add uuid

.gitattributes

@@ -0,0 +1 @@
+.git-annex/*.log merge=union

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

GitRepo.hs

@@ -16,6 +16,7 @@ module GitRepo (
 	gitConfig,
 	gitAdd,
 	gitRm,
+	gitRun,
 	gitAttributes
 ) where
 
@@ -128,11 +129,11 @@ gitRelative repo file = drop (length absrepo) absfile
 
 {- Stages a changed/new file in git's index. -}
 gitAdd :: GitRepo -> FilePath -> IO ()
-gitAdd repo file = runGit repo ["add", file]
+gitAdd repo file = gitRun repo ["add", file]
 
 {- Removes a file. -}
 gitRm :: GitRepo -> FilePath -> IO ()
-gitRm repo file = runGit repo ["rm", file]
+gitRm repo file = gitRun repo ["rm", file]
 
 {- Constructs a git command line operating on the specified repo. -}
 gitCommandLine :: GitRepo -> [String] -> [String]
@@ -141,8 +142,8 @@ gitCommandLine repo params = assertlocal repo $
 	["--git-dir="++(gitDir repo), "--work-tree="++(top repo)] ++ params
 
 {- Runs git in the specified repo. -}
-runGit :: GitRepo -> [String] -> IO ()
-runGit repo params = assertlocal repo $ do
+gitRun :: GitRepo -> [String] -> IO ()
+gitRun repo params = assertlocal repo $ do
 	r <- executeFile "git" True (gitCommandLine repo params) Nothing
 	return ()