c++ - Linux 套接字和线程

Question

我正在 Linux 上编写一些 TCP 服务器代码，它正在使用 buildroot 工具链为 Pi 交叉编译。基本上我接受一个套接字然后创建一个线程来监听数据并处理它。为了进行测试，我使用 telnet 作为客户端。有时，当套接字关闭时，程序在线程清理期间崩溃，我不明白为什么。我最好的猜测是文件描述符很奇怪，但目前这主要是猜测。

代码如下:

void NetworkControl::startListening()
{
    mListenThread = std::thread(listener);
    mListenThread.detach();
}

void NetworkControl::listener()
{
    int sockfd, newsockfd, clilen;
    struct sockaddr_in serv_addr, cli_addr;

    int portno = 612;

    std::thread mWorkThread;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) 
       {} //print error

    bzero((char *) &serv_addr, sizeof(serv_addr));

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);
    if (bind(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) 
    { }//print error

    listen(sockfd,5);

    clilen = sizeof(cli_addr);

    while (1) { 
        newsockfd = accept(sockfd, 
            (struct sockaddr *) &cli_addr, (socklen_t*) &clilen);
        if (newsockfd < 0) {
            //print error
        }else{
            mWorkThread = std::thread(worker,newsockfd);
            mWorkThread.detach();
        }
    }
}

void NetworkControl::worker(int sock)
{
    uint32_t n;

    char *buf = new char(200);

    while(1){
        n = read(sock,&buf[0],199);;
        if (n <= 0){
            goto exit;
        }
        buf[n] = '\x00';
        printf("%s\n",buf);
    }
    exit:
    free(buf);
    close(sock);
}

这是崩溃的回溯:

#0  0x767c4e0c in raise () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libc.so.6
#1  0x767c60e4 in abort () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libc.so.6
#2  0x767fe2c8 in __libc_message () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libc.so.6
#3  0x76804790 in malloc_printerr () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libc.so.6
#4  0x76805850 in _int_free () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libc.so.6
#5  0x768a3c78 in tcache_thread_freeres () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libc.so.6
#6  0x768a3cdc in __libc_thread_freeres () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libc.so.6
#7  0x76f01f3c in start_thread () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libpthread.so.0
#8  0x768683b8 in ?? () from /home/david/Desktop/BR-Pi2/output/host/arm-buildroot-linux-gnueabihf/sysroot/lib/libc.so.6
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

控制台输出:

free() invalid next size (fast)

如果有人有任何想法，我将不胜感激!

Answer 1

正如已经告诉其他人的那样，崩溃是由 new() 与 free() 配对引起的，而您实际上需要 new[]/delete[]。

但是，使用 std::vector ，您甚至不必自己进行内存分配。 (示例代码未编译/测试)

void NetworkControl::worker(int sock)
{
    uint32_t n;

    std::vector<char> buf(200);

    while(1){
        n = read(sock, buf.data(), 199);
        if (n <= 0){
            break;
        }
        buf[n] = '\x00';
        printf("%s\n",buf.data());
    }
    close(sock);
}

对于 buf你也可以使用 C 风格的数组或 std::array<char> ，但是你必须确保你没有得到 stackoverflow。