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stronger tests for zbuff decompression

dev
Yann Collet 2015-11-27 14:30:23 +01:00
parent 4a7bb12320
commit 800fa6c378
2 changed files with 14 additions and 8 deletions
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10
lib/zstd_static.h
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@ -126,17 +126,17 @@ size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, co
First operation is to retrieve frame parameters, using ZSTD_getFrameParams().
This function doesn't consume its input. It needs enough input data to properly decode the frame header.
The objective is to retrieve *params.windowlog, to know how much memory is required during decoding.
Result : 0 if successfull, it means the ZSTD_parameters structure has been filled.
The objective is to retrieve *params.windowlog, to know minimum amount of memory required during decoding.
Result : 0 when successful, it means the ZSTD_parameters structure has been filled.
>0 : means there is not enough data into src. Provides the expected size to successfully decode header.
errorCode, which can be tested using ZSTD_isError() (For example, if it's not a ZSTD header)
Then it's possible to start decompression.
Use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively.
ZSTD_nextSrcSizeToDecompress() tells how much bytes to provide as 'srcSize' to ZSTD_decompressContinue().
ZSTD_decompressContinue() will use previous data blocks during decompress.
They should be located contiguously prior to current block. Alternatively, a round buffer is possible.
Just make sure that the combined of current and accessible past blocks is a minimum of (1 << windowlog).
ZSTD_decompressContinue() requires this exact amount of bytes, or just fails.
ZSTD_decompressContinue() needs previous data blocks during decompression, up to (1 << windowlog).
They should preferably be located contiguously, prior to current block. Alternatively, a round buffer is also possible.
@result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst'.
It can be zero, which is not an error; it just means ZSTD_decompressContinue() has decoded some header.

12
programs/zbufftest.c
View File

@ -371,7 +371,10 @@ int fuzzerTests(U32 seed, U32 nbTests, unsigned startTest, double compressibilit
sampleSize = (size_t)1 << sampleSizeLog;
sampleSize += FUZ_rand(&lseed) & (sampleSize-1);
readSize = sampleSize;
genSize = dstBufferSize - totalGenSize;
sampleSizeLog = FUZ_rand(&lseed) % maxSampleLog;
sampleSize = (size_t)1 << sampleSizeLog;
sampleSize += FUZ_rand(&lseed) & (sampleSize-1);
genSize = MIN(sampleSize, dstBufferSize - totalGenSize);
errorCode = ZBUFF_decompressContinue(zd, dstBuffer+totalGenSize, &genSize, cBuffer+totalCSize, &readSize);
CHECK (ZBUFF_isError(errorCode), "decompression error : %s", ZBUFF_getErrorName(errorCode));
totalGenSize += genSize;
@ -405,13 +408,16 @@ int fuzzerTests(U32 seed, U32 nbTests, unsigned startTest, double compressibilit
ZBUFF_decompressInit(zd);
totalCSize = 0;
totalGenSize = 0;
while (totalCSize < cSize)
while ( (totalCSize < cSize) && (totalGenSize < dstBufferSize) )
{
sampleSizeLog = FUZ_rand(&lseed) % maxSampleLog;
sampleSize = (size_t)1 << sampleSizeLog;
sampleSize += FUZ_rand(&lseed) & (sampleSize-1);
readSize = sampleSize;
genSize = dstBufferSize - totalGenSize;
sampleSizeLog = FUZ_rand(&lseed) % maxSampleLog;
sampleSize = (size_t)1 << sampleSizeLog;
sampleSize += FUZ_rand(&lseed) & (sampleSize-1);
genSize = MIN(sampleSize, dstBufferSize - totalGenSize);
errorCode = ZBUFF_decompressContinue(zd, dstBuffer+totalGenSize, &genSize, cBuffer+totalCSize, &readSize);
if (ZBUFF_isError(errorCode)) break; /* error correctly detected */
totalGenSize += genSize;