add uuid

Annex.hs

@@ -10,6 +10,8 @@ module Annex (
 
 import System.Posix.Files
 import System.Directory
+import System.Cmd.Utils
+import System.IO
 import GitRepo
 import Utility
 import Locations
@@ -84,6 +86,13 @@ unannexFile state file = do
 {- Sets up a git repo for git-annex. May be called repeatedly. -}
 gitPrep :: GitRepo -> IO ()
 gitPrep repo = do
+	-- Make sure that the repo has an annex.uuid setting.
+	if ("" == gitConfig repo "annex.uuid" "")
+		then do
+			uuid <- genUUID
+			gitRun repo ["config", "annex.uuid", uuid]
+		else return ()
+
 	-- configure git to use union merge driver on state files
 	let attrLine = stateLoc ++ "/*.log merge=union"
 	let attributes = gitAttributes repo
@@ -99,3 +108,9 @@ gitPrep repo = do
 					appendFile attributes $ attrLine ++ "\n"
 					gitAdd repo attributes
 				else return ()
+
+{- Generates a UUID. There is a library for this, but it's not packaged,
+ - so use the command line tool. -}
+genUUID :: IO String
+genUUID = do
+	pOpen ReadFromPipe "uuid" ["-m"] $ \h -> hGetLine h