gecko-dev/ipc/mscom/ProxyStream.h

/* -*- 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
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_mscom_ProxyStream_h
#define mozilla_mscom_ProxyStream_h

#include "ipc/IPCMessageUtils.h"

#include "mozilla/mscom/Ptr.h"
#include "mozilla/RefPtr.h"
#include "mozilla/TypedEnumBits.h"
#include "mozilla/UniquePtr.h"

namespace mozilla {
namespace mscom {

enum class ProxyStreamFlags : uint32_t {
  eDefault = 0,
  // When ePreservable is set on a ProxyStream, its caller *must* call
  // GetPreservableStream() before the ProxyStream is destroyed.
  ePreservable = 1
};

MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(ProxyStreamFlags);

class ProxyStream final {
 public:
  class MOZ_RAII Environment {
   public:
    virtual ~Environment() = default;
    virtual bool Push() = 0;
    virtual bool Pop() = 0;
  };

  class MOZ_RAII DefaultEnvironment : public Environment {
   public:
    bool Push() override { return true; }
    bool Pop() override { return true; }
  };

  ProxyStream();
  ProxyStream(REFIID aIID, IUnknown* aObject, Environment* aEnv,
              ProxyStreamFlags aFlags = ProxyStreamFlags::eDefault);
  ProxyStream(REFIID aIID, const BYTE* aInitBuf, const int aInitBufSize,
              Environment* aEnv);

  ~ProxyStream();

  // Not copyable because this would mess up the COM marshaling.
  ProxyStream(const ProxyStream& aOther) = delete;
  ProxyStream& operator=(const ProxyStream& aOther) = delete;

  ProxyStream(ProxyStream&& aOther);
  ProxyStream& operator=(ProxyStream&& aOther);

  inline bool IsValid() const { return !(mUnmarshaledProxy && mStream); }

  bool GetInterface(void** aOutInterface);
  const BYTE* GetBuffer(int& aReturnedBufSize) const;

  PreservedStreamPtr GetPreservedStream();

  bool operator==(const ProxyStream& aOther) const { return this == &aOther; }

 private:
  RefPtr<IStream> mStream;
  BYTE* mGlobalLockedBuf;
  HGLOBAL mHGlobal;
  int mBufSize;
  ProxyUniquePtr<IUnknown> mUnmarshaledProxy;
  bool mPreserveStream;
};

namespace detail {

template <typename Interface>
struct EnvironmentSelector {
  typedef ProxyStream::DefaultEnvironment Type;
};

}  // namespace detail
}  // namespace mscom
}  // namespace mozilla

#endif  // mozilla_mscom_ProxyStream_h