dist-install/build/System/Posix/Signals.hs

    {-# LINE 1 "libraries/unix/System/Posix/Signals.hsc" #-}
    {-# LANGUAGE CApiFFI, CPP, DeriveDataTypeable, NondecreasingIndentation #-}
    {-# OPTIONS_GHC -fno-cse #-} -- global variables
    {-# LANGUAGE Trustworthy #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  System.Posix.Signals
    -- Copyright   :  (c) The University of Glasgow 2002
    -- License     :  BSD-style (see the file libraries/base/LICENSE)
    --
    -- Maintainer  :  libraries@haskell.org
    -- Stability   :  provisional
    -- Portability :  non-portable (requires POSIX)
    --
    -- POSIX signal support
    --
    -----------------------------------------------------------------------------

    #include "HsUnixConfig.h"

    {-# LINE 22 "libraries/unix/System/Posix/Signals.hsc" #-}

    {-# LINE 24 "libraries/unix/System/Posix/Signals.hsc" #-}

    module System.Posix.Signals (
      -- * The Signal type
      Signal,

      -- * Specific signals
      nullSignal,
      internalAbort, sigABRT,
      realTimeAlarm, sigALRM,
      busError, sigBUS,
      processStatusChanged, sigCHLD,
      continueProcess, sigCONT,
      floatingPointException, sigFPE,
      lostConnection, sigHUP,
      illegalInstruction, sigILL,
      keyboardSignal, sigINT,
      killProcess, sigKILL,
      openEndedPipe, sigPIPE,
      keyboardTermination, sigQUIT,
      segmentationViolation, sigSEGV,
      softwareStop, sigSTOP,
      softwareTermination, sigTERM,
      keyboardStop, sigTSTP,
      backgroundRead, sigTTIN,
      backgroundWrite, sigTTOU,
      userDefinedSignal1, sigUSR1,
      userDefinedSignal2, sigUSR2,

    {-# LINE 52 "libraries/unix/System/Posix/Signals.hsc" #-}
      pollableEvent, sigPOLL,

    {-# LINE 54 "libraries/unix/System/Posix/Signals.hsc" #-}
      profilingTimerExpired, sigPROF,
      badSystemCall, sigSYS,
      breakpointTrap, sigTRAP,
      urgentDataAvailable, sigURG,
      virtualTimerExpired, sigVTALRM,
      cpuTimeLimitExceeded, sigXCPU,
      fileSizeLimitExceeded, sigXFSZ,

      -- * Sending signals
      raiseSignal,
      signalProcess,
      signalProcessGroup,

      -- * Handling signals
      Handler(Default,Ignore,Catch,CatchOnce,CatchInfo,CatchInfoOnce),
      SignalInfo(..), SignalSpecificInfo(..),
      installHandler,

      -- * Signal sets
      SignalSet,
      emptySignalSet, fullSignalSet, reservedSignals,
      addSignal, deleteSignal, inSignalSet,

      -- * The process signal mask
      getSignalMask, setSignalMask, blockSignals, unblockSignals,

      -- * The alarm timer
      scheduleAlarm,

      -- * Waiting for signals
      getPendingSignals,
      awaitSignal,

      -- * The @NOCLDSTOP@ flag
      setStoppedChildFlag, queryStoppedChildFlag,

      -- MISSING FUNCTIONALITY:
      -- sigaction(), (inc. the sigaction structure + flags etc.)
      -- the siginfo structure
      -- sigaltstack()
      -- sighold, sigignore, sigpause, sigrelse, sigset
      -- siginterrupt
      ) where

    import Data.Word
    import Foreign.C
    import Foreign.ForeignPtr
    import Foreign.Marshal
    import Foreign.Ptr
    import Foreign.Storable
    import System.IO.Unsafe (unsafePerformIO)
    import System.Posix.Types
    import System.Posix.Internals
    import System.Posix.Process
    import System.Posix.Process.Internals
    import Data.Dynamic

    #include "rts/Signals.h"

    import GHC.Conc hiding (Signal)

    -- -----------------------------------------------------------------------------
    -- Specific signals

    nullSignal :: Signal
    nullSignal = 0

    sigABRT   :: CInt
    sigABRT   = CONST_SIGABRT
    sigALRM   :: CInt
    sigALRM   = CONST_SIGALRM
    sigBUS    :: CInt
    sigBUS    = CONST_SIGBUS
    sigCHLD   :: CInt
    sigCHLD   = CONST_SIGCHLD
    sigCONT   :: CInt
    sigCONT   = CONST_SIGCONT
    sigFPE    :: CInt
    sigFPE    = CONST_SIGFPE
    sigHUP    :: CInt
    sigHUP    = CONST_SIGHUP
    sigILL    :: CInt
    sigILL    = CONST_SIGILL
    sigINT    :: CInt
    sigINT    = CONST_SIGINT
    sigKILL   :: CInt
    sigKILL   = CONST_SIGKILL
    sigPIPE   :: CInt
    sigPIPE   = CONST_SIGPIPE
    sigQUIT   :: CInt
    sigQUIT   = CONST_SIGQUIT
    sigSEGV   :: CInt
    sigSEGV   = CONST_SIGSEGV
    sigSTOP   :: CInt
    sigSTOP   = CONST_SIGSTOP
    sigTERM   :: CInt
    sigTERM   = CONST_SIGTERM
    sigTSTP   :: CInt
    sigTSTP   = CONST_SIGTSTP
    sigTTIN   :: CInt
    sigTTIN   = CONST_SIGTTIN
    sigTTOU   :: CInt
    sigTTOU   = CONST_SIGTTOU
    sigUSR1   :: CInt
    sigUSR1   = CONST_SIGUSR1
    sigUSR2   :: CInt
    sigUSR2   = CONST_SIGUSR2

    {-# LINE 162 "libraries/unix/System/Posix/Signals.hsc" #-}
    sigPOLL   :: CInt
    sigPOLL   = CONST_SIGPOLL

    {-# LINE 165 "libraries/unix/System/Posix/Signals.hsc" #-}
    sigPROF   :: CInt
    sigPROF   = CONST_SIGPROF
    sigSYS    :: CInt
    sigSYS    = CONST_SIGSYS
    sigTRAP   :: CInt
    sigTRAP   = CONST_SIGTRAP
    sigURG    :: CInt
    sigURG    = CONST_SIGURG
    sigVTALRM :: CInt
    sigVTALRM = CONST_SIGVTALRM
    sigXCPU   :: CInt
    sigXCPU   = CONST_SIGXCPU
    sigXFSZ   :: CInt
    sigXFSZ   = CONST_SIGXFSZ

    internalAbort ::Signal
    internalAbort = sigABRT

    realTimeAlarm :: Signal
    realTimeAlarm = sigALRM

    busError :: Signal
    busError = sigBUS

    processStatusChanged :: Signal
    processStatusChanged = sigCHLD

    continueProcess :: Signal
    continueProcess = sigCONT

    floatingPointException :: Signal
    floatingPointException = sigFPE

    lostConnection :: Signal
    lostConnection = sigHUP

    illegalInstruction :: Signal
    illegalInstruction = sigILL

    keyboardSignal :: Signal
    keyboardSignal = sigINT

    killProcess :: Signal
    killProcess = sigKILL

    openEndedPipe :: Signal
    openEndedPipe = sigPIPE

    keyboardTermination :: Signal
    keyboardTermination = sigQUIT

    segmentationViolation :: Signal
    segmentationViolation = sigSEGV

    softwareStop :: Signal
    softwareStop = sigSTOP

    softwareTermination :: Signal
    softwareTermination = sigTERM

    keyboardStop :: Signal
    keyboardStop = sigTSTP

    backgroundRead :: Signal
    backgroundRead = sigTTIN

    backgroundWrite :: Signal
    backgroundWrite = sigTTOU

    userDefinedSignal1 :: Signal
    userDefinedSignal1 = sigUSR1

    userDefinedSignal2 :: Signal
    userDefinedSignal2 = sigUSR2

    {-# LINE 241 "libraries/unix/System/Posix/Signals.hsc" #-}
    pollableEvent :: Signal
    pollableEvent = sigPOLL

    {-# LINE 244 "libraries/unix/System/Posix/Signals.hsc" #-}

    profilingTimerExpired :: Signal
    profilingTimerExpired = sigPROF

    badSystemCall :: Signal
    badSystemCall = sigSYS

    breakpointTrap :: Signal
    breakpointTrap = sigTRAP

    urgentDataAvailable :: Signal
    urgentDataAvailable = sigURG

    virtualTimerExpired :: Signal
    virtualTimerExpired = sigVTALRM

    cpuTimeLimitExceeded :: Signal
    cpuTimeLimitExceeded = sigXCPU

    fileSizeLimitExceeded :: Signal
    fileSizeLimitExceeded = sigXFSZ

    -- -----------------------------------------------------------------------------
    -- Signal-related functions

    -- | @signalProcess int pid@ calls @kill@ to signal process @pid@
    --   with interrupt signal @int@.
    signalProcess :: Signal -> ProcessID -> IO ()
    signalProcess sig pid
     = throwErrnoIfMinus1_ "signalProcess" (c_kill pid sig)

    foreign import ccall unsafe "kill"
      c_kill :: CPid -> CInt -> IO CInt

    -- | @signalProcessGroup int pgid@ calls @kill@ to signal
    --  all processes in group @pgid@ with interrupt signal @int@.
    signalProcessGroup :: Signal -> ProcessGroupID -> IO ()
    signalProcessGroup sig pgid
      = throwErrnoIfMinus1_ "signalProcessGroup" (c_killpg pgid sig)

    foreign import ccall unsafe "killpg"
      c_killpg :: CPid -> CInt -> IO CInt

    -- | @raiseSignal int@ calls @kill@ to signal the current process
    --   with interrupt signal @int@.
    raiseSignal :: Signal -> IO ()
    raiseSignal sig = throwErrnoIfMinus1_ "raiseSignal" (c_raise sig)

    -- See also note in GHC's rts/RtsUtils.c
    -- This is somewhat fragile because we need to keep the
    -- `#if`-conditional in sync with GHC's runtime.

    {-# LINE 300 "libraries/unix/System/Posix/Signals.hsc" #-}
    foreign import ccall unsafe "raise"
      c_raise :: CInt -> IO CInt

    {-# LINE 303 "libraries/unix/System/Posix/Signals.hsc" #-}

    type Signal = CInt

    -- | The actions to perform when a signal is received.
    data Handler = Default
                 | Ignore
                 -- not yet: | Hold
                 | Catch (IO ())
                 | CatchOnce (IO ())
                 | CatchInfo (SignalInfo -> IO ())     -- ^ @since 2.7.0.0
                 | CatchInfoOnce (SignalInfo -> IO ()) -- ^ @since 2.7.0.0
      deriving (Typeable)

    -- | Information about a received signal (derived from @siginfo_t@).
    --
    -- @since 2.7.0.0
    data SignalInfo = SignalInfo {
          siginfoSignal   :: Signal,
          siginfoError    :: Errno,
          siginfoSpecific :: SignalSpecificInfo
      }

    -- | Information specific to a particular type of signal
    -- (derived from @siginfo_t@).
    --
    -- @since 2.7.0.0
    data SignalSpecificInfo
      = NoSignalSpecificInfo
      | SigChldInfo {
          siginfoPid    :: ProcessID,
          siginfoUid    :: UserID,
          siginfoStatus :: ProcessStatus
        }

    -- | @installHandler int handler iset@ calls @sigaction@ to install an
    --   interrupt handler for signal @int@.  If @handler@ is @Default@,
    --   @SIG_DFL@ is installed; if @handler@ is @Ignore@, @SIG_IGN@ is
    --   installed; if @handler@ is @Catch action@, a handler is installed
    --   which will invoke @action@ in a new thread when (or shortly after) the
    --   signal is received.
    --   If @iset@ is @Just s@, then the @sa_mask@ of the @sigaction@ structure
    --   is set to @s@; otherwise it is cleared.  The previously installed
    --   signal handler for @int@ is returned
    installHandler :: Signal
                   -> Handler
                   -> Maybe SignalSet       -- ^ other signals to block
                   -> IO Handler            -- ^ old handler

    {-# LINE 356 "libraries/unix/System/Posix/Signals.hsc" #-}

    installHandler sig handler _maybe_mask = do
      ensureIOManagerIsRunning  -- for the threaded RTS

      -- if we're setting the action to DFL or IGN, we should do that *first*
      -- if we're setting a handler,
      --   if the previous action was handle, then setHandler is ok
      --   if the previous action was IGN/DFL, then setHandler followed by sig_install
      (old_action, old_handler) <-
        case handler of
          Ignore  -> do
            old_action  <- stg_sig_install sig STG_SIG_IGN nullPtr
            old_handler <- setHandler sig Nothing
            return (old_action, old_handler)

          Default -> do
            old_action  <- stg_sig_install sig STG_SIG_DFL nullPtr
            old_handler <- setHandler sig Nothing
            return (old_action, old_handler)

          _some_kind_of_catch -> do
            -- I don't think it's possible to get CatchOnce right.  If
            -- there's a signal in flight, then we might run the handler
            -- more than once.
            let dyn = toDyn handler
            old_handler <- case handler of
                Catch         action -> setHandler sig (Just (const action,dyn))
                CatchOnce     action -> setHandler sig (Just (const action,dyn))
                CatchInfo     action -> setHandler sig (Just (getinfo action,dyn))
                CatchInfoOnce action -> setHandler sig (Just (getinfo action,dyn))
                _                    -> error "installHandler"

            let action = case handler of
                    Catch _         -> STG_SIG_HAN
                    CatchOnce _     -> STG_SIG_RST
                    CatchInfo _     -> STG_SIG_HAN
                    CatchInfoOnce _ -> STG_SIG_RST
                    _               -> error "installHandler"

            old_action <- stg_sig_install sig action nullPtr
                       -- mask is pointless, so leave it NULL

            return (old_action, old_handler)

      case (old_handler,old_action) of
        (_,       STG_SIG_DFL) -> return $ Default
        (_,       STG_SIG_IGN) -> return $ Ignore
        (Nothing, _)           -> return $ Ignore
        (Just (_,dyn),  _)
            | Just h <- fromDynamic dyn  -> return h
            | Just io <- fromDynamic dyn -> return (Catch io)
            -- handlers put there by the base package have type IO ()
            | otherwise                  -> return Default

    foreign import ccall unsafe
      stg_sig_install
            :: CInt                         -- sig no.
            -> CInt                         -- action code (STG_SIG_HAN etc.)
            -> Ptr CSigset                  -- (in, out) blocked
            -> IO CInt                      -- (ret) old action code

    getinfo :: (SignalInfo -> IO ()) -> ForeignPtr Word8 -> IO ()
    getinfo handler fp_info = do
      si <- unmarshalSigInfo fp_info
      handler si

    unmarshalSigInfo :: ForeignPtr Word8 -> IO SignalInfo
    unmarshalSigInfo fp = do
      withForeignPtr fp $ \p -> do
        sig   <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) p
    {-# LINE 426 "libraries/unix/System/Posix/Signals.hsc" #-}
        errno <- ((\hsc_ptr -> peekByteOff hsc_ptr 4)) p
    {-# LINE 427 "libraries/unix/System/Posix/Signals.hsc" #-}
        extra <- case sig of
                    _ | sig == sigCHLD -> do
                        pid <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) p
    {-# LINE 430 "libraries/unix/System/Posix/Signals.hsc" #-}
                        uid <- ((\hsc_ptr -> peekByteOff hsc_ptr 20)) p
    {-# LINE 431 "libraries/unix/System/Posix/Signals.hsc" #-}
                        wstat <- ((\hsc_ptr -> peekByteOff hsc_ptr 24)) p
    {-# LINE 432 "libraries/unix/System/Posix/Signals.hsc" #-}
                        pstat <- decipherWaitStatus wstat
                        return SigChldInfo { siginfoPid = pid,
                                             siginfoUid = uid,
                                             siginfoStatus = pstat }
                    _ | otherwise ->
                        return NoSignalSpecificInfo
        return
          SignalInfo {
            siginfoSignal = sig,
            siginfoError  = Errno errno,
            siginfoSpecific = extra }

    {-# LINE 445 "libraries/unix/System/Posix/Signals.hsc" #-}

    -- -----------------------------------------------------------------------------
    -- Alarms

    -- | @scheduleAlarm i@ calls @alarm@ to schedule a real time
    --   alarm at least @i@ seconds in the future.
    scheduleAlarm :: Int -> IO Int
    scheduleAlarm secs = do
       r <- c_alarm (fromIntegral secs)
       return (fromIntegral r)

    foreign import ccall unsafe "alarm"
      c_alarm :: CUInt -> IO CUInt

    -- -----------------------------------------------------------------------------
    -- The NOCLDSTOP flag

    foreign import ccall "&nocldstop" nocldstop :: Ptr Int

    -- | Tells the system whether or not to set the @SA_NOCLDSTOP@ flag when
    -- installing new signal handlers.
    setStoppedChildFlag :: Bool -> IO Bool
    setStoppedChildFlag b = do
        rc <- peek nocldstop
        poke nocldstop $ fromEnum (not b)
        return (rc == (0::Int))

    -- | Queries the current state of the stopped child flag.
    queryStoppedChildFlag :: IO Bool
    queryStoppedChildFlag = do
        rc <- peek nocldstop
        return (rc == (0::Int))

    -- -----------------------------------------------------------------------------
    -- Manipulating signal sets

    newtype SignalSet = SignalSet (ForeignPtr CSigset)

    emptySignalSet :: SignalSet
    emptySignalSet = unsafePerformIO $ do
      fp <- mallocForeignPtrBytes sizeof_sigset_t
      throwErrnoIfMinus1_ "emptySignalSet" (withForeignPtr fp $ c_sigemptyset)
      return (SignalSet fp)

    fullSignalSet :: SignalSet
    fullSignalSet = unsafePerformIO $ do
      fp <- mallocForeignPtrBytes sizeof_sigset_t
      throwErrnoIfMinus1_ "fullSignalSet" (withForeignPtr fp $ c_sigfillset)
      return (SignalSet fp)

    -- | A set of signals reserved for use by the implementation.  In GHC, this will normally
    -- include either `sigVTALRM` or `sigALRM`.
    reservedSignals :: SignalSet
    reservedSignals = addSignal rtsTimerSignal emptySignalSet

    foreign import ccall rtsTimerSignal :: CInt

    infixr `addSignal`, `deleteSignal`
    addSignal :: Signal -> SignalSet -> SignalSet
    addSignal sig (SignalSet fp1) = unsafePerformIO $ do
      fp2 <- mallocForeignPtrBytes sizeof_sigset_t
      withForeignPtr fp1 $ \p1 ->
        withForeignPtr fp2 $ \p2 -> do
          copyBytes p2 p1 sizeof_sigset_t
          throwErrnoIfMinus1_ "addSignal" (c_sigaddset p2 sig)
      return (SignalSet fp2)

    deleteSignal :: Signal -> SignalSet -> SignalSet
    deleteSignal sig (SignalSet fp1) = unsafePerformIO $ do
      fp2 <- mallocForeignPtrBytes sizeof_sigset_t
      withForeignPtr fp1 $ \p1 ->
        withForeignPtr fp2 $ \p2 -> do
          copyBytes p2 p1 sizeof_sigset_t
          throwErrnoIfMinus1_ "deleteSignal" (c_sigdelset p2 sig)
      return (SignalSet fp2)

    inSignalSet :: Signal -> SignalSet -> Bool
    inSignalSet sig (SignalSet fp) = unsafePerformIO $
      withForeignPtr fp $ \p -> do
        r <- throwErrnoIfMinus1 "inSignalSet" (c_sigismember p sig)
        return (r /= 0)

    -- | @getSignalMask@ calls @sigprocmask@ to determine the
    --   set of interrupts which are currently being blocked.
    getSignalMask :: IO SignalSet
    getSignalMask = do
      fp <- mallocForeignPtrBytes sizeof_sigset_t
      withForeignPtr fp $ \p ->
        throwErrnoIfMinus1_ "getSignalMask" (c_sigprocmask 0 nullPtr p)
      return (SignalSet fp)

    sigProcMask :: String -> CInt -> SignalSet -> IO ()
    sigProcMask fn how (SignalSet set) =
      withForeignPtr set $ \p_set ->
        throwErrnoIfMinus1_ fn (c_sigprocmask how p_set nullPtr)

    -- | @setSignalMask mask@ calls @sigprocmask@ with
    --   @SIG_SETMASK@ to block all interrupts in @mask@.
    setSignalMask :: SignalSet -> IO ()
    setSignalMask set = sigProcMask "setSignalMask" (CONST_SIG_SETMASK :: CInt) set

    -- | @blockSignals mask@ calls @sigprocmask@ with
    --   @SIG_BLOCK@ to add all interrupts in @mask@ to the
    --  set of blocked interrupts.
    blockSignals :: SignalSet -> IO ()
    blockSignals set = sigProcMask "blockSignals" (CONST_SIG_BLOCK :: CInt) set

    -- | @unblockSignals mask@ calls @sigprocmask@ with
    --   @SIG_UNBLOCK@ to remove all interrupts in @mask@ from the
    --   set of blocked interrupts.
    unblockSignals :: SignalSet -> IO ()
    unblockSignals set = sigProcMask "unblockSignals" (CONST_SIG_UNBLOCK :: CInt) set

    -- | @getPendingSignals@ calls @sigpending@ to obtain
    --   the set of interrupts which have been received but are currently blocked.
    getPendingSignals :: IO SignalSet
    getPendingSignals = do
      fp <- mallocForeignPtrBytes sizeof_sigset_t
      withForeignPtr fp $ \p ->
       throwErrnoIfMinus1_ "getPendingSignals" (c_sigpending p)
      return (SignalSet fp)

    -- | @awaitSignal iset@ suspends execution until an interrupt is received.
    -- If @iset@ is @Just s@, @awaitSignal@ calls @sigsuspend@, installing
    -- @s@ as the new signal mask before suspending execution; otherwise, it
    -- calls @sigsuspend@ with current signal mask. Note that RTS
    -- scheduler signal (either 'virtualTimerExpired' or 'realTimeAlarm')
    -- could cause premature termination of this call. It might be necessary to block that
    -- signal before invocation of @awaitSignal@ with 'blockSignals' 'reservedSignals'.
    --
    -- @awaitSignal@ returns when signal was received and processed by a
    -- signal handler, or if the signal could not be caught. If you have
    -- installed any signal handlers with @installHandler@, it may be wise
    -- to call @yield@ directly after @awaitSignal@ to ensure that the
    -- signal handler runs as promptly as possible.
    awaitSignal :: Maybe SignalSet -> IO ()
    awaitSignal maybe_sigset = do
      fp <- case maybe_sigset of
              Nothing -> do SignalSet fp <- getSignalMask; return fp
              Just (SignalSet fp) -> return fp
      withForeignPtr fp $ \p -> do
      _ <- c_sigsuspend p
      return ()
      -- ignore the return value; according to the docs it can only ever be
      -- (-1) with errno set to EINTR.
      -- XXX My manpage says it can also return EFAULT. And why is ignoring
      -- EINTR the right thing to do?

    foreign import ccall unsafe "sigsuspend"
      c_sigsuspend :: Ptr CSigset -> IO CInt

    {-# LINE 608 "libraries/unix/System/Posix/Signals.hsc" #-}
    foreign import capi unsafe "signal.h sigdelset"
      c_sigdelset   :: Ptr CSigset -> CInt -> IO CInt

    foreign import capi unsafe "signal.h sigfillset"
      c_sigfillset  :: Ptr CSigset -> IO CInt

    foreign import capi unsafe "signal.h sigismember"
      c_sigismember :: Ptr CSigset -> CInt -> IO CInt

    {-# LINE 617 "libraries/unix/System/Posix/Signals.hsc" #-}

    foreign import ccall unsafe "sigpending"
      c_sigpending :: Ptr CSigset -> IO CInt