michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: "use strict";
michael@0: 
michael@0: /**
michael@0:  * Session Storage and Restoration
michael@0:  *
michael@0:  * Overview
michael@0:  * This service reads user's session file at startup, and makes a determination
michael@0:  * as to whether the session should be restored. It will restore the session
michael@0:  * under the circumstances described below.  If the auto-start Private Browsing
michael@0:  * mode is active, however, the session is never restored.
michael@0:  *
michael@0:  * Crash Detection
michael@0:  * The CrashMonitor is used to check if the final session state was successfully
michael@0:  * written at shutdown of the last session. If we did not reach
michael@0:  * 'sessionstore-final-state-write-complete', then it's assumed that the browser
michael@0:  * has previously crashed and we should restore the session.
michael@0:  *
michael@0:  * Forced Restarts
michael@0:  * In the event that a restart is required due to application update or extension
michael@0:  * installation, set the browser.sessionstore.resume_session_once pref to true,
michael@0:  * and the session will be restored the next time the browser starts.
michael@0:  *
michael@0:  * Always Resume
michael@0:  * This service will always resume the session if the integer pref
michael@0:  * browser.startup.page is set to 3.
michael@0:  */
michael@0: 
michael@0: /* :::::::: Constants and Helpers ::::::::::::::: */
michael@0: 
michael@0: const Cc = Components.classes;
michael@0: const Ci = Components.interfaces;
michael@0: const Cr = Components.results;
michael@0: const Cu = Components.utils;
michael@0: Cu.import("resource://gre/modules/XPCOMUtils.jsm");
michael@0: Cu.import("resource://gre/modules/Services.jsm");
michael@0: Cu.import("resource://gre/modules/TelemetryStopwatch.jsm");
michael@0: Cu.import("resource://gre/modules/PrivateBrowsingUtils.jsm");
michael@0: Cu.import("resource://gre/modules/Promise.jsm");
michael@0: 
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "console",
michael@0:   "resource://gre/modules/devtools/Console.jsm");
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "SessionFile",
michael@0:   "resource:///modules/sessionstore/SessionFile.jsm");
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "CrashMonitor",
michael@0:   "resource://gre/modules/CrashMonitor.jsm");
michael@0: 
michael@0: const STATE_RUNNING_STR = "running";
michael@0: 
michael@0: // 'browser.startup.page' preference value to resume the previous session.
michael@0: const BROWSER_STARTUP_RESUME_SESSION = 3;
michael@0: 
michael@0: function debug(aMsg) {
michael@0:   aMsg = ("SessionStartup: " + aMsg).replace(/\S{80}/g, "$&\n");
michael@0:   Services.console.logStringMessage(aMsg);
michael@0: }
michael@0: 
michael@0: let gOnceInitializedDeferred = Promise.defer();
michael@0: 
michael@0: /* :::::::: The Service ::::::::::::::: */
michael@0: 
michael@0: function SessionStartup() {
michael@0: }
michael@0: 
michael@0: SessionStartup.prototype = {
michael@0: 
michael@0:   // the state to restore at startup
michael@0:   _initialState: null,
michael@0:   _sessionType: Ci.nsISessionStartup.NO_SESSION,
michael@0:   _initialized: false,
michael@0: 
michael@0:   // Stores whether the previous session crashed.
michael@0:   _previousSessionCrashed: null,
michael@0: 
michael@0: /* ........ Global Event Handlers .............. */
michael@0: 
michael@0:   /**
michael@0:    * Initialize the component
michael@0:    */
michael@0:   init: function sss_init() {
michael@0:     Services.obs.notifyObservers(null, "sessionstore-init-started", null);
michael@0: 
michael@0:     // do not need to initialize anything in auto-started private browsing sessions
michael@0:     if (PrivateBrowsingUtils.permanentPrivateBrowsing) {
michael@0:       this._initialized = true;
michael@0:       gOnceInitializedDeferred.resolve();
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     SessionFile.read().then(
michael@0:       this._onSessionFileRead.bind(this),
michael@0:       console.error
michael@0:     );
michael@0:   },
michael@0: 
michael@0:   // Wrap a string as a nsISupports
michael@0:   _createSupportsString: function ssfi_createSupportsString(aData) {
michael@0:     let string = Cc["@mozilla.org/supports-string;1"]
michael@0:                    .createInstance(Ci.nsISupportsString);
michael@0:     string.data = aData;
michael@0:     return string;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Complete initialization once the Session File has been read
michael@0:    *
michael@0:    * @param stateString
michael@0:    *        string The Session State string read from disk
michael@0:    */
michael@0:   _onSessionFileRead: function (stateString) {
michael@0:     this._initialized = true;
michael@0: 
michael@0:     // Let observers modify the state before it is used
michael@0:     let supportsStateString = this._createSupportsString(stateString);
michael@0:     Services.obs.notifyObservers(supportsStateString, "sessionstore-state-read", "");
michael@0:     stateString = supportsStateString.data;
michael@0: 
michael@0:     // No valid session found.
michael@0:     if (!stateString) {
michael@0:       this._sessionType = Ci.nsISessionStartup.NO_SESSION;
michael@0:       Services.obs.notifyObservers(null, "sessionstore-state-finalized", "");
michael@0:       gOnceInitializedDeferred.resolve();
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     this._initialState = this._parseStateString(stateString);
michael@0: 
michael@0:     let shouldResumeSessionOnce = Services.prefs.getBoolPref("browser.sessionstore.resume_session_once");
michael@0:     let shouldResumeSession = shouldResumeSessionOnce ||
michael@0:           Services.prefs.getIntPref("browser.startup.page") == BROWSER_STARTUP_RESUME_SESSION;
michael@0: 
michael@0:     // If this is a normal restore then throw away any previous session
michael@0:     if (!shouldResumeSessionOnce && this._initialState) {
michael@0:       delete this._initialState.lastSessionState;
michael@0:     }
michael@0: 
michael@0:     let resumeFromCrash = Services.prefs.getBoolPref("browser.sessionstore.resume_from_crash");
michael@0: 
michael@0:     CrashMonitor.previousCheckpoints.then(checkpoints => {
michael@0:       if (checkpoints) {
michael@0:         // If the previous session finished writing the final state, we'll
michael@0:         // assume there was no crash.
michael@0:         this._previousSessionCrashed = !checkpoints["sessionstore-final-state-write-complete"];
michael@0:       } else {
michael@0:         // If the Crash Monitor could not load a checkpoints file it will
michael@0:         // provide null. This could occur on the first run after updating to
michael@0:         // a version including the Crash Monitor, or if the checkpoints file
michael@0:         // was removed.
michael@0:         //
michael@0:         // If this is the first run after an update, sessionstore.js should
michael@0:         // still contain the session.state flag to indicate if the session
michael@0:         // crashed. If it is not present, we will assume this was not the first
michael@0:         // run after update and the checkpoints file was somehow corrupted or
michael@0:         // removed by a crash.
michael@0:         //
michael@0:         // If the session.state flag is present, we will fallback to using it
michael@0:         // for crash detection - If the last write of sessionstore.js had it
michael@0:         // set to "running", we crashed.
michael@0:         let stateFlagPresent = (this._initialState &&
michael@0:                                 this._initialState.session &&
michael@0:                                 this._initialState.session.state);
michael@0: 
michael@0: 
michael@0:         this._previousSessionCrashed = !stateFlagPresent ||
michael@0:                                        (this._initialState.session.state == STATE_RUNNING_STR);
michael@0:       }
michael@0: 
michael@0:       // Report shutdown success via telemetry. Shortcoming here are
michael@0:       // being-killed-by-OS-shutdown-logic, shutdown freezing after
michael@0:       // session restore was written, etc.
michael@0:       Services.telemetry.getHistogramById("SHUTDOWN_OK").add(!this._previousSessionCrashed);
michael@0: 
michael@0:       // set the startup type
michael@0:       if (this._previousSessionCrashed && resumeFromCrash)
michael@0:         this._sessionType = Ci.nsISessionStartup.RECOVER_SESSION;
michael@0:       else if (!this._previousSessionCrashed && shouldResumeSession)
michael@0:         this._sessionType = Ci.nsISessionStartup.RESUME_SESSION;
michael@0:       else if (this._initialState)
michael@0:         this._sessionType = Ci.nsISessionStartup.DEFER_SESSION;
michael@0:       else
michael@0:         this._initialState = null; // reset the state
michael@0: 
michael@0:       Services.obs.addObserver(this, "sessionstore-windows-restored", true);
michael@0: 
michael@0:       if (this._sessionType != Ci.nsISessionStartup.NO_SESSION)
michael@0:         Services.obs.addObserver(this, "browser:purge-session-history", true);
michael@0: 
michael@0:       // We're ready. Notify everyone else.
michael@0:       Services.obs.notifyObservers(null, "sessionstore-state-finalized", "");
michael@0:       gOnceInitializedDeferred.resolve();
michael@0:     });
michael@0:   },
michael@0: 
michael@0: 
michael@0:   /**
michael@0:    * Convert the Session State string into a state object
michael@0:    *
michael@0:    * @param stateString
michael@0:    *        string The Session State string read from disk
michael@0:    * @returns {State} a Session State object
michael@0:    */
michael@0:   _parseStateString: function (stateString) {
michael@0:     let state = null;
michael@0:     let corruptFile = false;
michael@0: 
michael@0:     try {
michael@0:       state = JSON.parse(stateString);
michael@0:     } catch (ex) {
michael@0:       debug("The session file contained un-parse-able JSON: " + ex);
michael@0:       corruptFile = true;
michael@0:     }
michael@0:     Services.telemetry.getHistogramById("FX_SESSION_RESTORE_CORRUPT_FILE").add(corruptFile);
michael@0: 
michael@0:     return state;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Handle notifications
michael@0:    */
michael@0:   observe: function sss_observe(aSubject, aTopic, aData) {
michael@0:     switch (aTopic) {
michael@0:     case "app-startup":
michael@0:       Services.obs.addObserver(this, "final-ui-startup", true);
michael@0:       Services.obs.addObserver(this, "quit-application", true);
michael@0:       break;
michael@0:     case "final-ui-startup":
michael@0:       Services.obs.removeObserver(this, "final-ui-startup");
michael@0:       Services.obs.removeObserver(this, "quit-application");
michael@0:       this.init();
michael@0:       break;
michael@0:     case "quit-application":
michael@0:       // no reason for initializing at this point (cf. bug 409115)
michael@0:       Services.obs.removeObserver(this, "final-ui-startup");
michael@0:       Services.obs.removeObserver(this, "quit-application");
michael@0:       if (this._sessionType != Ci.nsISessionStartup.NO_SESSION)
michael@0:         Services.obs.removeObserver(this, "browser:purge-session-history");
michael@0:       break;
michael@0:     case "sessionstore-windows-restored":
michael@0:       Services.obs.removeObserver(this, "sessionstore-windows-restored");
michael@0:       // free _initialState after nsSessionStore is done with it
michael@0:       this._initialState = null;
michael@0:       break;
michael@0:     case "browser:purge-session-history":
michael@0:       Services.obs.removeObserver(this, "browser:purge-session-history");
michael@0:       // reset all state on sanitization
michael@0:       this._sessionType = Ci.nsISessionStartup.NO_SESSION;
michael@0:       break;
michael@0:     }
michael@0:   },
michael@0: 
michael@0: /* ........ Public API ................*/
michael@0: 
michael@0:   get onceInitialized() {
michael@0:     return gOnceInitializedDeferred.promise;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Get the session state as a jsval
michael@0:    */
michael@0:   get state() {
michael@0:     this._ensureInitialized();
michael@0:     return this._initialState;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Determines whether there is a pending session restore. Should only be
michael@0:    * called after initialization has completed.
michael@0:    * @throws Error if initialization is not complete yet.
michael@0:    * @returns bool
michael@0:    */
michael@0:   doRestore: function sss_doRestore() {
michael@0:     this._ensureInitialized();
michael@0:     return this._willRestore();
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Determines whether automatic session restoration is enabled for this
michael@0:    * launch of the browser. This does not include crash restoration. In
michael@0:    * particular, if session restore is configured to restore only in case of
michael@0:    * crash, this method returns false.
michael@0:    * @returns bool
michael@0:    */
michael@0:   isAutomaticRestoreEnabled: function () {
michael@0:     return Services.prefs.getBoolPref("browser.sessionstore.resume_session_once") ||
michael@0:            Services.prefs.getIntPref("browser.startup.page") == BROWSER_STARTUP_RESUME_SESSION;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Determines whether there is a pending session restore.
michael@0:    * @returns bool
michael@0:    */
michael@0:   _willRestore: function () {
michael@0:     return this._sessionType == Ci.nsISessionStartup.RECOVER_SESSION ||
michael@0:            this._sessionType == Ci.nsISessionStartup.RESUME_SESSION;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Returns whether we will restore a session that ends up replacing the
michael@0:    * homepage. The browser uses this to not start loading the homepage if
michael@0:    * we're going to stop its load anyway shortly after.
michael@0:    *
michael@0:    * This is meant to be an optimization for the average case that loading the
michael@0:    * session file finishes before we may want to start loading the default
michael@0:    * homepage. Should this be called before the session file has been read it
michael@0:    * will just return false.
michael@0:    *
michael@0:    * @returns bool
michael@0:    */
michael@0:   get willOverrideHomepage() {
michael@0:     if (this._initialState && this._willRestore()) {
michael@0:       let windows = this._initialState.windows || null;
michael@0:       // If there are valid windows with not only pinned tabs, signal that we
michael@0:       // will override the default homepage by restoring a session.
michael@0:       return windows && windows.some(w => w.tabs.some(t => !t.pinned));
michael@0:     }
michael@0:     return false;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Get the type of pending session store, if any.
michael@0:    */
michael@0:   get sessionType() {
michael@0:     this._ensureInitialized();
michael@0:     return this._sessionType;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Get whether the previous session crashed.
michael@0:    */
michael@0:   get previousSessionCrashed() {
michael@0:     this._ensureInitialized();
michael@0:     return this._previousSessionCrashed;
michael@0:   },
michael@0: 
michael@0:   // Ensure that initialization is complete. If initialization is not complete
michael@0:   // yet, something is attempting to use the old synchronous initialization,
michael@0:   // throw an error.
michael@0:   _ensureInitialized: function sss__ensureInitialized() {
michael@0:     if (!this._initialized) {
michael@0:       throw new Error("Session Store is not initialized.");
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /* ........ QueryInterface .............. */
michael@0:   QueryInterface : XPCOMUtils.generateQI([Ci.nsIObserver,
michael@0:                                           Ci.nsISupportsWeakReference,
michael@0:                                           Ci.nsISessionStartup]),
michael@0:   classID:          Components.ID("{ec7a6c20-e081-11da-8ad9-0800200c9a66}")
michael@0: };
michael@0: 
michael@0: this.NSGetFactory = XPCOMUtils.generateNSGetFactory([SessionStartup]);