dbus: add support for setgid binaries

src/CMakeLists.txt

@@ -47,10 +47,10 @@ set(libinputactions_SRCS
     libinputactions/handlers/TouchscreenTriggerHandler.cpp
     libinputactions/handlers/TriggerHandler.cpp
     libinputactions/helpers/Math.cpp
+    libinputactions/helpers/QDBusConnection.cpp
     libinputactions/helpers/QString.cpp
     libinputactions/helpers/QThread.cpp
     libinputactions/helpers/QVariant.cpp
-    libinputactions/helpers/Session.cpp
     libinputactions/input/backends/InputBackend.cpp
     libinputactions/input/backends/LibevdevComplementaryInputBackend.cpp
     libinputactions/input/backends/LibinputInputBackend.cpp

src/libinputactions/dbus/IntegratedDBusInterface.cpp

@@ -21,6 +21,7 @@
 #include <libinputactions/InputActionsMain.h>
 #include <libinputactions/config/ConfigIssueManager.h>
 #include <libinputactions/config/ConfigLoader.h>
+#include <libinputactions/helpers/QDBusConnection.h>
 #include <libinputactions/input/StrokeRecorder.h>
 #include <libinputactions/input/backends/InputBackend.h>
 #include <libinputactions/interfaces/OnScreenMessageManager.h>
@@ -31,7 +32,7 @@ namespace InputActions
 {
 
 IntegratedDBusInterface::IntegratedDBusInterface()
-    : m_bus(QDBusConnection::sessionBus())
+    : m_bus(QDBusConnectionHelpers::sessionBus())
 {
     m_bus.registerService(INPUTACTIONS_DBUS_SERVICE);
     m_bus.registerObject(INPUTACTIONS_DBUS_PATH, this, QDBusConnection::ExportAllSlots);

src/libinputactions/helpers/Session.cpp → src/libinputactions/helpers/QDBusConnection.cpp

@@ -16,19 +16,32 @@
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
-#include "Session.h"
-#include <QFile>
+#include "QDBusConnection.h"
+#include <sys/types.h>
+#include <unistd.h>
 
-namespace InputActions::SessionHelpers
+namespace InputActions::QDBusConnectionHelpers
 {
 
-QString currentTty()
+const QDBusConnection &sessionBus()
 {
-    QFile f("/sys/class/tty/tty0/active");
-    if (f.open(QIODeviceBase::ReadOnly)) {
-        return QString::fromUtf8(f.readAll()).trimmed();
+    static std::optional<QDBusConnection> cached;
+    if (cached) {
+        return cached.value();
     }
-    return "unknown";
+
+    gid_t rgid{};
+    gid_t egid{};
+    gid_t sgid{};
+    if (!getresgid(&rgid, &egid, &sgid) && (rgid != egid || egid != sgid)) {
+        if (const auto address = qEnvironmentVariable("DBUS_SESSION_BUS_ADDRESS"); !address.isEmpty()) {
+            cached = QDBusConnection::connectToBus(address, "sessionBus");
+            return cached.value();
+        }
+    }
+
+    cached = QDBusConnection::sessionBus();
+    return cached.value();
 }
 
 }

src/libinputactions/helpers/Session.h → src/libinputactions/helpers/QDBusConnection.h

@@ -18,11 +18,17 @@
 
 #pragma once
 
-#include <QString>
+#include <QDBusConnection>
 
-namespace InputActions::SessionHelpers
+namespace InputActions::QDBusConnectionHelpers
 {
 
-QString currentTty();
+/**
+ * Same as QDBusConnection::sessionBus, but uses QDBusConnection::connectToBus with the address specified in the DBUS_SESSION_BUS_ADDRESS environment variable
+ * for setgid binaries.
+ * 
+ * Connection is cached.
+ */
+const QDBusConnection &sessionBus();
 
 }

src/libinputactions/interfaces/implementations/DBusNotificationManager.cpp

@@ -19,6 +19,7 @@
 #include "DBusNotificationManager.h"
 #include <QDBusInterface>
 #include <QThreadPool>
+#include <libinputactions/helpers/QDBusConnection.h>
 
 namespace InputActions
 {
@@ -31,7 +32,7 @@ void DBusNotificationManager::sendNotification(const QString &title, const QStri
         QDBusInterface notificationsInterface("org.freedesktop.Notifications",
                                               "/org/freedesktop/Notifications",
                                               "org.freedesktop.Notifications",
-                                              QDBusConnection::sessionBus());
+                                              QDBusConnectionHelpers::sessionBus());
         if (notificationsInterface.isValid()) {
             notificationsInterface.asyncCall("Notify", "InputActions", 0U, "", title, content, QStringList(), QVariantMap(), 5000);
         }