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|
{-# LANGUAGE ViewPatterns #-}
-----------------------------------------------------------------------------
-- |
-- Module : Plugins.StdinReader
-- 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 `stdin`.
--
-- Exports:
-- - `StdinReader` to safely display stdin content (striping actions).
-- - `UnsafeStdinReader` to display stdin content as-is.
--
-----------------------------------------------------------------------------
module Xmobar.Plugins.StdinReader (StdinReader(..)) where
import Prelude
import System.Posix.Process
import System.Exit
import System.IO
import System.IO.Error (isEOFError)
import Xmobar.Run.Exec
import Xmobar.X11.Actions (stripActions)
import Control.Concurrent (threadDelay)
import Control.Exception
import Control.Monad (forever)
data StdinReader = StdinReader | UnsafeStdinReader
deriving (Read, Show)
instance Exec StdinReader where
start stdinReader cb = forever $ (cb . escape stdinReader =<< getLine) `catch` handler
where
-- rethrow async exceptions like ThreadKilled, etc.
handler (fromException -> Just e) = throwIO (e :: SomeAsyncException)
-- XMonad.Hooks.DynamicLog.statusBar starts new xmobar on every xmonad
-- reload and the old xmobar is only signalled to exit via the pipe
-- being closed, so we must unconditionally terminate on EOF, otherwise
-- there'd be a pileup of xmobars
handler (fromException -> Just e) | isEOFError e = exitImmediately ExitSuccess
-- any other exception, like "invalid argument (invalid byte sequence)",
-- is logged to both stderr and the bar itself, throttled to avoid
-- excessive CPU usage whenever someone pipes garbage into xmobar, and
-- then discarded without terminating, so a single charset error doesn't
-- break the entire xmobar
handler e = do
let errorMessage = "xmobar: Received exception " <> show e
hPutStrLn stderr errorMessage
cb $ stripActions errorMessage
threadDelay 1000000
escape :: StdinReader -> String -> String
escape StdinReader = stripActions
escape UnsafeStdinReader = id
|
