call function in unrelated executable linux

If I have a pointer to a function and I give that to another (Unrelated/Child) Executable, how can I call that function without making a segfault?

At the moment I can create a function and assign it this memory adress:

Dim As Function (ByRef As String) As Integer MyFunction
' get pointer...
MyFunction = FunctionPointer

But then calling MyFunction I get a segfault (Obviously because the function I am calling is in another e开发者_Python百科xecutables adress space whitch I am not allowed to access)

How can I fix this/Work around it?

If you have control over the other executable (the one you want to call a function from), then build it as a PIE (position-independent executable), and load it into the first executable's address space.

In C, you would build with -fPIC -pie, then use dlopen(3) and dlsym(3).

In BASIC, I have no clue ;-(

It's not so much that you're "not allowed to access" the address space of the other function, but rather that that space is a totally different and unrelated address space. Each process has its own virtual address space, so the numeric value of your pointer has no meaning inside another functions address space, even if you were able to exchange it somehow.

For general inter-process communication you usually request shared memory explicitly from the system, but I'm not sure if FreeBasic exposes such functionality. Why not look up some existing remote procedure call libraries?