[HarfBuzz] Valid range of deltaGlyphID is too small

[Behdad Esfahbod]

On 09/27/11 06:27, Jonathan Kew wrote:

> 
> Behdad can no doubt identify the proper place to fix this, either immediately in SingleSubstFormat1::apply where the deltaGlyphID addition is done, or somewhere more general under replace_glyph(). (Not sure offhand if there may be other potential sources of glyph-ID-arithmetic overflow?)

I confirmed that Adobe believes SingleSubstFormat1 always has to return a
16-bit value and pushed a fix.  Note that this essentially makes the sign of
the delta irrelevant.

I believe that's the only case needing this fix.

behdad

> JK