ipc/mscom/Interceptor.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_mscom_Interceptor_h
   8 #define mozilla_mscom_Interceptor_h
   9
  10 #include "mozilla/Move.h"
  11 #include "mozilla/Mutex.h"
  12 #include "nsTArray.h"
  13 #include "mozilla/mscom/IHandlerProvider.h"
  14 #include "mozilla/mscom/Ptr.h"
  15 #include "mozilla/mscom/WeakRef.h"
  16 #include "mozilla/RefPtr.h"
  17
  18 #include <objidl.h>
  19 #include <callobj.h>
  20
  21 namespace mozilla {
  22 namespace mscom {
  23 namespace detail {
  24
  25 class LiveSetAutoLock;
  26
  27 }  // namespace detail
  28
  29 // {8831EB53-A937-42BC-9921-B3E1121FDF86}
  30 DEFINE_GUID(IID_IInterceptorSink, 0x8831eb53, 0xa937, 0x42bc, 0x99, 0x21, 0xb3,
  31             0xe1, 0x12, 0x1f, 0xdf, 0x86);
  32
  33 struct IInterceptorSink : public ICallFrameEvents, public HandlerProvider {
  34   virtual STDMETHODIMP SetInterceptor(IWeakReference* aInterceptor) = 0;
  35 };
  36
  37 // {3710799B-ECA2-4165-B9B0-3FA1E4A9B230}
  38 DEFINE_GUID(IID_IInterceptor, 0x3710799b, 0xeca2, 0x4165, 0xb9, 0xb0, 0x3f,
  39             0xa1, 0xe4, 0xa9, 0xb2, 0x30);
  40
  41 struct IInterceptor : public IUnknown {
  42   virtual STDMETHODIMP GetTargetForIID(
  43       REFIID aIid, InterceptorTargetPtr<IUnknown>& aTarget) = 0;
  44   virtual STDMETHODIMP GetInterceptorForIID(REFIID aIid,
  45                                             void** aOutInterceptor) = 0;
  46 };
  47
  48 /**
  49  * The COM interceptor is the core functionality in mscom that allows us to
  50  * redirect method calls to different threads. It emulates the vtable of a
  51  * target interface. When a call is made on this emulated vtable, the call is
  52  * packaged up into an instance of the ICallFrame interface which may be passed
  53  * to other contexts for execution.
  54  *
  55  * In order to accomplish this, COM itself provides the CoGetInterceptor
  56  * function, which instantiates an ICallInterceptor. Note, however, that
  57  * ICallInterceptor only works on a single interface; we need to be able to
  58  * interpose QueryInterface calls so that we can instantiate a new
  59  * ICallInterceptor for each new interface that is requested.
  60  *
  61  * We accomplish this by using COM aggregation, which means that the
  62  * ICallInterceptor delegates its IUnknown implementation to its outer object
  63  * (the mscom::Interceptor we implement and control).
  64  */
  65 class Interceptor final : public WeakReferenceSupport,
  66                           public IStdMarshalInfo,
  67                           public IMarshal,
  68                           public IInterceptor {
  69  public:
  70   static HRESULT Create(STAUniquePtr<IUnknown> aTarget, IInterceptorSink* aSink,
  71                         REFIID aInitialIid, void** aOutInterface);
  72
  73   /**
  74    * Disconnect all remote clients for a given target.
  75    * Because Interceptors disable COM garbage collection to improve
  76    * performance, they never receive Release calls from remote clients. If
  77    * the object can be shut down while clients still hold a reference, this
  78    * function can be used to force COM to disconnect all remote connections
  79    * (using CoDisconnectObject) and thus release the associated references to
  80    * the Interceptor, its target and any objects associated with the
  81    * HandlerProvider.
  82    * Note that the specified target must be the same IUnknown pointer used to
  83    * create the Interceptor. Where there is multiple inheritance, querying for
  84    * IID_IUnknown and calling this function with that pointer alone will not
  85    * disconnect remotes for all interfaces. If you expect that the same object
  86    * may be fetched with different initial interfaces, you should call this
  87    * function once for each possible IUnknown pointer.
  88    * @return S_OK if there was an Interceptor for the given target,
  89    *         S_FALSE if there was not.
  90    */
  91   static HRESULT DisconnectRemotesForTarget(IUnknown* aTarget);
  92
  93   // IUnknown
  94   STDMETHODIMP QueryInterface(REFIID riid, void** ppv) override;
  95   STDMETHODIMP_(ULONG) AddRef() override;
  96   STDMETHODIMP_(ULONG) Release() override;
  97
  98   // IStdMarshalInfo
  99   STDMETHODIMP GetClassForHandler(DWORD aDestContext, void* aDestContextPtr,
 100                                   CLSID* aHandlerClsid) override;
 101
 102   // IMarshal
 103   STDMETHODIMP GetUnmarshalClass(REFIID riid, void* pv, DWORD dwDestContext,
 104                                  void* pvDestContext, DWORD mshlflags,
 105                                  CLSID* pCid) override;
 106   STDMETHODIMP GetMarshalSizeMax(REFIID riid, void* pv, DWORD dwDestContext,
 107                                  void* pvDestContext, DWORD mshlflags,
 108                                  DWORD* pSize) override;
 109   STDMETHODIMP MarshalInterface(IStream* pStm, REFIID riid, void* pv,
 110                                 DWORD dwDestContext, void* pvDestContext,
 111                                 DWORD mshlflags) override;
 112   STDMETHODIMP UnmarshalInterface(IStream* pStm, REFIID riid,
 113                                   void** ppv) override;
 114   STDMETHODIMP ReleaseMarshalData(IStream* pStm) override;
 115   STDMETHODIMP DisconnectObject(DWORD dwReserved) override;
 116
 117   // IInterceptor
 118   STDMETHODIMP GetTargetForIID(
 119       REFIID aIid, InterceptorTargetPtr<IUnknown>& aTarget) override;
 120   STDMETHODIMP GetInterceptorForIID(REFIID aIid,
 121                                     void** aOutInterceptor) override;
 122
 123  private:
 124   struct MapEntry {
 125     MapEntry(REFIID aIid, IUnknown* aInterceptor, IUnknown* aTargetInterface)
 126         : mIID(aIid),
 127           mInterceptor(aInterceptor),
 128           mTargetInterface(aTargetInterface) {}
 129
 130     IID mIID;
 131     RefPtr<IUnknown> mInterceptor;
 132     IUnknown* mTargetInterface;
 133   };
 134
 135  private:
 136   explicit Interceptor(IInterceptorSink* aSink);
 137   ~Interceptor();
 138   HRESULT GetInitialInterceptorForIID(detail::LiveSetAutoLock& aLiveSetLock,
 139                                       REFIID aTargetIid,
 140                                       STAUniquePtr<IUnknown> aTarget,
 141                                       void** aOutInterface);
 142   HRESULT GetInterceptorForIID(REFIID aIid, void** aOutInterceptor,
 143                                MutexAutoLock* aAlreadyLocked);
 144   MapEntry* Lookup(REFIID aIid);
 145   HRESULT QueryInterfaceTarget(REFIID aIid, void** aOutput,
 146                                TimeDuration* aOutDuration = nullptr);
 147   HRESULT WeakRefQueryInterface(REFIID aIid, IUnknown** aOutInterface) override;
 148   HRESULT CreateInterceptor(REFIID aIid, IUnknown* aOuter, IUnknown** aOutput);
 149   REFIID MarshalAs(REFIID aIid) const;
 150   HRESULT PublishTarget(detail::LiveSetAutoLock& aLiveSetLock,
 151                         RefPtr<IUnknown> aInterceptor, REFIID aTargetIid,
 152                         STAUniquePtr<IUnknown> aTarget);
 153
 154  private:
 155   InterceptorTargetPtr<IUnknown> mTarget;
 156   RefPtr<IInterceptorSink> mEventSink;
 157   mozilla::Mutex mInterceptorMapMutex;  // Guards mInterceptorMap
 158   // Using a nsTArray since the # of interfaces is not going to be very high
 159   nsTArray<MapEntry> mInterceptorMap;
 160   mozilla::Mutex mStdMarshalMutex;  // Guards mStdMarshalUnk and mStdMarshal
 161   RefPtr<IUnknown> mStdMarshalUnk;
 162   IMarshal* mStdMarshal;  // WEAK
 163   static MOZ_THREAD_LOCAL(bool) tlsCreatingStdMarshal;
 164 };
 165
 166 template <typename InterfaceT>
 167 inline HRESULT CreateInterceptor(STAUniquePtr<InterfaceT> aTargetInterface,
 168                                  IInterceptorSink* aEventSink,
 169                                  InterfaceT** aOutInterface) {
 170   if (!aTargetInterface || !aEventSink) {
 171     return E_INVALIDARG;
 172   }
 173
 174   REFIID iidTarget = __uuidof(InterfaceT);
 175
 176   STAUniquePtr<IUnknown> targetUnknown(aTargetInterface.release());
 177   return Interceptor::Create(std::move(targetUnknown), aEventSink, iidTarget,
 178                              (void**)aOutInterface);
 179 }
 180
 181 }  // namespace mscom
 182 }  // namespace mozilla
 183
 184 #endif  // mozilla_mscom_Interceptor_h