implement GETCONFIG and SETCONFIG

Changed protocol spec to make SETCONFIG only store it persistently when run
during INITREMOTE. I see no reason to support storing it persistently at
other times, and doing so would unnecessarily complicate the code.

Also, letting that be done would probably result in use for storing data that
doesn't really belong there, and special remote authors who don't
understand how the union merging works would probably be surprised the
results.

Remote/External.hs

@@ -39,7 +39,7 @@ remote = RemoteType {
 
 gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
 gen r u c gc = do
-	external <- newExternal externaltype
+	external <- newExternal externaltype c
 	Annex.addCleanup (fromUUID u) $ stopExternal external
 	cst <- getCost external r gc
 	return $ Just $ encryptableRemote c
@@ -76,14 +76,15 @@ externalSetup mu c = do
 		M.lookup "externaltype" c
 	c' <- encryptionSetup c
 
-	external <- newExternal externaltype
+	external <- newExternal externaltype c'
 	handleRequest external INITREMOTE Nothing $ \resp -> case resp of
 		INITREMOTE_SUCCESS -> Just noop
 		INITREMOTE_FAILURE errmsg -> Just $ error errmsg
 		_ -> Nothing
+	c'' <- liftIO $ atomically $ readTMVar $ externalConfig external
 
-	gitConfigSpecialRemote u c' "externaltype" externaltype
+	gitConfigSpecialRemote u c'' "externaltype" externaltype
-	return (c', u)
+	return (c'', u)
 
 store :: External -> Key -> AssociatedFile -> MeterUpdate -> Annex Bool
 store external k _f p = sendAnnex k rollback $ \f ->
@@ -201,8 +202,15 @@ handleRequest' lck external req mp responsehandler = do
 		maybe noop (\a -> liftIO $ a bytesprocessed) mp
 	handleRemoteRequest (DIRHASH k) = 
 		sendMessage lck external (VALUE $ hashDirMixed k)
-	handleRemoteRequest (SETCONFIG setting value) = error "TODO"
+	handleRemoteRequest (SETCONFIG setting value) =
-	handleRemoteRequest (GETCONFIG setting) = error "TODO"
+		liftIO $ atomically $ do
+			let v = externalConfig external
+			m <- takeTMVar v
+			putTMVar v $ M.insert setting value m
+	handleRemoteRequest (GETCONFIG setting) = do
+		value <- fromMaybe "" . M.lookup setting
+			<$> liftIO (atomically $ readTMVar $ externalConfig external)
+		sendMessage lck external (VALUE value)
 	handleRemoteRequest (SETSTATE k value) = error "TODO"
 	handleRemoteRequest (GETSTATE k) = error "TODO"
 	handleRemoteRequest (VERSION _) =

Remote/External/Types.hs

@@ -30,11 +30,12 @@ module Remote.External.Types (
 ) where
 
 import Common.Annex
-import Types.Key
-import Utility.Metered
-import Logs.Transfer
-import Config.Cost
 import Annex.Exception
+import Types.Key (file2key, key2file)
+import Utility.Metered (BytesProcessed(..))
+import Logs.Transfer (Direction(..))
+import Config.Cost (Cost)
+import Types.Remote (RemoteConfig)
 
 import Data.Char
 import Control.Concurrent.STM
@@ -47,13 +48,16 @@ data External = External
 	, externalState :: TMVar ExternalState
 	-- Empty when a remote is in use.
 	, externalLock :: TMVar ExternalLock
+	-- Never left empty.
+	, externalConfig :: TMVar RemoteConfig
 	}
 
-newExternal :: ExternalType -> Annex External
+newExternal :: ExternalType -> RemoteConfig -> Annex External
-newExternal externaltype = liftIO $ External
+newExternal externaltype c = liftIO $ External
 	<$> pure externaltype
 	<*> atomically newEmptyTMVar
 	<*> atomically (newTMVar ExternalLock)
+	<*> atomically (newTMVar c)
 
 type ExternalType = String
 

doc/design/external_special_remote_protocol.mdwn

@@ -177,14 +177,17 @@ in control.
   creating hash directory structures to store Keys in.  
   (git-annex replies with VALUE followed by the value.)
 * `SETCONFIG Setting`  
-  Sets one of the special remote's configuration settings. These settings
+  Sets one of the special remote's configuration settings.  
-  are stored in the git-annex branch, so will be available if the same
+  Normally this is sent during INITREMOTE, which allows these settings
-  special remote is used elsewhere.  
+  to be stored in the git-annex branch, so will be available if the same
-  (Typically only done during INITREMOTE, although it is accepted at other
+  special remote is used elsewhere. (If sent after INITREMOTE, the changed
-  times.)
+  configuration will only be available while the remote is running.)
 * `GETCONFIG Setting`  
-  Gets one of the special remote's configuration settings.  
+  Gets one of the special remote's configuration settings, which can have
-  (git-annex replies with VALUE followed by the value.)
+  been passed by the user when running `git annex initremote`, or
+  can have been set by a previous SETCONFIG. Can be run at any time.  
+  (git-annex replies with VALUE followed by the value. If the setting is
+  not set, the value will be empty.)
 * `SETSTATE Key Value`  
   git-annex can store state in the git-annex branch on a
   per-special-remote, per-key basis. This sets that state.