#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <xenctrl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/wait.h>

int main(int argc, char** argv)
{
  void* map_shr;
  void* map_tab;
  int ret;
  int status;
  int s_to_c[2];
  int c_to_s[2];

  /* setup pipes for communication */

  if(pipe(s_to_c) == -1)
    {
      perror("pipe");
      exit(EXIT_FAILURE);
    }
  if(pipe(c_to_s) == -1)
    {
      perror("pipe");
      exit(EXIT_FAILURE);
    }

  if (fork() != 0)  /* Parent code*/
    {
      uint32_t ref;
      char buf[1];
      xc_gntshr *shr_h = xc_gntshr_open(NULL, 0);

      printf("I'm server, with pid %d\n", getpid());

      if (shr_h == NULL)
        {
          perror("xc_gntshr_open");
          exit(EXIT_FAILURE);
        }

      map_shr = xc_gntshr_share_pages(shr_h, 0, 1, &ref, 1);
      if (map_shr == NULL)
        {
          perror("xc_gntshr_share_pages");
          exit(EXIT_FAILURE);
        }

      /* Send the gntref to the client. */
      write(s_to_c[1], &ref, sizeof(uint32_t));

      read(c_to_s[0], buf, 1);
      /* Now we unshare the page */
      ret = xc_gntshr_munmap(shr_h, map_shr, 1);
      if (ret != 0)
        {
          perror("xc_gntshr_munmap");
          exit(EXIT_FAILURE);
        }

      /* At this point, the kernel should complain… */
      /* Waiting for the child to die. */
      wait(&status);
      printf("Children died with status %d\n", status);
      return 0;
    }
  else /* Child code */
    {
      uint32_t ref;
      xc_gnttab *tab_h = xc_gnttab_open(NULL, 0);

      printf("I'm client, with pid %d\n", getpid());

      if (tab_h == NULL)
        {
          perror("xc_gnttab_open");
          exit(EXIT_FAILURE);
        }

      /* Receive the ref from the server. */
      read(s_to_c[0], &ref, sizeof(uint32_t));

      /* Ready to map! */

      map_tab = xc_gnttab_map_grant_ref(tab_h, 0, ref, PROT_READ|PROT_WRITE);
      if (map_tab == NULL)
        {
          perror("xc_gnttab_map_grant_ref");
          exit(EXIT_FAILURE);
        }

      /* Sending a msg to server to indicate that he can now
         unshare. */
      write(c_to_s[1], "\0", 1);

      return 0;
    }

  return 0;
}