git-annex/Remote/Hook.hs
Joey Hess b4cf22a388 pushed checkPresent exception handling out of Remote implementations
I tend to prefer moving toward explicit exception handling, not away from
it, but in this case, I think there are good reasons to let checkPresent
throw exceptions:

1. They can all be caught in one place (Remote.hasKey), and we know
   every possible exception is caught there now, which we didn't before.
2. It simplified the code of the Remotes. I think it makes sense for
   Remotes to be able to be implemented without needing to worry about
   catching exceptions inside them. (Mostly.)
3. Types.StoreRetrieve.Preparer can only work on things that return a
   Bool, which all the other relevant remote methods already did.
   I do not see a good way to generalize that type; my previous attempts
   failed miserably.
2014-08-06 13:45:19 -04:00

142 lines
4 KiB
Haskell

{- A remote that provides hooks to run shell commands.
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Remote.Hook (remote) where
import qualified Data.Map as M
import Common.Annex
import Types.Remote
import Types.Key
import Types.Creds
import qualified Git
import Config
import Config.Cost
import Annex.UUID
import Remote.Helper.Special
import Utility.Env
type Action = String
type HookName = String
remote :: RemoteType
remote = RemoteType {
typename = "hook",
enumerate = findSpecialRemotes "hooktype",
generate = gen,
setup = hookSetup
}
gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
gen r u c gc = do
cst <- remoteCost gc expensiveRemoteCost
return $ Just $ specialRemote c
(simplyPrepare $ store hooktype)
(simplyPrepare $ retrieve hooktype)
Remote {
uuid = u,
cost = cst,
name = Git.repoDescribe r,
storeKey = storeKeyDummy,
retrieveKeyFile = retreiveKeyFileDummy,
retrieveKeyFileCheap = retrieveCheap hooktype,
removeKey = remove hooktype,
checkPresent = checkKey r hooktype,
checkPresentCheap = False,
whereisKey = Nothing,
remoteFsck = Nothing,
repairRepo = Nothing,
config = c,
localpath = Nothing,
repo = r,
gitconfig = gc,
readonly = False,
availability = GloballyAvailable,
remotetype = remote
}
where
hooktype = fromMaybe (error "missing hooktype") $ remoteAnnexHookType gc
hookSetup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
hookSetup mu _ c = do
u <- maybe (liftIO genUUID) return mu
let hooktype = fromMaybe (error "Specify hooktype=") $
M.lookup "hooktype" c
c' <- encryptionSetup c
gitConfigSpecialRemote u c' "hooktype" hooktype
return (c', u)
hookEnv :: Action -> Key -> Maybe FilePath -> IO (Maybe [(String, String)])
hookEnv action k f = Just <$> mergeenv (fileenv f ++ keyenv)
where
mergeenv l = addEntries l <$> getEnvironment
envvar s v = ("ANNEX_" ++ s, v)
keyenv = catMaybes
[ Just $ envvar "KEY" (key2file k)
, Just $ envvar "ACTION" action
, envvar "HASH_1" <$> headMaybe hashbits
, envvar "HASH_2" <$> headMaybe (drop 1 hashbits)
]
fileenv Nothing = []
fileenv (Just file) = [envvar "FILE" file]
hashbits = map takeDirectory $ splitPath $ hashDirMixed k
lookupHook :: HookName -> Action -> Annex (Maybe String)
lookupHook hookname action = do
command <- getConfig (annexConfig hook) ""
if null command
then do
fallback <- getConfig (annexConfig hookfallback) ""
if null fallback
then do
warning $ "missing configuration for " ++ hook ++ " or " ++ hookfallback
return Nothing
else return $ Just fallback
else return $ Just command
where
hook = hookname ++ "-" ++ action ++ "-hook"
hookfallback = hookname ++ "-hook"
runHook :: HookName -> Action -> Key -> Maybe FilePath -> Annex Bool -> Annex Bool
runHook hook action k f a = maybe (return False) run =<< lookupHook hook action
where
run command = do
showOutput -- make way for hook output
ifM (liftIO $ boolSystemEnv "sh" [Param "-c", Param command] =<< hookEnv action k f)
( a
, do
warning $ hook ++ " hook exited nonzero!"
return False
)
store :: HookName -> Storer
store h = fileStorer $ \k src _p ->
runHook h "store" k (Just src) $ return True
retrieve :: HookName -> Retriever
retrieve h = fileRetriever $ \d k _p ->
unlessM (runHook h "retrieve" k (Just d) $ return True) $
error "failed to retrieve content"
retrieveCheap :: HookName -> Key -> FilePath -> Annex Bool
retrieveCheap _ _ _ = return False
remove :: HookName -> Key -> Annex Bool
remove h k = runHook h "remove" k Nothing $ return True
checkKey :: Git.Repo -> HookName -> Key -> Annex Bool
checkKey r h k = do
showAction $ "checking " ++ Git.repoDescribe r
v <- lookupHook h action
liftIO $ check v
where
action = "checkpresent"
findkey s = key2file k `elem` lines s
check Nothing = error $ action ++ " hook misconfigured"
check (Just hook) = do
environ <- hookEnv action k Nothing
findkey <$> readProcessEnv "sh" ["-c", hook] environ