Computer Craft Login

--This is a VERY simple login script, slightly more complex than hardcoded login scripts although
--It will read a list of users from a file where a serialized list of users is stored. Before copying this
--to your startup script, please do create a users file and verify it functions as you wish.

local users = {}

term.clear()
term.setTextColor(colors.red)
print("MTech Launch System 1.0")
term.setTextColor(colors.white)
print("")

local usfile = "users"

if not fs.exists(usfile)then
    term.setTextColor(colors.red)
    print("Core file 'users.txt' not found!")
    term.setTextColor(colors.white)
    print("")
    sleep(1)
    os.reboot()
else
    local file = io.open("users", "r")
    local data = textutils.unserialize(file:read("*a"))
    file:close()
    if data == nil then
        term.setTextColor(colors.red)
        print("User entry data file is empty!")
        term.setTextColor(colors.white)
        print("")
        sleep(1)
        os.reboot()
    else
        users = data.users
    end
end

local function CheckUSR(name)
    if name == nil then return false end
    for k, v in pairs(users)do
        if(name == k)then return true else return false end
    end
end

local function CheckPassword(name, pass)
    if name == nil then return false end
    if pass == nil then return false end
    for k, v in pairs(users)do
        if(k == name)then
            if(pass == v)then
                return true
            else
                return false
            end
        end
    end
    return false
end

local function SetUp()
    term.clear()
    term.setCursorPos(1, 1)
    term.setTextColor(colors.red)
    textutils.slowPrint("MTech Mainframe Controller")
    term.setTextColor(colors.white)
    print("")
    if(fs.exists("init"))then
        dofile("init")
    end
end

term.clear()
term.setCursorPos(1, 1)
term.setTextColor(colors.red)
print("Login Area")
term.setTextColor(colors.white)
print("")
print("Username:")
local username = read()
if(CheckUSR(username) == false)then
    term.setTextColor(colors.red)
    print("Unknown Username!")
    term.setTextColor(colors.white)
    sleep(1)
    os.reboot()
else
    print("Password:")
    local password = read()
    if(CheckPassword(username, password) == false)then
        term.setTextColor(colors.red)
        print("Incorrect Password!")
        sleep(1)
        os.reboot()
    elseif(CheckPassword(username, password) == true)then
        term.setTextColor(colors.green)
        print("Welcome "..username.."!")
        term.setTextColor(colors.white)
        print("")
        SetUp()
    end
end