protect

computer=require("computer")
getPath=require("filesystem").path
fs=require("component").proxy(computer.getBootAddress())

function computer.addUser()
  return nil, "Function 'addUser' is disabled"
end

local protectList
local function checkPath(path)
  return true
end

local function whiteList(path)
  if fs.isDirectory(path) then path=path.."/" end
  if protectList["/"] then return true end
  repeat
    if protectList[path] then return true end
    path=getPath(path)
  until path=="/"
  return nil, "no such file, or permission denied"
end

local function blackList(path)
  if fs.isDirectory(path) then path=path.."/" end
  if protectList["/"] then return nil, "no such file, or permission denied" end
  repeat
    if protectList[path] then return nil, "no such file, or permission denied" end
    path=getPath(path)
  until path=="/"
  return true
end

do
  local env = {}
  local config = loadfile("/etc/protect.cfg", nil, env)
  if config then
    pcall(config)
    if env.writeEnabled then
      protectList={}
      for i=1,#env.writeEnabled do
        protectList[env.writeEnabled[i]]=true
      end
      checkPath=whiteList
    end
    if env.writeDisabled then
      protectList={}
      for i=1,#env.writeDisabled do
        protectList[env.writeDisabled[i]]=true
      end
      checkPath=blackList
    end
  end
end

local nativeFS={}

nativeFS.makeDirectory=fs.makeDirectory
function fs.makeDirectory(path)
  local ok,err=checkPath(path)
  if not ok then return nil, err end
  return nativeFS.makeDirectory(path)
end

nativeFS.remove=fs.remove
function fs.remove(path)
  local ok,err=checkPath(path)
  if not ok then return nil, err end
  return nativeFS.remove(path)
end

nativeFS.rename=fs.rename
function fs.rename(from,to)
  local ok,err=checkPath(from)
  if not ok then return nil, err end
  ok,err=checkPath(to)
  if not ok then return nil, err end
  return nativeFS.rename(from,to)
end

nativeFS.open=fs.open
function fs.open(path, mode)
  if mode=="w" or mode=="wb" or mode=="a" or mode=="ab" then
    local ok,err=checkPath(path)
    if not ok then return nil, err end
  end
  return nativeFS.open(path,mode)
end