// Copyright 2020 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.

#ifndef V8_SANDBOX_EXTERNAL_POINTER_H_

#define V8_SANDBOX_EXTERNAL_POINTER_H_

#include "src/common/globals.h"

#include "src/sandbox/isolate.h"

namespace v8 {

namespace internal {

template <ExternalPointerTag tag>

class ExternalPointerMember {

public:

ExternalPointerMember() = default;

void Init(Address host_address, IsolateForSandbox isolate, Address value);

inline Address load(const IsolateForSandbox isolate) const;

inline void store(IsolateForSandbox isolate, Address value);

inline ExternalPointer_t load_encoded() const;

inline void store_encoded(ExternalPointer_t value);

Address storage_address() { return reinterpret_cast<Address>(storage_); }

private:

alignas(alignof(Tagged_t)) char storage_[sizeof(ExternalPointer_t)];

};

// Writes the null handle or kNullAddress into the external pointer field.

V8_INLINE void InitLazyExternalPointerField(Address field_address);

// Creates and initializes an entry in the external pointer table and writes the

// handle for that entry to the field.

template <ExternalPointerTag tag>

V8_INLINE void InitExternalPointerField(Address host_address,

Address field_address,

IsolateForSandbox isolate,

Address value);

// If the sandbox is enabled: reads the ExternalPointerHandle from the field and

// loads the corresponding external pointer from the external pointer table. If

// the sandbox is disabled: load the external pointer from the field.

//

// This can be used for both regular and lazily-initialized external pointer

// fields since lazily-initialized field will initially contain

// kNullExternalPointerHandle, which is guaranteed to result in kNullAddress

// being returned from the external pointer table.

template <ExternalPointerTagRange tag_range>

V8_INLINE Address ReadExternalPointerField(Address field_address,

IsolateForSandbox isolate);

// If the sandbox is enabled: reads the ExternalPointerHandle from the field and

// stores the external pointer to the corresponding entry in the external

// pointer table. If the sandbox is disabled: stores the external pointer to the

// field.

template <ExternalPointerTag tag>

V8_INLINE void WriteExternalPointerField(Address field_address,

IsolateForSandbox isolate,

Address value);

} // namespace internal

} // namespace v8

#endif // V8_SANDBOX_EXTERNAL_POINTER_H_