finally really add back custom-setup stanza

Fourth or fifth try at this and finally found a way to make it work.

Absurd amount of busy-work forced on me by change in cabal's behavior.
Split up Utility modules that need posix stuff out of ones used by
Setup. Various other hacks around inability for Setup to use anything
that ifdefs a use of unix.

Probably lost a full day of my life to this.
This is how build systems make their users hate them. Just saying.

2 files changed, 62 insertions, 0 deletions

diff --git a/Utility/Env/Basic.hs b/Utility/Env/Basic.hs
new file mode 100644
index 000000000..38295bea0
--- /dev/null
+++ b/Utility/Env/Basic.hs
@@ -0,0 +1,22 @@
+{- portable environment variables, without any dependencies
+ -
+ - Copyright 2013 Joey Hess <id@joeyh.name>
+ -
+ - License: BSD-2-clause
+ -}
+
+{-# OPTIONS_GHC -fno-warn-tabs #-}
+
+module Utility.Env.Basic where
+
+import Utility.Exception
+import Control.Applicative
+import Data.Maybe
+import Prelude
+import qualified System.Environment as E
+
+getEnv :: String -> IO (Maybe String)
+getEnv = catchMaybeIO . E.getEnv
+
+getEnvDefault :: String -> String -> IO String
+getEnvDefault var fallback = fromMaybe fallback <$> getEnv var
diff --git a/Utility/Env/Set.hs b/Utility/Env/Set.hs
new file mode 100644
index 000000000..fd8d5140d
--- /dev/null
+++ b/Utility/Env/Set.hs
@@ -0,0 +1,40 @@
+{- 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
+#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