Path: utzoo!utgpu!watserv1!ria!ria.ccs.uwo.ca!clipper
From: clipper@chan.csd.uwo.ca (Khun Yee Fung)
Newsgroups: comp.lang.perl
Subject: Re: How to do alarm()?
Message-ID: <CLIPPER.90Oct31104736@chan.csd.uwo.ca>
Date: 31 Oct 90 10:47:36 GMT
References: <1990Oct31.041758.15623@uvaarpa.Virginia.EDU>
Sender: news@ria.ccs.uwo.ca
Organization: University of Western Ontario, Department of Computer Science
Lines: 40
In-reply-to: telxon!ping!gorpong@uunet.uu.net's message of 31 Oct 90 04:17:58 GMT

Thank you very much for the code to do alarm(). I tried both of them
and they both worked. Thank you Larry for adding it in the next patch.

I also found the error I committed when I used the various codes
written by others and myself, all using syscall().  I used a return
statement in the interrupt subroutine. It produced a Segmentation
fault error. If I used a return statement in the code written by
<worley@compass.uucp>, the same error would be produced (on my machine
anyway).  I wonder why. Anybody has any idea? Just curious.

#! /usr2/new/bin/perl

# Interval to re-read the information, in seconds
$interval = 1;

# Set the timer to go off in 1 second, and every $interval seconds
# thereafter.  Call &get_info when it goes off.
require 'syscall.h';
$SIG{'ALRM'} = 'get_info';
$value = pack('LLLL', $interval, 0, 1, 0);
syscall(&SYS_setitimer, 0, $value, 0);
while (1) {
}

sub get_info {
  print "get_info\n";
# Have a return here will produce a Segmentation fault error on a 
# sun 3/50 running SunOS 4.03
#  return;
}

--
----
In Real life: Khun Yee Fung    clipper@csd.uwo.ca (Internet) 
Alternative: 4054_3267@UWOVAX.BITNET
UUCP: ...!{ihnp4|decvax|seismo}!{watmath|utzoo}!ria!csd!clipper
Department of Computer Science
Middlesex College
The University of Western Ontario
London, Ontario, N6A 5B7  CANADA