added update check result as global MQTT topic

src/ebusd/datahandler.h

@@ -145,15 +145,20 @@ class DataSink : virtual public DataHandler {
    */
   virtual ~DataSink() {}
 
+  // @copydoc
+  bool isDataSink() override { return true; }
+
   /**
    * Notify the sink of an updated @a Message.
    * @param message the updated @a Message.
    */
   virtual void notifyUpdate(Message* message);
 
-  // @copydoc
+  /**
-  bool isDataSink() override { return true; }
+   * Notify the sink of the latest update check result.
-
+   * @param checkResult a string describing available updates, or empty if no update is available.
+   */
+  virtual void notifyUpdateCheckResult(string checkResult) {}
 
  protected:
   /** the allowed access levels. */

src/ebusd/mainloop.cpp

@@ -357,6 +357,11 @@ void MainLoop::run() {
               if (result == "200 OK") {
                 m_updateCheck = message == "" ? "unknown" : message;
                 logNotice(lf_main, "update check: %s", message.c_str());
+                if (!dataSinks.empty()) {
+                  for (list<DataSink*>::iterator it = dataSinks.begin(); it != dataSinks.end(); it++) {
+                    (*it)->notifyUpdateCheckResult(message == "OK" ? "" : m_updateCheck);
+                  }
+                }
               } else {
                 logError(lf_main, "update check error: %s", result.c_str());
               }

src/ebusd/mqtthandler.cpp

@@ -261,7 +261,8 @@ void on_connect(
 
 
 MqttHandler::MqttHandler(UserInfo* userInfo, BusHandler* busHandler, MessageMap* messages)
-  : DataSink(userInfo, "mqtt"), DataSource(busHandler), Thread(), m_messages(messages), m_connected(false) {
+  : DataSink(userInfo, "mqtt"), DataSource(busHandler), Thread(), m_messages(messages), m_connected(false),
+    m_lastUpdateCheckResult(".") {
   bool enabled = g_port != 0;
   m_publishByField = false;
   m_mosquitto = NULL;
@@ -478,6 +479,13 @@ void MqttHandler::notifyTopic(string topic, string data) {
   publishMessage(message, ostream);
 }
 
+void MqttHandler::notifyUpdateCheckResult(string checkResult) {
+  if (checkResult != m_lastUpdateCheckResult) {
+    m_lastUpdateCheckResult = checkResult;
+    publishTopic(m_globalTopic+"updatecheck", checkResult.empty() ? "OK" : checkResult);
+  }
+}
+
 void MqttHandler::run() {
   time_t lastTaskRun, now, start, lastSignal = 0;
   bool signal = false;

src/ebusd/mqtthandler.h

@@ -80,6 +80,8 @@ class MqttHandler : public DataSink, public DataSource, public Thread {
    */
   void notifyTopic(string topic, string data);
 
+  // @copydoc
+  void notifyUpdateCheckResult(string checkResult) override;
 
  protected:
   // @copydoc
@@ -135,6 +137,9 @@ class MqttHandler : public DataSink, public DataSource, public Thread {
 
   /** whether the connection to the broker is established. */
   bool m_connected;
+
+  /** the last update check result. */
+  string m_lastUpdateCheckResult;
 };
 
 }  // namespace ebusd