/*--------------------------------------------------------------------------
 Arrgh.  Red Hat Linux 4.2 always seems to restart read() if interrupted
 by a signal.  RH5.0 can be coaxed into making the read() return when
 interrupted by a signal, thank goodness.

 http://www.dejanews.com/getdoc.xp?AN=313705083 has some relevant discussion.
 dank@alumni.caltech.edu
--------------------------------------------------------------------------*/
#include <unistd.h>
#include <signal.h>
#include <stdio.h>

static void
alarm_handler( sig )
int sig;
{
	printf("Got signal\n");
}

main()
{
	int i;

	/* Four different ways of setting up the signal handler. */
#if 0
	(void) signal( SIGALRM, alarm_handler );	/* doesn't interrupt fgets() :-( */
#endif
#if 1
	(void) signal( SIGALRM, alarm_handler );
	siginterrupt(SIGALRM, 1);			/* works ok in RH5.0, not 4.2 */
#endif
#if 0
	(void) sysv_signal( SIGALRM, alarm_handler );	/* Doesn't link in RH4.2 or 5.0 */
#endif
#if 0
	struct sigaction newact;
	memset(&newact, 0, sizeof(newact));
	newact.sa_handler = alarm_handler;
	sigemptyset(&newact.sa_mask);
	sigaddset(&newact.sa_mask, SIGALRM);
	sigaction(SIGALRM,  &newact, NULL);		/* works ok in RH5.0, not 4.2 */
#endif

	printf("Want to see 'Calling alarm...' then 'Got Signal' printed out three times \n\
in three seconds.  If it just sits for longer than a few seconds, \n\
the fgets() didn't get interrupted, and the test is a failure.\n");
	for (i=0; i<3; i++) {
		char buf[128];
		printf("Calling alarm...\n");
		alarm(1);
		gets(buf);	/* Want this to return when alarm goes off */
	}
	if (i == 3)
		printf("Test passed - alarm() successfully used to set a timeout on gets()\n");
	else
		printf("Test failed - signal handler didn't stay active after first firing\n");
}