port transferkeys to windows; make stopping in progress transfers work too (probably)

transferkeys had used special FDs for communication, but that would be
quite annoying to do in Windows.

Instead, use stdin and stdout. But, to avoid commands like rsync stomping
on them and messing up the communications channel, they're duplicated to a
different handle; stdin is replaced with a null handle, and stdout is
replaced with a copy of stderr. This should all work in windows too.

Stopping in progress transfers may work on windows.. if the types unify
anyway. ;) May need some more porting.

Assistant/TransferSlots.hs

@@ -38,6 +38,8 @@ import qualified Control.Concurrent.MSemN as MSemN
 #ifndef mingw32_HOST_OS
 import System.Posix.Process (getProcessGroupIDOf)
 import System.Posix.Signals (signalProcessGroup, sigTERM, sigKILL)
+#else
+import System.Win32.Console (generateConsoleCtrlEvent, cTRL_C_EVENT, cTRL_BREAK_EVENT)
 #endif
 
 type TransferGenerator = Assistant (Maybe (Transfer, TransferInfo, Transferrer -> Assistant ()))
@@ -252,18 +254,21 @@ cancelTransfer pause t = do
 	signalthread tid
 		| pause = throwTo tid PauseTransfer
 		| otherwise = killThread tid
+	{- In order to stop helper processes like rsync,
+	 - kill the whole process group of the process
+	 - running the transfer. -}
 	killproc pid = void $ tryIO $ do
 #ifndef mingw32_HOST_OS
-		{- In order to stop helper processes like rsync,
-		 - kill the whole process group of the process
-		 - running the transfer. -}
 		g <- getProcessGroupIDOf pid
 		void $ tryIO $ signalProcessGroup sigTERM g
-		threadDelay 50000 -- 0.05 second grace period
+		graceperiod
 		void $ tryIO $ signalProcessGroup sigKILL g
 #else
-		error "TODO: cancelTransfer not implemented on Windows"
+		void $ tryIO $ generateConsoleCtrlEvent cTRL_C_EVENT pid
+		graceperiod
+		void $ tryIO $ generateConsoleCtrlEvent cTRL_BREAK_EVENT pid
 #endif
+	graceperiod = threadDelay 50000 -- 0.05 second
 
 {- Start or resume a transfer. -}
 startTransfer :: Transfer -> Assistant ()

Assistant/TransferrerPool.hs

@@ -5,8 +5,6 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-{-# LANGUAGE CPP #-}
-
 module Assistant.TransferrerPool where
 
 import Assistant.Common
@@ -14,12 +12,10 @@ import Assistant.Types.TransferrerPool
 import Logs.Transfer
 import Utility.Batch
 
-#ifndef mingw32_HOST_OS
 import qualified Command.TransferKeys as T
-#endif
 
 import Control.Concurrent.STM
-import System.Process (create_group)
+import System.Process (create_group, std_in, std_out)
 import Control.Exception (throw)
 import Control.Concurrent
 
@@ -44,46 +40,30 @@ withTransferrer program batchmaker pool a = do
  - finish. -}
 performTransfer :: Transferrer -> Transfer -> AssociatedFile -> IO Bool
 performTransfer transferrer t f = catchBoolIO $ do
-#ifndef mingw32_HOST_OS
 	T.sendRequest t f (transferrerWrite transferrer)
 	T.readResponse (transferrerRead transferrer)
-#else
-	error "TODO performTransfer not implemented on Windows"
-#endif
 
-{- Starts a new git-annex transferkeys process, setting up a pipe
+{- Starts a new git-annex transferkeys process, setting up handles
  - that will be used to communicate with it. -}
 mkTransferrer :: FilePath -> BatchCommandMaker -> IO Transferrer
 mkTransferrer program batchmaker = do
-#ifndef mingw32_HOST_OS
-	(myread, twrite) <- createPipe
-	(tread, mywrite) <- createPipe
-	mapM_ (\fd -> setFdOption fd CloseOnExec True) [myread, mywrite]
-	let params =
-		[ Param "transferkeys"
-		, Param "--readfd", Param $ show tread
-		, Param "--writefd", Param $ show twrite
-		]
 	{- It runs as a batch job. -}
-	let (program', params') = batchmaker (program, params)
+	let (program', params') = batchmaker (program, [Param "transferkeys"])
 	{- It's put into its own group so that the whole group can be
 	 - killed to stop a transfer. -}
-	(_, _, _, pid) <- createProcess (proc program' $ toCommand params')
-		{ create_group = True }
-	closeFd twrite
-	closeFd tread
-	myreadh <- fdToHandle myread
-	mywriteh <- fdToHandle mywrite
-	fileEncoding myreadh
-	fileEncoding mywriteh
+	(Just writeh, Just readh, _, pid) <- createProcess
+		(proc program' $ toCommand params')
+		{ create_group = True
+		, std_in = CreatePipe
+		, std_out = CreatePipe
+		}
+	fileEncoding readh
+	fileEncoding writeh
 	return $ Transferrer
-		{ transferrerRead = myreadh
-		, transferrerWrite = mywriteh
+		{ transferrerRead = readh
+		, transferrerWrite = writeh
 		, transferrerHandle = pid
 		}
-#else
-	error "TODO mkTransferrer not implemented on Windows"
-#endif
 
 {- Checks if a Transferrer is still running. If not, makes a new one. -}
 checkTransferrer :: FilePath -> BatchCommandMaker -> Transferrer -> IO Transferrer

Command/TransferKeys.hs

@@ -16,39 +16,21 @@ import Logs.Location
 import Logs.Transfer
 import qualified Remote
 import Types.Key
-import qualified Option
+
+import GHC.IO.Handle
 
 data TransferRequest = TransferRequest Direction Remote Key AssociatedFile
 
 def :: [Command]
-def = [withOptions options $
-	command "transferkeys" paramNothing seek
+def = [command "transferkeys" paramNothing seek
 	SectionPlumbing "transfers keys"]
 
-options :: [Option]
-options = [readFdOption, writeFdOption]
-
-readFdOption :: Option
-readFdOption = Option.field [] "readfd" paramNumber "read from this fd"
-
-writeFdOption :: Option
-writeFdOption = Option.field [] "writefd" paramNumber "write to this fd"
-
 seek :: [CommandSeek]
-seek = [withField readFdOption convertFd $ \readh ->
-	withField writeFdOption convertFd $ \writeh ->
-	withNothing $ start readh writeh]
+seek = [withNothing start]
 
-convertFd :: Maybe String -> Annex (Maybe Handle)
-convertFd Nothing = return Nothing
-convertFd (Just s) = liftIO $ 
-	case readish s of
-		Nothing -> error "bad fd"
-		Just fd -> Just <$> fdToHandle fd
-
-start :: Maybe Handle -> Maybe Handle -> CommandStart
-start readh writeh = do
-	runRequests (fromMaybe stdin readh) (fromMaybe stdout writeh) runner
+start :: CommandStart
+start = withHandles $ \(readh, writeh) -> do
+	runRequests readh writeh runner
 	stop
   where
 	runner (TransferRequest direction remote key file)
@@ -61,6 +43,21 @@ start readh writeh = do
 		| otherwise = download (Remote.uuid remote) key file forwardRetry $ \p ->
 			getViaTmp key $ \t -> Remote.retrieveKeyFile remote key file t p
 
+{- stdin and stdout are connected with the caller, to be used for
+ - communication with it. But doing a transfer might involve something
+ - that tries to read from stdin, or write to stdout. To avoid that, close
+ - stdin, and duplicate stderr to stdout. Return two new handles
+ - that are duplicates of the original (stdin, stdout). -}
+withHandles :: ((Handle, Handle) -> Annex a) -> Annex a
+withHandles a = do
+	readh <- liftIO $ hDuplicate stdin
+	writeh <- liftIO $ hDuplicate stdout
+	liftIO $ do
+		nullh <- openFile devNull ReadMode
+		nullh `hDuplicateTo` stdin
+		stderr `hDuplicateTo` stdout
+	a (readh, writeh)
+
 runRequests
 	:: Handle
 	-> Handle

GitAnnex.hs

@@ -1,6 +1,6 @@
 {- git-annex main program
  -
- - Copyright 2010 Joey Hess <joey@kitenet.net>
+ - Copyright 2010-2013 Joey Hess <joey@kitenet.net>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
@@ -23,9 +23,7 @@ import qualified Command.Get
 import qualified Command.FromKey
 import qualified Command.DropKey
 import qualified Command.TransferKey
-#ifndef mingw32_HOST_OS
 import qualified Command.TransferKeys
-#endif
 import qualified Command.ReKey
 import qualified Command.Reinject
 import qualified Command.Fix
@@ -129,9 +127,7 @@ cmds = concat
 	, Command.FromKey.def
 	, Command.DropKey.def
 	, Command.TransferKey.def
-#ifndef mingw32_HOST_OS
 	, Command.TransferKeys.def
-#endif
 	, Command.ReKey.def
 	, Command.Fix.def
 	, Command.Fsck.def

Utility/Process.hs

@@ -26,12 +26,12 @@ module Utility.Process (
 	withHandle,
 	withBothHandles,
 	withQuietOutput,
-	withNullHandle,
 	createProcess,
 	startInteractiveProcess,
 	stdinHandle,
 	stdoutHandle,
 	stderrHandle,
+	devNull,
 ) where
 
 import qualified System.Process
@@ -280,20 +280,18 @@ withQuietOutput
 	:: CreateProcessRunner
 	-> CreateProcess
 	-> IO ()
-withQuietOutput creator p = withNullHandle $ \nullh -> do
+withQuietOutput creator p = withFile devNull WriteMode $ \nullh -> do
 	let p' = p
 		{ std_out = UseHandle nullh
 		, std_err = UseHandle nullh
 		}
 	creator p' $ const $ return ()
 
-withNullHandle :: (Handle -> IO a) -> IO a
-withNullHandle = withFile devnull WriteMode
-  where
+devNull :: FilePath
 #ifndef mingw32_HOST_OS
-	devnull = "/dev/null"
+devNull = "/dev/null"
 #else
-	devnull = "NUL"
+devNull = "NUL"
 #endif
 
 {- Extract a desired handle from createProcess's tuple.

doc/todo/windows_support.mdwn

@@ -17,10 +17,6 @@ now! --[[Joey]]
   may be unsafe.
 * `git annex assistant` has not been tested, is probably quite incomplete
   and/or buggy.
-* Assistant is known to not transfer any files.  
-  (transferrer doesn't built yet)  
-  Need a createPipe for windows. See the mkAnonPipe in
-  System.Process source. (cbits/runProcess.c)
 * No XMPP support (needs a lot of C libraries which are available in
   cygwin, but pkg-config does not list them once installed).
 * Doesn't daemonize. Maybe use