bug#28430: 26.0.50; Segfault on unexpected connection loss

[Eli Zaretskii <eliz@gnu.org>]

> From: Daniel Kraus <daniel@kraus.my>
> Cc: 28430@debbugs.gnu.org
> Date: Wed, 13 Sep 2017 17:12:14 +0800
> 
> >> Open new buffer (e.g. 'test.rest') and `M-x restclient-mode`.
> >> Type:
> >> `GET http://127.0.0.1:6543/`
> >> and then press `C-c C-c`
> >>
> >> Switch to the netcat window and Ctrl-C to break up the connection.
> >> Emacs segfaults:
> >> #+BEGIN_QUOTE
> >> Fatal error 11: Segmentation fault
> >
> > Can you please run this under GDB, and when Emacs segfaults, produce
> > the C backtrace and post it here?
> 
> --cut--
> #0  0x00007ffff017bc40 in raise () at /usr/lib/libpthread.so.0
> #1  0x0000000000597ab9 in terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:394
> #2  0x0000000000632a74 in die (msg=0x778761 "CONSP (data)", file=0x7786d1 "keyboard.c", line=999) at alloc.c:7419
> #3  0x000000000059c3e1 in cmd_error_internal (data=..., context=0x798c6c "error in process sentinel: ") at keyboard.c:999
> #4  0x00000000006c5edd in exec_sentinel_error_handler (error_val=...) at process.c:7105
> #5  0x0000000000657d51 in internal_condition_case_1 (bfun=0x6c2b0d <read_process_output_call>, arg=..., handlers=..., hfun=0x6c5ebe <exec_sentinel_error_handler>) at eval.c:1352
> #6  0x00000000006c609c in exec_sentinel (proc=..., reason=...) at process.c:7158
> #7  0x00000000006c6303 in status_notify (deleting_process=0x0, wait_proc=0x0) at process.c:7260

Thanks.  This seems to be a slightly different problem: the signal
here is 6 (SIGABRT), not SIGSEGV.

In any case, can you show what these GDB commands produce, after the
crash is triggered, and you wind up in 'raise'?

 (gdb) frame 4
 (gdb) pp error_val

After "frame 4", you should be in this function:

   #4  0x00000000006c5edd in exec_sentinel_error_handler (error_val=...) at process.c:7105

If not, adjust the argument 4 as needed.