网络IO 之 信号驱动型io

#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <fcntl.h>
#include <netinet/in.h>
int sockfd;
//信号处理函数
void sig_func(int arg)
{
  printf("the signal is %d\n",arg);
  char buff[256]={0};
  int ret = read(sockfd,buff,sizeof(buff));
  printf("read buff == %s , len = %d\n",buff,ret);
  write(sockfd,buff,ret);
}
int main(int agrc,char * argv[])
{
//建立udp的套接字
  sockfd = socket(AF_INET,SOCK_DGRAM,0);
  if(sockfd < 0)
  {
    perror("socket");
    return -1;
  }
//初始化信号处理函数
  struct sigaction mysig;
  mysig.sa_handler = sig_func;
  mysig.sa_flags = 0;
  sigaction(SIGIO,&mysig,NULL);
//绑定端口信息
  struct sockaddr_in addr;
  memset(&addr,0,sizeof(struct sockaddr_in));
  addr.sin_family = AF_INET;
  addr.sin_port = htons(9999);
  addr.sin_addr.s_addr = INADDR_ANY;
//设置属性,将fd加入到本进程
  fcntl(sockfd,F_SETOWN,getpid());
//设置同步 非阻塞状态
  int flag = fcntl(sockfd,F_GETFL,0);
  flag = O_ASYNC | O_NONBLOCK;
  fcntl(sockfd,F_SETFL,flag);
//bind
  int ret = bind(sockfd,(struct sockaddr *)&addr,sizeof(struct sockaddr));
  if(ret < 0)
  {
    perror("bind");
    return -2;
  }
  while(1)  sleep(1);
  close(sockfd);
  return 0;
}