Re: Crash in foreach_window_1 (delete-frame)

[YAMAMOTO Mitsuharu]

>>>>> On Sun, 14 May 2006 13:18:36 +0100, David Reitter <address@hidden> said:

> I had this crash the other day. I had a frame with a Completions
> buffer (lower window in 2-window config.) open, and wanted to delete
> the frame.  Can't reproduce, but maybe someone can tell from looking
> at the stack trace below.

> Exception:  EXC_BAD_ACCESS (0x0001)
> Codes:      KERN_INVALID_ADDRESS (0x0001) at 0x110bc0d0

> 0   org.gnu.AquamacsEmacs             0x0004f5d8 foreach_window_1 + 52  
> (window.c:6818)
> 1   org.gnu.AquamacsEmacs             0x0004f60c foreach_window_1 + 104 
> (window.c:6821)
> 2   org.gnu.AquamacsEmacs             0x0004f60c foreach_window_1 + 104 
> (window.c:6821)
> 3   org.gnu.AquamacsEmacs             0x0004566c window_from_coordinates + 
> 120 (window.c:949)
> 4   org.gnu.AquamacsEmacs             0x0001e3b0 remember_mouse_glyph + 60 
> (xdisp.c:2061)
> 5   org.gnu.AquamacsEmacs             0x0013f83c note_mouse_movement + 332 
> (macterm.c:4321)
> 6   org.gnu.AquamacsEmacs             0x0014780c XTread_socket + 2228 
> (macterm.c:10366)
> 7   org.gnu.AquamacsEmacs             0x00085dc4 read_avail_input + 140 
> (keyboard.c:6751)
> 8   org.gnu.AquamacsEmacs             0x00085fbc handle_async_input + 48 
> (keyboard.c:6898)
> 9   org.gnu.AquamacsEmacs             0x000f175c Fdelq + 280 (fns.c:1724)
> 10  org.gnu.AquamacsEmacs             0x00015ab0 Fdelete_frame + 884 
> (frame.c:1284)

Looks interesting.

frame.c:
  1274    /* Mark all the windows that used to be on FRAME as deleted, and then
  1275       remove the reference to them.  */
  1276    delete_all_subwindows (XWINDOW (f->root_window));
  1277    f->root_window = Qnil;
  1278  
  1279    Vframe_list = Fdelq (frame, Vframe_list);

Fdelete_frame sets f->root_window to Qnil at line 1277.  If it is
interrupted (or read_socket_hook is called by QUIT if SYNC_INPUT is
defined) inside Fdelq, foreach_window might be called through the path
shown in the above backtrace.

window.c:
  6793  void
  6794  foreach_window (f, fn, user_data)
  6795       struct frame *f;
  6796       int (* fn) P_ ((struct window *, void *));
  6797       void *user_data;
  6798  {
  6799    foreach_window_1 (XWINDOW (FRAME_ROOT_WINDOW (f)), fn, user_data);
  6800  }

In such a case, FRAME_ROOT_WINDOW (f) is Qnil and XWINDOW (...) does not
return a valid pointer.

I think this scenario can also happen on X11.  Maybe test WINDOWP
(FRAME_ROOT_WINDOW (f)) before line 6799?

                                     YAMAMOTO Mitsuharu
                                address@hidden