Close screen grabbing effect when screensaver starts

Summary:
The screenlock fails on X11 if it can't grab the keyboard.

We can't nicely solve the generic case. We can solve the common case of
a kwin effect being active.

It's not critical, arguably not even desirable to have these effects
persist after the screen is locked through an external trigger. We can
just close the effect early.

Key grabs have to be relased early before the close animation completes
so that the locker doesn't have a race based on animation times.

It's not ideal, but no worse than the current state for not much work.

BUG: 234153

Test Plan:
locked screen on a timer
opened various effects

Reviewers: #kwin, zzag

Reviewed By: #kwin, zzag

Subscribers: ngraham, zzag, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D20890

CMakeLists.txt

@@ -556,6 +556,7 @@ qt5_add_dbus_adaptor( kwin_KDEINIT_SRCS org.kde.kwin.OrientationSensor.xml orien
 qt5_add_dbus_adaptor( kwin_KDEINIT_SRCS org.kde.KWin.VirtualDesktopManager.xml dbusinterface.h KWin::VirtualDesktopManagerDBusInterface )
 
 qt5_add_dbus_interface( kwin_KDEINIT_SRCS ${KSCREENLOCKER_DBUS_INTERFACES_DIR}/kf5_org.freedesktop.ScreenSaver.xml screenlocker_interface )
+qt5_add_dbus_interface( kwin_KDEINIT_SRCS ${KSCREENLOCKER_DBUS_INTERFACES_DIR}/org.kde.screensaver.xml kscreenlocker_interface )
 
 qt5_add_dbus_interface( kwin_KDEINIT_SRCS org.kde.kappmenu.xml appmenu_interface )
 

effects.cpp

@@ -212,6 +212,7 @@ EffectsHandlerImpl::EffectsHandlerImpl(Compositor *compositor, Scene *scene)
 #endif
     connect(ScreenEdges::self(), &ScreenEdges::approaching, this, &EffectsHandler::screenEdgeApproaching);
     connect(ScreenLockerWatcher::self(), &ScreenLockerWatcher::locked, this, &EffectsHandler::screenLockingChanged);
+    connect(ScreenLockerWatcher::self(), &ScreenLockerWatcher::aboutToLock, this, &EffectsHandler::screenAboutToLock);
 
     connect(kwinApp(), &Application::x11ConnectionChanged, this,
         [this] {

effects/cube/cube.cpp

@@ -101,6 +101,16 @@ CubeEffect::CubeEffect()
     connect(effects, &EffectsHandler::tabBoxAdded, this, &CubeEffect::slotTabBoxAdded);
     connect(effects, &EffectsHandler::tabBoxClosed, this, &CubeEffect::slotTabBoxClosed);
     connect(effects, &EffectsHandler::tabBoxUpdated, this, &CubeEffect::slotTabBoxUpdated);
+    connect(effects, &EffectsHandler::screenAboutToLock, this, [this]() {
+        // Set active(false) does not release key grabs until the animation completes
+        // As we know the lockscreen is trying to grab them, release them early
+        // all other grabs are released in the normal way
+        setActive(false);
+        if (keyboard_grab) {
+            effects->ungrabKeyboard();
+            keyboard_grab = false;
+        }
+    });
 
     reconfigure(ReconfigureAll);
 }

effects/desktopgrid/desktopgrid.cpp

@@ -88,6 +88,14 @@ DesktopGridEffect::DesktopGridEffect()
     connect(effects, &EffectsHandler::windowGeometryShapeChanged, this, &DesktopGridEffect::slotWindowGeometryShapeChanged);
     connect(effects, &EffectsHandler::numberScreensChanged, this, &DesktopGridEffect::setup);
 
+    connect(effects, &EffectsHandler::screenAboutToLock, this, [this]() {
+        setActive(false);
+        if (keyboardGrab) {
+            effects->ungrabKeyboard();
+            keyboardGrab = false;
+        }
+    });
+
     // Load all other configuration details
     reconfigure(ReconfigureAll);
 }

effects/flipswitch/flipswitch.cpp

@@ -75,6 +75,10 @@ FlipSwitchEffect::FlipSwitchEffect()
     connect(effects, &EffectsHandler::tabBoxClosed, this, &FlipSwitchEffect::slotTabBoxClosed);
     connect(effects, &EffectsHandler::tabBoxUpdated, this, &FlipSwitchEffect::slotTabBoxUpdated);
     connect(effects, &EffectsHandler::tabBoxKeyEvent, this, &FlipSwitchEffect::slotTabBoxKeyEvent);
+    connect(effects, &EffectsHandler::screenAboutToLock, this, [this]() {
+        setActive(false, AllDesktopsMode);
+        setActive(false, CurrentDesktopMode);
+    });
 }
 
 FlipSwitchEffect::~FlipSwitchEffect()

effects/presentwindows/presentwindows.cpp

@@ -111,6 +111,9 @@ PresentWindowsEffect::PresentWindowsEffect()
                 reCreateGrids();
         }
     );
+    connect(effects, &EffectsHandler::screenAboutToLock, this, [this]() {
+        setActive(false);
+    });
 }
 
 PresentWindowsEffect::~PresentWindowsEffect()

libkwineffects/kwineffects.h

@@ -1661,6 +1661,13 @@ Q_SIGNALS:
      **/
     void screenLockingChanged(bool locked);
 
+    /**
+     * This signal is emitted just before the screen locker tries to grab keys and lock the screen
+     * Effects should release any grabs immediately
+     * @since 5.17
+     **/
+    void screenAboutToLock();
+
     /**
      * This signels is emitted when ever the stacking order is change, ie. a window is risen
      * or lowered

screenlockerwatcher.cpp

@@ -24,6 +24,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QtConcurrentRun>
 // dbus generated
 #include "screenlocker_interface.h"
+#include "kscreenlocker_interface.h"
 
 namespace KWin
 {
@@ -34,7 +35,6 @@ static const QString SCREEN_LOCKER_SERVICE_NAME = QStringLiteral("org.freedeskto
 
 ScreenLockerWatcher::ScreenLockerWatcher(QObject *parent)
     : QObject(parent)
-    , m_interface(NULL)
     , m_serviceWatcher(new QDBusServiceWatcher(this))
     , m_locked(false)
 {
@@ -70,13 +70,18 @@ void ScreenLockerWatcher::serviceOwnerChanged(const QString &serviceName, const
         return;
     }
     delete m_interface;
-    m_interface = NULL;
+    m_interface = nullptr;
+    delete m_kdeInterface;
+    m_kdeInterface = nullptr;
+
     m_locked = false;
     if (!newOwner.isEmpty()) {
         m_interface = new OrgFreedesktopScreenSaverInterface(newOwner, QStringLiteral("/ScreenSaver"), QDBusConnection::sessionBus(), this);
+        m_kdeInterface = new OrgKdeScreensaverInterface(newOwner, QStringLiteral("/ScreenSaver"), QDBusConnection::sessionBus(), this);
         connect(m_interface, SIGNAL(ActiveChanged(bool)), SLOT(setLocked(bool)));
         QDBusPendingCallWatcher *watcher = new QDBusPendingCallWatcher(m_interface->GetActive(), this);
         connect(watcher, SIGNAL(finished(QDBusPendingCallWatcher*)), SLOT(activeQueried(QDBusPendingCallWatcher*)));
+        connect(m_kdeInterface, &OrgKdeScreensaverInterface::AboutToLock, this, &ScreenLockerWatcher::aboutToLock);
     }
 }
 

screenlockerwatcher.h

@@ -25,6 +25,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <kwinglobals.h>
 
 class OrgFreedesktopScreenSaverInterface;
+class OrgKdeScreensaverInterface;
 class QDBusServiceWatcher;
 class QDBusPendingCallWatcher;
 
@@ -41,6 +42,7 @@ public:
     }
 Q_SIGNALS:
     void locked(bool locked);
+    void aboutToLock();
 private Q_SLOTS:
     void setLocked(bool activated);
     void activeQueried(QDBusPendingCallWatcher *watcher);
@@ -49,7 +51,8 @@ private Q_SLOTS:
     void serviceOwnerQueried();
 private:
     void initialize();
-    OrgFreedesktopScreenSaverInterface *m_interface;
+    OrgFreedesktopScreenSaverInterface *m_interface = nullptr;
+    OrgKdeScreensaverInterface *m_kdeInterface = nullptr;
     QDBusServiceWatcher *m_serviceWatcher;
     bool m_locked;