+% -----------------------------------------------------------------------------
+% $Id: System.lhs,v 1.29 2001/01/11 17:51:02 simonmar Exp $
%
-% (c) The AQUA Project, Glasgow University, 1994-1996
+% (c) The University of Glasgow, 1994-2000
%
\section[System]{Module @System@}
\begin{code}
-module System (
- ExitCode(ExitSuccess,ExitFailure),
- getArgs, getProgName, getEnv, system, exitWith
+{-# OPTIONS -#include "cbits/stgio.h" #-}
+module System
+ (
+ ExitCode(ExitSuccess,ExitFailure)
+ , getArgs -- :: IO [String]
+ , getProgName -- :: IO String
+ , getEnv -- :: String -> IO String
+ , system -- :: String -> IO ExitCode
+ , exitWith -- :: ExitCode -> IO a
+ , exitFailure -- :: IO a
) where
+\end{code}
+\begin{code}
+import Monad
import Prelude
-import PrelAddr
-import PrelIOBase ( IOError(..), IOErrorType(..), constructErrorAndFailWithInfo )
-import PrelPack ( unpackCString )
-
+import PrelCString
+import PrelCTypes
+import PrelMarshalArray
+import PrelPtr
+import PrelStorable
+import PrelIOBase ( IOException(..), ioException,
+ IOErrorType(..), constructErrorAndFailWithInfo )
\end{code}
%*********************************************************
\end{code}
-
-%*********************************************************
-%* *
-\subsection{Other functions}
-%* *
-%*********************************************************
-
-\begin{code}
-getArgs :: IO [String]
-getProgName :: IO String
-getEnv :: String -> IO String
-system :: String -> IO ExitCode
-exitWith :: ExitCode -> IO a
-\end{code}
-
Computation $getArgs$ returns a list of the program's command
line arguments (not including the program name).
\begin{code}
-getArgs = return (unpackArgv ``prog_argv'' (``prog_argc''::Int))
+getArgs :: IO [String]
+getArgs = unpackArgv primArgv primArgc
+
+foreign import ccall "get_prog_argv" unsafe primArgv :: Ptr (Ptr CChar)
+foreign import ccall "get_prog_argc" unsafe primArgc :: Int
\end{code}
Computation $getProgName$ returns the name of the program
as it was invoked.
\begin{code}
-getProgName = return (unpackProgName ``prog_argv'')
+getProgName :: IO String
+getProgName = unpackProgName primArgv
\end{code}
Computation $getEnv var$ returns the value
\end{itemize}
\begin{code}
-getEnv name = do
- litstring <- _ccall_ getenv name
- if litstring /= ``NULL''
- then return (unpackCString litstring)
- else fail (IOError Nothing NoSuchThing "getEnv"
- ("environment variable: " ++ name))
+getEnv :: String -> IO String
+getEnv name =
+ withUnsafeCString name $ \s -> do
+ litstring <- _getenv s
+ if litstring /= nullPtr
+ then peekCString litstring
+ else ioException (IOError Nothing NoSuchThing "getEnv"
+ "no environment variable" (Just name))
+
+foreign import ccall "getenv" unsafe _getenv :: UnsafeCString -> IO (Ptr CChar)
\end{code}
Computation $system cmd$ returns the exit code
\end{itemize}
\begin{code}
-system "" = fail (IOError Nothing InvalidArgument "system" "null command")
-system cmd = do
- status <- _ccall_ systemCmd cmd
+system :: String -> IO ExitCode
+system "" = ioException (IOError Nothing InvalidArgument "system" "null command" Nothing)
+system cmd =
+ withUnsafeCString cmd $ \s -> do
+ status <- primSystem s
case status of
0 -> return ExitSuccess
-1 -> constructErrorAndFailWithInfo "system" cmd
n -> return (ExitFailure n)
+foreign import ccall "systemCmd" unsafe primSystem :: UnsafeCString -> IO Int
\end{code}
-Computation $exitWith code$ terminates the
-program, returning {\em code} to the program's caller.
+@exitWith code@ terminates the program, returning {\em code} to the program's caller.
Before it terminates, any open or semi-closed handles are first closed.
\begin{code}
+exitWith :: ExitCode -> IO a
exitWith ExitSuccess = do
- _ccall_ EXIT (0::Int)
- fail (IOError Nothing OtherError "exitWith" "exit should not return")
+ primExit 0
+ ioException (IOError Nothing OtherError "exitWith" "exit should not return" Nothing)
exitWith (ExitFailure n)
- | n == 0 = fail (IOError Nothing InvalidArgument "exitWith" "ExitFailure 0")
+ | n == 0 = ioException (IOError Nothing InvalidArgument "exitWith" "ExitFailure 0" Nothing)
| otherwise = do
- _ccall_ EXIT n
- fail (IOError Nothing OtherError "exitWith" "exit should not return")
+ primExit n
+ ioException (IOError Nothing OtherError "exitWith" "exit should not return" Nothing)
+
+-- NOTE: shutdownHaskellAndExit must be called "safe", because it *can*
+-- re-enter Haskell land through finalizers.
+foreign import ccall "shutdownHaskellAndExit" primExit :: Int -> IO ()
+
+exitFailure :: IO a
+exitFailure = exitWith (ExitFailure 1)
\end{code}
%*********************************************************
\begin{code}
-type CHAR_STAR_STAR = Addr -- this is all a HACK
-type CHAR_STAR = Addr
-
-unpackArgv :: CHAR_STAR_STAR -> Int -> [String] -- argv[1 .. argc-1]
-unpackProgName :: CHAR_STAR_STAR -> String -- argv[0]
-
-unpackArgv argv argc = unpack 1
- where
- unpack :: Int -> [String]
- unpack n
- = if (n >= argc)
- then ([] :: [String])
- else case (indexAddrOffAddr argv n) of { item ->
- unpackCString item : unpack (n + 1) }
-
-unpackProgName argv
- = case (indexAddrOffAddr argv 0) of { prog ->
- de_slash [] (unpackCString prog) }
+unpackArgv :: Ptr (Ptr CChar) -> Int -> IO [String] -- argv[1 .. argc-1]
+unpackArgv argv argc
+ = peekArray (argc-1) (advancePtr argv 1) >>= mapM peekCString
+
+unpackProgName :: Ptr (Ptr CChar) -> IO String -- argv[0]
+unpackProgName argv = do
+ s <- peekElemOff argv 0 >>= peekCString
+ return (de_slash "" s)
where
-- re-start accumulating at every '/'
de_slash :: String -> String -> String
- de_slash acc [] = reverse acc
- de_slash acc ('/':xs) = de_slash [] xs
- de_slash acc (x:xs) = de_slash (x:acc) xs
+ de_slash acc [] = reverse acc
+ de_slash _acc ('/':xs) = de_slash [] xs
+ de_slash acc (x:xs) = de_slash (x:acc) xs
\end{code}