Bug 1277801 - Introduce Cu.isOpaqueWrapper. r=peterv

With the following changes Object.prototype.toString is not using the JSClass' name
anymore. This means we now fail to detect opaque wrappers, because they just get the default string: [object Object]

Differential Revision: https://phabricator.services.mozilla.com/D74016

js/xpconnect/idl/xpccomponents.idl

@@ -524,6 +524,11 @@ interface nsIXPCComponents_Utils : nsISupports
     [implicit_jscontext]
     void unblockScriptForGlobal(in jsval global);
 
+    /**
+     * Check whether the given object is an opaque wrapper (PermissiveXrayOpaque).
+     */
+    bool isOpaqueWrapper(in jsval obj);
+
     /**
      * Check whether the given object is an XrayWrapper.
      */

js/xpconnect/src/XPCComponents.cpp

@@ -2153,6 +2153,13 @@ nsXPCComponents_Utils::UnblockScriptForGlobal(HandleValue globalArg,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsXPCComponents_Utils::IsOpaqueWrapper(HandleValue obj, bool* aRetval) {
+  *aRetval =
+      obj.isObject() && xpc::WrapperFactory::IsOpaqueWrapper(&obj.toObject());
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsXPCComponents_Utils::IsXrayWrapper(HandleValue obj, bool* aRetval) {
   *aRetval =

js/xpconnect/tests/chrome/test_xrayToJS.xhtml

@@ -78,8 +78,8 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=933681
          "we end up with the appropriate constructor: " + c);
       is(Cu.unwaiveXrays(Cu.waiveXrays(new iwin[c](...args)).constructor), iwin[c],
          "constructor property is set up right: " + c);
-      let expectedProto = /Opaque/.test(new iwin[c](...args)) ? iwin['Object'].prototype
-                                                     : iwin[c].prototype;
+      let expectedProto = Cu.isOpaqueWrapper(new iwin[c](...args)) ?
+        iwin['Object'].prototype : iwin[c].prototype;
       is(Object.getPrototypeOf(new iwin[c](...args)), expectedProto,
          "prototype is correct: " + c);
       is(global(new iwin[c](...args)), iwin, "Got the right global: " + c);
@@ -148,8 +148,8 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=933681
          "we end up with the appropriate AggregateError constructor");
       is(Cu.unwaiveXrays(Cu.waiveXrays(new iwin.AggregateError(...args)).constructor), iwin.AggregateError,
          "AggregateError constructor property is set up right");
-      let expectedProto = /Opaque/.test(new iwin.AggregateError(...args)) ? iwin['Object'].prototype
-                                                                          : iwin.AggregateError.prototype;
+      let expectedProto =  Cu.isOpaqueWrapper(new iwin.AggregateError(...args)) ?
+        iwin['Object'].prototype : iwin.AggregateError.prototype;
       is(Object.getPrototypeOf(new iwin.AggregateError(...args)), expectedProto,
          "AggregateError prototype is correct");
       is(global(new iwin.AggregateError(...args)), iwin, "Got the right global for AggregateError");
@@ -383,11 +383,11 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=933681
         is(method.call(xray) + "", local.call(xray) + "",
            "Xray and local method results stringify identically");
 
-        // If invoking this method returns something non-Xrayable, the
-        // stringification is going to return [object Opaque].
+        // If invoking this method returns something non-Xrayable (opaque), the
+        // stringification is going to return [object Object].
         // This happens for set[@@iterator] and other Iterator objects.
         let callable = lookupCallable(xray.wrappedJSObject);
-        if (!/Opaque/.test(method.call(xray)) && callable) {
+        if (!Cu.isOpaqueWrapper(method.call(xray)) && callable) {
           is(method.call(xray) + "",
              callable.call(xray.wrappedJSObject) + "",
              "Xray and waived method results stringify identically");

js/xpconnect/wrappers/WrapperFactory.cpp

@@ -44,6 +44,11 @@ const Wrapper XrayWaiver(WrapperFactory::WAIVE_XRAY_WRAPPER_FLAG);
 // off it.
 const WaiveXrayWrapper WaiveXrayWrapper::singleton(0);
 
+bool WrapperFactory::IsOpaqueWrapper(JSObject* obj) {
+  return IsWrapper(obj) &&
+         Wrapper::wrapperHandler(obj) == &PermissiveXrayOpaque::singleton;
+}
+
 bool WrapperFactory::IsCOW(JSObject* obj) {
   return IsWrapper(obj) &&
          Wrapper::wrapperHandler(obj) == &ChromeObjectWrapper::singleton;

js/xpconnect/wrappers/WrapperFactory.h

@@ -67,6 +67,8 @@ class WrapperFactory {
             js::GetProxyHandler(obj) == &CrossOriginObjectWrapper::singleton);
   }
 
+  static bool IsOpaqueWrapper(JSObject* obj);
+
   static bool HasWaiveXrayFlag(JSObject* wrapper) {
     return HasWrapperFlag(wrapper, WAIVE_XRAY_WRAPPER_FLAG);
   }