bug#13546: 24.2.92; Error(s) when sending emails

[Eli Zaretskii]

> From: "Sebastien Vauban" <wxhgmqzgwmuf@spammotel.com>
> Date: Fri, 25 Jan 2013 17:03:30 +0100
> 
> > What I'd like is for you to step with a debugger through the affected
> > code and see what is going on there.
> 
> You mean with gdb, like I do when Emacs is hanging or crashing?

Yes.

> > But since your cannot reproduce this at will, it doesn't seem to be
> > possible...
> 
> But I'm sure it will come back[1], and that will happen, can you tell me what 
> I
> should type in the GDB window?

OK.  So please attach GDB to Emacs _before_ the problem happens, and
set a breakpoint like this:

  (gdb) break fileio.c:4913
  (gdb) continue

The breakpoint will be on this line in fileio.c:

  if (! ok)
    error ("IO error writing %s: %s", SDATA (filename),  <<<<<<<<<
           emacs_strerror (save_errno));

Then do whatever it takes to reproduce the problem.  When it happens
again, this breakpoint should break.  Then type the following GDB
commands:

  (gdb) p desc
  (gdb) p/x fd_info[N].flags

where N is the value of 'desc' as displayed by "p desc".  That's
assuming that value is non-negative; if it is negative, the second
command is not going to display anything useful.

Meanwhile, I installed a couple of small changes that may or may not
solve this problem, so please be sure to try the next pretest binary
when it becomes available.

Thanks.