Asynchronous Network Transfers

Although an application can use poll() to check periodically for the arrival of data or to wait for the receipt of data on an endpoint, receiving asynchronous notification when data arrives might be necessary. Use ioctl() with the I_SETSIG command to request that a SIGPOLL signal be sent to the process upon receipt of data at the endpoint. Applications should check for the possibility of multiple messages causing a single signal.

In the following example, protocol is the name of the application-chosen transport protocol.

#include <sys/types.h>
#include <tiuser.h>
#include <signal.h>
#include <stropts.h>

int              fd;
struct t_bind    *bind;
void             sigpoll(int);

	fd = t_open(protocol, O_RDWR, (struct t_info *) NULL);

	bind = (struct t_bind *) t_alloc(fd, T_BIND, T_ADDR);
	...     /* set up binding address */
	t_bind(fd, bind, bin

	/* make endpoint non-blocking */
	fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);

	/* establish signal handler for SIGPOLL */
	signal(SIGPOLL, sigpoll);

	/* request SIGPOLL signal when receive data is available */
	ioctl(fd, I_SETSIG, S_INPUT | S_HIPRI);

	...

void sigpoll(int sig)
{
	int                  flags;
	struct t_unitdata    ud;

	for (;;) {
		... /* initialize ud */
		if (t_rcvudata(fd, &ud, &flags) < 0) {
			if (t_errno == TNODATA)
				break;  /* no more messages */
			... /* process other error conditions */
	}
	... /* process message in ud */
}