From cc1508f523f8f9d3038c4677c20214150daeb348 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Sat, 20 Jul 2024 09:22:44 -0700
Subject: [PATCH] more correct extDict detection

---
 lib/lz4hc.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index 588919bae..4d8c36a69 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -546,7 +546,7 @@ static int LZ4MID_compress (
     const BYTE* const dictStart = ctx->dictStart;
     const U32 dictIdx = ctx->lowLimit;
     const U32 gDictEndIndex = ctx->lowLimit;
-    const LZ4MID_searchIntoDict_f searchIntoDict = select_searchDict_function(ctx->dictCtx);
+    const LZ4MID_searchIntoDict_f searchIntoDict = (dict == usingDictCtxHc) ? select_searchDict_function(ctx->dictCtx) : NULL;
     unsigned matchLength;
     unsigned matchDistance;
 
@@ -651,14 +651,13 @@ static int LZ4MID_compress (
         /* no match found in prefix */
         if ( (dict == usingDictCtxHc)
           && (ipIndex - gDictEndIndex < LZ4_DISTANCE_MAX - 8) ) {
-            /* search a match in dictionary */
+            /* search a match into external dictionary */
             LZ4HC_match_t dMatch = searchIntoDict(ip, ipIndex,
                     matchlimit,
                     ctx->dictCtx, gDictEndIndex);
             if (dMatch.len >= MINMATCH) {
                 DEBUGLOG(7, "found Dictionary match (offset=%i)", dMatch.off);
-                ip += dMatch.back;
-                assert(ip >= anchor);
+                assert(dMatch.back == 0);
                 matchLength = (unsigned)dMatch.len;
                 matchDistance = (unsigned)dMatch.off;
                 goto _lz4mid_encode_sequence;