refactor

Utility/CoProcess.hs

@@ -0,0 +1,35 @@
+{- Interface for running a shell command as a coprocess,
+ - sending it queries and getting back results.
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Utility.CoProcess (
+	CoProcessHandle,
+	start,
+	stop,
+	query
+) where
+
+import System.Cmd.Utils
+
+import Common
+
+type CoProcessHandle = (PipeHandle, Handle, Handle)
+
+start :: FilePath -> [String] -> IO CoProcessHandle
+start command params = hPipeBoth command params
+
+stop :: CoProcessHandle -> IO ()
+stop (pid, from, to) = do
+	hClose to
+	hClose from
+	forceSuccess pid
+
+query :: CoProcessHandle -> (Handle -> IO a) -> (Handle -> IO b) -> IO b
+query (_, from, to) send receive = do
+	_ <- send to
+	hFlush to
+	receive from