WMI MI_ApplicationFT struct is hard to use

[riverar]

Related: microsoft/windows-rs#1572

WMI APIs such as MI_Application_NewSession are header-only. (Nearly all of them are.) That's not a problem per se but in this case, after calling MI_Application_InitializeV1 you get back a function table defined as such:

typedef struct _MI_ApplicationFT
{
    MI_Result (MI_CALL *Close)(
        _Inout_     MI_Application *application);

    MI_Result (MI_CALL *NewSession)(
        _In_     MI_Application *application,
        _In_opt_z_ const MI_Char *protocol,
        _In_opt_z_ const MI_Char *destination,
        _In_opt_ MI_DestinationOptions *options,
        _In_opt_ MI_SessionCallbacks *callbacks,
        _Outptr_opt_result_maybenull_ MI_Instance **extendedError,
        _Out_    MI_Session *session);

    MI_Result (MI_CALL *NewHostedProvider)(
        _In_     MI_Application *application,
        _In_z_     const MI_Char *namespaceName,
        _In_z_     const MI_Char *providerName,
        _In_     MI_MainFunction mi_Main,
        _Outptr_opt_result_maybenull_ MI_Instance **extendedError,
        _Out_    MI_HostedProvider *provider
        );

   // ...
}

Metadata currently houses a table of difficult to use bare IntPtrs.

public struct MI_ApplicationFT
{
	public IntPtr Close;
	public IntPtr NewSession;
	public IntPtr NewHostedProvider;
	public IntPtr NewInstance;
	public IntPtr NewDestinationOptions;
	public IntPtr NewOperationOptions;
	public IntPtr NewSubscriptionDeliveryOptions;
	public IntPtr NewSerializer;
	public IntPtr NewDeserializer;
	public IntPtr NewInstanceFromClass;
	public IntPtr NewClass;
}

[mikebattista]

What change would you like to see here?

[riverar]

@mikebattista I think parsing the typedef blob into a delegate would be ideal. Maybe we can short term do this manually?

[vpopescu]

Any further thoughts/decisions on this?

[mikebattista]

The scraped C# is below. Seems like yet another case of not honoring the NativeTypeName like #1006 and #983.

    public partial struct MI_ApplicationFT
    {
        [NativeTypeName("MI_Result (*)(MI_Application *) __attribute__((stdcall))")]
        public IntPtr Close;

        [NativeTypeName("MI_Result (*)(MI_Application *, const MI_Char *, const MI_Char *, MI_DestinationOptions *, MI_SessionCallbacks *, MI_Instance **, MI_Session *) __attribute__((stdcall))")]
        public IntPtr NewSession;

        [NativeTypeName("MI_Result (*)(MI_Application *, const MI_Char *, const MI_Char *, MI_MainFunction, MI_Instance **, MI_HostedProvider *) __attribute__((stdcall))")]
        public IntPtr NewHostedProvider;

        [NativeTypeName("MI_Result (*)(MI_Application *, const MI_Char *, const MI_ClassDecl *, MI_Instance **) __attribute__((stdcall))")]
        public IntPtr NewInstance;

        [NativeTypeName("MI_Result (*)(MI_Application *, MI_DestinationOptions *) __attribute__((stdcall))")]
        public IntPtr NewDestinationOptions;

        [NativeTypeName("MI_Result (*)(MI_Application *, MI_Boolean, MI_OperationOptions *) __attribute__((stdcall))")]
        public IntPtr NewOperationOptions;

        [NativeTypeName("MI_Result (*)(MI_Application *, MI_SubscriptionDeliveryType, MI_SubscriptionDeliveryOptions *) __attribute__((stdcall))")]
        public IntPtr NewSubscriptionDeliveryOptions;

        [NativeTypeName("MI_Result (*)(MI_Application *, MI_Uint32, MI_Char *, MI_Serializer *) __attribute__((stdcall))")]
        public IntPtr NewSerializer;

        [NativeTypeName("MI_Result (*)(MI_Application *, MI_Uint32, MI_Char *, MI_Deserializer *) __attribute__((stdcall))")]
        public IntPtr NewDeserializer;

        [NativeTypeName("MI_Result (*)(MI_Application *, const MI_Char *, const MI_Class *, MI_Instance **) __attribute__((stdcall))")]
        public IntPtr NewInstanceFromClass;

        [NativeTypeName("MI_Result (*)(MI_Application *, const MI_ClassDecl *, const MI_Char *, const MI_Char *, MI_Class **) __attribute__((stdcall))")]
        public IntPtr NewClass;
    }

[mikebattista]

Delegates will need to be manually defined as with #796 and #983.