diff options
| -rw-r--r-- | lib/lz4.c | 30 |
1 files changed, 30 insertions, 0 deletions
@@ -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 */ @@ -1018,7 +1032,21 @@ _next_match: /* Match description too long : reduce it */ 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; |