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|
{-# LANGUAGE Trustworthy #-}
#if __GLASGOW_HASKELL__ >= 709
{-# OPTIONS_GHC -fno-warn-trustworthy-safe #-}
#endif
-----------------------------------------------------------------------------
-- |
-- Module : System.Posix.Env.ByteString
-- Copyright : (c) The University of Glasgow 2002
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : non-portable (requires POSIX)
--
-- POSIX environment support
--
-----------------------------------------------------------------------------
module System.Posix.Env.ByteString (
-- * Environment Variables
getEnv
, getEnvDefault
, getEnvironmentPrim
, getEnvironment
, putEnv
, setEnv
, unsetEnv
-- * Program arguments
, getArgs
) where
#include "HsUnix.h"
import Foreign
import Foreign.C
import Control.Monad ( liftM )
import Data.Maybe ( fromMaybe )
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8 as BC
import Data.ByteString (ByteString)
-- |'getEnv' looks up a variable in the environment.
getEnv :: ByteString -> IO (Maybe ByteString)
getEnv name = do
litstring <- B.useAsCString name c_getenv
if litstring /= nullPtr
then liftM Just $ B.packCString litstring
else return Nothing
-- |'getEnvDefault' is a wrapper around 'getEnv' where the
-- programmer can specify a fallback if the variable is not found
-- in the environment.
getEnvDefault :: ByteString -> ByteString -> IO ByteString
getEnvDefault name fallback = liftM (fromMaybe fallback) (getEnv name)
foreign import ccall unsafe "getenv"
c_getenv :: CString -> IO CString
getEnvironmentPrim :: IO [ByteString]
getEnvironmentPrim = do
c_environ <- getCEnviron
arr <- peekArray0 nullPtr c_environ
mapM B.packCString arr
getCEnviron :: IO (Ptr CString)
#if darwin_HOST_OS
-- You should not access _environ directly on Darwin in a bundle/shared library.
-- See #2458 and http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man7/environ.7.html
getCEnviron = nsGetEnviron >>= peek
foreign import ccall unsafe "_NSGetEnviron"
nsGetEnviron :: IO (Ptr (Ptr CString))
#else
getCEnviron = peek c_environ_p
foreign import ccall unsafe "&environ"
c_environ_p :: Ptr (Ptr CString)
#endif
-- |'getEnvironment' retrieves the entire environment as a
-- list of @(key,value)@ pairs.
getEnvironment :: IO [(ByteString,ByteString)]
getEnvironment = do
env <- getEnvironmentPrim
return $ map (dropEq.(BC.break ((==) '='))) env
where
dropEq (x,y)
| BC.head y == '=' = (x,B.tail y)
| otherwise = error $ "getEnvironment: insane variable " ++ BC.unpack x
-- |The 'unsetEnv' function deletes all instances of the variable name
-- from the environment.
unsetEnv :: ByteString -> IO ()
#ifdef HAVE_UNSETENV
unsetEnv name = B.useAsCString name $ \ s ->
throwErrnoIfMinus1_ "unsetenv" (c_unsetenv s)
foreign import ccall unsafe "__hsunix_unsetenv"
c_unsetenv :: CString -> IO CInt
#else
unsetEnv name = putEnv (name ++ "=")
#endif
-- |'putEnv' function takes an argument of the form @name=value@
-- and is equivalent to @setEnv(key,value,True{-overwrite-})@.
putEnv :: ByteString -> IO ()
putEnv keyvalue = B.useAsCString keyvalue $ \s ->
throwErrnoIfMinus1_ "putenv" (c_putenv s)
foreign import ccall unsafe "putenv"
c_putenv :: CString -> IO CInt
{- |The 'setEnv' function inserts or resets the environment variable name in
the current environment list. If the variable @name@ does not exist in the
list, it is inserted with the given value. If the variable does exist,
the argument @overwrite@ is tested; if @overwrite@ is @False@, the variable is
not reset, otherwise it is reset to the given value.
-}
setEnv :: ByteString -> ByteString -> Bool {-overwrite-} -> IO ()
#ifdef HAVE_SETENV
setEnv key value ovrwrt = do
B.useAsCString key $ \ keyP ->
B.useAsCString value $ \ valueP ->
throwErrnoIfMinus1_ "setenv" $
c_setenv keyP valueP (fromIntegral (fromEnum ovrwrt))
foreign import ccall unsafe "setenv"
c_setenv :: CString -> CString -> CInt -> IO CInt
#else
setEnv key value True = putEnv (key++"="++value)
setEnv key value False = do
res <- getEnv key
case res of
Just _ -> return ()
Nothing -> putEnv (key++"="++value)
#endif
-- | Computation 'getArgs' returns a list of the program's command
-- line arguments (not including the program name), as 'ByteString's.
--
-- Unlike 'System.Environment.getArgs', this function does no Unicode
-- decoding of the arguments; you get the exact bytes that were passed
-- to the program by the OS. To interpret the arguments as text, some
-- Unicode decoding should be applied.
--
getArgs :: IO [ByteString]
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 B.packCString
foreign import ccall unsafe "getProgArgv"
getProgArgv :: Ptr CInt -> Ptr (Ptr CString) -> IO ()
|
