Use ByteString-based getEnvironment on *nix systems

wai-extra/Network/Wai/Handler/CGI.hs

@@ -13,7 +13,6 @@ module Network.Wai.Handler.CGI
 import Network.Wai
 import Network.Wai.Internal
 import Network.Socket (getAddrInfo, addrAddress)
-import System.Environment (getEnvironment)
 import Data.Maybe (fromMaybe)
 import Control.Exception (mask)
 import qualified Data.ByteString.Char8 as B
@@ -35,6 +34,15 @@ import qualified Data.CaseInsensitive as CI
 import Data.Monoid (mappend)
 import Data.Conduit
 
+#if WINDOWS
+import System.Environment (getEnvironment)
+#else
+import qualified System.Posix.Env.ByteString as Env
+
+getEnvironment :: IO [(String, String)]
+getEnvironment = map (B.unpack *** B.unpack) `fmap` Env.getEnvironment
+#endif
+
 safeRead :: Read a => a -> String -> a
 safeRead d s =
   case reads s of

wai-extra/wai-extra.cabal

@@ -47,6 +47,11 @@ Library
                    , word8
                    , lifted-base               >= 0.1.2
 
+  if os(windows)
+      cpp-options:   -DWINDOWS
+  else
+      build-depends: unix
+
   Exposed-modules:   Network.Wai.Handler.CGI
                      Network.Wai.Middleware.AcceptOverride
                      Network.Wai.Middleware.Autohead