From ef99cac249b97bc06aac7a056a38532b1207d1ce Mon Sep 17 00:00:00 2001
From: Johan Klokkhammer Helsing <johan.helsing@qt.io>
Date: Wed, 14 Feb 2018 16:22:25 +0100
Subject: [PATCH] Client: Fail gracefully when wl_display_connect fails

[ChangeLog][QPA plugin] If we're unable to create a connection to the Wayland
display, fail gracefully so other platform integrations can be tried instead.

This also adds QWaylandIntegration::hasFailed() which can later be extended to
report that the platform plugin is unusable for other reasons. I.e. no
compatible shell extensions or similar.

Task-number: QTBUG-59762
Change-Id: I0f1ae73982e2860814235c1a189741d130e1db3e
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
---
 src/plugins/platforms/wayland/qwaylanddisplay.cpp     | 9 +++++----
 src/plugins/platforms/wayland/qwaylandintegration.cpp | 4 ++++
 src/plugins/platforms/wayland/qwaylandintegration_p.h | 3 +++
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/plugins/platforms/wayland/qwaylanddisplay.cpp b/src/plugins/platforms/wayland/qwaylanddisplay.cpp
index 942494f93cd..179c0454e0c 100644
--- a/src/plugins/platforms/wayland/qwaylanddisplay.cpp
+++ b/src/plugins/platforms/wayland/qwaylanddisplay.cpp
@@ -142,9 +142,9 @@ QWaylandDisplay::QWaylandDisplay(QWaylandIntegration *waylandIntegration)
     qRegisterMetaType<uint32_t>("uint32_t");
 
     mDisplay = wl_display_connect(nullptr);
-    if (mDisplay == nullptr) {
-        qErrnoWarning(errno, "Failed to create display");
-        ::exit(1);
+    if (!mDisplay) {
+        qErrnoWarning(errno, "Failed to create wl_display");
+        return;
     }
 
     struct ::wl_registry *registry = wl_display_get_registry(mDisplay);
@@ -170,7 +170,8 @@ QWaylandDisplay::~QWaylandDisplay(void)
 #if QT_CONFIG(wayland_datadevice)
     delete mDndSelectionHandler.take();
 #endif
-    wl_display_disconnect(mDisplay);
+    if (mDisplay)
+        wl_display_disconnect(mDisplay);
 }
 
 void QWaylandDisplay::checkError() const
diff --git a/src/plugins/platforms/wayland/qwaylandintegration.cpp b/src/plugins/platforms/wayland/qwaylandintegration.cpp
index 698abd8fd4a..267e481ac9c 100644
--- a/src/plugins/platforms/wayland/qwaylandintegration.cpp
+++ b/src/plugins/platforms/wayland/qwaylandintegration.cpp
@@ -134,6 +134,10 @@ QWaylandIntegration::QWaylandIntegration()
 {
     initializeInputDeviceIntegration();
     mDisplay.reset(new QWaylandDisplay(this));
+    if (!mDisplay->isInitialized()) {
+        mFailed = true;
+        return;
+    }
 #if QT_CONFIG(clipboard)
     mClipboard.reset(new QWaylandClipboard(mDisplay.data()));
 #endif
diff --git a/src/plugins/platforms/wayland/qwaylandintegration_p.h b/src/plugins/platforms/wayland/qwaylandintegration_p.h
index 174eca25315..17144b8d716 100644
--- a/src/plugins/platforms/wayland/qwaylandintegration_p.h
+++ b/src/plugins/platforms/wayland/qwaylandintegration_p.h
@@ -73,6 +73,8 @@ public:
     QWaylandIntegration();
     ~QWaylandIntegration();
 
+    bool hasFailed() { return mFailed; }
+
     bool hasCapability(QPlatformIntegration::Capability cap) const override;
     QPlatformWindow *createPlatformWindow(QWindow *window) const override;
 #if QT_CONFIG(opengl)
@@ -144,6 +146,7 @@ private:
 #if QT_CONFIG(accessibility)
     QScopedPointer<QPlatformAccessibility> mAccessibility;
 #endif
+    bool mFailed = false;
     bool mClientBufferIntegrationInitialized;
     bool mServerBufferIntegrationInitialized;
     bool mShellIntegrationInitialized;