Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!sun-barr!newstop!texsun!convex!convex.com!tchrist
From: tchrist@convex.com (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: itimers
Message-ID: <5334@convex.convex.com>
Date: 11 Feb 90 18:25:11 GMT
Sender: news@convex.com
Reply-To: tchrist@convex.com (Tom Christiansen)
Organization: Convex Computer Corp, Richardson, TX
Lines: 153

I've worked up [sg]etitimer routines and an alarm(), but when 
I run my test case, this is the output I get:

    timeleft is 0, 0
    setting alarms at Sun Feb 11 12:18:04 CDT 1990
    Bad free() ignored at itimers/ttimer line 61.
    alarm: setitimer failed: Invalid argument at itimers/ttimer line 79.
    alarm had 0 secs left

This means the getitimer was happy, but then there was some
internal glitch and then the setitimer failed.

Larry, is the failed system related to the bad free(), or am 
I miscalling the system call someway as it would have me believe?
Also, ttimer hasn't got 79 lines, why does it say it does?

Extract the sharchive and run itimers/ttimer to reproduce.  You'll
need syscall.h, sys/time.h, and ctime.pl to run this.  The first
two are generated with makelib, and the last has been passed around 
in this group before.  I'll supply it if you don't have it.

thanks

#!/bin/sh
#    This is a shell archive.
#    Run the following text with /bin/sh to extract.

echo mkdir itimers
mkdir itimers
echo cd itimers
cd itimers
echo x timers.pl
sed -e 's/^X//' << \EOFMARK > timers.pl
X#
X# timer manipulation functions
X#
X#	getitimer
X#	setitimer
X#	alarm
X
Xdo 'source.pl' unless defined &source;
Xdo source('syscall.h') unless defined &SYS_setitimer;
Xdo source('sys/time.h') unless defined &ITIMER_REAL;
X
X#
X# careful: implentation dependent!
X#
X$itimer_t = 'L2';  # itimers consist of two longs
X$sizeof{'itimer'} = '8' unless defined $sizeof{'itimer'};
X
X###########################################################################
X# itimer conversion function; this one goes both ways
Xsub itimer {
X    wantarray ? unpack($itimer_t, $_[0])
X	      : pack($itimer_t, $_[0], $_[1]); 
X} 
X
X
X###########################################################################
Xsub setitimer {
X    local($which) = shift;
X
X    die "setitimer: input itimer not length ".$sizeof{'itimer'} 
X	unless length($_[0]) == $sizeof{'itimer'};
X
X    $_[1] = &itimer(0,0);
X    !syscall(&SYS_setitimer, $which, $_[0], $_[1]);
X} 
X
X###########################################################################
Xsub getitimer {
X    local($which) = shift;
X
X    $_[0] = &itimer(0,0);
X
X    !syscall(&SYS_getitimer, $which, $_[0]);
X} 
X
X###########################################################################
X# 
X# alarm; send me a SIGALRM in this many seconds
X#
Xsub alarm {
X    local($ticks) = @_;
X    local($itimer,$otimer);
X    local($secs, $usecs);
X
X    $otimer = &itimer(0,0);
X    $itimer = &itimer($ticks,0);
X
X    do setitimer(&ITIMER_REAL, $itimer, $otimer) || warn "alarm: setitimer failed: $!";
X
X    ($secs, $usecs) = &itimer($otimer);
X    return $secs;
X} 
X
EOFMARK
echo x ttimer
sed -e 's/^X//' << \EOFMARK > ttimer
X#!/usr/bin/perl
X
Xdo 'source.pl' || die "can't do source.pl";
X
Xdo source('timers.pl');
Xdo source('ctime.pl');
X
X$| = 1;
X
X$SIG{'ALRM'} = 'bingo';
X
Xsub bingo {
X    print "i was alarmed at time ", &ctime(time);
X    $hit++;
X} 
X
Xdo timeleft();
X
Xprint "setting alarms at ", &ctime(time);
X
Xdo alarm(7);
X
Xprintf "alarm had %d secs left\n", &alarm(3);
X
Xdo { } until $hit; 
X
Xprint "escaped at ", &ctime(time);
X
Xsub timeleft {
X    &getitimer(&ITIMER_REAL, $timeleft) || die "can't getitimer: $!";
X    printf "timeleft is %d, %d\n", &itimer($timeleft);
X}
EOFMARK
echo chmod +x ttimer
chmod +x ttimer
echo x source.pl
sed -e 's/^X//' << \EOFMARK > source.pl
X
X###########################################################################
Xsub source {
X    local($file) = @_;
X    local($return) = 0;
X
X    $return = do $file;
X    die "couldn't do \"$file\": $!" unless defined $return;
X    die "couldn't parse \"$file\": $@" if $@;
X    die "couldn't run \"$file\"" unless $return;
X} 
X
X###########################################################################
X
X1;
EOFMARK
exit 0