case bytes.HasPrefix(ident, []byte{0x01, 0xDF}) || bytes.HasPrefix(ident, []byte{0x01, 0xF7}):
		f, err := xcoff.NewFile(r)
		if err != nil {
			return "", "", errUnrecognizedFormat
		}
		x = &xcoffExe{f}
	case hasPlan9Magic(ident):
		f, err := plan9obj.NewFile(r)
		if err != nil {
			return "", "", errUnrecognizedFormat
		}
		x = &plan9objExe{f}
	default:
		return "", "", errUnrecognizedFormat
	}