Method StartRead

CrySystem/RefReadStreamProxy.cpp:147–269

the interface for the actual stream returns true if the read has been started and no further attempts to do so are required returns false if couldn't start,and retry is required nMemQuota is the max number of bytes to allocate from the Engine's "Big Heap" for the piece of file that is read. Pass a big value to let it allocate as much as it wants.

// nMemQuota is the max number of bytes to allocate from the Engine's "Big Heap" for the piece of file
// that is read. Pass a big value to let it allocate as much as it wants.
bool CRefReadStreamProxy::StartRead (unsigned nMemQuota)
{
	if (m_bError || m_bFinished || m_bPending)
	{
		// Why this assert happened?
		//---------------------------
		// THe stream read was automatically initiated, while the stream is marked as
		// having been read, being read, or failed, i.e. it can't be restarted again.
		
		// This can generally happen when the read has been started, and immediately aborted,
		// while being put on hold. When there are enough IO resources to start reading it,
		// we detect that it's been already aborted and don't restart it.
		// This is the only known reason for that.
		assert (m_nIOError == ERROR_USER_ABORT);
		return true; // invalid call, no need to retry
	}

	if (!m_pStream->Activate())
	{
		OnFinishRead(ERROR_CANT_OPEN_FILE); // can't open file
		return true; // no need to retry
	}

	if (m_pStream->IsError())
	{
		OnFinishRead(ERROR_REFSTREAM_ERROR); // file is invalid
		return true;
	}

	if (m_Params.nOffset >= m_pStream->GetFileSize())
	{
		// offset out of range
		OnFinishRead(ERROR_OFFSET_OUT_OF_RANGE);
		return true;
	}

	if (m_Params.nSize > m_pStream->GetFileSize())
	{
		OnFinishRead(ERROR_SIZE_OUT_OF_RANGE);
		return true;
	}

	if (m_Params.nSize == 0)
	{
		// by default, we read the whole file
		m_Params.nSize = m_pStream->GetFileSize() - m_Params.nOffset;
	}
	else
	if (m_Params.nOffset + m_Params.nSize > m_pStream->GetFileSize())
	{
		// it's impossible to read the specified region of the file
		OnFinishRead(ERROR_REGION_OUT_OF_RANGE);
		return true;
	}

	if (!m_pBuffer)
	{
		if (nMemQuota < m_Params.nSize)