From: W. Felix Handte <w@felixhandte.com>
Date: Fri, 15 Jun 2018 18:08:58 +0000 (-0400)
Subject: Make Sure Position 0 Gets Into the Tree
X-Git-Tag: v1.3.5~3^2~10^2~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f0a13bcd68466f230ac5bc4dc92854779b5bc285;p=thirdparty%2Fzstd.git

Make Sure Position 0 Gets Into the Tree
---

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 01ba01bda..216196ed6 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -966,6 +966,7 @@ static void ZSTD_invalidateMatchState(ZSTD_matchState_t* ms)
     ZSTD_window_clear(&ms->window);
 
     ms->nextToUpdate = ms->window.dictLimit + 1;
+    ms->nextToUpdate3 = ms->window.dictLimit + 1;
     ms->loadedDictEnd = 0;
     ms->opt.litLengthSum = 0;  /* force reset of btopt stats */
     ms->dictMatchState = NULL;
diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index c22ddeb53..92805b9b2 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -384,6 +384,7 @@ static U32 ZSTD_insertBt1(
     U32* largerPtr  = smallerPtr + 1;
     U32 dummy32;   /* to be nullified at the end */
     U32 const windowLow = ms->window.lowLimit;
+    U32 const matchLow = windowLow ? windowLow : 1;
     U32 matchEndIdx = current+8+1;
     size_t bestLength = 8;
     U32 nbCompares = 1U << cParams->searchLog;
@@ -399,7 +400,7 @@ static U32 ZSTD_insertBt1(
     assert(ip <= iend-8);   /* required for h calculation */
     hashTable[h] = current;   /* Update Hash Table */
 
-    while (nbCompares-- && (matchIndex > windowLow)) {
+    while (nbCompares-- && (matchIndex >= matchLow)) {
         U32* const nextPtr = bt + 2*(matchIndex & btMask);
         size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger);   /* guaranteed minimum nb of common bytes */
         assert(matchIndex < current);
@@ -517,6 +518,7 @@ U32 ZSTD_insertBtAndGetAllMatches (
     const BYTE* const prefixStart = base + dictLimit;
     U32 const btLow = btMask >= current ? 0 : current - btMask;
     U32 const windowLow = ms->window.lowLimit;
+    U32 const matchLow = windowLow ? windowLow : 1;
     U32* smallerPtr = bt + 2*(current&btMask);
     U32* largerPtr  = bt + 2*(current&btMask) + 1;
     U32 matchEndIdx = current+8+1;   /* farthest referenced position of any match => detects repetitive patterns */
@@ -638,7 +640,7 @@ U32 ZSTD_insertBtAndGetAllMatches (
 
     hashTable[h] = current;   /* Update Hash Table */
 
-    while (nbCompares-- && (matchIndex > windowLow)) {
+    while (nbCompares-- && (matchIndex >= matchLow)) {
         U32* const nextPtr = bt + 2*(matchIndex & btMask);
         size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger);   /* guaranteed minimum nb of common bytes */
         const BYTE* match;