Bugzilla

(In reply to gfmshj6ww from comment #38)
> (In reply to Natalia Csoregi [:nataliaCs] from comment #37)
> > https://hg.mozilla.org/mozilla-central/rev/5dfd22e748f2
> 
> Galaxy S21 Android Firefox Nightly 128.0a1 (2024-05-23) is still showing the wrong Korean font when RFP is enabled. I thought it was patched, but it seems not...
> 
> privacy.resistFingerprinting = false
> privacy.fingerprintingProtection = true
> privacy.fingerprintingProtection.overrides = +AllTargets,-FontVisibilityRestrictGenerics
> 
> With these settings, the fonts are displayed normally. However, I want the full RFP effect.

I think the issue is the way the font protection level is set. When you enable AllTargets, the FontVisibilityBaseSystem RFPTarget becomes active too, and [here](https://searchfox.org/mozilla-central/source/layout/base/nsPresContext.cpp#768) we return the font level as BaseSystem, hence not allowing the fonts in LangPack list. If you want to use fonts in LangPack (which is only `One UI Sans KR VF` for Android), then you would have to set your overrides as +AllTargets,-FontVisibilityBaseSystem. What this would essentially do it set the level to LangPack by skipping BaseSystem check.

(In reply to gfmshj6ww from comment #38)
> (In reply to Natalia Csoregi [:nataliaCs] from comment #37)
> > https://hg.mozilla.org/mozilla-central/rev/5dfd22e748f2
> 
> Galaxy S21 Android Firefox Nightly 128.0a1 (2024-05-23) is still showing the wrong Korean font when RFP is enabled. I thought it was patched, but it seems not...
> 
> privacy.resistFingerprinting = false
> privacy.fingerprintingProtection = true
> privacy.fingerprintingProtection.overrides = +AllTargets,-FontVisibilityRestrictGenerics
> 
> With these settings, the fonts are displayed normally. However, I want the full RFP effect.

I think the issue is the way the font protection level is set. When you enable AllTargets, the FontVisibilityBaseSystem RFPTarget becomes active too, and [here](https://searchfox.org/mozilla-central/source/layout/base/nsPresContext.cpp#768) we return the font level as BaseSystem, hence not allowing the fonts in LangPack list. If you want to use fonts in LangPack (which is only `One UI Sans KR VF` for Android), then you would have to set your overrides as +AllTargets,-FontVisibilityBaseSystem. What this would essentially do is, set the level to LangPack by skipping BaseSystem check.