Issue 3687 - Add experimental support for Safari content blockers

safari/contentBlocking.js

Index: safari/contentBlocking.js
diff --git a/safari/contentBlocking.js b/safari/contentBlocking.js
new file mode 100644
index 0000000000000000000000000000000000000000..14f0b5b5ed9e3ecc9b7525c6bea526499bd35b43
--- /dev/null
+++ b/safari/contentBlocking.js
@@ -0,0 +1,162 @@
+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-2016 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @module contentBlocking */
+
+"use strict";
+
+let {Prefs} = require("prefs");
+let {ContentBlockerList} = require("abp2blocklist");
+let {FilterStorage} = require("filterStorage");
+let {FilterNotifier} = require("filterNotifier");
+let {port} = require("messaging");
+
+let contentBlockingSupported = "setContentBlocker" in safari.extension;
+let legacyAPISupported = new Promise(resolve =>
+{
+  function onLegacyAPISupported(msg, sender)
+  {
+    port.off("safari.legacyAPISupported", onLegacyAPISupported);
+    resolve(msg.legacyAPISupported);
+  }
+  port.on("safari.legacyAPISupported", onLegacyAPISupported);
+});
+let contentBlockingActive = false;
+let afterContentBlockingFinished = null;
+let contentBlockListDirty = true;
+let lastSetContentBlockerError;
+
+function clearBlockCounters()
+{
+  ext.pages.query({}, pages =>
+  {
+    for (let page of pages)
+      page.browserAction.setBadge();
+  });
+}
+
+function setContentBlocker(callback)
+{
+  // When given the same rules as last time setContentBlocker will always give
+  // null (success) to the callback, even when there was actually an error. We
+  // cache the last result therefore so that we can provide a consistent result
+  // and also to avoid wastefully regenerating an identical blocklist.
+  if (!contentBlockListDirty)
+  {
+    callback(lastSetContentBlockerError);
+    return;
+  }
+
+  let contentBlockerList = new ContentBlockerList();
+  for (let subscription of FilterStorage.subscriptions)
+    if (!subscription.disabled)
+      for (let filter of subscription.filters)
+        contentBlockerList.addFilter(filter);
+
+  contentBlockListDirty = false;
+  safari.extension.setContentBlocker(
+    // There is a strange bug in setContentBlocker for Safari 9 where if both
+    // the callback parameter is provided and the rules aren't converted to a
+    // JSON string it fails. Worse still it actually performs the callback twice
+    // too, firstly with an empty string and then with an Error:
+    //   "Extension compilation failed: Failed to parse the JSON String."
+    // To mitigate this we convert the rules to JSON here and also ignore
+    // callback values of "". (Usually the callback is performed with either
+    // null for success or an Error on failure.)
+    // Bug #26322821 filed on bugreport.apple.com
+    JSON.stringify(contentBlockerList.generateRules()),
+    function(error)
+    {
+      if (error === "")

[Sebastian Noack, 2016/05/18 08:13:37]

We always use == unless it makes a difference, as per Mozilla's coding
practices.

[kzar, 2016/05/18 09:28:47]

I wrongly thought that `(new Error("")).toString()` would result in an empty
string but actually it gives "Error". So I guess you're right that this can
never make a difference. Done.

[Sebastian Noack, 2016/05/18 10:07:24]

Even if error.toString() returns "", error == "" would still be false if error
is an object.

[Sebastian Noack, 2016/05/18 10:11:45]

Never mind, you are actually right that == calls the toString() method of
objects. But yeah in the case here it still doesn't matter.

+        return;
+
+      lastSetContentBlockerError = error;
+      callback(error);
+    }
+  );
+}
+
+function updateContentBlocker(isStartup, legacyAPISupported)
+{
+  afterContentBlockingFinished = new Promise(resolve =>
+  {
+    setContentBlocker(error =>
+    {
+      if (error instanceof Error)
+      {
+        let suppressErrorMessage = false;
+
+        // If the content blocking API fails the first time it's used the
+        // legacy blocking API (if available) won't have been disabled.
+        if (!contentBlockingActive && legacyAPISupported)
+        {
+          Prefs.safariContentBlocker = false;
+          // If content blocking failed on startup and we're switching back to
+          // the legacy API anyway we don't need to show an error message.
+          if (isStartup)
+            suppressErrorMessage = true;
+        }
+
+        if (!suppressErrorMessage)
+          alert(error.message);
+      }
+      else if (!contentBlockingActive)
+      {
+        contentBlockingActive = true;
+        clearBlockCounters();
+      }
+
+      resolve(contentBlockingActive);
+      afterContentBlockingFinished = null;
+    });
+  });
+}
+
+if (contentBlockingSupported)
+{
+  Promise.all([Prefs.untilLoaded,
+               FilterNotifier.once("load"),
+               legacyAPISupported]).then(resolvedValues =>
+  {
+    let legacyAPISupported = resolvedValues[2];
+    if (!legacyAPISupported)
+      Prefs.safariContentBlocker = true;
+
+    if (Prefs.safariContentBlocker)
+      updateContentBlocker(true, legacyAPISupported);
+
+    Prefs.on("safariContentBlocker", () =>
+    {
+      if (!contentBlockingActive && Prefs.safariContentBlocker)
+        updateContentBlocker(false, legacyAPISupported);
+    });
+
+    FilterNotifier.on("filter.behaviorChanged", () =>
+    {
+      contentBlockListDirty = true;
+      if (contentBlockingActive)
+        updateContentBlocker(false, legacyAPISupported);
+    });
+  });
+}
+
+port.on("safari.contentBlockingActive", (msg, sender) =>
+{
+  if (!contentBlockingActive && afterContentBlockingFinished)
+    return afterContentBlockingFinished;
+  return contentBlockingActive;
+});