// read one block if possible
BOOL CBlockBuffer::ReadBlock(void *pv, SLONG &slSize)
{
// must not be inside block reading
ASSERT(bb_slBlockSizeRead==0);
// read header of next block in incoming buffer
struct BlockHeader bh;
SLONG slbhSize;
slbhSize = ReadBytes(&bh, sizeof(bh));
// if the header information is not in buffer
if (slbhSize < sizeof(bh)) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
// if the block has not yet been received
if (QueryReadBytes() < bh.bh_slSize) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
// if there is too much data for the receiving memory space
if (bh.bh_slSize > slSize) {
// unwind
UnreadBytes(slbhSize);
// mark how much space we would need
slSize = bh.bh_slSize;
// nothing to receive
ASSERT(FALSE); // this shouldn't happen
return FALSE;
}
// if using stats
if (bb_pbbsStats!=NULL) {
// if block could not have been received yet, due to time limits
if (bh.bh_tvFinalTime>_pTimer->GetHighPrecisionTimer()) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
}
// read the block
slSize = ReadBytes(pv, bh.bh_slSize);
ASSERT(slSize == bh.bh_slSize);
// received
return TRUE;
}
// read one block from buffer to stream
BOOL CBlockBuffer::ReadBlockToStream(CTStream &strm)
{
// must not be inside block reading
ASSERT(bb_slBlockSizeRead==0);
// read header of next block in incoming buffer
struct BlockHeader bh;
SLONG slbhSize;
slbhSize = ReadBytes(&bh, sizeof(bh));
// if the header information is not in buffer
if (slbhSize < sizeof(bh)) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
// if the block has not yet been received
if (QueryReadBytes() < bh.bh_slSize) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
// if using stats
if (bb_pbbsStats!=NULL) {
// if block could not have been received yet, due to time limits
if (bh.bh_tvFinalTime>_pTimer->GetHighPrecisionTimer()) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
}
// read from buffer to destination buffer
try {
SLONG slSize = ReadBytesToStream(strm, bh.bh_slSize);
ASSERT(slSize == bh.bh_slSize);
} catch (char *strError) {
ASSERT(FALSE);
CPrintF(TRANS("Buffer error reading to stream: %s\n"), strError);
return FALSE;
}
return TRUE;
}
// peek sizes of next block
void CBlockBuffer::PeekBlockSize(SLONG &slExpectedSize, SLONG &slReceivedSoFar)
{
// if inside block reading
if(bb_slBlockSizeRead>0) {
// no information available
slExpectedSize = 0;
slReceivedSoFar = 0;
// if not inside block reading
} else {
// read header of next block in incoming buffer
struct BlockHeader bh;
SLONG slbhSize;
slbhSize = ReadBytes(&bh, sizeof(bh));
// unwind
UnreadBytes(slbhSize);
// if the header information is not in buffer
if (slbhSize < sizeof(bh)) {
// no information available
slExpectedSize = 0;
slReceivedSoFar = 0;
// if the header information is present
} else {
// total size is size of block
slExpectedSize = bh.bh_slSize;
// received so far is how much is really present
slReceivedSoFar = QueryReadBytes()-sizeof(struct BlockHeader);
}
}
}
// fill buffer to contain at least iNumChars bytes past cursor
bool CxdsBuffer::Fill(u32 iNumChars)
{
// short-circuit unnecessary fills
if(m_iUnreadBytes >= iNumChars)
return true;
// move existing data (if any) to beginning of buffer
Sync();
if(!ExpandToFit(iNumChars))
return false;
// read additional data into buffer (retries if not enough is read and end-of-file is not reached)
int nchrs = 0;
while(nchrs >= 0 && m_iUnreadBytes < iNumChars)
{
nchrs = XDS_READ(m_hFile, (void*)(m_cursor + m_iUnreadBytes), m_iBufSize - UnreadBytes());
if(nchrs > 0)
{
AddUnreadBytes(nchrs);
}
}
return (m_iUnreadBytes >= iNumChars);
}
// unread raw block data
void CBlockBuffer::UnreadRawBlock(SLONG slSize)
{
bb_slBlockSizeRead+=slSize;
UnreadBytes(slSize);
}
// read raw block data
SLONG CBlockBuffer::ReadRawBlock(void *pv, SLONG slSize)
{
// if inside block reading
if(bb_slBlockSizeRead>0) {
// clamp size to prevent reading across real blocks
slSize = Min(slSize, bb_slBlockSizeRead);
// read the raw block
SLONG slResult = ReadBytes(pv, slSize);
ASSERT(slResult==slSize);
// decrement block size counter
bb_slBlockSizeRead-=slResult;
// must not underflow
ASSERT(bb_slBlockSizeRead>=0);
return slResult;
// if not inside block reading
} else {
// read header of next block in incoming buffer
struct BlockHeader bh;
SLONG slbhSize;
slbhSize = ReadBytes(&bh, sizeof(bh));
// if the header information is not in buffer
if (slbhSize < sizeof(bh)) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
// if the block has not yet been received
if (QueryReadBytes() < bh.bh_slSize) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
// if using stats
if (bb_pbbsStats!=NULL) {
// if block could not have been received yet, due to time limits
if (bh.bh_tvFinalTime>_pTimer->GetHighPrecisionTimer()) {
// unwind
UnreadBytes(slbhSize);
// nothing to receive
return FALSE;
}
}
// remember block size counter
bb_slBlockSizeRead = bh.bh_slSize+sizeof(struct BlockHeader);
// unwind header
UnreadBytes(slbhSize);
// clamp size to prevent reading across real blocks
slSize = Min(slSize, bb_slBlockSizeRead);
// read the raw block with header
SLONG slResult = ReadBytes(pv, slSize);
ASSERT(slResult==slSize);
// decrement block size counter
bb_slBlockSizeRead-=slResult;
// must not underflow
ASSERT(bb_slBlockSizeRead>=0);
return slResult;
}
}
// unread one block
void CBlockBuffer::UnreadBlock(SLONG slSize)
{
UnreadBytes(slSize+sizeof(struct BlockHeader));
}
