XCB: Do not create instance of QPlatformIntegration for invalid displays

Extract a static factory for QXcbConnection objects and pass
potential connection errors to qxcbmain.cpp, which will then return 0.

Task-number: QTBUG-68859
Change-Id: I9c0faf82462a78a576360c19bef251ad1d034d84
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

1 files changed, 9 insertions, 3 deletions

diff --git a/src/plugins/platforms/xcb/qxcbmain.cpp b/src/plugins/platforms/xcb/qxcbmain.cpp
index f8cb9a9269..539d033ca9 100644
--- a/src/plugins/platforms/xcb/qxcbmain.cpp
+++ b/src/plugins/platforms/xcb/qxcbmain.cpp
@@ -52,10 +52,16 @@ public:
 
 QPlatformIntegration* QXcbIntegrationPlugin::create(const QString& system, const QStringList& parameters, int &argc, char **argv)
 {
-    if (!system.compare(QLatin1String("xcb"), Qt::CaseInsensitive))
-        return new QXcbIntegration(parameters, argc, argv);
+    if (!system.compare(QLatin1String("xcb"), Qt::CaseInsensitive)) {
+        QXcbIntegration *xcbIntegration = new QXcbIntegration(parameters, argc, argv);
+        if (!xcbIntegration->hasDefaultConnection()) {
+            delete xcbIntegration;
+            return nullptr;
+        }
+        return xcbIntegration;
+    }
 
-    return 0;
+    return nullptr;
 }
 
 QT_END_NAMESPACE