tor-browser

InstallerPrefs.sys.mjs (4978B)

---

/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/**
* The installer prefs component provides a way to get a specific set of prefs
* from a profile into a place where the installer can read them. The primary
* reason for wanting to do this is so we can run things like Shield studies
* on installer features; normally those are enabled by setting a pref, but
* the installer runs outside of any profile and so has no access to prefs.
* So we need to do something else to allow it to read these prefs.
*
* The mechanism we use here is to reflect the values of a list of relevant
* prefs into registry values. One registry value is created for each pref
* that is set. Each installation of the product gets its own registry key
* (based on the path hash). This is obviously a somewhat wider scope than a
* single profile, but it should be close enough in enough cases to suit our
* purposes here.
*
* Currently this module only supports bool prefs. Other types could likely
* be added if needed, but it doesn't seem necessary for the primary use case.
*/

// All prefs processed through this component must be in this branch.
const INSTALLER_PREFS_BRANCH = "installer.";

// This is the list of prefs that will be reflected to the registry. It should
// be kept up to date so that it reflects the list of prefs that are in
// current use (e.g., currently active experiments).
// Only add prefs to this list which are in INSTALLER_PREFS_BRANCH;
// any others will be ignored.
const INSTALLER_PREFS_LIST = ["installer.taskbarpin.win10.enabled"];

import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";

// This constructor can take a list of prefs to override the default one,
// but this is really only intended for tests to use. Normal usage should be
// to leave the parameter omitted/undefined.
export function InstallerPrefs(prefsList) {
 this.prefsList = prefsList || INSTALLER_PREFS_LIST;

 // Each pref to be reflected will get a value created under this key, in HKCU.
 // The path will look something like:
 // "Software\Mozilla\Firefox\Installer\71AE18FE3142402B\".
 ChromeUtils.defineLazyGetter(this, "_registryKeyPath", function () {
   const app = AppConstants.MOZ_APP_NAME;
   const vendor = Services.appinfo.vendor || "Mozilla";
   const xreDirProvider = Cc[
     "@mozilla.org/xre/directory-provider;1"
   ].getService(Ci.nsIXREDirProvider);
   const installHash = xreDirProvider.getInstallHash();
   return `Software\\${vendor}\\${app}\\Installer\\${installHash}`;
 });
}

InstallerPrefs.prototype = {
 classID: Components.ID("{cd8a6995-1f19-4cdd-9ed1-d6263302f594}"),
 contractID: "@mozilla.org/installerprefs;1",

 QueryInterface: ChromeUtils.generateQI(["nsIObserver"]),

 observe(subject, topic, data) {
   switch (topic) {
     case "profile-after-change": {
       if (
         AppConstants.platform != "win" ||
         !this.prefsList ||
         !this.prefsList.length
       ) {
         // This module has no work to do.
         break;
       }
       const regKey = this._openRegKey();
       this._reflectPrefsToRegistry(regKey);
       this._registerPrefListeners();
       regKey.close();
       break;
     }
     case "nsPref:changed": {
       const regKey = this._openRegKey();
       if (this.prefsList.includes(data)) {
         this._reflectOnePrefToRegistry(regKey, data);
       }
       regKey.close();
       break;
     }
   }
 },

 _registerPrefListeners() {
   Services.prefs.addObserver(INSTALLER_PREFS_BRANCH, this);
 },

 _cleanRegistryKey(regKey) {
   for (let i = regKey.valueCount - 1; i >= 0; --i) {
     const name = regKey.getValueName(i);
     if (name.startsWith(INSTALLER_PREFS_BRANCH)) {
       regKey.removeValue(name);
     }
   }
 },

 _reflectPrefsToRegistry(regKey) {
   this._cleanRegistryKey(regKey);
   this.prefsList.forEach(pref =>
     this._reflectOnePrefToRegistry(regKey, pref)
   );
 },

 _reflectOnePrefToRegistry(regKey, pref) {
   if (!pref.startsWith(INSTALLER_PREFS_BRANCH)) {
     return;
   }

   const value = Services.prefs.getBoolPref(pref, false);
   if (value) {
     regKey.writeIntValue(pref, 1);
   } else {
     try {
       regKey.removeValue(pref);
     } catch (ex) {
       // This removeValue call is prone to failing because the value we
       // tried to remove didn't exist. Obviously that isn't really an error
       // that we need to handle.
     }
   }
 },

 _openRegKey() {
   const key = Cc["@mozilla.org/windows-registry-key;1"].createInstance(
     Ci.nsIWindowsRegKey
   );
   key.create(
     key.ROOT_KEY_CURRENT_USER,
     this._registryKeyPath,
     key.ACCESS_READ | key.ACCESS_WRITE | key.WOW64_64
   );
   return key;
 },
};