[ServiceWorker] Add NULL check of ExecutionContext in FetchBodyStream::readAsync

Source/modules/serviceworkers/FetchBodyStream.cpp

 // Copyright 2014 The Chromium 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 "config.h"
 #include "modules/serviceworkers/FetchBodyStream.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/V8ThrowException.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/fileapi/Blob.h"
 #include "core/fileapi/FileReaderLoader.h"
 #include "core/fileapi/FileReaderLoaderClient.h"
 #include "modules/serviceworkers/ResponseInit.h"
 #include "platform/NotImplemented.h"
 #include "public/platform/WebServiceWorkerResponse.h"
 
 namespace blink {
 
 PassRefPtrWillBeRawPtr<FetchBodyStream> FetchBodyStream::create(ExecutionContext* context, PassRefPtr<BlobDataHandle> blobDataHandle)
 {
     RefPtrWillBeRawPtr<FetchBodyStream> fetchBodyStream(adoptRefWillBeNoop(new FetchBodyStream(context, blobDataHandle)));
     fetchBodyStream->suspendIfNeeded();
     return fetchBodyStream.release();
 }
 
 ScriptPromise FetchBodyStream::readAsync(ScriptState* scriptState, ResponseType type)
 {
     if (m_hasRead)

[haraken, 2014/09/04 08:13:03]

I think you should check m_scriptState->contextIsEmpty() here.

We normally follow the following programming rule:

class A {
  A(ScriptState* scriptState) : m_scriptState(scriptState) { }

  void someMethodTriggeredAsynchronously() {
    if (m_scriptState->contextIsEmpty())
      return;
    ScriptState::Scope scope(m_scriptState.get());
    // do the actual work.
  }

  RefPtr<ScriptState> m_scriptState;
};

[horo, 2014/09/04 09:54:28]

Done.

         return ScriptPromise::reject(scriptState, V8ThrowException::createTypeError("Already read", scriptState->isolate()));
 
     m_hasRead = true;
     m_responseType = type;
 
     ASSERT(!m_resolver);
     m_resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = m_resolver->promise();
 
     FileReaderLoader::ReadType readType = FileReaderLoader::ReadAsText;
@@ skipping 18 matching lines @@
         // FIXME: Implement this.
         ASSERT_NOT_REACHED();
         break;
     case ResponseAsJSON:
     case ResponseAsText:
         break;
     default:
         ASSERT_NOT_REACHED();
     }
 
+    ExecutionContext* executionContext = scriptState->executionContext();
+    if (!executionContext) {
+        m_resolver->reject(V8ThrowException::createTypeError("ExecutionContext terminated", scriptState->isolate()));
+        m_resolver.clear();
+        return promise;
+    }
+
     m_loader = adoptPtr(new FileReaderLoader(readType, this));
-    m_loader->start(scriptState->executionContext(), m_blobDataHandle);
+    m_loader->start(executionContext, m_blobDataHandle);
 
     return promise;
 }
 
 ScriptPromise FetchBodyStream::asArrayBuffer(ScriptState* scriptState)
 {
     return readAsync(scriptState, ResponseAsArrayBuffer);
 }
 
 ScriptPromise FetchBodyStream::asBlob(ScriptState* scriptState)
@@ skipping 97 matching lines @@
 {
     ASSERT(m_resolver);
     if (!m_resolver->executionContext() || m_resolver->executionContext()->activeDOMObjectsAreStopped())
         return;
 
     m_resolver->resolve("");
     m_resolver.clear();
 }
 
 } // namespace blink