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Merge pull request #2820 from terrelln/nb-compares

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[binary-tree] Fix underflow of nbCompares
This commit is contained in:
Nick Terrell
2021-10-11 09:59:57 -07:00
committed by GitHub
parent 26486db9ab c6c482fe07
commit b77d95b053
3 changed files with 30 additions and 26 deletions
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lib/compress/zstd_lazy.c
+6 -3
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@@ -93,7 +93,7 @@ ZSTD_insertDUBT1(const ZSTD_matchState_t* ms,
assert(curr >= btLow);
assert(ip < iend); /* condition for ZSTD_count */
while (nbCompares-- && (matchIndex > windowLow)) {
for (; nbCompares && (matchIndex > windowLow); --nbCompares) {
U32* const nextPtr = bt + 2*(matchIndex & btMask);
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
assert(matchIndex < curr);
@@ -185,7 +185,7 @@ ZSTD_DUBT_findBetterDictMatch (
(void)dictMode;
assert(dictMode == ZSTD_dictMatchState);
while (nbCompares-- && (dictMatchIndex > dictLowLimit)) {
for (; nbCompares && (dictMatchIndex > dictLowLimit); --nbCompares) {
U32* const nextPtr = dictBt + 2*(dictMatchIndex & btMask);
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
const BYTE* match = dictBase + dictMatchIndex;
@@ -309,7 +309,7 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
matchIndex = hashTable[h];
hashTable[h] = curr; /* Update Hash Table */
while (nbCompares-- && (matchIndex > windowLow)) {
for (; nbCompares && (matchIndex > windowLow); --nbCompares) {
U32* const nextPtr = bt + 2*(matchIndex & btMask);
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
const BYTE* match;
@@ -357,6 +357,7 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
*smallerPtr = *largerPtr = 0;
assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
if (dictMode == ZSTD_dictMatchState && nbCompares) {
bestLength = ZSTD_DUBT_findBetterDictMatch(
ms, ip, iend,
@@ -758,6 +759,7 @@ size_t ZSTD_HcFindBestMatch_generic (
matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
}
assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
if (dictMode == ZSTD_dedicatedDictSearch) {
ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts, dms,
ip, iLimit, prefixStart, curr, dictLimit, ddsIdx);
@@ -1356,6 +1358,7 @@ size_t ZSTD_RowFindBestMatch_generic (
}
}
assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
if (dictMode == ZSTD_dedicatedDictSearch) {
ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts + ddsExtraAttempts, dms,
ip, iLimit, prefixStart, curr, dictLimit, ddsIdx);