// simply check if a COM object supports a particular COM interface
// (without doing any casting by the CLR, which does much more than this under the covers)
public static bool DoesComObjPtrSupportInterface <T>(IntPtr comObjPtr)
{
var iid = typeof(T).GUID;
var hr = RdMarshal.QueryInterface(comObjPtr, ref iid, out var outInterfacePtr);
if (!ComHelper.HRESULT_FAILED(hr))
{
RdMarshal.Release(outInterfacePtr);
return(true);
}
return(false);
}
private void TraceRelease(int rcwCount, ref bool addRef)
{
if (!addRef)
{
// Temporarily add a ref so that we can safely call IUnknown::Release
// to report the ref count in the log.
RdMarshal.AddRef(_pUnk);
}
var refCount = RdMarshal.Release(_pUnk);
Debug.Print($"ComPointer:: Disposed: _pUnk: {RdMarshal.FormatPtr(_pUnk)} _interface: {typeof(TComInterface).Name} - {Interface.GetHashCode()} addRef: {_addRef} rcwCount: {rcwCount} refCount: {refCount}");
addRef = false;
}
private void ReleaseUnmanagedResources()
{
if (_disposed)
{
return;
}
var rcwCount = RdMarshal.ReleaseComObject(Interface);
var addRef = _addRef;
TraceRelease(rcwCount, ref addRef);
if (addRef)
{
RdMarshal.Release(_pUnk);
}
_disposed = true;
}
void ComTypes.ITypeInfo.CreateInstance(object pUnkOuter, ref Guid riid, out object ppvObj)
{
// initialize out parameters
ppvObj = default;
using (var outPpvObj = AddressableVariables.CreateObjectPtr <object>())
{
var unkOuter = RdMarshal.GetIUnknownForObject(pUnkOuter);
var hr = _this_Internal.CreateInstance(unkOuter, riid, outPpvObj.Address);
RdMarshal.Release(unkOuter);
if (ComHelper.HRESULT_FAILED(hr))
{
HandleBadHRESULT(hr);
}
ppvObj = outPpvObj.Value;
}
}
/// <summary>
/// Takes a COM object, and reads the unmanaged memory given by its pointer, allowing us to read internal fields
/// </summary>
/// <typeparam name="T">the type of structure to return</typeparam>
/// <param name="comObj">the COM object</param>
/// <returns>the requested structure T</returns>
public static T ReadComObjectStructure <T>(object comObj)
{
// Reads a COM object as a structure to copy its internal fields
if (!RdMarshal.IsComObject(comObj))
{
throw new ArgumentException("Expected a COM object");
}
var referencesPtr = RdMarshal.GetIUnknownForObjectInContext(comObj);
if (referencesPtr == IntPtr.Zero)
{
throw new InvalidOperationException("Cannot access the TypeLib API from this thread. TypeLib API must be accessed from the main thread.");
}
var retVal = ReadStructureSafe <T>(referencesPtr);
RdMarshal.Release(referencesPtr);
return(retVal);
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="outerObject">The object that needs interface requests filtered</param>
/// <param name="queryForType">determines whether we call QueryInterface for the interface or not</param>
/// <remarks>if the passed in outerObject is known to point to the correct vtable for the interface, then queryForType can be false</remarks>
/// <returns>if outerObject is IntPtr.Zero, then a null wrapper, else an aggregated wrapper</returns>
public RestrictComInterfaceByAggregation(IntPtr outerObject, bool queryForType = true)
{
if (queryForType)
{
var iid = typeof(T).GUID;
if (ComHelper.HRESULT_FAILED(RdMarshal.QueryInterface(outerObject, ref iid, out _outerObject)))
{
// allow null wrapping here
return;
}
}
else
{
_outerObject = outerObject;
RdMarshal.AddRef(_outerObject);
}
var clrAggregator = RdMarshal.CreateAggregatedObject(_outerObject, this);
WrappedObject = (T)RdMarshal.GetObjectForIUnknown(clrAggregator); // when this CCW object gets released, it will free the aggObjInner (well, after GC)
RdMarshal.Release(clrAggregator); // _wrappedObject holds a reference to this now
}
protected virtual void Dispose(bool disposing)
{
if (_isDisposed || !disposing)
{
return;
}
_isDisposed = true;
if (WrappedObject != null)
{
RdMarshal.ReleaseComObject(WrappedObject);
}
if (_outerObject != IntPtr.Zero)
{
RdMarshal.Release(_outerObject);
// dont set _outerObject to IntPtr.Zero here, as GetInterface() can still be called by the outer RCW
// if it is still alive. For example, if ExtractWrappedObject was used and the outer object hasn't yet
// been released with ReleaseComObject. In that circumstance _outerObject will still be a valid pointer
// due to the internally held reference, and so GetInterface() calls past this point are still OK.
}
}
