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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_MEMORY_SHARED_MEMORY_MAPPER_H_
#define BASE_MEMORY_SHARED_MEMORY_MAPPER_H_
#include <stdint.h>
#include <optional>
#include "base/base_export.h"
#include "base/containers/span.h"
#include "base/memory/platform_shared_memory_handle.h"
namespace base {
// Interface to implement mapping and unmapping of shared memory regions into
// the virtual address space. The default implementation,
// |PlatformSharedMemoryMapper| uses the platform-specific APIs to map the
// region anywhere in the address space. Other implementations can be used for
// example to always map the regions into an existing address space reservation.
// Implementations of this interface should generally be statically allocated
// as SharedMemoryMappings keep a reference to their mapper.
class BASE_EXPORT SharedMemoryMapper {
public:
// Returns the default shared memory mapper.
static SharedMemoryMapper* GetDefaultInstance();
// Maps the shared memory region identified through the provided platform
// handle into the caller's address space.
virtual std::optional<span<uint8_t>> Map(
subtle::PlatformSharedMemoryHandle handle,
bool write_allowed,
uint64_t offset,
size_t size) = 0;
// Unmaps the specified region of shared memory from the caller's address
// space.
virtual void Unmap(span<uint8_t> mapping) = 0;
};
} // namespace base
#endif // BASE_MEMORY_SHARED_MEMORY_MAPPER_H_
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