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10-1-unify-signal.c
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10-1-unify-signal.c
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#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/epoll.h>
#include <pthread.h>
#include <fcntl.h>
#define MAX_EVENT_NUMBER 1024
static int pipefd[2];
int setnonblocking(int fd)
{
int old_option = fcntl(fd, F_GETFL);
int new_option = old_option | O_NONBLOCK;
fcntl(fd, F_SETFL, new_option);
return old_option;
}
void addfd(int epollfd, int fd)
{
epoll_event event;
event.data.fd = fd;
event.events = EPOLLIN | EPOLLET;
epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
setnonblocking(fd);
}
/*信号处理函数*/
void sig_handler(int sig)
{
/* 保留原来的errno, 在函数最后恢复,以保证函数的可重入性
* */
int save_errno = errno;
int msg = sig;
send(pipefd[1], (char *)&msg, 1, 0); /*将信号值写入管道,以通知主循环*/
errno = save_errno;
}
/* 设置信号处理函数
* */
void addsig(int sig)
{
struct sigaction sa;
memset(&sa, '\0', sizeof(sa));
sa.sa_handler = sig_handler;
sa.sa_flags = SA_RESTART;
sigfillset(&sa.sa_mask);
assert(sigaction(sig, &sa, NULL) != -1);
}
int main(int argc, const char *argv[])
{
if (argc <= 2)
{
fprintf(stderr, "usage: %s ip_address port_number\n", basename(argv[0]));
return 1;
}
const char *ip = argv[1];
int port = atoi(argv[2]);
int ret = 0;
struct sockaddr_in address;
bzero(&address, sizeof(address));
address.sin_family = AF_INET;
inet_pton(AF_INET, ip, &address.sin_addr);
address.sin_port = htons(port);
int listenfd = socket(PF_INET, SOCK_STREAM, 0);
assert(listenfd >= 0);
ret = bind(listenfd, (struct sockaddr *)&address, sizeof(address));
if (ret == -1)
{
fprintf(stderr, "bind error, errno is:%d, errstr:%s\n", errno, strerror(errno));
return 1;
}
ret = listen(listenfd, 5);
assert(ret != -1);
epoll_event events[MAX_EVENT_NUMBER];
int epollfd = epoll_create(5);
assert(epollfd != -1);
addfd(epollfd, listenfd);
/*使用socketpair创建管道, 注册pipefd[0]上的可读事件*/
ret = socketpair(PF_UNIX, SOCK_STREAM, 0, pipefd);
assert( ret != -1);
setnonblocking(pipefd[1]);
addfd(epollfd, pipefd[0]);
/*设置一些信号的处理函数*/
addsig(SIGHUP);
addsig(SIGCHLD);
addsig(SIGTERM);
addsig(SIGINT);
bool stop_server = false;
while(!stop_server)
{
int number = epoll_wait(epollfd, events, MAX_EVENT_NUMBER, -1);
if ((number < 0) && (errno != EINTR))
{
fprintf(stderr, "epoll wait failure!\n");
break;
}
for(int i = 0; i < number; i++)
{
int sockfd = events[i].data.fd;
/*如果就绪的文件描述符是listenfd,则处理新的连接*/
if (sockfd == listenfd)
{
struct sockaddr_in client_address;
socklen_t client_addrlength = sizeof(client_address);
int connfd = accept(listenfd, (struct sockaddr *)&client_address, &client_addrlength);
addfd(epollfd, connfd);
}
/*如果就绪的文件描述符是pipefd[0], 则处理信号*/
else if ((sockfd == pipefd[0]) && (events[i].events & EPOLLIN))
{
char signals[1024];
ret = recv(pipefd[0], signals, sizeof(signals), 0);
if (ret == -1)
{
continue;
}
else if (ret == 0)
{
continue;
}
else
{
/* 因为每个信号值占1字节,所以按字节来逐个接收信号。我们以SIGTERM
* 为例,来说明如何安全地终止服务器主循环
*/
for(int i = 0; i < ret; i++)
{
switch (signals[i])
{
case SIGCHLD:
case SIGHUP:
{
continue;
}
case SIGTERM:
case SIGINT:
{
stop_server = true;
}
}
}
}
}
else
{
}
}
}
fprintf(stderr, "close fds\n");
close(listenfd);
close(pipefd[1]);
close(pipefd[0]);
return 0;
}