include std/pipeio.e as pipe

public sequence userLogin = ""

public function execCommand(sequence cmd)
  sequence s = ""
  object z = pipe:create()
  object p = pipe:exec(cmd, z)
  if atom(p) then
    printf(1, "Failed to exec() with error %x", pipe:error_no())
    pipe:kill(p)
	return -1
  end if
  object c = pipe:read(p[pipe:STDOUT], 256)
  while sequence(c) and length(c) do
    s &= c
    if atom(c) then
	  printf(1, "Failed on read with error %x", pipe:error_no())
      pipe:kill(p)
	  return -1
    end if
    c = pipe:read(p[pipe:STDOUT], 256)
  end while
  --Close pipes and make sure process is terminated
  pipe:kill(p)
  return s
end function

public function checkUser(sequence user)
  -- check user account
  sequence cmd = "grep "&user&" /etc/passwd | wc -l"
puts(1, "cmd = '"&cmd&"'\n")
  object un = execCommand(cmd)
  if atom(un) then
    puts(1, "Failed to verify user account\n")
    return 0
  end if
puts(1, "un = '"&un&"'\n")
  if equal(un, "1\n") then
    userLogin = user
    return 1
  else
    return 0
  end if
end function

public function checkPassword(sequence password)
  -- python is needed to ckeck user password
  -- check password
  if length(userLogin)=0 then return 0 end if
  sequence cmd = "grep "&userLogin&" /etc/shadow | cut -d':' -f2"
puts(1, "cmd = '"&cmd&"'\n")
  object pw = execCommand(cmd)
  if atom(pw) then
    puts(1, "Failed to verify user password\n")
    return 0
  end if
puts(1, "pw = '"&pw&"'\n")
  cmd = sprintf("python -c 'import crypt; print crypt.crypt(\"%s\",\"%s\")'",{password,pw[1..$-1]})
  object shadow = execCommand(cmd)
  if atom(shadow) then
    puts(1, "Failed to verify user password\n")
    return 0
  end if
puts(1, "shadow = '"&shadow&"'\n")
  -- Shadow password is correct when crypt("unencrypted password","crypted password") equals "crypted password"
  if equal(shadow, pw) then
    return 1
  else
    return 0
  end if
end function

/* Usage

include std/console.e
include checkUserAndPassword.e

  if checkUser("your_login") then
    puts(1, "User known, enter password\n")
    if checkPassword("your_password") then
      puts(1, "Password correct, you are now logged in\n")
    else
      puts(1, "Wrong password, user rejected\n")
    end if
  else
    puts(1, "User unknown, login rejected\n")
  end if

  Needs to be run as root!!!
*/