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+/* 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/. */
+
+/**
+ * Session Storage and Restoration
+ *
+ * Overview
+ * This service reads user's session file at startup, and makes a determination
+ * as to whether the session should be restored. It will restore the session
+ * under the circumstances described below. If the auto-start Private Browsing
+ * mode is active, however, the session is never restored.
+ *
+ * Crash Detection
+ * The session file stores a session.state property, that
+ * indicates whether the browser is currently running. When the browser shuts
+ * down, the field is changed to "stopped". At startup, this field is read, and
+ * if its value is "running", then it's assumed that the browser had previously
+ * crashed, or at the very least that something bad happened, and that we should
+ * restore the session.
+ *
+ * Forced Restarts
+ * In the event that a restart is required due to application update or extension
+ * installation, set the browser.sessionstore.resume_session_once pref to true,
+ * and the session will be restored the next time the browser starts.
+ *
+ * Always Resume
+ * This service will always resume the session if the integer pref
+ * browser.startup.page is set to 3.
+ */
+
+/* :::::::: Constants and Helpers ::::::::::::::: */
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cr = Components.results;
+const Cu = Components.utils;
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/PrivateBrowsingUtils.jsm");
+Cu.import("resource://gre/modules/Promise.jsm");
+
+XPCOMUtils.defineLazyModuleGetter(this, "_SessionFile",
+ "resource:///modules/sessionstore/_SessionFile.jsm");
+
+const STATE_RUNNING_STR = "running";
+
+function debug(aMsg) {
+ aMsg = ("SessionStartup: " + aMsg).replace(/\S{80}/g, "$&\n");
+ Services.console.logStringMessage(aMsg);
+}
+
+var gOnceInitializedDeferred = Promise.defer();
+
+/* :::::::: The Service ::::::::::::::: */
+
+function SessionStartup() {
+}
+
+SessionStartup.prototype = {
+
+ // the state to restore at startup
+ _initialState: null,
+ _sessionType: Ci.nsISessionStartup.NO_SESSION,
+ _initialized: false,
+
+/* ........ Global Event Handlers .............. */
+
+ /**
+ * Initialize the component
+ */
+ init: function() {
+ // do not need to initialize anything in auto-started private browsing sessions
+ if (PrivateBrowsingUtils.permanentPrivateBrowsing) {
+ this._initialized = true;
+ gOnceInitializedDeferred.resolve();
+ return;
+ }
+
+ if (Services.prefs.getBoolPref("browser.sessionstore.resume_session_once") ||
+ Services.prefs.getIntPref("browser.startup.page") == 3) {
+ this._ensureInitialized();
+ } else {
+ _SessionFile.read().then(
+ this._onSessionFileRead.bind(this)
+ );
+ }
+ },
+
+ // Wrap a string as a nsISupports
+ _createSupportsString: function(aData) {
+ let string = Cc["@mozilla.org/supports-string;1"]
+ .createInstance(Ci.nsISupportsString);
+ string.data = aData;
+ return string;
+ },
+
+ _onSessionFileRead: function(aStateString) {
+ if (this._initialized) {
+ // Initialization is complete, nothing else to do
+ return;
+ }
+ try {
+ this._initialized = true;
+
+ // Let observers modify the state before it is used
+ let supportsStateString = this._createSupportsString(aStateString);
+ Services.obs.notifyObservers(supportsStateString, "sessionstore-state-read", "");
+ aStateString = supportsStateString.data;
+
+ // No valid session found.
+ if (!aStateString) {
+ this._sessionType = Ci.nsISessionStartup.NO_SESSION;
+ return;
+ }
+
+ // parse the session state into a JS object
+ // remove unneeded braces (added for compatibility with Firefox 2.0 and 3.0)
+ if (aStateString.charAt(0) == '(')
+ aStateString = aStateString.slice(1, -1);
+ let corruptFile = false;
+ try {
+ this._initialState = JSON.parse(aStateString);
+ }
+ catch (ex) {
+ debug("The session file contained un-parse-able JSON: " + ex);
+ // This is not valid JSON, but this might still be valid JavaScript,
+ // as used in FF2/FF3, so we need to eval.
+ // evalInSandbox will throw if aStateString is not parse-able.
+ try {
+ var s = new Cu.Sandbox("about:blank", {sandboxName: 'nsSessionStartup'});
+ this._initialState = Cu.evalInSandbox("(" + aStateString + ")", s);
+ } catch(ex) {
+ debug("The session file contained un-eval-able JSON: " + ex);
+ corruptFile = true;
+ }
+ }
+ let doResumeSessionOnce = Services.prefs.getBoolPref("browser.sessionstore.resume_session_once");
+ let doResumeSession = doResumeSessionOnce ||
+ Services.prefs.getIntPref("browser.startup.page") == 3;
+
+ // If this is a normal restore then throw away any previous session
+ if (!doResumeSessionOnce)
+ delete this._initialState.lastSessionState;
+
+ let resumeFromCrash = Services.prefs.getBoolPref("browser.sessionstore.resume_from_crash");
+ let lastSessionCrashed =
+ this._initialState && this._initialState.session &&
+ this._initialState.session.state &&
+ this._initialState.session.state == STATE_RUNNING_STR;
+
+ // set the startup type
+ if (lastSessionCrashed && resumeFromCrash)
+ this._sessionType = Ci.nsISessionStartup.RECOVER_SESSION;
+ else if (!lastSessionCrashed && doResumeSession)
+ this._sessionType = Ci.nsISessionStartup.RESUME_SESSION;
+ else if (this._initialState)
+ this._sessionType = Ci.nsISessionStartup.DEFER_SESSION;
+ else
+ this._initialState = null; // reset the state
+
+ Services.obs.addObserver(this, "sessionstore-windows-restored", true);
+
+ if (this._sessionType != Ci.nsISessionStartup.NO_SESSION)
+ Services.obs.addObserver(this, "browser:purge-session-history", true);
+
+ } finally {
+ // We're ready. Notify everyone else.
+ Services.obs.notifyObservers(null, "sessionstore-state-finalized", "");
+ gOnceInitializedDeferred.resolve();
+ }
+ },
+
+ /**
+ * Handle notifications
+ */
+ observe: function(aSubject, aTopic, aData) {
+ switch (aTopic) {
+ case "app-startup":
+ Services.obs.addObserver(this, "final-ui-startup", true);
+ Services.obs.addObserver(this, "quit-application", true);
+ break;
+ case "final-ui-startup":
+ Services.obs.removeObserver(this, "final-ui-startup");
+ Services.obs.removeObserver(this, "quit-application");
+ this.init();
+ break;
+ case "quit-application":
+ // no reason for initializing at this point (cf. bug 409115)
+ Services.obs.removeObserver(this, "final-ui-startup");
+ Services.obs.removeObserver(this, "quit-application");
+ if (this._sessionType != Ci.nsISessionStartup.NO_SESSION)
+ Services.obs.removeObserver(this, "browser:purge-session-history");
+ break;
+ case "sessionstore-windows-restored":
+ Services.obs.removeObserver(this, "sessionstore-windows-restored");
+ // free _initialState after nsSessionStore is done with it
+ this._initialState = null;
+ break;
+ case "browser:purge-session-history":
+ Services.obs.removeObserver(this, "browser:purge-session-history");
+ // reset all state on sanitization
+ this._sessionType = Ci.nsISessionStartup.NO_SESSION;
+ break;
+ }
+ },
+
+/* ........ Public API ................*/
+
+ get onceInitialized() {
+ return gOnceInitializedDeferred.promise;
+ },
+
+ /**
+ * Get the session state as a jsval
+ */
+ get state() {
+ this._ensureInitialized();
+ return this._initialState;
+ },
+
+ /**
+ * Determines whether there is a pending session restore and makes sure that
+ * we're initialized before returning. If we're not yet this will read the
+ * session file synchronously.
+ * @returns bool
+ */
+ doRestore: function() {
+ this._ensureInitialized();
+ return this._willRestore();
+ },
+
+ /**
+ * Determines whether there is a pending session restore.
+ * @returns bool
+ */
+ _willRestore: function() {
+ return this._sessionType == Ci.nsISessionStartup.RECOVER_SESSION ||
+ this._sessionType == Ci.nsISessionStartup.RESUME_SESSION;
+ },
+
+ /**
+ * Returns whether we will restore a session that ends up replacing the
+ * homepage. The browser uses this to not start loading the homepage if
+ * we're going to stop its load anyway shortly after.
+ *
+ * This is meant to be an optimization for the average case that loading the
+ * session file finishes before we may want to start loading the default
+ * homepage. Should this be called before the session file has been read it
+ * will just return false.
+ *
+ * @returns bool
+ */
+ get willOverrideHomepage() {
+ if (this._initialState && this._willRestore()) {
+ let windows = this._initialState.windows || null;
+ // If there are valid windows with not only pinned tabs, signal that we
+ // will override the default homepage by restoring a session.
+ return windows && windows.some(w => w.tabs.some(t => !t.pinned));
+ }
+ return false;
+ },
+
+ /**
+ * Get the type of pending session store, if any.
+ */
+ get sessionType() {
+ this._ensureInitialized();
+ return this._sessionType;
+ },
+
+ // Ensure that initialization is complete.
+ // If initialization is not complete yet, fall back to a synchronous
+ // initialization and kill ongoing asynchronous initialization
+ _ensureInitialized: function() {
+ try {
+ if (this._initialized) {
+ // Initialization is complete, nothing else to do
+ return;
+ }
+ let contents = _SessionFile.syncRead();
+ this._onSessionFileRead(contents);
+ } catch(ex) {
+ debug("ensureInitialized: could not read session " + ex + ", " + ex.stack);
+ throw ex;
+ }
+ },
+
+ /* ........ QueryInterface .............. */
+ QueryInterface : XPCOMUtils.generateQI([Ci.nsIObserver,
+ Ci.nsISupportsWeakReference,
+ Ci.nsISessionStartup]),
+ classID: Components.ID("{ec7a6c20-e081-11da-8ad9-0800200c9a66}")
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([SessionStartup]);