Is there a way to view COM entries by traversing a TLB file in .NET?

Question

I'm converting an application to use registration free COM. There are a few 3rd party COM dll's that would normally have regsvr32 called on them. I tested that I can create objects from these 3rd party dlls by making a side-by-side manifest.

I used the OLE/COM viewer built into Windows to get this information. However I would like to make a program that could do this for me manually, as these 3rd party libraries have lots of classes I need to put in the manifest.

Does anyone know of a way to programatically traverse a type library?

Answer 1

I took Hans' advice and used LoadTypeLib.

For anyone looking for example code, this should be a great starting point. I wrote it this morning and was able to get xml that I needed.

Forgive me for not releasing the objects! I don't have time to fully flesh out the rest of this answer right now. Edits are welcome.

    [DllImport("oleaut32.dll", PreserveSig = false)]
    public static extern ITypeLib LoadTypeLib([In, MarshalAs(UnmanagedType.LPWStr)] string typelib);

    public static void ParseTypeLib(string filePath)
    {

        string fileNameOnly = Path.GetFileNameWithoutExtension(filePath);
        ITypeLib typeLib = LoadTypeLib(filePath);

        int count = typeLib.GetTypeInfoCount();
        IntPtr ipLibAtt = IntPtr.Zero;
        typeLib.GetLibAttr(out ipLibAtt);

        var typeLibAttr = (System.Runtime.InteropServices.ComTypes.TYPELIBATTR)
            Marshal.PtrToStructure(ipLibAtt, typeof(System.Runtime.InteropServices.ComTypes.TYPELIBATTR));
        Guid tlbId = typeLibAttr.guid;

        for(int i=0; i< count; i++)
        {
            ITypeInfo typeInfo = null;
            typeLib.GetTypeInfo(i, out typeInfo);

            //figure out what guids, typekind, and names of the thing we're dealing with
            IntPtr ipTypeAttr = IntPtr.Zero;
            typeInfo.GetTypeAttr(out ipTypeAttr);

            //unmarshal the pointer into a structure into something we can read
            var typeattr = (System.Runtime.InteropServices.ComTypes.TYPEATTR)
                Marshal.PtrToStructure(ipTypeAttr, typeof(System.Runtime.InteropServices.ComTypes.TYPEATTR));

            System.Runtime.InteropServices.ComTypes.TYPEKIND typeKind = typeattr.typekind;
            Guid typeId = typeattr.guid;

            //get the name of the type
            string strName, strDocString, strHelpFile;
            int dwHelpContext;
            typeLib.GetDocumentation(i, out strName, out strDocString, out dwHelpContext, out strHelpFile);


            if (typeKind == System.Runtime.InteropServices.ComTypes.TYPEKIND.TKIND_COCLASS)
            {
                string xmlComClassFormat = "<comClass clsid=\"{0}\" tlbid=\"{1}\" description=\"{2}\" progid=\"{3}.{4}\"></comClass>";
                string comClassXml = String.Format(xmlComClassFormat, 
                    typeId.ToString("B").ToUpper(),
                    tlbId.ToString("B").ToUpper(),
                    strDocString,
                    fileNameOnly, strName
                    );
                //Debug.WriteLine(comClassXml);
            }
            else if(typeKind == System.Runtime.InteropServices.ComTypes.TYPEKIND.TKIND_INTERFACE)
            {
                string xmlProxyStubFormat = "<comInterfaceExternalProxyStub name=\"{0}\" iid=\"{1}\" tlbid=\"{2}\" proxyStubClsid32=\"{3}\"></comInterfaceExternalProxyStub>";
                string proxyStubXml = String.Format(xmlProxyStubFormat,
                    strName,
                    typeId.ToString("B").ToUpper(),
                    tlbId.ToString("B").ToUpper(),
                    "{00020424-0000-0000-C000-000000000046}"
                );
                //Debug.WriteLine(proxyStubXml);
            }

        }

        return;
    }
}