Add annex.version, which will be used to automate upgrades.

Annex.hs

@@ -19,7 +19,8 @@ module Annex (
 	flagGet,
 	Flag(..),
 	queue,
-	queueGet
+	queueGet,
+	setConfig
 ) where
 
 import Control.Monad.State
@@ -118,3 +119,12 @@ queueGet :: Annex GitQueue.Queue
 queueGet = do
 	state <- get
 	return (Internals.repoqueue state)
+
+{- Changes a git config setting in both internal state and .git/config -}
+setConfig :: String -> String -> Annex ()
+setConfig key value = do
+	g <- Annex.gitRepo
+	liftIO $ Git.run g ["config", key, value]
+	-- re-read git config and update the repo's state
+	g' <- liftIO $ Git.configRead g Nothing
+	Annex.gitRepoChange g'

Core.hs

@@ -46,6 +46,7 @@ tryRun' _ errnum [] =
 startup :: Annex Bool
 startup = do
 	prepUUID
+	autoUpgrade
 	return True
 
 {- When git-annex is done, it runs this. -}
@@ -151,6 +152,21 @@ getViaTmp key action = do
 			-- to resume its transfer
 			return False
 
+{- Uses the annex.version git config setting to automate upgrades. -}
+autoUpgrade :: Annex ()
+autoUpgrade = do
+	g <- Annex.gitRepo
+
+	case Git.configGet g field "0" of
+		"0" -> do -- before there was repo versioning
+			setVersion
+		v | v == currentVersion -> return ()
+		_ -> error "this version of git-annex is too old for this git repository!"
+	where
+		currentVersion = "1"
+		setVersion = Annex.setConfig field currentVersion
+		field = "annex.version"
+
 {- Output logging -}
 verbose :: Annex () -> Annex ()
 verbose a = do

UUID.hs

@@ -65,7 +65,7 @@ getUUID r = do
 	where
 		uncached = Git.configGet r "annex.uuid" ""
 		cached g = Git.configGet g cachekey ""
-		updatecache g u = when (g /= r) $ setConfig cachekey u
+		updatecache g u = when (g /= r) $ Annex.setConfig cachekey u
 		cachekey = "remote." ++ (Git.repoRemoteName r) ++ ".annex-uuid"
 
 {- Make sure that the repo has an annex.uuid setting. -}
@@ -75,16 +75,7 @@ prepUUID = do
 	u <- getUUID g
 	when ("" == u) $ do
 		uuid <- liftIO $ genUUID
-		setConfig configkey uuid
-
-{- Changes a git config setting in both internal state and .git/config -}
-setConfig :: String -> String -> Annex ()
-setConfig key value = do
-	g <- Annex.gitRepo
-	liftIO $ Git.run g ["config", key, value]
-	-- re-read git config and update the repo's state
-	g' <- liftIO $ Git.configRead g Nothing
-	Annex.gitRepoChange g'
+		Annex.setConfig configkey uuid
 
 {- Filters a list of repos to ones that have listed UUIDs. -}
 reposByUUID :: [Git.Repo] -> [UUID] -> Annex [Git.Repo]

debian/changelog

@@ -1,6 +1,7 @@
 git-annex (0.04) UNRELEASED; urgency=low
 
   * Add build dep on libghc6-testpack-dev.
+  * Add annex.version, which will be used to automate upgrades.
 
  -- Joey Hess <joeyh@debian.org>  Mon, 08 Nov 2010 12:36:39 -0400
 

doc/git-annex.mdwn

@@ -207,6 +207,8 @@ Here are all the supported configuration settings.
   to talk to this repository.
 * `annex.scp-options` and `annex.ssh-options` -- Default scp and ssh
   options to use if a remote does not have specific options.
+* `annex.version` -- Automatically maintained, and used to automate upgrades
+  between versions.
 
 The backend used when adding a new file to the annex can be configured
 on a per-file-type basis via the `.gitattributes` file. In the file,