Re: [gtk-osx-users] crash on updateTrackingRect is BAAACK

[Allin Cottrell <cottrell wfu edu>]

On Tue, 17 Nov 2020, John Ralls wrote:

> > On Nov 17, 2020, at 7:52 AM, Allin Cottrell <cottrell wfu edu> wrote:
> >
> > On Mon, 16 Nov 2020, John Ralls wrote:
> >
> > > > On Nov 16, 2020, at 1:46 PM, Allin Cottrell via gtk-osx-users-list <gtk-osx-users-list gnome org> wrote:
> > > >
> > > > Back in 2106 there was a thread concerning a crash on macOS when (a) a GTK window is maximized, then (b) the user tries 
> > > > to close the maximized window via the quartz control button ("x"). See
> > > > https://mail.gnome.org/archives/gtk-osx-users-list/2016-February/msg00005.html
> > > > and following.
> > > >
> > > > I thought we were done with that; there seemed to be fix in hand and no more was heard of the problem. But 
> > > > now I'm seeing the same thing again -- this is with GTK 2.24.32 on macOS 10.15.7. The crash report from the 
> > > > OS looks just like before, with the coup de grace in this sequence:
> > > >
> > > > Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
> > > > 0 libgdk-quartz-2.0.0.dylib 0x000000010bb690a5 -[GdkQuartzView updateTrackingRect] + 37
> > > > 1 libgdk-quartz-2.0.0.dylib 0x000000010bb69249 -[GdkQuartzView setFrame:] + 105
> > > > 2 com.apple.AppKit          0x00007fff2d5d889b -[NSThemeFrame setStyleMask:] + 1008
> > > >
> > > > Any ideas on what might have changed to allow this bug to re-emerge?
> > > >
> > > > Just for reference, here's the code for the function at issue, in GdkQuartzView.c. In 2016 the problem was handled by checking for 
> > > > "!impl" as well as "!impl->toplevel" before doing anything substantive. Now apparently that is not 
> > > > sufficient. [...]
> > >
> > > It's probably a use-after-free where private->impl has been freed but not NULLed. Address sanitizer is the 
> > > fastest way to track down problems like that. I haven't been working much with Gtk2 in the last couple of years 
> > > but The GIMP still does. Unfortunately I don't think any of them subscribe here so I suggest you open an issue 
> > > at https://gitlab.gnome.org/GNOME/gtk.
> >
> > John, thanks for forwarding my message to the gnome guys, but Emmanuele's response was kinda what I was expecting 
> > ("You're on your own with GTK 2").
> >
> > However, when we fixed the previous incarnation of this bug, IIRC you also submitted a patch for GTK 3 -- so 
> > perhaps this mutation of the bug also affects GTK 3? That would be interesting to know.
> >
> > I have one thought about taking this further. Last time around we put in a "nullify a pointer" callback for 
> > windowWillClose (in GdkQuartzWindow.c). I wonder if we now need a similar callback for a different event specification. 
> > I'll see what I can figure out.
> >
> > One other point: Do you know if there's any way to disable the maximize control for an application's quartz window? 
> > Current macOS maps this to "Full Screen" (task bar hidden) and there's really no reason for anyone to run my 
> > application in that mode, so blocking or re-mapping the maximize action would be a possible workaround. (The
> > crash seems to be specific to closing a maximized window.)
>
> Allin,
>
> Emmanuel didn't say "you're on your own", he said that time is 
> running out and to get patches in ASAP.
>
> There's a message in there, though: It's past time to migrate your 
> app to Gtk3. Gtk2 might work OK in macOS 11 (I haven't done 
> anything more than cursory does-it-build checks) but Apple has a 
> history of changing their APIs and at some point Gtk2 will stop 
> working on some future version of macOS.

Granted, but I'll cross that bridge when I come to it. GTK 2 works 
fine on macOS 10.15 apart from this one issue.

> This SO suggests one way to prevent full-screen: 
> https://stackoverflow.com/questions/33457029/osx-disable-fullscreen-mode-from-the-zoom-button

Ah, that's very helpful. I've patched gdkwindow-quartz.c, 
_gdk_window_impl_new(), to add

[impl->toplevel 
setCollectionBehavior:NSWindowCollectionBehaviorFullScreenAuxiliary];

for GDK_WINDOW_TOPLEVEL, GDK_WINDOW_DIALOG and GDK_WINDOW_TEMP, and 
my woes are over. The max button now just does "regular" 
maximization rather than full-screen and there's no crash closing a 
maximized window.

> I just tested full-screening and red button closing GnuCash built 
> yesterday with Gtk+-3.24.23 on macOS 11 and run with 
> MallocScribble=1 to make sure that a use-after-free would crash. 
> It closed cleanly, no crash. You might diff GtkNSWindow.c between 
> Gtk2 and Gtk3 to see if there's something helpful there.

GtkNSWindow.c ? I'm not seeing a file of that name (or close) in the 
GTK 2 codebase.

Allin