037440ef36
Part of ongoing transition to make remote methods throw exceptions, rather than silently hide them. This commit was sponsored by Ilya Shlyakhter on Patreon.
324 lines
11 KiB
Haskell
324 lines
11 KiB
Haskell
{- Helper to make remotes support export and import (or not).
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-
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- Copyright 2017-2019 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 FlexibleInstances, FlexibleContexts #-}
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module Remote.Helper.ExportImport where
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import Annex.Common
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import Types.Remote
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import Types.Backend
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import Types.Key
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import Types.ProposedAccepted
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import Backend
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import Remote.Helper.Encryptable (isEncrypted)
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import qualified Database.Export as Export
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import qualified Database.ContentIdentifier as ContentIdentifier
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import Annex.Export
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import Annex.LockFile
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import Annex.SpecialRemote.Config
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import Git.Types (fromRef)
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import Logs.Export
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import Logs.ContentIdentifier (recordContentIdentifier)
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import Control.Concurrent.STM
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-- | Use for remotes that do not support exports.
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class HasExportUnsupported a where
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exportUnsupported :: a
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instance HasExportUnsupported (ParsedRemoteConfig -> RemoteGitConfig -> Annex Bool) where
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exportUnsupported = \_ _ -> return False
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instance HasExportUnsupported (ExportActions Annex) where
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exportUnsupported = ExportActions
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{ storeExport = nope
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, retrieveExport = nope
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, checkPresentExport = \_ _ -> return False
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, removeExport = nope
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, removeExportDirectory = nope
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, renameExport = \_ _ _ -> return Nothing
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}
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where
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nope = giveup "export not supported"
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-- | Use for remotes that do not support imports.
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class HasImportUnsupported a where
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importUnsupported :: a
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instance HasImportUnsupported (ParsedRemoteConfig -> RemoteGitConfig -> Annex Bool) where
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importUnsupported = \_ _ -> return False
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instance HasImportUnsupported (ImportActions Annex) where
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importUnsupported = ImportActions
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{ listImportableContents = return Nothing
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, retrieveExportWithContentIdentifier = nope
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, storeExportWithContentIdentifier = nope
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, removeExportWithContentIdentifier = nope
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, removeExportDirectoryWhenEmpty = nope
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, checkPresentExportWithContentIdentifier = \_ _ _ -> return False
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}
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where
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nope = giveup "import not supported"
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exportIsSupported :: ParsedRemoteConfig -> RemoteGitConfig -> Annex Bool
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exportIsSupported = \_ _ -> return True
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importIsSupported :: ParsedRemoteConfig -> RemoteGitConfig -> Annex Bool
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importIsSupported = \_ _ -> return True
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-- | Prevent or allow exporttree=yes and importtree=yes when
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-- setting up a new remote, depending on exportSupported and importSupported.
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adjustExportImportRemoteType :: RemoteType -> RemoteType
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adjustExportImportRemoteType rt = rt { setup = setup' }
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where
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setup' st mu cp c gc = do
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pc <- either giveup return . parseRemoteConfig c
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=<< configParser rt c
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let checkconfig supported configured configfield cont =
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ifM (supported rt pc gc)
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( case st of
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Init
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| configured pc && isEncrypted pc ->
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giveup $ "cannot enable both encryption and " ++ fromProposedAccepted configfield
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| otherwise -> cont
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Enable oldc -> do
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oldpc <- parsedRemoteConfig rt oldc
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if configured pc /= configured oldpc
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then giveup $ "cannot change " ++ fromProposedAccepted configfield ++ " of existing special remote"
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else cont
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, if configured pc
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then giveup $ fromProposedAccepted configfield ++ " is not supported by this special remote"
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else cont
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)
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checkconfig exportSupported exportTree exportTreeField $
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checkconfig importSupported importTree importTreeField $
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if importTree pc && not (exportTree pc)
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then giveup "cannot enable importtree=yes without also enabling exporttree=yes"
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else setup rt st mu cp c gc
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-- | Adjust a remote to support exporttree=yes and importree=yes.
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--
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-- Note that all remotes with importree=yes also have exporttree=yes.
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adjustExportImport :: Remote -> RemoteStateHandle -> Annex Remote
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adjustExportImport r rs = case getRemoteConfigValue exportTreeField (config r) of
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Nothing -> return $ notexport r
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Just True -> ifM (isExportSupported r)
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( do
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exportdbv <- prepexportdb
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r' <- isexport exportdbv
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if importTree (config r)
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then isimport r' exportdbv
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else return r'
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, return $ notexport r
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)
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Just False -> return $ notexport r
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where
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notexport r' = notimport r'
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{ exportActions = exportUnsupported
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, remotetype = (remotetype r')
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{ exportSupported = exportUnsupported
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}
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}
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notimport r' = r'
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{ importActions = importUnsupported
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, remotetype = (remotetype r')
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{ importSupported = importUnsupported
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}
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}
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isimport r' exportdbv = do
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ciddbv <- prepciddb
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let keycids k = do
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db <- getciddb ciddbv
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liftIO $ ContentIdentifier.getContentIdentifiers db rs k
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let checkpresent k loc =
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checkPresentExportWithContentIdentifier
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(importActions r')
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k loc
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=<< keycids k
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return $ r'
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{ exportActions = (exportActions r')
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{ storeExport = \f k loc p -> do
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db <- getciddb ciddbv
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exportdb <- getexportdb exportdbv
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oldks <- liftIO $ Export.getExportTreeKey exportdb loc
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oldcids <- liftIO $ concat
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<$> mapM (ContentIdentifier.getContentIdentifiers db rs) oldks
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newcid <- storeExportWithContentIdentifier (importActions r') f k loc oldcids p
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withExclusiveLock gitAnnexContentIdentifierLock $ do
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liftIO $ ContentIdentifier.recordContentIdentifier db rs newcid k
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liftIO $ ContentIdentifier.flushDbQueue db
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recordContentIdentifier rs newcid k
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, removeExport = \k loc ->
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removeExportWithContentIdentifier (importActions r') k loc
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=<< keycids k
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, removeExportDirectory = removeExportDirectoryWhenEmpty (importActions r')
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-- renameExport is optional, and the
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-- remote's implementation may
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-- lose modifications to the file
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-- (by eg copying and then deleting)
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-- so don't use it
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, renameExport = \_ _ _ -> return Nothing
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, checkPresentExport = checkpresent
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}
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, checkPresent = if appendonly r'
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then checkPresent r'
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else \k -> anyM (checkpresent k)
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=<< getexportlocs exportdbv k
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, getInfo = do
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is <- getInfo r'
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return (is++[("import", "yes")])
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}
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isexport dbv = return $ r
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-- Storing a key on an export could be implemented,
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-- but it would perform unncessary work
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-- when another repository has already stored the
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-- key, and the local repository does not know
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-- about it. To avoid unnecessary costs, don't do it.
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{ storeKey = \_ _ _ ->
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giveup "remote is configured with exporttree=yes; use `git-annex export` to store content on it"
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-- Keys can be retrieved using retrieveExport,
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-- but since that retrieves from a path in the
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-- remote that another writer could have replaced
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-- with content not of the requested key,
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-- the content has to be strongly verified.
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--
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-- appendonly remotes have a key/value store,
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-- so don't need to use retrieveExport. However,
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-- fall back to it if retrieveKeyFile fails.
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, retrieveKeyFile = \k af dest p ->
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let retrieveexport = retrieveKeyFileFromExport dbv k af dest p
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in if appendonly r
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then retrieveKeyFile r k af dest p
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`catchNonAsync` const retrieveexport
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else retrieveexport
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, retrieveKeyFileCheap = if appendonly r
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then retrieveKeyFileCheap r
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else Nothing
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-- Removing a key from an export would need to
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-- change the tree in the export log to not include
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-- the file. Otherwise, conflicts when removing
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-- files would not be dealt with correctly.
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-- There does not seem to be a good use case for
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-- removing a key from an export in any case.
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, removeKey = \_k -> giveup "dropping content from an export is not supported; use `git annex export` to export a tree that lacks the files you want to remove"
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-- Can't lock content on exports, since they're
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-- not key/value stores, and someone else could
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-- change what's exported to a file at any time.
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--
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-- (except for appendonly remotes)
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, lockContent = if appendonly r
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then lockContent r
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else Nothing
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-- Check if any of the files a key was exported to
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-- are present. This doesn't guarantee the export
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-- contains the right content, which is why export
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-- remotes are untrusted.
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--
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-- (but appendonly remotes work the same as any
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-- non-export remote)
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, checkPresent = if appendonly r
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then checkPresent r
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else \k -> anyM (checkPresentExport (exportActions r) k)
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=<< getexportlocs dbv k
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-- checkPresent from an export is more expensive
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-- than otherwise, so not cheap. Also, this
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-- avoids things that look at checkPresentCheap and
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-- silently skip non-present files from behaving
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-- in confusing ways when there's an export
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-- conflict.
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, checkPresentCheap = False
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, mkUnavailable = return Nothing
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, getInfo = do
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ts <- map fromRef . exportedTreeishes
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<$> getExport (uuid r)
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is <- getInfo r
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return (is++[("export", "yes"), ("exportedtree", unwords ts)])
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}
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prepciddb = do
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lcklckv <- liftIO newEmptyTMVarIO
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dbtv <- liftIO newEmptyTMVarIO
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return (dbtv, lcklckv)
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prepexportdb = do
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lcklckv <- liftIO newEmptyTMVarIO
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dbv <- liftIO newEmptyTMVarIO
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exportinconflict <- liftIO $ newTVarIO False
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return (dbv, lcklckv, exportinconflict)
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-- Only open the database once it's needed.
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getciddb (dbtv, lcklckv) =
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liftIO (atomically (tryReadTMVar dbtv)) >>= \case
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Just db -> return db
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-- let only one thread take the lock
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Nothing -> ifM (liftIO $ atomically $ tryPutTMVar lcklckv ())
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( do
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db <- ContentIdentifier.openDb
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ContentIdentifier.needsUpdateFromLog db >>= \case
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Just v -> withExclusiveLock gitAnnexContentIdentifierLock $
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ContentIdentifier.updateFromLog db v
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Nothing -> noop
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liftIO $ atomically $ putTMVar dbtv db
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return db
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-- loser waits for winner to open the db and
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-- can then also use its handle
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, liftIO $ atomically (readTMVar dbtv)
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)
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-- Only open the database once it's needed.
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--
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-- After opening the database, check if the export log is
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-- different than the database, and update the database, to notice
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-- when an export has been updated from another repository.
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getexportdb (dbv, lcklckv, exportinconflict) =
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liftIO (atomically (tryReadTMVar dbv)) >>= \case
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Just db -> return db
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-- let only one thread take the lock
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Nothing -> ifM (liftIO $ atomically $ tryPutTMVar lcklckv ())
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( do
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db <- Export.openDb (uuid r)
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updateexportdb db exportinconflict
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liftIO $ atomically $ putTMVar dbv db
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return db
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-- loser waits for winner to open the db and
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-- can then also use its handle
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, liftIO $ atomically (readTMVar dbv)
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)
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getexportinconflict (_, _, v) = v
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updateexportdb db exportinconflict =
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Export.updateExportTreeFromLog db >>= \case
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Export.ExportUpdateSuccess -> return ()
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Export.ExportUpdateConflict -> do
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warnExportImportConflict r
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liftIO $ atomically $
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writeTVar exportinconflict True
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getexportlocs dbv k = do
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db <- getexportdb dbv
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liftIO $ Export.getExportTree db k
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retrieveKeyFileFromExport dbv k _af dest p
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| maybe False (isJust . verifyKeyContent) (maybeLookupBackendVariety (fromKey keyVariety k)) = do
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locs <- getexportlocs dbv k
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case locs of
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[] -> ifM (liftIO $ atomically $ readTVar $ getexportinconflict dbv)
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( giveup "unknown export location, likely due to the export conflict"
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, giveup "unknown export location"
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)
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(l:_) -> do
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retrieveExport (exportActions r) k l dest p
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return UnVerified
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| otherwise = giveup $ "exported content cannot be verified due to using the " ++ decodeBS (formatKeyVariety (fromKey keyVariety k)) ++ " backend"
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