From 875e44f56d4597ba3b65f5bf4ff2b315376c05a4 Mon Sep 17 00:00:00 2001
From: Kai Uwe Broulik <kde@privat.broulik.de>
Date: Wed, 11 Jul 2018 18:01:41 +0200
Subject: Force software rendering when greeter crashed

We have a fallback QML theme for when the look and feel package is broken but when the
graphics driver is broken (e.g. proprietary graphics driver update) the lock screen would
stop working. When the greeter crashed, better play safe and force software rendering

Reviewed-By: d_ed
---
 ksldapp.cpp | 13 +++++++++++--
 ksldapp.h   |  9 +++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/ksldapp.cpp b/ksldapp.cpp
index 892826f..5fe28ea 100644
--- a/ksldapp.cpp
+++ b/ksldapp.cpp
@@ -66,6 +66,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 namespace ScreenLocker
 {
 
+static const QString s_qtQuickBackend = QStringLiteral("QT_QUICK_BACKEND");
+
 static KSldApp * s_instance = nullptr;
 
 KSldApp* KSldApp::self()
@@ -226,6 +228,8 @@ void KSldApp::initialize()
             // failure, restart lock process
             m_greeterCrashedCounter++;
             if (m_greeterCrashedCounter < 4) {
+                // Perhaps it crashed due to a graphics driver issue, force software rendering now
+                setForceSoftwareRendering(true);
                 startLockProcess(EstablishLock::Immediate);
             } else if (m_lockWindow) {
                 m_lockWindow->emergencyShow();
@@ -385,6 +389,7 @@ void KSldApp::lock(EstablishLock establishLock)
 
     m_lockState = AcquiringLock;
 
+    setForceSoftwareRendering(false);
     // start unlock screen process
     startLockProcess(establishLock);
     emit lockStateChanged();
@@ -546,6 +551,8 @@ bool KSldApp::isFdoPowerInhibited() const
 
 void KSldApp::startLockProcess(EstablishLock establishLock)
 {
+    QProcessEnvironment env = m_greeterEnv;
+
     if (m_isWayland && m_waylandDisplay) {
         int sx[2];
         if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, sx) < 0) {
@@ -566,9 +573,7 @@ void KSldApp::startLockProcess(EstablishLock establishLock)
         emit greeterClientConnectionChanged();
         int socket = dup(sx[1]);
         if (socket >= 0) {
-            QProcessEnvironment env = m_greeterEnv;
             env.insert("WAYLAND_SOCKET", QByteArray::number(socket));
-            m_lockProcess->setProcessEnvironment(env);
         }
     }
     QStringList args;
@@ -587,6 +592,9 @@ void KSldApp::startLockProcess(EstablishLock establishLock)
     if (m_lockGrace == -1) {
         args << QStringLiteral("--nolock");
     }
+    if (m_forceSoftwareRendering) {
+        env.insert(s_qtQuickBackend, QStringLiteral("software"));
+    }
 
     // start the Wayland server
     int fd = m_waylandServer->start();
@@ -598,6 +606,7 @@ void KSldApp::startLockProcess(EstablishLock establishLock)
     args << QStringLiteral("--ksldfd");
     args << QString::number(fd);
 
+    m_lockProcess->setProcessEnvironment(env);
     m_lockProcess->start(QStringLiteral(KSCREENLOCKER_GREET_BIN), args);
     close(fd);
 }
diff --git a/ksldapp.h b/ksldapp.h
index 4849588..b6d6703 100644
--- a/ksldapp.h
+++ b/ksldapp.h
@@ -127,6 +127,14 @@ public:
         m_lockGrace = msec;
     }
 
+    bool forceSoftwareRendering() const {
+        return m_forceSoftwareRendering;
+    }
+
+    void setForceSoftwareRendering(bool force) {
+        m_forceSoftwareRendering = force;
+    }
+
 Q_SIGNALS:
     void locked();
     void unlocked();
@@ -179,6 +187,7 @@ private:
     LogindIntegration *m_logind;
     GlobalAccel *m_globalAccel = nullptr;
     bool m_hasXInput2 = false;
+    bool m_forceSoftwareRendering = false;
 
     bool m_isX11;
     bool m_isWayland;
-- 
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