SIGSEGV handler using Python with C extension modules

Question

I'm trying to setup a SIGSEGV signal handler for Python using a C extension module:

import my_extension_module
import ctypes

my_extension_module.setup_segfault_handler()
ctypes.string_at(0) # i would like this to error and not segfault

I've seen several questions like this one and functions like longjmp or setjmp, but none of these seem to work how I intend.

I am aware that not terminating after a SIGSEGV is a bad idea for a number of reasons, but I need it nonetheless.

Here is my current code:

static jmp_buf buf;

void handle(int signum) {
  PyErr_SetString(PyExc_RuntimeError, "segmentation fault occured");
  longjmp(buf, 1);
}

static PyObject* method_setup() {
  signal(SIGSEGV, handle);
  setjmp(buf);

  Py_RETURN_NONE;
}