Re: [BUG] Emacs thinks it has a BDF font

[David Abrahams]

Jason Rumney <address@hidden> writes:

> David Abrahams <address@hidden> writes:
>
>> In http://article.gmane.org/gmane.emacs.devel/16583/ I reported that
>> emacs is following an execution path which attempts to draw a BDF font
>> even though none is in use, resulting in a crash deep in the drawing
>> machinery about once a day for me.  I'm unfamiliar with this part of
>> Emacs' display code.  Is there someone who can give me a little
>> guidance about what to assert, where to set a breakpoint, or something
>> (anything) that will help us to track this down?
>
> In a previous report, you mentioned that this occured when you were
> using Gnus 5.10. Does that try to use a BDF font behind your back?

I don't think so.  I have two emacs' running at all times, only one of
which runs GNUs, and the other one is just as likely to crash
(perhaps more likely).

> If not, then you are probably looking at stack or heap
> corruption. Since it is happening in display code variables that are
> exected to change frequently, it will be very difficult to track
> down with data breakpoints. 

Or at all.

> Take a look at the structures involved,

I have, briefly.  It's hard to make much of them; they are so complex.
Is there a guide to the display structures somewhere?

> and see if there are any arrays that might overrun. assert that the
> length is within limits wherever they are written. See if you can work
> out what variables are next to the font structure on the heap or stack
> when the bug occurs. Add assertions to any arrays writes there too.

<shiver>

I guess this is going to be a tough one...

Thanks for the tips,
Dave

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com