Need help with SIGALRM/ualarm

[Paul Turner]

Hello,

I'm trying to do some animation on an RS6000 (a 320 w
AIX 3.1 plus the 3001 update) and I'm having problems
with the alarm call. The following code fragment performs
exactly as I expected on a Sun w SunOS 4.0 but fails on the
RS6000 with a single call to the alarm signal handler followed
by the termination of the program. like:

% testalarm
r              <- initialize the alarm handler
Called         <- from the handler
Alarm call     <- from AIX !!?? and the program terminates

What I believe to be the correct behavior is a continuous
stream of 'Called' lines - as set below, every 100 milliseconds.
This is what happens on our Suns. 

Any clues? Is there a different way of doing this using
some other method? I can't use X/Xt calls to XtAddTimeOut
(which is what I'm trying to replace). Is it a bug or am I
doing something wrong? Any help would be appreciated.

Thanks,

--Paul
Paul J. Turner
pturner at ese.ogi.edu

------------ cut here ----------

#include <stdio.h>
#include <sys/signal.h>

void animate()
{
    printf("Called\n");
}

/*
 * set a SIGALRM handler, the ualarm
 * call sets the first call after 1 sec and calls
 * are made every 100 milliseconds thereafter
 */
setrun()
{
    signal(SIGALRM, animate);
    ualarm(1000000, 100000);
}

setstop()
{
    signal(SIGALRM, SIG_IGN);
}

main()
{
    char s[256];
    while (1) {
	gets(s);
	switch (s[0]) {
	case 'q':
	    exit(0);
	break;
	case 'r':
	    setrun();
	break;
	case 's':
	    setstop();
	break;
	}
	s[0] = 0;
    }
}