    {-# INCLUDE "HsUnix.h" #-}
    {-# LINE 1 "System/Posix/Process.hsc" #-}
    {-# LANGUAGE ForeignFunctionInterface #-}
    {-# LINE 2 "System/Posix/Process.hsc" #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  System.Posix.Process
    -- 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 process support.  See also the System.Cmd and System.Process
    -- modules in the process package.
    --
    -----------------------------------------------------------------------------

    module System.Posix.Process (
        -- * Processes

        -- ** Forking and executing

    {-# LINE 22 "System/Posix/Process.hsc" #-}
        forkProcess,

    {-# LINE 24 "System/Posix/Process.hsc" #-}
        executeFile,

        -- ** Exiting
        exitImmediately,

        -- ** Process environment
        getProcessID,
        getParentProcessID,
        getProcessGroupID,

        -- ** Process groups
        createProcessGroup,
        joinProcessGroup,
        setProcessGroupID,

        -- ** Sessions
        createSession,

        -- ** Process times
        ProcessTimes(..),
        getProcessTimes,

        -- ** Scheduling priority
        nice,
        getProcessPriority,
        getProcessGroupPriority,
        getUserPriority,
        setProcessPriority,
        setProcessGroupPriority,
        setUserPriority,

        -- ** Process status
        ProcessStatus(..),
        getProcessStatus,
        getAnyProcessStatus,
        getGroupProcessStatus,

     ) where

    {-# LINE 64 "System/Posix/Process.hsc" #-}

    import Foreign.C.Error
    import Foreign.C.String ( CString, withCString )
    import Foreign.C.Types ( CInt, CClock )
    import Foreign.Marshal.Alloc ( alloca, allocaBytes )
    import Foreign.Marshal.Array ( withArray0 )
    import Foreign.Marshal.Utils ( withMany )
    import Foreign.Ptr ( Ptr, nullPtr )
    import Foreign.StablePtr ( StablePtr, newStablePtr, freeStablePtr )
    import Foreign.Storable ( Storable(..) )
    import System.IO
    import System.Exit
    import System.Posix.Error
    import System.Posix.Process.Internals
    import System.Posix.Types
    import Control.Monad

    {-# LINE 82 "System/Posix/Process.hsc" #-}
    import GHC.TopHandler	( runIO )

    {-# LINE 84 "System/Posix/Process.hsc" #-}

    {-# LINE 88 "System/Posix/Process.hsc" #-}

    -- -----------------------------------------------------------------------------
    -- Process environment

    -- | 'getProcessID' calls @getpid@ to obtain the 'ProcessID' for
    --   the current process.
    getProcessID :: IO ProcessID
    getProcessID = c_getpid

    foreign import ccall unsafe "getpid"
       c_getpid :: IO CPid

    -- | 'getProcessID' calls @getppid@ to obtain the 'ProcessID' for
    --   the parent of the current process.
    getParentProcessID :: IO ProcessID
    getParentProcessID = c_getppid

    foreign import ccall unsafe "getppid"
      c_getppid :: IO CPid

    -- | 'getProcessGroupID' calls @getpgrp@ to obtain the
    --   'ProcessGroupID' for the current process.
    getProcessGroupID :: IO ProcessGroupID
    getProcessGroupID = c_getpgrp

    foreign import ccall unsafe "getpgrp"
      c_getpgrp :: IO CPid

    -- | @'createProcessGroup' pid@ calls @setpgid@ to make
    --   process @pid@ a new process group leader.
    createProcessGroup :: ProcessID -> IO ProcessGroupID
    createProcessGroup pid = do
      throwErrnoIfMinus1_ "createProcessGroup" (c_setpgid pid 0)
      return pid

    -- | @'joinProcessGroup' pgid@ calls @setpgid@ to set the
    --   'ProcessGroupID' of the current process to @pgid@.
    joinProcessGroup :: ProcessGroupID -> IO ()
    joinProcessGroup pgid =
      throwErrnoIfMinus1_ "joinProcessGroup" (c_setpgid 0 pgid)

    -- | @'setProcessGroupID' pid pgid@ calls @setpgid@ to set the
    --   'ProcessGroupID' for process @pid@ to @pgid@.
    setProcessGroupID :: ProcessID -> ProcessGroupID -> IO ()
    setProcessGroupID pid pgid =
      throwErrnoIfMinus1_ "setProcessGroupID" (c_setpgid pid pgid)

    foreign import ccall unsafe "setpgid"
      c_setpgid :: CPid -> CPid -> IO CInt

    -- | 'createSession' calls @setsid@ to create a new session
    --   with the current process as session leader.
    createSession :: IO ProcessGroupID
    createSession = throwErrnoIfMinus1 "createSession" c_setsid

    foreign import ccall unsafe "setsid"
      c_setsid :: IO CPid

    -- -----------------------------------------------------------------------------
    -- Process times

    -- All times in clock ticks (see getClockTick)

    data ProcessTimes
      = ProcessTimes { elapsedTime     :: ClockTick
      		 , userTime        :: ClockTick
    		 , systemTime      :: ClockTick
    		 , childUserTime   :: ClockTick
    		 , childSystemTime :: ClockTick
    		 }

    -- | 'getProcessTimes' calls @times@ to obtain time-accounting
    --   information for the current process and its children.
    getProcessTimes :: IO ProcessTimes
    getProcessTimes = do
       allocaBytes (16) $ \p_tms -> do
    {-# LINE 164 "System/Posix/Process.hsc" #-}
         elapsed <- throwErrnoIfMinus1 "getProcessTimes" (c_times p_tms)
         ut  <- ((\hsc_ptr -> peekByteOff hsc_ptr 0))  p_tms
    {-# LINE 166 "System/Posix/Process.hsc" #-}
         st  <- ((\hsc_ptr -> peekByteOff hsc_ptr 4))  p_tms
    {-# LINE 167 "System/Posix/Process.hsc" #-}
         cut <- ((\hsc_ptr -> peekByteOff hsc_ptr 8)) p_tms
    {-# LINE 168 "System/Posix/Process.hsc" #-}
         cst <- ((\hsc_ptr -> peekByteOff hsc_ptr 12)) p_tms
    {-# LINE 169 "System/Posix/Process.hsc" #-}
         return (ProcessTimes{ elapsedTime     = elapsed,
    	 		   userTime        = ut,
    	 		   systemTime      = st,
    	 		   childUserTime   = cut,
    	 		   childSystemTime = cst
    			  })

    type CTms = ()

    foreign import ccall unsafe "times"
      c_times :: Ptr CTms -> IO CClock

    -- -----------------------------------------------------------------------------
    -- Process scheduling priority

    nice :: Int -> IO ()
    nice prio = do
      resetErrno
      res <- c_nice (fromIntegral prio)
      when (res == -1) $ do
        err <- getErrno
        when (err /= eOK) (throwErrno "nice")

    foreign import ccall unsafe "nice"
      c_nice :: CInt -> IO CInt

    getProcessPriority      :: ProcessID      -> IO Int
    getProcessGroupPriority :: ProcessGroupID -> IO Int
    getUserPriority         :: UserID         -> IO Int

    getProcessPriority pid = do
      r <- throwErrnoIfMinus1 "getProcessPriority" $
             c_getpriority (0) (fromIntegral pid)
    {-# LINE 202 "System/Posix/Process.hsc" #-}
      return (fromIntegral r)

    getProcessGroupPriority pid = do
      r <- throwErrnoIfMinus1 "getProcessPriority" $
             c_getpriority (1) (fromIntegral pid)
    {-# LINE 207 "System/Posix/Process.hsc" #-}
      return (fromIntegral r)

    getUserPriority uid = do
      r <- throwErrnoIfMinus1 "getUserPriority" $
             c_getpriority (2) (fromIntegral uid)
    {-# LINE 212 "System/Posix/Process.hsc" #-}
      return (fromIntegral r)

    foreign import ccall unsafe "getpriority"
      c_getpriority :: CInt -> CInt -> IO CInt

    setProcessPriority      :: ProcessID      -> Int -> IO ()
    setProcessGroupPriority :: ProcessGroupID -> Int -> IO ()
    setUserPriority         :: UserID         -> Int -> IO ()

    setProcessPriority pid val =
      throwErrnoIfMinus1_ "setProcessPriority" $
        c_setpriority (0) (fromIntegral pid) (fromIntegral val)
    {-# LINE 224 "System/Posix/Process.hsc" #-}

    setProcessGroupPriority pid val =
      throwErrnoIfMinus1_ "setProcessPriority" $
        c_setpriority (1) (fromIntegral pid) (fromIntegral val)
    {-# LINE 228 "System/Posix/Process.hsc" #-}

    setUserPriority uid val =
      throwErrnoIfMinus1_ "setUserPriority" $
        c_setpriority (2) (fromIntegral uid) (fromIntegral val)
    {-# LINE 232 "System/Posix/Process.hsc" #-}

    foreign import ccall unsafe "setpriority"
      c_setpriority :: CInt -> CInt -> CInt -> IO CInt

    -- -----------------------------------------------------------------------------
    -- Forking, execution

    {-# LINE 240 "System/Posix/Process.hsc" #-}
    {- | 'forkProcess' corresponds to the POSIX @fork@ system call.
    The 'IO' action passed as an argument is executed in the child process; no other
    threads will be copied to the child process.
    On success, 'forkProcess' returns the child's 'ProcessID' to the parent process;
    in case of an error, an exception is thrown.

    'forkProcess' comes with a giant warning: since any other running
    threads are not copied into the child process, it's easy to go wrong:
    e.g. by accessing some shared resource that was held by another thread
    in the parent.  Another example is the I\/O manager thread: since the
    I\/O manager isn't running in the child, attempting to do any
    Handle-based I\/O will deadlock.

    Using 'forkProcess' in order to do 'executeFile' is likely to work.
    Anything else: you're on your own.
    -}

    forkProcess :: IO () -> IO ProcessID
    forkProcess action = do
      stable <- newStablePtr (runIO action)
      pid <- throwErrnoIfMinus1 "forkProcess" (forkProcessPrim stable)
      freeStablePtr stable
      return $ fromIntegral pid

    foreign import ccall "forkProcess" forkProcessPrim :: StablePtr (IO ()) -> IO CPid

    {-# LINE 266 "System/Posix/Process.hsc" #-}

    -- | @'executeFile' cmd args env@ calls one of the
    --   @execv*@ family, depending on whether or not the current
    --   PATH is to be searched for the command, and whether or not an
    --   environment is provided to supersede the process's current
    --   environment.  The basename (leading directory names suppressed) of
    --   the command is passed to @execv*@ as @arg[0]@;
    --   the argument list passed to 'executeFile' therefore
    --   begins with @arg[1]@.
    executeFile :: FilePath			    -- ^ Command
                -> Bool			    -- ^ Search PATH?
                -> [String]			    -- ^ Arguments
                -> Maybe [(String, String)]	    -- ^ Environment
                -> IO ()
    executeFile path search args Nothing = do
      withCString path $ \s ->
        withMany withCString (path:args) $ \cstrs ->
          withArray0 nullPtr cstrs $ \arr -> do
    	pPrPr_disableITimers
    	if search
    	   then throwErrnoPathIfMinus1_ "executeFile" path (c_execvp s arr)
    	   else throwErrnoPathIfMinus1_ "executeFile" path (c_execv s arr)

    executeFile path search args (Just env) = do
      withCString path $ \s ->
        withMany withCString (path:args) $ \cstrs ->
          withArray0 nullPtr cstrs $ \arg_arr ->
        let env' = map (\ (name, val) -> name ++ ('=' : val)) env in
        withMany withCString env' $ \cenv ->
          withArray0 nullPtr cenv $ \env_arr -> do
    	pPrPr_disableITimers
    	if search
    	   then throwErrnoPathIfMinus1_ "executeFile" path
    		   (c_execvpe s arg_arr env_arr)
    	   else throwErrnoPathIfMinus1_ "executeFile" path
    		   (c_execve s arg_arr env_arr)

    foreign import ccall unsafe "execvp"
      c_execvp :: CString -> Ptr CString -> IO CInt

    foreign import ccall unsafe "execv"
      c_execv :: CString -> Ptr CString -> IO CInt

    foreign import ccall unsafe "execve"
      c_execve :: CString -> Ptr CString -> Ptr CString -> IO CInt

    -- -----------------------------------------------------------------------------
    -- Waiting for process termination

    -- | @'getProcessStatus' blk stopped pid@ calls @waitpid@, returning
    --   @'Just' tc@, the 'ProcessStatus' for process @pid@ if it is
    --   available, 'Nothing' otherwise.  If @blk@ is 'False', then
    --   @WNOHANG@ is set in the options for @waitpid@, otherwise not.
    --   If @stopped@ is 'True', then @WUNTRACED@ is set in the
    --   options for @waitpid@, otherwise not.
    getProcessStatus :: Bool -> Bool -> ProcessID -> IO (Maybe ProcessStatus)
    getProcessStatus block stopped pid =
      alloca $ \wstatp -> do
        pid' <- throwErrnoIfMinus1Retry "getProcessStatus"
    		(c_waitpid pid wstatp (waitOptions block stopped))
        case pid' of
          0  -> return Nothing
          _  -> do ps <- readWaitStatus wstatp
    	       return (Just ps)

    -- safe, because this call might block
    foreign import ccall safe "waitpid"
      c_waitpid :: CPid -> Ptr CInt -> CInt -> IO CPid

    -- | @'getGroupProcessStatus' blk stopped pgid@ calls @waitpid@,
    --   returning @'Just' (pid, tc)@, the 'ProcessID' and
    --   'ProcessStatus' for any process in group @pgid@ if one is
    --   available, 'Nothing' otherwise.  If @blk@ is 'False', then
    --   @WNOHANG@ is set in the options for @waitpid@, otherwise not.
    --   If @stopped@ is 'True', then @WUNTRACED@ is set in the
    --   options for @waitpid@, otherwise not.
    getGroupProcessStatus :: Bool
                          -> Bool
                          -> ProcessGroupID
                          -> IO (Maybe (ProcessID, ProcessStatus))
    getGroupProcessStatus block stopped pgid =
      alloca $ \wstatp -> do
        pid <- throwErrnoIfMinus1Retry "getGroupProcessStatus"
    		(c_waitpid (-pgid) wstatp (waitOptions block stopped))
        case pid of
          0  -> return Nothing
          _  -> do ps <- readWaitStatus wstatp
    	       return (Just (pid, ps))
    -- | @'getAnyProcessStatus' blk stopped@ calls @waitpid@, returning
    --   @'Just' (pid, tc)@, the 'ProcessID' and 'ProcessStatus' for any
    --   child process if one is available, 'Nothing' otherwise.  If
    --   @blk@ is 'False', then @WNOHANG@ is set in the options for
    --   @waitpid@, otherwise not.  If @stopped@ is 'True', then
    --   @WUNTRACED@ is set in the options for @waitpid@, otherwise not.
    getAnyProcessStatus :: Bool -> Bool -> IO (Maybe (ProcessID, ProcessStatus))
    getAnyProcessStatus block stopped = getGroupProcessStatus block stopped 1

    waitOptions :: Bool -> Bool -> CInt
    --             block   stopped
    waitOptions False False = (1)
    {-# LINE 366 "System/Posix/Process.hsc" #-}
    waitOptions False True  = (3)
    {-# LINE 367 "System/Posix/Process.hsc" #-}
    waitOptions True  False = 0
    waitOptions True  True  = (2)
    {-# LINE 369 "System/Posix/Process.hsc" #-}

    -- Turn a (ptr to a) wait status into a ProcessStatus

    readWaitStatus :: Ptr CInt -> IO ProcessStatus
    readWaitStatus wstatp = do
      wstat <- peek wstatp
      decipherWaitStatus wstat

    -- -----------------------------------------------------------------------------
    -- Exiting

    -- | @'exitImmediately' status@ calls @_exit@ to terminate the process
    --   with the indicated exit @status@.
    --   The operation never returns.
    exitImmediately :: ExitCode -> IO ()
    exitImmediately exitcode = c_exit (exitcode2Int exitcode)
      where
        exitcode2Int ExitSuccess = 0
        exitcode2Int (ExitFailure n) = fromIntegral n

    foreign import ccall unsafe "exit"
      c_exit :: CInt -> IO ()

    -- -----------------------------------------------------------------------------