{-# LANGUAGE CPP, ForeignFunctionInterface #-} #if __GLASGOW_HASKELL__ >= 701 -- not available prior to 7.1 {-# LANGUAGE InterruptibleFFI #-} #endif ----------------------------------------------------------------------------- -- | -- Module : System.Process -- Copyright : (c) The University of Glasgow 2004-2008 -- License : BSD-style (see the file libraries/base/LICENSE) -- -- Maintainer : libraries@haskell.org -- Stability : experimental -- Portability : non-portable (requires concurrency) -- -- Operations for creating and interacting with sub-processes. -- ----------------------------------------------------------------------------- -- ToDo: -- * Flag to control whether exiting the parent also kills the child. {- NOTES on createPipe: createPipe is no longer exported, because of the following problems: - it wasn't used to implement runInteractiveProcess on Unix, because the file descriptors for the unused ends of the pipe need to be closed in the child process. - on Windows, a special version of createPipe is needed that sets the inheritance flags correctly on the ends of the pipe (see mkAnonPipe below). -} module System.Process ( #ifndef __HUGS__ -- * Running sub-processes createProcess, shell, proc, CreateProcess(..), CmdSpec(..), StdStream(..), ProcessHandle, -- ** Specific variants of createProcess runCommand, runProcess, runInteractiveCommand, runInteractiveProcess, readProcess, readProcessWithExitCode, #endif system, rawSystem, showCommandForUser, #ifndef __HUGS__ -- * Process completion waitForProcess, getProcessExitCode, terminateProcess, interruptProcessGroupOf, #endif ) where import Prelude hiding (mapM) #ifndef __HUGS__ import System.Process.Internals import System.IO.Error import qualified Control.Exception as C import Control.Concurrent import Control.Monad import Foreign import Foreign.C import System.IO import Data.Maybe #endif import System.Exit ( ExitCode(..) ) #ifdef __GLASGOW_HASKELL__ #if __GLASGOW_HASKELL__ >= 611 import GHC.IO.Exception ( ioException, IOErrorType(..) ) #else import GHC.IOBase ( ioException, IOErrorType(..) ) #endif #if defined(mingw32_HOST_OS) import System.Win32.Process (getProcessId) import System.Win32.Console (generateConsoleCtrlEvent, cTRL_BREAK_EVENT) #else import System.Posix.Signals #endif #endif #ifdef __HUGS__ import Hugs.System #endif #ifdef __NHC__ import System (system) #endif #ifndef __HUGS__ -- ---------------------------------------------------------------------------- -- runCommand {- | Runs a command using the shell. -} runCommand :: String -> IO ProcessHandle runCommand string = do (_,_,_,ph) <- runGenProcess_ "runCommand" (shell string) Nothing Nothing return ph -- ---------------------------------------------------------------------------- -- runProcess {- | Runs a raw command, optionally specifying 'Handle's from which to take the @stdin@, @stdout@ and @stderr@ channels for the new process (otherwise these handles are inherited from the current process). Any 'Handle's passed to 'runProcess' are placed immediately in the closed state. Note: consider using the more general 'createProcess' instead of 'runProcess'. -} runProcess :: FilePath -- ^ Filename of the executable -> [String] -- ^ Arguments to pass to the executable -> Maybe FilePath -- ^ Optional path to the working directory -> Maybe [(String,String)] -- ^ Optional environment (otherwise inherit) -> Maybe Handle -- ^ Handle to use for @stdin@ (Nothing => use existing @stdin@) -> Maybe Handle -- ^ Handle to use for @stdout@ (Nothing => use existing @stdout@) -> Maybe Handle -- ^ Handle to use for @stderr@ (Nothing => use existing @stderr@) -> IO ProcessHandle runProcess cmd args mb_cwd mb_env mb_stdin mb_stdout mb_stderr = do (_,_,_,ph) <- runGenProcess_ "runProcess" (proc cmd args){ cwd = mb_cwd, env = mb_env, std_in = mbToStd mb_stdin, std_out = mbToStd mb_stdout, std_err = mbToStd mb_stderr } Nothing Nothing maybeClose mb_stdin maybeClose mb_stdout maybeClose mb_stderr return ph where maybeClose :: Maybe Handle -> IO () maybeClose (Just hdl) | hdl /= stdin && hdl /= stdout && hdl /= stderr = hClose hdl maybeClose _ = return () mbToStd :: Maybe Handle -> StdStream mbToStd Nothing = Inherit mbToStd (Just hdl) = UseHandle hdl -- ---------------------------------------------------------------------------- -- createProcess -- | Construct a 'CreateProcess' record for passing to 'createProcess', -- representing a raw command with arguments. proc :: FilePath -> [String] -> CreateProcess proc cmd args = CreateProcess { cmdspec = RawCommand cmd args, cwd = Nothing, env = Nothing, std_in = Inherit, std_out = Inherit, std_err = Inherit, close_fds = False, create_group = False} -- | Construct a 'CreateProcess' record for passing to 'createProcess', -- representing a command to be passed to the shell. shell :: String -> CreateProcess shell str = CreateProcess { cmdspec = ShellCommand str, cwd = Nothing, env = Nothing, std_in = Inherit, std_out = Inherit, std_err = Inherit, close_fds = False, create_group = False} {- | This is the most general way to spawn an external process. The process can be a command line to be executed by a shell or a raw command with a list of arguments. The stdin, stdout, and stderr streams of the new process may individually be attached to new pipes, to existing 'Handle's, or just inherited from the parent (the default.) The details of how to create the process are passed in the 'CreateProcess' record. To make it easier to construct a 'CreateProcess', the functions 'proc' and 'shell' are supplied that fill in the fields with default values which can be overriden as needed. 'createProcess' returns @(mb_stdin_hdl, mb_stdout_hdl, mb_stderr_hdl, p)@, where * if @std_in == CreatePipe@, then @mb_stdin_hdl@ will be @Just h@, where @h@ is the write end of the pipe connected to the child process's @stdin@. * otherwise, @mb_stdin_hdl == Nothing@ Similarly for @mb_stdout_hdl@ and @mb_stderr_hdl@. For example, to execute a simple @ls@ command: > r <- createProcess (proc "ls" []) To create a pipe from which to read the output of @ls@: > (_, Just hout, _, _) <- > createProcess (proc "ls" []){ std_out = CreatePipe } To also set the directory in which to run @ls@: > (_, Just hout, _, _) <- > createProcess (proc "ls" []){ cwd = Just "\home\bob", > std_out = CreatePipe } -} createProcess :: CreateProcess -> IO (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle) createProcess cp = do r <- runGenProcess_ "createProcess" cp Nothing Nothing maybeCloseStd (std_in cp) maybeCloseStd (std_out cp) maybeCloseStd (std_err cp) return r where maybeCloseStd :: StdStream -> IO () maybeCloseStd (UseHandle hdl) | hdl /= stdin && hdl /= stdout && hdl /= stderr = hClose hdl maybeCloseStd _ = return () -- ---------------------------------------------------------------------------- -- runInteractiveCommand {- | Runs a command using the shell, and returns 'Handle's that may be used to communicate with the process via its @stdin@, @stdout@, and @stderr@ respectively. The 'Handle's are initially in binary mode; if you need them to be in text mode then use 'hSetBinaryMode'. -} runInteractiveCommand :: String -> IO (Handle,Handle,Handle,ProcessHandle) runInteractiveCommand string = runInteractiveProcess1 "runInteractiveCommand" (shell string) -- ---------------------------------------------------------------------------- -- runInteractiveProcess {- | Runs a raw command, and returns 'Handle's that may be used to communicate with the process via its @stdin@, @stdout@ and @stderr@ respectively. For example, to start a process and feed a string to its stdin: > (inp,out,err,pid) <- runInteractiveProcess "..." > forkIO (hPutStr inp str) The 'Handle's are initially in binary mode; if you need them to be in text mode then use 'hSetBinaryMode'. -} runInteractiveProcess :: FilePath -- ^ Filename of the executable -> [String] -- ^ Arguments to pass to the executable -> Maybe FilePath -- ^ Optional path to the working directory -> Maybe [(String,String)] -- ^ Optional environment (otherwise inherit) -> IO (Handle,Handle,Handle,ProcessHandle) runInteractiveProcess cmd args mb_cwd mb_env = do runInteractiveProcess1 "runInteractiveProcess" (proc cmd args){ cwd = mb_cwd, env = mb_env } runInteractiveProcess1 :: String -> CreateProcess -> IO (Handle,Handle,Handle,ProcessHandle) runInteractiveProcess1 fun cmd = do (mb_in, mb_out, mb_err, p) <- runGenProcess_ fun cmd{ std_in = CreatePipe, std_out = CreatePipe, std_err = CreatePipe } Nothing Nothing return (fromJust mb_in, fromJust mb_out, fromJust mb_err, p) -- ---------------------------------------------------------------------------- -- waitForProcess {- | Waits for the specified process to terminate, and returns its exit code. GHC Note: in order to call @waitForProcess@ without blocking all the other threads in the system, you must compile the program with @-threaded@. -} waitForProcess :: ProcessHandle -> IO ExitCode waitForProcess ph = do p_ <- withProcessHandle ph $ \p_ -> return (p_,p_) case p_ of ClosedHandle e -> return e OpenHandle h -> do -- don't hold the MVar while we call c_waitForProcess... -- (XXX but there's a small race window here during which another -- thread could close the handle or call waitForProcess) alloca $ \pret -> do throwErrnoIfMinus1Retry_ "waitForProcess" (c_waitForProcess h pret) withProcessHandle ph $ \p_' -> case p_' of ClosedHandle e -> return (p_',e) OpenHandle ph' -> do closePHANDLE ph' code <- peek pret let e = if (code == 0) then ExitSuccess else (ExitFailure (fromIntegral code)) return (ClosedHandle e, e) -- ----------------------------------------------------------------------------- -- -- | readProcess forks an external process, reads its standard output -- strictly, blocking until the process terminates, and returns the output -- string. -- -- Output is returned strictly, so this is not suitable for -- interactive applications. -- -- Users of this function should compile with @-threaded@ if they -- want other Haskell threads to keep running while waiting on -- the result of readProcess. -- -- > > readProcess "date" [] [] -- > "Thu Feb 7 10:03:39 PST 2008\n" -- -- The arguments are: -- -- * The command to run, which must be in the $PATH, or an absolute path -- -- * A list of separate command line arguments to the program -- -- * A string to pass on the standard input to the program. -- readProcess :: FilePath -- ^ command to run -> [String] -- ^ any arguments -> String -- ^ standard input -> IO String -- ^ stdout readProcess cmd args input = do (Just inh, Just outh, _, pid) <- createProcess (proc cmd args){ std_in = CreatePipe, std_out = CreatePipe, std_err = Inherit } -- fork off a thread to start consuming the output output <- hGetContents outh outMVar <- newEmptyMVar _ <- forkIO $ C.evaluate (length output) >> putMVar outMVar () -- now write and flush any input when (not (null input)) $ do hPutStr inh input; hFlush inh hClose inh -- done with stdin -- wait on the output takeMVar outMVar hClose outh -- wait on the process ex <- waitForProcess pid case ex of ExitSuccess -> return output ExitFailure r -> ioError (mkIOError OtherError ("readProcess: " ++ cmd ++ ' ':unwords (map show args) ++ " (exit " ++ show r ++ ")") Nothing Nothing) {- | readProcessWithExitCode creates an external process, reads its standard output and standard error strictly, waits until the process terminates, and then returns the 'ExitCode' of the process, the standard output, and the standard error. 'readProcess' and 'readProcessWithExitCode' are fairly simple wrappers around 'createProcess'. Constructing variants of these functions is quite easy: follow the link to the source code to see how 'readProcess' is implemented. -} readProcessWithExitCode :: FilePath -- ^ command to run -> [String] -- ^ any arguments -> String -- ^ standard input -> IO (ExitCode,String,String) -- ^ exitcode, stdout, stderr readProcessWithExitCode cmd args input = do (Just inh, Just outh, Just errh, pid) <- createProcess (proc cmd args){ std_in = CreatePipe, std_out = CreatePipe, std_err = CreatePipe } outMVar <- newEmptyMVar -- fork off a thread to start consuming stdout out <- hGetContents outh _ <- forkIO $ C.evaluate (length out) >> putMVar outMVar () -- fork off a thread to start consuming stderr err <- hGetContents errh _ <- forkIO $ C.evaluate (length err) >> putMVar outMVar () -- now write and flush any input when (not (null input)) $ do hPutStr inh input; hFlush inh hClose inh -- done with stdin -- wait on the output takeMVar outMVar takeMVar outMVar hClose outh hClose errh -- wait on the process ex <- waitForProcess pid return (ex, out, err) #endif /* !__HUGS__ */ -- --------------------------------------------------------------------------- -- system {-| Computation @system cmd@ returns the exit code produced when the operating system runs the shell command @cmd@. This computation may fail with * @PermissionDenied@: The process has insufficient privileges to perform the operation. * @ResourceExhausted@: Insufficient resources are available to perform the operation. * @UnsupportedOperation@: The implementation does not support system calls. On Windows, 'system' passes the command to the Windows command interpreter (@CMD.EXE@ or @COMMAND.COM@), hence Unixy shell tricks will not work. -} #ifdef __GLASGOW_HASKELL__ system :: String -> IO ExitCode system "" = ioException (ioeSetErrorString (mkIOError InvalidArgument "system" Nothing Nothing) "null command") system str = syncProcess "system" (shell str) syncProcess :: String -> CreateProcess -> IO ExitCode #if mingw32_HOST_OS syncProcess _fun c = do (_,_,_,p) <- createProcess c waitForProcess p #else syncProcess fun c = do -- The POSIX version of system needs to do some manipulation of signal -- handlers. Since we're going to be synchronously waiting for the child, -- we want to ignore ^C in the parent, but handle it the default way -- in the child (using SIG_DFL isn't really correct, it should be the -- original signal handler, but the GHC RTS will have already set up -- its own handler and we don't want to use that). old_int <- installHandler sigINT Ignore Nothing old_quit <- installHandler sigQUIT Ignore Nothing (_,_,_,p) <- runGenProcess_ fun c (Just defaultSignal) (Just defaultSignal) r <- waitForProcess p _ <- installHandler sigINT old_int Nothing _ <- installHandler sigQUIT old_quit Nothing return r #endif /* mingw32_HOST_OS */ #endif /* __GLASGOW_HASKELL__ */ {-| The computation @'rawSystem' cmd args@ runs the operating system command @cmd@ in such a way that it receives as arguments the @args@ strings exactly as given, with no funny escaping or shell meta-syntax expansion. It will therefore behave more portably between operating systems than 'system'. The return codes and possible failures are the same as for 'system'. -} rawSystem :: String -> [String] -> IO ExitCode #ifdef __GLASGOW_HASKELL__ rawSystem cmd args = syncProcess "rawSystem" (proc cmd args) #elif !mingw32_HOST_OS -- crude fallback implementation: could do much better than this under Unix rawSystem cmd args = system (showCommandForUser cmd args) #else /* mingw32_HOST_OS && ! __GLASGOW_HASKELL__ */ # if __HUGS__ rawSystem cmd args = system (cmd ++ showCommandForUser "" args) # else rawSystem cmd args = system (showCommandForUser cmd args) #endif #endif -- | Given a program @p@ and arguments @args@, -- @showCommandForUser p args@ returns a string suitable for pasting -- into sh (on POSIX OSs) or cmd.exe (on Windows). showCommandForUser :: FilePath -> [String] -> String showCommandForUser cmd args = unwords (map translate (cmd : args)) #ifndef __HUGS__ -- ---------------------------------------------------------------------------- -- terminateProcess -- | Attempts to terminate the specified process. This function should -- not be used under normal circumstances - no guarantees are given regarding -- how cleanly the process is terminated. To check whether the process -- has indeed terminated, use 'getProcessExitCode'. -- -- On Unix systems, 'terminateProcess' sends the process the SIGTERM signal. -- On Windows systems, the Win32 @TerminateProcess@ function is called, passing -- an exit code of 1. -- -- Note: on Windows, if the process was a shell command created by -- 'createProcess' with 'shell', or created by 'runCommand' or -- 'runInteractiveCommand', then 'terminateProcess' will only -- terminate the shell, not the command itself. On Unix systems, both -- processes are in a process group and will be terminated together. terminateProcess :: ProcessHandle -> IO () terminateProcess ph = do withProcessHandle_ ph $ \p_ -> case p_ of ClosedHandle _ -> return p_ OpenHandle h -> do throwErrnoIfMinus1Retry_ "terminateProcess" $ c_terminateProcess h return p_ -- does not close the handle, we might want to try terminating it -- again, or get its exit code. -- ---------------------------------------------------------------------------- -- interruptProcessGroupOf -- | Sends an interrupt signal to the process group of the given process. -- -- On Unix systems, it sends the group the SIGINT signal. -- -- On Windows systems, it generates a CTRL_BREAK_EVENT and will only work for -- processes created using 'createProcess' and setting the 'create_group' flag interruptProcessGroupOf :: ProcessHandle -- ^ Lead process in the process group -> IO () interruptProcessGroupOf ph = do #if mingw32_HOST_OS withProcessHandle_ ph $ \p_ -> do case p_ of ClosedHandle _ -> return p_ OpenHandle h -> do pid <- getProcessId h generateConsoleCtrlEvent cTRL_BREAK_EVENT pid return p_ #else withProcessHandle_ ph $ \p_ -> do case p_ of ClosedHandle _ -> return p_ OpenHandle h -> do signalProcessGroup sigINT h return p_ #endif -- ---------------------------------------------------------------------------- -- getProcessExitCode {- | This is a non-blocking version of 'waitForProcess'. If the process is still running, 'Nothing' is returned. If the process has exited, then @'Just' e@ is returned where @e@ is the exit code of the process. -} getProcessExitCode :: ProcessHandle -> IO (Maybe ExitCode) getProcessExitCode ph = do withProcessHandle ph $ \p_ -> case p_ of ClosedHandle e -> return (p_, Just e) OpenHandle h -> alloca $ \pExitCode -> do res <- throwErrnoIfMinus1Retry "getProcessExitCode" $ c_getProcessExitCode h pExitCode code <- peek pExitCode if res == 0 then return (p_, Nothing) else do closePHANDLE h let e | code == 0 = ExitSuccess | otherwise = ExitFailure (fromIntegral code) return (ClosedHandle e, Just e) -- ---------------------------------------------------------------------------- -- Interface to C bits foreign import ccall unsafe "terminateProcess" c_terminateProcess :: PHANDLE -> IO CInt foreign import ccall unsafe "getProcessExitCode" c_getProcessExitCode :: PHANDLE -> Ptr CInt -> IO CInt #if __GLASGOW_HASKELL__ < 701 -- not available prior to 7.1 #define interruptible safe #endif foreign import ccall interruptible "waitForProcess" -- NB. safe - can block c_waitForProcess :: PHANDLE -> Ptr CInt -> IO CInt #endif /* !__HUGS__ */