[SharedArrayBuffer] Prevent SharedArrayBuffer being used in Web APIs

third_party/WebKit/Source/core/dom/NotShared.h

+// Copyright 2017 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.
+
+#ifndef NotShared_h
+#define NotShared_h
+
+// A wrapper template type that is used to ensure that a TypedArray is not
+// backed by a SharedArrayBuffer.
+//
+// Typically this is used as an annotation on C++ functions that are called by
+// the bindings layer, e.g.:
+//
+//   void Foo(NotShared<DOMUint32Array> param) {
+//     DOMUint32Array* array = param.view();
+//     ...
+//   }
+
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+template <typename T>
+class CORE_EXPORT NotShared {
+  STACK_ALLOCATED();
+
+ public:
+  using TypedArrayType = T;
+
+  NotShared() {}
+
+  explicit NotShared(T* typedArray) : m_typedArray(typedArray) {
+    DCHECK(!(typedArray && typedArray->view()->isShared()));
+  }
+  NotShared(const NotShared& other) = default;
+  template <typename U>
+  NotShared(const NotShared<U>& other) : m_typedArray(other.view()) {}
+  template <typename U>
+  NotShared(const Member<U>& other) {
+    DCHECK(!other->view()->isShared());
+    m_typedArray = *other;
+  }
+
+  NotShared& operator=(const NotShared& other) = default;
+  template <typename U>
+  NotShared& operator=(const NotShared<U>& other) {
+    m_typedArray = other.view();
+    return *this;
+  }
+
+  T* view() const { return m_typedArray.get(); }
+
+  bool operator!() const { return !m_typedArray; }
+  explicit operator bool() const { return !!m_typedArray; }
+
+ private:
+  Member<T> m_typedArray;
+};
+
+}  // namespace blink
+
+namespace WTF {
+
+template <typename T>
+inline T* getPtr(const ::blink::NotShared<T>& p) {

[haraken, 2017/04/09 14:11:45]

Is this needed?

[binji, 2017/04/09 23:42:27]

It was used by a WaveShaperNode attribute getter, but I modified v8_attributes
to prevent using WTF::getPtr in that case.

+  return p.view();
+}
+
+}  // namespace WTF
+
+#endif  // NotShared_h