The Tor Browser: dom/settings/SettingsChangeNotifier.jsm@97036ab72558

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

     3  * You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 "use strict"

     7 const DEBUG = false;

     8 function debug(s) {

     9   if (DEBUG) dump("-*- SettingsChangeNotifier: " + s + "\n");

    10 }

    12 const Cu = Components.utils;

    13 const Cc = Components.classes;

    14 const Ci = Components.interfaces;

    16 this.EXPORTED_SYMBOLS = ["SettingsChangeNotifier"];

    18 Cu.import("resource://gre/modules/XPCOMUtils.jsm");

    19 Cu.import("resource://gre/modules/Services.jsm");

    21 const kXpcomShutdownObserverTopic      = "xpcom-shutdown";

    22 const kMozSettingsChangedObserverTopic = "mozsettings-changed";

    23 const kFromSettingsChangeNotifier      = "fromSettingsChangeNotifier";

    25 XPCOMUtils.defineLazyServiceGetter(this, "ppmm",

    26                                    "@mozilla.org/parentprocessmessagemanager;1",

    27                                    "nsIMessageBroadcaster");

    29 this.SettingsChangeNotifier = {

    30   init: function() {

    31     if (DEBUG) debug("init");

    32     this.children = [];

    33     this._messages = ["Settings:Changed", "Settings:RegisterForMessages", "child-process-shutdown"];

    34     this._messages.forEach((function(msgName) {

    35       ppmm.addMessageListener(msgName, this);

    36     }).bind(this));

    38     Services.obs.addObserver(this, kXpcomShutdownObserverTopic, false);

    39     Services.obs.addObserver(this, kMozSettingsChangedObserverTopic, false);

    40   },

    42   observe: function(aSubject, aTopic, aData) {

    43     if (DEBUG) debug("observe");

    44     switch (aTopic) {

    45       case kXpcomShutdownObserverTopic:

    46         this._messages.forEach((function(msgName) {

    47           ppmm.removeMessageListener(msgName, this);

    48         }).bind(this));

    49         Services.obs.removeObserver(this, kXpcomShutdownObserverTopic);

    50         Services.obs.removeObserver(this, kMozSettingsChangedObserverTopic);

    51         ppmm = null;

    52         break;

    53       case kMozSettingsChangedObserverTopic:

    54       {

    55         let setting = JSON.parse(aData);

    56         // To avoid redundantly broadcasting settings-changed events that are

    57         // just requested from content processes themselves, skip the observer

    58         // messages that are notified from the internal SettingsChangeNotifier.

    59         if (setting.message && setting.message === kFromSettingsChangeNotifier)

    60           return;

    61         this.broadcastMessage("Settings:Change:Return:OK",

    62           { key: setting.key, value: setting.value });

    63         break;

    64       }

    65       default:

    66         if (DEBUG) debug("Wrong observer topic: " + aTopic);

    67         break;

    68     }

    69   },

    71   broadcastMessage: function broadcastMessage(aMsgName, aContent) {

    72     if (DEBUG) debug("Broadast");

    73     this.children.forEach(function(msgMgr) {

    74       msgMgr.sendAsyncMessage(aMsgName, aContent);

    75     });

    76   },

    78   receiveMessage: function(aMessage) {

    79     if (DEBUG) debug("receiveMessage");

    80     let msg = aMessage.data;

    81     let mm = aMessage.target;

    82     switch (aMessage.name) {

    83       case "Settings:Changed":

    84         if (!aMessage.target.assertPermission("settings-write")) {

    85           Cu.reportError("Settings message " + msg.name +

    86                          " from a content process with no 'settings-write' privileges.");

    87           return null;

    88         }

    89         this.broadcastMessage("Settings:Change:Return:OK",

    90           { key: msg.key, value: msg.value });

    91         Services.obs.notifyObservers(this, kMozSettingsChangedObserverTopic,

    92           JSON.stringify({

    93             key: msg.key,

    94             value: msg.value,

    95             message: kFromSettingsChangeNotifier

    96           }));

    97         break;

    98       case "Settings:RegisterForMessages":

    99         if (!aMessage.target.assertPermission("settings-read")) {

   100           Cu.reportError("Settings message " + msg.name +

   101                          " from a content process with no 'settings-read' privileges.");

   102           return null;

   103         }

   104         if (DEBUG) debug("Register!");

   105         if (this.children.indexOf(mm) == -1) {

   106           this.children.push(mm);

   107         }

   108         break;

   109       case "child-process-shutdown":

   110         if (DEBUG) debug("Unregister");

   111         let index;

   112         if ((index = this.children.indexOf(mm)) != -1) {

   113           if (DEBUG) debug("Unregister index: " + index);

   114           this.children.splice(index, 1);

   115         }

   116         break;

   117       default:

   118         if (DEBUG) debug("Wrong message: " + aMessage.name);

   119     }

   120   }

   121 }

   123 SettingsChangeNotifier.init();

The Tor Browser / file revision

dom/settings/SettingsChangeNotifier.jsm@97036ab72558

dom/settings/SettingsChangeNotifier.jsm