#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

int setnonblock(int fd) {
   int fdflags;

   if ((fdflags = fcntl(fd, F_GETFL, 0)) == -1)
      return -1;
   fdflags |= O_NONBLOCK;
   if (fcntl(fd, F_SETFL, fdflags) == -1)
      return -1;
   return 0;
}