From: W. Felix Handte <w@felixhandte.com>
Date: Wed, 23 May 2018 20:00:17 +0000 (-0400)
Subject: Assert that Dict and Current Window are Adjacent in Index Space
X-Git-Tag: v1.3.5~3^2~44^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d9c7e67125d95d751e934870fdf611fbe0995934;p=thirdparty%2Fzstd.git

Assert that Dict and Current Window are Adjacent in Index Space
---

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 105cea44b..00f3e789d 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -2210,6 +2210,11 @@ static size_t ZSTD_compressBlock_internal(ZSTD_CCtx* zc,
     ZSTD_resetSeqStore(&(zc->seqStore));
     ms->opt.symbolCosts = &zc->blockState.prevCBlock->entropy;   /* required for optimal parser to read stats from dictionary */
 
+    /* a gap between an attached dict and the current window is not safe,
+     * they must remain adjacent, and when that stops being the case, the dict
+     * must be unset */
+    assert(ms->dictMatchState == NULL || ms->loadedDictEnd == ms->window.dictLimit);
+
     /* limited update after a very long match */
     {   const BYTE* const base = ms->window.base;
         const BYTE* const istart = (const BYTE*)src;
diff --git a/lib/compress/zstd_fast.c b/lib/compress/zstd_fast.c
index bf962a175..3bac2bddd 100644
--- a/lib/compress/zstd_fast.c
+++ b/lib/compress/zstd_fast.c
@@ -72,7 +72,7 @@ size_t ZSTD_compressBlock_fast_generic(
     const BYTE* const dictEnd      = dictMode == ZSTD_dictMatchState ?
                                      dms->window.nextSrc : NULL;
     const U32 dictIndexDelta       = dictMode == ZSTD_dictMatchState ?
-                                     ms->loadedDictEnd - (U32)(dictEnd - dictBase) :
+                                     prefixLowestIndex - (U32)(dictEnd - dictBase) :
                                      0;
     const U32 dictAndPrefixLength  = (U32)(ip - prefixLowest + dictEnd - dictLowest);