def _read_str(file_handle, length):
    """
    Read an ASCII string of defined length from file.

    :param file_handle: The file handle to read from at current position

    :param length: The length of the string to read

    :returns: The string read and decoded
    """
    raw_bytes = file_handle.read(length)
    return raw_bytes.split(b"\x00")[0].decode(encoding="ascii")