Bug 1612979 - Add functionality to UpdateUtils for automatic app update to be locked by policy r=mhowell,mkaply

Differential Revision: https://phabricator.services.mozilla.com/D63980

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

toolkit/modules/UpdateUtils.jsm

@@ -163,12 +163,22 @@ var UpdateUtils = {
    * has selected "Automatically install updates" in about:preferences.
    *
    * On Windows, this setting is shared across all profiles for the installation
-   * and is read asynchrnously from the file. On other operating systems, this
+   * and is read asynchronously from the file. On other operating systems, this
    * setting is stored in a pref and is thus a per-profile setting.
    *
    * @return A Promise that resolves with a boolean.
    */
   getAppUpdateAutoEnabled() {
+    if (Services.policies) {
+      if (!Services.policies.isAllowed("app-auto-updates-off")) {
+        // We aren't allowed to turn off auto-update - it is forced on.
+        return Promise.resolve(true);
+      }
+      if (!Services.policies.isAllowed("app-auto-updates-on")) {
+        // We aren't allowed to turn on auto-update - it is forced off.
+        return Promise.resolve(false);
+      }
+    }
     if (AppConstants.platform != "win") {
       // On platforms other than Windows the setting is stored in a preference.
       let prefValue = Services.prefs.getBoolPref(
@@ -242,9 +252,13 @@ var UpdateUtils = {
    * in about:preferences.
    *
    * On Windows, this setting is shared across all profiles for the installation
-   * and is written asynchrnously to the file. On other operating systems, this
+   * and is written asynchronously to the file. On other operating systems, this
    * setting is stored in a pref and is thus a per-profile setting.
    *
+   * If this method is called when the setting is locked, the returned promise
+   * will reject. The lock status can be determined with
+   * UpdateUtils.appUpdateAutoSettingIsLocked()
+   *
    * @param  enabled If set to true, automatic download and installation of
    *                 updates will be enabled. If set to false, this will be
    *                 disabled.
@@ -257,6 +271,12 @@ var UpdateUtils = {
    *         this operation simply sets a pref.
    */
   setAppUpdateAutoEnabled(enabledValue) {
+    if (this.appUpdateAutoSettingIsLocked()) {
+      return Promise.reject(
+        "setAppUpdateAutoEnabled: Unable to change value of setting because " +
+          "it is locked by policy"
+      );
+    }
     if (AppConstants.platform != "win") {
       // Only in Windows do we store the update config in the update directory
       let prefValue = !!enabledValue;
@@ -293,6 +313,21 @@ var UpdateUtils = {
     updateAutoIOPromise = writePromise;
     return writePromise;
   },
+
+  /**
+   * This function should be used to determine if the automatic application
+   * update setting is locked by an enterprise policy
+   *
+   * @return true if the automatic update setting is currently locked.
+   *         Otherwise, false.
+   */
+  appUpdateAutoSettingIsLocked() {
+    return (
+      Services.policies &&
+      (!Services.policies.isAllowed("app-auto-updates-off") ||
+        !Services.policies.isAllowed("app-auto-updates-on"))
+    );
+  },
 };
 
 // Used for serializing reads and writes of the app update json config file so