Issue 7236 - Handle sub properties in abort-on-property snippets

lib/content/snippets.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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
@@ skipping 680 matching lines @@
 function randomId()
 {
   // 2176782336 is 36^6 which mean 6 chars [a-z0-9]
   // 60466176 is 36^5
   // 2176782336 - 60466176 = 2116316160. This ensure to always have 6
   // chars even if Math.random() returns its minimum value 0.0
   //
   return Math.floor(Math.random() * 2116316160 + 60466176).toString(36);
 }
 
-function wrapPropertyAccess(object, property, descriptor)
+function wrapPropertyAccess(object, property, descriptor, magic)
 {
-  let currentDescriptor = Object.getOwnPropertyDescriptor(object, property);
-  if (currentDescriptor && !currentDescriptor.configurable)
-    return false;
+  let dot = property.indexOf(".");
+  if (dot == -1)
+  {
+    // simple property case.
+    let currentDescriptor = Object.getOwnPropertyDescriptor(object, property);
+    if (currentDescriptor && !currentDescriptor.configurable)
+      return false;
 
-  Object.defineProperty(object, property, descriptor);
-  return true;
+    Object.defineProperty(object, property, descriptor);
+    return true;
+  }
+  let name = property.slice(0, dot);
+  property = property.slice(dot + 1);
+  let value = object[name];
+  if (value && typeof value == "object")
+    return wrapPropertyAccess(value, property, descriptor);

[Manish Jethani, 2019/02/05 14:47:17]

Don't we have to pass along magic here?

[hub, 2019/02/05 15:20:20]

Yes we do. 

Done.

+
+  let currentDescriptor = Object.getOwnPropertyDescriptor(object, name);
+  if (currentDescriptor && currentDescriptor.set &&
+      magic && currentDescriptor.set.hasOwnProperty(magic))

[Manish Jethani, 2019/02/05 14:47:17]

Here check for magic being truthy seems redundant (unless it's for performance
reasons). `currentDescriptor.set.hasOwnProperty(magic)` will be `false` if
`magic` is falsy.

[hub, 2019/02/05 15:20:20]

might as well remove it. It's a corner case anyway.

+  {
+    return true;
+  }
+
+  let v;
+  let setter = a =>
+  {
+    v = a;
+    if (a && typeof a == "object")
+      wrapPropertyAccess(a, property, descriptor, magic);
+  };
+  setter[magic] = undefined;
+  Object.defineProperty(object, name, {get: () => v, set: setter});
 }

[Manish Jethani, 2019/02/05 14:47:17]

What about the return value here?

[hub, 2019/02/05 15:20:20]

Done.

 
 /**
  * Overrides the <code>onerror</code> handler to discard tagged error messages
  * from our property wrapping.
  *
  * @param {string} magic The magic string that tags the error message.
  */
 function overrideOnError(magic)
 {
   let {onerror} = window;
@@ skipping 22 matching lines @@
   if (!property)
     return;
 
   let rid = randomId();
 
   function abort()
   {
     throw new ReferenceError(rid);
   }
 
-  if (wrapPropertyAccess(window, property, {get: abort, set() {}}))
+  if (wrapPropertyAccess(window, property, {get: abort, set() {}}, rid))
     overrideOnError(rid);
 }
 
 exports["abort-on-property-read"] = makeInjector(abortOnPropertyRead,
                                                  wrapPropertyAccess,
                                                  overrideOnError,
                                                  randomId);
 
 /**
  * Patches a property on the window object to abort execution when the
@@ skipping 11 matching lines @@
   if (!property)
     return;
 
   let rid = randomId();
 
   function abort()
   {
     throw new ReferenceError(rid);
   }
 
-  if (wrapPropertyAccess(window, property, {set: abort}))
+  if (wrapPropertyAccess(window, property, {set: abort}, rid))
     overrideOnError(rid);
 }
 
 exports["abort-on-property-write"] = makeInjector(abortOnPropertyWrite,
                                                   wrapPropertyAccess,
                                                   overrideOnError,
                                                   randomId);
 
 /**
  * Aborts the execution of an inline script.
@@ skipping 42 matching lines @@
       abort();
       return currentValue;
     },
     set(value)
     {
       abort();
       currentValue = value;
     }
   };
 
-  if (wrapPropertyAccess(object, name, descriptor))
+  if (wrapPropertyAccess(object, name, descriptor, rid))
     overrideOnError(rid);
 }
 
 exports["abort-current-inline-script"] =
   makeInjector(abortCurrentInlineScript, wrapPropertyAccess, toRegExp,
                overrideOnError, regexEscape, randomId);