如何将套接字重新设置为阻塞模式(在我设置为非阻塞模式后)?

I have read this regarding setting a socket to non-blocking mode.

我已经读过关于将套接字设置为非阻塞模式。

http://www.gnu.org/software/libc/manual/html_mono/libc.html#File-Status-Flags

http://www.gnu.org/software/libc/manual/html_mono/libc.html File-Status-Flags

Here is what I did:

以下是我所做的:

static void setnonblocking(int sock)
{
    int opts;

    opts = fcntl(sock,F_GETFL);
    if (opts < 0) {
        perror("fcntl(F_GETFL)");
        exit(EXIT_FAILURE);
    }
    opts = (opts | O_NONBLOCK);
    if (fcntl(sock,F_SETFL,opts) < 0) {
        perror("fcntl(F_SETFL)");
        exit(EXIT_FAILURE);
    }
    return;
}

How can I set the socket back to Blocking mode? I don't see a O_BLOCK flag?

如何将套接字设置回阻塞模式?我没有看到O_BLOCK标志?

Thank you.

谢谢你！

3 个解决方案

#1

Did you try clearing the O_NONBLOCK flag?

您试过清除O_NONBLOCK标志吗?

opts = opts & (~O_NONBLOCK)

#2

Here is a more cross-platform capable solution:

这是一个更加跨平台的解决方案:

bool set_blocking_mode(const int &socket, bool is_blocking)
{
    bool ret = true;

#ifdef WIN32
    /// @note windows sockets are created in blocking mode by default
    // currently on windows, there is no easy way to obtain the socket's current blocking mode since WSAIsBlocking was deprecated
    u_long non_blocking = is_blocking ? 0 : 1;
    ret = NO_ERROR == ioctlsocket(socket, FIONBIO, &non_blocking);
#else
    const int flags = fcntl(socket, F_GETFL, 0);
    if ((flags & O_NONBLOCK) && !is_blocking) { info("set_blocking_mode(): socket was already in non-blocking mode"); return ret; }
    if (!(flags & O_NONBLOCK) && is_blocking) { info("set_blocking_mode(): socket was already in blocking mode"); return ret; }
    ret = 0 == fcntl(socket, F_SETFL, is_blocking ? flags ^ O_NONBLOCK : flags | O_NONBLOCK));
#endif

    return ret;
}

#3

Alternative way to clear the flag:

清除旗帜的替代方法:

opts ^= O_NONBLOCK;

This will toggle the non-blocking flag, i.e. disable non-blocking if currently enabled.

这将切换非阻塞标志，即如果当前启用，禁用非阻塞标记。

#1