Running gnome-shell under valgrind, I saw the attached invalid write.
Basically we can destroy a window during event processing, and the old
window_remove_filters simply called g_free() on the filter, ignoring
the refcount. Then later in event processing we call filter->refcount--,
which is writing to free()d memory.
Fix this by centralizing list mutation and refcount handling inside
a new shared _gdk_window_filter_unref() function, and using that
everywhere.
==13876== Invalid write of size 4
==13876== at 0x446B181: gdk_event_apply_filters (gdkeventsource.c:86)
==13876== by 0x446B411: _gdk_events_queue (gdkeventsource.c:188)
==13876== by 0x44437EF: gdk_display_get_event (gdkdisplay.c:410)
==13876== by 0x446B009: gdk_event_source_dispatch (gdkeventsource.c:317)
==13876== by 0x4AB7159: g_main_context_dispatch (gmain.c:2436)
==13876== by 0x4AB7957: g_main_context_iterate.clone.5 (gmain.c:3087)
==13876== by 0x4AB806A: g_main_loop_run (gmain.c:3295)
==13876== by 0x8084D6B: main (main.c:722)
==13876== Address 0x1658bcac is 12 bytes inside a block of size 16 free'd
==13876== at 0x4005EAD: free (vg_replace_malloc.c:366)
==13876== by 0x4ABE515: g_free (gmem.c:263)
==13876== by 0x444BCC9: window_remove_filters (gdkwindow.c:1873)
==13876== by 0x4454BA3: _gdk_window_destroy_hierarchy (gdkwindow.c:2043)
==13876== by 0x447BF6E: gdk_window_destroy_notify (gdkwindow-x11.c:1115)
==13876== by 0x43588E2: _gtk_socket_windowing_filter_func (gtksocket-x11.c:518)
==13876== by 0x446B170: gdk_event_apply_filters (gdkeventsource.c:79)
==13876== by 0x446B411: _gdk_events_queue (gdkeventsource.c:188)
==13876== by 0x44437EF: gdk_display_get_event (gdkdisplay.c:410)
==13876== by 0x446B009: gdk_event_source_dispatch (gdkeventsource.c:317)
==13876== by 0x4AB7159: g_main_context_dispatch (gmain.c:2436)
==13876== by 0x4AB7957: g_main_context_iterate.clone.5 (gmain.c:3087)
https://bugzilla.gnome.org/show_bug.cgi?id=637464
The old functions to get core pointer and devices list are gone as
well. This slice is entirely replaced internally by multidevice
handling and may just go.
The xi2 device manager now handles slaves being detached and/or
attached to a master.
gdk_device_list_slaves() has been added so it is possible to
know how slaves relate with masters. The other backends (X11 and not)
don't neeed to to anything special here since their hierarchy is
fully flat.
When the slave device changes, the master takes the shape of the
new one, modifying its axes, this signal is more useful to catch
this situation than the n-axes property
This function may be used to know the hardware device that triggered
an event, it could resort to the master device in the few cases there's
not a direct hardware device to relate to the event (i.e.: crossing events
due to grabs)
gdk_enable_multidevice() has been replaced with gdk_disable_multidevice(),
so applications may call that function if they want to go back at the
previous behavior.
There would be usually little reasons to call that function, unless the
application is doing X calls itself that count on old fashioned core
devices.
Scanner doesn't detect this case correctly because it's a typedef;
work around it here by explicitly specifying that it's caller
allocates. See bug 636393 for the scanner issue.
One less magic function. Also refactored it to make it easier to
implement. It now returns TRUE if it beeped and FALSE if it failed to do
so. A default implementation exists that just returns FALSE for all the
backends that can't beep windows (read: everything but X11 with XKB -
and why on earth do keyboard libs implement beeping?)
Trying to get rid of all the _gdk_windowing_something() functions that
we expect backends to magically know about and instead put them in a
proper interface (mostly GdkWindowImplClass).
