Check for the clipboard manager when looping due to app quiting

One can be extremely unlucky and on session logout get this:
 * All apps are going down
 * A Qt app checks if the clipboard manager is there to yield its clipboard contents
   * The clipboard manager is still there
 * Then just after that check, the clipboard manager finishes because of the session end
 * This means the Qt app will loop for 5 seconds trying to yield its clipboard contents
   to a clipboard manager that is not there anymore

Change-Id: Ia89670d4deb72f12e660a0d7aa5b2d212955d6fe
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

1 files changed, 12 insertions, 2 deletions

diff --git a/src/plugins/platforms/xcb/qxcbclipboard.cpp b/src/plugins/platforms/xcb/qxcbclipboard.cpp
index 3c3469a73b..24de78861f 100644
--- a/src/plugins/platforms/xcb/qxcbclipboard.cpp
+++ b/src/plugins/platforms/xcb/qxcbclipboard.cpp
@@ -208,7 +208,7 @@ QXcbClipboard::~QXcbClipboard()
             connection()->sync();
 
             // waiting until the clipboard manager fetches the content.
-            if (!waitForClipboardEvent(m_owner, XCB_SELECTION_NOTIFY, 5000)) {
+            if (!waitForClipboardEvent(m_owner, XCB_SELECTION_NOTIFY, 5000, true)) {
                 qWarning("QClipboard: Unable to receive an event from the "
                          "clipboard manager in a reasonable time");
             }
@@ -726,7 +726,7 @@ namespace
     };
 }
 
-xcb_generic_event_t *QXcbClipboard::waitForClipboardEvent(xcb_window_t win, int type, int timeout)
+xcb_generic_event_t *QXcbClipboard::waitForClipboardEvent(xcb_window_t win, int type, int timeout, bool checkManager)
 {
     QElapsedTimer timer;
     timer.start();
@@ -736,6 +736,16 @@ xcb_generic_event_t *QXcbClipboard::waitForClipboardEvent(xcb_window_t win, int
         if (e)
             return e;
 
+        if (checkManager) {
+            xcb_get_selection_owner_cookie_t cookie = xcb_get_selection_owner(xcb_connection(), atom(QXcbAtom::CLIPBOARD_MANAGER));
+            xcb_get_selection_owner_reply_t *reply = xcb_get_selection_owner_reply(xcb_connection(), cookie, 0);
+            if (!reply || reply->owner == XCB_NONE) {
+                free(reply);
+                return 0;
+            }
+            free(reply);
+        }
+
         // process other clipboard events, since someone is probably requesting data from us
         ClipboardEvent clipboard(connection());
         e = connection()->checkEvent(clipboard);