1560437 - If font.system.whitelist does not include any available fonts, disable whitelisting (as if the list were empty)

Status: RESOLVED FIXED

(Core :: Graphics: Text, enhancement, P3)

Description

[Jonathan Kew [:jfkthame]]

If the font.system.whitelist pref (from bug 1121643) is empty, no whitelist is applied and all installed fonts are available to the browser.

If it lists one or more of the system's installed font families, only these are available to use.

However, if the pref is non-empty, but does not list any font families that are actually installed, what should happen? Currently, when the list of installed fonts is being filtered by the whitelist, we just ensure that the last entry is not deleted, so one font will remain available. Which font this will be is rather arbitrary, depending on the order of iteration over the font-families hashtable.

I don't think this is particularly good behavior: it's arbitrary and unpredictable, and it can result in the only available font being something like a symbol or dingbat font that is not really useful at all - at which point the Firefox UI becomes pretty unusable, with things like about:config becoming unreadable.

A more sensible option, I think, would be to treat a whitelist containing no available fonts the same as an empty whitelist, and just not filter the list at all. This avoids the arbitrariness of just picking the "last font standing", and potentially leaving the user with a broken UI.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1560437 - Ignore font.system.whitelist if no whitelisted fonts are found. r=jrmuizel

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug is a enhancement, but please change it back in case of error.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/61656a6d3217
Ignore font.system.whitelist if no whitelisted fonts are found. r=jrmuizel

Comment 4

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/61656a6d3217