1 files changed, 150 insertions, 0 deletions
diff --git a/b2g/components/SafeMode.jsm b/b2g/components/SafeMode.jsm
new file mode 100644
index 000000000..9f9342f67
--- /dev/null
+++ b/b2g/components/SafeMode.jsm
@@ -0,0 +1,150 @@
+/* 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";
+
+this.EXPORTED_SYMBOLS = ["SafeMode"];
+
+const Cu = Components.utils;
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/AppConstants.jsm");
+
+const kSafeModePref = "b2g.safe_mode";
+const kSafeModePage = "safe_mode.html";
+
+function debug(aStr) {
+  //dump("-*- SafeMode: " + aStr + "\n");
+}
+
+// This module is responsible for checking whether we want to start in safe
+// mode or not. The flow is as follow:
+// - wait for the `b2g.safe_mode` preference to be set to something different
+//   than `unset` by nsAppShell
+// - If it's set to `no`, just start normally.
+// - If it's set to `yes`, we load a stripped down system app from safe_mode.html"
+//   - This page is responsible to dispatch a mozContentEvent to us.
+//   - If the user choose SafeMode, we disable all add-ons.
+//   - We go on with startup.
+
+this.SafeMode = {
+  // Returns a promise that resolves when nsAppShell has set the
+  // b2g.safe_mode_state_ready preference to `true`.
+  _waitForPref: function() {
+    debug("waitForPref");
+    try {
+      let currentMode = Services.prefs.getCharPref(kSafeModePref);
+      debug("current mode: " + currentMode);
+      if (currentMode !== "unset") {
+        return Promise.resolve();
+      }
+    } catch(e) { debug("No current mode available!"); }
+
+    // Wait for the preference to toggle.
+    return new Promise((aResolve, aReject) => {
+      let observer = function(aSubject, aTopic, aData) {
+        if (Services.prefs.getCharPref(kSafeModePref)) {
+          Services.prefs.removeObserver(kSafeModePref, observer, false);
+          aResolve();
+        }
+      }
+
+      Services.prefs.addObserver(kSafeModePref, observer, false);
+    });
+  },
+
+  // Resolves once the user has decided how to start.
+  // Note that all the actions happen here, so there is no other action from
+  // consumers than to go on.
+  _waitForUser: function() {
+    debug("waitForUser");
+    let isSafeMode = Services.prefs.getCharPref(kSafeModePref) === "yes";
+    if (!isSafeMode) {
+      return Promise.resolve();
+    }
+    debug("Starting in Safe Mode!");
+
+    // Load $system_app/safe_mode.html as a full screen iframe, and wait for
+    // the user to make a choice.
+    let shell = SafeMode.window.shell;
+    let document = SafeMode.window.document;
+    SafeMode.window.screen.mozLockOrientation("portrait");
+
+    let url = Services.io.newURI(shell.homeURL, null, null)
+                         .resolve(kSafeModePage);
+    debug("Registry is ready, loading " + url);
+    let frame = document.createElementNS("http://www.w3.org/1999/xhtml", "html:iframe");
+    frame.setAttribute("mozbrowser", "true");
+    frame.setAttribute("mozapp", shell.manifestURL);
+    frame.setAttribute("id", "systemapp"); // To keep screen.js happy.
+    let contentBrowser = document.body.appendChild(frame);
+
+    return new Promise((aResolve, aReject) => {
+      let content = contentBrowser.contentWindow;
+
+      // Stripped down version of the system app bootstrap.
+      function handleEvent(e) {
+        switch(e.type) {
+          case "mozbrowserloadstart":
+            if (content.document.location == "about:blank") {
+              contentBrowser.addEventListener("mozbrowserlocationchange", handleEvent, true);
+              contentBrowser.removeEventListener("mozbrowserloadstart", handleEvent, true);
+              return;
+            }
+
+            notifyContentStart();
+            break;
+          case "mozbrowserlocationchange":
+            if (content.document.location == "about:blank") {
+              return;
+            }
+
+            contentBrowser.removeEventListener("mozbrowserlocationchange", handleEvent, true);
+            notifyContentStart();
+            break;
+          case "mozContentEvent":
+            content.removeEventListener("mozContentEvent", handleEvent, true);
+            contentBrowser.parentNode.removeChild(contentBrowser);
+
+            if (e.detail == "safemode-yes")  {
+              // Really starting in safe mode, let's disable add-ons first.
+              // TODO: disable add-ons
+              aResolve();
+            } else {
+              aResolve();
+            }
+            break;
+        }
+      }
+
+      function notifyContentStart() {
+        let window = SafeMode.window;
+        window.shell.sendEvent(window, "SafeModeStart");
+        contentBrowser.setVisible(true);
+
+        // browser-ui-startup-complete is used by the AppShell to stop the
+        // boot animation and start gecko rendering.
+        Services.obs.notifyObservers(null, "browser-ui-startup-complete", "");
+        content.addEventListener("mozContentEvent", handleEvent, true);
+      }
+
+      contentBrowser.addEventListener("mozbrowserloadstart", handleEvent, true);
+      contentBrowser.src = url;
+    });
+  },
+
+  // Returns a Promise that resolves once we have decided to run in safe mode
+  // or not. All the safe mode switching actions happen before resolving the
+  // promise.
+  check: function(aWindow) {
+    debug("check");
+    this.window = aWindow;
+    if (AppConstants.platform !== "gonk") {
+      // For now we only have gonk support.
+      return Promise.resolve();
+    }
+
+    return this._waitForPref().then(this._waitForUser);
+  }
+}