95 lines
3 KiB
Haskell
95 lines
3 KiB
Haskell
{- git-annex command
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-
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- Copyright 2011 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Command.Migrate where
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import Common.Annex
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import Command
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import Backend
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import qualified Types.Key
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import Types.Backend (canUpgradeKey, fastMigrate)
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import Types.KeySource
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import Annex.Content
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import qualified Command.ReKey
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import qualified Command.Fsck
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import qualified Annex
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import Logs.MetaData
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cmd :: Command
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cmd = notDirect $ withGlobalOptions annexedMatchingOptions $
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command "migrate" SectionUtility
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"switch data to different backend"
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paramPaths (withParams seek)
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seek :: CmdParams -> CommandSeek
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seek = withFilesInGit $ whenAnnexed start
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start :: FilePath -> Key -> CommandStart
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start file key = do
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forced <- Annex.getState Annex.force
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v <- Backend.getBackend file key
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case v of
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Nothing -> stop
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Just oldbackend -> do
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exists <- inAnnex key
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newbackend <- choosebackend =<< chooseBackend file
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if (newbackend /= oldbackend || upgradableKey oldbackend key || forced) && exists
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then do
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showStart "migrate" file
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next $ perform file key oldbackend newbackend
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else stop
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where
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choosebackend Nothing = Prelude.head <$> orderedList
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choosebackend (Just backend) = return backend
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{- Checks if a key is upgradable to a newer representation.
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-
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- Reasons for migration:
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- - Ideally, all keys have file size metadata. Old keys may not.
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- - Something has changed in the backend, such as a bug fix.
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-}
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upgradableKey :: Backend -> Key -> Bool
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upgradableKey backend key = isNothing (Types.Key.keySize key) || backendupgradable
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where
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backendupgradable = maybe False (\a -> a key) (canUpgradeKey backend)
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{- Store the old backend's key in the new backend
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- The old backend's key is not dropped from it, because there may
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- be other files still pointing at that key.
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-
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- To ensure that the data we have for the old key is valid, it's
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- fscked here. First we generate the new key. This ensures that the
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- data cannot get corrupted after the fsck but before the new key is
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- generated.
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-}
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perform :: FilePath -> Key -> Backend -> Backend -> CommandPerform
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perform file oldkey oldbackend newbackend = go =<< genkey
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where
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go Nothing = stop
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go (Just (newkey, knowngoodcontent))
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| knowngoodcontent = finish newkey
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| otherwise = stopUnless checkcontent $ finish newkey
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checkcontent = Command.Fsck.checkBackend oldbackend oldkey Command.Fsck.KeyLocked $ Just file
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finish newkey = ifM (Command.ReKey.linkKey file oldkey newkey)
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( do
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copyMetaData oldkey newkey
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next $ Command.ReKey.cleanup file oldkey newkey
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, error "failed"
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)
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genkey = case maybe Nothing (\fm -> fm oldkey newbackend (Just file)) (fastMigrate oldbackend) of
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Just newkey -> return $ Just (newkey, True)
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Nothing -> do
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content <- calcRepo $ gitAnnexLocation oldkey
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let source = KeySource
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{ keyFilename = file
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, contentLocation = content
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, inodeCache = Nothing
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}
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v <- genKey source (Just newbackend)
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return $ case v of
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Just (newkey, _) -> Just (newkey, False)
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_ -> Nothing
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