feat: watch systemd unit new and remove to sync state

add default values to XDG_DATA_DIRS if it dosen't set

Signed-off-by: ComixHe <heyuming@deepin.org>
Signed-off-by: black-desk <me@black-desk.cn>

src/systemdsignaldispatcher.cpp

@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: 2023 UnionTech Software Technology Co., Ltd.
+//
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+#include "systemdsignaldispatcher.h"
+
+bool SystemdSignalDispatcher::connectToSignals() noexcept
+{
+    auto &con = ApplicationManager1DBus::instance().globalDestBus();
+
+    if (!con.connect(SystemdService,
+                     SystemdObjectPath,
+                     SystemdInterfaceName,
+                     "UnitNew",
+                     this,
+                     SLOT(onUnitNew(QString, QDBusObjectPath)))) {
+        qCritical() << "can't connect to UnitNew signal of systemd service.";
+        return false;
+    }
+
+    if (!con.connect(SystemdService,
+                     SystemdObjectPath,
+                     SystemdInterfaceName,
+                     "UnitRemoved",
+                     this,
+                     SLOT(onUnitRemoved(QString, QDBusObjectPath)))) {
+        qCritical() << "can't connect to UnitRemoved signal of systemd service.";
+        return false;
+    }
+
+    return true;
+}
+
+void SystemdSignalDispatcher::onUnitNew(QString serviceName, QDBusObjectPath systemdUnitPath)
+{
+    if (!serviceName.startsWith("app-")) {
+        return;
+    }
+
+    emit SystemdUnitNew(serviceName.sliced(4), systemdUnitPath);  // remove "app-"
+}
+
+void SystemdSignalDispatcher::onUnitRemoved(QString serviceName, QDBusObjectPath systemdUnitPath)
+{
+    if (!serviceName.startsWith("app-")) {
+        return;
+    }
+
+    emit SystemdUnitRemoved(serviceName.sliced(4), systemdUnitPath);
+}