in lib/legacy/zstd_v07.c [4396:4533]
size_t ZBUFFv07_decompressContinue(ZBUFFv07_DCtx* zbd,
void* dst, size_t* dstCapacityPtr,
const void* src, size_t* srcSizePtr)
{
const char* const istart = (const char*)src;
const char* const iend = istart + *srcSizePtr;
const char* ip = istart;
char* const ostart = (char*)dst;
char* const oend = ostart + *dstCapacityPtr;
char* op = ostart;
U32 notDone = 1;
while (notDone) {
switch(zbd->stage)
{
case ZBUFFds_init :
return ERROR(init_missing);
case ZBUFFds_loadHeader :
{ size_t const hSize = ZSTDv07_getFrameParams(&(zbd->fParams), zbd->headerBuffer, zbd->lhSize);
if (ZSTDv07_isError(hSize)) return hSize;
if (hSize != 0) {
size_t const toLoad = hSize - zbd->lhSize; /* if hSize!=0, hSize > zbd->lhSize */
if (toLoad > (size_t)(iend-ip)) { /* not enough input to load full header */
memcpy(zbd->headerBuffer + zbd->lhSize, ip, iend-ip);
zbd->lhSize += iend-ip;
*dstCapacityPtr = 0;
return (hSize - zbd->lhSize) + ZSTDv07_blockHeaderSize; /* remaining header bytes + next block header */
}
memcpy(zbd->headerBuffer + zbd->lhSize, ip, toLoad); zbd->lhSize = hSize; ip += toLoad;
break;
} }
/* Consume header */
{ size_t const h1Size = ZSTDv07_nextSrcSizeToDecompress(zbd->zd); /* == ZSTDv07_frameHeaderSize_min */
size_t const h1Result = ZSTDv07_decompressContinue(zbd->zd, NULL, 0, zbd->headerBuffer, h1Size);
if (ZSTDv07_isError(h1Result)) return h1Result;
if (h1Size < zbd->lhSize) { /* long header */
size_t const h2Size = ZSTDv07_nextSrcSizeToDecompress(zbd->zd);
size_t const h2Result = ZSTDv07_decompressContinue(zbd->zd, NULL, 0, zbd->headerBuffer+h1Size, h2Size);
if (ZSTDv07_isError(h2Result)) return h2Result;
} }
zbd->fParams.windowSize = MAX(zbd->fParams.windowSize, 1U << ZSTDv07_WINDOWLOG_ABSOLUTEMIN);
/* Frame header instruct buffer sizes */
{ size_t const blockSize = MIN(zbd->fParams.windowSize, ZSTDv07_BLOCKSIZE_ABSOLUTEMAX);
zbd->blockSize = blockSize;
if (zbd->inBuffSize < blockSize) {
zbd->customMem.customFree(zbd->customMem.opaque, zbd->inBuff);
zbd->inBuffSize = blockSize;
zbd->inBuff = (char*)zbd->customMem.customAlloc(zbd->customMem.opaque, blockSize);
if (zbd->inBuff == NULL) return ERROR(memory_allocation);
}
{ size_t const neededOutSize = zbd->fParams.windowSize + blockSize + WILDCOPY_OVERLENGTH * 2;
if (zbd->outBuffSize < neededOutSize) {
zbd->customMem.customFree(zbd->customMem.opaque, zbd->outBuff);
zbd->outBuffSize = neededOutSize;
zbd->outBuff = (char*)zbd->customMem.customAlloc(zbd->customMem.opaque, neededOutSize);
if (zbd->outBuff == NULL) return ERROR(memory_allocation);
} } }
zbd->stage = ZBUFFds_read;
/* pass-through */
/* fall-through */
case ZBUFFds_read:
{ size_t const neededInSize = ZSTDv07_nextSrcSizeToDecompress(zbd->zd);
if (neededInSize==0) { /* end of frame */
zbd->stage = ZBUFFds_init;
notDone = 0;
break;
}
if ((size_t)(iend-ip) >= neededInSize) { /* decode directly from src */
const int isSkipFrame = ZSTDv07_isSkipFrame(zbd->zd);
size_t const decodedSize = ZSTDv07_decompressContinue(zbd->zd,
zbd->outBuff + zbd->outStart, (isSkipFrame ? 0 : zbd->outBuffSize - zbd->outStart),
ip, neededInSize);
if (ZSTDv07_isError(decodedSize)) return decodedSize;
ip += neededInSize;
if (!decodedSize && !isSkipFrame) break; /* this was just a header */
zbd->outEnd = zbd->outStart + decodedSize;
zbd->stage = ZBUFFds_flush;
break;
}
if (ip==iend) { notDone = 0; break; } /* no more input */
zbd->stage = ZBUFFds_load;
}
/* fall-through */
case ZBUFFds_load:
{ size_t const neededInSize = ZSTDv07_nextSrcSizeToDecompress(zbd->zd);
size_t const toLoad = neededInSize - zbd->inPos; /* should always be <= remaining space within inBuff */
size_t loadedSize;
if (toLoad > zbd->inBuffSize - zbd->inPos) return ERROR(corruption_detected); /* should never happen */
loadedSize = ZBUFFv07_limitCopy(zbd->inBuff + zbd->inPos, toLoad, ip, iend-ip);
ip += loadedSize;
zbd->inPos += loadedSize;
if (loadedSize < toLoad) { notDone = 0; break; } /* not enough input, wait for more */
/* decode loaded input */
{ const int isSkipFrame = ZSTDv07_isSkipFrame(zbd->zd);
size_t const decodedSize = ZSTDv07_decompressContinue(zbd->zd,
zbd->outBuff + zbd->outStart, zbd->outBuffSize - zbd->outStart,
zbd->inBuff, neededInSize);
if (ZSTDv07_isError(decodedSize)) return decodedSize;
zbd->inPos = 0; /* input is consumed */
if (!decodedSize && !isSkipFrame) { zbd->stage = ZBUFFds_read; break; } /* this was just a header */
zbd->outEnd = zbd->outStart + decodedSize;
zbd->stage = ZBUFFds_flush;
/* break; */
/* pass-through */
}
}
/* fall-through */
case ZBUFFds_flush:
{ size_t const toFlushSize = zbd->outEnd - zbd->outStart;
size_t const flushedSize = ZBUFFv07_limitCopy(op, oend-op, zbd->outBuff + zbd->outStart, toFlushSize);
op += flushedSize;
zbd->outStart += flushedSize;
if (flushedSize == toFlushSize) {
zbd->stage = ZBUFFds_read;
if (zbd->outStart + zbd->blockSize > zbd->outBuffSize)
zbd->outStart = zbd->outEnd = 0;
break;
}
/* cannot flush everything */
notDone = 0;
break;
}
default: return ERROR(GENERIC); /* impossible */
} }
/* result */
*srcSizePtr = ip-istart;
*dstCapacityPtr = op-ostart;
{ size_t nextSrcSizeHint = ZSTDv07_nextSrcSizeToDecompress(zbd->zd);
nextSrcSizeHint -= zbd->inPos; /* already loaded*/
return nextSrcSizeHint;
}
}