functions.php

<?php 
function sanitize($str) {
    $output = '';
    $str=htmlspecialchars($str, ENT_QUOTES, 'UTF-8');
    $str = str_split($str);
    for($i=0;$i<count($str);$i++) {
        $chrNum = ord($str[$i]);
        $chr = $str[$i];
        if($chrNum === 226) {
            if(isset($str[$i+1]) && ord($str[$i+1]) === 128) {
                if(isset($str[$i+2]) && ord($str[$i+2]) === 168) {
                    $output .= '\u2028';
                    $i += 2;
                    continue;
                }
                if(isset($str[$i+2]) && ord($str[$i+2]) === 169) {
                    $output .= '\u2029';
                    $i += 2;
                    continue;
                }
            }
        }
        switch($chr) {
            case "'":
            case '"':
            case "\n";
            case "\r";
            case "&";
            case "\\";
            case "<":
            case ">":
                $output .= sprintf("\\u%04x", $chrNum);
            break;
            default:
                $output .= $str[$i];
            break;
    }
    }
    return $output;
}
?>