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：