-- |
-- Module : System.Cmd
-- Copyright : (c) The University of Glasgow 2001
--- License : BSD-style (see the file libraries/core/LICENSE)
+-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : portable
--
--- Executing a command.
+-- Executing an external command.
--
-----------------------------------------------------------------------------
module System.Cmd
- ( system -- :: String -> IO ExitCode
+ ( system, -- :: String -> IO ExitCode
+ rawSystem, -- :: FilePath -> [String] -> IO ExitCode
) where
import Prelude
-import System.Exit
-import Foreign.C
+import System.Exit ( ExitCode )
#ifdef __GLASGOW_HASKELL__
-import GHC.IOBase
+import System.Process
+import GHC.IOBase ( ioException, IOException(..), IOErrorType(..) )
+#if !defined(mingw32_HOST_OS)
+import System.Process.Internals
+import System.Posix.Signals
+#endif
+#endif
+
+#ifdef __HUGS__
+import Hugs.System
+#endif
+
+#ifdef __NHC__
+import System (system)
#endif
-- ---------------------------------------------------------------------------
-- system
--- Computation `system cmd' returns the exit code
--- produced when the operating system processes the command `cmd'.
+{-|
+Computation @system cmd@ returns the exit code
+produced when the operating system processes the 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.
+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' is implemented using Windows's native system
+call, which ignores the @SHELL@ environment variable, and always
+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 (IOError Nothing InvalidArgument "system" "null command" Nothing)
-system cmd =
- withCString cmd $ \s -> do
- status <- throwErrnoIfMinus1 "system" (primSystem s)
- case status of
- 0 -> return ExitSuccess
- n -> return (ExitFailure n)
-
-foreign import ccall unsafe "systemCmd" primSystem :: CString -> IO Int
+system str = do
+#if mingw32_HOST_OS
+ p <- runCommand str
+ waitForProcess p
+#else
+ -- 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
+ (cmd,args) <- commandToProcess str
+ p <- runProcessPosix "runCommand" cmd args Nothing Nothing
+ Nothing Nothing Nothing
+ (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 = do
+
+#if mingw32_HOST_OS
+ p <- runProcess cmd args Nothing Nothing Nothing Nothing Nothing
+ waitForProcess p
+#else
+ old_int <- installHandler sigINT Ignore Nothing
+ old_quit <- installHandler sigQUIT Ignore Nothing
+ p <- runProcessPosix "rawSystem" cmd args Nothing Nothing
+ Nothing Nothing Nothing
+ (Just defaultSignal) (Just defaultSignal)
+ r <- waitForProcess p
+ installHandler sigINT old_int Nothing
+ installHandler sigQUIT old_quit Nothing
+ return r
+#endif
+
+#elif !mingw32_HOST_OS
+-- crude fallback implementation: could do much better than this under Unix
+rawSystem cmd args = system (unwords (map translate (cmd:args)))
+
+translate :: String -> String
+translate str = '\'' : foldr escape "'" str
+ where escape '\'' = showString "'\\''"
+ escape c = showChar c
+#else /* mingw32_HOST_OS && ! __GLASGOW_HASKELL__ */
+# if __HUGS__
+rawSystem cmd args = system (unwords (cmd : map translate args))
+# else
+rawSystem cmd args = system (unwords (map translate (cmd:args)))
+#endif
+
+-- copied from System.Process (qv)
+translate :: String -> String
+translate str = '"' : snd (foldr escape (True,"\"") str)
+ where escape '"' (b, str) = (True, '\\' : '"' : str)
+ escape '\\' (True, str) = (True, '\\' : '\\' : str)
+ escape '\\' (False, str) = (False, '\\' : str)
+ escape c (b, str) = (False, c : str)
+#endif
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