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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 Plugins.PipeReader where
import System.IO
import Plugins
import System.Posix.Files
import Control.Concurrent(threadDelay)
import Control.Exception
import Control.Monad(when)
data PipeReader = PipeReader String String
deriving (Read, Show)
instance Exec PipeReader where
alias (PipeReader _ a) = a
start (PipeReader p _) cb = do
let (def, pipe) = split ':' p
when (not $ null def) (cb def)
checkPipe pipe
h <- openFile pipe ReadWriteMode
forever (hGetLineSafe h >>= cb)
where
forever a = a >> forever a
split c xs | c `elem` xs = let (pre, post) = span ((/=) c) xs
in (pre, dropWhile ((==) c) post)
| otherwise = ([], xs)
checkPipe :: FilePath -> IO ()
checkPipe file = do
handle (\(SomeException _) -> waitForPipe) $ do
status <- getFileStatus file
if isNamedPipe status
then return ()
else waitForPipe
where waitForPipe = threadDelay 1000 >> checkPipe file
|
