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lz4frame : removed some intermediate stage from LZ4F_decompress()

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ensure some strange jump cases are not possible
(they were already not possible, but static analyzer couldn't understand it).
This commit is contained in:
Yann Collet 2018-01-14 00:15:07 -08:00
parent cdd0c685e0
commit 5e7780d2d8
1 changed files with 6 additions and 16 deletions
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22
lib/lz4frame.c
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@ -895,8 +895,7 @@ typedef enum {
dstage_getBlockHeader, dstage_storeBlockHeader,
dstage_copyDirect, dstage_getBlockChecksum,
dstage_getCBlock, dstage_storeCBlock,
dstage_decodeCBlock, dstage_decodeCBlock_intoDst,
dstage_decodeCBlock_intoTmp, dstage_flushOut,
dstage_flushOut,
dstage_getSuffix, dstage_storeSuffix,
dstage_getSFrameSize, dstage_storeSFrameSize,
dstage_skipSkippable
@ -1423,9 +1422,8 @@ size_t LZ4F_decompress(LZ4F_dctx* dctx,
/* input large enough to read full block directly */
selectedIn = srcPtr;
srcPtr += dctx->tmpInTarget;
dctx->dStage = dstage_decodeCBlock;
break;
if (0) /* jump over next block */
case dstage_storeCBlock:
{ size_t const wantedData = dctx->tmpInTarget - dctx->tmpInSize;
size_t const inputLeft = (size_t)(srcEnd-srcPtr);
@ -1439,12 +1437,9 @@ size_t LZ4F_decompress(LZ4F_dctx* dctx,
break;
}
selectedIn = dctx->tmpIn;
dctx->dStage = dstage_decodeCBlock;
}
/* fall-through */
/* At this stage, input is large enough to decode a block */
case dstage_decodeCBlock:
/* At this stage, input is large enough to decode a block */
if (dctx->frameInfo.blockChecksumFlag) {
dctx->tmpInTarget -= 4;
assert(selectedIn != NULL); /* selectedIn is defined at this stage (either srcPtr, or dctx->tmpIn) */
@ -1453,14 +1448,10 @@ size_t LZ4F_decompress(LZ4F_dctx* dctx,
if (readBlockCrc != calcBlockCrc)
return err0r(LZ4F_ERROR_blockChecksum_invalid);
} }
if ((size_t)(dstEnd-dstPtr) < dctx->maxBlockSize) /* not enough place into dst : decode into tmpOut */
dctx->dStage = dstage_decodeCBlock_intoTmp;
else
dctx->dStage = dstage_decodeCBlock_intoDst;
break;
case dstage_decodeCBlock_intoDst:
{ int const decodedSize = LZ4_decompress_safe_usingDict(
if ((size_t)(dstEnd-dstPtr) >= dctx->maxBlockSize) {
/* enough capacity in `dst` to decompress directly there */
int const decodedSize = LZ4_decompress_safe_usingDict(
(const char*)selectedIn, (char*)dstPtr,
(int)dctx->tmpInTarget, (int)dctx->maxBlockSize,
(const char*)dctx->dict, (int)dctx->dictSize);
@ -1479,7 +1470,6 @@ size_t LZ4F_decompress(LZ4F_dctx* dctx,
break;
}
case dstage_decodeCBlock_intoTmp:
/* not enough place into dst : decode into tmpOut */
/* ensure enough place for tmpOut */
if (dctx->frameInfo.blockMode == LZ4F_blockLinked) {