions
diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c new file mode 100644 index 000000000..5b6705c4b --- /dev/null +++ b/lib/lz4/lz4_decompress.c @@ -0,0 +1,720 @@ +/* + * LZ4 - Fast LZ compression algorithm + * Copyright (C) 2011 - 2016, Yann Collet. + * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php) + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * You can contact the author at : + * - LZ4 homepage : http://www.lz4.org + * - LZ4 source repository : https://github.com/lz4/lz4 + * + * Changed for kernel usage by: + * Sven Schmidt <4sschmid@informatik.uni-hamburg.de> + */ + +/*-************************************ + * Dependencies + **************************************/ +#include <linux/lz4.h> +#include "lz4defs.h" +#include <linux/init.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <asm/unaligned.h> + +/*-***************************** + * Decompression functions + *******************************/ + +#define DEBUGLOG(l, ...) {} /* disabled */ + +#ifndef assert +#define assert(condition) ((void)0) +#endif + +/* + * LZ4_decompress_generic() : + * This generic decompression function covers all use cases. + * It shall be instantiated several times, using different sets of directives. + * Note that it is important for performance that this function really get inlined, + * in order to remove useless branches during compilation optimization. + */ +static FORCE_INLINE int LZ4_decompress_generic( + const char * const src, + char * const dst, + int srcSize, + /* + * If endOnInput == endOnInputSize, + * this value is `dstCapacity` + */ + int outputSize, + /* endOnOutputSize, endOnInputSize */ + endCondition_directive endOnInput, + /* full, partial */ + earlyEnd_directive partialDecoding, + /* noDict, withPrefix64k, usingExtDict */ + dict_directive dict, + /* always <= dst, == dst when no prefix */ + const BYTE * const lowPrefix, + /* only if dict == usingExtDict */ + const BYTE * const dictStart, + /* note : = 0 if noDict */ + const size_t dictSize + ) +{ + const BYTE *ip = (const BYTE *) src; + const BYTE * const iend = ip + srcSize; + + BYTE *op = (BYTE *) dst; + BYTE * const oend = op + outputSize; + BYTE *cpy; + + const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize; + static const unsigned int inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4}; + static const int dec64table[8] = {0, 0, 0, -1, -4, 1, 2, 3}; + + const int safeDecode = (endOnInput == endOnInputSize); + const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB))); + + /* Set up the "end" pointers for the shortcut. */ + const BYTE *const shortiend = iend - + (endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/; + const BYTE *const shortoend = oend - + (endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/; + + DEBUGLOG(5, "%s (srcSize:%i, dstSize:%i)", __func__, + srcSize, outputSize); + + /* Special cases */ + assert(lowPrefix <= op); + assert(src != NULL); + + /* Empty output buffer */ + if ((endOnInput) && (unlikely(outputSize == 0))) + return ((srcSize == 1) && (*ip == 0)) ? 0 : -1; + + if ((!endOnInput) && (unlikely(outputSize == 0))) + return (*ip == 0 ? 1 : -1); + + if ((endOnInput) && unlikely(srcSize == 0)) + return -1; + + /* Main Loop : decode sequences */ + while (1) { + size_t length; + const BYTE *match; + size_t offset; + + /* get literal length */ + unsigned int const token = *ip++; + length = token>>ML_BITS; + + /* ip < iend before the increment */ + assert(!endOnInput || ip <= iend); + + /* + * A two-stage shortcut for the most common case: + * 1) If the literal length is 0..14, and there is enough + * space, enter the shortcut and copy 16 bytes on behalf + * of the literals (in the fast mode, only 8 bytes can be + * safely copied this way). + * 2) Further if the match length is 4..18, copy 18 bytes + * in a similar manner; but we ensure that there's enough + * space in the output for those 18 bytes earlier, upon + * entering the shortcut (in other words, there is a + * combined check for both stages). + * + * The & in the likely() below is intentionally not && so that + * some compilers can produce better parallelized runtime code + */ + if ((endOnInput ? length != RUN_MASK : length <= 8) + /* + * strictly "less than" on input, to re-enter + * the loop with at least one byte + */ + && likely((endOnInput ? ip < shortiend : 1) & + (op <= shortoend))) { + /* Copy the literals */ + LZ4_memcpy(op, ip, endOnInput ? 16 : 8); + op += length; ip += length; + + /* + * The second stage: + * prepare for match copying, decode full info. + * If it doesn't work out, the info won't be wasted. + */ + length = token & ML_MASK; /* match length */ + offset = LZ4_readLE16(ip); + ip += 2; + match = op - offset; + assert(match <= op); /* check overflow */ + + /* Do not deal with overlapping matches. */ + if ((length != ML_MASK) && + (offset >= 8) && + (dict == withPrefix64k || match >= lowPrefix)) { + /* Copy the match. */ + LZ4_memcpy(op + 0, match + 0, 8); + LZ4_memcpy(op + 8, match + 8, 8); + LZ4_memcpy(op + 16, match + 16, 2); + op += length + MINMATCH; + /* Both stages worked, load the next token. */ + continue; + } + + /* + * The second stage didn't work out, but the info + * is ready. Propel it right to the point of match + * copying. + */ + goto _copy_match; + } + + /* decode literal length */ + if (length == RUN_MASK) { + unsigned int s; + + if (unlikely(endOnInput ? ip >= iend - RUN_MASK : 0)) { + /* overflow detection */ + goto _output_error; + } + do { + s = *ip++; + length += s; + } while (likely(endOnInput + ? ip < iend - RUN_MASK + : 1) & (s == 255)); + + if ((safeDecode) + && unlikely((uptrval)(op) + + length < (uptrval)(op))) { + /* overflow detection */ + goto _output_error; + } + if ((safeDecode) + && unlikely((uptrval)(ip) + + length < (uptrval)(ip))) { + /* overflow detection */ + goto _output_error; + } + } + + /* copy literals */ + cpy = op + length; + LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH); + + if (((endOnInput) && ((cpy > oend - MFLIMIT) + || (ip + length > iend - (2 + 1 + LASTLITERALS)))) + || ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) { + if (partialDecoding) { + if (cpy > oend) { + /* + * Partial decoding : + * stop in the middle of literal segment + */ + cpy = oend; + length = oend - op; + } + if ((endOnInput) + && (ip + length > iend)) { + /* + * Error : + * read attempt beyond + * end of input buffer + */ + goto _output_error; + } + } else { + if ((!endOnInput) + && (cpy != oend)) { + /* + * Error : + * block decoding must + * stop exactly there + */ + goto _output_error; + } + if ((endOnInput) + && ((ip + length != iend) + || (cpy > oend))) { + /* + * Error : + * input must be consumed + */ + goto _output_error; + } + } + + /* + * supports overlapping memory regions; only matters + * for in-place decompression scenarios + */ + LZ4_memmove(op, ip, length); + ip += length; + op += length; + + /* Necessarily EOF when !partialDecoding. + * When partialDecoding, it is EOF if we've either + * filled the output buffer or + * can't proceed with reading an offset for following match. + */ + if (!partialDecoding || (cpy == oend) || (ip >= (iend - 2))) + break; + } else { + /* may overwrite up to WILDCOPYLENGTH beyond cpy */ + LZ4_wildCopy(op, ip, cpy); + ip += length; + op = cpy; + } + + /* get offset */ + offset = LZ4_readLE16(ip); + ip += 2; + match = op - offset; + + /* get matchlength */ + length = token & ML_MASK; + +_copy_match: + if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) { + /* Error : offset outside buffers */ + goto _output_error; + } + + /* costs ~1%; silence an msan warning when offset == 0 */ + /* + * note : when partialDecoding, there is no guarantee that + * at least 4 bytes remain available in output buffer + */ + if (!partialDecoding) { + assert(oend > op); + assert(oend - op >= 4); + + LZ4_write32(op, (U32)offset); + } + + if (length == ML_MASK) { + unsigned int s; + + do { + s = *ip++; + + if ((endOnInput) && (ip > iend - LASTLITERALS)) + goto _output_error; + + length += s; + } while (s == 255); + + if ((safeDecode) + && unlikely( + (uptrval)(op) + length < (uptrval)op)) { + /* overflow detection */ + goto _output_error; + } + } + + length += MINMATCH; + + /* match starting within external dictionary */ + if ((dict == usingExtDict) && (match < lowPrefix)) { + if (unlikely(op + length > oend - LASTLITERALS)) { + /* doesn't respect parsing restriction */ + if (!partialDecoding) + goto _output_error; + length = min(length, (size_t)(oend - op)); + } + + if (length <= (size_t)(lowPrefix - match)) { + /* + * match fits entirely within external + * dictionary : just copy + */ + memmove(op, dictEnd - (lowPrefix - match), + length); + op += length; + } else { + /* + * match stretches into both external + * dictionary and current block + */ + size_t const copySize = (size_t)(lowPrefix - match); + size_t const restSize = length - copySize; + + LZ4_memcpy(op, dictEnd - copySize, copySize); + op += copySize; + if (restSize > (size_t)(op - lowPrefix)) { + /* overlap copy */ + BYTE * const endOfMatch = op + restSize; + const BYTE *copyFrom = lowPrefix; + + while (op < endOfMatch) + *op++ = *copyFrom++; + } else { + LZ4_memcpy(op, lowPrefix, restSize); + op += restSize; + } + } + continue; + } + + /* copy match within block */ + cpy = op + length; + + /* + * partialDecoding : + * may not respect endBlock parsing restrictions + */ + assert(op <= oend); + if (partialDecoding && + (cpy > oend - MATCH_SAFEGUARD_DISTANCE)) { + size_t const mlen = min(length, (size_t)(oend - op)); + const BYTE * const matchEnd = match + mlen; + BYTE * const copyEnd = op + mlen; + + if (matchEnd > op) { + /* overlap copy */ + while (op < copyEnd) + *op++ = *match++; + } else { + LZ4_memcpy(op, match, mlen); + } + op = copyEnd; + if (op == oend) + break; + continue; + } + + if (unlikely(offset < 8)) { + op[0] = match[0]; + op[1] = match[1]; + op[2] = match[2]; + op[3] = match[3]; + match += inc32table[offset]; + LZ4_memcpy(op + 4, match, 4); + match -= dec64table[offset]; + } else { + LZ4_copy8(op, match); + match += 8; + } + + op += 8; + + if (unlikely(cpy > oend - MATCH_SAFEGUARD_DISTANCE)) { + BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1); + + if (cpy > oend - LASTLITERALS) { + /* + * Error : last LASTLITERALS bytes + * must be literals (uncompressed) + */ + goto _output_error; + } + + if (op < oCopyLimit) { + LZ4_wildCopy(op, match, oCopyLimit); + match += oCopyLimit - op; + op = oCopyLimit; + } + while (op < cpy) + *op++ = *match++; + } else { + LZ4_copy8(op, match); + if (length > 16) + LZ4_wildCopy(op + 8, match + 8, cpy); + } + op = cpy; /* wildcopy correction */ + } + + /* end of decoding */ + if (endOnInput) { + /* Nb of output bytes decoded */ + return (int) (((char *)op) - dst); + } else { + /* Nb of input bytes read */ + return (int) (((const char *)ip) - src); + } + + /* Overflow error detected */ +_output_error: + return (int) (-(((const char *)ip) - src)) - 1; +} + +int LZ4_decompress_safe(const char *source, char *dest, + int compressedSize, int maxDecompressedSize) +{ + return LZ4_decompress_generic(source, dest, + compressedSize, maxDecompressedSize, + endOnInputSize, decode_full_block, + noDict, (BYTE *)dest, NULL, 0); +} + +int LZ4_decompress_safe_partial(const char *src, char *dst, + int compressedSize, int targetOutputSize, int dstCapacity) +{ + dstCapacity = min(targetOutputSize, dstCapacity); + return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity, + endOnInputSize, partial_decode, + noDict, (BYTE *)dst, NULL, 0); +} + +int LZ4_decompress_fast(const char *source, char *dest, int originalSize) +{ + return LZ4_decompress_generic(source, dest, 0, originalSize, + endOnOutputSize, decode_full_block, + withPrefix64k, + (BYTE *)dest - 64 * KB, NULL, 0); +} + +/* ===== Instantiate a few more decoding cases, used more than once. ===== */ + +int LZ4_decompress_safe_withPrefix64k(const char *source, char *dest, + int compressedSize, int maxOutputSize) +{ + return LZ4_decompress_generic(source, dest, + compressedSize, maxOutputSize, + endOnInputSize, decode_full_block, + withPrefix64k, + (BYTE *)dest - 64 * KB, NULL, 0); +} + +static int LZ4_decompress_safe_withSmallPrefix(const char *source, char *dest, + int compressedSize, + int maxOutputSize, + size_t prefixSize) +{ + return LZ4_decompress_generic(source, dest, + compressedSize, maxOutputSize, + endOnInputSize, decode_full_block, + noDict, + (BYTE *)dest - prefixSize, NULL, 0); +} + +int LZ4_decompress_safe_forceExtDict(const char *source, char *dest, + int compressedSize, int maxOutputSize, + const void *dictStart, size_t dictSize) +{ + return LZ4_decompress_generic(source, dest, + compressedSize, maxOutputSize, + endOnInputSize, decode_full_block, + usingExtDict, (BYTE *)dest, + (const BYTE *)dictStart, dictSize); +} + +static int LZ4_decompress_fast_extDict(const char *source, char *dest, + int originalSize, + const void *dictStart, size_t dictSize) +{ + return LZ4_decompress_generic(source, dest, + 0, originalSize, + endOnOutputSize, decode_full_block, + usingExtDict, (BYTE *)dest, + (const BYTE *)dictStart, dictSize); +} + +/* + * The "double dictionary" mode, for use with e.g. ring buffers: the first part + * of the dictionary is passed as prefix, and the second via dictStart + dictSize. + * These routines are used only once, in LZ4_decompress_*_continue(). + */ +static FORCE_INLINE +int LZ4_decompress_safe_doubleDict(const char *source, char *dest, + int compressedSize, int maxOutputSize, + size_t prefixSize, + const void *dictStart, size_t dictSize) +{ + return LZ4_decompress_generic(source, dest, + compressedSize, maxOutputSize, + endOnInputSize, decode_full_block, + usingExtDict, (BYTE *)dest - prefixSize, + (const BYTE *)dictStart, dictSize); +} + +static FORCE_INLINE +int LZ4_decompress_fast_doubleDict(const char *source, char *dest, + int originalSize, size_t prefixSize, + const void *dictStart, size_t dictSize) +{ + return LZ4_decompress_generic(source, dest, + 0, originalSize, + endOnOutputSize, decode_full_block, + usingExtDict, (BYTE *)dest - prefixSize, + (const BYTE *)dictStart, dictSize); +} + +/* ===== streaming decompression functions ===== */ + +int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode, + const char *dictionary, int dictSize) +{ + LZ4_streamDecode_t_internal *lz4sd = + &LZ4_streamDecode->internal_donotuse; + + lz4sd->prefixSize = (size_t) dictSize; + lz4sd->prefixEnd = (const BYTE *) dictionary + dictSize; + lz4sd->externalDict = NULL; + lz4sd->extDictSize = 0; + return 1; +} + +/* + * *_continue() : + * These decoding functions allow decompression of multiple blocks + * in "streaming" mode. + * Previously decoded blocks must still be available at the memory + * position where they were decoded. + * If it's not possible, save the relevant part of + * decoded data into a safe buffer, + * and indicate where it stands using LZ4_setStreamDecode() + */ +int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode, + const char *source, char *dest, int compressedSize, int maxOutputSize) +{ + LZ4_streamDecode_t_internal *lz4sd = + &LZ4_streamDecode->internal_donotuse; + int result; + + if (lz4sd->prefixSize == 0) { + /* The first call, no dictionary yet. */ + assert(lz4sd->extDictSize == 0); + result = LZ4_decompress_safe(source, dest, + compressedSize, maxOutputSize); + if (result <= 0) + return result; + lz4sd->prefixSize = result; + lz4sd->prefixEnd = (BYTE *)dest + result; + } else if (lz4sd->prefixEnd == (BYTE *)dest) { + /* They're rolling the current segment. */ + if (lz4sd->prefixSize >= 64 * KB - 1) + result = LZ4_decompress_safe_withPrefix64k(source, dest, + compressedSize, maxOutputSize); + else if (lz4sd->extDictSize == 0) + result = LZ4_decompress_safe_withSmallPrefix(source, + dest, compressedSize, maxOutputSize, + lz4sd->prefixSize); + else + result = LZ4_decompress_safe_doubleDict(source, dest, + compressedSize, maxOutputSize, + lz4sd->prefixSize, + lz4sd->externalDict, lz4sd->extDictSize); + if (result <= 0) + return result; + lz4sd->prefixSize += result; + lz4sd->prefixEnd += result; + } else { + /* + * The buffer wraps around, or they're + * switching to another buffer. + */ + lz4sd->extDictSize = lz4sd->prefixSize; + lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize; + result = LZ4_decompress_safe_forceExtDict(source, dest, + compressedSize, maxOutputSize, + lz4sd->externalDict, lz4sd->extDictSize); + if (result <= 0) + return result; + lz4sd->prefixSize = result; + lz4sd->prefixEnd = (BYTE *)dest + result; + } + + return result; +} + +int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode, + const char *source, char *dest, int originalSize) +{ + LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse; + int result; + + if (lz4sd->prefixSize == 0) { + assert(lz4sd->extDictSize == 0); + result = LZ4_decompress_fast(source, dest, originalSize); + if (result <= 0) + return result; + lz4sd->prefixSize = originalSize; + lz4sd->prefixEnd = (BYTE *)dest + originalSize; + } else if (lz4sd->prefixEnd == (BYTE *)dest) { + if (lz4sd->prefixSize >= 64 * KB - 1 || + lz4sd->extDictSize == 0) + result = LZ4_decompress_fast(source, dest, + originalSize); + else + result = LZ4_decompress_fast_doubleDict(source, dest, + originalSize, lz4sd->prefixSize, + lz4sd->externalDict, lz4sd->extDictSize); + if (result <= 0) + return result; + lz4sd->prefixSize += originalSize; + lz4sd->prefixEnd += originalSize; + } else { + lz4sd->extDictSize = lz4sd->prefixSize; + lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize; + result = LZ4_decompress_fast_extDict(source, dest, + originalSize, lz4sd->externalDict, lz4sd->extDictSize); + if (result <= 0) + return result; + lz4sd->prefixSize = originalSize; + lz4sd->prefixEnd = (BYTE *)dest + originalSize; + } + return result; +} + +int LZ4_decompress_safe_usingDict(const char *source, char *dest, + int compressedSize, int maxOutputSize, + const char *dictStart, int dictSize) +{ + if (dictSize == 0) + return LZ4_decompress_safe(source, dest, + compressedSize, maxOutputSize); + if (dictStart+dictSize == dest) { + if (dictSize >= 64 * KB - 1) + return LZ4_decompress_safe_withPrefix64k(source, dest, + compressedSize, maxOutputSize); + return LZ4_decompress_safe_withSmallPrefix(source, dest, + compressedSize, maxOutputSize, dictSize); + } + return LZ4_decompress_safe_forceExtDict(source, dest, + compressedSize, maxOutputSize, dictStart, dictSize); +} + +int LZ4_decompress_fast_usingDict(const char *source, char *dest, + int originalSize, + const char *dictStart, int dictSize) +{ + if (dictSize == 0 || dictStart + dictSize == dest) + return LZ4_decompress_fast(source, dest, originalSize); + + return LZ4_decompress_fast_extDict(source, dest, originalSize, + dictStart, dictSize); +} + +#ifndef STATIC +EXPORT_SYMBOL(LZ4_decompress_safe); +EXPORT_SYMBOL(LZ4_decompress_safe_partial); +EXPORT_SYMBOL(LZ4_decompress_fast); +EXPORT_SYMBOL(LZ4_setStreamDecode); +EXPORT_SYMBOL(LZ4_decompress_safe_continue); +EXPORT_SYMBOL(LZ4_decompress_fast_continue); +EXPORT_SYMBOL(LZ4_decompress_safe_usingDict); +EXPORT_SYMBOL(LZ4_decompress_fast_usingDict); + +MODULE_LICENSE("Dual BSD/GPL"); +MODULE_DESCRIPTION("LZ4 decompressor"); +#endif |