{-|
Module      : System.IO.Terminal.IO.Posix
Copyright   : (c) UU, 2019
License     : MIT
Maintainer  : Tom Smeding
Stability   : experimental
Portability : POSIX, macOS

Platform-specific submodule of "System.IO.Terminal.IO" that works on POSIX-like platforms.
-}
module System.IO.Terminal.IO.Posix (
    withWinchHandler,
) where

import Control.Exception (bracket)
import Control.Monad.IO.Unlift (MonadUnliftIO(..))
import Foreign.C.Types (CInt)
import System.Exit (die)
import System.Posix.Signals (installHandler, Handler(..))


sigWINCH :: CInt
sigWINCH = 28

-- | Install a SIGWINCH handler, then run the body, then uninstall. Uses
-- 'bracket'.
withWinchHandler :: MonadUnliftIO m => IO () -> m a -> m a
withWinchHandler h act =
    withRunInIO $ \run ->
        bracket (do prevh <- installHandler sigWINCH (Catch h) Nothing
                    case prevh of
                        Default -> return ()
                        Ignore -> return ()
                        _ -> die "ERROR: A signal handler was already installed for the WINCH signal!"
                    return prevh)
                (\prevh -> installHandler sigWINCH prevh Nothing)
                (\_ -> run act)