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package IPC::Open2;
require 5.000;
require Exporter;
use Carp;
@ISA = qw(Exporter);
@EXPORT = qw(open2);
# &open2: tom christiansen, <tchrist@convex.com>
#
# usage: $pid = open2('rdr', 'wtr', 'some cmd and args');
# or $pid = open2('rdr', 'wtr', 'some', 'cmd', 'and', 'args');
#
# spawn the given $cmd and connect $rdr for
# reading and $wtr for writing. return pid
# of child, or 0 on failure.
#
# WARNING: this is dangerous, as you may block forever
# unless you are very careful.
#
# $wtr is left unbuffered.
#
# abort program if
# rdr or wtr are null
# pipe or fork or exec fails
$fh = 'FHOPEN000'; # package static in case called more than once
sub open2 {
local($kidpid);
local($dad_rdr, $dad_wtr, @cmd) = @_;
$dad_rdr ne '' || croak "open2: rdr should not be null";
$dad_wtr ne '' || croak "open2: wtr should not be null";
# force unqualified filehandles into callers' package
local($package) = caller;
$dad_rdr =~ s/^[^']+$/$package'$&/;
$dad_wtr =~ s/^[^']+$/$package'$&/;
local($kid_rdr) = ++$fh;
local($kid_wtr) = ++$fh;
pipe($dad_rdr, $kid_wtr) || croak "open2: pipe 1 failed: $!";
pipe($kid_rdr, $dad_wtr) || croak "open2: pipe 2 failed: $!";
if (($kidpid = fork) < 0) {
croak "open2: fork failed: $!";
} elsif ($kidpid == 0) {
close $dad_rdr; close $dad_wtr;
open(STDIN, "<&$kid_rdr");
open(STDOUT, ">&$kid_wtr");
warn "execing @cmd\n" if $debug;
exec @cmd;
croak "open2: exec of @cmd failed";
}
close $kid_rdr; close $kid_wtr;
select((select($dad_wtr), $| = 1)[0]); # unbuffer pipe
$kidpid;
}
1; # so require is happy
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