On Mon, Feb 24, 2020 at 09:56:41PM +0100, Enrico Forestieri wrote:
> On Mon, Feb 24, 2020 at 02:02:32PM -0500, Scott Kostyshak wrote:
> > On Mon, Feb 24, 2020 at 06:39:25PM +0100, Enrico Forestieri wrote:
> > > On Mon, Feb 24, 2020 at 11:05:51AM -0500, Scott Kostyshak wrote:
> > > >
> > > > Apparently another approach would be to add the following:
> > > >
> > > > memset(&padded_event, 0, sizeof(padded_event));
> > > >
> > > > Valgrind does not complain when this line is added to the union patch.
> > >
> > > I am baffled. The last suggestion I have is trying
> > >
> > > alignas(32) xcb_selection_notify_event_t nev = {0};
> >
> > Valgrind still gives the error. I attach the full Valgrind log.
>
> Sigh. The final attempt would be doing the same as it is done in Qt:
>
> struct alignas(32) padded_event
> : xcb_selection_notify_event_t {};
> padded_event nev = {};
>
> If also this fails, I give up.
It works! Please commit since I have no idea what is going on in this
patch. In case it saves you time, attached is the diff and here's a
commit message you can correct:
Cleaner fix to ensure 32-bit XCB events
This fix still satisfies Valgrind and is cleaner than the approach
at 19c41bd0: instead of using calloc we now use the C++11 specifier
alignas. For more info, see the following ML thread:
https://www.mail-archive.com/search?l=mid&q=20200219024908.5n4x4osni55gylo3%40tallinn
Thanks for the patch. Although this was frustrating for you, the
non-valgrind-waiting part was fun for me since I got to learn a little
bit more about memory and initialization.
Scott
diff --git a/src/frontends/qt/GuiApplication.cpp b/src/frontends/qt/GuiApplication.cpp index 2cdd5f6e3b..f665ae28f1 100644 --- a/src/frontends/qt/GuiApplication.cpp +++ b/src/frontends/qt/GuiApplication.cpp @@ -3356,22 +3356,21 @@ bool GuiApplication::nativeEventFilter(const QByteArray & eventType, // It is expected that every X11 event is 32 bytes long, // even if not all 32 bytes are needed. See: // https://www.x.org/releases/current/doc/man/man3/xcb_send_event.3.xhtml - // TODO switch to Q_DECLARE_XCB_EVENT(event, xcb_selection_notify_event_t) - // once we require qt >= 5.6.3 or just copy the macro def. - xcb_selection_notify_event_t *nev = (xcb_selection_notify_event_t*) calloc(32, 1); - - nev->response_type = XCB_SELECTION_NOTIFY; - nev->requestor = srev->requestor; - nev->selection = srev->selection; - nev->target = srev->target; - nev->property = XCB_NONE; - nev->time = XCB_CURRENT_TIME; + struct alignas(32) padded_event + : xcb_selection_notify_event_t {}; + padded_event nev = {}; + + nev.response_type = XCB_SELECTION_NOTIFY; + nev.requestor = srev->requestor; + nev.selection = srev->selection; + nev.target = srev->target; + nev.property = XCB_NONE; + nev.time = XCB_CURRENT_TIME; xcb_connection_t * con = QX11Info::connection(); xcb_send_event(con, 0, srev->requestor, XCB_EVENT_MASK_NO_EVENT, - reinterpret_cast<char const *>(nev)); + reinterpret_cast<char const *>(&nev)); xcb_flush(con); - free(nev); #endif return true; }
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