my $chunk_size = $cnf->{chunk_size} || 1024;
    my $bytes_in = $cnf->{bytes_in} || 0;
    my $bytes_out= $cnf->{bytes_out} || undef;

    my $pos = $bytes_in;
    seek($fh,$bytes_in,0);
    while ( read( $fh, my $buffer, $chunk_size ) ) {
        $pos += $chunk_size; # alt.: += length($buffer)

        if( defined($bytes_out) && $pos > $bytes_out){
              print bytes::substr($buffer, 0, ($chunk_size - ($pos - $bytes_out)) );  # make last chunk shorter
              last;
        }elsif( defined($bytes_out) && $pos == $bytes_out){
              print $buffer;
              last;
        }else{
              print $buffer;
        }
   }