bug#6621: Emacs crash when trying to report emacs crash

[Kenichi Handa <handa@m17n.org>]

In article <AANLkTikE5X6BUROA31sXDe7FyIXqy_ZRm-J7iiZb_l4I@mail.gmail.com>, Yair F <yair.f.lists@gmail.com> writes:

> Since Handa-san is appearnly unavailable I tried to investigate the
> crash myself.
> The problem that I know nothing about emacs' structure.
> All I can do is send the debug session. If you  think that you can
> instruct me more on how to debug it let me know.
> I'll try to get something more meaningful.

Thank you, and sorry for the late response.  I've been busy
for preparing for the next Monday's presentation.

I found a suspicious code in Ffont_shape_gstring, and the
attached patch will fix the bug.  Could you please try it?
I have not yet committed it because I have not yet fully
traced the impact of the change to the other places..

=== modified file 'src/font.c'
--- src/font.c	2010-07-14 03:40:47 +0000
+++ src/font.c	2010-07-23 12:31:43 +0000
@@ -4492,6 +4492,8 @@
     }
   if (i == 3 || XINT (n) == 0)
     return Qnil;
+  if (XINT (n) < LGSTRING_GLYPH_LEN (gstring))
+    LGSTRING_SET_GLYPH (gstring, XINT (n), Qnil);
 
   glyph = LGSTRING_GLYPH (gstring, 0);
   from = LGLYPH_FROM (glyph);

---
Kenichi Handa
handa@m17n.org