git-annex/Limit.hs

{- user-specified limits on files to act on
 -
 - Copyright 2011,2012 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Limit where

import Text.Regex.PCRE.Light.Char8
import System.Path.WildMatch
import Data.Time.Clock.POSIX
import qualified Data.Set as S

import Common.Annex
import qualified Annex
import qualified Utility.Matcher
import qualified Remote
import qualified Backend
import Annex.Content
import Annex.UUID
import Logs.Trust
import Types.TrustLevel
import Types.Key
import Logs.Group
import Utility.HumanTime
import Utility.DataUnits

type MatchFiles = AssumeNotPresent -> FilePath -> Annex Bool
type MkLimit = String -> Either String MatchFiles
type AssumeNotPresent = S.Set UUID

{- Checks if there are user-specified limits. -}
limited :: Annex Bool
limited = (not . Utility.Matcher.matchesAny) <$> getMatcher'

{- Gets a matcher for the user-specified limits. The matcher is cached for
 - speed; once it's obtained the user-specified limits can't change. -}
getMatcher :: Annex (FilePath -> Annex Bool)
getMatcher = Utility.Matcher.matchM <$> getMatcher'

getMatcher' :: Annex (Utility.Matcher.Matcher (FilePath -> Annex Bool))
getMatcher' = do
	m <- Annex.getState Annex.limit
	case m of
		Right r -> return r
		Left l -> do
			let matcher = Utility.Matcher.generate (reverse l)
			Annex.changeState $ \s -> s { Annex.limit = Right matcher }
			return matcher

{- Adds something to the limit list, which is built up reversed. -}
add :: Utility.Matcher.Token (FilePath -> Annex Bool) -> Annex ()
add l = Annex.changeState $ \s -> s { Annex.limit = prepend $ Annex.limit s }
	where
		prepend (Left ls) = Left $ l:ls
		prepend _ = error "internal"

{- Adds a new token. -}
addToken :: String -> Annex ()
addToken = add . Utility.Matcher.token

{- Adds a new limit. -}
addLimit :: Either String MatchFiles -> Annex ()
addLimit = either error (\l -> add $ Utility.Matcher.Operation $ l S.empty)

{- Add a limit to skip files that do not match the glob. -}
addInclude :: String -> Annex ()
addInclude = addLimit . limitInclude

limitInclude :: MkLimit
limitInclude glob = Right $ const $ return . matchglob glob

{- Add a limit to skip files that match the glob. -}
addExclude :: String -> Annex ()
addExclude = addLimit . limitExclude

limitExclude :: MkLimit
limitExclude glob = Right $ const $ return . not . matchglob glob

matchglob :: String -> FilePath -> Bool
matchglob glob f = isJust $ match cregex f []
	where
		cregex = compile regex []
		regex = '^':wildToRegex glob

{- Adds a limit to skip files not believed to be present
 - in a specfied repository. -}
addIn :: String -> Annex ()
addIn = addLimit . limitIn

limitIn :: MkLimit
limitIn name = Right $ \notpresent -> check $
	if name == "."
		then inhere notpresent
		else inremote notpresent
	where
		check a = Backend.lookupFile >=> handle a
		handle _ Nothing = return False
		handle a (Just (key, _)) = a key
		inremote notpresent key = do
			u <- Remote.nameToUUID name
			us <- Remote.keyLocations key
			return $ u `elem` us && u `S.notMember` notpresent
		inhere notpresent key
			| S.null notpresent = inAnnex key
			| otherwise = do
				u <- getUUID
				if u `S.member` notpresent
					then return False
					else inAnnex key

{- Adds a limit to skip files not believed to have the specified number
 - of copies. -}
addCopies :: String -> Annex ()
addCopies = addLimit . limitCopies

limitCopies :: MkLimit
limitCopies want = case split ":" want of
	[v, n] -> case readTrustLevel v of
		Just trust -> go n $ checktrust trust
		Nothing -> go n $ checkgroup v
	[n] -> go n $ const $ return True
	_ -> Left "bad value for copies"
	where
		go num good = case readish num of
			Nothing -> Left "bad number for copies"
			Just n -> Right $ \notpresent ->
				Backend.lookupFile >=> handle n good notpresent
		handle _ _ _ Nothing = return False
		handle n good notpresent (Just (key, _)) = do
			us <- filter (`S.notMember` notpresent)
				<$> (filterM good =<< Remote.keyLocations key)
			return $ length us >= n
		checktrust t u = (== t) <$> lookupTrust u
		checkgroup g u = S.member g <$> lookupGroups u

{- Adds a limit to skip files not using a specified key-value backend. -}
addInBackend :: String -> Annex ()
addInBackend = addLimit . limitInBackend

limitInBackend :: MkLimit
limitInBackend name = Right $ const $ Backend.lookupFile >=> check
	where
		wanted = Backend.lookupBackendName name
		check = return . maybe False ((==) wanted . snd)

{- Adds a limit to skip files that are too large or too small -}
addLargerThan :: String -> Annex ()
addLargerThan = addLimit . limitSize (>)

addSmallerThan :: String -> Annex ()
addSmallerThan = addLimit . limitSize (<)

limitSize :: (Maybe Integer -> Maybe Integer -> Bool) -> MkLimit
limitSize vs s = case readSize dataUnits s of
	Nothing -> Left "bad size"
	Just sz -> Right $ const $ Backend.lookupFile >=> check sz
	where
		check _ Nothing = return False
		check sz (Just (key, _)) = return $ keySize key `vs` Just sz

addTimeLimit :: String -> Annex ()
addTimeLimit s = do
	let seconds = fromMaybe (error "bad time-limit") $ parseDuration s
	start <- liftIO getPOSIXTime
	let cutoff = start + seconds
	addLimit $ Right $ const $ const $ do
		now <- liftIO getPOSIXTime
		if now > cutoff
			then do
				warning $ "Time limit (" ++ s ++ ") reached!"
				liftIO $ exitWith $ ExitFailure 101
			else return True