// Close has no effect.
func (f *File) Close() error {
	var err error
	if f.closer != nil {
		err = f.closer.Close()
		f.closer = nil
	}
	return err
}

func parseMagic(magic []byte) (uint32, error) {
	m := binary.BigEndian.Uint32(magic)
	switch m {
	case Magic386, MagicAMD64, MagicARM:
		return m, nil
	}
	return 0, &formatError{0, "bad magic number", magic}
}