网络程序为什么要处理SIGPIPE

根据unix环境高级编程一书，我们知道管道在读端关闭时，写端继续写会引发SIGPIPE，而在网络（socket）连接的情况下，

如果接收端在发送端正在写的情况下关闭，发送端也会触发SIGPIPE，如果不处理该信号，那么程序就会崩溃。

测试代码：

服务端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define BUFFER_SIZE 8192

char buffer[BUFFER_SIZE];

void child_handle_send_recieve(int *client_fd);
int main() {
int rc;
int socket_fd;

int client_fd;
int reuse = 1;

socket_fd = socket(AF_INET, SOCK_STREAM, 0);
if (socket_fd < 0) {
perror("socket initial error");
}

struct sockaddr_in addr;
addr.sin_addr.s_addr = inet_addr("127.0.0.1");
addr.sin_family = AF_INET;
addr.sin_port = htons(1989);

rc = setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));
if (rc < 0) {
perror("set socket failed.");
}
rc = bind(socket_fd, (struct sockaddr*) &addr, sizeof(addr));
if (rc < 0) {
perror("bind failed");
}

rc = listen(socket_fd, 5);
if (rc < 0) {
perror("listen failed");
}

while (1) {
client_fd = rc = accept(socket_fd, NULL, 0);
if (rc < 0) {
perror("accept failed");
}
int fork_rt;
if ((fork_rt = fork()) < 0) {
perror("fork error");
} else if (fork_rt > 0) { // parent
close(client_fd);
} else { // child process.
close(socket_fd);
child_handle_send_recieve(&client_fd);
}
}
close(socket_fd);
return 0;
}

void child_handle_send_recieve(int *client) {
int client_fd = *client;
int rc;

memset(buffer, '\0', sizeof(buffer));
rc = recv(client_fd, buffer, BUFFER_SIZE, 0);
if (rc < 0) {
perror("receive failed");
}
printf("received:%s\n", buffer);

// close it now.
close(client_fd);
exit(0);
}

客户端：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <arpa/inet.h>
#include <fcntl.h>

#define BUFFER_SIZE 8192

int main(){

int socket_fd;
struct sockaddr_in addr;
char buf[BUFFER_SIZE];
int rc;
socket_fd = socket(AF_INET,SOCK_STREAM,0);

addr.sin_addr.s_addr = inet_addr("127.0.0.1");
addr.sin_family = AF_INET;
addr.sin_port = htons(1989);

rc = connect(socket_fd, (struct sockaddr*)&addr, sizeof(addr));
if(rc < 0){
perror("connect failed");
}

bzero(buf, sizeof(buf));
strncpy(buf,"hello man.",11);
while(1){
rc = send(socket_fd, buf,strlen(buf),0);
if(rc < 0){
perror("send failed");
}
}

// never can print.
printf("It's ok here????");
return 0;
}

用gdb调试之，客户端截图：