systemd-socket-activation-1: src/SocketActivation/CheckRecipient.hs

-- | Verification of the socket recipient PID

module SocketActivation.CheckRecipient where

import           Control.Monad             (Monad (return, (>>=)))
import           Control.Monad.IO.Class    (MonadIO (liftIO))
import           Data.Either               (Either)
import           Data.Eq                   (Eq ((==)))
import           Data.Function             ((.))
import           System.IO                 (IO)

import qualified System.Posix.Process      as Sys

import           SocketActivation.Concepts
import           SocketActivation.Env
import           SocketActivation.IO

checkRecipient :: IO (Either Error ())
checkRecipient = run (getIt >>= checkIt)
  where
    getIt = IO' (getEnv' @Recipient)
    checkIt = IO' . checkRecipient'

checkRecipient' :: Recipient -> IO (Either Error ())
checkRecipient' x = run (getMyPid >>= throwIfDifferent)
  where
    getMyPid = liftIO Sys.getProcessID
    throwIfDifferent y = if recipientPID x == y then return () else throwError WrongProcess