#include <sys/mman.h>
#include <dlfcn.h>
#include <errno.h>
#include <stdio.h>
#include <stdint.h>

int main()
{
  void *addr = mmap(NULL, 65536, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  printf("mapped at %p\n", addr);
  void *addr2 = mmap(addr, 65536, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED | MAP_EXCL, -1, 0);
  if (addr2 == MAP_FAILED) {
    if (errno == ENOMEM) {
      printf("Successfully detected clash with ENOMEM\n");
    } else {
      perror("Unexpected error from mmap");
    }
  } else if (addr2 == addr) {
    printf("Error: unexpected overlapping mmap\n");
  } else {
    printf("Error: unexpected disjoint mmap\n");
  }

  addr = (void *)(~65535 & (uintptr_t)&main);
  printf("main at %p\n", addr);
  addr2 = mmap(addr, 65536, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED | MAP_EXCL, -1, 0);
  if (addr2 == MAP_FAILED) {
    if (errno == ENOMEM) {
      printf("Successfully detected clash with ENOMEM\n");
    } else {
      perror("Unexpected error from mmap");
    }
  } else if (addr2 == addr) {
    printf("Error: unexpected overlapping mmap\n");
  } else {
    printf("Error: unexpected disjoint mmap\n");
  }

  addr = (void *)(~65535 & (uintptr_t)dlsym(RTLD_DEFAULT, "printf"));
  printf("printf at %p\n", addr);
  addr2 = mmap(addr, 65536, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED | MAP_EXCL, -1, 0);
  if (addr2 == MAP_FAILED) {
    if (errno == ENOMEM) {
      printf("Successfully detected clash with ENOMEM\n");
    } else {
      perror("Unexpected error from mmap");
    }
  } else if (addr2 == addr) {
    printf("Error: unexpected overlapping mmap\n");
  } else {
    printf("Error: unexpected disjoint mmap\n");
  }

  return 0;
}