fix(serial) keep serial console mux closed when not needed

Only open the serial console mux and broker when the extension is
actually in use, otherwise the mux gets in a fight with the ATX or DC
control extension in reading from the serial port.

Closes: #1420

Author: dseven

jsonrpc.go

@@ -770,6 +770,8 @@ func rpcSetActiveExtension(extensionId string) error {
 		_ = unmountATXControl()
 	case "dc-power":
 		_ = unmountDCControl()
+	case "serial-console":
+		_ = unmountSerialConsole()
 	}
 	config.ActiveExtension = extensionId
 	if err := SaveConfig(); err != nil {
@@ -780,6 +782,8 @@ func rpcSetActiveExtension(extensionId string) error {
 		_ = mountATXControl()
 	case "dc-power":
 		_ = mountDCControl()
+	case "serial-console":
+		_ = mountSerialConsole()
 	}
 
 	// Re-publish MQTT HA Discovery for the new extension

serial.go

@@ -580,10 +580,20 @@ func initSerialPort() {
 		_ = mountATXControl()
 	case "dc-power":
 		_ = mountDCControl()
+	case "serial-console":
+		_ = mountSerialConsole()
 	}
 }
 
 func reopenSerialPort() error {
+	if serialMux != nil {
+		serialMux.Close()
+		serialMux = nil
+	}
+	if consoleBroker != nil {
+		consoleBroker.Close()
+		consoleBroker = nil
+	}
 	if port != nil {
 		port.Close()
 	}
@@ -598,6 +608,10 @@ func reopenSerialPort() error {
 		return err
 	}
 
+	return nil
+}
+
+func mountSerialConsole() error {
 	// new broker (no sink yet—set it in handleSerialChannel.OnOpen)
 	norm := NormalizationOptions{
 		Mode: ModeNames, LineEnding: LineEnding_LF, TabRender: "", PreserveANSI: true,
@@ -619,6 +633,11 @@ func reopenSerialPort() error {
 	return nil
 }
 
+func unmountSerialConsole() error {
+	_ = reopenSerialPort()
+	return nil
+}
+
 func handleSerialChannel(dataChannel *webrtc.DataChannel) {
 	scopedLogger := serialLogger.With().
 		Uint16("data_channel_id", *dataChannel.ID()).Str("service", "serial terminal channel").Logger()

serial_console_helpers.go

@@ -273,9 +273,16 @@ func NewConsoleBroker(s Sink, norm NormalizationOptions) *ConsoleBroker {
 }
 
 func (b *ConsoleBroker) Start()                                   { go b.loop() }
-func (b *ConsoleBroker) Close()                                   { close(b.done) }
 func (b *ConsoleBroker) SetSink(s Sink)                           { b.sink = s }
 func (b *ConsoleBroker) SetNormOptions(norm NormalizationOptions) { b.norm = norm }
+func (b *ConsoleBroker) Close() {
+	select {
+	case <-b.done:
+		return
+	default:
+		close(b.done)
+	}
+}
 func (b *ConsoleBroker) SetTerminalPaused(v bool) {
 	if b == nil {
 		return
@@ -626,7 +633,14 @@ func (m *SerialMux) Start() {
 	go m.writer()
 }
 
-func (m *SerialMux) Close() { close(m.done) }
+func (m *SerialMux) Close() {
+	select {
+	case <-m.done:
+		return
+	default:
+		close(m.done)
+	}
+}
 
 func (m *SerialMux) SetEchoEnabled(v bool) { m.echoEnabled.Store(v) }