Fix receiver checks for v8::Function on a remote context.

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 4476 matching lines @@
   RETURN_ON_FAILED_EXECUTION_PRIMITIVE(bool);
   return Just(true);
 }
 
 
 bool v8::Object::SetPrototype(Local<Value> value) {
   auto context = ContextFromHeapObject(Utils::OpenHandle(this));
   return SetPrototype(context, value).FromMaybe(false);
 }
 
-static bool HasInstanceInGlobalProxy(i::JSGlobalProxy* global_proxy,
-                                     i::FunctionTemplateInfo* target_template) {
-  auto* constructor_object = global_proxy->map()->GetConstructor();
-  if (!constructor_object->IsJSFunction()) return false;
-
-  auto* constructor = i::JSFunction::cast(constructor_object);
-  if (!constructor->shared()->function_data()->IsFunctionTemplateInfo())
-    return false;
-
-  auto* proxy_constructor_template =
-      i::FunctionTemplateInfo::cast(constructor->shared()->function_data());
-  if (!proxy_constructor_template->prototype_template()->IsObjectTemplateInfo())
-    return false;
-
-  auto* global_template = i::ObjectTemplateInfo::cast(
-      proxy_constructor_template->prototype_template());
-  // Iterate through the chain of inheriting function templates to
-  // see if the required one occurs.
-  for (i::Object* type = global_template->constructor();
-       type->IsFunctionTemplateInfo();
-       type = i::FunctionTemplateInfo::cast(type)->parent_template()) {
-    if (type == target_template) return true;
-  }
-  // Didn't find the required type in the inheritance chain.
-  return false;
-}
-
 Local<Object> v8::Object::FindInstanceInPrototypeChain(
     v8::Local<FunctionTemplate> tmpl) {
   auto self = Utils::OpenHandle(this);
   auto isolate = self->GetIsolate();
   i::PrototypeIterator iter(isolate, *self, i::kStartAtReceiver);
   auto tmpl_info = *Utils::OpenHandle(*tmpl);
   while (!tmpl_info->IsTemplateFor(iter.GetCurrent<i::JSObject>())) {
     iter.Advance();
-    if (iter.IsAtEnd()) {
-      // Normally, a standard prototype walk is sufficient; however, global
-      // proxies aren't directly constructed with the supplied template.
-      // Normally, this is not a problem, because the prototype chain includes
-      // the global object; however, a remote context has no global object.
-      if (self->IsJSGlobalProxy() &&
-          HasInstanceInGlobalProxy(i::JSGlobalProxy::cast(*self), tmpl_info))
-        return Utils::ToLocal(self);
-      return Local<Object>();
-    }
+    if (iter.IsAtEnd()) return Local<Object>();
     if (!iter.GetCurrent()->IsJSObject()) return Local<Object>();
   }
   // IsTemplateFor() ensures that iter.GetCurrent() can't be a Proxy here.
   return Utils::ToLocal(i::handle(iter.GetCurrent<i::JSObject>(), isolate));
 }
 
 MaybeLocal<Array> v8::Object::GetPropertyNames(Local<Context> context) {
   return GetPropertyNames(
       context, v8::KeyCollectionMode::kIncludePrototypes,
       static_cast<v8::PropertyFilter>(ONLY_ENUMERABLE | SKIP_SYMBOLS),
@@ skipping 2046 matching lines @@
   return Utils::ToLocal(scope.CloseAndEscape(object));
 }
 
 bool FunctionTemplate::HasInstance(v8::Local<v8::Value> value) {
   auto self = Utils::OpenHandle(this);
   auto obj = Utils::OpenHandle(*value);
   if (obj->IsJSObject() && self->IsTemplateFor(i::JSObject::cast(*obj))) {
     return true;
   }
   if (obj->IsJSGlobalProxy()) {
-    auto* global_proxy = i::JSGlobalProxy::cast(*obj);
-    // For global proxies, check the constructor's prototype instead. Remote
-    // global proxies have no global object to perform instance checks on, but
-    // the constructor's prototype's constructor corresponds to the original
-    // template used to create the context.
-    return HasInstanceInGlobalProxy(global_proxy, *self);
+    // If it's a global proxy object, then test with the global object.
+    i::PrototypeIterator iter(i::JSObject::cast(*obj)->map());
+    if (iter.IsAtEnd()) return false;

[jochen (gone - plz use gerrit), 2017/02/22 09:03:14]

how can this happen? Shouldn't there now always be the placeholder?

[dcheng, 2017/02/22 09:29:53]

I was reverting this to the original version, but I think the only time this
would be null is if the JSGlobalProxy is detached. However, calling
HasInstance() in that case should be a bug, so I changed this to a DCHECK

+    return self->IsTemplateFor(iter.GetCurrent<i::JSObject>());
   }
   return false;
 }
 
 
 Local<External> v8::External::New(Isolate* isolate, void* value) {
   STATIC_ASSERT(sizeof(value) == sizeof(i::Address));
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   LOG_API(i_isolate, External, New);
   ENTER_V8_NO_SCRIPT_NO_EXCEPTION(i_isolate);
@@ skipping 3656 matching lines @@
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 }  // namespace internal
 }  // namespace v8