Merge pull request #2405 from senhuang42/sequence_compression_minmatch_fix
Sequence Compression API - make validator use cctx minMatch instead of global MINMATCH
diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 239af1d..92f0308 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -4524,7 +4524,7 @@
/* Returns a ZSTD error code if sequence is not valid */
static size_t ZSTD_validateSequence(U32 offCode, U32 matchLength,
- size_t posInSrc, U32 windowLog, size_t dictSize) {
+ size_t posInSrc, U32 windowLog, size_t dictSize, U32 minMatch) {
size_t offsetBound;
U32 windowSize = 1 << windowLog;
/* posInSrc represents the amount of data the the decoder would decode up to this point.
@@ -4534,7 +4534,7 @@
*/
offsetBound = posInSrc > windowSize ? (size_t)windowSize : posInSrc + (size_t)dictSize;
RETURN_ERROR_IF(offCode > offsetBound + ZSTD_REP_MOVE, corruption_detected, "Offset too large!");
- RETURN_ERROR_IF(matchLength < MINMATCH, corruption_detected, "Matchlength too small");
+ RETURN_ERROR_IF(matchLength < minMatch, corruption_detected, "Matchlength too small");
return 0;
}
@@ -4594,7 +4594,8 @@
if (cctx->appliedParams.validateSequences) {
seqPos->posInSrc += litLength + matchLength;
FORWARD_IF_ERROR(ZSTD_validateSequence(offCode, matchLength, seqPos->posInSrc,
- cctx->appliedParams.cParams.windowLog, dictSize),
+ cctx->appliedParams.cParams.windowLog, dictSize,
+ cctx->appliedParams.cParams.minMatch),
"Sequence validation failed");
}
ZSTD_storeSeq(&cctx->seqStore, litLength, ip, iend, offCode, matchLength - MINMATCH);
@@ -4679,13 +4680,13 @@
U32 firstHalfMatchLength;
litLength = startPosInSequence >= litLength ? 0 : litLength - startPosInSequence;
firstHalfMatchLength = endPosInSequence - startPosInSequence - litLength;
- if (matchLength > blockSize && firstHalfMatchLength >= MINMATCH) {
+ if (matchLength > blockSize && firstHalfMatchLength >= cctx->appliedParams.cParams.minMatch) {
/* Only ever split the match if it is larger than the block size */
U32 secondHalfMatchLength = currSeq.matchLength + currSeq.litLength - endPosInSequence;
- if (secondHalfMatchLength < MINMATCH) {
- /* Move the endPosInSequence backward so that it creates match of MINMATCH length */
- endPosInSequence -= MINMATCH - secondHalfMatchLength;
- bytesAdjustment = MINMATCH - secondHalfMatchLength;
+ if (secondHalfMatchLength < cctx->appliedParams.cParams.minMatch) {
+ /* Move the endPosInSequence backward so that it creates match of minMatch length */
+ endPosInSequence -= cctx->appliedParams.cParams.minMatch - secondHalfMatchLength;
+ bytesAdjustment = cctx->appliedParams.cParams.minMatch - secondHalfMatchLength;
firstHalfMatchLength -= bytesAdjustment;
}
matchLength = firstHalfMatchLength;
@@ -4716,7 +4717,8 @@
if (cctx->appliedParams.validateSequences) {
seqPos->posInSrc += litLength + matchLength;
FORWARD_IF_ERROR(ZSTD_validateSequence(offCode, matchLength, seqPos->posInSrc,
- cctx->appliedParams.cParams.windowLog, dictSize),
+ cctx->appliedParams.cParams.windowLog, dictSize,
+ cctx->appliedParams.cParams.minMatch),
"Sequence validation failed");
}
DEBUGLOG(6, "Storing sequence: (of: %u, ml: %u, ll: %u)", offCode, matchLength, litLength);
@@ -4884,6 +4886,7 @@
DEBUGLOG(3, "ZSTD_compressSequences()");
assert(cctx != NULL);
FORWARD_IF_ERROR(ZSTD_CCtx_init_compressStream2(cctx, ZSTD_e_end, srcSize), "CCtx initialization failed");
+ RETURN_ERROR_IF(inSeqsSize > cctx->seqStore.maxNbSeq, memory_allocation, "Not enough memory allocated. Try adjusting ZSTD_c_minMatch.");
/* Begin writing output, starting with frame header */
frameHeaderSize = ZSTD_writeFrameHeader(op, dstCapacity, &cctx->appliedParams, srcSize, cctx->dictID);
op += frameHeaderSize;
diff --git a/lib/zstd.h b/lib/zstd.h
index 1b525bd..b99ce97 100644
--- a/lib/zstd.h
+++ b/lib/zstd.h
@@ -1356,9 +1356,10 @@
* behavior. If ZSTD_c_validateSequences == 1, then if sequence is invalid (see doc/zstd_compression_format.md for
* specifics regarding offset/matchlength requirements) then the function will bail out and return an error.
*
- * In addition to the two adjustable experimental params, other noteworthy cctx parameters are the compression level and window log.
- * - The compression level accordingly adjusts the strength of the entropy coder, as it would in typical compression.
- * - The window log affects offset validation: this function will return an error at higher debug levels if a provided offset
+ * In addition to the two adjustable experimental params, there are other important cctx params.
+ * - ZSTD_c_minMatch MUST be set as less than or equal to the smallest match generated by the match finder. It has a minimum value of ZSTD_MINMATCH_MIN.
+ * - ZSTD_c_compressionLevel accordingly adjusts the strength of the entropy coder, as it would in typical compression.
+ * - ZSTD_c_windowLog affects offset validation: this function will return an error at higher debug levels if a provided offset
* is larger than what the spec allows for a given window log and dictionary (if present). See: doc/zstd_compression_format.md
*
* Note: Repcodes are, as of now, always re-calculated within this function, so ZSTD_Sequence::rep is unused.
diff --git a/tests/fuzz/sequence_compression_api.c b/tests/fuzz/sequence_compression_api.c
index e22c11c..e838687 100644
--- a/tests/fuzz/sequence_compression_api.c
+++ b/tests/fuzz/sequence_compression_api.c
@@ -199,6 +199,7 @@
ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, cLevel);
ZSTD_CCtx_setParameter(cctx, ZSTD_c_windowLog, wLog);
ZSTD_CCtx_setParameter(cctx, ZSTD_c_minMatch, ZSTD_MINMATCH_MIN);
+ ZSTD_CCtx_setParameter(cctx, ZSTD_c_validateSequences, 1);
/* TODO: Add block delim mode fuzzing */
ZSTD_CCtx_setParameter(cctx, ZSTD_c_blockDelimiters, ZSTD_sf_noBlockDelimiters);
if (hasDict) {