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bug#12745: crash in bidi_pop_it during (idle) redisplay
From: |
Eli Zaretskii |
Subject: |
bug#12745: crash in bidi_pop_it during (idle) redisplay |
Date: |
Sun, 28 Oct 2012 21:50:26 +0200 |
> 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?
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Paul Eggert, 2012/10/27
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Paul Eggert, 2012/10/28
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Paul Eggert, 2012/10/28
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Eli Zaretskii, 2012/10/28
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Ami Fischman, 2012/10/28
- bug#12745: crash in bidi_pop_it during (idle) redisplay,
Eli Zaretskii <=
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Ami Fischman, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Eli Zaretskii, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Ami Fischman, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Eli Zaretskii, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Ami Fischman, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Eli Zaretskii, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Alp Aker, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Alp Aker, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Ami Fischman, 2012/10/29
- bug#12745: crash in bidi_pop_it during (idle) redisplay, Eli Zaretskii, 2012/10/29