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+-----------------------------------------------------------------------------
+-- |
+-- Module : Plugins.PipeReader
+-- Copyright : (c) Andrea Rossato
+-- License : BSD-style (see LICENSE)
+--
+-- Maintainer : Jose A. Ortega Ruiz <jao@gnu.org>
+-- Stability : unstable
+-- Portability : unportable
+--
+-- A plugin for reading from named pipes
+--
+-----------------------------------------------------------------------------
+
+module Xmobar.Plugins.PipeReader(PipeReader(..)) where
+
+import System.IO
+import Xmobar.Utils(hGetLineSafe)
+import Xmobar.Run.Commands(Exec(..))
+import Xmobar.System.Environment(expandEnv)
+import System.Posix.Files
+import Control.Concurrent(threadDelay)
+import Control.Exception
+import Control.Monad(forever, unless)
+import Control.Applicative ((<$>))
+
+data PipeReader = PipeReader String String
+ deriving (Read, Show)
+
+instance Exec PipeReader where
+ alias (PipeReader _ a) = a
+ start (PipeReader p _) cb = do
+ (def, pipe) <- split ':' <$> expandEnv p
+ unless (null def) (cb def)
+ checkPipe pipe
+ h <- openFile pipe ReadWriteMode
+ forever (hGetLineSafe h >>= cb)
+ where
+ split c xs | c `elem` xs = let (pre, post) = span (c /=) xs
+ in (pre, dropWhile (c ==) post)
+ | otherwise = ([], xs)
+
+checkPipe :: FilePath -> IO ()
+checkPipe file =
+ handle (\(SomeException _) -> waitForPipe) $ do
+ status <- getFileStatus file
+ unless (isNamedPipe status) waitForPipe
+ where waitForPipe = threadDelay 1000000 >> checkPipe file