bug#13262: 24.3.50; crash when multibyte directory name completion.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 24 Dec 2012 23:20:23 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: yfb02119@nifty.com, 13262@debbugs.gnu.org
> 
> > Date: Mon, 24 Dec 2012 19:21:10 +0100
> > From: martin rudalics <rudalics@gmx.at>
> > 
> >  > Sorry, the changes touch quite a few places, but they all had the same
> >  > problem: unwarranted assumptions that input Lisp strings passed to
> >  > primitives are multibyte.  The crash happened because file completion
> >  > calls directory-file-name with a unibyte string (an encoded file
> >  > name).  A similar mess was found and fixed in file-name-directory and
> >  > in expand-file-name.
> > 
> > There's a crash I can reproduce easily but only randomly with my setup
> > and not with emacs -Q (backtrace with actual trunk).  Can it be related?
> 
> No.  The changes were all made in functions that manipulate file
> names, not something even remotely related to redisplay.
> 
> Any chance of a recipe?  Also, what data causes the crash?

Better file a new bug report, btw.

Also, does this buffer position make sense?

  Program received signal SIGSEGV, Segmentation fault.
  0x0107160b in FETCH_MULTIBYTE_CHAR (pos=54295370) at buffer.h:1168
                                      ^^^^^^^^^^^^

Were you indeed editing a 54MB buffer?