git-annex/Utility/Env/Set.hs
2018-01-04 14:23:11 -04:00

41 lines
905 B
Haskell

{- portable environment variables
-
- Copyright 2013 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
module Utility.Env.Set where
#ifdef mingw32_HOST_OS
import qualified System.Environment as E
import qualified System.SetEnv
import Utility.Env
#else
import qualified System.Posix.Env as PE
#endif
{- Sets an environment variable. To overwrite an existing variable,
- overwrite must be True.
-
- On Windows, setting a variable to "" unsets it. -}
setEnv :: String -> String -> Bool -> IO ()
#ifndef mingw32_HOST_OS
setEnv var val overwrite = PE.setEnv var val overwrite
#else
setEnv var val True = System.SetEnv.setEnv var val
setEnv var val False = do
r <- getEnv var
case r of
Nothing -> setEnv var val True
Just _ -> return ()
#endif
unsetEnv :: String -> IO ()
#ifndef mingw32_HOST_OS
unsetEnv = PE.unsetEnv
#else
unsetEnv = System.SetEnv.unsetEnv
#endif