e38a839a80
Moving the portability handling into a small C library cleans up things a lot, avoiding the pain of unpacking structs from inside haskell code.
329 lines
10 KiB
Haskell
329 lines
10 KiB
Haskell
{- git-annex file content managing
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-
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- Copyright 2010 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Annex.Content (
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inAnnex,
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inAnnexSafe,
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lockContent,
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calcGitLink,
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logStatus,
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getViaTmp,
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getViaTmpUnchecked,
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withTmp,
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checkDiskSpace,
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moveAnnex,
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removeAnnex,
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fromAnnex,
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moveBad,
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getKeysPresent,
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saveState,
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downloadUrl,
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preseedTmp,
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) where
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import Control.Exception (bracket_)
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import System.Posix.Types
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import System.IO.Unsafe (unsafeInterleaveIO)
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import Common.Annex
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import Logs.Location
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import Annex.UUID
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import qualified Git
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import qualified Annex
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import qualified Annex.Queue
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import qualified Annex.Branch
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import Utility.DiskFree
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import Utility.FileMode
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import qualified Utility.Url as Url
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import Types.Key
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import Utility.DataUnits
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import Utility.CopyFile
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import Config
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import Annex.Exception
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{- Checks if a given key's content is currently present. -}
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inAnnex :: Key -> Annex Bool
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inAnnex = inAnnex' doesFileExist
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inAnnex' :: (FilePath -> IO a) -> Key -> Annex a
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inAnnex' a key = do
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whenM (fromRepo Git.repoIsUrl) $
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error "inAnnex cannot check remote repo"
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inRepo $ \g -> gitAnnexLocation key g >>= a
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{- A safer check; the key's content must not only be present, but
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- is not in the process of being removed. -}
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inAnnexSafe :: Key -> Annex (Maybe Bool)
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inAnnexSafe = inAnnex' $ \f -> openForLock f False >>= check
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where
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check Nothing = return is_missing
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check (Just h) = do
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v <- getLock h (ReadLock, AbsoluteSeek, 0, 0)
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closeFd h
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return $ case v of
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Just _ -> is_locked
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Nothing -> is_unlocked
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is_locked = Nothing
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is_unlocked = Just True
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is_missing = Just False
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{- Content is exclusively locked while running an action that might remove
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- it. (If the content is not present, no locking is done.) -}
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lockContent :: Key -> Annex a -> Annex a
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lockContent key a = do
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file <- inRepo $ gitAnnexLocation key
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bracketIO (openForLock file True >>= lock) unlock a
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where
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lock Nothing = return Nothing
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lock (Just l) = do
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v <- tryIO $ setLock l (WriteLock, AbsoluteSeek, 0, 0)
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case v of
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Left _ -> error "content is locked"
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Right _ -> return $ Just l
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unlock Nothing = return ()
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unlock (Just l) = closeFd l
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openForLock :: FilePath -> Bool -> IO (Maybe Fd)
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openForLock file writelock = bracket_ prep cleanup go
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where
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go = catchMaybeIO $ openFd file mode Nothing defaultFileFlags
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mode = if writelock then ReadWrite else ReadOnly
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{- Since files are stored with the write bit disabled,
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- have to fiddle with permissions to open for an
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- exclusive lock. -}
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forwritelock a =
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when writelock $ whenM (doesFileExist file) a
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prep = forwritelock $ allowWrite file
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cleanup = forwritelock $ preventWrite file
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{- Calculates the relative path to use to link a file to a key. -}
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calcGitLink :: FilePath -> Key -> Annex FilePath
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calcGitLink file key = do
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cwd <- liftIO getCurrentDirectory
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let absfile = fromMaybe whoops $ absNormPath cwd file
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loc <- inRepo $ gitAnnexLocation key
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return $ relPathDirToFile (parentDir absfile) loc
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where
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whoops = error $ "unable to normalize " ++ file
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{- Updates the Logs.Location when a key's presence changes in the current
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- repository. -}
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logStatus :: Key -> LogStatus -> Annex ()
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logStatus key status = do
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u <- getUUID
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logChange key u status
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{- Runs an action, passing it a temporary filename to get,
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- and if the action succeeds, moves the temp file into
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- the annex as a key's content. -}
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getViaTmp :: Key -> (FilePath -> Annex Bool) -> Annex Bool
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getViaTmp key action = do
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tmp <- fromRepo $ gitAnnexTmpLocation key
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-- Check that there is enough free disk space.
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-- When the temp file already exists, count the space
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-- it is using as free.
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e <- liftIO $ doesFileExist tmp
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if e
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then do
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stat <- liftIO $ getFileStatus tmp
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checkDiskSpace' (fromIntegral $ fileSize stat) key
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else checkDiskSpace key
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when e $ liftIO $ allowWrite tmp
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getViaTmpUnchecked key action
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prepTmp :: Key -> Annex FilePath
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prepTmp key = do
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tmp <- fromRepo $ gitAnnexTmpLocation key
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liftIO $ createDirectoryIfMissing True (parentDir tmp)
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return tmp
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{- Like getViaTmp, but does not check that there is enough disk space
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- for the incoming key. For use when the key content is already on disk
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- and not being copied into place. -}
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getViaTmpUnchecked :: Key -> (FilePath -> Annex Bool) -> Annex Bool
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getViaTmpUnchecked key action = do
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tmp <- prepTmp key
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ifM (action tmp)
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( do
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moveAnnex key tmp
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logStatus key InfoPresent
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return True
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, do
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-- the tmp file is left behind, in case caller wants
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-- to resume its transfer
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return False
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)
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{- Creates a temp file, runs an action on it, and cleans up the temp file. -}
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withTmp :: Key -> (FilePath -> Annex a) -> Annex a
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withTmp key action = do
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tmp <- prepTmp key
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res <- action tmp
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liftIO $ whenM (doesFileExist tmp) $ liftIO $ removeFile tmp
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return res
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{- Checks that there is disk space available to store a given key,
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- throwing an error if not. -}
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checkDiskSpace :: Key -> Annex ()
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checkDiskSpace = checkDiskSpace' 0
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checkDiskSpace' :: Integer -> Key -> Annex ()
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checkDiskSpace' adjustment key = do
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reserve <- getDiskReserve
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free <- inRepo $ getDiskFree . gitAnnexDir
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case (free, keySize key) of
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(Just have, Just need) ->
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when (need + reserve > have + adjustment) $
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needmorespace (need + reserve - have - adjustment)
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_ -> return ()
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where
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needmorespace n = unlessM (Annex.getState Annex.force) $
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error $ "not enough free space, need " ++
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roughSize storageUnits True n ++
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" more" ++ forcemsg
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forcemsg = " (use --force to override this check or adjust annex.diskreserve)"
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{- Moves a file into .git/annex/objects/
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-
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- What if the key there already has content? This could happen for
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- various reasons; perhaps the same content is being annexed again.
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- Perhaps there has been a hash collision generating the keys.
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-
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- The current strategy is to assume that in this case it's safe to delete
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- one of the two copies of the content; and the one already in the annex
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- is left there, assuming it's the original, canonical copy.
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-
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- I considered being more paranoid, and checking that both files had
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- the same content. Decided against it because A) users explicitly choose
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- a backend based on its hashing properties and so if they're dealing
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- with colliding files it's their own fault and B) adding such a check
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- would not catch all cases of colliding keys. For example, perhaps
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- a remote has a key; if it's then added again with different content then
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- the overall system now has two different peices of content for that
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- key, and one of them will probably get deleted later. So, adding the
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- check here would only raise expectations that git-annex cannot truely
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- meet.
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-}
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moveAnnex :: Key -> FilePath -> Annex ()
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moveAnnex key src = do
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dest <- inRepo $ gitAnnexLocation key
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let dir = parentDir dest
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liftIO $ ifM (doesFileExist dest)
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( removeFile src
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, do
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createDirectoryIfMissing True dir
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allowWrite dir -- in case the directory already exists
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moveFile src dest
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preventWrite dest
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preventWrite dir
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)
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withObjectLoc :: Key -> ((FilePath, FilePath) -> Annex a) -> Annex a
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withObjectLoc key a = do
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file <- inRepo $ gitAnnexLocation key
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let dir = parentDir file
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a (dir, file)
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cleanObjectLoc :: Key -> Annex ()
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cleanObjectLoc key = do
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file <- inRepo $ gitAnnexLocation key
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liftIO $ removeparents file (3 :: Int)
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where
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removeparents _ 0 = return ()
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removeparents file n = do
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let dir = parentDir file
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maybe (return ()) (const $ removeparents dir (n-1))
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=<< catchMaybeIO (removeDirectory dir)
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{- Removes a key's file from .git/annex/objects/ -}
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removeAnnex :: Key -> Annex ()
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removeAnnex key = withObjectLoc key $ \(dir, file) -> do
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liftIO $ do
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allowWrite dir
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removeFile file
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cleanObjectLoc key
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{- Moves a key's file out of .git/annex/objects/ -}
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fromAnnex :: Key -> FilePath -> Annex ()
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fromAnnex key dest = withObjectLoc key $ \(dir, file) -> do
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liftIO $ do
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allowWrite dir
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allowWrite file
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moveFile file dest
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cleanObjectLoc key
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{- Moves a key out of .git/annex/objects/ into .git/annex/bad, and
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- returns the file it was moved to. -}
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moveBad :: Key -> Annex FilePath
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moveBad key = do
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src <- inRepo $ gitAnnexLocation key
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bad <- fromRepo gitAnnexBadDir
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let dest = bad </> takeFileName src
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liftIO $ do
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createDirectoryIfMissing True (parentDir dest)
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allowWrite (parentDir src)
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moveFile src dest
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cleanObjectLoc key
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logStatus key InfoMissing
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return dest
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{- List of keys whose content exists in .git/annex/objects/ -}
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getKeysPresent :: Annex [Key]
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getKeysPresent = liftIO . traverse (2 :: Int) =<< fromRepo gitAnnexObjectDir
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where
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traverse depth dir = do
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contents <- catchDefaultIO (dirContents dir) []
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if depth == 0
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then continue (mapMaybe (fileKey . takeFileName) contents) []
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else do
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let deeper = traverse (depth - 1)
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continue [] (map deeper contents)
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continue keys [] = return keys
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continue keys (a:as) = do
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{- Force lazy traversal with unsafeInterleaveIO. -}
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morekeys <- unsafeInterleaveIO a
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continue (morekeys++keys) as
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{- Things to do to record changes to content when shutting down.
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-
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- It's acceptable to avoid committing changes to the branch,
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- especially if performing a short-lived action.
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-}
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saveState :: Bool -> Annex ()
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saveState oneshot = do
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Annex.Queue.flush False
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unless oneshot $
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ifM alwayscommit
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( Annex.Branch.commit "update" , Annex.Branch.stage)
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where
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alwayscommit = fromMaybe True . Git.configTrue
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<$> getConfig "annex.alwayscommit" ""
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{- Downloads content from any of a list of urls. -}
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downloadUrl :: [Url.URLString] -> FilePath -> Annex Bool
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downloadUrl urls file = do
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o <- map Param . words <$> getConfig "annex.web-options" ""
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liftIO $ anyM (\u -> Url.download u o file) urls
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{- Copies a key's content, when present, to a temp file.
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- This is used to speed up some rsyncs. -}
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preseedTmp :: Key -> FilePath -> Annex Bool
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preseedTmp key file = go =<< inAnnex key
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where
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go False = return False
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go True = do
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ok <- copy
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when ok $ liftIO $ allowWrite file
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return ok
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copy = ifM (liftIO $ doesFileExist file)
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( return True
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, do
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s <- inRepo $ gitAnnexLocation key
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liftIO $ copyFileExternal s file
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)
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