convert configParser to Annex action and add passthrough option

Needed so Remote.External can query the external program for its
configs. When the external program does not support the query,
the passthrough option will make all input fields be available.

Annex/SpecialRemote/Config.hs

@@ -93,8 +93,8 @@ importTree :: ParsedRemoteConfig -> Bool
 importTree = fromMaybe False . getRemoteConfigValue importTreeField
 
 {- Parsers for fields that are common to all special remotes. -}
-commonFieldsParser :: [RemoteConfigParser]
-commonFieldsParser =
+commonFieldParsers :: [RemoteConfigFieldParser]
+commonFieldParsers =
 	[ optionalStringParser nameField
 	, optionalStringParser sameasNameField
 	, optionalStringParser sameasUUIDField
@@ -166,11 +166,13 @@ getRemoteConfigValue f m = case M.lookup f m of
 			]
 	Nothing -> Nothing
 
-parseRemoteConfig :: RemoteConfig -> [RemoteConfigParser] -> Either String ParsedRemoteConfig
-parseRemoteConfig c ps =
-	go [] (M.filterWithKey notaccepted c) (ps ++ commonFieldsParser)
+parseRemoteConfig :: RemoteConfig -> RemoteConfigParser -> Either String ParsedRemoteConfig
+parseRemoteConfig c rpc =
+	go [] (M.filterWithKey notaccepted c) (remoteConfigFieldParsers rpc ++ commonFieldParsers)
   where
 	go l c' []
+		| remoteConfigRestPassthrough rpc = Right $ M.fromList $
+			l ++ map (uncurry passthrough) (M.toList c')
 		| M.null c' = Right (M.fromList l)
 		| otherwise = Left $ "Unexpected fields: " ++
 			unwords (map fromProposedAccepted (M.keys c'))
@@ -179,19 +181,22 @@ parseRemoteConfig c ps =
 		case v of
 			Just v' -> go ((f,v'):l) (M.delete f c') rest
 			Nothing -> go l (M.delete f c') rest
+	
+	passthrough f v = (f, RemoteConfigValue (fromProposedAccepted v))
+
 	notaccepted (Proposed _) _ = True
 	notaccepted (Accepted _) _ = False
 
-optionalStringParser :: RemoteConfigField -> RemoteConfigParser
+optionalStringParser :: RemoteConfigField -> RemoteConfigFieldParser
 optionalStringParser f = (f, p)
   where
 	p (Just v) _c = Right (Just (RemoteConfigValue (fromProposedAccepted v)))
 	p Nothing _c = Right Nothing
 
-yesNoParser :: RemoteConfigField -> Bool -> RemoteConfigParser
+yesNoParser :: RemoteConfigField -> Bool -> RemoteConfigFieldParser
 yesNoParser = genParser yesNo "yes or no"
 
-trueFalseParser :: RemoteConfigField -> Bool -> RemoteConfigParser
+trueFalseParser :: RemoteConfigField -> Bool -> RemoteConfigFieldParser
 trueFalseParser = genParser Git.Config.isTrueFalse "true or false"
 
 genParser
@@ -200,7 +205,7 @@ genParser
 	-> String -- ^ description of the value
 	-> RemoteConfigField
 	-> t -- ^ fallback value
-	-> RemoteConfigParser
+	-> RemoteConfigFieldParser
 genParser parse desc f fallback = (f, p)
   where
 	p Nothing _c = Right (Just (RemoteConfigValue fallback))