git-annex/Remote/Bup.hs

{- Using bup as a remote.
 -
 - Copyright 2011 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remote.Bup (remote) where

import qualified Data.ByteString.Lazy.Char8 as L
import qualified Data.Map as M
import System.Process

import Common.Annex
import Types.Remote
import qualified Git
import qualified Git.Command
import qualified Git.Config
import qualified Git.Construct
import Config
import Remote.Helper.Ssh
import Remote.Helper.Special
import Remote.Helper.Encryptable
import Crypto

type BupRepo = String

remote :: RemoteType
remote = RemoteType {
	typename = "bup",
	enumerate = findSpecialRemotes "buprepo",
	generate = gen,
	setup = bupSetup
}

gen :: Git.Repo -> UUID -> Maybe RemoteConfig -> Annex Remote
gen r u c = do
	buprepo <- getConfig r "buprepo" (error "missing buprepo")
	cst <- remoteCost r (if bupLocal buprepo then semiCheapRemoteCost else expensiveRemoteCost)
	bupr <- liftIO $ bup2GitRemote buprepo
	(u', bupr') <- getBupUUID bupr u
	
	return $ encryptableRemote c
		(storeEncrypted r buprepo)
		(retrieveEncrypted buprepo)
		Remote {
			uuid = u',
			cost = cst,
			name = Git.repoDescribe r,
 			storeKey = store r buprepo,
			retrieveKeyFile = retrieve buprepo,
			retrieveKeyFileCheap = retrieveCheap buprepo,
			removeKey = remove,
			hasKey = checkPresent r bupr',
			hasKeyCheap = bupLocal buprepo,
			whereisKey = Nothing,
			config = c,
			repo = r,
			remotetype = remote
		}

bupSetup :: UUID -> RemoteConfig -> Annex RemoteConfig
bupSetup u c = do
	-- verify configuration is sane
	let buprepo = fromMaybe (error "Specify buprepo=") $
		M.lookup "buprepo" c
	c' <- encryptionSetup c

	-- bup init will create the repository.
	-- (If the repository already exists, bup init again appears safe.)
	showAction "bup init"
	unlessM (bup "init" buprepo []) $ error "bup init failed"

	storeBupUUID u buprepo

	-- The buprepo is stored in git config, as well as this repo's
	-- persistant state, so it can vary between hosts.
	gitConfigSpecialRemote u c' "buprepo" buprepo

	return c'

bupParams :: String -> BupRepo -> [CommandParam] -> [CommandParam]
bupParams command buprepo params = 
	Param command : [Param "-r", Param buprepo] ++ params

bup :: String -> BupRepo -> [CommandParam] -> Annex Bool
bup command buprepo params = do
	showOutput -- make way for bup output
	liftIO $ boolSystem "bup" $ bupParams command buprepo params

pipeBup :: [CommandParam] -> Maybe Handle -> Maybe Handle -> IO Bool
pipeBup params inh outh = do
	p <- runProcess "bup" (toCommand params)
		Nothing Nothing inh outh Nothing
	ok <- waitForProcess p
	case ok of
		ExitSuccess -> return True
		_ -> return False

bupSplitParams :: Git.Repo -> BupRepo -> Key -> CommandParam -> Annex [CommandParam]
bupSplitParams r buprepo k src = do
	o <- getConfig r "bup-split-options" ""
	let os = map Param $ words o
	showOutput -- make way for bup output
	return $ bupParams "split" buprepo 
		(os ++ [Param "-n", Param (show k), src])

store :: Git.Repo -> BupRepo -> Key -> Annex Bool
store r buprepo k = do
	src <- inRepo $ gitAnnexLocation k
	params <- bupSplitParams r buprepo k (File src)
	liftIO $ boolSystem "bup" params

storeEncrypted :: Git.Repo -> BupRepo -> (Cipher, Key) -> Key -> Annex Bool
storeEncrypted r buprepo (cipher, enck) k = do
	src <- inRepo $ gitAnnexLocation k
	params <- bupSplitParams r buprepo enck (Param "-")
	liftIO $ catchBoolIO $
		withEncryptedHandle cipher (L.readFile src) $ \h ->
			pipeBup params (Just h) Nothing

retrieve :: BupRepo -> Key -> FilePath -> Annex Bool
retrieve buprepo k f = do
	let params = bupParams "join" buprepo [Param $ show k]
	liftIO $ catchBoolIO $ do
		tofile <- openFile f WriteMode
		pipeBup params Nothing (Just tofile)

retrieveCheap :: BupRepo -> Key -> FilePath -> Annex Bool
retrieveCheap _ _ _ = return False

retrieveEncrypted :: BupRepo -> (Cipher, Key) -> Key -> FilePath -> Annex Bool
retrieveEncrypted buprepo (cipher, enck) _ f = do
	let params = bupParams "join" buprepo [Param $ show enck]
	liftIO $ catchBoolIO $ do
		(pid, h) <- hPipeFrom "bup" $ toCommand params
		withDecryptedContent cipher (L.hGetContents h) $ L.writeFile f
		forceSuccess pid
		return True

remove :: Key -> Annex Bool
remove _ = do
	warning "content cannot be removed from bup remote"
	return False

{- Bup does not provide a way to tell if a given dataset is present
 - in a bup repository. One way it to check if the git repository has
 - a branch matching the name (as created by bup split -n).
 -}
checkPresent :: Git.Repo -> Git.Repo -> Key -> Annex (Either String Bool)
checkPresent r bupr k
	| Git.repoIsUrl bupr = do
		showAction $ "checking " ++ Git.repoDescribe r
		ok <- onBupRemote bupr boolSystem "git" params
		return $ Right ok
	| otherwise = liftIO $ catchMsgIO $
		boolSystem "git" $ Git.Command.gitCommandLine params bupr
	where
		params = 
			[ Params "show-ref --quiet --verify"
			, Param $ "refs/heads/" ++ show k]

{- Store UUID in the annex.uuid setting of the bup repository. -}
storeBupUUID :: UUID -> BupRepo -> Annex ()
storeBupUUID u buprepo = do
	r <- liftIO $ bup2GitRemote buprepo
	if Git.repoIsUrl r
		then do
			showAction "storing uuid"
			unlessM (onBupRemote r boolSystem "git"
				[Params $ "config annex.uuid " ++ v]) $
					error "ssh failed"
		else liftIO $ do
			r' <- Git.Config.read r
			let olduuid = Git.Config.get "annex.uuid" "" r'
			when (olduuid == "") $
				Git.Command.run "config"
					[Param "annex.uuid", Param v] r'
	where
		v = fromUUID u

onBupRemote :: Git.Repo -> (FilePath -> [CommandParam] -> IO a) -> FilePath -> [CommandParam] -> Annex a
onBupRemote r a command params = do
	let dir = shellEscape (Git.workTree r)
	sshparams <- sshToRepo r [Param $
			"cd " ++ dir ++ " && " ++ unwords (command : toCommand params)]
	liftIO $ a "ssh" sshparams

{- Allow for bup repositories on removable media by checking
 - local bup repositories to see if they are available, and getting their
 - uuid (which may be different from the stored uuid for the bup remote).
 -
 - If a bup repository is not available, returns NoUUID.
 - This will cause checkPresent to indicate nothing from the bup remote
 - is known to be present.
 -
 - Also, returns a version of the repo with config read, if it is local.
 -}
getBupUUID :: Git.Repo -> UUID -> Annex (UUID, Git.Repo)
getBupUUID r u
	| Git.repoIsUrl r = return (u, r)
	| otherwise = liftIO $ do
		ret <- tryIO $ Git.Config.read r
		case ret of
			Right r' -> return (toUUID $ Git.Config.get "annex.uuid" "" r', r')
			Left _ -> return (NoUUID, r)

{- Converts a bup remote path spec into a Git.Repo. There are some
 - differences in path representation between git and bup. -}
bup2GitRemote :: BupRepo -> IO Git.Repo
bup2GitRemote "" = do
	-- bup -r "" operates on ~/.bup
	h <- myHomeDir
	Git.Construct.fromAbsPath $ h </> ".bup"
bup2GitRemote r
	| bupLocal r = 
		if "/" `isPrefixOf` r
			then Git.Construct.fromAbsPath r
			else error "please specify an absolute path"
	| otherwise = Git.Construct.fromUrl $ "ssh://" ++ host ++ slash dir
		where
			bits = split ":" r
			host = Prelude.head bits
			dir = join ":" $ drop 1 bits
			-- "host:~user/dir" is not supported specially by bup;
			-- "host:dir" is relative to the home directory;
			-- "host:" goes in ~/.bup
			slash d
				| null d = "/~/.bup"
				| "/" `isPrefixOf` d = d
				| otherwise = "/~/" ++ d

bupLocal :: BupRepo -> Bool
bupLocal = notElem ':'