Mypal68/toolkit/components/contentprefs/ContentPrefServiceParent.jsm

/* 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/. */

"use strict";

var EXPORTED_SYMBOLS = ["ContentPrefServiceParent"];

const { XPCOMUtils } = ChromeUtils.import(
  "resource://gre/modules/XPCOMUtils.jsm"
);

ChromeUtils.defineModuleGetter(
  this,
  "_methodsCallableFromChild",
  "resource://gre/modules/ContentPrefUtils.jsm"
);

let loadContext = Cu.createLoadContext();
let privateLoadContext = Cu.createPrivateLoadContext();

function contextArg(context) {
  return context && context.usePrivateBrowsing
    ? privateLoadContext
    : loadContext;
}

var ContentPrefServiceParent = {
  // Called on all platforms.
  alwaysInit() {
    let globalMM = Cc[
      "@mozilla.org/parentprocessmessagemanager;1"
    ].getService();

    globalMM.addMessageListener("child-process-shutdown", this);
  },

  // Only called on Android. Listeners are added in BrowserGlue.jsm on other
  // platforms.
  init() {
    let globalMM = Cc[
      "@mozilla.org/parentprocessmessagemanager;1"
    ].getService();

    // PLEASE KEEP THIS LIST IN SYNC WITH THE LISTENERS ADDED IN nsBrowserGlue
    globalMM.addMessageListener("ContentPrefs:FunctionCall", this);
    globalMM.addMessageListener("ContentPrefs:AddObserverForName", this);
    globalMM.addMessageListener("ContentPrefs:RemoveObserverForName", this);
    // PLEASE KEEP THIS LIST IN SYNC WITH THE LISTENERS ADDED IN nsBrowserGlue

    this.alwaysInit();
  },

  // Map from message manager -> content pref observer.
  _observers: new Map(),

  handleObserverChange(msg) {
    let observer = this._observers.get(msg.target);
    if (msg.name === "child-process-shutdown") {
      // If we didn't have any observers for this child process, don't do
      // anything.
      if (!observer) {
        return;
      }

      for (let i of observer._names) {
        this._cps2.removeObserverForName(i, observer);
      }

      this._observers.delete(msg.target);
      return;
    }

    let prefName = msg.data.name;
    if (msg.name === "ContentPrefs:AddObserverForName") {
      // The child process is responsible for not adding multiple parent
      // observers for the same name.
      if (!observer) {
        observer = {
          onContentPrefSet(group, name, value, isPrivate) {
            msg.target.sendAsyncMessage("ContentPrefs:NotifyObservers", {
              name,
              callback: "onContentPrefSet",
              args: [group, name, value, isPrivate],
            });
          },

          onContentPrefRemoved(group, name, isPrivate) {
            msg.target.sendAsyncMessage("ContentPrefs:NotifyObservers", {
              name,
              callback: "onContentPrefRemoved",
              args: [group, name, isPrivate],
            });
          },

          // The names we're using this observer object for, used to keep track
          // of the number of names we care about as well as for removing this
          // observer if its associated process goes away.
          _names: new Set(),
        };

        this._observers.set(msg.target, observer);
      }

      observer._names.add(prefName);

      this._cps2.addObserverForName(prefName, observer);
    } else {
      // RemoveObserverForName

      // We must have an observer.
      this._cps2.removeObserverForName(prefName, observer);

      observer._names.delete(prefName);
      if (observer._names.size === 0) {
        // This was the last use for this observer.
        this._observers.delete(msg.target);
      }
    }
  },

  // Listeners are added in BrowserGlue.jsm
  receiveMessage(msg) {
    if (msg.name != "ContentPrefs:FunctionCall") {
      this.handleObserverChange(msg);
      return;
    }

    let data = msg.data;
    let signature;

    if (
      !_methodsCallableFromChild.some(([method, args]) => {
        if (method == data.call) {
          signature = args;
          return true;
        }
        return false;
      })
    ) {
      throw new Error(`Can't call ${data.call} from child!`);
    }

    let args = data.args;
    let requestId = data.requestId;

    let listener = {
      handleResult(pref) {
        msg.target.sendAsyncMessage("ContentPrefs:HandleResult", {
          requestId,
          contentPref: {
            domain: pref.domain,
            name: pref.name,
            value: pref.value,
          },
        });
      },

      handleError(error) {
        msg.target.sendAsyncMessage("ContentPrefs:HandleError", {
          requestId,
          error,
        });
      },
      handleCompletion(reason) {
        msg.target.sendAsyncMessage("ContentPrefs:HandleCompletion", {
          requestId,
          reason,
        });
      },
    };

    // Push our special listener.
    args.push(listener);

    // Process context argument for forwarding
    let contextIndex = signature.indexOf("context");
    if (contextIndex > -1) {
      args[contextIndex] = contextArg(args[contextIndex]);
    }

    // And call the function.
    this._cps2[data.call](...args);
  },
};

XPCOMUtils.defineLazyServiceGetter(
  ContentPrefServiceParent,
  "_cps2",
  "@mozilla.org/content-pref/service;1",
  "nsIContentPrefService2"
);