-- |
-- Module : System.Environment
-- 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
--
--- $Id: Environment.hs,v 1.6 2002/04/24 16:31:45 simonmar Exp $
---
-- Miscellaneous information about the system environment.
--
-----------------------------------------------------------------------------
module System.Environment
(
- , getArgs -- :: IO [String]
- , getProgName -- :: IO String
- , getEnv -- :: String -> IO String
+ getArgs, -- :: IO [String]
+ getProgName, -- :: IO String
+ getEnv, -- :: String -> IO String
+#ifdef __GLASGOW_HASKELL__
+ withArgs,
+ withProgName,
+#endif
) where
import Prelude
+import Control.Exception ( bracket )
+#ifdef __GLASGOW_HASKELL__
import Foreign
import Foreign.C
import Control.Monad
-
-#ifdef __GLASGOW_HASKELL__
import GHC.IOBase
#endif
+#ifdef __HUGS__
+import Hugs.System
+#endif
+
+#ifdef __NHC__
+import System
+ ( getArgs
+ , getProgName
+ , getEnv
+ )
+#endif
+
-- ---------------------------------------------------------------------------
-- getArgs, getProgName, getEnv
-- Computation `getArgs' returns a list of the program's command
-- line arguments (not including the program name).
+#ifdef __GLASGOW_HASKELL__
getArgs :: IO [String]
getArgs =
alloca $ \ p_argc ->
foreign import ccall unsafe "getProgArgv"
getProgArgv :: Ptr CInt -> Ptr (Ptr CString) -> IO ()
--- Computation `getProgName' returns the name of the program
--- as it was invoked.
+{-|
+Computation 'getProgName' returns the name of the program as it was
+invoked.
+However, this is hard-to-impossible to implement on some non-Unix
+OSes, so instead, for maximum portability, we just return the leafname
+of the program as invoked. Even then there are some differences
+between platforms: on Windows, for example, a program invoked as foo
+is probably really @FOO.EXE@, and that is what 'getProgName' will return.
+-}
getProgName :: IO String
getProgName =
alloca $ \ p_argc ->
foreign import ccall unsafe "getenv"
c_getenv :: CString -> IO (Ptr CChar)
+
+{-|
+@withArgs args act@ - while executing action @act@, have 'System.getArgs'
+return @args@.
+-}
+withArgs xs act = do
+ p <- System.Environment.getProgName
+ withArgv (p:xs) act
+
+{-|
+@withProgName name act@ - while executing action @act@, have 'System.getProgName'return @name@.
+-}
+withProgName nm act = do
+ xs <- System.Environment.getArgs
+ withArgv (nm:xs) act
+
+-- Worker routine which marshals and replaces an argv vector for
+-- the duration of an action.
+
+withArgv new_args act = do
+ pName <- System.Environment.getProgName
+ existing_args <- System.Environment.getArgs
+ bracket (setArgs new_args)
+ (\argv -> do setArgs (pName:existing_args); freeArgv argv)
+ (const act)
+
+freeArgv :: Ptr CString -> IO ()
+freeArgv argv = do
+ size <- lengthArray0 nullPtr argv
+ sequence_ [peek (argv `advancePtr` i) >>= free | i <- [size, size-1 .. 0]]
+ free argv
+
+setArgs :: [String] -> IO (Ptr CString)
+setArgs argv = do
+ vs <- mapM newCString argv >>= newArray0 nullPtr
+ setArgsPrim (length argv) vs
+ return vs
+
+foreign import ccall unsafe "setProgArgv"
+ setArgsPrim :: Int -> Ptr CString -> IO ()
+#endif /* __GLASGOW_HASKELL__ */