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Hardcode repcode safety check, fix cosmetic nits

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This commit is contained in:
Elliot Gorokhovsky 2022-04-26 17:54:25 -04:00
parent 809f652912
commit 518cb83833
1 changed files with 27 additions and 10 deletions
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33
lib/compress/zstd_fast.c
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@ -581,13 +581,13 @@ size_t ZSTD_compressBlock_fast_dictMatchState(
static size_t ZSTD_compressBlock_fast_extDict_generic( static size_t ZSTD_compressBlock_fast_extDict_generic(
ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
void const* src, size_t srcSize, U32 const mls, U32 const hasStep) void const* src, size_t srcSize, U32 const mls, U32 const commonScenario)
{ {
const ZSTD_compressionParameters* const cParams = &ms->cParams; const ZSTD_compressionParameters* const cParams = &ms->cParams;
U32* const hashTable = ms->hashTable; U32* const hashTable = ms->hashTable;
U32 const hlog = cParams->hashLog; U32 const hlog = cParams->hashLog;
/* support stepSize of 0 */ /* support stepSize of 0 */
size_t const stepSize = hasStep ? (cParams->targetLength + !(cParams->targetLength) + 1) : 2; size_t const stepSize = commonScenario ? 2 : (cParams->targetLength + !(cParams->targetLength) + 1);
const BYTE* const base = ms->window.base; const BYTE* const base = ms->window.base;
const BYTE* const dictBase = ms->window.dictBase; const BYTE* const dictBase = ms->window.dictBase;
const BYTE* const istart = (const BYTE*)src; const BYTE* const istart = (const BYTE*)src;
@ -633,9 +633,13 @@ static size_t ZSTD_compressBlock_fast_extDict_generic(
{ U32 const curr = (U32)(ip0 - base); { U32 const curr = (U32)(ip0 - base);
U32 const maxRep = curr - dictStartIndex; U32 const maxRep = curr - dictStartIndex;
if (commonScenario) {
assert(offset_2 < maxRep);
assert(offset_1 < maxRep);
} else {
if (offset_2 >= maxRep) offset_2 = 0; if (offset_2 >= maxRep) offset_2 = 0;
if (offset_1 >= maxRep) offset_1 = 0; if (offset_1 >= maxRep) offset_1 = 0;
} } }
/* start each op */ /* start each op */
_start: /* Requires: ip0 */ _start: /* Requires: ip0 */
@ -665,7 +669,7 @@ _start: /* Requires: ip0 */
const BYTE* const repBase = repIndex < prefixStartIndex ? dictBase : base; const BYTE* const repBase = repIndex < prefixStartIndex ? dictBase : base;
U32 rval; U32 rval;
if ( ((U32)(prefixStartIndex - repIndex) >= 4) /* intentional underflow */ if ( ((U32)(prefixStartIndex - repIndex) >= 4) /* intentional underflow */
& (offset_1 > 0) ) { & (commonScenario | (offset_1 > 0)) ) {
rval = MEM_read32(repBase + repIndex); rval = MEM_read32(repBase + repIndex);
} else { } else {
rval = MEM_read32(ip2) ^ 1; /* guaranteed to not match. */ rval = MEM_read32(ip2) ^ 1; /* guaranteed to not match. */
@ -690,7 +694,9 @@ _start: /* Requires: ip0 */
} } } }
{ /* load match for ip[0] */ { /* load match for ip[0] */
U32 const mval = idx >= dictStartIndex ? MEM_read32(idxBase + idx) : MEM_read32(ip0) ^ 1; /* guaranteed not to match */ U32 const mval = idx >= dictStartIndex ?
MEM_read32(idxBase + idx) :
MEM_read32(ip0) ^ 1; /* guaranteed not to match */
/* check match at ip[0] */ /* check match at ip[0] */
if (MEM_read32(ip0) == mval) { if (MEM_read32(ip0) == mval) {
@ -716,7 +722,9 @@ _start: /* Requires: ip0 */
hashTable[hash0] = current0; hashTable[hash0] = current0;
{ /* load match for ip[0] */ { /* load match for ip[0] */
U32 const mval = idx >= dictStartIndex ? MEM_read32(idxBase + idx) : MEM_read32(ip0) ^ 1; /* guaranteed not to match */ U32 const mval = idx >= dictStartIndex ?
MEM_read32(idxBase + idx) :
MEM_read32(ip0) ^ 1; /* guaranteed not to match */
/* check match at ip[0] */ /* check match at ip[0] */
if (MEM_read32(ip0) == mval) { if (MEM_read32(ip0) == mval) {
@ -804,7 +812,7 @@ _match: /* Requires: ip0, match0, offcode, matchEnd */
while (ip0 <= ilimit) { while (ip0 <= ilimit) {
U32 const repIndex2 = (U32)(ip0-base) - offset_2; U32 const repIndex2 = (U32)(ip0-base) - offset_2;
const BYTE* const repMatch2 = repIndex2 < prefixStartIndex ? dictBase + repIndex2 : base + repIndex2; const BYTE* const repMatch2 = repIndex2 < prefixStartIndex ? dictBase + repIndex2 : base + repIndex2;
if ( (((U32)((prefixStartIndex-1) - repIndex2) >= 3) & (offset_2 > 0)) /* intentional underflow */ if ( (((U32)((prefixStartIndex-1) - repIndex2) >= 3) & (commonScenario | (offset_2 > 0))) /* intentional underflow */
&& (MEM_read32(repMatch2) == MEM_read32(ip0)) ) { && (MEM_read32(repMatch2) == MEM_read32(ip0)) ) {
const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend; const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
size_t const repLength2 = ZSTD_count_2segments(ip0+4, repMatch2+4, iend, repEnd2, prefixStart) + 4; size_t const repLength2 = ZSTD_count_2segments(ip0+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
@ -836,8 +844,17 @@ size_t ZSTD_compressBlock_fast_extDict(
void const* src, size_t srcSize) void const* src, size_t srcSize)
{ {
U32 const mls = ms->cParams.minMatch; U32 const mls = ms->cParams.minMatch;
const BYTE* const istart = (const BYTE*)src;
const BYTE* const base = ms->window.base;
const U32 endIndex = (U32)((size_t)(istart - base) + srcSize);
const U32 lowLimit = ZSTD_getLowestMatchIndex(ms, endIndex, ms->cParams.windowLog);
U32 const curr = (U32)(istart - base);
U32 const maxRep = curr - lowLimit;
U32 const repOffsetsAreValid = (rep[0] < maxRep) & (rep[1] < maxRep);
assert((rep[0] > 0) & (rep[1] > 0));
assert(ms->dictMatchState == NULL); assert(ms->dictMatchState == NULL);
if (ms->cParams.targetLength > 1) { if ((ms->cParams.targetLength <= 1) & repOffsetsAreValid) {
switch (mls) { switch (mls) {
default: /* includes case 3 */ default: /* includes case 3 */
case 4 : case 4 :