Issue 6599 - Detect data corruption of storage.local

lib/subscriptionInit.js

Index: lib/subscriptionInit.js
===================================================================
--- a/lib/subscriptionInit.js
+++ b/lib/subscriptionInit.js
@@ -31,6 +31,7 @@
 const {Utils} = require("./utils");
 const {initNotifications} = require("./notificationHelper");
 const {updatesVersion} = require("../adblockplusui/lib/prefs");
+const {setUninstallURL} = require("./uninstall");
 
 let firstRun;
 let subscriptionsCallback = null;
@@ -225,7 +226,7 @@
   return subscriptions;
 }
 
-function finishInitialization(subscriptions)
+function addSubscriptionsAndNotifyUser(subscriptions)
 {
   if (subscriptionsCallback)
     subscriptions = subscriptionsCallback(subscriptions);
@@ -238,38 +239,42 @@
       Synchronizer.execute(subscription);
   }
 
-  if (!Prefs.suppress_first_run_page)
+  // Show first run page or the updates page. The latter is only shown
+  // on Chromium (since the current updates page announces features that
+  // aren't new to Firefox users), and only if this version of the
+  // updates page hasn't been shown yet.
+  if (firstRun || info.platform == "chromium" &&
+                  updatesVersion > Prefs.last_updates_page_displayed)
   {
-    let page = null;
-    if (firstRun)
-    {
-      page = "firstRun.html";
-    }
-    // For now we're limiting the updates page to users of
-    // Chromium-based browsers to gage its impact
-    else if (info.platform == "chromium" &&
-             updatesVersion > Prefs.last_updates_page_displayed)
+    return Prefs.set("last_updates_page_displayed", updatesVersion).catch(() =>
     {
-      page = "updates.html";
-    }
-
-    if (page)
+      exports.dataCorrupted = true;
+    }).then(() =>
     {
-      browser.tabs.create({url: browser.extension.getURL(page)});
-
-      // For new users and users that have already seen this updates page we
-      // want to avoid showing it again for subsequent updates.
-      Prefs.last_updates_page_displayed = updatesVersion;
-    }
+      if (!Prefs.suppress_first_run_page)
+      {
+        // Always show the first run page if a data corruption was detected
+        // (either though failure of reading from or writing to storage.local).
+        // The first run page notifies the user about the data corruption.
+        let url;
+        if (firstRun || exports.dataCorrupted)
+          url = "firstRun.html";
+        else
+          url = "updates.html";
+        browser.tabs.create({url});
+      }
+    });
   }
-
-  initNotifications();
 }
 
-Promise.all([FilterNotifier.once("load"),
-             Prefs.untilLoaded]).then(detectFirstRun)
-                                .then(getSubscriptions)
-                                .then(finishInitialization);
+Promise.all([
+  FilterNotifier.once("load"),
+  Prefs.untilLoaded.catch(() => { exports.dataCorrupted = true; })
+]).then(detectFirstRun)
+  .then(getSubscriptions)
+  .then(addSubscriptionsAndNotifyUser)
+  .then(setUninstallURL)
+  .then(initNotifications);
 
 /**
  * Indicates whether the default filter subscriptions have been added
@@ -281,6 +286,13 @@
 exports.reinitialized = false;
 
 /**
+ * Indicates whether a data corruption was detected.
+ *
+ * @type {boolean}
+ */
+exports.dataCorrupted = false;

[kzar, 2018/04/25 14:38:12]

I just realised that this should probably be a getter instead. Otherwise if it's
required directly the value won't update and that might not be obvious.

[Sebastian Noack, 2018/04/25 14:46:23]

Doesn't strike me as a huge issue. But more importantly it is consistent with
"reinitialized", and I'd rather not make this a getter without making
"reinitialized" a getter as well, but then we are going down a rabbit hole of
unrelated changes (also considering adblockplusui that relies on those).

[kzar, 2018/04/25 14:57:04]

Well I agree about not randomly changing "reinitialized" here, but not about not
making "dataCorrupted" a getter. To my mind "dataCorrupted" could change when we
detect that the data has been corrupted, even if we don't have such a check
implemented yet. Your example of not wanting to change code already used
elsewhere to / from a getter is a good example why we should make this a getter
now.

[Sebastian Noack, 2018/04/25 17:08:56]

I disagree about only changing either of them. So I turned both now into a
getter. I added Thomas CC, so that he knows that he has to account for those
changes in adblockplusui. FWIW, I couldn't test the latest patch set yet, will
do once there is a version of adblockplusui, I can test it with.

+
+/**
  * Sets a callback that is called with an array of subscriptions to be added
  * during initialization. The callback must return an array of subscriptions
  * that will effectively be added.