git-annex/Remote/Git.hs

{- Standard git remotes.
 -
 - Copyright 2011-2018 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU AGPL version 3 or higher.
 -}

{-# LANGUAGE CPP #-}

module Remote.Git (
	remote,
	configRead,
	repoAvail,
	onLocal,
) where

import Annex.Common
import Annex.Ssh
import Types.Remote
import Types.GitConfig
import qualified Git
import qualified Git.Config
import qualified Git.Construct
import qualified Git.Command
import qualified Git.GCrypt
import qualified Git.Types as Git
import qualified Annex
import Logs.Presence
import Annex.Transfer
import Annex.UUID
import qualified Annex.Content
import qualified Annex.BranchState
import qualified Annex.Branch
import qualified Annex.Url as Url
import Utility.Tmp
import Config
import Config.Cost
import Config.DynamicConfig
import Annex.Init
import Annex.Version
import Types.CleanupActions
import qualified CmdLine.GitAnnexShell.Fields as Fields
import Logs.Location
import Utility.Metered
#ifndef mingw32_HOST_OS
import Utility.CopyFile
#endif
import Utility.Env
import Utility.Batch
import Utility.SimpleProtocol
import Remote.Helper.Git
import Remote.Helper.Messages
import Remote.Helper.Export
import qualified Remote.Helper.Ssh as Ssh
import qualified Remote.GCrypt
import qualified Remote.P2P
import qualified Remote.Helper.P2P as P2PHelper
import P2P.Address
import Annex.Path
import Creds
import Types.NumCopies
import Annex.Action
import Messages.Progress

import Control.Concurrent
import Control.Concurrent.MSampleVar
import qualified Data.Map as M
import Network.URI

remote :: RemoteType
remote = RemoteType
	{ typename = "git"
	, enumerate = list
	, generate = gen
	, setup = gitSetup
	, exportSupported = exportUnsupported
	}

list :: Bool -> Annex [Git.Repo]
list autoinit = do
	c <- fromRepo Git.config
	rs <- mapM (tweakurl c) =<< Annex.getGitRemotes
	mapM (configRead autoinit) rs
  where
	annexurl n = "remote." ++ n ++ ".annexurl"
	tweakurl c r = do
		let n = fromJust $ Git.remoteName r
		case M.lookup (annexurl n) c of
			Nothing -> return r
			Just url -> inRepo $ \g ->
				Git.Construct.remoteNamed n $
					Git.Construct.fromRemoteLocation url g

{- Git remotes are normally set up using standard git command, not
 - git-annex initremote and enableremote.
 -
 - For initremote, the git remote must already be set up, and have a uuid.
 - Initremote simply remembers its location.
 -
 - enableremote simply sets up a git remote using the stored location.
 - No attempt is made to make the remote be accessible via ssh key setup,
 - etc.
 -}
gitSetup :: SetupStage -> Maybe UUID -> Maybe CredPair -> RemoteConfig -> RemoteGitConfig -> Annex (RemoteConfig, UUID)
gitSetup Init mu _ c _ = do
	let location = fromMaybe (giveup "Specify location=url") $
		Url.parseURIRelaxed =<< M.lookup "location" c
	rs <- Annex.getGitRemotes
	u <- case filter (\r -> Git.location r == Git.Url location) rs of
		[r] -> getRepoUUID r
		[] -> giveup "could not find existing git remote with specified location"
		_ -> giveup "found multiple git remotes with specified location"
	if isNothing mu || mu == Just u
		then return (c, u)
		else error "git remote did not have specified uuid"
gitSetup (Enable _) (Just u) _ c _ = do
	inRepo $ Git.Command.run
		[ Param "remote"
		, Param "add"
		, Param $ fromMaybe (giveup "no name") (M.lookup "name" c)
		, Param $ fromMaybe (giveup "no location") (M.lookup "location" c)
		]
	return (c, u)
gitSetup (Enable _) Nothing _ _ _ = error "unable to enable git remote with no specified uuid"

{- It's assumed to be cheap to read the config of non-URL remotes, so this is
 - done each time git-annex is run in a way that uses remotes, unless
 - annex-checkuuid is false.
 -
 - Conversely, the config of an URL remote is only read when there is no
 - cached UUID value. -}
configRead :: Bool -> Git.Repo -> Annex Git.Repo
configRead autoinit r = do
	gc <- Annex.getRemoteGitConfig r
	u <- getRepoUUID r
	annexignore <- liftIO $ getDynamicConfig (remoteAnnexIgnore gc)
	case (repoCheap r, annexignore, u) of
		(_, True, _) -> return r
		(True, _, _)
			| remoteAnnexCheckUUID gc -> tryGitConfigRead autoinit r
			| otherwise -> return r
		(False, _, NoUUID) -> tryGitConfigRead autoinit r
		_ -> return r

gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
gen r u c gc
	| Git.GCrypt.isEncrypted r = Remote.GCrypt.chainGen r u c gc
	| otherwise = case repoP2PAddress r of
		Nothing -> do
			st <- mkState r u gc
			go st <$> remoteCost gc defcst
		Just addr -> Remote.P2P.chainGen addr r u c gc
  where
	defcst = if repoCheap r then cheapRemoteCost else expensiveRemoteCost
	go st cst = Just new
	  where
		new = Remote 
			{ uuid = u
			, cost = cst
			, name = Git.repoDescribe r
			, storeKey = copyToRemote new st
			, retrieveKeyFile = copyFromRemote new st
			, retrieveKeyFileCheap = copyFromRemoteCheap new st
			, removeKey = dropKey new st
			, lockContent = Just (lockKey new st)
			, checkPresent = inAnnex new st
			, checkPresentCheap = repoCheap r
			, exportActions = exportUnsupported
			, whereisKey = Nothing
			, remoteFsck = if Git.repoIsUrl r
				then Nothing
				else Just $ fsckOnRemote r
			, repairRepo = if Git.repoIsUrl r
				then Nothing
				else Just $ repairRemote r
			, config = c
			, localpath = localpathCalc r
			, repo = r
			, gitconfig = gc { remoteGitConfig = extractGitConfig r }
			, readonly = Git.repoIsHttp r
			, availability = availabilityCalc r
			, remotetype = remote
			, mkUnavailable = unavailable r u c gc
			, getInfo = gitRepoInfo new
			, claimUrl = Nothing
			, checkUrl = Nothing
			}

unavailable :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
unavailable r u c gc = gen r' u c gc
  where
	r' = case Git.location r of
		Git.Local { Git.gitdir = d } ->
			r { Git.location = Git.LocalUnknown d }
		Git.Url url -> case uriAuthority url of
			Just auth -> 
				let auth' = auth { uriRegName = "!dne!" }
				in r { Git.location = Git.Url (url { uriAuthority = Just auth' })}
			Nothing -> r { Git.location = Git.Unknown }
		_ -> r -- already unavailable

{- Checks relatively inexpensively if a repository is available for use. -}
repoAvail :: Git.Repo -> Annex Bool
repoAvail r 
	| Git.repoIsHttp r = return True
	| Git.GCrypt.isEncrypted r = do
		g <- gitRepo
		liftIO $ do
			er <- Git.GCrypt.encryptedRemote g r
			if Git.repoIsLocal er || Git.repoIsLocalUnknown er
				then catchBoolIO $
					void (Git.Config.read er) >> return True
				else return True
	| Git.repoIsUrl r = return True
	| Git.repoIsLocalUnknown r = return False
	| otherwise = liftIO $ isJust <$> catchMaybeIO (Git.Config.read r)

{- Tries to read the config for a specified remote, updates state, and
 - returns the updated repo. -}
tryGitConfigRead :: Bool -> Git.Repo -> Annex Git.Repo
tryGitConfigRead autoinit r 
	| haveconfig r = return r -- already read
	| Git.repoIsSsh r = store $ do
		v <- Ssh.onRemote NoConsumeStdin r
			(pipedconfig, return (Left $ giveup "configlist failed"))
			"configlist" [] configlistfields
		case v of
			Right r'
				| haveconfig r' -> return r'
				| otherwise -> configlist_failed
			Left _ -> configlist_failed
	| Git.repoIsHttp r = store geturlconfig
	| Git.GCrypt.isEncrypted r = handlegcrypt =<< getConfigMaybe (remoteConfig r "uuid")
	| Git.repoIsUrl r = return r
	| otherwise = store $ liftIO $ 
		readlocalannexconfig `catchNonAsync` (const $ return r)
  where
	haveconfig = not . M.null . Git.config

	pipedconfig cmd params = do
		v <- Git.Config.fromPipe r cmd params
		case v of
			Right (r', val) -> do
				unless (isUUIDConfigured r' || null val) $ do
					warningIO $ "Failed to get annex.uuid configuration of repository " ++ Git.repoDescribe r
					warningIO $ "Instead, got: " ++ show val
					warningIO $ "This is unexpected; please check the network transport!"
				return $ Right r'
			Left l -> return $ Left l

	geturlconfig = do
		uo <- Url.getUrlOptions
		v <- liftIO $ withTmpFile "git-annex.tmp" $ \tmpfile h -> do
			hClose h
			let url = Git.repoLocation r ++ "/config"
			ifM (Url.downloadQuiet url tmpfile uo)
				( Just <$> pipedconfig "git" [Param "config", Param "--null", Param "--list", Param "--file", File tmpfile]
				, return Nothing
				)
		case v of
			Just (Right r') -> do
				-- Cache when http remote is not bare for
				-- optimisation.
				unless (Git.Config.isBare r') $
					setremote setRemoteBare False
				return r'
			_ -> do
				set_ignore "not usable by git-annex" False
				return r

	store = observe $ \r' -> do
		l <- Annex.getGitRemotes
		let rs = exchange l r'
		Annex.changeState $ \s -> s { Annex.gitremotes = Just rs }

	exchange [] _ = []
	exchange (old:ls) new
		| Git.remoteName old == Git.remoteName new =
			new : exchange ls new
		| otherwise =
			old : exchange ls new

	{- Is this remote just not available, or does
	 - it not have git-annex-shell?
	 - Find out by trying to fetch from the remote. -}
	configlist_failed = case Git.remoteName r of
		Nothing -> return r
		Just n -> do
			whenM (inRepo $ Git.Command.runBool [Param "fetch", Param "--quiet", Param n]) $ do
				set_ignore "does not have git-annex installed" True
			return r
	
	set_ignore msg longmessage = do
		case Git.remoteName r of
			Nothing -> noop
			Just n -> do
				warning $ "Remote " ++ n ++ " " ++ msg ++ "; setting annex-ignore"
				when longmessage $
					warning $ "This could be a problem with the git-annex installation on the remote. Please make sure that git-annex-shell is available in PATH when you ssh into the remote. Once you have fixed the git-annex installation, run: git annex enableremote " ++ n
		setremote setRemoteIgnore True
	
	setremote setter v = case Git.remoteName r of
		Nothing -> noop
		Just _ -> setter r v
	
	handlegcrypt Nothing = return r
	handlegcrypt (Just _cacheduuid) = do
		-- Generate UUID from the gcrypt-id
		g <- gitRepo
		case Git.GCrypt.remoteRepoId g (Git.remoteName r) of
			Nothing -> return r
			Just v -> store $ liftIO $ setUUID r $
				genUUIDInNameSpace gCryptNameSpace v

	{- The local repo may not yet be initialized, so try to initialize
	 - it if allowed. However, if that fails, still return the read
	 - git config. -}
	readlocalannexconfig = do
		let check = do
			Annex.BranchState.disableUpdate
			void $ tryNonAsync $ ensureInitialized
			Annex.getState Annex.repo
		s <- Annex.new r
		Annex.eval s $ check `finally` stopCoProcesses
		
	configlistfields = if autoinit
		then [(Fields.autoInit, "1")]
		else []

{- Checks if a given remote has the content for a key in its annex. -}
inAnnex :: Remote -> State -> Key -> Annex Bool
inAnnex rmt (State connpool duc) key
	| Git.repoIsHttp r = checkhttp
	| Git.repoIsUrl r = checkremote
	| otherwise = checklocal
  where
	r = repo rmt
	checkhttp = do
		showChecking r
		ifM (Url.withUrlOptions $ \uo -> anyM (\u -> Url.checkBoth u (keySize key) uo) (keyUrls rmt key))
			( return True
			, giveup "not found"
			)
	checkremote = 
		let fallback = Ssh.inAnnex r key
		in P2PHelper.checkpresent (Ssh.runProto rmt connpool (cantCheck rmt) fallback) key
	checklocal = ifM duc
		( guardUsable r (cantCheck r) $
			maybe (cantCheck r) return
				=<< onLocalFast rmt (Annex.Content.inAnnexSafe key)
		, cantCheck r
		)

keyUrls :: Remote -> Key -> [String]
keyUrls r key = map tourl locs'
  where
	tourl l = Git.repoLocation (repo r) ++ "/" ++ l
	-- If the remote is known to not be bare, try the hash locations
	-- used for non-bare repos first, as an optimisation.
	locs
		| remoteAnnexBare remoteconfig == Just False = reverse (annexLocations cfg key)
		| otherwise = annexLocations cfg key
#ifndef mingw32_HOST_OS
	locs' = locs
#else
	locs' = map (replace "\\" "/") locs
#endif
	remoteconfig = gitconfig r
	cfg = remoteGitConfig remoteconfig

dropKey :: Remote -> State -> Key -> Annex Bool
dropKey r (State connpool duc) key
	| not $ Git.repoIsUrl (repo r) = ifM duc
		( guardUsable (repo r) (return False) $
			commitOnCleanup r $ onLocalFast r $ do
				ensureInitialized
				whenM (Annex.Content.inAnnex key) $ do
					Annex.Content.lockContentForRemoval key $ \lock -> do
						Annex.Content.removeAnnex lock
						logStatus key InfoMissing
					Annex.Content.saveState True
				return True
		, return False
		)
	| Git.repoIsHttp (repo r) = giveup "dropping from http remote not supported"
	| otherwise = commitOnCleanup r $ do
		let fallback = Ssh.dropKey (repo r) key
		P2PHelper.remove (Ssh.runProto r connpool False fallback) key

lockKey :: Remote -> State -> Key -> (VerifiedCopy -> Annex r) -> Annex r
lockKey r (State connpool duc) key callback
	| not $ Git.repoIsUrl (repo r) = ifM duc
		( guardUsable (repo r) failedlock $ do
			inorigrepo <- Annex.makeRunner
			-- Lock content from perspective of remote,
			-- and then run the callback in the original
			-- annex monad, not the remote's.
			onLocalFast r $ 
				Annex.Content.lockContentShared key $
					liftIO . inorigrepo . callback
		, failedlock
		)
	| Git.repoIsSsh (repo r) = do
		showLocking r
		let withconn = Ssh.withP2PSshConnection r connpool fallback
		P2PHelper.lock withconn Ssh.runProtoConn (uuid r) key callback
	| otherwise = failedlock
  where
	fallback = do
		Just (cmd, params) <- Ssh.git_annex_shell ConsumeStdin
			(repo r) "lockcontent"
			[Param $ key2file key] []
		(Just hin, Just hout, Nothing, p) <- liftIO $ 
			withFile devNull WriteMode $ \nullh ->
				createProcess $
					 (proc cmd (toCommand params))
						{ std_in = CreatePipe
						, std_out = CreatePipe
						, std_err = UseHandle nullh
						}
		v <- liftIO $ tryIO $ getProtocolLine hout
		let signaldone = void $ tryNonAsync $ liftIO $ mapM_ tryNonAsync
			[ hPutStrLn hout ""
			, hFlush hout
			, hClose hin
			, hClose hout
			, void $ waitForProcess p
			]
		let checkexited = not . isJust <$> getProcessExitCode p
		case v of
			Left _exited -> do
				showNote "lockcontent failed"
				liftIO $ do
					hClose hin
					hClose hout
					void $ waitForProcess p
				failedlock
			Right l 
				| l == Just Ssh.contentLockedMarker -> bracket_
					noop
					signaldone 
					(withVerifiedCopy LockedCopy r checkexited callback)
				| otherwise -> do
					showNote "lockcontent failed"
					signaldone
					failedlock
	failedlock = giveup "can't lock content"

{- Tries to copy a key's content from a remote's annex to a file. -}
copyFromRemote :: Remote -> State -> Key -> AssociatedFile -> FilePath -> MeterUpdate -> Annex (Bool, Verification)
copyFromRemote = copyFromRemote' False

copyFromRemote' :: Bool -> Remote -> State -> Key -> AssociatedFile -> FilePath -> MeterUpdate -> Annex (Bool, Verification)
copyFromRemote' forcersync r (State connpool _) key file dest meterupdate
	| Git.repoIsHttp (repo r) = unVerified $
		Annex.Content.downloadUrl key meterupdate (keyUrls r key) dest
	| not $ Git.repoIsUrl (repo r) = guardUsable (repo r) (unVerified (return False)) $ do
		params <- Ssh.rsyncParams r Download
		u <- getUUID
		hardlink <- wantHardLink
		-- run copy from perspective of remote
		onLocalFast r $ do
			ensureInitialized
			v <- Annex.Content.prepSendAnnex key
			case v of
				Nothing -> return (False, UnVerified)
				Just (object, checksuccess) -> do
					copier <- mkCopier hardlink params
					runTransfer (Transfer Download u key)
						file forwardRetry
						(\p -> copier object dest (combineMeterUpdate p meterupdate) checksuccess)
	| Git.repoIsSsh (repo r) = if forcersync
		then fallback meterupdate
		else P2PHelper.retrieve
			(\p -> Ssh.runProto r connpool (False, UnVerified) (fallback p))
			key file dest meterupdate
	| otherwise = giveup "copying from non-ssh, non-http remote not supported"
  where
	fallback p = unVerified $ feedprogressback $ \p' -> do
		oh <- mkOutputHandlerQuiet
		Ssh.rsyncHelper oh (Just (combineMeterUpdate p' p))
			=<< Ssh.rsyncParamsRemote False r Download key dest file
	{- Feed local rsync's progress info back to the remote,
	 - by forking a feeder thread that runs
	 - git-annex-shell transferinfo at the same time
	 - git-annex-shell sendkey is running.
	 -
	 - To avoid extra password prompts, this is only done when ssh
	 - connection caching is supported.
	 - Note that it actually waits for rsync to indicate
	 - progress before starting transferinfo, in order
	 - to ensure ssh connection caching works and reuses 
	 - the connection set up for the sendkey.
	 -
	 - Also note that older git-annex-shell does not support
	 - transferinfo, so stderr is dropped and failure ignored.
	 -}
	feedprogressback a = ifM (isJust <$> sshCacheDir)
		( feedprogressback' a
		, a $ const noop
		)
	feedprogressback' a = do
		u <- getUUID
		let AssociatedFile afile = file
		let fields = (Fields.remoteUUID, fromUUID u)
			: maybe [] (\f -> [(Fields.associatedFile, f)]) afile
		Just (cmd, params) <- Ssh.git_annex_shell ConsumeStdin
			(repo r) "transferinfo" 
			[Param $ key2file key] fields
		v <- liftIO (newEmptySV :: IO (MSampleVar Integer))
		pidv <- liftIO $ newEmptyMVar
		tid <- liftIO $ forkIO $ void $ tryIO $ do
			bytes <- readSV v
			p <- createProcess $
				 (proc cmd (toCommand params))
					{ std_in = CreatePipe
					, std_err = CreatePipe
					}
			putMVar pidv (processHandle p)
			hClose $ stderrHandle p
			let h = stdinHandle p
			let send b = do
				hPrint h b
				hFlush h
			send bytes
			forever $
				send =<< readSV v
		let feeder = \n -> do
			meterupdate n
			writeSV v (fromBytesProcessed n)

		-- It can easily take 0.3 seconds to clean up after
		-- the transferinfo, and all that's involved is shutting
		-- down the process and associated thread cleanly. So,
		-- do it in the background.
		let cleanup = forkIO $ do
			void $ tryIO $ killThread tid
			void $ tryNonAsync $
				maybe noop (void . waitForProcess)
					=<< tryTakeMVar pidv
		bracketIO noop (const cleanup) (const $ a feeder)

copyFromRemoteCheap :: Remote -> State -> Key -> AssociatedFile -> FilePath -> Annex Bool
#ifndef mingw32_HOST_OS
copyFromRemoteCheap r st key af file
	| not $ Git.repoIsUrl (repo r) = guardUsable (repo r) (return False) $ liftIO $ do
		loc <- gitAnnexLocation key (repo r) $
			remoteGitConfig $ gitconfig r
		ifM (doesFileExist loc)
			( do
				absloc <- absPath loc
				catchBoolIO $ do
					createSymbolicLink absloc file
					return True
			, return False
			)
	| Git.repoIsSsh (repo r) =
		ifM (Annex.Content.preseedTmp key file)
			( fst <$> copyFromRemote' True r st key af file nullMeterUpdate
			, return False
			)
	| otherwise = return False
#else
copyFromRemoteCheap _ _ _ _ _ = return False
#endif

{- Tries to copy a key's content to a remote's annex. -}
copyToRemote :: Remote -> State -> Key -> AssociatedFile -> MeterUpdate -> Annex Bool
copyToRemote r (State connpool duc) key file meterupdate
	| not $ Git.repoIsUrl (repo r) = ifM duc
		( guardUsable (repo r) (return False) $ commitOnCleanup r $
			copylocal =<< Annex.Content.prepSendAnnex key
		, return False
		)
	| Git.repoIsSsh (repo r) = commitOnCleanup r $
		P2PHelper.store
			(\p -> Ssh.runProto r connpool False (copyremotefallback p))
			key file meterupdate
		
	| otherwise = giveup "copying to non-ssh repo not supported"
  where
	copylocal Nothing = return False
	copylocal (Just (object, checksuccess)) = do
		-- The checksuccess action is going to be run in
		-- the remote's Annex, but it needs access to the local
		-- Annex monad's state.
		checksuccessio <- Annex.withCurrentState checksuccess
		params <- Ssh.rsyncParams r Upload
		u <- getUUID
		hardlink <- wantHardLink
		-- run copy from perspective of remote
		onLocalFast r $ ifM (Annex.Content.inAnnex key)
			( return True
			, do
				ensureInitialized
				copier <- mkCopier hardlink params
				let verify = Annex.Content.RemoteVerify r
				runTransfer (Transfer Download u key) file forwardRetry $ \p ->
					let p' = combineMeterUpdate meterupdate p
					in Annex.Content.saveState True `after`
						Annex.Content.getViaTmp verify key
							(\dest -> copier object dest p' (liftIO checksuccessio))
			)
	copyremotefallback p = Annex.Content.sendAnnex key noop $ \object -> do
		-- This is too broad really, but recvkey normally
		-- verifies content anyway, so avoid complicating
		-- it with a local sendAnnex check and rollback.
		unlocked <- isDirect <||> versionSupportsUnlockedPointers
		oh <- mkOutputHandlerQuiet
		Ssh.rsyncHelper oh (Just p)
			=<< Ssh.rsyncParamsRemote unlocked r Upload key object file

fsckOnRemote :: Git.Repo -> [CommandParam] -> Annex (IO Bool)
fsckOnRemote r params
	| Git.repoIsUrl r = do
		s <- Ssh.git_annex_shell NoConsumeStdin r "fsck" params []
		return $ case s of
			Nothing -> return False
			Just (c, ps) -> batchCommand c ps
	| otherwise = return $ do
		program <- programPath
		r' <- Git.Config.read r
		environ <- getEnvironment
		let environ' = addEntries 
			[ ("GIT_WORK_TREE", Git.repoPath r')
			, ("GIT_DIR", Git.localGitDir r')
			] environ
		batchCommandEnv program (Param "fsck" : params) (Just environ')

{- The passed repair action is run in the Annex monad of the remote. -}
repairRemote :: Git.Repo -> Annex Bool -> Annex (IO Bool)
repairRemote r a = return $ do
	s <- Annex.new r
	Annex.eval s $ do
		Annex.BranchState.disableUpdate
		ensureInitialized
		a `finally` stopCoProcesses

{- Runs an action from the perspective of a local remote.
 -
 - The AnnexState is cached for speed and to avoid resource leaks.
 - However, coprocesses are stopped after each call to avoid git
 - processes hanging around on removable media.
 -}
onLocal :: Remote -> Annex a -> Annex a
onLocal r a = do
	m <- Annex.getState Annex.remoteannexstate
	go =<< maybe
		(liftIO $ Annex.new $ repo r)
		return
		(M.lookup (uuid r) m)
  where
	cache st = Annex.changeState $ \s -> s
		{ Annex.remoteannexstate = M.insert (uuid r) st (Annex.remoteannexstate s) }
	go st = do
		curro <- Annex.getState Annex.output
		(ret, st') <- liftIO $ Annex.run (st { Annex.output = curro }) $
			a `finally` stopCoProcesses
		cache st'
		return ret

{- Faster variant of onLocal.
 -
 - The repository's git-annex branch is not updated, as an optimisation.
 - No caller of onLocalFast can query data from the branch and be ensured
 - it gets the most current value. Caller of onLocalFast can make changes
 - to the branch, however.
 -}
onLocalFast :: Remote -> Annex a -> Annex a
onLocalFast r a = onLocal r $ Annex.BranchState.disableUpdate >> a

{- Copys a file with rsync unless both locations are on the same
 - filesystem. Then cp could be faster. -}
rsyncOrCopyFile :: [CommandParam] -> FilePath -> FilePath -> MeterUpdate -> Annex Bool
rsyncOrCopyFile rsyncparams src dest p =
#ifdef mingw32_HOST_OS
	dorsync
  where
#else
	ifM (sameDeviceIds src dest) (docopy, dorsync)
  where
	sameDeviceIds a b = (==) <$> getDeviceId a <*> getDeviceId b
	getDeviceId f = deviceID <$> liftIO (getFileStatus $ parentDir f)
	docopy = liftIO $ watchFileSize dest p $
		copyFileExternal CopyTimeStamps src dest
#endif
	dorsync = do
		oh <- mkOutputHandler
		Ssh.rsyncHelper oh (Just p) $
			rsyncparams ++ [File src, File dest]

commitOnCleanup :: Remote -> Annex a -> Annex a
commitOnCleanup r a = go `after` a
  where
	go = Annex.addCleanup (RemoteCleanup $ uuid r) cleanup
	cleanup
		| not $ Git.repoIsUrl (repo r) = onLocalFast r $
			doQuietSideAction $
				Annex.Branch.commit "update"
		| otherwise = void $ do
			Just (shellcmd, shellparams) <-
				Ssh.git_annex_shell NoConsumeStdin
					(repo r) "commit" [] []
			
			-- Throw away stderr, since the remote may not
			-- have a new enough git-annex shell to
			-- support committing.
			liftIO $ catchMaybeIO $
				withQuietOutput createProcessSuccess $
					proc shellcmd $
						toCommand shellparams

wantHardLink :: Annex Bool
wantHardLink = (annexHardLink <$> Annex.getGitConfig)
	-- Not direct mode files because they can be modified at any time.
	<&&> (not <$> isDirect)
	-- Not unlocked files that are hard linked in the work tree,
	-- because they can be modified at any time.
	<&&> (not <$> annexThin <$> Annex.getGitConfig)

-- Copies from src to dest, updating a meter. If the copy finishes
-- successfully, calls a final check action, which must also succeed, or
-- returns false.
--
-- If either the remote or local repository wants to use hard links,
-- the copier will do so (falling back to copying if a hard link cannot be
-- made).
--
-- When a hard link is created, returns Verified; the repo being linked
-- from is implicitly trusted, so no expensive verification needs to be
-- done.
type Copier = FilePath -> FilePath -> MeterUpdate -> Annex Bool -> Annex (Bool, Verification)

mkCopier :: Bool -> [CommandParam] -> Annex Copier
mkCopier remotewanthardlink rsyncparams = do
	let copier = \src dest p check -> unVerified $
		rsyncOrCopyFile rsyncparams src dest p <&&> check
	localwanthardlink <- wantHardLink
	let linker = \src dest -> createLink src dest >> return True
	ifM (pure (remotewanthardlink || localwanthardlink) <&&> not <$> isDirect)
		( return $ \src dest p check ->
			ifM (liftIO (catchBoolIO (linker src dest)))
				( return (True, Verified)
				, copier src dest p check
				)
		, return copier
		)

data State = State Ssh.P2PSshConnectionPool DeferredUUIDCheck

mkState :: Git.Repo -> UUID -> RemoteGitConfig -> Annex State
mkState r u gc = State
	<$> Ssh.mkP2PSshConnectionPool
	<*> mkDeferredUUIDCheck r u gc

{- Normally the UUID of a local repository is checked at startup,
 - but annex-checkuuid config can prevent that. To avoid getting
 - confused, a deferred check is done just before the repository
 - is used.
 - This returns False when the repository UUID is not as expected. -}
type DeferredUUIDCheck = Annex Bool

mkDeferredUUIDCheck :: Git.Repo -> UUID -> RemoteGitConfig -> Annex DeferredUUIDCheck
mkDeferredUUIDCheck r u gc
	| remoteAnnexCheckUUID gc = return (return True)
	| otherwise = do
		v <- liftIO newEmptyMVar
		return $ ifM (liftIO $ isEmptyMVar v)
			( do
				r' <- tryGitConfigRead False r
				u' <- getRepoUUID r'
				let ok = u' == u
				void $ liftIO $ tryPutMVar v ok
				unless ok $
					warning $ Git.repoDescribe r ++ " is not the expected repository. The remote's annex-checkuuid configuration prevented noticing the change until now."
				return ok
			, liftIO $ readMVar v
			)