QDBusMenuConnection: Close open D-Bus connection

Using QSystemTrayIcon::isSystemTrayAvailable() generates a new
connection from QDBusTrayIcon::isSystemTrayAvailable() with a new unique instance ID.
These were never closed, so calling
QSystemTrayIcon::isSystemTrayAvailable() frequently leads to crash when
it runs out of file descriptors.

Fixes: QTBUG-94839
Pick-to: 5.15 6.1 6.2
Change-Id: Ib71441a6b680d8633707cc02f9b6081c0f02472b
Reviewed-by: Dmitry Shachnev <mitya57@gmail.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

2 files changed, 9 insertions, 0 deletions

diff --git a/src/gui/platform/unix/dbusmenu/qdbusmenuconnection.cpp b/src/gui/platform/unix/dbusmenu/qdbusmenuconnection.cpp
index d6eb8c255c..ce95ee96b4 100644
--- a/src/gui/platform/unix/dbusmenu/qdbusmenuconnection.cpp
+++ b/src/gui/platform/unix/dbusmenu/qdbusmenuconnection.cpp
@@ -70,6 +70,7 @@ const QString MenuBarPath = QLatin1String("/MenuBar");
 */
 QDBusMenuConnection::QDBusMenuConnection(QObject *parent, const QString &serviceName)
     : QObject(parent)
+    , m_serviceName(serviceName)
     , m_connection(serviceName.isNull() ? QDBusConnection::sessionBus()
                                         : QDBusConnection::connectToBus(QDBusConnection::SessionBus, serviceName))
     , m_dbusWatcher(new QDBusServiceWatcher(StatusNotifierWatcherService, m_connection, QDBusServiceWatcher::WatchForRegistration, this))
@@ -84,6 +85,12 @@ QDBusMenuConnection::QDBusMenuConnection(QObject *parent, const QString &service
 #endif
 }
 
+QDBusMenuConnection::~QDBusMenuConnection()
+{
+  if (!m_serviceName.isEmpty() && m_connection.isConnected())
+      QDBusConnection::disconnectFromBus(m_serviceName);
+}
+
 void QDBusMenuConnection::dbusError(const QDBusError &error)
 {
     qWarning() << "QDBusTrayIcon encountered a D-Bus error:" << error;
diff --git a/src/gui/platform/unix/dbusmenu/qdbusmenuconnection_p.h b/src/gui/platform/unix/dbusmenu/qdbusmenuconnection_p.h
index 37183b021d..012f83fe0e 100644
--- a/src/gui/platform/unix/dbusmenu/qdbusmenuconnection_p.h
+++ b/src/gui/platform/unix/dbusmenu/qdbusmenuconnection_p.h
@@ -71,6 +71,7 @@ class QDBusMenuConnection : public QObject
 
 public:
     QDBusMenuConnection(QObject *parent = nullptr, const QString &serviceName = QString());
+    ~QDBusMenuConnection();
     QDBusConnection connection() const { return m_connection; }
     QDBusServiceWatcher *dbusWatcher() const { return m_dbusWatcher; }
     bool isStatusNotifierHostRegistered() const { return m_statusNotifierHostRegistered; }
@@ -91,6 +92,7 @@ private Q_SLOTS:
     void dbusError(const QDBusError &error);
 
 private:
+    QString m_serviceName;
     QDBusConnection m_connection;
     QDBusServiceWatcher *m_dbusWatcher;
     bool m_statusNotifierHostRegistered;