Kill a hung child process

Question

My Perl script runs an external program (which takes a single command-line parameter) and processes its output. Originally, I was doing this:

my @result = `p         


        

Answer 1

This is the best I could do. Any ideas on how to avoid the use of a temporary file on Windows would be appreciated.

#!/usr/bin/perl

use strict;
use warnings;
use File::Temp;
use Win32::Process qw(STILL_ACTIVE NORMAL_PRIORITY_CLASS);

my $pid;
my $timeout = 10;
my $prog = "prog arg";
my @output;

if ($^O eq "MSWin32")
{
    my $exitcode;
    my $fh = File::Temp->new ();
    my $output_file = $fh->filename;
    close ($fh);
    open (OLDOUT, ">&STDOUT");
    open (STDOUT, ">$output_file" ) || die ("Unable to redirect STDOUT to $output_file.\n");
    Win32::Process::Create ($pid, $^X, $prog, 1, NORMAL_PRIORITY_CLASS, '.') or die Win32::FormatMessage (Win32::GetLastError ());
    for (1 .. $timeout)
    {
        $pid->GetExitCode ($exitcode);
        last if ($exitcode != STILL_ACTIVE);
        sleep 1;
    }
    $pid->GetExitCode ($exitcode);
    $pid->Kill (0) or die "Cannot kill '$pid'" if ($exitcode == STILL_ACTIVE);
    close (STDOUT);
    open (STDOUT, ">&OLDOUT");
    close (OLDOUT);
    open (FILE, "<$output_file");
    push @output, $_ while ();
    close (FILE);
}
else
{
    $pid = open my $proc, "-|", $prog;
    exec ($^X, "-e", "sleep 1, kill (0, $pid) || exit for 1..$timeout; kill -9, $pid") unless (fork ());
    push @output, $_ while (<$proc>);
    close ($proc);
}
print "Output:\n";
print @output;