Question

考虑下一段代码 -

int get_ready_connection(int s) {
    /* socket of connection */
    int caller;
    if ((caller = accept(s,NULL,NULL)) < SUCCESS)
    {
        server_log->write_to_log(sys_call_error(SERVER, "accept"));
        return FAILURE;
    }

    return caller;
}


int establish_connection(sockaddr_in& connection_info)
{
    // Create socket
    if ((server_sock = socket(AF_INET, SOCK_STREAM, 0)) < SUCCESS)
    {
        server_log->write_to_log(sys_call_error(SERVER, "socket"));
        return FAILURE;
    }

    // Bind `sock` with given addresses
    if (bind(server_sock, (struct sockaddr *) &connection_info, \
             sizeof(struct sockaddr_in)) < SUCCESS)
    {
        close(server_sock);
        server_log->write_to_log(sys_call_error(SERVER, "bind"));
        return FAILURE;
    }

    // Max # of queued connects
    if (listen(server_sock, MAX_PENDING_CONNECTIONS) < SUCCESS)
    {
        server_log->write_to_log(sys_call_error(SERVER, "listen"));
        return FAILURE;
    }

    // Create a set of file descriptors and empty it.
    fd_set set;
    bool is_inside;
    int ret_val;

    while(true)
    {
        FD_ZERO(&set);

        FD_SET(STDIN_FILENO, &set);
        FD_SET(server_sock, &set);

        struct timeval tv = {2, 0};

        ret_val = select(server_sock + 1, &set, NULL, NULL, &tv); // TODO ret_val

        is_inside = FD_ISSET(STDIN_FILENO, &set);
        if(is_inside)
        {
            // get user input
            string user_input;
            getline(cin, user_input);

            if ((strcasecmp(user_input.c_str(), EXIT_TEXT) == 0))
            {
                return SUCCESS;
            }
        }

        is_inside = FD_ISSET(server_sock, &set);
        if(is_inside)
        {
            // get the first connection request
            int current_connection = get_ready_connection(server_sock);
            if (current_connection == FAILURE) {
                free_allocated_memory();
                exit_write_close(server_log, sys_call_error(SERVER, "accept"),
                                 ERROR);
            }

            // if exit was not typed by the server's stdin, process the request
            pthread_t thread;

            // create thread
            if (pthread_create(&thread, NULL, command_thread_func, &current_connection) != 0)
            {
                free_allocated_memory();
                exit_write_close(server_log, sys_call_error(SERVER, "pthread_create"), ERROR);
            }
        }
    }
}

我试图做的就是“监听”STDIN，让用户在服务器的shell中键入“EXIT”，并等待客户端从shell发送命令（每次服务器从服务器接收命令时）用户，服务器解析它，服务器创建一个处理命令执行的线程）为了同时做到这一点，我使用了select（）。

当我使用单个线程时，一切都很完美。但问题是当我连接另一个客户端时，我得到一个seg故障。我怀疑问题就在这里。有什么建议吗？

Answer 1

很难知道这是否是您的确切问题，但这肯定是问题：

您无法调用pthread_create并提供指向堆栈变量（&current_connection）的指针作为线程函数的参数。首先，一旦父母退出该范围，它就会立即遭到破坏。

其次，它将在下次调用get_ready_connection时被覆盖。

使用pthreads和select（）

1 个答案: