#!/usr/bin/perl
use common::sense;
use Data::Dumper;

use Fcntl;
use Socket;
use IO::Pty;

my @cmd = qw(/usr/bin/gpg --enable-special-filenames --verify -);
#my @cmd = (qw(perl -n -E), 'BEGIN {open my $fh, "<&=3" or die "aaa: $!" } chomp; syswrite \*STDOUT, "### $_\n"');

pipe my $parent_data, my $child_data or die "pipe: $!";

socketpair my $parent_in,  my $child_in,  AF_UNIX, SOCK_STREAM, 0 or die "socketpair: $!";
socketpair my $parent_out, my $child_out, AF_UNIX, SOCK_STREAM, 0 or die "socketpair: $!";
pipe my $rsync, my $wsync or die "pipe: $!";

my $pid = fork;
die "fork: $!" unless defined $pid;

unless ($pid) {
    $child_in->close;
    $child_out->close;
    $child_data->close;
    $rsync->close;

    $wsync->autoflush(1);


    $parent_out->autoflush(1);

    open STDIN,  '<&', $parent_in or die "redirect STDIN: $!";
    open STDOUT, '>&', $parent_out or die "redirect STDOUT $!";
    open STDERR, '>&', $parent_out or die "redirect STDERR $!";

    syswrite $wsync, "\n";
    $wsync->close;

    fcntl($parent_data, F_SETFD, 0) or die "fcntl: $!";
    push @cmd, '-&' . fileno $parent_data;

    exec {$cmd[0]} $cmd[0], @cmd[1..@cmd - 1];
    die "exec: $!";
}


$parent_in->close;
$parent_out->close;
$parent_data->close;
$wsync->close;

{ sysread $rsync, my $c, 1 or die "sync read: $!" }
$rsync->close;

my $sign = do { local $/; open my $fh, '<', 'sign' or die $!; <$fh> };

$child_in->autoflush(1);

syswrite $child_in, $sign;
$child_in->close;

syswrite $child_data, '1;2';
$child_data->close;

say "after write";

while (<$child_out>) {
    chomp;
    say '=> ', $_;
}

waitpid $pid, 0;
say "$?" if $?;