ddidderr/zstd-rs
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ZSTD_decodingBufferSize_min()

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supporting function for bufferless streaming API (ZSTD_decompressContinue())
makes it possible to correctly size a round buffer for decoding using this API.

also : added field blockSizeMax within ZSTD_frameHeader,
as it's a necessary information to know when to restart at beginning of decoding buffer.
This commit is contained in:
Yann Collet
2017-09-09 01:03:29 -07:00
parent 3128e03be6
commit 058ed2ad33
5 changed files with 113 additions and 69 deletions
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lib/decompress/zstd_decompress.c
+16 -5
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@@ -297,7 +297,6 @@ size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t src
memset(zfhPtr, 0, sizeof(*zfhPtr));
zfhPtr->frameContentSize = MEM_readLE32((const char *)src + 4);
zfhPtr->frameType = ZSTD_skippableFrame;
zfhPtr->windowSize = 0;
return 0;
}
return ERROR(prefix_unknown);
@@ -350,6 +349,7 @@ size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t src
zfhPtr->frameType = ZSTD_frame;
zfhPtr->frameContentSize = frameContentSize;
zfhPtr->windowSize = windowSize;
zfhPtr->blockSizeMax = (unsigned) MIN(windowSize, ZSTD_BLOCKSIZE_MAX);
zfhPtr->dictID = dictID;
zfhPtr->checksumFlag = checksumFlag;
}
@@ -2117,7 +2117,7 @@ unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict)
* ZSTD_getFrameHeader(), which will provide a more precise error code. */
unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize)
{
ZSTD_frameHeader zfp = { 0, 0, ZSTD_frame, 0, 0, 0 };
ZSTD_frameHeader zfp = { 0, 0, 0, ZSTD_frame, 0, 0, 0 };
size_t const hError = ZSTD_getFrameHeader(&zfp, src, srcSize);
if (ZSTD_isError(hError)) return 0;
return zfp.dictID;
@@ -2224,17 +2224,28 @@ size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds)
return ZSTD_sizeof_DCtx(zds);
}
size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize)
{
size_t const blockSize = (size_t) MIN(windowSize, ZSTD_BLOCKSIZE_MAX);
unsigned long long const neededRBSize = windowSize + blockSize + (WILDCOPY_OVERLENGTH * 2);
unsigned long long const neededSize = MIN(frameContentSize, neededRBSize);
size_t const minRBSize = (size_t) neededSize;
if ((unsigned long long)minRBSize != neededSize) return ERROR(frameParameter_windowTooLarge);
return minRBSize;
}
size_t ZSTD_estimateDStreamSize(size_t windowSize)
{
size_t const blockSize = MIN(windowSize, ZSTD_BLOCKSIZE_MAX);
size_t const inBuffSize = blockSize; /* no block can be larger */
size_t const outBuffSize = windowSize + blockSize + (WILDCOPY_OVERLENGTH * 2);
//size_t const outBuffSize = windowSize + blockSize + (WILDCOPY_OVERLENGTH * 2);
size_t const outBuffSize = ZSTD_decodingBufferSize_min(windowSize, ZSTD_CONTENTSIZE_UNKNOWN);
return ZSTD_estimateDCtxSize() + inBuffSize + outBuffSize;
}
ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize)
{
U32 const windowSizeMax = 1U << ZSTD_WINDOWLOG_MAX;
U32 const windowSizeMax = 1U << ZSTD_WINDOWLOG_MAX; /* note : should be user-selectable */
ZSTD_frameHeader zfh;
size_t const err = ZSTD_getFrameHeader(&zfh, src, srcSize);
if (ZSTD_isError(err)) return err;
@@ -2350,7 +2361,7 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
if (zds->fParams.windowSize > zds->maxWindowSize) return ERROR(frameParameter_windowTooLarge);
/* Adapt buffer sizes to frame header instructions */
{ size_t const blockSize = (size_t)(MIN(zds->fParams.windowSize, ZSTD_BLOCKSIZE_MAX));
{ size_t const blockSize = zds->fParams.blockSizeMax;
size_t const neededOutSize = (size_t)(zds->fParams.windowSize + blockSize + WILDCOPY_OVERLENGTH * 2);
zds->blockSize = blockSize;
if ((zds->inBuffSize < blockSize) || (zds->outBuffSize < neededOutSize)) {