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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/. */
#ifndef mozilla_mscom_Interceptor_h
#define mozilla_mscom_Interceptor_h
#include <callobj.h>
#include <objidl.h>
#include <utility>
#include "mozilla/Mutex.h"
#include "mozilla/RefPtr.h"
#include "mozilla/mscom/IHandlerProvider.h"
#include "mozilla/mscom/Ptr.h"
#include "mozilla/mscom/WeakRef.h"
#include "nsTArray.h"
namespace mozilla {
namespace mscom {
namespace detail {
class LiveSetAutoLock;
} // namespace detail
// {8831EB53-A937-42BC-9921-B3E1121FDF86}
DEFINE_GUID(IID_IInterceptorSink, 0x8831eb53, 0xa937, 0x42bc, 0x99, 0x21, 0xb3,
0xe1, 0x12, 0x1f, 0xdf, 0x86);
struct IInterceptorSink : public ICallFrameEvents, public HandlerProvider {
virtual STDMETHODIMP SetInterceptor(IWeakReference* aInterceptor) = 0;
};
// {3710799B-ECA2-4165-B9B0-3FA1E4A9B230}
DEFINE_GUID(IID_IInterceptor, 0x3710799b, 0xeca2, 0x4165, 0xb9, 0xb0, 0x3f,
0xa1, 0xe4, 0xa9, 0xb2, 0x30);
struct IInterceptor : public IUnknown {
virtual STDMETHODIMP GetTargetForIID(
REFIID aIid, InterceptorTargetPtr<IUnknown>& aTarget) = 0;
virtual STDMETHODIMP GetInterceptorForIID(REFIID aIid,
void** aOutInterceptor) = 0;
virtual STDMETHODIMP GetEventSink(IInterceptorSink** aSink) = 0;
};
/**
* The COM interceptor is the core functionality in mscom that allows us to
* redirect method calls to different threads. It emulates the vtable of a
* target interface. When a call is made on this emulated vtable, the call is
* packaged up into an instance of the ICallFrame interface which may be passed
* to other contexts for execution.
*
* In order to accomplish this, COM itself provides the CoGetInterceptor
* function, which instantiates an ICallInterceptor. Note, however, that
* ICallInterceptor only works on a single interface; we need to be able to
* interpose QueryInterface calls so that we can instantiate a new
* ICallInterceptor for each new interface that is requested.
*
* We accomplish this by using COM aggregation, which means that the
* ICallInterceptor delegates its IUnknown implementation to its outer object
* (the mscom::Interceptor we implement and control).
*
* ACHTUNG! mscom::Interceptor uses FastMarshaler to disable COM garbage
* collection. If you use this class, you *must* call
* Interceptor::DisconnectRemotesForTarget when an object is no longer relevant.
* Otherwise, the object will never be released, causing a leak.
*/
class Interceptor final : public WeakReferenceSupport,
public IStdMarshalInfo,
public IMarshal,
public IInterceptor {
public:
static HRESULT Create(STAUniquePtr<IUnknown> aTarget, IInterceptorSink* aSink,
REFIID aInitialIid, void** aOutInterface);
/**
* Disconnect all remote clients for a given target.
* Because Interceptors disable COM garbage collection to improve
* performance, they never receive Release calls from remote clients. If
* the object can be shut down while clients still hold a reference, this
* function can be used to force COM to disconnect all remote connections
* (using CoDisconnectObject) and thus release the associated references to
* the Interceptor, its target and any objects associated with the
* HandlerProvider.
* Note that the specified target must be the same IUnknown pointer used to
* create the Interceptor. Where there is multiple inheritance, querying for
* IID_IUnknown and calling this function with that pointer alone will not
* disconnect remotes for all interfaces. If you expect that the same object
* may be fetched with different initial interfaces, you should call this
* function once for each possible IUnknown pointer.
* @return S_OK if there was an Interceptor for the given target,
* S_FALSE if there was not.
*/
static HRESULT DisconnectRemotesForTarget(IUnknown* aTarget);
// IUnknown
STDMETHODIMP QueryInterface(REFIID riid, void** ppv) override;
STDMETHODIMP_(ULONG) AddRef() override;
STDMETHODIMP_(ULONG) Release() override;
// IStdMarshalInfo
STDMETHODIMP GetClassForHandler(DWORD aDestContext, void* aDestContextPtr,
CLSID* aHandlerClsid) override;
// IMarshal
STDMETHODIMP GetUnmarshalClass(REFIID riid, void* pv, DWORD dwDestContext,
void* pvDestContext, DWORD mshlflags,
CLSID* pCid) override;
STDMETHODIMP GetMarshalSizeMax(REFIID riid, void* pv, DWORD dwDestContext,
void* pvDestContext, DWORD mshlflags,
DWORD* pSize) override;
STDMETHODIMP MarshalInterface(IStream* pStm, REFIID riid, void* pv,
DWORD dwDestContext, void* pvDestContext,
DWORD mshlflags) override;
STDMETHODIMP UnmarshalInterface(IStream* pStm, REFIID riid,
void** ppv) override;
STDMETHODIMP ReleaseMarshalData(IStream* pStm) override;
STDMETHODIMP DisconnectObject(DWORD dwReserved) override;
// IInterceptor
STDMETHODIMP GetTargetForIID(
REFIID aIid, InterceptorTargetPtr<IUnknown>& aTarget) override;
STDMETHODIMP GetInterceptorForIID(REFIID aIid,
void** aOutInterceptor) override;
STDMETHODIMP GetEventSink(IInterceptorSink** aSink) override {
RefPtr<IInterceptorSink> sink = mEventSink;
sink.forget(aSink);
return mEventSink ? S_OK : S_FALSE;
}
private:
struct MapEntry {
MapEntry(REFIID aIid, IUnknown* aInterceptor, IUnknown* aTargetInterface)
: mIID(aIid),
mInterceptor(aInterceptor),
mTargetInterface(aTargetInterface) {}
IID mIID;
RefPtr<IUnknown> mInterceptor;
IUnknown* mTargetInterface;
};
private:
explicit Interceptor(IInterceptorSink* aSink);
~Interceptor();
HRESULT GetInitialInterceptorForIID(detail::LiveSetAutoLock& aLiveSetLock,
REFIID aTargetIid,
STAUniquePtr<IUnknown> aTarget,
void** aOutInterface);
HRESULT GetInterceptorForIID(REFIID aIid, void** aOutInterceptor,
MutexAutoLock* aAlreadyLocked);
MapEntry* Lookup(REFIID aIid);
HRESULT QueryInterfaceTarget(REFIID aIid, void** aOutput,
TimeDuration* aOutDuration = nullptr);
HRESULT WeakRefQueryInterface(REFIID aIid, IUnknown** aOutInterface) override;
HRESULT CreateInterceptor(REFIID aIid, IUnknown* aOuter, IUnknown** aOutput);
REFIID MarshalAs(REFIID aIid) const;
HRESULT PublishTarget(detail::LiveSetAutoLock& aLiveSetLock,
RefPtr<IUnknown> aInterceptor, REFIID aTargetIid,
STAUniquePtr<IUnknown> aTarget);
private:
InterceptorTargetPtr<IUnknown> mTarget;
RefPtr<IInterceptorSink> mEventSink;
mozilla::Mutex mInterceptorMapMutex; // Guards mInterceptorMap
// Using a nsTArray since the # of interfaces is not going to be very high
nsTArray<MapEntry> mInterceptorMap;
mozilla::Mutex mStdMarshalMutex; // Guards mStdMarshalUnk and mStdMarshal
RefPtr<IUnknown> mStdMarshalUnk;
IMarshal* mStdMarshal; // WEAK
static MOZ_THREAD_LOCAL(bool) tlsCreatingStdMarshal;
};
template <typename InterfaceT>
inline HRESULT CreateInterceptor(STAUniquePtr<InterfaceT> aTargetInterface,
IInterceptorSink* aEventSink,
InterfaceT** aOutInterface) {
if (!aTargetInterface || !aEventSink) {
return E_INVALIDARG;
}
REFIID iidTarget = __uuidof(InterfaceT);
STAUniquePtr<IUnknown> targetUnknown(aTargetInterface.release());
return Interceptor::Create(std::move(targetUnknown), aEventSink, iidTarget,
(void**)aOutInterface);
}
} // namespace mscom
} // namespace mozilla
#endif // mozilla_mscom_Interceptor_h
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