1 files changed, 37 insertions, 0 deletions
diff --git a/src/System/IO/Terminal/IO/Posix.hs b/src/System/IO/Terminal/IO/Posix.hs
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+++ b/src/System/IO/Terminal/IO/Posix.hs
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+{-|
+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)