root/LayoutTests/http/tests/download/resources/literal-utf-8.php

<?php
header("Content-Disposition: attachment; filename=SU\xd0\xa1\xd0\xa1\xd0\x95SS.txt");
header("Content-Type: text/plain; charset=koi8-r"); // Content-Type charset does not affect header charset.
?>

Test file content.