CharStringToWCharString

SIZE_T CharStringToWCharString(_Inout_ PWCHAR Destination, _In_ PCHAR Source, SIZE_T _In_ MaximumAllowed)
{
	INT Length = (INT)MaximumAllowed;

	while (--Length >= 0)
	{
		if (!(*Destination++ = *Source++))
			return MaximumAllowed - Length - 1;
	}

	return MaximumAllowed - Length;
}