git-annex/BackendFile.hs
2010-10-13 16:21:50 -04:00

77 lines
2.3 KiB
Haskell

{- git-annex "file" backend
- -}
module BackendFile (backend) where
import System.IO
import System.Cmd
import Control.Exception
import Types
import LocationLog
import Locations
import Remotes
import GitRepo
backend = Backend {
name = "file",
getKey = keyValue,
storeFileKey = dummyStore,
retrieveKeyFile = copyKeyFile,
removeKey = dummyRemove
}
-- direct mapping from filename to key
keyValue :: State -> FilePath -> IO (Maybe Key)
keyValue state file = return $ Just $ Key file
{- 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. So storing or removing a key is
- a no-op. TODO until support is added for git annex --push otherrepo,
- then these could implement that.. -}
dummyStore :: State -> FilePath -> Key -> IO (Bool)
dummyStore state file key = return True
dummyRemove :: State -> Key -> IO Bool
dummyRemove state url = return False
{- Try to find a copy of the file in one of the remotes,
- and copy it over to this one. -}
copyKeyFile :: State -> Key -> FilePath -> IO (Bool)
copyKeyFile state key file = do
remotes <- remotesWithKey state key
if (0 == length remotes)
then error $ "no known remotes have: " ++ (keyFile key) ++ "\n" ++
"(Perhaps you need to git remote add a repository?)"
else trycopy remotes remotes
where
trycopy full [] = error $ "unable to get: " ++ (keyFile key) ++ "\n" ++
"To get that file, need access to one of these remotes: " ++
(remotesList full)
trycopy full (r:rs) = do
putStrLn "trying a remote"
result <- try (copyFromRemote r key file)::IO (Either SomeException ())
case (result) of
Left err -> do
showerr err r
trycopy full rs
Right succ -> return True
showerr err r = do
hPutStrLn stderr $ "git-annex: copy from " ++
(gitRepoDescribe r ) ++ " failed: " ++
(show err)
{- Tries to copy a file from a remote, exception on error. -}
copyFromRemote :: GitRepo -> Key -> FilePath -> IO ()
copyFromRemote r key file = do
r <- if (gitRepoIsLocal r)
then getlocal
else getremote
return ()
where
getlocal = do
putStrLn $ "get: " ++ location
rawSystem "cp" ["-a", location, file]
getremote = do
putStrLn $ "get: " ++ location
error "get via network not yet implemented!"
location = annexLocation r backend key