Re: [Devel] Re: FreeType 1.4.CVS caused libgd-perl to segfault on Alpha?

[Antoine Leca]

Anthony Fok wrote:
> 
> Re: [Debian Bug report] Bug#112667: libgd-perl: build failure on alpha
> 
> Well, I have no idea, as I am not good at debugging segmentation faults.
> :-)  Anyhow, I have grabbed the latest FreeType 1 development tarball
> and packaged it as freetype1_1.4pre.20011029-1, which is already in the
> Debian archive.  Please test it and see if the segfault is there.
> 
> I have Cc'ed this message to the FreeType development mailing list.
> Perhaps the experts here could help diagnose the problem too.  :-)

First, it really looks like a problem with Freetype to me. And since
we mainly debug with Intel which are almost immune to alignment problems...
(SIGSEGV is what the Alpha library raises on alignment fault, right?)

For information, the offending code (the raster) has not been touched
(except for cosmetic fixes like copyright years) since about January 1999.
So it looks like the problem is tied to the special conditions the test
is run (the platform and/or the font).

I have no Alpha available here, and unfortunately David is quite loaded
at the moment, so he will probably not be able to dig the problem if
it is not obvious (and at first sight it does not appear to be).

More unfortunately, the raster in Freetype2 is rather another beast, so
we cannot look in that direction either.

Do you have any hint about the specificities of the font that lead to the
fault (such as an isolate pixel or something like that) that may help
narrowing the search down? Perhaps more context of the locals in
Draw_Sweep may help, too.
Also if it would be possible to have access to the very font "Generic"?
('H' is rather plain vanilla, and does not call for complex dropouts, but
perhaps the very case is special).


Antoine