82 lines
2.0 KiB
Haskell
82 lines
2.0 KiB
Haskell
{- portable environment variables
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-
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- Copyright 2013 Joey Hess <joey@kitenet.net>
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-
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- License: BSD-2-clause
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-}
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{-# LANGUAGE CPP #-}
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module Utility.Env where
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#ifdef mingw32_HOST_OS
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import Utility.Exception
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import Control.Applicative
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import Data.Maybe
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import qualified System.Environment as E
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#else
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import qualified System.Posix.Env as PE
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#endif
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getEnv :: String -> IO (Maybe String)
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#ifndef mingw32_HOST_OS
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getEnv = PE.getEnv
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#else
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getEnv = catchMaybeIO . E.getEnv
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#endif
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getEnvDefault :: String -> String -> IO String
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#ifndef mingw32_HOST_OS
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getEnvDefault = PE.getEnvDefault
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#else
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getEnvDefault var fallback = fromMaybe fallback <$> getEnv var
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#endif
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getEnvironment :: IO [(String, String)]
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#ifndef mingw32_HOST_OS
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getEnvironment = PE.getEnvironment
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#else
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getEnvironment = E.getEnvironment
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#endif
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{- Returns True if it could successfully set the environment variable.
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-
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- There is, apparently, no way to do this in Windows. Instead,
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- environment varuables must be provided when running a new process. -}
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setEnv :: String -> String -> Bool -> IO Bool
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#ifndef mingw32_HOST_OS
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setEnv var val overwrite = do
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PE.setEnv var val overwrite
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return True
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#else
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setEnv _ _ _ = return False
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#endif
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{- Returns True if it could successfully unset the environment variable. -}
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unsetEnv :: String -> IO Bool
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#ifndef mingw32_HOST_OS
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unsetEnv var = do
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PE.unsetEnv var
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return True
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#else
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unsetEnv _ = return False
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#endif
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{- Adds the environment variable to the input environment. If already
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- present in the list, removes the old value.
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-
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- This does not really belong here, but Data.AssocList is for some reason
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- buried inside hxt.
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-}
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addEntry :: Eq k => k -> v -> [(k, v)] -> [(k, v)]
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addEntry k v l = ( (k,v) : ) $! delEntry k l
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addEntries :: Eq k => [(k, v)] -> [(k, v)] -> [(k, v)]
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addEntries = foldr (.) id . map (uncurry addEntry) . reverse
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delEntry :: Eq k => k -> [(k, v)] -> [(k, v)]
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delEntry _ [] = []
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delEntry k (x@(k1,_) : rest)
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| k == k1 = rest
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| otherwise = ( x : ) $! delEntry k rest
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