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/*
* Copyright (C) 2013 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:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef UnsafePersistent_h
#define UnsafePersistent_h
#include "bindings/v8/WrapperTypeInfo.h"
#include <v8.h>
namespace WebCore {
template<class KeyType> class DOMWrapperMap;
// An unsafe way to pass Persistent handles around. Do not use unless you know
// what you're doing. UnsafePersistent is only safe to use when we know that the
// memory pointed by the it is not going away: 1) When GC cannot happen while
// the UnsafePersistent is alive or 2) when there is a strong Persistent keeping
// the memory alive while the UnsafePersistent is alive.
template<typename T> class UnsafePersistent {
public:
UnsafePersistent() : m_value(0) { }
explicit UnsafePersistent(T* value) : m_value(value) { }
explicit UnsafePersistent(v8::Persistent<T>& handle)
{
m_value = handle.ClearAndLeak();
}
UnsafePersistent(v8::Isolate* isolate, v8::Handle<T>& handle)
{
v8::Persistent<T> persistent(isolate, handle);
m_value = persistent.ClearAndLeak();
}
T* value() const
{
return m_value;
}
template<typename V8T, typename U>
inline bool setReturnValueWithSecurityCheck(v8::ReturnValue<v8::Value> returnValue, U* object)
{
v8::Handle<v8::Object> result = deprecatedHandle();
// Security: always guard against malicious tampering.
RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(result.IsEmpty() || result->GetAlignedPointerFromInternalField(v8DOMWrapperObjectIndex) == V8T::toInternalPointer(object));
returnValue.Set(result);
return !result.IsEmpty();
}
inline bool setReturnValue(v8::ReturnValue<v8::Value> returnValue)
{
returnValue.Set(deprecatedHandle());
return !isEmpty();
}
// This is incredibly unsafe: the handle is valid only when this
// UnsafePersistent is alive and valid (see class level comment).
v8::Persistent<T>* persistent()
{
v8::Persistent<T>* handle = reinterpret_cast<v8::Persistent<T>*>(&m_value);
return handle;
}
void setReferenceFrom(const v8::Persistent<v8::Object>& parent, v8::Isolate* isolate)
{
isolate->SetReference(parent, *persistent());
}
void dispose()
{
persistent()->Reset();
m_value = 0;
}
void clear()
{
m_value = 0;
}
v8::Local<T> newLocal(v8::Isolate* isolate)
{
return v8::Local<T>::New(isolate, *persistent());
}
bool isEmpty() const
{
return !m_value;
}
private:
v8::Handle<T> deprecatedHandle()
{
v8::Handle<T>* handle = reinterpret_cast<v8::Handle<T>*>(&m_value);
return *handle;
}
T* m_value;
};
} // namespace WebCore
#endif // UnsafePersistent_h
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