encoder: Add message.EncodeToWithFDs and DecodeMessageWithFDs

Also, restore functionality to message.EncodeTo and DecodeMessage
This maintains compatibility with API v5

conn_test.go

@@ -206,7 +206,7 @@ func TestCloseBeforeSignal(t *testing.T) {
 			FieldPath:      MakeVariant(ObjectPath("/baz")),
 		},
 	}
-	_, err = msg.EncodeTo(pipewriter, binary.LittleEndian)
+	err = msg.EncodeTo(pipewriter, binary.LittleEndian)
 	if err != nil {
 		t.Fatal(err)
 	}

decoder_test.go

@@ -61,11 +61,11 @@ func TestDecodeArrayEmptyStruct(t *testing.T) {
 		},
 		serial: 0x00000003,
 	}
-	_, err := msg.EncodeTo(buf, binary.LittleEndian)
+	err := msg.EncodeTo(buf, binary.LittleEndian)
 	if err != nil {
 		t.Fatal(err)
 	}
-	msg, err = DecodeMessage(buf, make([]int, 0))
+	msg, err = DecodeMessage(buf)
 	if err != nil {
 		t.Fatal(err)
 	}

message.go

@@ -118,11 +118,7 @@ type header struct {
 	Variant
 }
 
-// DecodeMessage tries to decode a single message in the D-Bus wire format
-// from the given reader. The byte order is figured out from the first byte.
-// The possibly returned error can be an error of the underlying reader, an
-// InvalidMessageError or a FormatError.
-func DecodeMessage(rd io.Reader, fds []int) (msg *Message, err error) {
+func DecodeMessageWithFDs(rd io.Reader, fds []int) (msg *Message, err error) {
 	var order binary.ByteOrder
 	var hlength, length uint32
 	var typ, flags, proto byte
@@ -207,6 +203,14 @@ func DecodeMessage(rd io.Reader, fds []int) (msg *Message, err error) {
 	return
 }
 
+// DecodeMessage tries to decode a single message in the D-Bus wire format
+// from the given reader. The byte order is figured out from the first byte.
+// The possibly returned error can be an error of the underlying reader, an
+// InvalidMessageError or a FormatError.
+func DecodeMessage(rd io.Reader) (msg *Message, err error) {
+	return DecodeMessageWithFDs(rd, make([]int, 0));
+}
+
 type nullwriter struct{}
 
 func (nullwriter) Write(p []byte) (cnt int, err error) {
@@ -222,10 +226,7 @@ func (msg *Message) CountFds() (int, error) {
 	return len(enc.fds), err
 }
 
-// EncodeTo encodes and sends a message to the given writer. The byte order must
-// be either binary.LittleEndian or binary.BigEndian. If the message is not
-// valid or an error occurs when writing, an error is returned.
-func (msg *Message) EncodeTo(out io.Writer, order binary.ByteOrder) (fds []int, err error) {
+func (msg *Message) EncodeToWithFDs(out io.Writer, order binary.ByteOrder) (fds []int, err error) {
 	if err := msg.IsValid(); err != nil {
 		return make([]int, 0), err
 	}
@@ -274,6 +275,14 @@ func (msg *Message) EncodeTo(out io.Writer, order binary.ByteOrder) (fds []int,
 	return enc.fds, nil
 }
 
+// EncodeTo encodes and sends a message to the given writer. The byte order must
+// be either binary.LittleEndian or binary.BigEndian. If the message is not
+// valid or an error occurs when writing, an error is returned.
+func (msg *Message) EncodeTo(out io.Writer, order binary.ByteOrder) (err error) {
+	_, err = msg.EncodeToWithFDs(out, order);
+	return err;
+}
+
 // IsValid checks whether msg is a valid message and returns an
 // InvalidMessageError if it is not.
 func (msg *Message) IsValid() error {

proto_test.go

@@ -253,11 +253,11 @@ func TestMessage(t *testing.T) {
 		FieldMember: MakeVariant("baz"),
 	}
 	message.Body = make([]interface{}, 0)
-	_, err := message.EncodeTo(buf, binary.LittleEndian)
+	err := message.EncodeTo(buf, binary.LittleEndian)
 	if err != nil {
 		t.Error(err)
 	}
-	_, err = DecodeMessage(buf, make([]int, 0))
+	_, err = DecodeMessage(buf)
 	if err != nil {
 		t.Error(err)
 	}
@@ -317,15 +317,15 @@ func BenchmarkDecodeMessageSmall(b *testing.B) {
 
 	b.StopTimer()
 	buf := new(bytes.Buffer)
-	_, err = smallMessage.EncodeTo(buf, binary.LittleEndian)
+	err = smallMessage.EncodeTo(buf, binary.LittleEndian)
 	if err != nil {
 		b.Fatal(err)
 	}
 	decoded := buf.Bytes()
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		rd = bytes.NewReader(decoded)
-		_, err = DecodeMessage(rd, make([]int, 0))
+		_, err = DecodeMessage(rd)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -338,15 +338,15 @@ func BenchmarkDecodeMessageBig(b *testing.B) {
 
 	b.StopTimer()
 	buf := new(bytes.Buffer)
-	_, err = bigMessage.EncodeTo(buf, binary.LittleEndian)
+	err = bigMessage.EncodeTo(buf, binary.LittleEndian)
 	if err != nil {
 		b.Fatal(err)
 	}
 	decoded := buf.Bytes()
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		rd = bytes.NewReader(decoded)
-		_, err = DecodeMessage(rd, make([]int, 0))
+		_, err = DecodeMessage(rd)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -356,7 +356,7 @@ func BenchmarkDecodeMessageBig(b *testing.B) {
 func BenchmarkEncodeMessageSmall(b *testing.B) {
 	var err error
 	for i := 0; i < b.N; i++ {
-		_, err = smallMessage.EncodeTo(ioutil.Discard, binary.LittleEndian)
+		err = smallMessage.EncodeTo(ioutil.Discard, binary.LittleEndian)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -366,7 +366,7 @@ func BenchmarkEncodeMessageSmall(b *testing.B) {
 func BenchmarkEncodeMessageBig(b *testing.B) {
 	var err error
 	for i := 0; i < b.N; i++ {
-		_, err = bigMessage.EncodeTo(ioutil.Discard, binary.LittleEndian)
+		err = bigMessage.EncodeTo(ioutil.Discard, binary.LittleEndian)
 		if err != nil {
 			b.Fatal(err)
 		}

transport_generic.go

@@ -37,7 +37,7 @@ func (t genericTransport) SupportsUnixFDs() bool {
 func (t genericTransport) EnableUnixFDs() {}
 
 func (t genericTransport) ReadMessage() (*Message, error) {
-	return DecodeMessage(t, make([]int, 0))
+	return DecodeMessage(t)
 }
 
 func (t genericTransport) SendMessage(msg *Message) error {
@@ -48,6 +48,5 @@ func (t genericTransport) SendMessage(msg *Message) error {
 	if fds != 0 {
 		return errors.New("dbus: unix fd passing not enabled")
 	}
-	_, err = msg.EncodeTo(t, nativeEndian)
-	return err
+	return msg.EncodeTo(t, nativeEndian)
 }

transport_unix.go

@@ -147,7 +147,7 @@ func (t *unixTransport) ReadMessage() (*Message, error) {
 		if err != nil {
 			return nil, err
 		}
-		msg, err := DecodeMessage(bytes.NewBuffer(all), fds)
+		msg, err := DecodeMessageWithFDs(bytes.NewBuffer(all), fds)
 		if err != nil {
 			return nil, err
 		}
@@ -175,7 +175,7 @@ func (t *unixTransport) ReadMessage() (*Message, error) {
 		}
 		return msg, nil
 	}
-	return DecodeMessage(bytes.NewBuffer(all), make([]int, 0))
+	return DecodeMessage(bytes.NewBuffer(all))
 }
 
 func (t *unixTransport) SendMessage(msg *Message) error {
@@ -189,7 +189,7 @@ func (t *unixTransport) SendMessage(msg *Message) error {
 		}
 		msg.Headers[FieldUnixFDs] = MakeVariant(uint32(fdcnt))
 		buf := new(bytes.Buffer)
-		fds, err := msg.EncodeTo(buf, nativeEndian)
+		fds, err := msg.EncodeToWithFDs(buf, nativeEndian)
 		if err != nil {
 			return err
 		}
@@ -202,7 +202,7 @@ func (t *unixTransport) SendMessage(msg *Message) error {
 			return io.ErrShortWrite
 		}
 	} else {
-		if _, err := msg.EncodeTo(t, nativeEndian); err != nil {
+		if err := msg.EncodeTo(t, nativeEndian); err != nil {
 			return err
 		}
 	}