csv diff

$file1_name = basename( $_FILES['file1']['name'] );
    $file1_name = substr(md5(rand()), 0, 5). "-" .$file1_name;
    $file2_name = basename( $_FILES['file2']['name'] );
    $file2_name = substr(md5(rand()), 0, 5). "-" .$file2_name;

    if (move_uploaded_file($_FILES['file1']['tmp_name'], $file1_name) && move_uploaded_file($_FILES['file2']['tmp_name'], $file2_name) ) {

        $file1 = file($file1_name, FILE_IGNORE_NEW_LINES);
        $file2 = file($file2_name, FILE_IGNORE_NEW_LINES);

        sort($file1);
        sort($file2);

        $diff = array_diff($file2, $file1);
        array_unshift($diff, $_POST['csv_cols']);
        $output = substr(md5(rand()), 0, 5). "-output.csv";
        file_put_contents($output, implode(PHP_EOL, $diff));

        unlink($file1_name);
        unlink($file2_name);

        header('Content-Description: Download ' . $output);
        header('Content-Type: application/force-download');
        header("Content-Type: application/download");
        header("Content-Length: " . filesize($output));
        header("Content-disposition: attachment; filename=\"" . basename($output) . "\"");
        readfile($output);
        unlink($output);
        exit;
    } else {
        echo "An unknown error occured";
    }