ddidderr/zstd-rs
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Merge pull request #1390 from facebook/nullAsOutput

Browse Source 
support decompressing an empty frame into NULL
This commit is contained in:
Yann Collet
2018-10-26 14:43:16 -07:00
committed by GitHub
parent e26126caca 806a5c84e4
commit 7d4960a5e8
2 changed files with 73 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/decompress/zstd_decompress.c
+28 -21
View File
@@ -404,9 +404,9 @@ unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize)
}
/** ZSTD_getDecompressedSize() :
* compatible with legacy mode
* @return : decompressed size if known, 0 otherwise
note : 0 can mean any of the following :
* compatible with legacy mode
* @return : decompressed size if known, 0 otherwise
note : 0 can mean any of the following :
- frame content is empty
- decompressed size field is not present in frame header
- frame header unknown / not supported
@@ -420,8 +420,8 @@ unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize)
/** ZSTD_decodeFrameHeader() :
* `headerSize` must be the size provided by ZSTD_frameHeaderSize().
* @return : 0 if success, or an error code, which can be tested using ZSTD_isError() */
* `headerSize` must be the size provided by ZSTD_frameHeaderSize().
* @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_advanced(&(dctx->fParams), src, headerSize, dctx->format);
@@ -439,7 +439,7 @@ static size_t ZSTD_decodeFrameHeader(ZSTD_DCtx* dctx, const void* src, size_t he
***************************************************************/
/*! ZSTD_getcBlockSize() :
* Provides the size of compressed block from block header `src` */
* Provides the size of compressed block from block header `src`. */
size_t ZSTD_getcBlockSize(const void* src, size_t srcSize,
blockProperties_t* bpPtr)
{
@@ -459,9 +459,10 @@ size_t ZSTD_getcBlockSize(const void* src, size_t srcSize,
static size_t ZSTD_copyRawBlock(void* dst, size_t dstCapacity,
const void* src, size_t srcSize)
{
if (dst==NULL) return ERROR(dstSize_tooSmall);
DEBUGLOG(5, "ZSTD_copyRawBlock");
if (dst == NULL) dstCapacity = 0; /* better safe than sorry */
if (srcSize > dstCapacity) return ERROR(dstSize_tooSmall);
memcpy(dst, src, srcSize);
if (dst) memcpy(dst, src, srcSize);
return srcSize;
}
@@ -1761,7 +1762,9 @@ size_t ZSTD_findFrameCompressedSize(const void *src, size_t srcSize)
}
/*! ZSTD_decompressFrame() :
* @dctx must be properly initialized */
* @dctx must be properly initialized
* will update *srcPtr and *srcSizePtr,
* to make *srcPtr progress by one frame. */
static size_t ZSTD_decompressFrame(ZSTD_DCtx* dctx,
void* dst, size_t dstCapacity,
const void** srcPtr, size_t *srcSizePtr)
@@ -1770,31 +1773,33 @@ static size_t ZSTD_decompressFrame(ZSTD_DCtx* dctx,
BYTE* const ostart = (BYTE* const)dst;
BYTE* const oend = ostart + dstCapacity;
BYTE* op = ostart;
size_t remainingSize = *srcSizePtr;
size_t remainingSrcSize = *srcSizePtr;
DEBUGLOG(4, "ZSTD_decompressFrame (srcSize:%i)", (int)*srcSizePtr);
/* check */
if (remainingSize < ZSTD_frameHeaderSize_min+ZSTD_blockHeaderSize)
if (remainingSrcSize < ZSTD_frameHeaderSize_min+ZSTD_blockHeaderSize)
return ERROR(srcSize_wrong);
/* Frame Header */
{ size_t const frameHeaderSize = ZSTD_frameHeaderSize(ip, ZSTD_frameHeaderSize_prefix);
if (ZSTD_isError(frameHeaderSize)) return frameHeaderSize;
if (remainingSize < frameHeaderSize+ZSTD_blockHeaderSize)
if (remainingSrcSize < frameHeaderSize+ZSTD_blockHeaderSize)
return ERROR(srcSize_wrong);
CHECK_F( ZSTD_decodeFrameHeader(dctx, ip, frameHeaderSize) );
ip += frameHeaderSize; remainingSize -= frameHeaderSize;
ip += frameHeaderSize; remainingSrcSize -= frameHeaderSize;
}
/* Loop on each block */
while (1) {
size_t decodedSize;
blockProperties_t blockProperties;
size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSize, &blockProperties);
size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSrcSize, &blockProperties);
if (ZSTD_isError(cBlockSize)) return cBlockSize;
ip += ZSTD_blockHeaderSize;
remainingSize -= ZSTD_blockHeaderSize;
if (cBlockSize > remainingSize) return ERROR(srcSize_wrong);
remainingSrcSize -= ZSTD_blockHeaderSize;
if (cBlockSize > remainingSrcSize) return ERROR(srcSize_wrong);
switch(blockProperties.blockType)
{
@@ -1817,7 +1822,7 @@ static size_t ZSTD_decompressFrame(ZSTD_DCtx* dctx,
XXH64_update(&dctx->xxhState, op, decodedSize);
op += decodedSize;
ip += cBlockSize;
remainingSize -= cBlockSize;
remainingSrcSize -= cBlockSize;
if (blockProperties.lastBlock) break;
}
@@ -1828,16 +1833,16 @@ static size_t ZSTD_decompressFrame(ZSTD_DCtx* dctx,
if (dctx->fParams.checksumFlag) { /* Frame content checksum verification */
U32 const checkCalc = (U32)XXH64_digest(&dctx->xxhState);
U32 checkRead;
if (remainingSize<4) return ERROR(checksum_wrong);
if (remainingSrcSize<4) return ERROR(checksum_wrong);
checkRead = MEM_readLE32(ip);
if (checkRead != checkCalc) return ERROR(checksum_wrong);
ip += 4;
remainingSize -= 4;
remainingSrcSize -= 4;
}
/* Allow caller to get size read */
*srcPtr = ip;
*srcSizePtr = remainingSize;
*srcSizePtr = remainingSrcSize;
return op-ostart;
}
@@ -1869,7 +1874,9 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
if (dctx->staticSize) return ERROR(memory_allocation);
decodedSize = ZSTD_decompressLegacy(dst, dstCapacity, src, frameSize, dict, dictSize);
if (ZSTD_isError(decodedSize)) return decodedSize;
assert(decodedSize <=- dstCapacity);
dst = (BYTE*)dst + decodedSize;
dstCapacity -= decodedSize;
@@ -1922,7 +1929,7 @@ static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
return ERROR(srcSize_wrong);
}
if (ZSTD_isError(res)) return res;
/* no need to bound check, ZSTD_decompressFrame already has */
assert(res <= dstCapacity);
dst = (BYTE*)dst + res;
dstCapacity -= res;
}