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+{-# LANGUAGE DeriveDataTypeable, CPP #-}
+
+-----------------------------------------------------------------------------
+-- |
+-- Module : Signal
+-- Copyright : (c) Andrea Rosatto
+-- : (c) Jose A. Ortega Ruiz
+-- : (c) Jochen Keil
+-- License : BSD-style (see LICENSE)
+--
+-- Maintainer : Jose A. Ortega Ruiz <jao@gnu.org>
+-- Stability : unstable
+-- Portability : unportable
+--
+-- Signal handling, including DBUS when available
+--
+-----------------------------------------------------------------------------
+
+module Xmobar.Signal where
+
+import Data.Foldable (for_)
+import Data.Typeable (Typeable)
+import Control.Concurrent
+import Control.Concurrent.STM
+import Control.Exception
+import System.Posix.Signals
+import Graphics.X11.Types (Button)
+import Graphics.X11.Xlib.Types (Position)
+import System.IO
+
+#ifdef DBUS
+import DBus (IsVariant(..))
+import Control.Monad ((>=>))
+#endif
+
+import Xmobar.Plugins.Utils (safeHead)
+
+data WakeUp = WakeUp deriving (Show,Typeable)
+instance Exception WakeUp
+
+data SignalType = Wakeup
+ | Reposition
+ | ChangeScreen
+ | Hide Int
+ | Reveal Int
+ | Toggle Int
+ | TogglePersistent
+ | Action Button Position
+ deriving (Read, Show)
+
+#ifdef DBUS
+instance IsVariant SignalType where
+ toVariant = toVariant . show
+ fromVariant = fromVariant >=> parseSignalType
+#endif
+
+parseSignalType :: String -> Maybe SignalType
+parseSignalType = fmap fst . safeHead . reads
+
+-- | Signal handling
+setupSignalHandler :: IO (TMVar SignalType)
+setupSignalHandler = do
+ tid <- newEmptyTMVarIO
+ installHandler sigUSR2 (Catch $ updatePosHandler tid) Nothing
+ installHandler sigUSR1 (Catch $ changeScreenHandler tid) Nothing
+ return tid
+
+updatePosHandler :: TMVar SignalType -> IO ()
+updatePosHandler sig = do
+ atomically $ putTMVar sig Reposition
+ return ()
+
+changeScreenHandler :: TMVar SignalType -> IO ()
+changeScreenHandler sig = do
+ atomically $ putTMVar sig ChangeScreen
+ return ()
+
+
+-- | Ensures that the given IO action runs its cleanup actions ('bracket' etc.),
+-- even if a signal is caught.
+--
+-- An exception will be thrown on the thread that called this function when a
+-- signal is caught.
+withDeferSignals :: IO a -> IO a
+withDeferSignals thing = do
+ threadId <- myThreadId
+ caughtSignal <- newEmptyMVar
+
+ let signals =
+ filter (not . flip inSignalSet reservedSignals)
+ [ sigQUIT
+ , sigTERM
+ --, sigINT -- Handler already installed by GHC
+ --, sigPIPE -- Handler already installed by GHC
+ --, sigUSR1 -- Handled by setupSignalHandler
+ --, sigUSR2 -- Handled by setupSignalHandler
+
+ -- One of the following appears to cause instability, see #360
+ --, sigHUP
+ --, sigILL
+ --, sigABRT
+ --, sigFPE
+ --, sigSEGV
+ --, sigALRM
+ --, sigBUS
+ --, sigPOLL
+ --, sigPROF
+ --, sigSYS
+ --, sigTRAP
+ --, sigVTALRM
+ --, sigXCPU
+ --, sigXFSZ
+ ]
+
+ for_ signals $ \s ->
+
+ installHandler s
+ (Catch $ do
+ tryPutMVar caughtSignal s
+ hPutStrLn stderr ("xmobar: Caught signal "++show s++"; exiting...")
+ throwTo threadId ThreadKilled)
+ Nothing
+
+ thing `finally` do
+ s0 <- tryReadMVar caughtSignal
+ case s0 of
+ Nothing -> pure ()
+ Just s -> do
+ -- Run the default handler for the signal
+ -- hPutStrLn stderr ("xmobar: Running default handler for signal "++show s)
+ installHandler s Default Nothing
+ raiseSignal s