Bug 1567247 Part 1 - Reflect a fixed list of prefs into the Windows registry...

Bug 1567247 Part 1 - Reflect a fixed list of prefs into the Windows registry so the installer can read them. r=agashlin

Differential Revision: https://phabricator.services.mozilla.com/D40326

--HG--
extra : moz-landing-system : lando

browser/components/installerprefs/InstallerPrefs.jsm

+/* -*- 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 = [];
+
+const { AppConstants } = ChromeUtils.import(
+  "resource://gre/modules/AppConstants.jsm"
+);
+const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
+const { XPCOMUtils } = ChromeUtils.import(
+  "resource://gre/modules/XPCOMUtils.jsm"
+);
+
+// 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.
+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\".
+  XPCOMUtils.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([Ci.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) {
+      regKey.removeValue(regKey.getValueName(i));
+    }
+  },
+
+  _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;
+  },
+};
+
+var EXPORTED_SYMBOLS = ["InstallerPrefs"];

browser/components/installerprefs/components.conf

+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+Classes = [
+    {
+        'cid': '{cd8a6995-1f19-4cdd-9ed1-d6263302f594}',
+        'contract_ids': ['@mozilla.org/installerprefs;1'],
+        'jsm': 'resource:///modules/InstallerPrefs.jsm',
+        'constructor': 'InstallerPrefs',
+        'categories': {'profile-after-change': 'InstallerPrefs'},
+        'processes': ProcessSelector.MAIN_PROCESS_ONLY,
+    },
+]

browser/components/installerprefs/moz.build

+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+with Files('**'):
+    BUG_COMPONENT = ('Firefox', 'Installer')
+
+EXTRA_JS_MODULES += [
+    'InstallerPrefs.jsm',
+]
+
+XPCOM_MANIFESTS += [
+    'components.conf',
+]

browser/components/moz.build

@@ -66,6 +66,8 @@ if CONFIG['NIGHTLY_BUILD']:
 
 if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
     DIRS += ['touchbar']
+elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':
+    DIRS += ['installerprefs']
 
 XPIDL_SOURCES += [
     'nsIBrowserHandler.idl',