Function pointer example from the 'Towards Safe Enclaves' paper

towards-safe-enclaves-function-pointer-example.c

/*
  Neline van Ginkel, Raoul Strackx, Jan Tobias Mühlberg, Frank Piessens
  "Towards safe enclaves."
  4th Workshop on Hot Issues in Security Principles and Trust (HotSpot 2016).
  2016.
*/

#include <stdio.h>
#include <stdlib.h>

int count = 0;
void (*obs)(int);

void set_observer(void o(int)) {
  obs = o;
}

void inc() {
  count = count + 1;
  obs(count);
}

int getcount() {
  return count;
}

void printMe(int i) {
  printf("%d\n", i);
}


int main(void) {
  void (*fun_ptr)(int) = printMe;
  set_observer(fun_ptr);
  inc();
  return 0;
}