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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MOJO_CORE_PLATFORM_SHARED_MEMORY_MAPPING_H_
#define MOJO_CORE_PLATFORM_SHARED_MEMORY_MAPPING_H_
#include <stddef.h>
#include <variant>
#include "base/memory/platform_shared_memory_region.h"
#include "base/memory/shared_memory_mapping.h"
#include "mojo/core/system_impl_export.h"
namespace mojo {
namespace core {
// A mapping of a |base::subtle::PlatformSharedMemoryRegion|, created
// exclusively by |SharedBufferDispatcher::MapBuffer()|. Automatically maps
// upon construction and unmaps upon destruction.
//
// Mappings are NOT thread-safe.
//
// This may represent either a |base::ReadOnlySharedMemoryMapping| OR a
// |base::WritableSharedMemoryMapping|, and it supports non-page-aligned base
// offsets for convenience.
class MOJO_SYSTEM_IMPL_EXPORT PlatformSharedMemoryMapping {
public:
PlatformSharedMemoryMapping(base::subtle::PlatformSharedMemoryRegion* region,
size_t offset,
size_t length);
PlatformSharedMemoryMapping(const PlatformSharedMemoryMapping&) = delete;
PlatformSharedMemoryMapping& operator=(const PlatformSharedMemoryMapping&) =
delete;
~PlatformSharedMemoryMapping();
bool IsValid() const;
void* GetBase() const;
size_t GetLength() const;
private:
std::variant<std::monostate,
base::ReadOnlySharedMemoryMapping,
base::WritableSharedMemoryMapping>
mapping_;
};
} // namespace core
} // namespace mojo
#endif // MOJO_CORE_PLATFORM_SHARED_MEMORY_MAPPING_H_
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