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Merge pull request #756 from terrelln/destSize

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[LZ4_compress_destSize + multi-blocks streaming] Fix rare data corruption bug
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Yann Collet 2019-07-17 13:25:41 -07:00 committed by GitHub
commit 19b099986a
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1 changed files with 32 additions and 2 deletions
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34
lib/lz4.c
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@ -648,6 +648,18 @@ LZ4_FORCE_INLINE U32 LZ4_hashPosition(const void* const p, tableType_t const tab
return LZ4_hash4(LZ4_read32(p), tableType);
}
static void LZ4_clearHash(U32 h, void* tableBase, tableType_t const tableType)
{
switch (tableType)
{
default: /* fallthrough */
case clearedTable: { /* illegal! */ assert(0); return; }
case byPtr: { const BYTE** hashTable = (const BYTE**)tableBase; hashTable[h] = NULL; return; }
case byU32: { U32* hashTable = (U32*) tableBase; hashTable[h] = 0; return; }
case byU16: { U16* hashTable = (U16*) tableBase; hashTable[h] = 0; return; }
}
}
static void LZ4_putIndexOnHash(U32 idx, U32 h, void* tableBase, tableType_t const tableType)
{
switch (tableType)
@ -848,6 +860,7 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
for ( ; ; ) {
const BYTE* match;
BYTE* token;
const BYTE* filledIp;
/* Find a match */
if (tableType == byPtr) {
@ -934,6 +947,7 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
}
/* Catch up */
filledIp = ip;
while (((ip>anchor) & (match > lowLimit)) && (unlikely(ip[-1]==match[-1]))) { ip--; match--; }
/* Encode Literals */
@ -1013,12 +1027,26 @@ _next_match:
}
if ((outputDirective) && /* Check output buffer overflow */
(unlikely(op + (1 + LASTLITERALS) + (matchCode>>8) > olimit)) ) {
(unlikely(op + (1 + LASTLITERALS) + (matchCode+240)/255 > olimit)) ) {
if (outputDirective == fillOutput) {
/* Match description too long : reduce it */
U32 newMatchCode = 15 /* in token */ - 1 /* to avoid needing a zero byte */ + ((U32)(olimit - op) - 2 - 1 - LASTLITERALS) * 255;
U32 newMatchCode = 15 /* in token */ - 1 /* to avoid needing a zero byte */ + ((U32)(olimit - op) - 1 - LASTLITERALS) * 255;
ip -= matchCode - newMatchCode;
assert(newMatchCode < matchCode);
matchCode = newMatchCode;
if (unlikely(ip < filledIp)) {
/* We have already filled up to filledIp so if ip ends up less than filledIp
* we have positions in the hash table beyond the current position. This is
* a problem if we reuse the hash table. So we have to remove these positions
* from the hash table.
*/
const BYTE* ptr;
DEBUGLOG(5, "Clearing %u positions", (U32)(filledIp - ip));
for (ptr = ip + 1; ptr <= filledIp; ++ptr) {
U32 const h = LZ4_hashPosition(ptr, tableType);
LZ4_clearHash(h, cctx->hashTable, tableType);
}
}
} else {
assert(outputDirective == limitedOutput);
return 0; /* cannot compress within `dst` budget. Stored indexes in hash table are nonetheless fine */
@ -1038,6 +1066,8 @@ _next_match:
} else
*token += (BYTE)(matchCode);
}
/* Ensure we have enough space for the last literals. */
assert(!(outputDirective == fillOutput && op + 1 + LASTLITERALS > olimit));
anchor = ip;