record transfers for git-annex-shell

Not yet tested and places git-annex-shell is run need to be modified to
pass the new field settings.

Note that rsyncServerSend was changed to fork, rather than directly exec
rsync, because it needs to keep the transfer lock held, and clean up the
transfer log when done.

GitAnnexShell.hs

@@ -9,6 +9,7 @@ module GitAnnexShell where
 
 import System.Environment
 import System.Console.GetOpt
+import Data.Char
 
 import Common.Annex
 import qualified Git.Construct
@@ -84,8 +85,9 @@ builtins = map cmdname cmds
 builtin :: String -> String -> [String] -> IO ()
 builtin cmd dir params = do
 	checkNotReadOnly cmd
-	let (params', fields) = partitionParams params
-	dispatch False (cmd : params') cmds options (parseFields fields) header $
+	let (params', fieldparams) = partitionParams params
+	fields <- filterM checkField $ parseFields fieldparams
+	dispatch False (cmd : params') cmds options fields header $
 		Git.Construct.repoAbsPath dir >>= Git.Construct.fromAbsPath
 
 external :: [String] -> IO ()
@@ -110,6 +112,18 @@ partitionParams params
 parseFields :: [String] -> [(String, String)]
 parseFields = map (separate (== '='))
 
+{- Only allow known fields to be set, ignore others.
+ - Make sure that field values make sense. -}
+checkField :: (String, String) -> IO Bool
+checkField (field, value)
+	| field == "remoteuuid" = return $
+		-- does it look like a UUID?
+		all (\c -> isAlphaNum c || c == '-') value
+	| field == "associatedfile" =
+		-- is the file located within the current directory?
+		dirContains <$> getCurrentDirectory <*> pure value
+	| otherwise = return False
+
 failure :: IO ()
 failure = error $ "bad parameters\n\n" ++ usage header cmds options