套接字 – 如何在luasocket库中检查套接字是否已关闭？

我在参考手册中找不到任何方法来检测套接字是否已关闭,只是尝试从中读取数据(在调用时它将返回nil和字符串’close’).

我的代码看起来像这样：

local socket = require 'socket'
local server = socket.tcp()
local port = 9527

server:bind('*',port)
local status,errorMessage = server:listen()
if status == 1 then
    printf('Server is launched successfully on port %u',port)
else
    printf('Server listen failed,error message is %s',errorMessage)
    return
end

local sockets = {server}

while true do
    local results = socket.select(sockets)
    for _,sock in ipairs(results) do
        if sock == server then
            local s = server:accept()

            callback('Connected',s)
            table.insert(sockets,s)

            printf('%s connected',s:getsockname())
        else
            -- trying to detect socket is closed
            if sock:isClosed() then
                callback('Disconnected',sock)

                for i,s in ipairs(sockets) do
                    if s == sock then
                        table.remove(sockets,i)
                        break
                    end
                end

                printf('%s disconnected',sock:getsockname())
            else
                callback('ReadyRead',sock)
            end
        end
    end
end