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

[Jason Rumney <jasonr@gnu.org>]

David Abrahams <dave@boost-consulting.com> 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?

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. Take a look at the structures involved,
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.