forgot to add this new source file

Logs/Config.hs

@@ -0,0 +1,61 @@
+{- git-annex config log
+ -
+ - Copyright 2017 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Logs.Config (
+	ConfigName,
+	ConfigValue,
+	setGlobalConfig,
+	unsetGlobalConfig,
+	getGlobalConfig,
+	loadGlobalConfig,
+) where
+
+import Annex.Common
+import qualified Annex
+import Logs
+import Logs.MapLog
+import qualified Annex.Branch
+
+import Data.Time.Clock.POSIX
+import qualified Data.Map as M
+
+type ConfigName = String
+type ConfigValue = String
+
+setGlobalConfig :: ConfigName -> ConfigValue -> Annex ()
+setGlobalConfig name new = do
+	curr <- getGlobalConfig name
+	when (curr /= Just new) $
+		setGlobalConfig' name new
+
+setGlobalConfig' :: ConfigName -> ConfigValue -> Annex ()
+setGlobalConfig' name new = do
+	now <- liftIO getPOSIXTime
+	Annex.Branch.change configLog $ 
+		showMapLog id id . changeMapLog now name new . parseGlobalConfig
+
+unsetGlobalConfig :: ConfigName -> Annex ()
+unsetGlobalConfig name = do
+	curr <- getGlobalConfig name
+	when (curr /= Nothing) $
+		setGlobalConfig' name "" -- set to empty string to unset
+
+getGlobalConfig :: ConfigName -> Annex (Maybe ConfigValue)
+getGlobalConfig name = do
+	m <- maybe loadGlobalConfig return
+		=<< Annex.getState Annex.globalconfig
+	return (M.lookup name m)
+
+parseGlobalConfig :: String -> MapLog ConfigName ConfigValue
+parseGlobalConfig = parseMapLog Just Just
+
+loadGlobalConfig :: Annex (M.Map ConfigName ConfigValue)
+loadGlobalConfig = do
+	m <- M.filter (not . null) . simpleMap . parseGlobalConfig
+		<$> Annex.Branch.get configLog
+	Annex.changeState $ \s -> s { Annex.globalconfig = Just m }
+	return m