How should I manage my memory in cpp with calling a C-style interface?

I want to manage pointer with smart pointer in my code, however I must call old C-style interface to get pointer, like that:

void getPointer(T** pT, int* pSize);

Users pass an empty pointer of Pt and return a pointer, I want to manage it with smart pointer in my code like

std::shared_ptr<T> ptr;

How should I write my code? I have been told that use get() method is not a safe idea. Another question is, how should I safely copy memory stored in smart pointer to a raw pointer? (or vice)