src/ftfont.c problem on SUSE/old fontconfig versions.

src/ftfont.c problem on SUSE/old fontconfig versions.

[Lynbech Christian]

I have stumbled across a possible problem with ftfont.c

I have compiled and installed from the trunk of the git mirror and
trying to run the result on my SUSE SLED 10, patchlevel 1 ended in a
segmentation fault.

Digging down a bit, I found that the segmentation fault happens in a
call to the fontconfig function 'FcPatternGetCharSet' in the line

          if (FcPatternGetCharSet (fontset->fonts[0], FC_CHARSET, 0, &charset)
              == FcResultMatch)

in the function 'ftfont_lookup_cache'. Compiling the same emacs snapshot
on a rather recent Debian unstable installation yielded no such problem.

The version of fontconfig on my SUSE system is apparently 2.3.94 and
when I installed fontconfig 2.6.0 (like on the Debian system) the
segmentation fault went away.

The last time I updated my emacs 23 was June 11. and this version does
not have the segmentation fault problem, but quite a lot has happened to
ftfont.c since then so I have no guess as to what may have been
triggering the problem.

(For the record, I am back in the clear, feel free to ignore the problem
if you prefer.)

------------------------+-----------------------------------------------------
Christian Lynbech       | christian #\@ defun #\. dk
------------------------+-----------------------------------------------------
Hit the philistines three times over the head with the Elisp reference manual.
                                        - petonic@hal.com (Michael A. Petonic)

Re: src/ftfont.c problem on SUSE/old fontconfig versions.

[Kenichi Handa]

In article <ytqpbq0vqxpe.fsf@ul000205.eu.tieto.com>, Lynbech Christian <christian.lynbech@tietoenator.com> writes:

> I have stumbled across a possible problem with ftfont.c
> I have compiled and installed from the trunk of the git mirror and
> trying to run the result on my SUSE SLED 10, patchlevel 1 ended in a
> segmentation fault.

> Digging down a bit, I found that the segmentation fault happens in a
> call to the fontconfig function 'FcPatternGetCharSet' in the line

>           if (FcPatternGetCharSet (fontset->fonts[0], FC_CHARSET, 0, &charset)
>               == FcResultMatch)

> in the function 'ftfont_lookup_cache'. Compiling the same emacs snapshot
> on a rather recent Debian unstable installation yielded no such problem.

> The version of fontconfig on my SUSE system is apparently 2.3.94 and
> when I installed fontconfig 2.6.0 (like on the Debian system) the
> segmentation fault went away.

Then it's apparently the bug of 2.3.94.  I don't see that
problem with fontconfig 2.4.2.

The question is whether or not we can have a workaround of
the problem.  If not, we must add a check for the version of
fontconfig in configure.in.  Could you show me the values of
`fontset' and `fontset->nfont' at the time of crash?

> The last time I updated my emacs 23 was June 11. and this version does
> not have the segmentation fault problem, but quite a lot has happened to
> ftfont.c since then so I have no guess as to what may have been
> triggering the problem.

FYI, that part of code is added on 8th July.

---
Kenichi Handa
handa@ni.aist.go.jp

Re: src/ftfont.c problem on SUSE/old fontconfig versions.

[Glenn Morris]

Kenichi Handa wrote:

> The question is whether or not we can have a workaround of
> the problem.  If not, we must add a check for the version of
> fontconfig in configure.in. 

I draw your attention to this (should probably wait for papers):

http://lists.gnu.org/archive/html/emacs-devel/2008-02/msg01918.html

  From:            Emanuele Giaquinta
  Subject:         Re: configure.in fix
  Date:            Sat, 5 Jul 2008 13:03:42 +0200

Re: src/ftfont.c problem on SUSE/old fontconfig versions.

[Glenn Morris]

Glenn Morris wrote:

> http://lists.gnu.org/archive/html/emacs-devel/2008-02/msg01918.html

Sorry, wrong link:

http://lists.gnu.org/archive/html/emacs-devel/2008-07/msg00114.html