BaiduUtils::detectMimeType PHP Method

    private static function detectMimeType($filename)
    {
        // finfo extension from PECL available
        if (function_exists('finfo_open')) {
            if (!isset(self::$fileinfoDb)) {
                self::$fileinfoDb = finfo_open(FILEINFO_MIME);
            }
            if (self::$fileinfoDb) {
                $info = finfo_file(self::$fileinfoDb, $filename);
            }
        }
        // (deprecated) mime_content_type function available
        if (empty($info) && function_exists('mime_content_type')) {
            $info = mime_content_type($filename);
        }
        return empty($info) ? 'application/octet-stream' : $info;
    }