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, 8 insertions, 18 deletions

diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index e9b36c48b8..1ac5445035 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -192,25 +192,15 @@ QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char
 
     const int numParameters = parameters.size();
     m_connections.reserve(1 + numParameters / 2);
-    auto conn = new QXcbConnection(m_nativeInterface.data(), m_canGrab, m_defaultVisualId, displayName);
-    if (conn->isConnected())
-        m_connections << conn;
-    else
-        delete conn;
-
-    for (int i = 0; i < numParameters - 1; i += 2) {
-        qCDebug(lcQpaScreen) << "connecting to additional display: " << parameters.at(i) << parameters.at(i+1);
-        QString display = parameters.at(i) + QLatin1Char(':') + parameters.at(i+1);
-        conn = new QXcbConnection(m_nativeInterface.data(), m_canGrab, m_defaultVisualId, display.toLatin1().constData());
-        if (conn->isConnected())
-            m_connections << conn;
-        else
-            delete conn;
-    }
 
-    if (m_connections.isEmpty()) {
-        qCritical("Could not connect to any X display.");
-        exit(1);
+    if (QXcbConnection *defaultConnection = QXcbConnection::create(m_nativeInterface.data(), m_canGrab, m_defaultVisualId, displayName)) {
+        m_connections.append(defaultConnection);
+        for (int i = 0; i < numParameters - 1; i += 2) {
+            qCDebug(lcQpaScreen) << "connecting to additional display: " << parameters.at(i) << parameters.at(i+1);
+            QString display = parameters.at(i) + QLatin1Char(':') + parameters.at(i+1);
+            if (QXcbConnection *connection = QXcbConnection::create(m_nativeInterface.data(), m_canGrab, m_defaultVisualId, display.toLatin1().constData()))
+                m_connections.append(connection);
+        }
     }
 
     m_fontDatabase.reset(new QGenericUnixFontDatabase());