git-annex/Remote/Hook.hs

{- A remote that provides hooks to run shell commands.
 -
 - Copyright 2011 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remote.Hook (remote) where

import qualified Data.ByteString.Lazy as L
import qualified Data.Map as M

import Common.Annex
import Types.Remote
import Types.Key
import Types.Creds
import qualified Git
import Config
import Config.Cost
import Annex.Content
import Annex.UUID
import Remote.Helper.Special
import Remote.Helper.Encryptable
import Crypto
import Utility.Metered
import Utility.Env

type Action = String
type HookName = String

remote :: RemoteType
remote = RemoteType {
	typename = "hook",
	enumerate = findSpecialRemotes "hooktype",
	generate = gen,
	setup = hookSetup
}

gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
gen r u c gc = do
	cst <- remoteCost gc expensiveRemoteCost
	return $ Just $ encryptableRemote c
		(storeEncrypted hooktype $ getGpgEncParams (c,gc))
		(retrieveEncrypted hooktype)
		Remote {
			uuid = u,
			cost = cst,
			name = Git.repoDescribe r,
			storeKey = store hooktype,
			retrieveKeyFile = retrieve hooktype,
			retrieveKeyFileCheap = retrieveCheap hooktype,
			removeKey = remove hooktype,
			hasKey = checkPresent r hooktype,
			hasKeyCheap = False,
			whereisKey = Nothing,
			remoteFsck = Nothing,
			repairRepo = Nothing,
			config = c,
			localpath = Nothing,
			repo = r,
			gitconfig = gc,
			readonly = False,
			availability = GloballyAvailable,
			remotetype = remote
		}
  where
	hooktype = fromMaybe (error "missing hooktype") $ remoteAnnexHookType gc

hookSetup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
hookSetup mu _ c = do
	u <- maybe (liftIO genUUID) return mu
	let hooktype = fromMaybe (error "Specify hooktype=") $
		M.lookup "hooktype" c
	c' <- encryptionSetup c
	gitConfigSpecialRemote u c' "hooktype" hooktype
	return (c', u)

hookEnv :: Action -> Key -> Maybe FilePath -> IO (Maybe [(String, String)])
hookEnv action k f = Just <$> mergeenv (fileenv f ++ keyenv)
  where
	mergeenv l = addEntries l <$> getEnvironment
	env s v = ("ANNEX_" ++ s, v)
	keyenv = catMaybes
		[ Just $ env "KEY" (key2file k)
		, Just $ env "ACTION" action
		, env "HASH_1" <$> headMaybe hashbits
		, env "HASH_2" <$> headMaybe (drop 1 hashbits)
		]
	fileenv Nothing = []
	fileenv (Just file) =  [env "FILE" file]
	hashbits = map takeDirectory $ splitPath $ hashDirMixed k

lookupHook :: HookName -> Action -> Annex (Maybe String)
lookupHook hookname action = do
	command <- getConfig (annexConfig hook) ""
	if null command
		then do
			fallback <- getConfig (annexConfig hookfallback) ""
			if null fallback
				then do
					warning $ "missing configuration for " ++ hook ++ " or " ++ hookfallback
					return Nothing
				else return $ Just fallback
		else return $ Just command
  where
	hook = hookname ++ "-" ++ action ++ "-hook"
	hookfallback = hookname ++ "-hook"

runHook :: HookName -> Action -> Key -> Maybe FilePath -> Annex Bool -> Annex Bool
runHook hook action k f a = maybe (return False) run =<< lookupHook hook action
  where
	run command = do
		showOutput -- make way for hook output
		ifM (liftIO $ boolSystemEnv "sh" [Param "-c", Param command] =<< hookEnv action k f)
			( a
			, do
				warning $ hook ++ " hook exited nonzero!"
				return False
			)

store :: HookName -> Key -> AssociatedFile -> MeterUpdate -> Annex Bool
store h k _f _p = sendAnnex k (void $ remove h k) $ \src ->
	runHook h "store" k (Just src) $ return True

storeEncrypted :: HookName -> [CommandParam] -> (Cipher, Key) -> Key -> MeterUpdate -> Annex Bool
storeEncrypted h gpgOpts (cipher, enck) k _p = withTmp enck $ \tmp ->
	sendAnnex k (void $ remove h enck) $ \src -> do
		liftIO $ encrypt gpgOpts cipher (feedFile src) $
			readBytes $ L.writeFile tmp
		runHook h "store" enck (Just tmp) $ return True

retrieve :: HookName -> Key -> AssociatedFile -> FilePath -> MeterUpdate -> Annex Bool
retrieve h k _f d _p = runHook h "retrieve" k (Just d) $ return True

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

retrieveEncrypted :: HookName -> (Cipher, Key) -> Key -> FilePath -> MeterUpdate -> Annex Bool
retrieveEncrypted h (cipher, enck) _ f _p = withTmp enck $ \tmp ->
	runHook h "retrieve" enck (Just tmp) $ liftIO $ catchBoolIO $ do
		decrypt cipher (feedFile tmp) $
			readBytes $ L.writeFile f
		return True

remove :: HookName -> Key -> Annex Bool
remove h k = runHook h "remove" k Nothing $ return True

checkPresent :: Git.Repo -> HookName -> Key -> Annex (Either String Bool)
checkPresent r h k = do
	showAction $ "checking " ++ Git.repoDescribe r
	v <- lookupHook h action
	liftIO $ catchMsgIO $ check v
  where
  	action = "checkpresent"
	findkey s = key2file k `elem` lines s
	check Nothing = error $ action ++ " hook misconfigured"
	check (Just hook) = do
		env <- hookEnv action k Nothing
		findkey <$> readProcessEnv "sh" ["-c", hook] env