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Proposal: document `browser.storage.managed` initialization semantics and provide initialization event

twschiller opened this issue · comments

commented

Summary

Problem:

  • browser.storage.managed provides policies to extensions via Google Workspace Policy/Windows GPO/ADMX/etc.
  • It appears that browser.storage.managed is not guaranteed to be set for extension installation/startup (e.g., on force install in a VDI environment)
  • There's no way to distinguish an empty browser.storage.managed policy vs. a policy that has not been initialized yet. Both seem to return {}. Update: Firefox appears to return undefined if not set
  • It doesn't appear that browser.storage.onChange is fired on initialization
  • Currently, extensions resort to hacks to try to handle the race condition: 1) waiting/retrying for 2-4 seconds, 2) automatically reloading the extension on installation
  • Policies often are used to control extension startup behavior (e.g., login screens / first run screens), so there needs to be formally defined installation/startup semantics

Proposal:

  • Document the browser.storage.managed initialization semantics/guarantees across browser vendors
    • If storage.managed should always be available at extension startup, fix the bug in Chromium
  • Document the browser.storage.onChanged behavior for initialization across browser vendors
  • If storage.managed might not be initialized on startup, provide an initialization getter and event for listening for initialization

Proposed API

browser.storage.managed {
  isInitialized: () => Promise<boolean>;
  onInitialized: Events.Event<({items: Record<string, unknown>}) => void>;
}

It would be convenient if onInitialized provided the initial values, but is unnecessary because the handler can retrieve the values in its handler (and I don't anticipate any relevant race conditions).

isInitialized is not strictly necessary if onInitialized event is guaranteed to fire at a time where the background worker has an opportunity to be listening

Current Workarounds/Hacks

Here are the current hacks that open-source browser extension use:

Vendor Behavior Inconsistency

  • "Firefox, unlike Chrome, promptly returns undefined when managed storage is not set" #547 (comment)

Related Information

commented

I've since updated Privacy Badger's workaround a bit: EFForg/privacybadger@2ac8b01?w=1

Firefox, unlike Chrome, promptly returns undefined when managed storage is not set, so there is no need for a workaround in Firefox.

As for where the Chromium managed storage race condition bug comes from: I did a bisect a while ago that led me to https://chromium.googlesource.com/chromium/src/+/1b2aef7ac8b8b5422c5ea7f02352059ab28e05ee%5E%21/

commented

@ghostwords would you be able to publish that logic as a standalone module? The issue is a few years old and it would be nice to have a centralized solution for others to use/improve.