From 6d32240b2e9cb921f9b34b790d787d0ee1ea51cb Mon Sep 17 00:00:00 2001 From: Yann Collet Date: Mon, 10 Sep 2018 17:36:40 -0700 Subject: clarify constant MFLIMIT and separate it from MATCH_SAFEGUARD_DISTANCE. While both constants have same value, they do not seve same purpose, hence should not be confused. --- lib/lz4.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/lib/lz4.c b/lib/lz4.c index 133501d..4046102 100644 --- a/lib/lz4.c +++ b/lib/lz4.c @@ -297,8 +297,9 @@ void LZ4_wildCopy(void* dstPtr, const void* srcPtr, void* dstEnd) #define MINMATCH 4 #define WILDCOPYLENGTH 8 -#define LASTLITERALS 5 -#define MFLIMIT (WILDCOPYLENGTH+MINMATCH) +#define LASTLITERALS 5 /* see ../doc/lz4_Block_format.md#parsing-restrictions */ +#define MFLIMIT 12 /* see ../doc/lz4_Block_format.md#parsing-restrictions */ +#define MATCH_SAFEGUARD_DISTANCE ((2*WILDCOPYLENGTH) - MINMATCH) /* ensure it's possible to write 2 x wildcopyLength without overflowing output buffer */ static const int LZ4_minLength = (MFLIMIT+1); #define KB *(1 <<10) @@ -1588,7 +1589,7 @@ _copy_match: /* partialDecoding : may not respect endBlock parsing restrictions */ assert(op<=oend); - if (partialDecoding && (cpy > oend-12)) { + if (partialDecoding && (cpy > oend-MATCH_SAFEGUARD_DISTANCE)) { size_t const mlen = MIN(length, (size_t)(oend-op)); const BYTE* const matchEnd = match + mlen; BYTE* const copyEnd = op + mlen; @@ -1616,7 +1617,7 @@ _copy_match: } op += 8; - if (unlikely(cpy > oend-12)) { + if (unlikely(cpy > oend-MATCH_SAFEGUARD_DISTANCE)) { BYTE* const oCopyLimit = oend - (WILDCOPYLENGTH-1); if (cpy > oend-LASTLITERALS) goto _output_error; /* Error : last LASTLITERALS bytes must be literals (uncompressed) */ if (op < oCopyLimit) { -- cgit v0.12