Emacs-24 Hangs When Displaying Unicode #x6c0 (ARABIC HEH WITH YEH ABOVE)

Emacs-24 Hangs When Displaying Unicode #x6c0 (ARABIC HEH WITH YEH ABOVE)

[Mohsen BANAN]

Emacs-24 hangs when displaying unicode #x6c0
(arabic heh with yeh above) -- at least in my
environments. The display hangs but the emacs process
stays alive.

Before trying to reproduce the problem, save all
your buffers.

You can reproduce the problem by eval-ing
    (ucs-insert 1728)

I am not including the actual character; as a whole
lot of people would likely be unhappy if I did.

This problem is reproducible in all my
environments Debian and Ubuntu emacs-24.0.50 through
emacs-24.0.90.4.

I have looked some into this problematic character.

On emacs23, describe-char on that character produces:

    character: (1728, #o3300, #x6c0)
preferred charset: unicode (Unicode (ISO10646))
       code point: 0x06C0
           syntax: w 	which means: word
         category: .:Base, b:Arabic
      buffer code: #xDB #x80
        file code: #xDB #x80 (encoded by coding system utf-8-unix)
          display: by this font (glyph code)
    xft:-unknown-B Compset-normal-normal-normal-*-13-*-*-*-*-0-iso10646-1 (#xC7)

Character code properties: customize what to show
  name: ARABIC LETTER HEH WITH YEH ABOVE
  old-name: ARABIC LETTER HAMZAH ON HA
  general-category: Lo (Letter, Other)
  decomposition: (1749 1620)

According to isiri-6219, in Persian it is a
forbiden character. In other words persian input
methods should not produce this character --
because it can be produced by 1749+1620.

But, Microsoft does produce that character. So, I
have been receiving various emails that were/are
hanging my emacs display. It took a while to
narrow it down to this character.

If this problem is not specific to my
environement, then perhaps we should also look for
other problematic characters.

Perhaps we can have a buffer that contains all
unicode characters and have the display go through it
all as a regression tester.

Please let me know if this problem is reproducible in your
environements.

Thanks.

...Mohsen

Re: Emacs-24 Hangs When Displaying Unicode #x6c0 (ARABIC HEH WITH YEH ABOVE)

[Antoine Levitt]

06/03/12 19:33, Mohsen BANAN
> Emacs-24 hangs when displaying unicode #x6c0
> (arabic heh with yeh above) -- at least in my
> environments. The display hangs but the emacs process
> stays alive.
>
> Before trying to reproduce the problem, save all
> your buffers.
>
> You can reproduce the problem by eval-ing
>     (ucs-insert 1728)

Hi,

I'm not able to reproduce this bug, both in my environment (which has
bidi-display-reordering nil), and in emacs -Q. Can you post a recipe to
reproduce this from emacs -Q ?

Antoine

Re: Emacs-24 Hangs When Displaying Unicode #x6c0 (ARABIC HEH WITH YEH ABOVE)

[Mohsen BANAN]

>>>>> On Tue, 06 Mar 2012 20:09:04 +0100, Antoine Levitt <antoine.levitt@gmail.com> said:

  Antoine> 06/03/12 19:33, Mohsen BANAN
  >> You can reproduce the problem by eval-ing
  >> (ucs-insert 1728)

  Antoine> I'm not able to reproduce this bug, both in my environment (which has
  Antoine> bidi-display-reordering nil), and in emacs -Q. Can you post a recipe to
  Antoine> reproduce this from emacs -Q ?

In my environment,

- I run emacs -Q
- Then in the *scratch* buffer I eval (ucs-insert 1728)

Emacs display hangs.

I don't think this bug is necessarily bidi
related. Fonts, X and display engine are likely
more relevant.

Anybody else is seeing this bug?

...Mohsen

Re: Emacs-24 Hangs When Displaying Unicode #x6c0 (ARABIC HEH WITH YEH ABOVE)

[Eli Zaretskii]

> From: Mohsen BANAN <list-general@mohsen.1.banan.byname.net>
> Date: Tue, 06 Mar 2012 13:37:16 -0800
> 
> In my environment,
> 
> - I run emacs -Q
> - Then in the *scratch* buffer I eval (ucs-insert 1728)
> 
> Emacs display hangs.
> 
> I don't think this bug is necessarily bidi
> related. Fonts, X and display engine are likely
> more relevant.
> 
> Anybody else is seeing this bug?

I don't, FWIW.

When this happens, can you attach a debugger and show the backtrace?

Btw, I think it is best to continue this discussion as part of a bug
report, so please "M-x report-emacs-bug RET" with the details.

Thanks.

Re: Emacs-24 Hangs When Displaying Unicode #x6c0 (ARABIC HEH WITH YEH ABOVE)

[Mohsen BANAN]

>>>>> On Wed, 07 Mar 2012 05:55:28 +0200, Eli Zaretskii <eliz@gnu.org> said:

  Mohsen> Emacs display hangs.
  Mohsen> 
  Mohsen> I don't think this bug is necessarily bidi
  Mohsen> related. Fonts, X and display engine are likely
  Mohsen> more relevant.
  Mohsen> 
  Mohsen> Anybody else is seeing this bug?

  Eli> I don't, FWIW.

  Eli> When this happens, can you attach a debugger and show the backtrace?

I don't get a core dump. The display hangs and the
emacs process keeps running. I don't think a gdb
backtrace is possible in this case.

I can run emacs under strace and capture that.

  Eli> Btw, I think it is best to continue this discussion as part of a bug
  Eli> report, so please "M-x report-emacs-bug RET" with the details.

I shall do so.

Thanks.

...Mohsen

Re: Emacs-24 Hangs When Displaying Unicode #x6c0 (ARABIC HEH WITH YEH ABOVE)

[Eli Zaretskii]

> From: Mohsen BANAN <list-general@mohsen.1.banan.byname.net>
> Date: Wed, 07 Mar 2012 13:10:24 -0800
> 
>   Eli> When this happens, can you attach a debugger and show the backtrace?
> 
> I don't get a core dump. The display hangs and the
> emacs process keeps running. I don't think a gdb
> backtrace is possible in this case.

It's possible.  When you attach GDB to a running program, that program
is stopped in its tracks, and the backtrace will show where it was
stuck and what it was doing.

> I can run emacs under strace and capture that.

That's much less useful than a backtrace, so please try attaching the
debugger first.

>   Eli> Btw, I think it is best to continue this discussion as part of a bug
>   Eli> report, so please "M-x report-emacs-bug RET" with the details.
> 
> I shall do so.

Thanks.