From: Eli Zaretskii <eliz@gnu.org>
To: Ami Fischman <ami@fischman.org>
Cc: 12745@debbugs.gnu.org
Subject: bug#12745: crash in bidi_pop_it during (idle) redisplay
Date: Sun, 28 Oct 2012 21:50:26 +0200 [thread overview]
Message-ID: <83fw4y8jgd.fsf@gnu.org> (raw)
In-Reply-To: <CAGKqTXUAQAkY5G=EGG4N2NHS8AX3H-Y+1wxSDPmsBw_5GRLEiw@mail.gmail.com>
> Date: Sun, 28 Oct 2012 12:00:49 -0700
> From: Ami Fischman <ami@fischman.org>
> Cc: 12745@debbugs.gnu.org
>
> > Thanks. But I'd like to see the report from your normal session,
> > invoked just as you invoke those that crash.
> >
>
> Of course now I don't have such a session b/c I'm running w/ git HEAD :)
If it loads the same .emacs, that is good enough.
> So this seems to say that there's at least one overlay string at
> > buffer position 1295. Is that reasonable? What was the current
> > buffer when this crashed? You can find that out by typing this at GDB
> > prompt:
> > (gdb) pp current_buffer->name_
> >
>
> (gdb) pp current_buffer->name_
> Cannot access memory at address 0x8b6a00
How about this:
(gdb) p current_buffer->name_
(gdb) xtype
(Note: "p", not "pp".)
If the last command says it's a Lisp string, display the contents of
'struct Lisp_String' whose address it shows.
> > (gdb) p current_buffer->text->beg[1200]@100
> >
>
> (gdb) p current_buffer->text->beg[1200]@100
> $1 = "num to avoid later static_cast in\n// PluginInstance.\nenum
> MediaKeyError {\n kUnknownError = 1,\n kCl"
> which tells me the current buffer was an edited version of
> http://src.chromium.org/viewvc/chrome/trunk/src/webkit/media/crypto/ppapi/cdm_wrapper.cc?view=markup(which
Did that buffer have any minor mode or some other optional feature
turned on, in addition to C++ Mode?
> FWIW, there's nothing non-7-bit-ascii in this file, and nothing that
> should have triggered any bidi-specific logic. It's just a cc-mode
> C++ file.
This crash is not about bidi. It is about handling overlays. That it
barfs inside a function whose name begins with "bidi" is just sheer
luck--or lack thereof.
> Possibly interestingly, if I print p current_buffer->text->beg[0]@100000 to
> emit the entire buffer, I see this text starting at char 1675:
> http://go", '\000' <repeats 2000 times>, "/b
> Those 2000 NULs are definitely out of place (the URL should have started
> with http://go/b) but I don't know if that's a debugging artifact, or what.
This could be the gap, you should see its position and size like this:
(gdb) p current_buffer->text->gpt
(gdb) p current_buffer->text->gap_size
> If I load the modified buffer into my HEAD session (overlays-at 1295)
> returns nil.
That's what I suspected, this is the reason for the abort: Emacs
thinks there's an overlay string at that position, when there is none,
actually.
> > (gdb) frame 6
>
> > #6 0x0000000000447aa1 in pop_it (it=0x7fff2251f1e0) at xdisp.c:5769
>
> > 5769 bidi_pop_it (&it->bidi_it);
>
> > (gdb) pgrowx it->glyph_row
> You can't do that without a process to debug.
So are you debugging a core dump?
next prev parent reply other threads:[~2012-10-28 19:50 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-28 3:31 bug#12745: crash in bidi_pop_it during (idle) redisplay Paul Eggert
2012-10-28 7:49 ` Paul Eggert
2012-10-28 7:50 ` Paul Eggert
2012-10-28 17:23 ` Eli Zaretskii
2012-10-28 19:00 ` Ami Fischman
2012-10-28 19:50 ` Eli Zaretskii [this message]
2012-10-29 4:26 ` Ami Fischman
2012-10-29 17:11 ` Eli Zaretskii
2012-10-29 17:56 ` Ami Fischman
2012-10-29 18:10 ` Eli Zaretskii
2012-10-29 18:29 ` Ami Fischman
2012-10-29 18:55 ` Eli Zaretskii
2012-10-29 18:56 ` Alp Aker
2012-10-29 19:09 ` Alp Aker
2012-10-29 19:23 ` Ami Fischman
2012-10-29 20:24 ` Eli Zaretskii
2012-10-29 20:57 ` Eli Zaretskii
2012-10-29 21:08 ` Ami Fischman
2012-10-30 17:52 ` Eli Zaretskii
2012-10-30 18:29 ` Ami Fischman
2012-10-30 21:00 ` Eli Zaretskii
2012-10-30 21:08 ` Ami Fischman
2012-10-31 15:46 ` Eli Zaretskii
2012-11-01 22:25 ` Ami Fischman
2012-11-02 7:17 ` Eli Zaretskii
2012-11-02 7:43 ` Ami Fischman
2012-11-03 9:31 ` Eli Zaretskii
2012-10-29 20:25 ` Eli Zaretskii
2012-10-29 20:42 ` Alp Aker
2012-10-29 20:59 ` Eli Zaretskii
2012-10-29 21:25 ` Alp Aker
2012-10-29 21:53 ` Alp Aker
2012-11-23 20:14 ` Ami Fischman
2012-11-23 21:56 ` Eli Zaretskii
2012-11-25 4:52 ` Ami Fischman
2012-11-25 16:51 ` Eli Zaretskii
2013-02-10 3:07 ` Glenn Morris
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