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Intial commit to address 3090. Added support to decompress empty block. (#3118) 

* Intial commit to address 3090. Added support to decompress empty block

* Update zstd_decompress_block.c

Addressed review comments for the case of 'set_basic'

* Update lib/decompress/zstd_decompress_block.c

Co-authored-by: Nick Terrell <nickrterrell@gmail.com>

* Update lib/decompress/zstd_decompress_block.c

Co-authored-by: Nick Terrell <nickrterrell@gmail.com>

Co-authored-by: Nick Terrell <nickrterrell@gmail.com>
dev
udayanbapat 2022-07-14 11:54:34 -07:00 committed by GitHub
parent 02ef78be58
commit 43f21a600e
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 18 additions and 7 deletions
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2
lib/common/zstd_internal.h
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@ -93,7 +93,7 @@ typedef enum { bt_raw, bt_rle, bt_compressed, bt_reserved } blockType_e;
#define ZSTD_FRAMECHECKSUMSIZE 4
#define MIN_SEQUENCES_SIZE 1 /* nbSeq==0 */
#define MIN_CBLOCK_SIZE (1 /*litCSize*/ + 1 /* RLE or RAW */ + MIN_SEQUENCES_SIZE /* nbSeq==0 */) /* for a non-null block */
#define MIN_CBLOCK_SIZE (1 /*litCSize*/ + 1 /* RLE or RAW */) /* for a non-null block */
typedef enum { set_basic, set_rle, set_compressed, set_repeat } symbolEncodingType_e;

12
lib/compress/zstd_compress.c
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@ -2863,7 +2863,9 @@ static size_t ZSTD_buildSeqStore(ZSTD_CCtx* zc, const void* src, size_t srcSize)
assert(srcSize <= ZSTD_BLOCKSIZE_MAX);
/* Assert that we have correctly flushed the ctx params into the ms's copy */
ZSTD_assertEqualCParams(zc->appliedParams.cParams, ms->cParams);
if (srcSize < MIN_CBLOCK_SIZE+ZSTD_blockHeaderSize+1) {
/* TODO: See 3090. We reduced MIN_CBLOCK_SIZE from 3 to 2 so to compensate we are adding
* additional 1. We need to revisit and change this logic to be more consistent */
if (srcSize < MIN_CBLOCK_SIZE+ZSTD_blockHeaderSize+1+1) {
if (zc->appliedParams.cParams.strategy >= ZSTD_btopt) {
ZSTD_ldm_skipRawSeqStoreBytes(&zc->externSeqStore, srcSize);
} else {
@ -4000,7 +4002,9 @@ static size_t ZSTD_compress_frameChunk(ZSTD_CCtx* cctx,
ZSTD_matchState_t* const ms = &cctx->blockState.matchState;
U32 const lastBlock = lastFrameChunk & (blockSize >= remaining);
RETURN_ERROR_IF(dstCapacity < ZSTD_blockHeaderSize + MIN_CBLOCK_SIZE,
/* TODO: See 3090. We reduced MIN_CBLOCK_SIZE from 3 to 2 so to compensate we are adding
* additional 1. We need to revisit and change this logic to be more consistent */
RETURN_ERROR_IF(dstCapacity < ZSTD_blockHeaderSize + MIN_CBLOCK_SIZE + 1,
dstSize_tooSmall,
"not enough space to store compressed block");
if (remaining < blockSize) blockSize = remaining;
@ -6215,7 +6219,9 @@ ZSTD_compressSequences_internal(ZSTD_CCtx* cctx,
blockSize -= additionalByteAdjustment;
/* If blocks are too small, emit as a nocompress block */
if (blockSize < MIN_CBLOCK_SIZE+ZSTD_blockHeaderSize+1) {
/* TODO: See 3090. We reduced MIN_CBLOCK_SIZE from 3 to 2 so to compensate we are adding
* additional 1. We need to revisit and change this logic to be more consistent */
if (blockSize < MIN_CBLOCK_SIZE+ZSTD_blockHeaderSize+1+1) {
cBlockSize = ZSTD_noCompressBlock(op, dstCapacity, ip, blockSize, lastBlock);
FORWARD_IF_ERROR(cBlockSize, "Nocompress block failed");
DEBUGLOG(5, "Block too small, writing out nocompress block: cSize: %zu", cBlockSize);

6
lib/decompress/zstd_decompress_block.c
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@ -135,7 +135,7 @@ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
ZSTD_FALLTHROUGH;
case set_compressed:
RETURN_ERROR_IF(srcSize < 5, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need up to 5 for case 3");
RETURN_ERROR_IF(srcSize < 5, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 2; here we need up to 5 for case 3");
{ size_t lhSize, litSize, litCSize;
U32 singleStream=0;
U32 const lhlCode = (istart[0] >> 2) & 3;
@ -238,6 +238,7 @@ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
break;
case 3:
lhSize = 3;
RETURN_ERROR_IF(srcSize<3, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 2; here we need lhSize = 3");
litSize = MEM_readLE24(istart) >> 4;
break;
}
@ -280,12 +281,13 @@ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
break;
case 1:
lhSize = 2;
RETURN_ERROR_IF(srcSize<3, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 2; here we need lhSize+1 = 3");
litSize = MEM_readLE16(istart) >> 4;
break;
case 3:
lhSize = 3;
RETURN_ERROR_IF(srcSize<4, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 2; here we need lhSize+1 = 4");
litSize = MEM_readLE24(istart) >> 4;
RETURN_ERROR_IF(srcSize<4, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4");
break;
}
RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled");

BIN
tests/golden-decompression/empty-block.zst Normal file
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Binary file not shown.

5
tests/playTests.sh
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@ -418,8 +418,11 @@ println "\n===> decompression only tests "
dd bs=1048576 count=1 if=/dev/zero of=tmp
zstd -d -o tmp1 "$TESTDIR/golden-decompression/rle-first-block.zst"
$DIFF -s tmp1 tmp
rm -f tmp*
touch tmp_empty
zstd -d -o tmp2 "$TESTDIR/golden-decompression/empty-block.zst"
$DIFF -s tmp2 tmp_empty
rm -f tmp*
println "\n===> compress multiple files"
println hello > tmp1