1、pipe的关闭消息会被对端的epoll_wait捕获，但数据长度是0，可据此判断为pipe关闭消息。
2、epoll_wait返回的events中，当用户在epoll_ctl时设置了data.ptr，则不返回data.fd，用户只能使用data.ptr，因此自定义的结构中处理用户数据信息外，需要包含对应连接的socket描述符fd，否则无法收发数据。
代码：
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <arpa/inet.h> // htons
#include <string.h> // bzero
//#include <fcntl.h>
int main(int argc, char* argv[])
{
pid_t child;
int pipefd[2];
int e_fd = epoll_create(10);
if (-1 == e_fd)
{
perror("epoll_create");
exit(1);
}
pipe(pipefd);
printf("fd0: %d, fd1: %d \n",pipefd[0], pipefd[1]);
if ((child = fork()) == -1)
{
perror("fork");
close(e_fd);
exit(1);
}
if (child == 0)
{
close(pipefd[0]);
sleep(1);
write(pipefd[1],"a", 1);
sleep(2);
write(pipefd[1],"b",1);
sleep(3);
close(pipefd[1]);
// socket
{
int fd, status;
struct sockaddr_in remote;
remote.sin_family = AF_INET;
remote.sin_port = htons(5930);
remote.sin_addr.s_addr = inet_addr("192.168.1.213");
fd = socket(AF_INET, SOCK_STREAM, 0);
sleep(3);
status = connect(fd, (struct sockaddr*)&remote, sizeof(struct sockaddr));
if (status == -1)
{
perror("connect");
close(fd);
exit(1);
}
sleep(2);
if (send(fd, "hello", 5, 0) == -1)
{
perror("send");
}
close(fd);
}
}
else
{
struct epoll_event evs[10];
struct epoll_event ev;
struct P_ATR{
int fd;
} pipe_atr;
int nds = 0, i;
close(pipefd[1]);
pipe_atr.fd = pipefd[0];
ev.data.fd = pipefd[0];
//ev.data.ptr = &pipe_atr; // 不传入data.ptr
ev.events = EPOLLIN;
epoll_ctl(e_fd, EPOLL_CTL_ADD, pipefd[0], &ev);
//sleep(5);
nds = epoll_wait(e_fd, evs, 10, -1);
printf("epoll_wait ret %d\n", nds);
for (i = 0; i < nds; i++)
{
int fd;
printf("evs[%d].data.fd: %d, ", i, fd = evs[i].data.fd); // 我们在上面没有传入data.ptr，此时系统会返回data.fd
// printf("event fd: %d\n", fd = ((struct P_ATR*)(evs[i].data.ptr))->fd);
if ( fd == pipefd[0])
{
char readbuf[80];
int readbytes = read(pipefd[0], readbuf, 1);
readbuf[readbytes] = 0;
printf ("pipe event catch, recvdata = %s, size = %d\n", readbuf, readbytes);
}
}
ev.events = EPOLLIN;
epoll_ctl(e_fd, EPOLL_CTL_MOD, pipefd[0], &ev);
nds = epoll_wait(e_fd, evs, 10, -1);
printf("epoll_wait ret %d\n", nds);
for (i = 0; i < nds; i++)
{
int fd;
printf("evs[%d].data.fd: %d, ", i, fd = evs[i].data.fd);
// printf("event fd: %d\n", fd = ((struct P_ATR*)(evs[i].data.ptr))->fd);
if ( fd == pipefd[0])
{
char readbuf[80];
int readbytes = read(pipefd[0], readbuf, 1);
readbuf[readbytes] = 0;
printf ("pipe event catch, recvdata = %s, size = %d\n", readbuf, readbytes);
}
}
epoll_ctl(e_fd, EPOLL_CTL_MOD, pipefd[0], &ev);
nds = epoll_wait(e_fd, evs, 10, -1);
printf("epoll_wait ret %d\n", nds);
for (i = 0; i < nds; i++)
{
int fd;
printf("evs[%d].data.fd: %d, ", i, fd = evs[i].data.fd);
// printf("event fd: %d\n", fd = ((struct P_ATR*)(evs[i].data.ptr))->fd);
if ( fd == pipefd[0])
{
char readbuf[80];
int readbytes = read(pipefd[0], readbuf, 1);
readbuf[readbytes] = 0;
printf ("pipe event catch, recvdata = %s, size = %d\n", readbuf, readbytes);
}
}
close(pipefd[0]);
// socket
{
struct sockaddr_in addr;
struct sockaddr_in remote;
int newfd;
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (-1 == sockfd)
{
perror("socket");
exit(0);
}
printf("new socket fd: %d\n", sockfd);
addr.sin_family = AF_INET;
addr.sin_port = htons(5930);
addr.sin_addr.s_addr = INADDR_ANY;
bzero(&addr.sin_zero, 8);
if (bind(sockfd, (struct sockaddr*)&addr, sizeof(struct sockaddr)) == -1)
{
perror("bind");
close(sockfd);
exit(1);
}
pipe_atr.fd = sockfd;
ev.data.fd = sockfd;
ev.data.ptr = &pipe_atr; // 传入data.ptr
ev.events = EPOLLIN;
epoll_ctl(e_fd, EPOLL_CTL_ADD, sockfd, &ev);
if (listen(sockfd, 5) == -1)
{
perror("listen");
exit(1);
}
nds = epoll_wait(e_fd, evs, 10, -1);
printf("epoll_wait ret %d\n", nds);
for (i = 0; i < nds; i++)
{
int fd;
socklen_t len;
int inds;
printf("evs[%d].data.fd: %d, ", i, evs[i].data.fd); // 系统不会回填data.fd，其值是随机数字
printf("event fd: %d\n", fd = ((struct P_ATR*)(evs[i].data.ptr))->fd); // 系统返回用户传入的data.ptr
if ( fd == sockfd)
{
len = sizeof (struct sockaddr);
newfd = accept(sockfd, (struct sockaddr*)&remote, &len);
if (-1 == newfd)
{
perror("accept");
close(sockfd);
exit(1);
}
printf("new link create success, fd: %d\n", newfd);
struct P_ATR new_atr;
new_atr.fd = newfd;
ev.data.fd = newfd;
ev.data.ptr = &new_atr;
ev.events = EPOLLIN;
epoll_ctl(e_fd, EPOLL_CTL_ADD, newfd, &ev);
inds = epoll_wait(e_fd, evs, 10, -1);
printf("epoll_wait ret %d\n", inds);
for (i = 0; i < inds; i++)
{
int fd;
printf("evs[%d].data.fd: %d, ", i, evs[i].data.fd);
printf("event fd: %d\n", fd = ((struct P_ATR*)(evs[i].data.ptr))->fd);
if ( fd == newfd)
{
char readbuf[80];
int readbytes = read(fd, readbuf, sizeof(readbuf));
readbuf[readbytes] = 0;
printf ("pipe event catch, dataptr = %p, recvdata = %s, size = %d\n", evs[i].data.ptr, readbuf, readbytes);
}
}
close(newfd);
close(sockfd);
}
}
}
}
close(e_fd);
return 0;
}