Function getAnotherTuple

src/interfaces/libpq/fe-protocol3.c:913–1023

* parseInput subroutine to read a 'D' (row data) message. * We fill rowbuf with column pointers and then call the row processor. * Returns: 0 if processed message successfully, EOF to suspend parsing * (the latter case is not actually used currently). */

 * (the latter case is not actually used currently).
 */
static int
getAnotherTuple(PGconn *conn, int msgLength)
{
	PGresult   *result = conn->result;
	int			nfields = result->numAttributes;
	const char *errmsg;
	PGdataValue *rowbuf;
	int			tupnfields;		/* # fields from tuple */
	int			vlen;			/* length of the current field value */
	int			i;

	/* Get the field count and make sure it's what we expect */
	if (pqGetInt(&tupnfields, 2, conn))
	{
		/* We should not run out of data here, so complain */
		errmsg = libpq_gettext("insufficient data in \"D\" message");
		goto advance_and_error;
	}

	if (tupnfields != nfields)
	{
		errmsg = libpq_gettext("unexpected field count in \"D\" message");
		goto advance_and_error;
	}

	/* Resize row buffer if needed */
	rowbuf = conn->rowBuf;
	if (nfields > conn->rowBufLen)
	{
		rowbuf = (PGdataValue *) realloc(rowbuf,
										 nfields * sizeof(PGdataValue));
		if (!rowbuf)
		{
			errmsg = NULL;		/* means "out of memory", see below */
			goto advance_and_error;
		}
		conn->rowBuf = rowbuf;
		conn->rowBufLen = nfields;
	}

	/* Scan the fields */
	for (i = 0; i < nfields; i++)
	{
		/* get the value length */
		if (pqGetInt(&vlen, 4, conn))
		{
			/* We should not run out of data here, so complain */
			errmsg = libpq_gettext("insufficient data in \"D\" message");
			goto advance_and_error;
		}
		rowbuf[i].len = vlen;

		/*
		 * rowbuf[i].value always points to the next address in the data
		 * buffer even if the value is NULL.  This allows row processors to
		 * estimate data sizes more easily.
		 */
		rowbuf[i].value = conn->inBuffer + conn->inCursor;