admin and preg_match('/\A<[a-z][^>]*>/', $input)) {
return $input; # allow html input as is if privileged
}
$html = preg_replace(
["/\r\n?/", "/ +\n/", "/\n/", '/\b_(\w+)_\b/'],
["\n", "
", "\n", '$1' ],
htmlspecialchars($input)
);
return "
$html
";
}