[HarfBuzz] bug in hb_ot_layout_lookup_collect_glyphs?

[Behdad Esfahbod]

On 14-03-16 11:08 PM, Werner LEMBERG wrote:
> 
> Behdad,
> 
> HarfBuzz doesn't validate glyph indices returned by
> `hb_ot_layout_lookup_collect_glyphs'.  I think this qualifies as a
> bug.

Hi Werner,

Not really...  It's perfectly legitimate to use non-existing glyph indices as
interim number during GSUB...  When in doubt, do your own check.

In this case, it's probably a font bug.  But I don't think we want to do
anything about that.

Cheers,
behdad

> The attached font incorrectly uses glyph index 0xFFFF in a GSUB
> lookup.  ttx says
> 
>   <GSUB>
>     ...
>     <LookupList>
>       <!-- LookupCount=8 -->   
>       <Lookup index="0">
>         <LookupType value="1"/>
>         <LookupFlag value="0"/>   
>         <!-- SubTableCount=1 -->
>         <SingleSubst index="0" Format="2">
>           ...
>           <Substitution in="uni0162" out="glyph65535"/>  
>           <Substitution in="uni0163" out="glyph65535"/>  
> 
> and HarfBuzz happily returns 0xFFFF, too.
> 
> 
>     Werner
> 
> 
> 
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-- 
behdad
http://behdad.org/