gecko-dev/ipc/mscom/AgileReference.cpp

/* -*- 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/. */

#include "mozilla/mscom/AgileReference.h"

#include <utility>

#include "mozilla/Assertions.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/DynamicallyLinkedFunctionPtr.h"
#include "mozilla/mscom/Utils.h"

#if defined(MOZILLA_INTERNAL_API)
#  include "nsDebug.h"
#  include "nsPrintfCString.h"
#endif  // defined(MOZILLA_INTERNAL_API)

#if NTDDI_VERSION < NTDDI_WINBLUE

// Declarations from Windows SDK specific to Windows 8.1

enum AgileReferenceOptions {
  AGILEREFERENCE_DEFAULT = 0,
  AGILEREFERENCE_DELAYEDMARSHAL = 1,
};

HRESULT WINAPI RoGetAgileReference(AgileReferenceOptions options, REFIID riid,
                                   IUnknown* pUnk,
                                   IAgileReference** ppAgileReference);

#endif  // NTDDI_VERSION < NTDDI_WINBLUE

namespace mozilla {
namespace mscom {
namespace detail {

GlobalInterfaceTableCookie::GlobalInterfaceTableCookie(IUnknown* aObject,
                                                       REFIID aIid,
                                                       HRESULT& aOutHResult)
    : mCookie(0) {
  IGlobalInterfaceTable* git = ObtainGit();
  MOZ_ASSERT(git);
  if (!git) {
    aOutHResult = E_POINTER;
    return;
  }

  aOutHResult = git->RegisterInterfaceInGlobal(aObject, aIid, &mCookie);
  MOZ_ASSERT(SUCCEEDED(aOutHResult));
}

GlobalInterfaceTableCookie::~GlobalInterfaceTableCookie() {
  IGlobalInterfaceTable* git = ObtainGit();
  MOZ_ASSERT(git);
  if (!git) {
    return;
  }

  DebugOnly<HRESULT> hr = git->RevokeInterfaceFromGlobal(mCookie);
#if defined(MOZILLA_INTERNAL_API)
  NS_WARNING_ASSERTION(
      SUCCEEDED(hr),
      nsPrintfCString("IGlobalInterfaceTable::RevokeInterfaceFromGlobal failed "
                      "with HRESULT 0x%08lX",
                      ((HRESULT)hr))
          .get());
#else
  MOZ_ASSERT(SUCCEEDED(hr));
#endif  // defined(MOZILLA_INTERNAL_API)
  mCookie = 0;
}

HRESULT GlobalInterfaceTableCookie::GetInterface(REFIID aIid,
                                                 void** aOutInterface) const {
  IGlobalInterfaceTable* git = ObtainGit();
  MOZ_ASSERT(git);
  if (!git) {
    return E_UNEXPECTED;
  }

  MOZ_ASSERT(IsValid());
  return git->GetInterfaceFromGlobal(mCookie, aIid, aOutInterface);
}

/* static */
IGlobalInterfaceTable* GlobalInterfaceTableCookie::ObtainGit() {
  // Internally to COM, the Global Interface Table is a singleton, therefore we
  // don't worry about holding onto this reference indefinitely.
  static IGlobalInterfaceTable* sGit = []() -> IGlobalInterfaceTable* {
    IGlobalInterfaceTable* result = nullptr;
    DebugOnly<HRESULT> hr = ::CoCreateInstance(
        CLSID_StdGlobalInterfaceTable, nullptr, CLSCTX_INPROC_SERVER,
        IID_IGlobalInterfaceTable, reinterpret_cast<void**>(&result));
    MOZ_ASSERT(SUCCEEDED(hr));
    return result;
  }();

  return sGit;
}

}  // namespace detail

AgileReference::AgileReference() : mIid(), mHResult(E_NOINTERFACE) {}

AgileReference::AgileReference(REFIID aIid, IUnknown* aObject)
    : mIid(aIid), mHResult(E_UNEXPECTED) {
  AssignInternal(aObject);
}

AgileReference::AgileReference(AgileReference&& aOther)
    : mIid(aOther.mIid),
      mAgileRef(std::move(aOther.mAgileRef)),
      mGitCookie(std::move(aOther.mGitCookie)),
      mHResult(aOther.mHResult) {
  aOther.mHResult = CO_E_RELEASED;
}

void AgileReference::Assign(REFIID aIid, IUnknown* aObject) {
  Clear();
  mIid = aIid;
  AssignInternal(aObject);
}

void AgileReference::AssignInternal(IUnknown* aObject) {
  // We expect mIid to already be set
  DebugOnly<IID> zeroIid = {};
  MOZ_ASSERT(mIid != zeroIid);

  /*
   * There are two possible techniques for creating agile references. Starting
   * with Windows 8.1, we may use the RoGetAgileReference API, which is faster.
   * If that API is not available, we fall back to using the Global Interface
   * Table.
   */
  static const StaticDynamicallyLinkedFunctionPtr<decltype(
      &::RoGetAgileReference)>
      pRoGetAgileReference(L"ole32.dll", "RoGetAgileReference");

  MOZ_ASSERT(aObject);

  if (pRoGetAgileReference &&
      SUCCEEDED(mHResult =
                    pRoGetAgileReference(AGILEREFERENCE_DEFAULT, mIid, aObject,
                                         getter_AddRefs(mAgileRef)))) {
    return;
  }

  mGitCookie = new detail::GlobalInterfaceTableCookie(aObject, mIid, mHResult);
  MOZ_ASSERT(mGitCookie->IsValid());
}

AgileReference::~AgileReference() { Clear(); }

void AgileReference::Clear() {
  mIid = {};
  mAgileRef = nullptr;
  mGitCookie = nullptr;
  mHResult = E_NOINTERFACE;
}

AgileReference& AgileReference::operator=(const AgileReference& aOther) {
  Clear();
  mIid = aOther.mIid;
  mAgileRef = aOther.mAgileRef;
  mGitCookie = aOther.mGitCookie;
  mHResult = aOther.mHResult;
  return *this;
}

AgileReference& AgileReference::operator=(AgileReference&& aOther) {
  Clear();
  mIid = aOther.mIid;
  mAgileRef = std::move(aOther.mAgileRef);
  mGitCookie = std::move(aOther.mGitCookie);
  mHResult = aOther.mHResult;
  aOther.mHResult = CO_E_RELEASED;
  return *this;
}

HRESULT
AgileReference::Resolve(REFIID aIid, void** aOutInterface) const {
  MOZ_ASSERT(aOutInterface);
  // This check is exclusive-OR; we should have one or the other, but not both
  MOZ_ASSERT((mAgileRef || mGitCookie) && !(mAgileRef && mGitCookie));
  MOZ_ASSERT(IsCOMInitializedOnCurrentThread());

  if (!aOutInterface) {
    return E_INVALIDARG;
  }

  *aOutInterface = nullptr;

  if (mAgileRef) {
    // IAgileReference lets you directly resolve the interface you want...
    return mAgileRef->Resolve(aIid, aOutInterface);
  }

  if (!mGitCookie) {
    return E_UNEXPECTED;
  }

  RefPtr<IUnknown> originalInterface;
  HRESULT hr =
      mGitCookie->GetInterface(mIid, getter_AddRefs(originalInterface));
  if (FAILED(hr)) {
    return hr;
  }

  if (aIid == mIid) {
    originalInterface.forget(aOutInterface);
    return S_OK;
  }

  // ...Whereas the GIT requires us to obtain the same interface that we
  // requested and then QI for the desired interface afterward.
  return originalInterface->QueryInterface(aIid, aOutInterface);
}

}  // namespace mscom
}  // namespace mozilla