#include <sys/mman.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>

int main(int argc, char *argv[])
{
  char *addr;
  char *mfile = "lena.jpg"; 
  char infile[64];
  int fd01, fd02;
  pid_t pid;

  struct stat st;

  fd01 = open(mfile, O_RDWR);

  stat(mfile, &st); 

  addr = (char*)mmap(NULL, st.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd01, 0);

  pid = fork();

  if(pid == 0)
  {
    execlp("display", "display","-update","2", mfile, 0 );
	//execlp("display", "display", "-update", "2", "MAP.jpg", NULL);
  }
  else
  {
    while(1)
    {
      gets(infile);
      fd02 = open(mfile, O_RDONLY);
      stat(fd02, &st);
      ftruncate(fd02, st.st_size);
      addr = (char*)mmap(addr, st.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd02, 0);
      read(fd02, addr, st.st_size);
      msync(addr, st.st_size, 0);
      close(fd02);
    }
  }

  munmap(addr, st.st_size);
  close(fd01);


  return 0;
}