1 files changed, 223 insertions, 0 deletions
diff --git a/ipc/mscom/AgileReference.cpp b/ipc/mscom/AgileReference.cpp
new file mode 100644
index 0000000000..7a1b94822d
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+++ b/ipc/mscom/AgileReference.cpp
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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
+ * 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