Prevent tdenetworkmanager from crashing when using unmanaged devices.

This relates to bug 2929.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

tdecore/tdehw/networkbackends/network-manager/network-manager.cpp

@@ -1156,16 +1156,16 @@ TQString TDENetworkConnectionManager_BackendNM::deviceInterfaceString(TQString d
 					return (*it);
 				}
 			}
-			return "";
+			return TQString::null;
 		}
 		else {
 			// Error!
 			PRINT_ERROR((error.name() + ": " + error.message()))
-			return "";
+			return TQString::null;
 		}
 	}
 	else {
-		return "";
+		return TQString::null;
 	}
 }
 
@@ -1249,7 +1249,7 @@ TDENetworkConnectionManager_BackendNM::TDENetworkConnectionManager_BackendNM(TDE
 	d->m_vpnProxy->setConnection(TQT_DBusConnection::systemBus());
 
 	d->m_dbusDeviceString = deviceInterfaceString(deviceNode());
-	if (d->m_dbusDeviceString != "") {
+	if (!d->m_dbusDeviceString.isEmpty()) {
 		d->m_networkDeviceProxy = new DBus::DeviceProxy(NM_DBUS_SERVICE, d->m_dbusDeviceString);
 		d->m_networkDeviceProxy->setConnection(TQT_DBusConnection::systemBus());
 		if (deviceType() == TDENetworkDeviceType::WiFi) {
@@ -1567,11 +1567,11 @@ TDENetworkDeviceType::TDENetworkDeviceType TDENetworkConnectionManager_BackendNM
 	if (!m_networkDevice) {
 		return TDENetworkDeviceType::BackendOnly;
 	}
-	else {
-		if (d->m_dbusDeviceString != "") {
+
 	// Query NM for the device type
 	TQT_DBusError error;
 	d->m_dbusDeviceString = deviceInterfaceString(deviceNode());
+	if (!d->m_dbusDeviceString.isEmpty()) {
 		DBus::DeviceProxy genericDevice(NM_DBUS_SERVICE, d->m_dbusDeviceString);
 		genericDevice.setConnection(TQT_DBusConnection::systemBus());
 		TDENetworkDeviceType::TDENetworkDeviceType ret = nmDeviceTypeToTDEDeviceType(genericDevice.getDeviceType(error));
@@ -1586,11 +1586,10 @@ TDENetworkDeviceType::TDENetworkDeviceType TDENetworkConnectionManager_BackendNM
 	}
 	else {
 		// Error!
-			PRINT_ERROR(TQString("Invalid DBUS device string '%1'").arg(d->m_dbusDeviceString))
+		PRINT_ERROR(TQString("Invalid empty DBUS device string"))
 		return TDENetworkDeviceType::Other;
 	}
 }
-}
 
 TDENetworkConnectionType::TDENetworkConnectionType TDENetworkConnectionManager_BackendNM::connectionType(TQString dbusPath) {
 	TDENetworkConnectionType::TDENetworkConnectionType connType = TDENetworkConnectionType::Other;
@@ -4791,6 +4790,10 @@ TDENetworkConnectionStatus::TDENetworkConnectionStatus TDENetworkConnectionManag
 			else {
 				d->m_dbusDeviceString = deviceInterfaceString(deviceNode());
 			}
+			if (d->m_dbusDeviceString.isEmpty()) {
+				PRINT_ERROR(TQString("Invalid empty DBUS device string"))
+				return TDENetworkConnectionStatus::Invalid;
+			}
 #ifndef USE_ASYNC_DBUS_CONNECTION_COMMAND_CALLS
 			TQT_DBusObjectPath active_connection;
 			ret = d->m_networkManagerProxy->ActivateConnection(existingConnection, TQT_DBusObjectPath(d->m_dbusDeviceString.ascii()), TQT_DBusObjectPath("/"), active_connection, error);
@@ -4984,6 +4987,10 @@ TDENetworkConnectionStatus::TDENetworkConnectionStatus TDENetworkConnectionManag
 			else {
 				d->m_dbusDeviceString = deviceInterfaceString(deviceNode());
 			}
+			if (d->m_dbusDeviceString.isEmpty()) {
+				PRINT_ERROR(TQString("Invalid empty DBUS device string"))
+				return TDENetworkConnectionStatus::Invalid;
+			}
 #ifndef USE_ASYNC_DBUS_CONNECTION_COMMAND_CALLS
 			ret = d->m_networkManagerProxy->DeactivateConnection(existingConnection, error);
 			if (ret && error.isValid()) {
@@ -5270,6 +5277,7 @@ TDENetworkHWNeighborList* TDENetworkConnectionManager_BackendNM::siteSurvey() {
 	clearTDENetworkHWNeighborList();
 
 	if (myDeviceType == TDENetworkDeviceType::WiFi) {
+		if (!d->m_dbusDeviceString.isEmpty()) {
 			DBus::WiFiDeviceProxy wiFiDevice(NM_DBUS_SERVICE, d->m_dbusDeviceString);
 			wiFiDevice.setConnection(TQT_DBusConnection::systemBus());
 			// FIXME
@@ -5288,6 +5296,7 @@ TDENetworkHWNeighborList* TDENetworkConnectionManager_BackendNM::siteSurvey() {
 				}
 			}
 		}
+	}
 
 	return m_hwNeighborList;
 }