Fix use of several config settings

annex.ssh-options, annex.rsync-options, annex.bup-split-options.

And adjust types to avoid the bugs that broke several config settings
recently. Now "annex." prefixing is enforced at the type level.

Config.hs

@@ -1,6 +1,6 @@
 {- Git configuration
  -
- - Copyright 2011 Joey Hess <joey@kitenet.net>
+ - Copyright 2011-2012 Joey Hess <joey@kitenet.net>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
@@ -14,29 +14,40 @@ import qualified Git.Command
 import qualified Annex
 import Utility.DataUnits
 
-type ConfigKey = String
+type UnqualifiedConfigKey = String
+data ConfigKey = ConfigKey String
 
 {- Changes a git config setting in both internal state and .git/config -}
 setConfig :: ConfigKey -> String -> Annex ()
-setConfig k value = do
-	inRepo $ Git.Command.run "config" [Param k, Param value]
+setConfig (ConfigKey key) value = do
+	inRepo $ Git.Command.run "config" [Param key, Param value]
 	-- re-read git config and update the repo's state
 	newg <- inRepo Git.Config.read
 	Annex.changeState $ \s -> s { Annex.repo = newg }
 
-{- Looks up a git config setting in git config. -}
+{- Unsets a git config setting. (Leaves it in state currently.) -}
+unsetConfig :: ConfigKey -> Annex ()
+unsetConfig (ConfigKey key) = inRepo $ Git.Command.run "config"
+        [Param "--unset", Param key]
+
+{- Looks up a setting in git config. -}
 getConfig :: ConfigKey -> String -> Annex String
-getConfig key def = fromRepo $ Git.Config.get key def
+getConfig (ConfigKey key) def = fromRepo $ Git.Config.get key def
 
 {- Looks up a per-remote config setting in git config.
  - Failing that, tries looking for a global config option. -}
-getRemoteConfig :: Git.Repo -> ConfigKey -> String -> Annex String
-getRemoteConfig r key def =
-	getConfig (remoteConfig r key) =<< getConfig key def
+getRemoteConfig :: Git.Repo -> UnqualifiedConfigKey -> String -> Annex String
+getRemoteConfig r key def = 
+	getConfig (remoteConfig r key) =<< getConfig (annexConfig key) def
 
 {- A per-remote config setting in git config. -}
-remoteConfig :: Git.Repo -> ConfigKey -> String
-remoteConfig r key = "remote." ++ fromMaybe "" (Git.remoteName r) ++ ".annex-" ++ key
+remoteConfig :: Git.Repo -> UnqualifiedConfigKey -> ConfigKey
+remoteConfig r key = ConfigKey $
+	"remote." ++ fromMaybe "" (Git.remoteName r) ++ ".annex-" ++ key
+
+{- A global annex setting in git config. -}
+annexConfig :: UnqualifiedConfigKey -> ConfigKey
+annexConfig key = ConfigKey $ "annex." ++ key
 
 {- Calculates cost for a remote. Either the default, or as configured 
  - by remote.<name>.annex-cost, or if remote.<name>.annex-cost-command
@@ -83,17 +94,19 @@ getNumCopies v = perhaps (use v) =<< Annex.getState Annex.forcenumcopies
 	where
 		use (Just n) = return n
 		use Nothing = perhaps (return 1) =<< 
-			readish <$> getConfig "annex.numcopies" "1"
+			readish <$> getConfig (annexConfig "numcopies") "1"
 		perhaps fallback = maybe fallback (return . id)
 
 {- Gets the trust level set for a remote in git config. -}
 getTrustLevel :: Git.Repo -> Annex (Maybe String)
-getTrustLevel r = fromRepo $ Git.Config.getMaybe $ remoteConfig r "trustlevel"
+getTrustLevel r = fromRepo $ Git.Config.getMaybe key
+	where
+		(ConfigKey key) = remoteConfig r "trustlevel"
 
 {- Gets annex.diskreserve setting. -}
 getDiskReserve :: Annex Integer
 getDiskReserve = fromMaybe megabyte . readSize dataUnits
-	<$> getConfig "annex.diskreserve" ""
+	<$> getConfig (annexConfig "diskreserve") ""
 	where
 		megabyte = 1000000
 
@@ -101,7 +114,7 @@ getDiskReserve = fromMaybe megabyte . readSize dataUnits
  - splitting it into lines. -}
 getHttpHeaders :: Annex [String]
 getHttpHeaders = do
-	cmd <- getConfig "annex.http-headers-command" ""
+	cmd <- getConfig (annexConfig "http-headers-command") ""
 	if (null cmd)
 		then fromRepo $ Git.Config.getList "annex.http-headers"
 		else lines . snd <$> liftIO (pipeFrom "sh" ["-c", cmd])