[UCLA-LUG] Async I/O notification on FIFOs possible??

[Kai-Min Sung]

I can't seem to get asynchronous I/O notification on a FIFO working on
Linux.  I've heard some rumors that it isn't implemented yet in Linux, but
it seems like such a trivial thing to do.  Can someone confirm that
it does/doesn't work?

Here's the code I used to test. No matter what I try writing to the FIFO,
there is no SIGIO being generated.

-Kai
kaimin@cs.ucla.edu


--- code snippit ---
void sigio(int signal)
{
	printf("received signal %d\n", signal);
	fflush(NULL);
}

int main()
{
	int fd;

	/* Register SIGIO handler */
	signal(SIGIO, sigio);

	/* Create the FIFO */
	mkfifo("/tmp/FIFO", 0777);

	/* Open the FIFO */
	fd = open("/tmp/FIFO", O_RDONLY | O_NONBLOCK);

	/* Set async flag */
	fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_ASYNC);

	/* Set SETSIG flag to receive SIGIO signal */
	fcntl(fd, F_SETSIG, 0);

	/* Wait for SIGIO signal...*/
	pause();

	return 0;
}
--- code snippit ---