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added ZSTD_getFrameHeader_advanced()

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makes it possible to request frame header from a magicless frame
This commit is contained in:
Yann Collet 2018-03-29 17:51:08 -06:00
parent a6694838e1
commit e6e848bfe9
3 changed files with 23 additions and 9 deletions
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10
lib/decompress/zstd_decompress.c
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@ -305,13 +305,13 @@ size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize)
}
/** ZSTD_getFrameHeader_internal() :
/** ZSTD_getFrameHeader_advanced`() :
* decode Frame Header, or require larger `srcSize`.
* note : only works for formats ZSTD_f_zstd1 and ZSTD_f_zstd1_magicless
* @return : 0, `zfhPtr` is correctly filled,
* >0, `srcSize` is too small, value is wanted `srcSize` amount,
* or an error code, which can be tested using ZSTD_isError() */
static size_t ZSTD_getFrameHeader_internal(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format)
size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format)
{
const BYTE* ip = (const BYTE*)src;
size_t const minInputSize = ZSTD_startingInputLength(format);
@ -394,7 +394,7 @@ static size_t ZSTD_getFrameHeader_internal(ZSTD_frameHeader* zfhPtr, const void*
* or an error code, which can be tested using ZSTD_isError() */
size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize)
{
return ZSTD_getFrameHeader_internal(zfhPtr, src, srcSize, ZSTD_f_zstd1);
return ZSTD_getFrameHeader_advanced(zfhPtr, src, srcSize, ZSTD_f_zstd1);
}
@ -491,7 +491,7 @@ unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize)
* @return : 0 if success, or an error code, which can be tested using ZSTD_isError() */
static size_t ZSTD_decodeFrameHeader(ZSTD_DCtx* dctx, const void* src, size_t headerSize)
{
size_t const result = ZSTD_getFrameHeader_internal(&(dctx->fParams), src, headerSize, dctx->format);
size_t const result = ZSTD_getFrameHeader_advanced(&(dctx->fParams), src, headerSize, dctx->format);
if (ZSTD_isError(result)) return result; /* invalid header */
if (result>0) return ERROR(srcSize_wrong); /* headerSize too small */
if (dctx->fParams.dictID && (dctx->dictID != dctx->fParams.dictID))
@ -2767,7 +2767,7 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
return hint;
} }
#endif
{ size_t const hSize = ZSTD_getFrameHeader_internal(&zds->fParams, zds->headerBuffer, zds->lhSize, zds->format);
{ size_t const hSize = ZSTD_getFrameHeader_advanced(&zds->fParams, zds->headerBuffer, zds->lhSize, zds->format);
DEBUGLOG(5, "header size : %u", (U32)hSize);
if (ZSTD_isError(hSize)) {
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)

16
lib/zstd.h
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@ -1251,10 +1251,13 @@ ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams(
ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params);
/*=== Advanced parameters for decompression API ===*/
/* ==================================== */
/*=== Advanced decompression API ===*/
/* ==================================== */
/* The following parameters must be set after creating a ZSTD_DCtx* (or ZSTD_DStream*) object,
* but before starting decompression of a frame.
/* The following API works the same way as the advanced compression API :
* a context is created, parameters are pushed into it one by one,
* then the context can be used to decompress data using an interface similar to the straming API.
*/
/*! ZSTD_DCtx_loadDictionary() :
@ -1323,6 +1326,13 @@ ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowS
ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
/** ZSTD_getFrameHeader_advanced() :
* same as ZSTD_getFrameHeader(),
* with added capability to select a format (like ZSTD_f_zstd1_magicless) */
ZSTDLIB_API size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr,
const void* src, size_t srcSize, ZSTD_format_e format);
/*! ZSTD_decompress_generic() :
* Behave the same as ZSTD_decompressStream.
* Decompression parameters cannot be changed once decompression is started.

6
tests/fuzzer.c
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@ -1085,9 +1085,13 @@ static int basicUnitTests(U32 seed, double compressibility)
DISPLAYLEVEL(3, "OK : %s \n", ZSTD_getErrorName(decodeResult));
}
DISPLAYLEVEL(3, "test%3i : decompress with magic-less instruction : ", testNb++);
DISPLAYLEVEL(3, "test%3i : decompress of magic-less frame : ", testNb++);
ZSTD_DCtx_reset(dctx);
CHECK( ZSTD_DCtx_setFormat(dctx, ZSTD_f_zstd1_magicless) );
{ ZSTD_frameHeader zfh;
size_t const zfhrt = ZSTD_getFrameHeader_advanced(&zfh, compressedBuffer, cSize, ZSTD_f_zstd1_magicless);
if (zfhrt != 0) goto _output_error;
}
{ ZSTD_inBuffer in = { compressedBuffer, cSize, 0 };
ZSTD_outBuffer out = { decodedBuffer, CNBuffSize, 0 };
size_t const result = ZSTD_decompress_generic(dctx, &out, &in);