5004381dd9
Prompted by the test suite on windows failing to with "export foo failed" and no information about what went wrong. Note that only storeExportWithContentIdentifier has been converted. storeExport still returns a Bool and so exceptions may be hidden. However, storeExportWithContentIdentifier has many more failure modes, since it needs to avoid overwriting modified files. So it's more important it have better error display.
340 lines
12 KiB
Haskell
340 lines
12 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 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 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 qualified Data.Map as M
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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 (RemoteConfig -> 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 = \_ _ _ _ -> do
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warning "store export is unsupported"
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return False
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, retrieveExport = \_ _ _ _ -> return False
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, checkPresentExport = \_ _ -> return False
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, removeExport = \_ _ -> return False
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, removeExportDirectory = Just $ \_ -> return False
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, renameExport = \_ _ _ -> return Nothing
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}
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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 (RemoteConfig -> 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 = \_ _ _ _ _ -> return Nothing
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, storeExportWithContentIdentifier = \_ _ _ _ _ -> return (Left "import not supported")
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, removeExportWithContentIdentifier = \_ _ _ -> return False
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, removeExportDirectoryWhenEmpty = Just $ \_ -> return False
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, checkPresentExportWithContentIdentifier = \_ _ _ -> return False
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}
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exportIsSupported :: RemoteConfig -> RemoteGitConfig -> Annex Bool
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exportIsSupported = \_ _ -> return True
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importIsSupported :: RemoteConfig -> 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 =
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let checkconfig supported configured setting cont =
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ifM (supported rt c gc)
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( case st of
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Init
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| configured c && isEncrypted c ->
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giveup $ "cannot enable both encryption and " ++ setting
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| otherwise -> cont
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Enable oldc
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| configured c /= configured oldc ->
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giveup $ "cannot change " ++ setting ++ " of existing special remote"
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| otherwise -> cont
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, if configured c
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then giveup $ setting ++ " is not supported by this special remote"
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else cont
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)
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in checkconfig exportSupported exportTree "exporttree" $
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checkconfig importSupported importTree "importtree" $
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if importTree c && not (exportTree c)
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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 -> Annex Remote
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adjustExportImport r = case M.lookup "exporttree" (config r) of
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Nothing -> return $ notexport r
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Just c -> case yesNo c of
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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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Nothing -> do
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warning $ "bad exporttree value for " ++ name r ++ ", assuming not an export"
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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 (uuid r') 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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updateexportdb exportdb 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 (uuid r')) oldks
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storeExportWithContentIdentifier (importActions r') f k loc oldcids p >>= \case
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Left err -> do
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warning err
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return False
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Right newcid -> do
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withExclusiveLock gitAnnexContentIdentifierLock $ do
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liftIO $ ContentIdentifier.recordContentIdentifier db (uuid r') newcid k
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liftIO $ ContentIdentifier.flushDbQueue db
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recordContentIdentifier (uuid r') newcid k
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return True
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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 = \_ _ _ -> do
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warning "remote is configured with exporttree=yes; use `git-annex export` to store content on it"
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return False
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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 do
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ret@(ok, _v) <- retrieveKeyFile r k af dest p
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if ok
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then return ret
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else 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 \_ _ _ -> return False
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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 -> do
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warning "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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return False
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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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exportupdated <- liftIO $ newTMVarIO ()
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return (dbv, lcklckv, exportinconflict, exportupdated)
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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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getexportdb (dbv, lcklckv, _, _) =
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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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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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-- Check once if the export log is different than the database and
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-- updates the database, to notice when an export has been
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-- updated from another repository.
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updateexportdb db (_, _, exportinconflict, exportupdated) =
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liftIO (atomically (tryTakeTMVar exportupdated)) >>= \case
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Just () -> 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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Nothing -> return ()
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getexportlocs dbv k = do
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db <- getexportdb dbv
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updateexportdb db dbv
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liftIO $ Export.getExportTree db k
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retrieveKeyFileFromExport dbv k _af dest p = unVerified $
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if maybe False (isJust . verifyKeyContent) (maybeLookupBackendVariety (keyVariety k))
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then do
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locs <- getexportlocs dbv k
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case locs of
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[] -> do
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ifM (liftIO $ atomically $ readTVar $ getexportinconflict dbv)
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( warning "unknown export location, likely due to the export conflict"
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, warning "unknown export location"
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)
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return False
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(l:_) -> retrieveExport (exportActions r) k l dest p
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else do
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warning $ "exported content cannot be verified due to using the " ++ decodeBS (formatKeyVariety (keyVariety k)) ++ " backend"
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return False
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