Make messageHandlerInMainThread support main-thread worklets.

third_party/WebKit/Source/bindings/core/v8/V8Initializer.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 93 matching lines @@
     // Currently stack trace is only collected when inspector is open.
     if (!stackTrace.IsEmpty() && stackTrace->GetFrameCount() > 0) {
         callStack = ScriptCallStack::create(isolate, stackTrace);
         int topScriptId = stackTrace->GetFrame(0)->GetScriptId();
         if (topScriptId == *scriptId)
             *scriptId = 0;
     }
     return callStack.release();
 }
 
-static String extractResourceName(v8::Local<v8::Message> message, const Document* document)
+static String extractResourceName(v8::Local<v8::Message> message, const ExecutionContext* context)
 {
     v8::Local<v8::Value> resourceName = message->GetScriptOrigin().ResourceName();
-    bool shouldUseDocumentURL = document && (resourceName.IsEmpty() || !resourceName->IsString());
-    return shouldUseDocumentURL ? document->url() : toCoreString(resourceName.As<v8::String>());
+    bool shouldUseDocumentURL = context && context->isDocument() && (resourceName.IsEmpty() || !resourceName->IsString());
+    return shouldUseDocumentURL ? context->url() : toCoreString(resourceName.As<v8::String>());
 }
 
 static String extractMessageForConsole(v8::Isolate* isolate, v8::Local<v8::Value> data)
 {
     if (V8DOMWrapper::isWrapper(isolate, data)) {
         v8::Local<v8::Object> obj = v8::Local<v8::Object>::Cast(data);
         const WrapperTypeInfo* type = toWrapperTypeInfo(obj);
         if (V8DOMException::wrapperTypeInfo.isSubclass(type)) {
             DOMException* exception = V8DOMException::toImpl(obj);
             if (exception && !exception->messageForConsole().isEmpty())
@@ skipping 10 matching lines @@
     int columnNumber = 0;
     if (v8Call(message->GetLineNumber(scriptState->context()), lineNumber)
         && v8Call(message->GetStartColumn(scriptState->context()), columnNumber))
         ++columnNumber;
     return ErrorEvent::create(errorMessage, resourceName, lineNumber, columnNumber, &scriptState->world());
 }
 
 static void messageHandlerInMainThread(v8::Local<v8::Message> message, v8::Local<v8::Value> data)
 {
     ASSERT(isMainThread());
+
     v8::Isolate* isolate = v8::Isolate::GetCurrent();
-    // If called during context initialization, there will be no entered window.
+    ScriptState* scriptState = ScriptState::current(isolate);
+    ExecutionContext* context = scriptState->getExecutionContext();
+
+    // If called during context initialization, there will be no entered context.
     // TODO(haraken): Add a helper method to get an entered window that may be null.
-    LocalDOMWindow* enteredWindow = toLocalDOMWindow(toDOMWindow(isolate->GetEnteredContext()));
-    if (!enteredWindow || !enteredWindow->isCurrentlyDisplayedInFrame())
+    if (!context)
+        return;
+
+    if (context->isDocument() && !toDocument(context)->domWindow()->isCurrentlyDisplayedInFrame())

[ikilpatrick, 2016/04/13 04:21:09]

Is toDocument(context)->domWindow() safe? (non-null? and equivalent to before?)

[haraken, 2016/04/13 04:38:48]

This can change existing behavior because the entered window can be different
from the ScriptState::current()->getExecutionContext()->domWindow()...

Hmm. It looks like that the current code is wrong anyway. It is mixing
ScriptState::current() and enteredWindow, which are different things...

OK. My proposal is:

- Stop using the entered window. Always use ScriptState::current(). (Actually I
don't know why we've been using the entered window.)

- Add the following check:

ScriptState* scriptState = ScriptState::current(isolate);
if (!scriptState->contextIsValid())  // This check is essentially the same as
the isCurrentlyDisplayedInFrame check.
  return scriptState;

...;  // Use scriptState as you like.

[ikilpatrick, 2016/04/13 23:26:53]

Done. Tried to clean up the other ScriptState checks as well. Now sufficiently
scared about this code :).

         return;
 
     int scriptId = 0;
     RefPtr<ScriptCallStack> callStack = extractCallStack(isolate, message, &scriptId);
 
     AccessControlStatus accessControlStatus = NotSharableCrossOrigin;
     if (message->IsOpaque())
         accessControlStatus = OpaqueResource;
     else if (message->IsSharedCrossOrigin())
         accessControlStatus = SharableCrossOrigin;
 
-    ScriptState* scriptState = ScriptState::current(isolate);
-
-    String resourceName = extractResourceName(message, enteredWindow->document());
+    String resourceName = extractResourceName(message, context);
     ErrorEvent* event = createErrorEventFromMesssage(scriptState, message, resourceName);
 
     String messageForConsole = extractMessageForConsole(isolate, data);
     if (!messageForConsole.isEmpty())
         event->setUnsanitizedMessage("Uncaught " + messageForConsole);
 
     // This method might be called while we're creating a new context. In this case, we
     // avoid storing the exception object, as we can't create a wrapper during context creation.
     // FIXME: Can we even get here during initialization now that we bail out when GetEntered returns an empty handle?
-    LocalFrame* frame = enteredWindow->document()->frame();
-    if (frame && frame->script().existingWindowProxy(scriptState->world())) {
-        V8ErrorHandler::storeExceptionOnErrorEventWrapper(scriptState, event, data, scriptState->context()->Global());
+    if (context->isDocument()) {
+        LocalFrame* frame = toDocument(context)->frame();
+        if (frame && frame->script().existingWindowProxy(scriptState->world())) {
+            V8ErrorHandler::storeExceptionOnErrorEventWrapper(scriptState, event, data, scriptState->context()->Global());
+        }
     }
 
     if (scriptState->world().isPrivateScriptIsolatedWorld()) {
         // We allow a private script to dispatch error events even in a EventDispatchForbiddenScope scope.
         // Without having this ability, it's hard to debug the private script because syntax errors
         // in the private script are not reported to console (the private script just crashes silently).
         // Allowing error events in private scripts is safe because error events don't propagate to
         // other isolated worlds (which means that the error events won't fire any event listeners
         // in user's scripts).
         EventDispatchForbiddenScope::AllowUserAgentEvents allowUserAgentEvents;
-        enteredWindow->document()->reportException(event, scriptId, callStack, accessControlStatus);
+        context->reportException(event, scriptId, callStack, accessControlStatus);
     } else {
-        enteredWindow->document()->reportException(event, scriptId, callStack, accessControlStatus);
+        context->reportException(event, scriptId, callStack, accessControlStatus);
     }
 }
 
 namespace {
 
 static RejectedPromises& rejectedPromisesOnMainThread()
 {
     ASSERT(isMainThread());
     DEFINE_STATIC_LOCAL(RefPtr<RejectedPromises>, rejectedPromises, (RejectedPromises::create()));
     return *rejectedPromises;
@@ skipping 256 matching lines @@
 
     isolate->AddMessageListener(messageHandlerInWorker);
     isolate->SetFatalErrorHandler(reportFatalErrorInWorker);
 
     uint32_t here;
     isolate->SetStackLimit(reinterpret_cast<uintptr_t>(&here - kWorkerMaxStackSize / sizeof(uint32_t*)));
     isolate->SetPromiseRejectCallback(promiseRejectHandlerInWorker);
 }
 
 } // namespace blink