From 67cc8fea106c35c7ca75bf476667d07b3bbf3257 Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@qt.io>
Date: Mon, 19 Feb 2018 11:07:43 +0100
Subject: 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>
---
 src/plugins/platforms/xcb/qxcbconnection.cpp | 58 +++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 15 deletions(-)

(limited to 'src/plugins/platforms/xcb/qxcbconnection.cpp')

diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index c14f3f3703..6fe1a121d8 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -544,31 +544,59 @@ void QXcbConnection::initializeScreens()
     }
 }
 
-QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGrabServer, xcb_visualid_t defaultVisualId, const char *displayName)
-    : m_canGrabServer(canGrabServer)
-    , m_defaultVisualId(defaultVisualId)
-    , m_displayName(displayName ? QByteArray(displayName) : qgetenv("DISPLAY"))
-    , m_nativeInterface(nativeInterface)
-{
+QXcbConnection *QXcbConnection::create(QXcbNativeInterface *nativeInterface, bool canGrabServer,
+                                       xcb_visualid_t defaultVisualId,
+                                       const char *displayNameIn)
+{
+    const QByteArray displayName = displayNameIn ? QByteArray(displayNameIn) : qgetenv("DISPLAY");
+    int primaryScreenNumber = 0;
+    void *xlibDisplay = nullptr;
+    xcb_connection_t *connection = nullptr;
 #if QT_CONFIG(xcb_xlib)
-    Display *dpy = XOpenDisplay(m_displayName.constData());
+    Display *dpy = XOpenDisplay(displayName.constData());
     if (dpy) {
-        m_primaryScreenNumber = DefaultScreen(dpy);
-        m_connection = XGetXCBConnection(dpy);
+        primaryScreenNumber = DefaultScreen(dpy);
+        connection = XGetXCBConnection(dpy);
         XSetEventQueueOwner(dpy, XCBOwnsEventQueue);
         XSetErrorHandler(nullErrorHandler);
         XSetIOErrorHandler(ioErrorHandler);
-        m_xlib_display = dpy;
+        xlibDisplay = dpy;
     }
 #else
-    m_connection = xcb_connect(m_displayName.constData(), &m_primaryScreenNumber);
+    connection = xcb_connect(displayName.constData(), &primaryScreenNumber);
 #endif // QT_CONFIG(xcb_xlib)
-
-    if (Q_UNLIKELY(!m_connection || xcb_connection_has_error(m_connection))) {
-        qCWarning(lcQpaScreen, "QXcbConnection: Could not connect to display %s", m_displayName.constData());
-        return;
+    if (Q_UNLIKELY(connection == nullptr)) {
+        qWarning("QXcbConnection: Could not connect to display \"%s\"", displayName.constData());
+        return nullptr;
+    }
+    if (Q_UNLIKELY(xcb_connection_has_error(connection))) {
+#if QT_CONFIG(xcb_xlib)
+        XCloseDisplay(static_cast<Display *>(xlibDisplay));
+#else
+        xcb_disconnect(connection);
+#endif
+        qWarning("QXcbConnection: Errors occurred connecting to display \"%s\"", displayName.constData());
+        return nullptr;
     }
+    return new QXcbConnection(connection, primaryScreenNumber, nativeInterface,
+                              canGrabServer, defaultVisualId, displayName, xlibDisplay);
+}
 
+
+QXcbConnection::QXcbConnection(xcb_connection_t *c, int primaryScreenNumber,
+                               QXcbNativeInterface *nativeInterface, bool canGrabServer,
+                               xcb_visualid_t defaultVisualId, const QByteArray &displayName,
+                               void *xlibDisplay)
+    : m_connection(c)
+    , m_canGrabServer(canGrabServer)
+    , m_defaultVisualId(defaultVisualId)
+    , m_primaryScreenNumber(primaryScreenNumber)
+    , m_displayName(displayName)
+    , m_nativeInterface(nativeInterface)
+#if QT_CONFIG(xcb_xlib)
+    , m_xlib_display(xlibDisplay)
+#endif
+{
     m_reader = new QXcbEventReader(this);
     m_reader->start();
 
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