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Don't Attach Empty Dict Contents

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In weird corner cases, they produce unexpected results...
This commit is contained in:
W. Felix Handte 2018-05-15 17:23:16 -04:00
parent 9c92223468
commit 582b7f85ed
1 changed files with 17 additions and 12 deletions
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29
lib/compress/zstd_compress.c
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@ -1227,20 +1227,25 @@ static size_t ZSTD_resetCCtx_usingCDict(ZSTD_CCtx* cctx,
}
if (attachDict) {
DEBUGLOG(4, "attaching dictionary into context");
cctx->blockState.matchState.dictMatchState = &cdict->matchState;
if (cdict->matchState.window.nextSrc - cdict->matchState.window.base == 0) {
/* don't even attach dictionaries with no contents */
DEBUGLOG(4, "skipping attaching empty dictionary");
} else {
DEBUGLOG(4, "attaching dictionary into context");
cctx->blockState.matchState.dictMatchState = &cdict->matchState;
/* prep working match state so dict matches never have negative indices
* when they are translated to the working context's index space. */
if (cctx->blockState.matchState.window.dictLimit <
(U32)(cdict->matchState.window.nextSrc - cdict->matchState.window.base)) {
cctx->blockState.matchState.window.nextSrc =
cctx->blockState.matchState.window.base +
( cdict->matchState.window.nextSrc
- cdict->matchState.window.base);
ZSTD_window_clear(&cctx->blockState.matchState.window);
/* prep working match state so dict matches never have negative indices
* when they are translated to the working context's index space. */
if (cctx->blockState.matchState.window.dictLimit <
(U32)(cdict->matchState.window.nextSrc - cdict->matchState.window.base)) {
cctx->blockState.matchState.window.nextSrc =
cctx->blockState.matchState.window.base +
( cdict->matchState.window.nextSrc
- cdict->matchState.window.base);
ZSTD_window_clear(&cctx->blockState.matchState.window);
}
cctx->blockState.matchState.loadedDictEnd = cctx->blockState.matchState.window.dictLimit;
}
cctx->blockState.matchState.loadedDictEnd = cctx->blockState.matchState.window.dictLimit;
} else {
DEBUGLOG(4, "copying dictionary into context");
/* copy tables */