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|
-----------------------------------------------------------------------------
--
-- Module : System.Environment
-- Copyright : (c) The University of Glasgow 2001
-- License : BSD-style (see the file libraries/core/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : portable
--
-- $Id: Environment.hs,v 1.4 2002/01/02 14:40:11 simonmar Exp $
--
-- Miscellaneous information about the system environment.
--
-----------------------------------------------------------------------------
module System.Environment
(
, getArgs -- :: IO [String]
, getProgName -- :: IO String
, getEnv -- :: String -> IO String
) where
import Prelude
import Foreign
import Foreign.C
import Control.Monad
#ifdef __GLASGOW_HASKELL__
import GHC.IOBase
#endif
-- ---------------------------------------------------------------------------
-- getArgs, getProgName, getEnv
-- Computation `getArgs' returns a list of the program's command
-- line arguments (not including the program name).
getArgs :: IO [String]
getArgs =
alloca $ \ p_argc ->
alloca $ \ p_argv -> do
getProgArgv p_argc p_argv
p <- fromIntegral `liftM` peek p_argc
argv <- peek p_argv
peekArray (p - 1) (advancePtr argv 1) >>= mapM peekCString
foreign import "getProgArgv" unsafe
getProgArgv :: Ptr CInt -> Ptr (Ptr CString) -> IO ()
-- Computation `getProgName' returns the name of the program
-- as it was invoked.
getProgName :: IO String
getProgName =
alloca $ \ p_argc ->
alloca $ \ p_argv -> do
getProgArgv p_argc p_argv
argv <- peek p_argv
unpackProgName argv
unpackProgName :: Ptr (Ptr CChar) -> IO String -- argv[0]
unpackProgName argv = do
s <- peekElemOff argv 0 >>= peekCString
return (basename s)
where
basename :: String -> String
basename f = go f f
where
go acc [] = acc
go acc (x:xs)
| isPathSeparator x = go xs xs
| otherwise = go acc xs
isPathSeparator :: Char -> Bool
isPathSeparator '/' = True
#ifdef mingw32_TARGET_OS
isPathSeparator '\\' = True
#endif
isPathSeparator _ = False
-- Computation `getEnv var' returns the value
-- of the environment variable {\em var}.
-- This computation may fail with
-- NoSuchThing: The environment variable does not exist.
getEnv :: String -> IO String
getEnv name =
withCString name $ \s -> do
litstring <- c_getenv s
if litstring /= nullPtr
then peekCString litstring
else ioException (IOError Nothing NoSuchThing "getEnv"
"no environment variable" (Just name))
foreign import ccall "getenv" unsafe
c_getenv :: CString -> IO (Ptr CChar)
|
