use strict;

use File::Spec::Functions 'catfile';
use IO::Dir;

sub _dircnts {
  my $dir = shift;
  my $do  = IO::Dir->new($dir) or die "Couldn't open '$dir': $!";
  return
    map catfile($dir, $_),
    grep !/^\.\.?$/, $do->read;
}

sub rec_readdir {
  my $dir  = shift;
  my @cnts = _dircnts $dir;

  my $iter; $iter = sub {
    my $f = pop @cnts;
    return unless defined $f;

    push @cnts, _dircnts $f
      and return &$iter
        if -d $f;

    return $f;
  };

  return $iter;
}

my $di = rec_readdir(shift);
while(my $file = &$di) {
  # do stuff here
}