{
    local $/ = '====';
    open local(*FILE1), '<', shift or die $!;


##</code><code>##

    local $_ = <FILE1>;
    while (<FILE1>) {
        my @header_data = header_extract($_);
        my $data = <FILE1>;   # second read
        my @data = data_extract($data);
        # ...
    }
    close DATA1 or die $!;
    redo if @ARGV;
}