Issue 6538, 6781 - Allow snippets only from circumvention lists

lib/filterListener.js

Index: lib/filterListener.js
===================================================================
--- a/lib/filterListener.js
+++ b/lib/filterListener.js
@@ -29,16 +29,17 @@
 const {FilterNotifier} = require("./filterNotifier");
 const {ElemHide} = require("./elemHide");
 const {ElemHideEmulation} = require("./elemHideEmulation");
 const {Snippets} = require("./snippets");
 const {defaultMatcher} = require("./matcher");
 const {ActiveFilter, RegExpFilter,
        ElemHideBase, ElemHideEmulationFilter,
        SnippetFilter} = require("./filterClasses");
+const {SpecialSubscription} = require("./subscriptionClasses");
 const {Prefs} = require("prefs");
 
 /**
  * Increases on filter changes, filters will be saved if it exceeds 1.
  * @type {number}
  */
 let isDirty = 0;
 
@@ -135,37 +136,48 @@
  * @param {Filter} filter filter that has been added
  */
 function addFilter(filter)
 {
   if (!(filter instanceof ActiveFilter) || filter.disabled)
     return;
 
   let hasEnabled = false;
+  let allowSnippets = false;
   for (let i = 0; i < filter.subscriptions.length; i++)

[kzar, 2018/07/10 14:38:35]

Nit: `for (let subscription of filter.subscriptions)`

[Manish Jethani, 2018/07/10 18:33:22]

I did this initially and then reverted it. There's a similar loop in the
removeFilter function. The way I see it, this would be an unrelated change. I
think it should be done separately as a "no issue", also in the removeFilter
function.

[kzar, 2018/07/10 18:56:00]

Sure it's an unrelated change, but you're changing the entire loop anyway, it
seems crazy not to fix this at the same time IMO.

[Manish Jethani, 2018/07/11 15:07:03]

There are some performance implications of for..of [1] which really matters on
mobile. I would like to properly test/benchmark it and make the change in both
places.

[1]:
https://www.incredible-web.com/blog/performance-of-for-loops-with-javascript/

[kzar, 2018/07/11 17:22:07]

Fine.

   {
-    if (!filter.subscriptions[i].disabled)
+    let subscription = filter.subscriptions[i];
+
+    if (!subscription.disabled)
     {
       hasEnabled = true;
-      break;
+
+      // Allow snippets to be executed only by the circumvention lists or the
+      // user's own filters.
+      if (subscription.type == "circumvention" ||
+          subscription instanceof SpecialSubscription)
+      {
+        allowSnippets = true;
+        break;
+      }
     }
   }
   if (!hasEnabled)
     return;
 
   if (filter instanceof RegExpFilter)
     defaultMatcher.add(filter);
   else if (filter instanceof ElemHideBase)
   {
     if (filter instanceof ElemHideEmulationFilter)
       ElemHideEmulation.add(filter);
     else
       ElemHide.add(filter);
   }
-  else if (filter instanceof SnippetFilter)
+  else if (allowSnippets && filter instanceof SnippetFilter)
     Snippets.add(filter);
 }
 
 /**
  * Notifies Matcher instances or ElemHide object about removal of a filter
  * if necessary.
  * @param {Filter} filter filter that has been removed
  */