Support git's core.sharedRepository configuration

This is incomplete, it does not honor it yet for hash directories
and other annex bookkeeping files. Some of that is not needed for a bare
repo; some of it may be.

Git/SharedRepository.hs

@@ -0,0 +1,27 @@
+{- git core.sharedRepository handling
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Git.SharedRepository where
+
+import Data.Char
+
+import Common
+import Git
+import qualified Git.Config
+
+data SharedRepository = UnShared | GroupShared | AllShared | UmaskShared Int
+
+getSharedRepository :: Repo -> SharedRepository
+getSharedRepository r =
+	case map toLower $ Git.Config.get "core.sharedrepository" "" r of
+		"1" -> GroupShared
+		"group" -> GroupShared
+		"true" -> GroupShared
+		"all" -> AllShared
+		"world" -> AllShared
+		"everybody" -> AllShared
+		v -> maybe UnShared UmaskShared (readish v)