def __isValidFilename(self, filename):
        """Determine whether filename is valid"""
        if filename and isinstance(filename, string_types):
            if re.match(r'^[\w\d\_\-\.]+$', filename, re.I):
                if self.__isValidTGZ(filename) or self.__isValidZIP(filename):
                    return True
        return False
Determine whether filename is valid