4.3BSD/usr/ingres/source/libq/IIpb_read.c

# include	<ingres.h>
# include	"IIglobals.h"
# include	<sccs.h>

SCCSID(@(#)IIpb_read.c	8.1	12/31/84)


/*
**  IIPB_READ -- read a pipe block
**
**	This routine reads a pipe block into *ppb.  It also handles
**	all the low level protocol: RESET blocks, SYNC blocks, META
**	blocks, blocks intended for another process, etc.
**
**	When this routine returns, it returns with a block intended
**	for this process, which must be a REGULAR block, a RESPONSE
**	block, or an ERROR block.
**
**	Parameters:
**		ppb -- a pointer to the area which wants the block.
**
**	Returns:
**		none
**
**	Side Effects:
**		ppb is set to the named block.
**		Virtually any amount of stuff can happen, depending
**			on what is coming through the pipe.
**
**	Trace Flags:
**		12.4 - 12.9
*/


IIpb_read(ppb)
register pb_t	*ppb;
{
	register int	type;
	register int	from;

	/*
	**  Top Loop.
	**	Hang waiting for a normal block.  Other blocks are
	**		handled inside the loop.
	**	We multiplex 'from' in here temporarily.
	*/

	for (;;)
	{
		from = IIpb_rphys(ppb, IIinput);

		if (from != PB_IOSIZE)
			IIsyserr("pb_read: read error (%d)", from);

		/* set up buffer pointers, etc. */
		ppb->pb_xptr = ppb->pb_data;
		ppb->pb_nleft = ppb->pb_nused;
		type = ppb->pb_type;
		from = ppb->pb_from;

		/* do sync block processing */
		if (type == PB_SYNC)
		{
			IISyncs[from]--;
			continue;
		}

		/* see if we are ignoring from this process */
		if (IISyncs[from] > 0)
			continue;

		/*
		**  Block type dispatching.
		**	Regular, response, and error blocks return.
		**	Meta blocks are handled by calling other
		**		routines.
		*/

		switch (type)
		{
		  case PB_REG:
		  case PB_RESP:
		  case PB_ERR:
			/* handled by readinput() */
			return;

		  /* insert more meta handling before this line */

		  default:
			IIsyserr("pb_read: type %d", type);
		}
	}
}