Subject: RE: bug#18516: Acknowledgement (24.4.50; EMACS crashes when I try to open Elisp manual)

From: Vincent Belaïche <[email-masked]>
Date: Mon, 22 Sep 2014 19:13:54 +0200

Дорогие Дмитрий, Илья, и другие,

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> Date: Mon, 22 Sep 2014 17:39:36 +0300
> From: [email-masked]
> Subject: Re: bug#18516: Acknowledgement (24.4.50; EMACS crashes when I try to open Elisp manual)
> To: [email-masked]
> CC: [email-masked]; [email-masked]
>
> > Date: Mon, 22 Sep 2014 10:21:57 +0400
> > From: Dmitry Antipov <[email-masked]>
> > CC: [email-masked], Eli Zaretskii <[email-masked]>
> >
> > On 09/22/2014 08:21 AM, Vincent Belaïche wrote:
> >
> > > Here is attached the log of the gdb sessione encoded in raw-text coding
> > > system, please feel free to ask me for any further step --- like setting
> > > break points, dumping some variable contents, and so on --- if it can
> > > help locate the problem.
> >
> > Crash in Fexpand_file_name? Hm...there was some changes in r11780[123]
> > and r117806. Can you try to revert to r117800 and reproduce this crash?
>
> This was introduced in r117806 (alloca doesn't like negative arguments).
>
> Fixed in trunk revision 117918.

Could you please send to me the exact bzr command you would like me to
do in order to revert to whatever revision you think is of interest, and
then I can rebuild Emacs and try again to crash.

Another option would be to instrument Fexpand_file_name in order to find
when it crashes in more details, just send me a fileio.c as attachment
if you want me to do that.

After reading of Eli that the crash is within Fexpand_file_name, I have
done some more investigation how to provoke the crash with a simpler
command line, and I have found that the following arguments suffice:

-Q "--eval=(expand-file-name \"c:Invalid/path/info\" \"C:\\Programme\\GNU\\installation\\emacs-install\\emacs\\trunk\\src/\")"

Please note that:

1) C:\Programme\GNU\installation\emacs-install\emacs\trunk\src/ is the
   value of variable default-directory, and I need to pass it explicitly
   to expand-file-name for the crash to happen

2) It is on purpose that
   C:\Programme\GNU\installation\emacs-install\emacs\trunk\src/ mixes
   backward and forward slashes, it is the way it is when I launch Emacs
   with -Q and
   current directory=C:\Programme\GNU\installation\emacs-install\emacs\trunk\src

3) C:\Programme\GNU\installation\emacs-install\emacs\trunk\src is the
   directory where the C source code is found, and in which I lauch gdb
   according to Eli's recommendation.

4) c:Invalid/path/info is an invalid path, and it is on purpose that
   first slash after c: is missing.

Hopefully, this shorter settup will allow you to reproduce the
crash. Could you please try that before I have to do any bzr reverting.

VBR,
  Vincent.

PS: Attached is a gdb session log with the crash causing simpler settup.