標準io 與 shutdown 半關閉

把文件描述符轉標準io FILE 時 (例如: FILE readfp = fdopen(fd,"r") )
若是須要半關閉, 不能使用fclose ,fclose 將直接關閉(close)套接字
仍是須要shutdown 來幫忙 (例如 shutdown(fileno(readfp),SHUT_WR) ) ,先把 FILE* 轉描述符,再調用shutdown;

代碼:

serv.c

int sock = socket(AF_INET,SOCK_STREAM,0);
    struct sockaddr_in serv_addr,cli_addr;
    memset(&serv_addr,0,sizeof(serv_addr));
    memset(&cli_addr,0,sizeof(cli_addr));
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(PORT);
    serv_addr.sin_family = AF_INET;
    socklen_t  cli_socklen = sizeof(cli_addr);
    bind(sock,(SA*)&serv_addr,sizeof(serv_addr));
    listen(sock,10);
    int cli_sock = accept(sock,(SA*)&cli_addr,&cli_socklen);
    
    //把套接字轉成標準io
    FILE* readfp = fdopen(cli_sock,"r");  //讀指針
    FILE* writefp = fdopen(cli_sock,"w"); //寫指針
    
    fputs("fuck you 1", writefp);
    fputs("fuck you 2", writefp);
    fputs("fuck you 3", writefp);
    fflush(writefp);

//    fclose(writefp);  這樣將直接close, 下面的fgets 將收不到數據了

    shutdown(fileno(writefp),SHUT_WR);  // 仍是使用shutdown 來半關閉
    puts("after shutdown");
    system("netstat -a | grep 9988");
    getchar();
    char buf[100] = {0};
    if(fgets(buf,100,readfp) == NULL){
        puts(" ******** peer closed ********* ");
    }
    printf("read : %s\n",buf);
    fclose(readfp);
    puts("fclose read");
    system("netstat -a | grep 9988");

client.c

if(argc !=3){
        puts("ip port");
        return 0;
    }
    int sock = socket(AF_INET,SOCK_STREAM,0);
    struct sockaddr_in serv_addr;
    memset(&serv_addr,0,sizeof(serv_addr));
    serv_addr.sin_family=AF_INET;
    serv_addr.sin_port = htons(atoi(argv[2]));
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
    connect(sock,(SA*)&serv_addr,sizeof(serv_addr));
    
    //把描述符轉成標準io
    FILE * readfp = fdopen(sock,"r");
    FILE* writefp = fdopen(sock,"w");
    char buf[100];
    while(1){
        if(fgets(buf,sizeof(buf),readfp) == NULL){
            puts("server closed");
            break;
        }
        printf("buf:%s\n",buf);
        fflush(stdout);
    }
    fputs("byebye",writefp);
    fflush(writefp);
    puts("continue");
    getchar();
    fclose(writefp);
    fclose(readfp);