diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c index 8308bf5d1..df4e828cd 100644 --- a/lib/compress/zstd_compress.c +++ b/lib/compress/zstd_compress.c @@ -1334,6 +1334,7 @@ static size_t ZSTD_continueCCtx(ZSTD_CCtx* cctx, ZSTD_CCtx_params params, U64 pl cctx->blockState.matchState.cParams = params.cParams; cctx->pledgedSrcSizePlusOne = pledgedSrcSize+1; cctx->consumedSrcSize = 0; + cctx->isFirstBlock = 1; cctx->producedCSize = 0; if (pledgedSrcSize == ZSTD_CONTENTSIZE_UNKNOWN) cctx->appliedParams.fParams.contentSizeFlag = 0; @@ -1436,6 +1437,7 @@ static size_t ZSTD_resetCCtx_internal(ZSTD_CCtx* zc, (U32)pledgedSrcSize, params.cParams.windowLog); assert(!ZSTD_isError(ZSTD_checkCParams(params.cParams))); + zc->isFirstBlock = 1; if (crp == ZSTDcrp_continue) { if (ZSTD_equivalentParams(zc->appliedParams, params, zc->inBuffSize, @@ -2289,11 +2291,28 @@ static size_t ZSTD_buildSeqStore(ZSTD_CCtx* zc, const void* src, size_t srcSize) return ZSTDbss_compress; } +/* Returns true if the given block is a RLE block */ +static int ZSTD_isRLE(const BYTE *ip, size_t length) { + size_t i; + if (length < 2) return 1; + for (i = 1; i < length; ++i) { + if (ip[0] != ip[i]) return 0; + } + return 1; +} + static size_t ZSTD_compressBlock_internal(ZSTD_CCtx* zc, void* dst, size_t dstCapacity, - const void* src, size_t srcSize) + const void* src, size_t srcSize, U32 frame) { + /* This the upper bound for the length of an rle block. + * This isn't the actual upper bound. Finding the real threshold + * needs further investigation. + */ + const U32 rleMaxLength = 25; size_t cSize; + const BYTE* ip = (const BYTE*)src; + BYTE* op = (BYTE*)dst; DEBUGLOG(5, "ZSTD_compressBlock_internal (dstCapacity=%u, dictLimit=%u, nextToUpdate=%u)", (unsigned)dstCapacity, (unsigned)zc->blockState.matchState.window.dictLimit, (unsigned)zc->blockState.matchState.nextToUpdate); @@ -2312,8 +2331,21 @@ static size_t ZSTD_compressBlock_internal(ZSTD_CCtx* zc, zc->entropyWorkspace, HUF_WORKSPACE_SIZE /* statically allocated in resetCCtx */, zc->bmi2); + if (frame && + /* We don't want to emit our first block as a RLE even if it qualifies because + * doing so will cause the decoder to throw a "should consume all input error." + * https://github.com/facebook/zstd/blob/dev/programs/fileio.c#L1723 + */ + !zc->isFirstBlock && + cSize < rleMaxLength && + ZSTD_isRLE(ip, srcSize)) + { + cSize = 1; + op[0] = ip[0]; + } + out: - if (!ZSTD_isError(cSize) && cSize != 0) { + if (!ZSTD_isError(cSize) && cSize > 1) { /* confirm repcodes and entropy tables when emitting a compressed block */ ZSTD_compressedBlockState_t* const tmp = zc->blockState.prevCBlock; zc->blockState.prevCBlock = zc->blockState.nextCBlock; @@ -2348,7 +2380,6 @@ static void ZSTD_overflowCorrectIfNeeded(ZSTD_matchState_t* ms, ZSTD_CCtx_params } } - /*! ZSTD_compress_frameChunk() : * Compress a chunk of data into one or multiple blocks. * All blocks will be terminated, all input will be consumed. @@ -2390,15 +2421,17 @@ static size_t ZSTD_compress_frameChunk (ZSTD_CCtx* cctx, { size_t cSize = ZSTD_compressBlock_internal(cctx, op+ZSTD_blockHeaderSize, dstCapacity-ZSTD_blockHeaderSize, - ip, blockSize); + ip, blockSize, 1 /* frame */); FORWARD_IF_ERROR(cSize); if (cSize == 0) { /* block is not compressible */ cSize = ZSTD_noCompressBlock(op, dstCapacity, ip, blockSize, lastBlock); FORWARD_IF_ERROR(cSize); } else { - U32 const cBlockHeader24 = lastBlock + (((U32)bt_compressed)<<1) + (U32)(cSize << 3); - MEM_writeLE24(op, cBlockHeader24); + const U32 cBlockHeader = cSize == 1 ? + lastBlock + (((U32)bt_rle)<<1) + (U32)(blockSize << 3) : + lastBlock + (((U32)bt_compressed)<<1) + (U32)(cSize << 3); + MEM_writeLE24(op, cBlockHeader); cSize += ZSTD_blockHeaderSize; } @@ -2408,6 +2441,7 @@ static size_t ZSTD_compress_frameChunk (ZSTD_CCtx* cctx, op += cSize; assert(dstCapacity >= cSize); dstCapacity -= cSize; + cctx->isFirstBlock = 0; DEBUGLOG(5, "ZSTD_compress_frameChunk: adding a block of size %u", (unsigned)cSize); } } @@ -2528,7 +2562,7 @@ static size_t ZSTD_compressContinue_internal (ZSTD_CCtx* cctx, DEBUGLOG(5, "ZSTD_compressContinue_internal (blockSize=%u)", (unsigned)cctx->blockSize); { size_t const cSize = frame ? ZSTD_compress_frameChunk (cctx, dst, dstCapacity, src, srcSize, lastFrameChunk) : - ZSTD_compressBlock_internal (cctx, dst, dstCapacity, src, srcSize); + ZSTD_compressBlock_internal (cctx, dst, dstCapacity, src, srcSize, 0 /* frame */); FORWARD_IF_ERROR(cSize); cctx->consumedSrcSize += srcSize; cctx->producedCSize += (cSize + fhSize); diff --git a/lib/compress/zstd_compress_internal.h b/lib/compress/zstd_compress_internal.h index 3e590ec37..8bffa6a12 100644 --- a/lib/compress/zstd_compress_internal.h +++ b/lib/compress/zstd_compress_internal.h @@ -241,6 +241,7 @@ struct ZSTD_CCtx_s { XXH64_state_t xxhState; ZSTD_customMem customMem; size_t staticSize; + int isFirstBlock; seqStore_t seqStore; /* sequences storage ptrs */ ldmState_t ldmState; /* long distance matching state */ diff --git a/tests/fuzzer.c b/tests/fuzzer.c index 4788c356a..fe656e6c7 100644 --- a/tests/fuzzer.c +++ b/tests/fuzzer.c @@ -1960,6 +1960,19 @@ static int basicUnitTests(U32 const seed, double compressibility) DISPLAYLEVEL(3, "OK \n"); } + /* Multiple blocks of zeros test */ + #define LONGZEROSLENGTH 1000000 /* 1MB of zeros */ + DISPLAYLEVEL(3, "test%3i : compress %u zeroes : ", testNb++, LONGZEROSLENGTH); + memset(CNBuffer, 0, LONGZEROSLENGTH); + CHECK_VAR(cSize, ZSTD_compress(compressedBuffer, ZSTD_compressBound(LONGZEROSLENGTH), CNBuffer, LONGZEROSLENGTH, 1) ); + DISPLAYLEVEL(3, "OK (%u bytes : %.2f%%)\n", (unsigned)cSize, (double)cSize/LONGZEROSLENGTH*100); + + DISPLAYLEVEL(3, "test%3i : decompress %u zeroes : ", testNb++, LONGZEROSLENGTH); + { CHECK_NEWV(r, ZSTD_decompress(decodedBuffer, LONGZEROSLENGTH, compressedBuffer, cSize) ); + if (r != LONGZEROSLENGTH) goto _output_error; } + DISPLAYLEVEL(3, "OK \n"); + + /* All zeroes test (test bug #137) */ #define ZEROESLENGTH 100 DISPLAYLEVEL(3, "test%3i : compress %u zeroes : ", testNb++, ZEROESLENGTH);