Crashes on invalid UngrabAccelerator calls
To reproduce, run this command:
dbus-send --session --dest=org.gnome.Shell --print-reply /org/gnome/Shell org.gnome.Shell.UngrabAccelerator uint32:1234
After that gnome-flashback crashes. Stacktrace:
#0 0x00007f37e10a397a in __strcmp_sse2_unaligned () at ../sysdeps/x86_64/multiarch/strcmp-sse2-unaligned.S:31
#1 0x00007f37e136fca9 in g_str_equal (v1=v1@entry=0x0, v2=<optimized out>) at ../../../../glib/ghash.c:1925
#2 0x000055f4798aac4f in handle_ungrab_accelerator (dbus_shell=0x55f47ac59070, invocation=0x7f37cc023e60 [GDBusMethodInvocation], action=1234, user_data=<optimized out>)
at flashback-shell.c:380
#3 0x00007f37df028fce in ffi_call_unix64 () at ../src/x86/unix64.S:76
#4 0x00007f37df02893f in ffi_call (cif=cif@entry=0x7ffc9c283fa0, fn=fn@entry=0x55f4798aac00 <handle_ungrab_accelerator>, rvalue=<optimized out>, avalue=avalue@entry=0x7ffc9c283ed0)
at ../src/x86/ffi64.c:525
...
#9 0x000055f4798adf0a in _flashback_dbus_shell_skeleton_handle_method_call (connection=<optimized out>, sender=<optimized out>, object_path=<optimized out>, interface_name=0x7f37cc0285a0 "org.gnome.Shell", method_name=0x7f37cc025b50 "UngrabAccelerator", parameters=<optimized out>, invocation=0x7f37cc023e60 [GDBusMethodInvocation], user_data=0x55f47ac59070) at flashback-dbus-shell.c:3014
#10 0x00007f37e157c076 in g_dbus_interface_method_dispatch_helper (interface=<optimized out>, method_call_func=0x55f4798add50 <_flashback_dbus_shell_skeleton_handle_method_call>, invocation=0x7f37cc023e60 [GDBusMethodInvocation]) at ../../../../gio/gdbusinterfaceskeleton.c:609
#11 0x00007f37e1563ebc in call_in_idle_cb (user_data=0x7f37cc023e60) at ../../../../gio/gdbusconnection.c:4842
#12 0x00007f37e1380ae8 in g_main_dispatch (context=0x55f47a74d090) at ../../../../glib/gmain.c:3182
#13 0x00007f37e1380ae8 in g_main_context_dispatch (context=context@entry=0x55f47a74d090) at ../../../../glib/gmain.c:3847
#14 0x00007f37e1380ed8 in g_main_context_iterate (context=0x55f47a74d090, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../../glib/gmain.c:3920
#15 0x00007f37e13811d2 in g_main_loop_run (loop=0x55f47a857040) at ../../../../glib/gmain.c:4116
#16 0x000055f47985bd17 in main (argc=<optimized out>, argv=<optimized out>) at gf-main.c:163