post-recive hook to make updateInstead work in direct mode and adjusted branches

* Added post-recieve hook, which makes updateInstead work with direct
  mode and adjusted branches.
* init: Set up the post-receive hook.

This commit was sponsored by Fernando Jimenez on Patreon.

Git/ConfigTypes.hs

@@ -0,0 +1,40 @@
+{- git config types
+ -
+ - Copyright 2012, 2017 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Git.ConfigTypes where
+
+import Data.Char
+
+import Common
+import Git
+import qualified Git.Config
+
+data SharedRepository = UnShared | GroupShared | AllShared | UmaskShared Int
+	deriving (Eq)
+
+getSharedRepository :: Repo -> SharedRepository
+getSharedRepository r =
+	case map toLower $ Git.Config.get "core.sharedrepository" "" r of
+		"1" -> GroupShared
+		"2" -> AllShared
+		"group" -> GroupShared
+		"true" -> GroupShared
+		"all" -> AllShared
+		"world" -> AllShared
+		"everybody" -> AllShared
+		v -> maybe UnShared UmaskShared (readish v)
+
+data DenyCurrentBranch = UpdateInstead | RefusePush | WarnPush | IgnorePush
+	deriving (Eq)
+
+getDenyCurrentBranch :: Repo -> DenyCurrentBranch
+getDenyCurrentBranch r =
+	case map toLower $ Git.Config.get "receive.denycurrentbranch" "" r of
+		"updateinstead" -> UpdateInstead
+		"warn" -> WarnPush
+		"ignore" -> IgnorePush
+		_ -> RefusePush