如何获取受管System.IO.FileStream的基础stdio FILE *？

I'm writing a .NET adaptor for a C/C++ library where a method "bar" takes a regular stdio FILE*. Is it possible to build an interface so that managed code user can pass a managed (File)Stream? That is without creating an intermediary buffer and code to pipe the data between. Also does the assumption that bar() reads only make things any better?I'm writing a .NET adaptor for a C/C++ library