[PATCH] xcb: add a timeout control when reading INCR property

For the first call of QXcbClipboard::clipboardReadProperty()
inside of clipboardReadIncrementalProperty() in getSelection(),
it will get a XCB_NONE reply before the contents arrived via
property change. Then we give a chance to read more.

Manually tested with following setups:
* examples/widgets/mainwindows/application with gvim(gtk3)
* examples/widgets/widgets/imageviewer with GIMP 2.10.18(based on
gtk2) and GIMP 2.99.6(based on gtk3 via flatpak)

Fixes: QTBUG-56595
Pick-to: 5.12 5.15 6.1 6.2
Done-With: JiDe Zhang <zhangjide@uniontech.com>
Change-Id: Ib45f08464d39ad79137b1da99808c89b7dca2d08
Reviewed-by: JiDe Zhang <zhangjide@uniontech.com>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Gbp-Pq: Name xcb_add_a_timeout_control_when_reading_INCR_property.diff

diff --git a/src/plugins/platforms/xcb/qxcbclipboard.cpp b/src/plugins/platforms/xcb/qxcbclipboard.cpp
index 0a4d675606eee27ed5e3b41e187ecbbcbdd0f809..dabdfcb6c5bd3bcc7dd13825163866534c647e4c 100644 (file)
--- a/src/plugins/platforms/xcb/qxcbclipboard.cpp
+++ b/src/plugins/platforms/xcb/qxcbclipboard.cpp
@@ -835,6 +835,8 @@ QByteArray QXcbClipboard::clipboardReadIncrementalProperty(xcb_window_t win, xcb
         alloc_error = buf.size() != nbytes+1;
     }
 
+    QElapsedTimer timer;
+    timer.start();
     for (;;) {
         connection()->flush();
         xcb_generic_event_t *ge = waitForClipboardEvent(win, XCB_PROPERTY_NOTIFY);
@@ -870,9 +872,11 @@ QByteArray QXcbClipboard::clipboardReadIncrementalProperty(xcb_window_t win, xcb
                 tmp_buf.resize(0);
                 offset += length;
             }
-        } else {
-            break;
         }
+
+        const auto elapsed = timer.elapsed();
+        if (elapsed > clipboard_timeout)
+            break;
     }
 
     // timed out ... create a new requestor window, otherwise the requestor