Function pqPutMsgStart

src/interfaces/libpq/fe-misc.c:501–530

* pqPutMsgStart: begin construction of a message to the server * * msg_type is the message type byte, or 0 for a message without type byte * (only startup messages have no type byte) * * Returns 0 on success, EOF on error * * The idea here is that we construct the message in conn->outBuffer, * beginning just past any data already in outBuffer (ie, at * outBuffer+outCount). We enlarge the

 * the data collected so far.
 */
int
pqPutMsgStart(char msg_type, PGconn *conn)
{
	int			lenPos;
	int			endPos;

	/* allow room for message type byte */
	if (msg_type)
		endPos = conn->outCount + 1;
	else
		endPos = conn->outCount;

	/* do we want a length word? */
	lenPos = endPos;
	/* allow room for message length */
	endPos += 4;

	/* make sure there is room for message header */
	if (pqCheckOutBufferSpace(endPos, conn))
		return EOF;
	/* okay, save the message type byte if any */
	if (msg_type)
		conn->outBuffer[conn->outCount] = msg_type;
	/* set up the message pointers */
	conn->outMsgStart = lenPos;
	conn->outMsgEnd = endPos;
	/* length word, if needed, will be filled in by pqPutMsgEnd */

	return 0;
}

/*
 * pqPutMsgBytes: add bytes to a partially-constructed message