computer craft startup login with password hashing v1.2

-- by morganamilo ([email protected])

--to add to startup run this program in startup (shell.run('file name'))
--or name this file startup

--usernames = the file name at /users/
--passwords is data in the file (hashed)

--downloads my hash program if not on pc

--'ProgramName user1 pass1' creates an account on the turtle with
--username: user1
--password: pass1

if fs.exists('/hash') == false then
  print('no hash program found, downloading...')
  shell.run('pastebin get VPuGKaBy /hash')
end

local oldPull = os.pullEvent
os.pullEvent = os.pullEventRaw

os.loadAPI('/hash')

if fs.exists('/users/') == false then
    shell.run('mkdir /users/')
end

local args = {...}

if args[1] ~= 'new' and args[1] ~= 'delete' and args[1] ~= 'login' and args[1] ~= nil then
  local name = shell.getRunningProgram()
  print('Usages:\n' .. name .. ' login\n' .. name.. ' new <username> <password>\n' .. name .. ' delete <username>')
  error()
end

function logIn()
  local pass

  if fs.list('/users/')[1] == null and (args[1] == 'login' or args[1] == nil) then
    print('cant begin login, no accounts exis')
    local name = shell.getRunningProgram()
    print('Usages:\n' .. name .. ' login\n' .. name.. ' new <username> <password>\n' .. name .. ' delete <username>')
    os.pullEvent = oldPull
    error()
  end

  while true do
    io.write('username: ')
    local inUser = read()
    io.write('password: ')
    local inPass = read('*')
    if inPass ~= '' then
      inPass = hash.sha256(inPass)
      end

    local empty = ""

    if inUser ~= empty and inPass ~= empty and fs.exists('/users/' .. inUser) then
      local userFile = fs.open('/users/' .. inUser, 'r')
      pass = userFile.readAll()
      userFile.close()
    end

      if pass == inPass then
        break
      else
        print('username or password is incorrect\n')
        inPass = empty
        inUser = empty
      end

  end

  term.clear()
  term.setCursorPos(1, 1)
  print('Welcome')
end

function newUser(user, pass)
  if fs.exists('/users/' .. user) then
    print('user already exists')
  else
    local userFile = fs.open('/users/' .. user, 'w')
    pass = hash.sha256(pass)
    userFile.write(pass)
    userFile.close()
  end
end

function deleteUser(user)
  if fs.exists('/users/' .. user) ~= true then
    print('user doesnt exist')
  else
    fs.delete('/users/' .. user)
    print('done\n')
  end
end

if args[1] == 'new' and args[3] ~= nil then
  newUser(args[2],args[3])

elseif args[1] == 'login' or args[1] == nil then
  logIn()

elseif args[1] == 'delete' and args[2] ~= nil then
  deleteUser(args[2])
end

os.unloadAPI('/hash')
os.pullEvent = oldPull