Add --force-update: immediate signed-update check, stage + service restart

internal/service/service_windows.go

@@ -351,3 +351,48 @@ func configuredLogFile(configPath string) string {
 	}
 	return values["LOG_FILE"]
 }
+
+// RestartIfRunning restarts the service when it is installed and running
+// (used after a forced update staged a new binary). Reports whether a
+// restart happened. A service that is not installed or not running is not
+// an error. Needs elevation.
+func RestartIfRunning() (bool, error) {
+	m, err := mgr.Connect()
+	if err != nil {
+		return false, fmt.Errorf("connect to service manager (run as administrator): %w", err)
+	}
+	defer m.Disconnect()
+	s, err := m.OpenService(Name)
+	if err != nil {
+		return false, nil // not installed
+	}
+	defer s.Close()
+	st, err := s.Query()
+	if err != nil {
+		return false, fmt.Errorf("query service: %w", err)
+	}
+	if st.State != svc.Running && st.State != svc.StartPending {
+		return false, nil
+	}
+	if _, err := s.Control(svc.Stop); err != nil {
+		return false, fmt.Errorf("stop service: %w", err)
+	}
+	deadline := time.Now().Add(30 * time.Second)
+	for {
+		st, err = s.Query()
+		if err != nil {
+			return false, fmt.Errorf("query service: %w", err)
+		}
+		if st.State == svc.Stopped {
+			break
+		}
+		if time.Now().After(deadline) {
+			return false, fmt.Errorf("service did not stop within 30s")
+		}
+		time.Sleep(300 * time.Millisecond)
+	}
+	if err := s.Start(); err != nil {
+		return false, fmt.Errorf("start service: %w", err)
+	}
+	return true, nil
+}