#!/usr/bin/perl
use strict;
use warnings;
use Fatal qw( close );    # monitored (auto-)close

close STDIN;
close STDOUT;

my %handle_for;
@handle_for{qw( message_in message_out )} = pipe_from(0);
@handle_for{qw( header_in  header_out )}  = pipe_from(4);
@handle_for{qw( body_in    body_out )}    = pipe_from(6);

print {*STDERR} "$_ has descriptor ", fileno($handle_for{$_}), "\n"
  for sort { fileno($handle_for{$a}) <=> fileno($handle_for{$b}) }
  keys %handle_for;

sub pipe_from {    # Assuming consecutive numbers are ok
   my ($n) = @_;

   my @fakes;
   while (1) {
      open my $fh, '<', '/dev/zero' or die "open(): $!";
      push @fakes, $fh;
      last if fileno($fh) == $n;
      die "file descriptor $n not available" if fileno($fh) > $n;
   } ## end while (1)
   close pop @fakes; # Free last used descriptor, that's equal to $n

   pipe my ($r, $w);
   die "pipe(): $!" unless defined $r;

   close $_ for @fakes;
   return ($r, $w);
} ## end sub pipe_from

__END__

poletti@PolettiX:~/sviluppo/perl$ perl pipes.pl
message_in has descriptor 0
message_out has descriptor 1
header_in has descriptor 4
header_out has descriptor 5
body_in has descriptor 6
body_out has descriptor 7