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|
{- git-annex pseudo-backend
-
- This backend does not really do any independant data storage,
- it relies on the file contents in .git/annex/ in this repo,
- and other accessible repos.
-
- This is an abstract backend; getKey has to be implemented to complete
- it.
-}
module Backend.File (backend) where
import Control.Monad.State
import System.IO
import System.Cmd
import System.Cmd.Utils
import Control.Exception
import List
import Maybe
import TypeInternals
import LocationLog
import Locations
import qualified Remotes
import qualified GitRepo as Git
import Utility
import Core
import qualified Annex
import UUID
import qualified Backend
backend = Backend {
name = mustProvide,
getKey = mustProvide,
storeFileKey = dummyStore,
retrieveKeyFile = copyKeyFile,
removeKey = checkRemoveKey,
hasKey = checkKeyFile
}
mustProvide = error "must provide this field"
{- Storing a key is a no-op. -}
dummyStore :: FilePath -> Key -> Annex (Bool)
dummyStore file key = return True
{- Just check if the .git/annex/ file for the key exists. -}
checkKeyFile :: Key -> Annex Bool
checkKeyFile k = inAnnex k
{- Try to find a copy of the file in one of the remotes,
- and copy it over to this one. -}
copyKeyFile :: Key -> FilePath -> Annex (Bool)
copyKeyFile key file = do
remotes <- Remotes.withKey key
if (0 == length remotes)
then do
showNote $ "No available git remotes have the file."
showLocations key
return False
else trycopy remotes remotes
where
trycopy full [] = do
showNote $
"need access to one of these remotes: " ++
(Remotes.list full)
return False
trycopy full (r:rs) = do
-- annexLocation needs the git config to have been
-- read for a remote, so do that now,
-- if it hasn't been already
result <- Remotes.tryGitConfigRead r
case (result) of
Nothing -> trycopy full rs
Just r' -> do
showNote $ "copying from " ++ (Git.repoDescribe r ) ++ "..."
liftIO $ copyFromRemote r' key file
{- Tries to copy a file from a remote. -}
copyFromRemote :: Git.Repo -> Key -> FilePath -> IO Bool
copyFromRemote r key file = do
if (Git.repoIsLocal r)
then getlocal
else getremote
where
getlocal = boolSystem "cp" ["-a", location, file]
getremote = return False -- TODO implement get from remote
location = annexLocation r key
showLocations :: Key -> Annex ()
showLocations key = do
g <- Annex.gitRepo
u <- getUUID g
uuids <- liftIO $ keyLocations g key
let uuidsf = filter (\v -> v /= u) uuids
ppuuids <- prettyPrintUUIDs uuidsf
if (0 < length uuidsf)
then showLongNote $ "Try making some of these repositories available:\n" ++ ppuuids
else showLongNote $ "No other repository is known to contain the file."
{- Checks remotes to verify that enough copies of a key exist to allow
- for a key to be safely removed (with no data loss), and fails with an
- error if not. -}
checkRemoveKey :: Key -> Annex (Bool)
checkRemoveKey key = do
force <- Annex.flagIsSet Force
if (force)
then return True
else do
g <- Annex.gitRepo
let numcopies = read $ Git.configGet g config "1"
remotes <- Remotes.withKey key
if (numcopies > length remotes)
then retNotEnoughCopiesKnown remotes numcopies
else findcopies numcopies remotes []
where
config = "annex.numcopies"
findcopies 0 _ _ = return True -- success, enough copies found
findcopies _ [] bad = notEnoughCopiesSeen bad
findcopies n (r:rs) bad = do
all <- Annex.supportedBackends
result <- liftIO $ ((try $ remoteHasKey r all)::IO (Either SomeException Bool))
case (result) of
Right True -> findcopies (n-1) rs bad
Right False -> findcopies n rs bad
Left _ -> findcopies n rs (r:bad)
remoteHasKey r all = do
-- To check if a remote has a key, construct a new
-- Annex monad and query its backend.
a <- Annex.new r all
(result, _) <- Annex.run a (Backend.hasKey key)
return result
notEnoughCopiesSeen bad = do
unsafe
if (0 /= length bad) then listbad bad else return ()
showLocations key
hint
return False
listbad bad =
showLongNote $
"I was unable to access these remotes: " ++
(Remotes.list bad)
retNotEnoughCopiesKnown remotes numcopies = do
unsafe
showLongNote $
"Could only verify the existence of " ++
(show $ length remotes) ++
" out of " ++ (show numcopies) ++
" necessary copies"
showLocations key
hint
return False
unsafe = showNote "unsafe"
hint = showLongNote $ "(Use --force to override this check, or adjust annex.numcopies.)"
|
