#define _XOPEN_SOURCE 600
#include <sys/mman.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char** argv)
{
  int pagesize = getpagesize();
  unsigned char* addr = NULL;
  posix_memalign((void**)&addr, pagesize, pagesize);
  mprotect(addr, pagesize, PROT_WRITE | PROT_READ | PROT_EXEC);
  addr[0] = 0x8b; addr[1] = 0x44; addr[2] = 0x24; addr[3] = 0x04; /* mov    0x4(%esp),%eax */
  addr[4] = 0x83; addr[5] = 0xc0; addr[6] = 0x01; /* add    $0x1,%eax */
  addr[7] = 0xc3; /* ret */
  
  printf("10+1=%d\n", ((int (*)(int))addr)(10));
  free(addr);
  return 0;
}