gecko-dev/browser/modules/Sanitizer.jsm

// -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
/* 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/. */

var EXPORTED_SYMBOLS = ["Sanitizer"];

ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
ChromeUtils.import("resource://gre/modules/Services.jsm");

XPCOMUtils.defineLazyModuleGetters(this, {
  AppConstants: "resource://gre/modules/AppConstants.jsm",
  PlacesUtils: "resource://gre/modules/PlacesUtils.jsm",
  FormHistory: "resource://gre/modules/FormHistory.jsm",
  TelemetryStopwatch: "resource://gre/modules/TelemetryStopwatch.jsm",
  ContextualIdentityService: "resource://gre/modules/ContextualIdentityService.jsm",
});

XPCOMUtils.defineLazyServiceGetter(this, "quotaManagerService",
                                   "@mozilla.org/dom/quota-manager-service;1",
                                   "nsIQuotaManagerService");
XPCOMUtils.defineLazyServiceGetter(this, "serviceWorkerManager",
                                   "@mozilla.org/serviceworkers/manager;1",
                                   "nsIServiceWorkerManager");


// Used as unique id for pending sanitizations.
var gPendingSanitizationSerial = 0;

/**
 * Cookie lifetime policy is currently used to cleanup on shutdown other
 * components such as QuotaManager, localStorage, ServiceWorkers.
 */
const PREF_COOKIE_LIFETIME = "network.cookie.lifetimePolicy";

var Sanitizer = {
  /**
   * Whether we should sanitize on shutdown.
   */
  PREF_SANITIZE_ON_SHUTDOWN: "privacy.sanitize.sanitizeOnShutdown",

  /**
   * During a sanitization this is set to a JSON containing an array of the
   * pending sanitizations. This allows to retry sanitizations on startup in
   * case they dind't run or were interrupted by a crash.
   * Use addPendingSanitization and removePendingSanitization to manage it.
   */
  PREF_PENDING_SANITIZATIONS: "privacy.sanitize.pending",

  /**
   * Pref branches to fetch sanitization options from.
   */
  PREF_CPD_BRANCH: "privacy.cpd.",
  PREF_SHUTDOWN_BRANCH: "privacy.clearOnShutdown.",

  /**
   * The fallback timestamp used when no argument is given to
   * Sanitizer.getClearRange.
   */
  PREF_TIMESPAN: "privacy.sanitize.timeSpan",

  /**
   * Pref to newTab segregation. If true, on shutdown, the private container
   * used in about:newtab is cleaned up.  Exposed because used in tests.
   */
  PREF_NEWTAB_SEGREGATION: "privacy.usercontext.about_newtab_segregation.enabled",

  /**
   * Time span constants corresponding to values of the privacy.sanitize.timeSpan
   * pref.  Used to determine how much history to clear, for various items
   */
  TIMESPAN_EVERYTHING: 0,
  TIMESPAN_HOUR:       1,
  TIMESPAN_2HOURS:     2,
  TIMESPAN_4HOURS:     3,
  TIMESPAN_TODAY:      4,
  TIMESPAN_5MIN:       5,
  TIMESPAN_24HOURS:    6,

  /**
   * Whether we should sanitize on shutdown.
   * When this is set, a pending sanitization should also be added and removed
   * when shutdown sanitization is complete. This allows to retry incomplete
   * sanitizations on startup.
   */
  shouldSanitizeOnShutdown: false,

  /**
   * Whether we should sanitize the private container for about:newtab.
   */
  shouldSanitizeNewTabContainer: false,

  /**
   * Shows a sanitization dialog to the user.
   *
   * @param [optional] parentWindow the window to use as
   *                   parent for the created dialog.
   */
  showUI(parentWindow) {
    let win = AppConstants.platform == "macosx" ?
      null : // make this an app-modal window on Mac
      parentWindow;
    Services.ww.openWindow(win,
                           "chrome://browser/content/sanitize.xul",
                           "Sanitize",
                           "chrome,titlebar,dialog,centerscreen,modal",
                           null);
  },

  /**
   * Performs startup tasks:
   *  - Checks if sanitizations were not completed during the last session.
   *  - Registers sanitize-on-shutdown.
   */
  async onStartup() {
    // First, collect pending sanitizations from the last session, before we
    // add pending sanitizations for this session.
    let pendingSanitizations = getAndClearPendingSanitizations();

    // Check if we should sanitize on shutdown.
    this.shouldSanitizeOnShutdown =
      Services.prefs.getBoolPref(Sanitizer.PREF_SANITIZE_ON_SHUTDOWN, false);
    Services.prefs.addObserver(Sanitizer.PREF_SANITIZE_ON_SHUTDOWN, this, true);
    // Add a pending shutdown sanitization, if necessary.
    if (this.shouldSanitizeOnShutdown) {
      let itemsToClear = getItemsToClearFromPrefBranch(Sanitizer.PREF_SHUTDOWN_BRANCH);
      addPendingSanitization("shutdown", itemsToClear, {});
    }
    // Shutdown sanitization is always pending, but the user may change the
    // sanitize on shutdown prefs during the session. Then the pending
    // sanitization would become stale and must be updated.
    Services.prefs.addObserver(Sanitizer.PREF_SHUTDOWN_BRANCH, this, true);

    // Make sure that we are triggered during shutdown.
    let shutdownClient = PlacesUtils.history.shutdownClient.jsclient;
    // We need to pass to sanitize() (through sanitizeOnShutdown) a state object
    // that tracks the status of the shutdown blocker. This `progress` object
    // will be updated during sanitization and reported with the crash in case of
    // a shutdown timeout.
    // We use the `options` argument to pass the `progress` object to sanitize().
    let progress = { isShutdown: true };
    shutdownClient.addBlocker("sanitize.js: Sanitize on shutdown",
      () => sanitizeOnShutdown(progress),
      {fetchState: () => ({ progress })}
    );

    this.shouldSanitizeNewTabContainer = Services.prefs.getBoolPref(this.PREF_NEWTAB_SEGREGATION, false);
    if (this.shouldSanitizeNewTabContainer) {
      addPendingSanitization("newtab-container", [], {});
    }

    let i = pendingSanitizations.findIndex(s => s.id == "newtab-container");
    if (i != -1) {
      pendingSanitizations.splice(i, 1);
      sanitizeNewTabSegregation();
    }

    // Finally, run the sanitizations that were left pending, because we crashed
    // before completing them.
    for (let {itemsToClear, options} of pendingSanitizations) {
      try {
        await this.sanitize(itemsToClear, options);
      } catch (ex) {
        Cu.reportError("A previously pending sanitization failed: " + itemsToClear + "\n" + ex);
      }
    }
  },

  /**
   * Returns a 2 element array representing the start and end times,
   * in the uSec-since-epoch format that PRTime likes. If we should
   * clear everything, this function returns null.
   *
   * @param ts [optional] a timespan to convert to start and end time.
   *                      Falls back to the privacy.sanitize.timeSpan preference
   *                      if this argument is omitted.
   *                      If this argument is provided, it has to be one of the
   *                      Sanitizer.TIMESPAN_* constants. This function will
   *                      throw an error otherwise.
   *
   * @return {Array} a 2-element Array containing the start and end times.
   */
  getClearRange(ts) {
    if (ts === undefined)
      ts = Services.prefs.getIntPref(Sanitizer.PREF_TIMESPAN);
    if (ts === Sanitizer.TIMESPAN_EVERYTHING)
      return null;

    // PRTime is microseconds while JS time is milliseconds
    var endDate = Date.now() * 1000;
    switch (ts) {
      case Sanitizer.TIMESPAN_5MIN :
        var startDate = endDate - 300000000; // 5*60*1000000
        break;
      case Sanitizer.TIMESPAN_HOUR :
        startDate = endDate - 3600000000; // 1*60*60*1000000
        break;
      case Sanitizer.TIMESPAN_2HOURS :
        startDate = endDate - 7200000000; // 2*60*60*1000000
        break;
      case Sanitizer.TIMESPAN_4HOURS :
        startDate = endDate - 14400000000; // 4*60*60*1000000
        break;
      case Sanitizer.TIMESPAN_TODAY :
        var d = new Date(); // Start with today
        d.setHours(0); // zero us back to midnight...
        d.setMinutes(0);
        d.setSeconds(0);
        d.setMilliseconds(0);
        startDate = d.valueOf() * 1000; // convert to epoch usec
        break;
      case Sanitizer.TIMESPAN_24HOURS :
        startDate = endDate - 86400000000; // 24*60*60*1000000
        break;
      default:
        throw "Invalid time span for clear private data: " + ts;
    }
    return [startDate, endDate];
  },

  /**
   * Deletes privacy sensitive data in a batch, according to user preferences.
   * Returns a promise which is resolved if no errors occurred.  If an error
   * occurs, a message is reported to the console and all other items are still
   * cleared before the promise is finally rejected.
   *
   * @param [optional] itemsToClear
   *        Array of items to be cleared. if specified only those
   *        items get cleared, irrespectively of the preference settings.
   * @param [optional] options
   *        Object whose properties are options for this sanitization:
   *         - ignoreTimespan (default: true): Time span only makes sense in
   *           certain cases.  Consumers who want to only clear some private
   *           data can opt in by setting this to false, and can optionally
   *           specify a specific range.
   *           If timespan is not ignored, and range is not set, sanitize() will
   *           use the value of the timespan pref to determine a range.
   *         - range (default: null)
   *         - privateStateForNewWindow (default: "non-private"): when clearing
   *           open windows, defines the private state for the newly opened window.
   */
  async sanitize(itemsToClear = null, options = {}) {
    let progress = options.progress || {};
    if (!itemsToClear)
      itemsToClear = getItemsToClearFromPrefBranch(this.PREF_CPD_BRANCH);
    let promise = sanitizeInternal(this.items, itemsToClear, progress, options);

    // Depending on preferences, the sanitizer may perform asynchronous
    // work before it starts cleaning up the Places database (e.g. closing
    // windows). We need to make sure that the connection to that database
    // hasn't been closed by the time we use it.
    // Though, if this is a sanitize on shutdown, we already have a blocker.
    if (!progress.isShutdown) {
      let shutdownClient = PlacesUtils.history.shutdownClient.jsclient;
      shutdownClient.addBlocker("sanitize.js: Sanitize",
        promise,
        {
          fetchState: () => ({ progress })
        }
      );
    }

    try {
      await promise;
    } finally {
      Services.obs.notifyObservers(null, "sanitizer-sanitization-complete");
    }
  },

  observe(subject, topic, data) {
    if (topic == "nsPref:changed") {
      if (data.startsWith(this.PREF_SHUTDOWN_BRANCH) &&
          this.shouldSanitizeOnShutdown) {
        // Update the pending shutdown sanitization.
        removePendingSanitization("shutdown");
        let itemsToClear = getItemsToClearFromPrefBranch(Sanitizer.PREF_SHUTDOWN_BRANCH);
        addPendingSanitization("shutdown", itemsToClear, {});
      } else if (data == this.PREF_SANITIZE_ON_SHUTDOWN) {
        this.shouldSanitizeOnShutdown =
          Services.prefs.getBoolPref(Sanitizer.PREF_SANITIZE_ON_SHUTDOWN, false);
        removePendingSanitization("shutdown");
        if (this.shouldSanitizeOnShutdown) {
          let itemsToClear = getItemsToClearFromPrefBranch(Sanitizer.PREF_SHUTDOWN_BRANCH);
          addPendingSanitization("shutdown", itemsToClear, {});
        }
      } else if (data == this.PREF_NEWTAB_SEGREGATION) {
        this.shouldSanitizeNewTabContainer = Services.prefs.getBoolPref(this.PREF_NEWTAB_SEGREGATION, false);
        removePendingSanitization("newtab-container");
        if (this.shouldSanitizeNewTabContainer) {
          addPendingSanitization("newtab-container", [], {});
        }
      }
    }
  },

  QueryInterface: ChromeUtils.generateQI([
    Ci.nsiObserver,
    Ci.nsISupportsWeakReference
  ]),

  // This method is meant to be used by tests.
  async runSanitizeOnShutdown() {
    return sanitizeOnShutdown({ isShutdown: true });
  },

  // When making any changes to the sanitize implementations here,
  // please check whether the changes are applicable to Android
  // (mobile/android/modules/Sanitizer.jsm) as well.

  items: {
    cache: {
      async clear(range) {
        let refObj = {};
        TelemetryStopwatch.start("FX_SANITIZE_CACHE", refObj);
        await clearData(range, Ci.nsIClearDataService.CLEAR_ALL_CACHES);
        TelemetryStopwatch.finish("FX_SANITIZE_CACHE", refObj);
      }
    },

    cookies: {
      async clear(range) {
        let refObj = {};
        TelemetryStopwatch.start("FX_SANITIZE_COOKIES_2", refObj);
        await clearData(range, Ci.nsIClearDataService.CLEAR_COOKIES |
                               Ci.nsIClearDataService.CLEAR_PLUGIN_DATA |
                               Ci.nsIClearDataService.CLEAR_MEDIA_DEVICES);
        TelemetryStopwatch.finish("FX_SANITIZE_COOKIES_2", refObj);
      },
    },

    offlineApps: {
      async clear(range) {
        await clearData(range, Ci.nsIClearDataService.CLEAR_DOM_STORAGES);
      }
    },

    history: {
      async clear(range) {
        let refObj = {};
        TelemetryStopwatch.start("FX_SANITIZE_HISTORY", refObj);
        await clearData(range, Ci.nsIClearDataService.CLEAR_HISTORY |
                               Ci.nsIClearDataService.CLEAR_SESSION_HISTORY);
        TelemetryStopwatch.finish("FX_SANITIZE_HISTORY", refObj);
      }
    },

    formdata: {
      async clear(range) {
        let seenException;
        let refObj = {};
        TelemetryStopwatch.start("FX_SANITIZE_FORMDATA", refObj);
        try {
          // Clear undo history of all search bars.
          let windows = Services.wm.getEnumerator("navigator:browser");
          while (windows.hasMoreElements()) {
            let currentWindow = windows.getNext();
            let currentDocument = currentWindow.document;

            // searchBar.textbox may not exist due to the search bar binding
            // not having been constructed yet if the search bar is in the
            // overflow or menu panel. It won't have a value or edit history in
            // that case.
            let searchBar = currentDocument.getElementById("searchbar");
            if (searchBar && searchBar.textbox)
              searchBar.textbox.reset();

            let tabBrowser = currentWindow.gBrowser;
            if (!tabBrowser) {
              // No tab browser? This means that it's too early during startup (typically,
              // Session Restore hasn't completed yet). Since we don't have find
              // bars at that stage and since Session Restore will not restore
              // find bars further down during startup, we have nothing to clear.
              continue;
            }
            for (let tab of tabBrowser.tabs) {
              if (tabBrowser.isFindBarInitialized(tab))
                tabBrowser.getCachedFindBar(tab).clear();
            }
            // Clear any saved find value
            tabBrowser._lastFindValue = "";
          }
        } catch (ex) {
          seenException = ex;
        }

        try {
          let change = { op: "remove" };
          if (range) {
            [ change.firstUsedStart, change.firstUsedEnd ] = range;
          }
          await new Promise(resolve => {
            FormHistory.update(change, {
              handleError(e) {
                seenException = new Error("Error " + e.result + ": " + e.message);
              },
              handleCompletion() {
                resolve();
              }
            });
          });
        } catch (ex) {
          seenException = ex;
        }

        TelemetryStopwatch.finish("FX_SANITIZE_FORMDATA", refObj);
        if (seenException) {
          throw seenException;
        }
      }
    },

    downloads: {
      async clear(range) {
        let refObj = {};
        TelemetryStopwatch.start("FX_SANITIZE_DOWNLOADS", refObj);
        await clearData(range, Ci.nsIClearDataService.CLEAR_DOWNLOADS);
        TelemetryStopwatch.finish("FX_SANITIZE_DOWNLOADS", refObj);
      }
    },

    sessions: {
      async clear(range) {
        let refObj = {};
        TelemetryStopwatch.start("FX_SANITIZE_SESSIONS", refObj);
        await clearData(range, Ci.nsIClearDataService.CLEAR_AUTH_TOKENS |
                               Ci.nsIClearDataService.CLEAR_AUTH_CACHE);
        TelemetryStopwatch.finish("FX_SANITIZE_SESSIONS", refObj);
      }
    },

    siteSettings: {
      async clear(range) {
        let refObj = {};
        TelemetryStopwatch.start("FX_SANITIZE_SITESETTINGS", refObj);
        await clearData(range, Ci.nsIClearDataService.CLEAR_PERMISSIONS |
                               Ci.nsIClearDataService.CLEAR_CONTENT_PREFERENCES |
                               Ci.nsIClearDataService.CLEAR_DOM_PUSH_NOTIFICATIONS |
                               Ci.nsIClearDataService.CLEAR_SECURITY_SETTINGS);
        TelemetryStopwatch.finish("FX_SANITIZE_SITESETTINGS", refObj);
      }
    },

    openWindows: {
      _canCloseWindow(win) {
        if (win.CanCloseWindow()) {
          // We already showed PermitUnload for the window, so let's
          // make sure we don't do it again when we actually close the
          // window.
          win.skipNextCanClose = true;
          return true;
        }
        return false;
      },
      _resetAllWindowClosures(windowList) {
        for (let win of windowList) {
          win.skipNextCanClose = false;
        }
      },
      async clear(range, privateStateForNewWindow = "non-private") {
        // NB: this closes all *browser* windows, not other windows like the library, about window,
        // browser console, etc.

        // Keep track of the time in case we get stuck in la-la-land because of onbeforeunload
        // dialogs
        let existingWindow = Services.appShell.hiddenDOMWindow;
        let startDate = existingWindow.performance.now();

        // First check if all these windows are OK with being closed:
        let windowEnumerator = Services.wm.getEnumerator("navigator:browser");
        let windowList = [];
        while (windowEnumerator.hasMoreElements()) {
          let someWin = windowEnumerator.getNext();
          windowList.push(someWin);
          // If someone says "no" to a beforeunload prompt, we abort here:
          if (!this._canCloseWindow(someWin)) {
            this._resetAllWindowClosures(windowList);
            throw new Error("Sanitize could not close windows: cancelled by user");
          }

          // ...however, beforeunload prompts spin the event loop, and so the code here won't get
          // hit until the prompt has been dismissed. If more than 1 minute has elapsed since we
          // started prompting, stop, because the user might not even remember initiating the
          // 'forget', and the timespans will be all wrong by now anyway:
          if (existingWindow.performance.now() > (startDate + 60 * 1000)) {
            this._resetAllWindowClosures(windowList);
            throw new Error("Sanitize could not close windows: timeout");
          }
        }

        // If/once we get here, we should actually be able to close all windows.

        let refObj = {};
        TelemetryStopwatch.start("FX_SANITIZE_OPENWINDOWS", refObj);

        // First create a new window. We do this first so that on non-mac, we don't
        // accidentally close the app by closing all the windows.
        let handler = Cc["@mozilla.org/browser/clh;1"].getService(Ci.nsIBrowserHandler);
        let defaultArgs = handler.defaultArgs;
        let features = "chrome,all,dialog=no," + privateStateForNewWindow;
        let newWindow = existingWindow.openDialog(AppConstants.BROWSER_CHROME_URL, "_blank",
                                                  features, defaultArgs);

        let onFullScreen = null;
        if (AppConstants.platform == "macosx") {
          onFullScreen = function(e) {
            newWindow.removeEventListener("fullscreen", onFullScreen);
            let docEl = newWindow.document.documentElement;
            let sizemode = docEl.getAttribute("sizemode");
            if (!newWindow.fullScreen && sizemode == "fullscreen") {
              docEl.setAttribute("sizemode", "normal");
              e.preventDefault();
              e.stopPropagation();
              return false;
            }
            return undefined;
          };
          newWindow.addEventListener("fullscreen", onFullScreen);
        }

        let promiseReady = new Promise(resolve => {
          // Window creation and destruction is asynchronous. We need to wait
          // until all existing windows are fully closed, and the new window is
          // fully open, before continuing. Otherwise the rest of the sanitizer
          // could run too early (and miss new cookies being set when a page
          // closes) and/or run too late (and not have a fully-formed window yet
          // in existence). See bug 1088137.
          let newWindowOpened = false;
          let onWindowOpened = function(subject, topic, data) {
            if (subject != newWindow)
              return;

            Services.obs.removeObserver(onWindowOpened, "browser-delayed-startup-finished");
            if (AppConstants.platform == "macosx") {
              newWindow.removeEventListener("fullscreen", onFullScreen);
            }
            newWindowOpened = true;
            // If we're the last thing to happen, invoke callback.
            if (numWindowsClosing == 0) {
              TelemetryStopwatch.finish("FX_SANITIZE_OPENWINDOWS", refObj);
              resolve();
            }
          };

          let numWindowsClosing = windowList.length;
          let onWindowClosed = function() {
            numWindowsClosing--;
            if (numWindowsClosing == 0) {
              Services.obs.removeObserver(onWindowClosed, "xul-window-destroyed");
              // If we're the last thing to happen, invoke callback.
              if (newWindowOpened) {
                TelemetryStopwatch.finish("FX_SANITIZE_OPENWINDOWS", refObj);
                resolve();
              }
            }
          };
          Services.obs.addObserver(onWindowOpened, "browser-delayed-startup-finished");
          Services.obs.addObserver(onWindowClosed, "xul-window-destroyed");
        });

        // Start the process of closing windows
        while (windowList.length) {
          windowList.pop().close();
        }
        newWindow.focus();
        await promiseReady;
      }
    },

    pluginData: {
      async clear(range) {
        await clearData(range, Ci.nsIClearDataService.CLEAR_PLUGIN_DATA);
      },
    },
  },
};

async function sanitizeInternal(items, aItemsToClear, progress, options = {}) {
  let { ignoreTimespan = true, range } = options;
  let seenError = false;
  // Shallow copy the array, as we are going to modify it in place later.
  if (!Array.isArray(aItemsToClear))
    throw new Error("Must pass an array of items to clear.");
  let itemsToClear = [...aItemsToClear];

  // Store the list of items to clear, in case we are killed before we
  // get a chance to complete.
  let uid = gPendingSanitizationSerial++;
  // Shutdown sanitization is managed outside.
  if (!progress.isShutdown)
    addPendingSanitization(uid, itemsToClear, options);

  // Store the list of items to clear, for debugging/forensics purposes
  for (let k of itemsToClear) {
    progress[k] = "ready";
  }

  // Ensure open windows get cleared first, if they're in our list, so that
  // they don't stick around in the recently closed windows list, and so we
  // can cancel the whole thing if the user selects to keep a window open
  // from a beforeunload prompt.
  let openWindowsIndex = itemsToClear.indexOf("openWindows");
  if (openWindowsIndex != -1) {
    itemsToClear.splice(openWindowsIndex, 1);
    await items.openWindows.clear(null, options);
    progress.openWindows = "cleared";
  }

  // If we ignore timespan, clear everything,
  // otherwise, pick a range.
  if (!ignoreTimespan && !range) {
    range = Sanitizer.getClearRange();
  }

  // For performance reasons we start all the clear tasks at once, then wait
  // for their promises later.
  // Some of the clear() calls may raise exceptions (for example bug 265028),
  // we catch and store them, but continue to sanitize as much as possible.
  // Callers should check returned errors and give user feedback
  // about items that could not be sanitized
  let refObj = {};
  TelemetryStopwatch.start("FX_SANITIZE_TOTAL", refObj);

  let annotateError = (name, ex) => {
    progress[name] = "failed";
    seenError = true;
    console.error("Error sanitizing " + name, ex);
  };

  // Array of objects in form { name, promise }.
  // `name` is the item's name and `promise` may be a promise, if the
  // sanitization is asynchronous, or the function return value, otherwise.
  let handles = [];
  for (let name of itemsToClear) {
    let item = items[name];
    try {
      // Catch errors here, so later we can just loop through these.
      handles.push({ name,
                     promise: item.clear(range, options)
                                  .then(() => progress[name] = "cleared",
                                        ex => annotateError(name, ex))
                   });
    } catch (ex) {
      annotateError(name, ex);
    }
  }
  for (let handle of handles) {
    progress[handle.name] = "blocking";
    await handle.promise;
  }

  // Sanitization is complete.
  TelemetryStopwatch.finish("FX_SANITIZE_TOTAL", refObj);
  if (!progress.isShutdown)
    removePendingSanitization(uid);
  progress = {};
  if (seenError) {
    throw new Error("Error sanitizing");
  }
}

async function sanitizeOnShutdown(progress) {
  if (Sanitizer.shouldSanitizeOnShutdown) {
    // Need to sanitize upon shutdown
    let itemsToClear = getItemsToClearFromPrefBranch(Sanitizer.PREF_SHUTDOWN_BRANCH);
    await Sanitizer.sanitize(itemsToClear, { progress });
  }

  // Clear out QuotaManager storage for principals that have been marked as
  // session only.  The cookie service has special logic that avoids writing
  // such cookies to disk, but QuotaManager always touches disk, so we need to
  // wipe the data on shutdown (or startup if we failed to wipe it at
  // shutdown).  (Note that some session cookies do survive Firefox restarts
  // because the Session Store that remembers your tabs between sessions takes
  // on the responsibility for persisting them through restarts.)
  //
  // The default value is determined by the "Browser Privacy" preference tab's
  // "Cookies and Site Data" "Accept cookies and site data from websites...Keep
  // until" setting.  The default is "They expire" (ACCEPT_NORMALLY), but it
  // can also be set to "PRODUCT is closed" (ACCEPT_SESSION).  A permission can
  // also be explicitly set on a per-origin basis from the Page Info's "Set
  // Cookies" row.
  //
  // We can think of there being two groups that might need to be wiped.
  // First, when the default is set to ACCEPT_SESSION, then all origins that
  // use QuotaManager storage but don't have a specific permission set to
  // ACCEPT_NORMALLY need to be wiped.  Second, the set of origins that have
  // the permission explicitly set to ACCEPT_SESSION need to be wiped.  There
  // are also other ways to think about and accomplish this, but this is what
  // the logic below currently does!
  await sanitizeSessionPrincipals();

  // Let's see if we have to forget some particular site.
  let enumerator = Services.perms.enumerator;
  while (enumerator.hasMoreElements()) {
    let permission = enumerator.getNext().QueryInterface(Ci.nsIPermission);
    if (permission.type == "cookie" && permission.capability == Ci.nsICookiePermission.ACCESS_SESSION) {
      await sanitizeSessionPrincipal(permission.principal);
    }
  }

  if (Sanitizer.shouldSanitizeNewTabContainer) {
    sanitizeNewTabSegregation();
    removePendingSanitization("newtab-container");
  }

  if (Sanitizer.shouldSanitizeOnShutdown) {
    // We didn't crash during shutdown sanitization, so annotate it to avoid
    // sanitizing again on startup.
    removePendingSanitization("shutdown");
    Services.prefs.savePrefFile(null);
  }
}

async function sanitizeSessionPrincipals() {
  if (Services.prefs.getIntPref(PREF_COOKIE_LIFETIME,
                                Ci.nsICookieService.ACCEPT_NORMALLY) != Ci.nsICookieService.ACCEPT_SESSION) {
    return;
  }

  let principals = await new Promise(resolve => {
    quotaManagerService.getUsage(request => {
      if (request.resultCode != Cr.NS_OK) {
        // We are probably shutting down. We don't want to propagate the
        // error, rejecting the promise.
        resolve([]);
        return;
      }

      let list = [];
      for (let item of request.result) {
        let principal = Services.scriptSecurityManager.createCodebasePrincipalFromOrigin(item.origin);
        let uri = principal.URI;
        if (uri.scheme == "http" || uri.scheme == "https" || uri.scheme == "file") {
          list.push(principal);
        }
      }
      resolve(list);
    });
  }).catch(() => []);

  let serviceWorkers = serviceWorkerManager.getAllRegistrations();
  for (let i = 0; i < serviceWorkers.length; i++) {
    let sw = serviceWorkers.queryElementAt(i, Ci.nsIServiceWorkerRegistrationInfo);
    principals.push(sw.principal);
  }

  await maybeSanitizeSessionPrincipals(principals);
}

// This method receives a list of principals and it checks if some of them need
// to be sanitize.
async function maybeSanitizeSessionPrincipals(principals) {
  let promises = [];

  for (let i = 0; i < principals.length; ++i) {
    let p = Services.perms.testPermissionFromPrincipal(principals[i], "cookie");
    if (p != Ci.nsICookiePermission.ACCESS_ALLOW &&
        p != Ci.nsICookiePermission.ACCESS_ALLOW_FIRST_PARTY_ONLY &&
        p != Ci.nsICookiePermission.ACCESS_LIMIT_THIRD_PARTY) {
      promises.push(sanitizeSessionPrincipal(principals[i]));
    }
  }

  return Promise.all(promises);
}

async function sanitizeSessionPrincipal(principal) {
  await new Promise(resolve => {
    Services.clearData.deleteDataFromPrincipal(principal, true /* user request */,
                                               Ci.nsIClearDataService.CLEAR_DOM_STORAGES,
                                               resolve);
  });
}

function sanitizeNewTabSegregation() {
  let identity = ContextualIdentityService.getPrivateIdentity("userContextIdInternal.thumbnail");
  if (identity) {
    Services.obs.notifyObservers(null, "clear-origin-attributes-data",
                                 JSON.stringify({ userContextId: identity.userContextId }));
  }
}

/**
 * Gets an array of items to clear from the given pref branch.
 * @param branch The pref branch to fetch.
 * @return Array of items to clear
 */
function getItemsToClearFromPrefBranch(branch) {
  branch = Services.prefs.getBranch(branch);
  return Object.keys(Sanitizer.items).filter(itemName => {
    try {
      return branch.getBoolPref(itemName);
    } catch (ex) {
      return false;
    }
  });
}

/**
 * These functions are used to track pending sanitization on the next startup
 * in case of a crash before a sanitization could happen.
 * @param id A unique id identifying the sanitization
 * @param itemsToClear The items to clear
 * @param options The Sanitize options
 */
function addPendingSanitization(id, itemsToClear, options) {
  let pendingSanitizations = safeGetPendingSanitizations();
  pendingSanitizations.push({id, itemsToClear, options});
  Services.prefs.setStringPref(Sanitizer.PREF_PENDING_SANITIZATIONS,
                               JSON.stringify(pendingSanitizations));
}
function removePendingSanitization(id) {
  let pendingSanitizations = safeGetPendingSanitizations();
  let i = pendingSanitizations.findIndex(s => s.id == id);
  let [s] = pendingSanitizations.splice(i, 1);
  Services.prefs.setStringPref(Sanitizer.PREF_PENDING_SANITIZATIONS,
    JSON.stringify(pendingSanitizations));
  return s;
}
function getAndClearPendingSanitizations() {
  let pendingSanitizations = safeGetPendingSanitizations();
  if (pendingSanitizations.length)
    Services.prefs.clearUserPref(Sanitizer.PREF_PENDING_SANITIZATIONS);
  return pendingSanitizations;
}
function safeGetPendingSanitizations() {
  try {
    return JSON.parse(
      Services.prefs.getStringPref(Sanitizer.PREF_PENDING_SANITIZATIONS, "[]"));
  } catch (ex) {
    Cu.reportError("Invalid JSON value for pending sanitizations: " + ex);
    return [];
  }
}

async function clearData(range, flags) {
  if (range) {
    await new Promise(resolve => {
      Services.clearData.deleteDataInTimeRange(range[0], range[1], true /* user request */,
                                               flags, resolve);
    });
  } else {
    await new Promise(resolve => {
      Services.clearData.deleteData(flags, resolve);
    });
  }
}