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Re: Problem report #16
From: |
Stuart D. Herring |
Subject: |
Re: Problem report #16 |
Date: |
Wed, 12 Apr 2006 11:23:36 -0700 (PDT) |
User-agent: |
SquirrelMail/1.4.3a-11.EL3 |
There's actually several possible problems here.
> > At conditional (1): "face != 0" taking false path
> >
> > 667 if (face)
> > 668 id = face->fontset;
This is a red herring -- face is reassigned later.
> > At conditional (2): "id < 0" taking true path
> >
> > 669 if (id < 0)
> > 670 fontset = Qnil;
> > 671 else
> > 672 fontset = FONTSET_FROM_ID (id);
Here's one thing I don't like: FONTSET_FROM_ID doesn't do any safety
checks on id. Can we trust this function to always get reasonable id
values?
> > 682 int face_id = XINT (elt);
> > 684 xassert (face_id == face->id);
Dan wrote (although not here in his message):
> This problem could happen if fs_load_font was called with face=NULL
> and id>0. Can that happen?
Here's where Dan's point is relevant: if face==NULL and id>0, then it
seems quite possible for this line to be reached...
> > 685 face = FACE_FROM_ID (f, face_id);
...just before assigning face, so it'd still be NULL. But there's more:
FACE_FROM_ID can fail and return NULL:
> > Event var_deref_op: Variable "face" tracked as NULL was dereferenced.
> > Also see events: [var_compare_op]
> >
> > 686 return (*get_font_info_func) (f, face->font_info_id);
So this part is dangerous if and only if face_id, derived from the
fontset, can be messed up. Nothing to do with face's value at entry to
the function. Someone who understands fontsets/font loading, comment?
Davis
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