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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef dom_ipc_MemMapSnapshot_h
#define dom_ipc_MemMapSnapshot_h
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include "mozilla/RangedPtr.h"
#include "mozilla/Result.h"
#include "base/shared_memory.h"
#include "ErrorList.h"
namespace mozilla {
namespace loader {
class AutoMemMap;
}
namespace ipc {
/**
* A helper class for creating a read-only snapshot of memory-mapped data.
*
* The Init() method initializes a read-write memory mapped region of the given
* size, which can be initialized with arbitrary data. The Finalize() method
* remaps that region as read-only (and backs it with a read-only file
* descriptor), and initializes an AutoMemMap with the new contents.
*
* The file descriptor for the resulting AutoMemMap can be shared among
* processes, to safely access a shared, read-only copy of the data snapshot.
*/
class MOZ_RAII MemMapSnapshot {
public:
Result<Ok, nsresult> Init(size_t aSize);
Result<Ok, nsresult> Finalize(loader::AutoMemMap& aMap);
template <typename T>
RangedPtr<T> Get() {
MOZ_ASSERT(mInitialized);
return {static_cast<T*>(mMem.memory()), mMem.max_size() / sizeof(T)};
}
private:
base::SharedMemory mMem;
bool mInitialized = false;
};
} // namespace ipc
} // namespace mozilla
#endif // dom_ipc_MemMapSnapshot_h