X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=GHC%2FTopHandler.lhs;h=7bedcfea5df5b44fce2e6b2cc544dc0a4231a328;hb=41e8fba828acbae1751628af50849f5352b27873;hp=d7519efac64ea0ab9cc36f88db9b829e1dd8ce6c;hpb=7de50399a42ee49b0473b7b6eea2b44a2f941a12;p=ghc-base.git diff --git a/GHC/TopHandler.lhs b/GHC/TopHandler.lhs index d7519ef..7bedcfe 100644 --- a/GHC/TopHandler.lhs +++ b/GHC/TopHandler.lhs @@ -1,91 +1,219 @@ --- ----------------------------------------------------------------------------- --- $Id: TopHandler.lhs,v 1.4 2002/02/05 17:32:27 simonmar Exp $ --- --- (c) The University of Glasgow, 2001 +\begin{code} +{-# LANGUAGE CPP + , NoImplicitPrelude + , ForeignFunctionInterface + , MagicHash + , UnboxedTuples + , PatternGuards + #-} +{-# OPTIONS_GHC -fno-warn-unused-imports #-} +{-# OPTIONS_HADDOCK hide #-} + +----------------------------------------------------------------------------- +-- | +-- Module : GHC.TopHandler +-- Copyright : (c) The University of Glasgow, 2001-2002 +-- License : see libraries/base/LICENSE +-- +-- Maintainer : cvs-ghc@haskell.org +-- Stability : internal +-- Portability : non-portable (GHC Extensions) -- --- GHC.TopHandler +-- Support for catching exceptions raised during top-level computations +-- (e.g. @Main.main@, 'Control.Concurrent.forkIO', and foreign exports) -- --- 'Top-level' IO actions want to catch exceptions (e.g., forkIO and --- GHC.Main.mainIO) and report them - topHandler is the exception --- handler they should use for this: - --- make sure we handle errors while reporting the error! --- (e.g. evaluating the string passed to 'error' might generate --- another error, etc.) - --- These functions can't go in GHC.Main, because GHC.Main isn't --- included in HSstd.o (because GHC.Main depends on Main, which --- doesn't exist yet...). +----------------------------------------------------------------------------- -\begin{code} +-- #hide module GHC.TopHandler ( - topHandler, reportStackOverflow, reportError + runMainIO, runIO, runIOFastExit, runNonIO, + topHandler, topHandlerFastExit, + reportStackOverflow, reportError, ) where -import Prelude - -import System.IO +#include "HsBaseConfig.h" + +import Control.Exception +import Data.Maybe +import Data.Dynamic (toDyn) + +import Foreign +import Foreign.C +import GHC.Base +import GHC.Conc hiding (throwTo) +import GHC.Num +import GHC.Real +import GHC.MVar +import GHC.IO +import GHC.IO.Handle.FD +import GHC.IO.Handle +import GHC.IO.Exception +import GHC.Weak +import Data.Typeable +#if defined(mingw32_HOST_OS) +import GHC.ConsoleHandler +#endif -import Foreign.C.String -import Foreign.Ptr -import GHC.IOBase -import GHC.Exception +-- | 'runMainIO' is wrapped around 'Main.main' (or whatever main is +-- called in the program). It catches otherwise uncaught exceptions, +-- and also flushes stdout\/stderr before exiting. +runMainIO :: IO a -> IO a +runMainIO main = + do + main_thread_id <- myThreadId + weak_tid <- mkWeakThreadId main_thread_id + install_interrupt_handler $ do + m <- deRefWeak weak_tid + case m of + Nothing -> return () + Just tid -> throwTo tid (toException UserInterrupt) + a <- main + cleanUp + return a + `catch` + topHandler + +install_interrupt_handler :: IO () -> IO () +#ifdef mingw32_HOST_OS +install_interrupt_handler handler = do + _ <- GHC.ConsoleHandler.installHandler $ + Catch $ \event -> + case event of + ControlC -> handler + Break -> handler + Close -> handler + _ -> return () + return () +#else +#include "rts/Signals.h" +-- specialised version of System.Posix.Signals.installHandler, which +-- isn't available here. +install_interrupt_handler handler = do + let sig = CONST_SIGINT :: CInt + _ <- setHandler sig (Just (const handler, toDyn handler)) + _ <- stg_sig_install sig STG_SIG_RST nullPtr + -- STG_SIG_RST: the second ^C kills us for real, just in case the + -- RTS or program is unresponsive. + return () + +foreign import ccall unsafe + stg_sig_install + :: CInt -- sig no. + -> CInt -- action code (STG_SIG_HAN etc.) + -> Ptr () -- (in, out) blocked + -> IO CInt -- (ret) old action code +#endif -topHandler :: Exception -> IO () -topHandler err = catchException (real_handler err) topHandler +-- make a weak pointer to a ThreadId: holding the weak pointer doesn't +-- keep the thread alive and prevent it from being identified as +-- deadlocked. Vitally important for the main thread. +mkWeakThreadId :: ThreadId -> IO (Weak ThreadId) +mkWeakThreadId t@(ThreadId t#) = IO $ \s -> + case mkWeak# t# t (unsafeCoerce# 0#) s of + (# s1, w #) -> (# s1, Weak w #) + +-- | 'runIO' is wrapped around every @foreign export@ and @foreign +-- import \"wrapper\"@ to mop up any uncaught exceptions. Thus, the +-- result of running 'System.Exit.exitWith' in a foreign-exported +-- function is the same as in the main thread: it terminates the +-- program. +-- +runIO :: IO a -> IO a +runIO main = catch main topHandler + +-- | Like 'runIO', but in the event of an exception that causes an exit, +-- we don't shut down the system cleanly, we just exit. This is +-- useful in some cases, because the safe exit version will give other +-- threads a chance to clean up first, which might shut down the +-- system in a different way. For example, try +-- +-- main = forkIO (runIO (exitWith (ExitFailure 1))) >> threadDelay 10000 +-- +-- This will sometimes exit with "interrupted" and code 0, because the +-- main thread is given a chance to shut down when the child thread calls +-- safeExit. There is a race to shut down between the main and child threads. +-- +runIOFastExit :: IO a -> IO a +runIOFastExit main = catch main topHandlerFastExit + -- NB. this is used by the testsuite driver -real_handler :: Exception -> IO () -real_handler ex = - case ex of - AsyncException StackOverflow -> reportStackOverflow True +-- | The same as 'runIO', but for non-IO computations. Used for +-- wrapping @foreign export@ and @foreign import \"wrapper\"@ when these +-- are used to export Haskell functions with non-IO types. +-- +runNonIO :: a -> IO a +runNonIO a = catch (a `seq` return a) topHandler - -- only the main thread gets ExitException exceptions - ExitException ExitSuccess -> shutdownHaskellAndExit 0 - ExitException (ExitFailure n) -> shutdownHaskellAndExit n +topHandler :: SomeException -> IO a +topHandler err = catch (real_handler safeExit err) topHandler - Deadlock -> reportError True - "no threads to run: infinite loop or deadlock?" - - ErrorCall s -> reportError True s - other -> reportError True (showsPrec 0 other "\n") +topHandlerFastExit :: SomeException -> IO a +topHandlerFastExit err = + catchException (real_handler fastExit err) topHandlerFastExit --- NOTE: shutdownHaskellAndExit must be called "safe", because it *can* --- re-enter Haskell land through finalizers. -foreign import ccall "shutdownHaskellAndExit" - shutdownHaskellAndExit :: Int -> IO () - -reportStackOverflow :: Bool -> IO () -reportStackOverflow bombOut = do - (hFlush stdout) `catchException` (\ _ -> return ()) - callStackOverflowHook - if bombOut then - stg_exit 2 - else - return () - -reportError :: Bool -> String -> IO () -reportError bombOut str = do - (hFlush stdout) `catchException` (\ _ -> return ()) - withCStringLen str $ \(cstr,len) -> do - writeErrString errorHdrHook cstr len - if bombOut - then stg_exit 1 - else return () - -#ifndef ILX -foreign label "ErrorHdrHook" errorHdrHook :: Ptr () +-- Make sure we handle errors while reporting the error! +-- (e.g. evaluating the string passed to 'error' might generate +-- another error, etc.) +-- +real_handler :: (Int -> IO a) -> SomeException -> IO a +real_handler exit se@(SomeException exn) = + cleanUp >> + case cast exn of + Just StackOverflow -> do + reportStackOverflow + exit 2 + + Just UserInterrupt -> exitInterrupted + + _ -> case cast exn of + -- only the main thread gets ExitException exceptions + Just ExitSuccess -> exit 0 + Just (ExitFailure n) -> exit n + + -- EPIPE errors received for stdout are ignored (#2699) + _ -> case cast exn of + Just IOError{ ioe_type = ResourceVanished, + ioe_errno = Just ioe, + ioe_handle = Just hdl } + | Errno ioe == ePIPE, hdl == stdout -> exit 0 + _ -> do reportError se + exit 1 + + +-- try to flush stdout/stderr, but don't worry if we fail +-- (these handles might have errors, and we don't want to go into +-- an infinite loop). +cleanUp :: IO () +cleanUp = do + hFlush stdout `catchAny` \_ -> return () + hFlush stderr `catchAny` \_ -> return () + +-- we have to use unsafeCoerce# to get the 'IO a' result type, since the +-- compiler doesn't let us declare that as the result type of a foreign export. +safeExit :: Int -> IO a +safeExit r = unsafeCoerce# (shutdownHaskellAndExit $ fromIntegral r) + +exitInterrupted :: IO a +exitInterrupted = +#ifdef mingw32_HOST_OS + safeExit 252 #else -foreign import "ErrorHdrHook" errorHdrHook :: Ptr () + -- we must exit via the default action for SIGINT, so that the + -- parent of this process can take appropriate action (see #2301) + unsafeCoerce# (shutdownHaskellAndSignal CONST_SIGINT) + +foreign import ccall "shutdownHaskellAndSignal" + shutdownHaskellAndSignal :: CInt -> IO () #endif -foreign import ccall "writeErrString__" unsafe - writeErrString :: Ptr () -> CString -> Int -> IO () +-- NOTE: shutdownHaskellAndExit must be called "safe", because it *can* +-- re-enter Haskell land through finalizers. +foreign import ccall "Rts.h shutdownHaskellAndExit" + shutdownHaskellAndExit :: CInt -> IO () --- SUP: Are the hooks allowed to re-enter Haskell land? If so, remove --- the unsafe below. -foreign import ccall "stackOverflow" unsafe - callStackOverflowHook :: IO () +fastExit :: Int -> IO a +fastExit r = unsafeCoerce# (stg_exit (fromIntegral r)) -foreign import ccall "stg_exit" unsafe - stg_exit :: Int -> IO () +foreign import ccall "Rts.h stg_exit" + stg_exit :: CInt -> IO () \end{code}