Closed Bug 1687691 Opened 3 years ago Closed 3 years ago

RFP + gfx.bundled-fonts.activate

Categories

(Core :: Layout: Text and Fonts, enhancement)

Firefox 86
enhancement

Tracking

()

RESOLVED WORKSFORME

People

(Reporter: simon.mainey, Unassigned)

Details

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

background

  • Bug 1686274 introduced gfx.bundled-fonts.activate in FF86+
  • When RFP is enabled, font visibility is read as value 1, and bundled fonts are/were meant to be auto-included
  • Tor Browser does not use font visibility; instead they bundle some extra fonts and use the font whitelist pref. Tor Browser will set gfx.bundled-fonts.activate = 1

values

   0  disable use of app-bundled fonts
 > 0  enable use of app-bundled fonts
 < 0  default (auto): decide at startup, based on the system environment

Actual results:

the problem

On Firefox, for RFP users, we should reconcile this behavior

  • the only bundled font in Firefox windows builds is Twemoji
  • with the default setting at -1, Win8/Win10 users (without Twemoji) are easily and reliably distinguishable from Win7 users (with Twemoji)

Expected results:

possible solutions

  • when RFP = true, always ensure bundled fonts are included
  • since this is done at startup, make sure this is handled when RFP is flipped on/off (e.g. via the Privacy API)

considerations

  • we can always detect the OS as windows
  • it's much harder, but likely possible, to detect Windows versions via some other equivalency - but the Twemoji test in FF86+ would be a fingerprinter's dream come true
Component: Untriaged → Layout: Text and Fonts
Product: Firefox → Core
Version: 78 Branch → Firefox 86

Note: Bug 1670199: the font fingerprints between Win7 and Win10 [see 1] with RFP are already very divergent, so this could/should probably be a wontfix

[1] Win7 (returns 65 to 68 fonts) vs Win10 (returns 101 to 102 fonts)

Severity: -- → S3
Status: UNCONFIRMED → NEW
Ever confirmed: true

feel free to close as WORKSFORME or INVALID due to Bug 1695528

Status: NEW → RESOLVED
Closed: 3 years ago
Resolution: --- → WORKSFORME
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