%  Copyright (C) 2003 David Roundy
%
%  This program is free software; you can redistribute it and/or modify
%  it under the terms of the GNU General Public License as published by
%  the Free Software Foundation; either version 2, or (at your option)
%  any later version.
%
%  This program is distributed in the hope that it will be useful,
%  but WITHOUT ANY WARRANTY; without even the implied warranty of
%  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%  GNU General Public License for more details.
%
%  You should have received a copy of the GNU General Public License
%  along with this program; see the file COPYING.  If not, write to
%  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
%  Boston, MA 02110-1301, USA.


\begin{code}
{-# OPTIONS -fglasgow-exts #-}
module Darcs.SignalHandler ( withSignalsHandled, withSignalsBlocked,
                     ) where

import System.IO.Error ( isUserError, ioeGetErrorString, ioeGetFileName )
import Control.Exception ( catchJust, Exception ( IOException ) )
import System.Exit ( exitWith, ExitCode ( ExitFailure ) )
import Control.Concurrent ( ThreadId, myThreadId )
import Control.Exception ( catchDyn, throwDynTo, block )
import Data.Dynamic ( Typeable )
import Workaround ( installHandler, Handler(..), Signal,
                    sigINT, sigHUP, sigABRT, sigALRM, sigTERM, sigPIPE,
                  )
import System.IO ( hPutStrLn, stderr )
import Control.Monad ( when )
import Darcs.Compat ( stdout_is_a_pipe )
#ifdef WIN32
import CtrlC ( withCtrlCHandler )
#endif
\end{code}

\begin{code}
withSignalsHandled :: IO a -> IO a
newtype SignalException = SignalException Signal deriving (Typeable)

withSignalsHandled job = do
    thid <- myThreadId
    mapM_ (ih thid) [sigINT, sigHUP, sigABRT, sigTERM, sigPIPE]
    catchJust just_usererrors (job' thid `catchSignal` defaults)
              die_with_string
    where defaults s | s == sigINT = ew "Interrupted!"
                     | s ==  sigHUP = ew "HUP"
                     | s ==  sigABRT = ew "ABRT"
                     | s ==  sigTERM = ew "TERM"
                     | s ==  sigPIPE = exitWith $ ExitFailure $ 1
                     | otherwise = ew "Unhandled signal!"
          ew s = do hPutStrLn stderr $ ("withSignalsHandled: " ++ s)
                    exitWith $ ExitFailure $ 1
          die_with_string e | take 6 e == "STDOUT" =
                do is_pipe <- stdout_is_a_pipe
                   when (not is_pipe) $
                        hPutStrLn stderr $ "\ndarcs failed:  "++drop 6 e
                   exitWith $ ExitFailure $ 2
          die_with_string e = do hPutStrLn stderr $ "\ndarcs failed:  "++e
                                 exitWith $ ExitFailure $ 2
#ifdef WIN32
          job' thid =
             withCtrlCHandler (throwDynTo thid $ SignalException sigINT) job
#else
          job' _ = job
#endif

ih :: ThreadId -> Signal -> IO ()
ih thid s =
  do installHandler s (Catch $ throwDynTo thid $ SignalException s) Nothing
     return ()

catchSignal :: IO a -> (Signal -> IO a) -> IO a
catchSignal job handler =
    job `Control.Exception.catchDyn` (\(SignalException sig) -> handler sig)

just_usererrors :: Control.Exception.Exception -> Maybe String
just_usererrors (IOException e) | isUserError e = Just $ ioeGetErrorString e
just_usererrors (IOException e) | ioeGetFileName e == Just "<stdout>"
                                      = Just $ "STDOUT"++ioeGetErrorString e
just_usererrors _ = Nothing
\end{code}

\begin{code}
withSignalsBlocked :: IO () -> IO ()
withSignalsBlocked job = (block job) `catchSignal` couldnt_do
    where couldnt_do s | s == sigINT = oops "interrupt"
                       | s ==  sigHUP = oops "HUP"
                       | s ==  sigABRT = oops "ABRT"
                       | s ==  sigALRM = oops "ALRM"
                       | s ==  sigTERM = oops "TERM"
                       | s ==  sigPIPE = return ()
                       | otherwise = oops "unknown signal"
          oops s = hPutStrLn stderr $ "Couldn't handle " ++ s ++
                   " since darcs was in a sensitive job."
\end{code}
