gecko-dev/ipc/mscom/DispatchForwarder.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/DispatchForwarder.h"

#include <oleauto.h>

#include <utility>

#include "mozilla/mscom/MainThreadInvoker.h"

namespace mozilla {
namespace mscom {

/* static */
HRESULT DispatchForwarder::Create(IInterceptor* aInterceptor,
                                  STAUniquePtr<IDispatch>& aTarget,
                                  IUnknown** aOutput) {
  MOZ_ASSERT(aInterceptor && aOutput);
  if (!aOutput) {
    return E_INVALIDARG;
  }
  *aOutput = nullptr;
  if (!aInterceptor) {
    return E_INVALIDARG;
  }
  DispatchForwarder* forwarder = new DispatchForwarder(aInterceptor, aTarget);
  HRESULT hr = forwarder->QueryInterface(IID_IDispatch, (void**)aOutput);
  forwarder->Release();
  return hr;
}

DispatchForwarder::DispatchForwarder(IInterceptor* aInterceptor,
                                     STAUniquePtr<IDispatch>& aTarget)
    : mRefCnt(1), mInterceptor(aInterceptor), mTarget(std::move(aTarget)) {}

DispatchForwarder::~DispatchForwarder() {}

HRESULT
DispatchForwarder::QueryInterface(REFIID riid, void** ppv) {
  if (!ppv) {
    return E_INVALIDARG;
  }

  // Since this class implements a tearoff, any interfaces that are not
  // IDispatch must be routed to the original object's QueryInterface.
  // This is especially important for IUnknown since COM uses that interface
  // to determine object identity.
  if (riid != IID_IDispatch) {
    return mInterceptor->QueryInterface(riid, ppv);
  }

  IUnknown* punk = static_cast<IDispatch*>(this);
  *ppv = punk;
  if (!punk) {
    return E_NOINTERFACE;
  }

  punk->AddRef();
  return S_OK;
}

ULONG
DispatchForwarder::AddRef() {
  return (ULONG)InterlockedIncrement((LONG*)&mRefCnt);
}

ULONG
DispatchForwarder::Release() {
  ULONG newRefCnt = (ULONG)InterlockedDecrement((LONG*)&mRefCnt);
  if (newRefCnt == 0) {
    delete this;
  }
  return newRefCnt;
}

HRESULT
DispatchForwarder::GetTypeInfoCount(UINT* pctinfo) {
  if (!pctinfo) {
    return E_INVALIDARG;
  }
  *pctinfo = 1;
  return S_OK;
}

HRESULT
DispatchForwarder::GetTypeInfo(UINT iTInfo, LCID lcid, ITypeInfo** ppTInfo) {
  // ITypeInfo as implemented by COM is apartment-neutral, so we don't need
  // to wrap it (yay!)
  if (mTypeInfo) {
    RefPtr<ITypeInfo> copy(mTypeInfo);
    copy.forget(ppTInfo);
    return S_OK;
  }
  HRESULT hr = E_UNEXPECTED;
  auto fn = [&]() -> void { hr = mTarget->GetTypeInfo(iTInfo, lcid, ppTInfo); };
  MainThreadInvoker invoker;
  if (!invoker.Invoke(
          NS_NewRunnableFunction("DispatchForwarder::GetTypeInfo", fn))) {
    return E_UNEXPECTED;
  }
  if (FAILED(hr)) {
    return hr;
  }
  mTypeInfo = *ppTInfo;
  return hr;
}

HRESULT
DispatchForwarder::GetIDsOfNames(REFIID riid, LPOLESTR* rgszNames, UINT cNames,
                                 LCID lcid, DISPID* rgDispId) {
  HRESULT hr = E_UNEXPECTED;
  auto fn = [&]() -> void {
    hr = mTarget->GetIDsOfNames(riid, rgszNames, cNames, lcid, rgDispId);
  };
  MainThreadInvoker invoker;
  if (!invoker.Invoke(
          NS_NewRunnableFunction("DispatchForwarder::GetIDsOfNames", fn))) {
    return E_UNEXPECTED;
  }
  return hr;
}

HRESULT
DispatchForwarder::Invoke(DISPID dispIdMember, REFIID riid, LCID lcid,
                          WORD wFlags, DISPPARAMS* pDispParams,
                          VARIANT* pVarResult, EXCEPINFO* pExcepInfo,
                          UINT* puArgErr) {
  HRESULT hr;
  if (!mInterface) {
    if (!mTypeInfo) {
      return E_UNEXPECTED;
    }
    TYPEATTR* typeAttr = nullptr;
    hr = mTypeInfo->GetTypeAttr(&typeAttr);
    if (FAILED(hr)) {
      return hr;
    }
    hr = mInterceptor->QueryInterface(typeAttr->guid,
                                      (void**)getter_AddRefs(mInterface));
    mTypeInfo->ReleaseTypeAttr(typeAttr);
    if (FAILED(hr)) {
      return hr;
    }
  }
  // We don't invoke IDispatch on the target, but rather on the interceptor!
  hr = ::DispInvoke(mInterface.get(), mTypeInfo, dispIdMember, wFlags,
                    pDispParams, pVarResult, pExcepInfo, puArgErr);
  return hr;
}

}  // namespace mscom
}  // namespace mozilla