msi: Add proper parameter handling to OLE automation interfaces.

[Robert Shearman]

Misha Koshelev wrote:
> +/* Macros for variant conversions */
> +#define V_DECLARE \
> +    VARIANTARG vararg[pDispParams->cArgs]; \
> +    int iVarCount; \
> +    HRESULT hr = S_OK; \
> +    memset(vararg, 0, sizeof(vararg));
> +#define V_PREPARE(n, type) \
> +    VariantInit(&vararg[n]); \
> +    hr = VariantChangeTypeEx(&vararg[n], &pDispParams->rgvarg[n], lcid, 0, VT_##type); \
> +    if (FAILED(hr)) \
> +    { \
> +        *puArgErr = n; \
> +        goto v_finish; \
> +    }
> +#define V_PREPAREOPT(n, type) \
> +    VariantInit(&vararg[n]); \
> +    if (FAILED(VariantChangeTypeEx(&vararg[n], &pDispParams->rgvarg[n], lcid, 0, VT_##type))) \
> +        VariantClear(&vararg[n]); 
> +#define V_PREPARED(n) (V_VT(&vararg[n]) != VT_EMPTY)
> +#define V(n, type) V_##type(&vararg[n])
> +#define V_RETURN(value, type) \
> +    V_VT(pVarResult) = VT_##type; \
> +    V_##type(pVarResult) = value;  
> +#define V_FAIL hr = E_FAIL; 
> +#define V_DEFAULT \
> +    default: \
> +        hr = DISP_E_MEMBERNOTFOUND;
> +#define V_FINISH \
> +    goto v_finish; /* suppress warnings about unused label v_free */ \
> +v_finish: \
> +    for (iVarCount = 0; iVarCount < pDispParams->cArgs; iVarCount++) \
> +        if (V_PREPARED(iVarCount))                                   \
> +            VariantClear(&vararg[iVarCount]); \
> +    return hr;
>   

This is quite ugly. You can at replace at least some of this with calls 
to DispGetParam.

A lot of the methods only have one parameter so will end up simpler 
without using these macros.

-- 
Rob Shearman