d9b4bf4224
I anticipate lots of external special remote programs will neglect implementing this. Still, it's the right thing to do to assume that some of them may write files out of order. Probably most external special remotes will not be used with a proxy. When someone is using one with a proxy, they can always get it fixed to send ORDERED.
609 lines
22 KiB
Haskell
609 lines
22 KiB
Haskell
{- A "remote" that is just a filesystem directory.
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-
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- Copyright 2011-2022 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU AGPL version 3 or higher.
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-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE RankNTypes #-}
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{-# LANGUAGE CPP #-}
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module Remote.Directory (
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remote,
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finalizeStoreGeneric,
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removeDirGeneric,
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) where
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import qualified Data.ByteString.Lazy as L
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import qualified Data.Map as M
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import qualified Data.List.NonEmpty as NE
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import qualified System.FilePath.ByteString as P
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import Data.Default
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import System.PosixCompat.Files (isRegularFile, deviceID)
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#ifndef mingw32_HOST_OS
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import System.PosixCompat.Files (getFdStatus)
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#endif
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import Annex.Common
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import Types.Remote
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import Types.Export
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import Types.Creds
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import qualified Git
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import Config.Cost
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import Config
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import Annex.SpecialRemote.Config
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import Remote.Helper.Special
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import Remote.Helper.ExportImport
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import Remote.Helper.Path
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import Types.Import
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import qualified Remote.Directory.LegacyChunked as Legacy
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import Annex.CopyFile
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import Annex.Content
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import Annex.Perms
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import Annex.UUID
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import Annex.Verify
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import Backend
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import Types.KeySource
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import Types.ProposedAccepted
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import Utility.Metered
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import Utility.Tmp
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import Utility.InodeCache
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import Utility.FileMode
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import Utility.Directory.Create
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import qualified Utility.RawFilePath as R
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#ifndef mingw32_HOST_OS
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import Utility.OpenFd
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#endif
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remote :: RemoteType
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remote = specialRemoteType $ RemoteType
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{ typename = "directory"
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, enumerate = const (findSpecialRemotes "directory")
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, generate = gen
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, configParser = mkRemoteConfigParser
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[ optionalStringParser directoryField
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(FieldDesc "(required) where the special remote stores data")
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, yesNoParser ignoreinodesField (Just False)
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(FieldDesc "ignore inodes when importing/exporting")
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]
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, setup = directorySetup
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, exportSupported = exportIsSupported
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, importSupported = importIsSupported
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, thirdPartyPopulated = False
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}
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directoryField :: RemoteConfigField
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directoryField = Accepted "directory"
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ignoreinodesField :: RemoteConfigField
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ignoreinodesField = Accepted "ignoreinodes"
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gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> RemoteStateHandle -> Annex (Maybe Remote)
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gen r u rc gc rs = do
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c <- parsedRemoteConfig remote rc
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cst <- remoteCost gc c cheapRemoteCost
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let chunkconfig = getChunkConfig c
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cow <- liftIO newCopyCoWTried
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let ii = IgnoreInodes $ fromMaybe True $
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getRemoteConfigValue ignoreinodesField c
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return $ Just $ specialRemote c
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(storeKeyM dir chunkconfig cow)
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(retrieveKeyFileM dir chunkconfig cow)
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(removeKeyM dir)
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(checkPresentM dir chunkconfig)
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Remote
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{ uuid = u
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, cost = cst
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, name = Git.repoDescribe r
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, storeKey = storeKeyDummy
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, retrieveKeyFile = retrieveKeyFileDummy
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, retrieveKeyFileInOrder = pure True
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, retrieveKeyFileCheap = retrieveKeyFileCheapM dir chunkconfig
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, retrievalSecurityPolicy = RetrievalAllKeysSecure
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, removeKey = removeKeyDummy
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, lockContent = Nothing
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, checkPresent = checkPresentDummy
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, checkPresentCheap = True
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, exportActions = ExportActions
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{ storeExport = storeExportM dir cow
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, retrieveExport = retrieveExportM dir cow
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, removeExport = removeExportM dir
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, checkPresentExport = checkPresentExportM dir
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-- Not needed because removeExportLocation
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-- auto-removes empty directories.
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, removeExportDirectory = Nothing
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, renameExport = Just $ renameExportM dir
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}
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, importActions = ImportActions
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{ listImportableContents = listImportableContentsM ii dir
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, importKey = Just (importKeyM ii dir)
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, retrieveExportWithContentIdentifier = retrieveExportWithContentIdentifierM ii dir cow
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, storeExportWithContentIdentifier = storeExportWithContentIdentifierM ii dir cow
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, removeExportWithContentIdentifier = removeExportWithContentIdentifierM ii dir
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-- Not needed because removeExportWithContentIdentifier
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-- auto-removes empty directories.
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, removeExportDirectoryWhenEmpty = Nothing
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, checkPresentExportWithContentIdentifier = checkPresentExportWithContentIdentifierM ii dir
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}
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, whereisKey = Nothing
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, remoteFsck = Nothing
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, repairRepo = Nothing
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, config = c
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, getRepo = return r
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, gitconfig = gc
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, localpath = Just dir'
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, readonly = False
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, appendonly = False
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, untrustworthy = False
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, availability = checkPathAvailability True dir'
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, remotetype = remote
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, mkUnavailable = gen r u rc
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(gc { remoteAnnexDirectory = Just "/dev/null" }) rs
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, getInfo = return [("directory", dir')]
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, claimUrl = Nothing
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, checkUrl = Nothing
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, remoteStateHandle = rs
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}
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where
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dir = toRawFilePath dir'
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dir' = fromMaybe (giveup "missing directory") (remoteAnnexDirectory gc)
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directorySetup :: SetupStage -> Maybe UUID -> Maybe CredPair -> RemoteConfig -> RemoteGitConfig -> Annex (RemoteConfig, UUID)
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directorySetup _ mu _ c gc = do
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u <- maybe (liftIO genUUID) return mu
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-- verify configuration is sane
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let dir = maybe (giveup "Specify directory=") fromProposedAccepted $
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M.lookup directoryField c
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absdir <- liftIO $ fromRawFilePath <$> absPath (toRawFilePath dir)
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liftIO $ unlessM (doesDirectoryExist absdir) $
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giveup $ "Directory does not exist: " ++ absdir
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(c', _encsetup) <- encryptionSetup c gc
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-- The directory is stored in git config, not in this remote's
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-- persistent state, so it can vary between hosts.
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gitConfigSpecialRemote u c' [("directory", absdir)]
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return (M.delete directoryField c', u)
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{- Locations to try to access a given Key in the directory.
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- We try more than one since we used to write to different hash
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- directories. -}
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locations :: RawFilePath -> Key -> NE.NonEmpty RawFilePath
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locations d k = NE.map (d P.</>) (keyPaths k)
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locations' :: RawFilePath -> Key -> [RawFilePath]
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locations' d k = NE.toList (locations d k)
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{- Returns the location of a Key in the directory. If the key is
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- present, returns the location that is actually used, otherwise
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- returns the first, default location. -}
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getLocation :: RawFilePath -> Key -> IO RawFilePath
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getLocation d k = do
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let locs = locations d k
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fromMaybe (NE.head locs)
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<$> firstM (doesFileExist . fromRawFilePath)
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(NE.toList locs)
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{- Directory where the file(s) for a key are stored. -}
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storeDir :: RawFilePath -> Key -> RawFilePath
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storeDir d k = P.addTrailingPathSeparator $
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d P.</> hashDirLower def k P.</> keyFile k
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{- Check if there is enough free disk space in the remote's directory to
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- store the key. Note that the unencrypted key size is checked. -}
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storeKeyM :: RawFilePath -> ChunkConfig -> CopyCoWTried -> Storer
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storeKeyM d chunkconfig cow k c m =
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ifM (checkDiskSpaceDirectory d k)
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( do
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void $ liftIO $ tryIO $ createDirectoryUnder [d] tmpdir
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store
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, giveup "Not enough free disk space."
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)
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where
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store = case chunkconfig of
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LegacyChunks chunksize ->
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let go _k b p = liftIO $ Legacy.store
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(fromRawFilePath d)
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chunksize
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(finalizeStoreGeneric d)
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k b p
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(fromRawFilePath tmpdir)
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(fromRawFilePath destdir)
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in byteStorer go k c m
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NoChunks ->
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let go _k src p = liftIO $ do
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void $ fileCopier cow src tmpf p Nothing
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finalizeStoreGeneric d tmpdir destdir
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in fileStorer go k c m
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_ ->
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let go _k b p = liftIO $ do
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meteredWriteFile p tmpf b
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finalizeStoreGeneric d tmpdir destdir
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in byteStorer go k c m
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tmpdir = P.addTrailingPathSeparator $ d P.</> "tmp" P.</> kf
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tmpf = fromRawFilePath tmpdir </> fromRawFilePath kf
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kf = keyFile k
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destdir = storeDir d k
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checkDiskSpaceDirectory :: RawFilePath -> Key -> Annex Bool
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checkDiskSpaceDirectory d k = do
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annexdir <- fromRepo gitAnnexObjectDir
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samefilesystem <- liftIO $ catchDefaultIO False $
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(\a b -> deviceID a == deviceID b)
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<$> R.getSymbolicLinkStatus d
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<*> R.getSymbolicLinkStatus annexdir
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checkDiskSpace Nothing (Just d) k 0 samefilesystem
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{- Passed a temp directory that contains the files that should be placed
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- in the dest directory, moves it into place. Anything already existing
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- in the dest directory will be deleted. File permissions will be locked
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- down. -}
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finalizeStoreGeneric :: RawFilePath -> RawFilePath -> RawFilePath -> IO ()
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finalizeStoreGeneric d tmp dest = do
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removeDirGeneric False (fromRawFilePath d) dest'
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createDirectoryUnder [d] (parentDir dest)
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renameDirectory (fromRawFilePath tmp) dest'
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-- may fail on some filesystems
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void $ tryIO $ do
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mapM_ (preventWrite . toRawFilePath) =<< dirContents dest'
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preventWrite dest
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where
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dest' = fromRawFilePath dest
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retrieveKeyFileM :: RawFilePath -> ChunkConfig -> CopyCoWTried -> Retriever
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retrieveKeyFileM d (LegacyChunks _) _ = Legacy.retrieve locations' d
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retrieveKeyFileM d NoChunks cow = fileRetriever' $ \dest k p iv -> do
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src <- liftIO $ fromRawFilePath <$> getLocation d k
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void $ liftIO $ fileCopier cow src (fromRawFilePath dest) p iv
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retrieveKeyFileM d _ _ = byteRetriever $ \k sink ->
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sink =<< liftIO (L.readFile . fromRawFilePath =<< getLocation d k)
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retrieveKeyFileCheapM :: RawFilePath -> ChunkConfig -> Maybe (Key -> AssociatedFile -> FilePath -> Annex ())
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-- no cheap retrieval possible for chunks
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retrieveKeyFileCheapM _ (UnpaddedChunks _) = Nothing
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retrieveKeyFileCheapM _ (LegacyChunks _) = Nothing
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#ifndef mingw32_HOST_OS
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retrieveKeyFileCheapM d NoChunks = Just $ \k _af f -> liftIO $ do
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file <- fromRawFilePath <$> (absPath =<< getLocation d k)
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ifM (doesFileExist file)
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( R.createSymbolicLink (toRawFilePath file) (toRawFilePath f)
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, giveup "content file not present in remote"
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)
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#else
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retrieveKeyFileCheapM _ _ = Nothing
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#endif
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removeKeyM :: RawFilePath -> Remover
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removeKeyM d _proof k = liftIO $ removeDirGeneric True
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(fromRawFilePath d)
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(fromRawFilePath (storeDir d k))
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{- Removes the directory, which must be located under the topdir.
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-
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- Succeeds even on directories and contents that do not have write
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- permission, if it's possible to turn the write bit on.
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-
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- If the directory does not exist, succeeds as long as the topdir does
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- exist. If the topdir does not exist, fails, because in this case the
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- remote is not currently accessible and probably still has the content
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- we were supposed to remove from it.
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-
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- Empty parent directories (up to but not including the topdir)
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- can also be removed. Failure to remove such a directory is not treated
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- as an error.
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-}
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removeDirGeneric :: Bool -> FilePath -> FilePath -> IO ()
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removeDirGeneric removeemptyparents topdir dir = do
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void $ tryIO $ allowWrite (toRawFilePath dir)
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#ifdef mingw32_HOST_OS
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{- Windows needs the files inside the directory to be writable
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- before it can delete them. -}
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void $ tryIO $ mapM_ (allowWrite . toRawFilePath) =<< dirContents dir
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#endif
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tryNonAsync (removeDirectoryRecursive dir) >>= \case
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Right () -> return ()
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Left e ->
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unlessM (doesDirectoryExist topdir <&&> (not <$> doesDirectoryExist dir)) $
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throwM e
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when removeemptyparents $ do
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subdir <- relPathDirToFile (toRawFilePath topdir) (P.takeDirectory (toRawFilePath dir))
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goparents (Just (P.takeDirectory subdir)) (Right ())
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where
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goparents _ (Left _e) = return ()
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goparents Nothing _ = return ()
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goparents (Just subdir) _ = do
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let d = topdir </> fromRawFilePath subdir
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goparents (upFrom subdir) =<< tryIO (removeDirectory d)
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checkPresentM :: RawFilePath -> ChunkConfig -> CheckPresent
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checkPresentM d (LegacyChunks _) k = Legacy.checkKey d locations' k
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checkPresentM d _ k = checkPresentGeneric d (locations' d k)
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checkPresentGeneric :: RawFilePath -> [RawFilePath] -> Annex Bool
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checkPresentGeneric d ps = checkPresentGeneric' d $
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liftIO $ anyM (doesFileExist . fromRawFilePath) ps
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checkPresentGeneric' :: RawFilePath -> Annex Bool -> Annex Bool
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checkPresentGeneric' d check = ifM check
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( return True
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, ifM (liftIO $ doesDirectoryExist (fromRawFilePath d))
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( return False
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, giveup $ "directory " ++ fromRawFilePath d ++ " is not accessible"
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)
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)
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storeExportM :: RawFilePath -> CopyCoWTried -> FilePath -> Key -> ExportLocation -> MeterUpdate -> Annex ()
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storeExportM d cow src _k loc p = do
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liftIO $ createDirectoryUnder [d] (P.takeDirectory dest)
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-- Write via temp file so that checkPresentGeneric will not
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-- see it until it's fully stored.
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viaTmp go (fromRawFilePath dest) ()
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where
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dest = exportPath d loc
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go tmp () = void $ liftIO $ fileCopier cow src tmp p Nothing
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retrieveExportM :: RawFilePath -> CopyCoWTried -> Key -> ExportLocation -> FilePath -> MeterUpdate -> Annex Verification
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retrieveExportM d cow k loc dest p =
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verifyKeyContentIncrementally AlwaysVerify k $ \iv ->
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void $ liftIO $ fileCopier cow src dest p iv
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where
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src = fromRawFilePath $ exportPath d loc
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removeExportM :: RawFilePath -> Key -> ExportLocation -> Annex ()
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removeExportM d _k loc = liftIO $ do
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removeWhenExistsWith R.removeLink src
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removeExportLocation d loc
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where
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src = exportPath d loc
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checkPresentExportM :: RawFilePath -> Key -> ExportLocation -> Annex Bool
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checkPresentExportM d _k loc =
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checkPresentGeneric d [exportPath d loc]
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renameExportM :: RawFilePath -> Key -> ExportLocation -> ExportLocation -> Annex (Maybe ())
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renameExportM d _k oldloc newloc = liftIO $ do
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createDirectoryUnder [d] (P.takeDirectory dest)
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renameFile (fromRawFilePath src) (fromRawFilePath dest)
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removeExportLocation d oldloc
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return (Just ())
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where
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src = exportPath d oldloc
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dest = exportPath d newloc
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exportPath :: RawFilePath -> ExportLocation -> RawFilePath
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exportPath d loc = d P.</> fromExportLocation loc
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{- Removes the ExportLocation's parent directory and its parents, so long as
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- they're empty, up to but not including the topdir. -}
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removeExportLocation :: RawFilePath -> ExportLocation -> IO ()
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removeExportLocation topdir loc =
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go (Just $ P.takeDirectory $ fromExportLocation loc) (Right ())
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where
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go _ (Left _e) = return ()
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go Nothing _ = return ()
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go (Just loc') _ =
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let p = fromRawFilePath $ exportPath topdir $
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mkExportLocation loc'
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in go (upFrom loc') =<< tryIO (removeDirectory p)
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listImportableContentsM :: IgnoreInodes -> RawFilePath -> Annex (Maybe (ImportableContentsChunkable Annex (ContentIdentifier, ByteSize)))
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listImportableContentsM ii dir = liftIO $ do
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l <- dirContentsRecursiveSkipping (const False) False (fromRawFilePath dir)
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l' <- mapM (go . toRawFilePath) l
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return $ Just $ ImportableContentsComplete $
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ImportableContents (catMaybes l') []
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where
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go f = do
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st <- R.getSymbolicLinkStatus f
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mkContentIdentifier ii f st >>= \case
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Nothing -> return Nothing
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Just cid -> do
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relf <- relPathDirToFile dir f
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sz <- getFileSize' f st
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return $ Just (mkImportLocation relf, (cid, sz))
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newtype IgnoreInodes = IgnoreInodes Bool
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-- Make a ContentIdentifier that contains the size and mtime of the file,
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-- and also normally the inode, unless ignoreinodes=yes.
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--
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-- If the file is not a regular file, this will return Nothing.
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mkContentIdentifier :: IgnoreInodes -> RawFilePath -> FileStatus -> IO (Maybe ContentIdentifier)
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mkContentIdentifier (IgnoreInodes ii) f st =
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liftIO $ fmap (ContentIdentifier . encodeBS . showInodeCache)
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<$> if ii
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then toInodeCache' noTSDelta f st 0
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else toInodeCache noTSDelta f st
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-- Since ignoreinodes can be changed by enableremote, and since previous
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-- versions of git-annex ignored inodes by default, treat two content
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-- identifiers as the same if they differ only by one having the inode
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-- ignored.
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guardSameContentIdentifiers :: a -> [ContentIdentifier] -> Maybe ContentIdentifier -> a
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guardSameContentIdentifiers _ _ Nothing = giveup "file not found"
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guardSameContentIdentifiers cont olds (Just new)
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| any (new ==) olds = cont
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| any (ignoreinode new ==) olds = cont
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| any (\old -> new == ignoreinode old) olds = cont
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| otherwise = giveup "file content has changed"
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where
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ignoreinode cid@(ContentIdentifier b) =
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case readInodeCache (decodeBS b) of
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Nothing -> cid
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Just ic ->
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let ic' = replaceInode 0 ic
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in ContentIdentifier (encodeBS (showInodeCache ic'))
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importKeyM :: IgnoreInodes -> RawFilePath -> ExportLocation -> ContentIdentifier -> ByteSize -> MeterUpdate -> Annex (Maybe Key)
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importKeyM ii dir loc cid sz p = do
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backend <- chooseBackend f
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unsizedk <- fst <$> genKey ks p backend
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let k = alterKey unsizedk $ \kd -> kd
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{ keySize = keySize kd <|> Just sz }
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currcid <- liftIO $ mkContentIdentifier ii absf
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=<< R.getSymbolicLinkStatus absf
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guardSameContentIdentifiers (return (Just k)) [cid] currcid
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where
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f = fromExportLocation loc
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absf = dir P.</> f
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ks = KeySource
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{ keyFilename = f
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, contentLocation = absf
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, inodeCache = Nothing
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}
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retrieveExportWithContentIdentifierM :: IgnoreInodes -> RawFilePath -> CopyCoWTried -> ExportLocation -> [ContentIdentifier] -> FilePath -> Either Key (Annex Key) -> MeterUpdate -> Annex (Key, Verification)
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retrieveExportWithContentIdentifierM ii dir cow loc cids dest gk p =
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case gk of
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Right mkkey -> do
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go Nothing
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k <- mkkey
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return (k, UnVerified)
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Left k -> do
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v <- verifyKeyContentIncrementally DefaultVerify k go
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return (k, v)
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where
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f = exportPath dir loc
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f' = fromRawFilePath f
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go iv = precheck (docopy iv)
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docopy iv = ifM (liftIO $ tryCopyCoW cow f' dest p)
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( postcheckcow (liftIO $ maybe noop unableIncrementalVerifier iv)
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, docopynoncow iv
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)
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docopynoncow iv = do
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#ifndef mingw32_HOST_OS
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|
let open = do
|
|
-- Need a duplicate fd for the post check.
|
|
fd <- openFdWithMode f ReadOnly Nothing defaultFileFlags
|
|
dupfd <- dup fd
|
|
h <- fdToHandle fd
|
|
return (h, dupfd)
|
|
let close (h, dupfd) = do
|
|
hClose h
|
|
closeFd dupfd
|
|
bracketIO open close $ \(h, dupfd) -> do
|
|
#else
|
|
let open = openBinaryFile f' ReadMode
|
|
let close = hClose
|
|
bracketIO open close $ \h -> do
|
|
#endif
|
|
liftIO $ fileContentCopier h dest p iv
|
|
#ifndef mingw32_HOST_OS
|
|
postchecknoncow dupfd (return ())
|
|
#else
|
|
postchecknoncow (return ())
|
|
#endif
|
|
|
|
-- Check before copy, to avoid expensive copy of wrong file
|
|
-- content.
|
|
precheck cont = guardSameContentIdentifiers cont cids
|
|
=<< liftIO . mkContentIdentifier ii f
|
|
=<< liftIO (R.getSymbolicLinkStatus f)
|
|
|
|
-- Check after copy, in case the file was changed while it was
|
|
-- being copied.
|
|
--
|
|
-- When possible (not on Windows), check the same handle
|
|
-- that the file was copied from. Avoids some race cases where
|
|
-- the file is modified while it's copied but then gets restored
|
|
-- to the original content afterwards.
|
|
--
|
|
-- This does not guard against every possible race, but neither
|
|
-- can InodeCaches detect every possible modification to a file.
|
|
-- It's probably as good or better than git's handling of similar
|
|
-- situations with files being modified while it's updating the
|
|
-- working tree for a merge.
|
|
#ifndef mingw32_HOST_OS
|
|
postchecknoncow fd cont = do
|
|
#else
|
|
postchecknoncow cont = do
|
|
#endif
|
|
currcid <- liftIO $ mkContentIdentifier ii f
|
|
#ifndef mingw32_HOST_OS
|
|
=<< getFdStatus fd
|
|
#else
|
|
=<< R.getSymbolicLinkStatus f
|
|
#endif
|
|
guardSameContentIdentifiers cont cids currcid
|
|
|
|
-- When copy-on-write was done, cannot check the handle that was
|
|
-- copied from, but such a copy should run very fast, so
|
|
-- it's very unlikely that the file changed after precheck,
|
|
-- the modified version was copied CoW, and then the file was
|
|
-- restored to the original content before this check.
|
|
postcheckcow cont = do
|
|
currcid <- liftIO $ mkContentIdentifier ii f
|
|
=<< R.getSymbolicLinkStatus f
|
|
guardSameContentIdentifiers cont cids currcid
|
|
|
|
storeExportWithContentIdentifierM :: IgnoreInodes -> RawFilePath -> CopyCoWTried -> FilePath -> Key -> ExportLocation -> [ContentIdentifier] -> MeterUpdate -> Annex ContentIdentifier
|
|
storeExportWithContentIdentifierM ii dir cow src _k loc overwritablecids p = do
|
|
liftIO $ createDirectoryUnder [dir] (toRawFilePath destdir)
|
|
withTmpFileIn destdir template $ \tmpf tmph -> do
|
|
liftIO $ hClose tmph
|
|
void $ liftIO $ fileCopier cow src tmpf p Nothing
|
|
let tmpf' = toRawFilePath tmpf
|
|
resetAnnexFilePerm tmpf'
|
|
liftIO (R.getSymbolicLinkStatus tmpf') >>= liftIO . mkContentIdentifier ii tmpf' >>= \case
|
|
Nothing -> giveup "unable to generate content identifier"
|
|
Just newcid -> do
|
|
checkExportContent ii dir loc
|
|
overwritablecids
|
|
(giveup "unsafe to overwrite file")
|
|
(const $ liftIO $ R.rename tmpf' dest)
|
|
return newcid
|
|
where
|
|
dest = exportPath dir loc
|
|
(destdir, base) = splitFileName (fromRawFilePath dest)
|
|
template = relatedTemplate (base ++ ".tmp")
|
|
|
|
removeExportWithContentIdentifierM :: IgnoreInodes -> RawFilePath -> Key -> ExportLocation -> [ContentIdentifier] -> Annex ()
|
|
removeExportWithContentIdentifierM ii dir k loc removeablecids =
|
|
checkExportContent ii dir loc removeablecids (giveup "unsafe to remove modified file") $ \case
|
|
DoesNotExist -> return ()
|
|
KnownContentIdentifier -> removeExportM dir k loc
|
|
|
|
checkPresentExportWithContentIdentifierM :: IgnoreInodes -> RawFilePath -> Key -> ExportLocation -> [ContentIdentifier] -> Annex Bool
|
|
checkPresentExportWithContentIdentifierM ii dir _k loc knowncids =
|
|
checkPresentGeneric' dir $
|
|
checkExportContent ii dir loc knowncids (return False) $ \case
|
|
DoesNotExist -> return False
|
|
KnownContentIdentifier -> return True
|
|
|
|
data CheckResult = DoesNotExist | KnownContentIdentifier
|
|
|
|
-- Checks if the content at an ExportLocation is in the knowncids,
|
|
-- and only runs the callback that modifies it if it's safe to do so.
|
|
--
|
|
-- This should avoid races to the extent possible. However,
|
|
-- if something has the file open for write, it could write to the handle
|
|
-- after the callback has overwritten or deleted it, and its write would
|
|
-- be lost, and we don't need to detect that.
|
|
-- (In similar situations, git doesn't either!)
|
|
--
|
|
-- It follows that if something is written to the destination file
|
|
-- shortly before, it's acceptable to run the callback anyway, as that's
|
|
-- nearly indistinguishable from the above case.
|
|
--
|
|
-- So, it suffices to check if the destination file's current
|
|
-- content is known, and immediately run the callback.
|
|
checkExportContent :: IgnoreInodes -> RawFilePath -> ExportLocation -> [ContentIdentifier] -> Annex a -> (CheckResult -> Annex a) -> Annex a
|
|
checkExportContent ii dir loc knowncids unsafe callback =
|
|
tryWhenExists (liftIO $ R.getSymbolicLinkStatus dest) >>= \case
|
|
Just destst
|
|
| not (isRegularFile destst) -> unsafe
|
|
| otherwise -> catchDefaultIO Nothing (liftIO $ mkContentIdentifier ii dest destst) >>= \case
|
|
Just destcid
|
|
| destcid `elem` knowncids -> callback KnownContentIdentifier
|
|
-- dest exists with other content
|
|
| otherwise -> unsafe
|
|
-- should never happen
|
|
Nothing -> unsafe
|
|
-- dest does not exist
|
|
Nothing -> callback DoesNotExist
|
|
where
|
|
dest = exportPath dir loc
|