From: W. Felix Handte <w@felixhandte.com>
Date: Wed, 26 Aug 2020 22:33:44 +0000 (-0400)
Subject: Permit Matching Against Lowest Valid Position
X-Git-Tag: v1.4.7~81^2~7
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d332f57897394426afb4270de85aecac2a2fce3e;p=thirdparty%2Fzstd.git

Permit Matching Against Lowest Valid Position

This comparison was previously faulty: the lowest valid position is itself
valid, and we should therefore be allowed to match against it.
---

diff --git a/lib/compress/zstd_lazy.c b/lib/compress/zstd_lazy.c
index 684e7e56e..15df6125e 100644
--- a/lib/compress/zstd_lazy.c
+++ b/lib/compress/zstd_lazy.c
@@ -544,7 +544,7 @@ size_t ZSTD_HcFindBestMatch_generic (
     /* HC4 match finder */
     matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls);
 
-    for ( ; (matchIndex>lowLimit) & (nbAttempts>0) ; nbAttempts--) {
+    for ( ; (matchIndex>=lowLimit) & (nbAttempts>0) ; nbAttempts--) {
         size_t currentMl=0;
         if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) {
             const BYTE* const match = base + matchIndex;
@@ -649,7 +649,7 @@ size_t ZSTD_HcFindBestMatch_generic (
 
         matchIndex = dms->hashTable[ZSTD_hashPtr(ip, dms->cParams.hashLog, mls)];
 
-        for ( ; (matchIndex>dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--) {
+        for ( ; (matchIndex>=dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--) {
             size_t currentMl=0;
             const BYTE* const match = dmsBase + matchIndex;
             assert(match+4 <= dmsEnd);