git-annex/Utility/Env.hs

39 lines
910 B
Haskell
Executable file

{- portable environment variables
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Utility.Env where
#ifdef __WINDOWS__
import qualified System.Environment as E
import Utility.Exception
#else
import qualified System.Posix.Environment as E
#endif
{- Posix getEnv is faster than the one in System.Environment,
- so use when available. -}
getEnv :: String -> IO (Maybe String)
#ifndef __WINDOWS__
getEnv = E.getEnv
#else
getEnv = catchMaybeIO . E.getEnv
#endif
{- Returns True if it could successfully set the environment variable.
-
- There is, apparently, no way to do this in Windows. Instead,
- environment varuables must be provided when running a new process. -}
setEnv :: String -> String -> IO Bool
#ifndef __WINDOWS__
setEnv var val = do
E.setEnv var val
return True
#else
setEnv _ _ = return False
#endif