Method fetch

src/remote/client/interface.cpp:4837–5249

bool ResultSet::fetch(CheckStatusWrapper* status, void* buffer, P_FETCH operation, int position)
{
/**************************************
 *
 *	d s q l _ f e t c h
 *
 **************************************
 *
 * Functional description
 *	Fetch next record from a dynamic SQL cursor.
 *
 **************************************/

	reset(status);

	// Check and validate handles, etc.

	if (delayedFormat || !stmt)
	{
		(Arg::Gds(isc_dsql_cursor_err) << Arg::Gds(isc_bad_req_handle)).raise();
	}

	Rsr* const statement = stmt->getStatement();
	CHECK_HANDLE(statement, isc_bad_req_handle);

	Rdb* const rdb = statement->rsr_rdb;
	CHECK_HANDLE(rdb, isc_bad_db_handle);

	rem_port* const port = rdb->rdb_port;

	// Scrolling is not available in older protocols
	if (operation != fetch_next && port->port_protocol < PROTOCOL_FETCH_SCROLL)
		unsupported();

	// Whether we're fetching relatively to the current position
	const bool relative =
		(operation == fetch_next || operation == fetch_prior || operation == fetch_relative);

	BlrFromMessage outBlr(outputFormat, stmt->getDialect(), port->port_protocol);
	unsigned int blr_length = outBlr.getLength();
	const UCHAR* blr = outBlr.getBytes();
	const unsigned int msg_length = outBlr.getMsgLength();
	UCHAR* msg = static_cast<UCHAR*>(buffer);

	// Validate data length

	CHECK_LENGTH(port, blr_length);
	CHECK_LENGTH(port, msg_length);

	RefMutexGuard portGuard(*port->port_sync, FB_FUNCTION);

	if (!statement->rsr_flags.test(Rsr::FETCHED))
	{
		// On first fetch, clear the end-of-stream flag & reset the message buffers

		statement->raiseException();

		statement->rsr_flags.clear(Rsr::STREAM_END | Rsr::PAST_END | Rsr::STREAM_ERR);