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refactored ZSTD_estimateDStreamSize()

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now uses windowSize as argument.
Also : created ZSTD_estimateDStreamSize_fromFrame()
This commit is contained in:
Yann Collet
2017-06-26 17:44:26 -07:00
parent 09ae03a570
commit dde10b23fe
5 changed files with 62 additions and 26 deletions
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lib/compress/zstd_compress.c
+5
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@@ -3594,6 +3594,11 @@ ZSTD_CStream* ZSTD_createCStream(void)
return ZSTD_createCStream_advanced(ZSTD_defaultCMem);
}
ZSTD_CStream* ZSTD_initStaticCStream(void *workspace, size_t workspaceSize)
{
return ZSTD_initStaticCCtx(workspace, workspaceSize);
}
ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem)
{ /* CStream and CCtx are now same object */
return ZSTD_createCCtx_advanced(customMem);
lib/decompress/zstd_decompress.c
+15 -2
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@@ -2143,6 +2143,11 @@ ZSTD_DStream* ZSTD_createDStream(void)
return ZSTD_createDStream_advanced(ZSTD_defaultCMem);
}
ZSTD_DStream* ZSTD_initStaticDStream(void *workspace, size_t workspaceSize)
{
return ZSTD_initStaticDCtx(workspace, workspaceSize);
}
ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem)
{
return ZSTD_createDCtx_advanced(customMem);
@@ -2214,15 +2219,23 @@ size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds)
return ZSTD_sizeof_DCtx(zds);
}
size_t ZSTD_estimateDStreamSize(ZSTD_frameHeader fHeader)
size_t ZSTD_estimateDStreamSize(size_t windowSize)
{
size_t const windowSize = fHeader.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);
return sizeof(ZSTD_DStream) + ZSTD_estimateDCtxSize() + inBuffSize + outBuffSize;
}
ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize)
{
ZSTD_frameHeader fh;
size_t const err = ZSTD_getFrameHeader(&fh, src, srcSize);
if (ZSTD_isError(err)) return err;
if (err>0) return ERROR(srcSize_wrong);
return ZSTD_estimateDStreamSize(fh.windowSize);
}
/* ***** Decompression ***** */
lib/zstd.h
+20 -11
View File
@@ -412,7 +412,7 @@ typedef struct {
typedef struct {
unsigned long long frameContentSize;
unsigned windowSize;
size_t windowSize;
unsigned dictID;
unsigned checksumFlag;
} ZSTD_frameHeader;
@@ -509,12 +509,17 @@ ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void);
* ZSTD_estimateCStreamSize() will consider src size to be arbitrarily "large".
* If srcSize is known to be small, ZSTD_estimateCStreamSize_advanced() can provide a tighter estimation.
* ZSTD_estimateCStreamSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
* Note : CStream estimation is only correct for single-threaded compression.
* ZSTD_DStream memory budget depends on window Size.
* This information can be passed manually, using ZSTD_estimateDStreamSize,
* or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame();
* Note : if streaming is init with function ZSTD_init?Stream_usingDict(),
* an internal ?Dict will be created, which size is not estimated here.
* an internal ?Dict will be created, which additional size is not estimated here.
* In this case, get total size by adding ZSTD_estimate?DictSize */
ZSTDLIB_API size_t ZSTD_estimateCStreamSize(int compressionLevel);
ZSTDLIB_API size_t ZSTD_estimateCStreamSize_advanced(ZSTD_compressionParameters cParams);
ZSTDLIB_API size_t ZSTD_estimateDStreamSize(ZSTD_frameHeader fHeader);
ZSTDLIB_API size_t ZSTD_estimateDStreamSize(size_t windowSize);
ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize);
/*! ZSTD_estimate?DictSize() :
* ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict().
@@ -717,6 +722,7 @@ ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize);
/*===== Advanced Streaming compression functions =====*/
ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem);
ZSTDLIB_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */
ZSTDLIB_API size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); /**< pledgedSrcSize must be correct, a size of 0 means unknown. for a frame size of 0 use initCStream_advanced */
ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); /**< creates of an internal CDict (incompatible with static CCtx), except if dict == NULL or dictSize < 8, in which case no dict is used. */
ZSTDLIB_API size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize,
@@ -737,6 +743,7 @@ ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledg
/*===== Advanced Streaming decompression functions =====*/
typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e;
ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem);
ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */
ZSTDLIB_API size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue);
ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); /**< note: a dict will not be used if dict == NULL or dictSize < 8 */
ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); /**< note : ddict will just be referenced, and must outlive decompression session */
@@ -803,16 +810,18 @@ ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapaci
A ZSTD_DCtx object can be re-used multiple times.
First typical operation is to retrieve frame parameters, using ZSTD_getFrameHeader().
It fills a ZSTD_frameParams structure which provide important information to correctly decode the frame,
such as the minimum rolling buffer size to allocate to decompress data (`windowSize`),
and the dictionary ID used.
It fills a ZSTD_frameHeader structure with important information to correctly decode the frame,
such as minimum rolling buffer size to allocate to decompress data (`windowSize`),
and the dictionary ID in use.
(Note : content size is optional, it may not be present. 0 means : content size unknown).
Note that these values could be wrong, either because of data malformation, or because an attacker is spoofing deliberate false information.
As a consequence, check that values remain within valid application range, especially `windowSize`, before allocation.
Each application can set its own limit, depending on local restrictions. For extended interoperability, it is recommended to support at least 8 MB.
Frame parameters are extracted from the beginning of the compressed frame.
Data fragment must be large enough to ensure successful decoding, typically `ZSTD_frameHeaderSize_max` bytes.
@result : 0 : successful decoding, the `ZSTD_frameParams` structure is correctly filled.
Each application can set its own limit, depending on local restrictions.
For extended interoperability, it is recommended to support windowSize of at least 8 MB.
Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough.
Data fragment must be large enough to ensure successful decoding.
`ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough.
@result : 0 : successful decoding, the `ZSTD_frameHeader` structure is correctly filled.
>0 : `srcSize` is too small, please provide at least @result bytes on next attempt.
errorCode, which can be tested using ZSTD_isError().
@@ -857,7 +866,7 @@ ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapaci
*/
/*===== Buffer-less streaming decompression functions =====*/
ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input, see details below */
ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input */
ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx);
ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
ZSTDLIB_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);