Prevent potential crash in QXcbCursor::queryPointer().

xcb_get_setup might return 0, but we already have it in QXcbConnection.

Task-number: QTBUG-27686
Change-Id: I58418aedd6bc121ae2b9605389beb3f6612d7fb7
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Gatis Paeglis <gatis.paeglis@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

3 files changed, 11 insertions, 12 deletions

diff --git a/src/plugins/platforms/xcb/qxcbcursor.cpp b/src/plugins/platforms/xcb/qxcbcursor.cpp
index 0510c1db5b..c1cfbd02d6 100644
--- a/src/plugins/platforms/xcb/qxcbcursor.cpp
+++ b/src/plugins/platforms/xcb/qxcbcursor.cpp
@@ -508,16 +508,16 @@ xcb_cursor_t QXcbCursor::createBitmapCursor(QCursor *cursor)
     return c;
 }
 
-void QXcbCursor::queryPointer(xcb_connection_t *conn, xcb_window_t *rootWin, QPoint *pos, int *keybMask)
+void QXcbCursor::queryPointer(QXcbConnection *c, xcb_window_t *rootWin, QPoint *pos, int *keybMask)
 {
     if (pos)
         *pos = QPoint();
-    xcb_screen_iterator_t it = xcb_setup_roots_iterator(xcb_get_setup(conn));
+    xcb_screen_iterator_t it = xcb_setup_roots_iterator(c->setup());
     while (it.rem) {
         xcb_window_t root = it.data->root;
-        xcb_query_pointer_cookie_t cookie = xcb_query_pointer(conn, root);
+        xcb_query_pointer_cookie_t cookie = xcb_query_pointer(c->xcb_connection(), root);
         xcb_generic_error_t *err = 0;
-        xcb_query_pointer_reply_t *reply = xcb_query_pointer_reply(conn, cookie, &err);
+        xcb_query_pointer_reply_t *reply = xcb_query_pointer_reply(c->xcb_connection(), cookie, &err);
         if (!err && reply) {
             if (pos)
                 *pos = QPoint(reply->root_x, reply->root_y);
@@ -537,17 +537,16 @@ void QXcbCursor::queryPointer(xcb_connection_t *conn, xcb_window_t *rootWin, QPo
 QPoint QXcbCursor::pos() const
 {
     QPoint p;
-    queryPointer(xcb_connection(), 0, &p);
+    queryPointer(connection(), 0, &p);
     return p;
 }
 
 void QXcbCursor::setPos(const QPoint &pos)
 {
-    xcb_connection_t *conn = xcb_connection();
     xcb_window_t root;
-    queryPointer(conn, &root, 0);
-    xcb_warp_pointer(conn, XCB_NONE, root, 0, 0, 0, 0, pos.x(), pos.y());
-    xcb_flush(conn);
+    queryPointer(connection(), &root, 0);
+    xcb_warp_pointer(xcb_connection(), XCB_NONE, root, 0, 0, 0, 0, pos.x(), pos.y());
+    xcb_flush(xcb_connection());
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/xcb/qxcbcursor.h b/src/plugins/platforms/xcb/qxcbcursor.h
index 9726c5955a..4c74034988 100644
--- a/src/plugins/platforms/xcb/qxcbcursor.h
+++ b/src/plugins/platforms/xcb/qxcbcursor.h
@@ -56,7 +56,7 @@ public:
     QPoint pos() const;
     void setPos(const QPoint &pos);
 
-    static void queryPointer(xcb_connection_t *conn, xcb_window_t *rootWin, QPoint *pos, int *keybMask = 0);
+    static void queryPointer(QXcbConnection *c, xcb_window_t *rootWin, QPoint *pos, int *keybMask = 0);
 
 private:
     xcb_cursor_t createFontCursor(int cshape);
diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index 5170ff9e10..a46d51127f 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -275,8 +275,8 @@ QPlatformServices *QXcbIntegration::services() const
 Qt::KeyboardModifiers QXcbIntegration::queryKeyboardModifiers() const
 {
     int keybMask = 0;
-    QXcbConnection* conn = m_connections.at(0);
-    QXcbCursor::queryPointer(conn->xcb_connection(), 0, 0, &keybMask);
+    QXcbConnection *conn = m_connections.at(0);
+    QXcbCursor::queryPointer(conn, 0, 0, &keybMask);
     return conn->keyboard()->translateModifiers(keybMask);
 }