Re: C-g crash in C-x C-f (OSX Lion)

[Carsten Mattner]

On Sat, Dec 17, 2011 at 9:32 AM, Eli Zaretskii <address@hidden> wrote:
>> From: Andreas Schwab <address@hidden>
>> Cc: Carsten Mattner <address@hidden>, address@hidden
>> Date: Fri, 16 Dec 2011 22:24:26 +0100
>>
>> Eli Zaretskii <address@hidden> writes:
>>
>> > How come the x coordinate of an event could be passed to
>> > ns_string_to_symbol as a string, no matter how it is type-cast??
>>
>> Because Fx_own_selection_internal put it there.
>>
>> (Get your barf bag ready!)
>
> Thanks for the heads-up, I needed that bag.
>
> So the question now is why that string comes out as NULL.  This
> happens in this code in x-own-selection-internal:
>
>  pb =[NSPasteboard pasteboardWithName: symbol_to_nsstring (selection_name)];
>
> and the value of pb gets later put into the event's x member:
>
>  /* XXX An evil hack, but a necessary one I fear XXX */
>  {
>    struct input_event ev;
>    ev.kind = SELECTION_REQUEST_EVENT;
>    ev.modifiers = 0;
>    ev.code = 0;
>    *(EMACS_INT*)(&(ev.x)) = (EMACS_INT)pb; // FIXME: BIG UGLY HACK!!
>    *(EMACS_INT*)(&(ev.y)) = (EMACS_INT)NSStringPboardType;
>    ns_handle_selection_request (&ev);
>  }
>
> Now, this part of the backtrace:
>
>  #4  0x00285202 in Fx_own_selection_internal (selection_name=27744162,
>  selection_value=39954401) at nsselect.m:425
>          ev = {
>            kind = SELECTION_REQUEST_EVENT,
>            code = 0,
>            part = 1771886,
>            modifiers = 0,
>            x = 0,
>            y = -1396380776,
>            timestamp = 1,
>            padding = {0x4, 0x1a6ba22},
>            frame_or_window = 27783754,
>            arg = 27703842
>          }
>          pb = (id) 0x0
>
> indicates that pb comes out as NULL and gets put into ev.x as zero.
> So the question is: what is selection_name, whose value is 27744162,
> and which caused symbol_to_nsstring to return NULL?
>
> Carsten, if you still have the crashed session, please go to the stack
> frame showing the call to Fx_own_selection_internal (in the above
> case, this is frame #4), by typing "frame N" at the GDB prompt (where
> N is the number of the frame), and then type these commands:
>
>  (gdb) p selection_name
>  (gdb) xtype
>
> I expect the last command to say "Lisp_Symbol", in which case please
> type
>
>  (gdb) xsymbol
>
> to show what symbol is that.
>
> If the crashed session is no longer available, make it crash as soon
> as possible and then do the above.

New session same #4 for that call
(gdb) frame 4
#4  0x00285202 in Fx_own_selection_internal (selection_name=27744162,
selection_value=78814449) at nsselect.m:425
425         ns_handle_selection_request (&ev);
Current language:  auto; currently objective-c
(gdb) p selection_name
$1 = 27744162
(gdb) xtype
Undefined command: "xtype".  Try "help".
(gdb) xsymbol
Undefined command: "xsymbol".  Try "help".
(gdb)

Could gdb be too old for xsymbol/xtype commands? Are those aliases?
GNU gdb 6.3.50-20050815 (Apple version gdb-1708) (Mon Aug  8 20:32:45 UTC 2011)
Copyright 2004 Free Software Foundation, Inc.

Apple prefers lldb and I have that ready and also could build
lldb from svn trunk if there's a reason to do so.