poll.c

#include <sys/epoll.h>
#include <sys/socket.h>
#include <stdio.h>
int main()
{
  struct epoll_event ev = {
    .data.fd = 1
  };
  int efd = epoll_create(1);
  ev.events = EPOLLIN|EPOLLET;
  epoll_ctl(efd, EPOLL_CTL_ADD, 1, &ev);
  while (1) {
    struct epoll_event ee;
    char buf[512];
    epoll_wait(efd,&ee,1,-1);
    int n = recv(1,buf,512,MSG_PEEK|MSG_DONTWAIT);
    fprintf(stderr,"%d bytes pending\n", n);
  }
  return 0;
}