CI_Upload::do_xss_clean PHP Method

    public function do_xss_clean()
    {
        $file = $this->file_temp;
        if (filesize($file) == 0) {
            return FALSE;
        }
        if (memory_get_usage() && ($memory_limit = ini_get('memory_limit'))) {
            $memory_limit *= 1024 * 1024;
            // There was a bug/behavioural change in PHP 5.2, where numbers over one million get output
            // into scientific notation. number_format() ensures this number is an integer
            // http://bugs.php.net/bug.php?id=43053
            $memory_limit = number_format(ceil(filesize($file) + $memory_limit), 0, '.', '');
            ini_set('memory_limit', $memory_limit);
            // When an integer is used, the value is measured in bytes. - PHP.net
        }
        // If the file being uploaded is an image, then we should have no problem with XSS attacks (in theory), but
        // IE can be fooled into mime-type detecting a malformed image as an html file, thus executing an XSS attack on anyone
        // using IE who looks at the image. It does this by inspecting the first 255 bytes of an image. To get around this
        // CI will itself look at the first 255 bytes of an image to determine its relative safety. This can save a lot of
        // processor power and time if it is actually a clean image, as it will be in nearly all instances _except_ an
        // attempted XSS attack.
        if (function_exists('getimagesize') && @getimagesize($file) !== FALSE) {
            if (($file = @fopen($file, 'rb')) === FALSE) {
                return FALSE;
                // Couldn't open the file, return FALSE
            }
            $opening_bytes = fread($file, 256);
            fclose($file);
            // These are known to throw IE into mime-type detection chaos
            // <a, <body, <head, <html, <img, <plaintext, <pre, <script, <table, <title
            // title is basically just in SVG, but we filter it anyhow
            // if it's an image or no "triggers" detected in the first 256 bytes - we're good
            return !preg_match('/<(a|body|head|html|img|plaintext|pre|script|table|title)[\\s>]/i', $opening_bytes);
        }
        if (($data = @file_get_contents($file)) === FALSE) {
            return FALSE;
        }
        return $this->_CI->security->xss_clean($data, TRUE);
    }

 /**
  * do xss clean
  * this plugin makes sure that images do not get xss unless under very certain criteria
  * borrowed from CI 2.x mecurial repo
  *
  * @access	public
  * @return	bool
  */
 public function do_xss_clean()
 {
     $file = $this->upload_path . $this->file_name;
     if (filesize($file) == 0) {
         return FALSE;
     }
     if (function_exists('memory_get_usage') && memory_get_usage() && ini_get('memory_limit') != '') {
         $current = ini_get('memory_limit') * 1024 * 1024;
         $new_memory = number_format(ceil(filesize($file) + $current), 0, '.', '');
         ini_set('memory_limit', $new_memory);
         // When an integer is used, the value is measured in bytes. - PHP.net
     }
     if (function_exists('getimagesize') && @getimagesize($file) !== FALSE) {
         if (($file = @fopen($file, 'rb')) === FALSE) {
             return FALSE;
             // Couldn't open the file, return FALSE
         }
         $opening_bytes = fread($file, 256);
         fclose($file);
         if (!preg_match('/<(a|body|head|html|img|plaintext|pre|script|table|title)[\\s>]/i', $opening_bytes)) {
             return TRUE;
             // its an image, no "triggers" detected in the first 256 bytes, we're good
         }
     }
     //do default
     parent::do_xss_clean($types);
 }