run git status before enabling clean filter

Avoids annex.largefiles inconsitency and also avoids a lot of
unneccessary calls to the clean filter when a large repo's clone
is being initialized.

This commit was supported by the NSF-funded DataLad project.

Config/Smudge.hs

@@ -0,0 +1,41 @@
+{- Git smudge filter configuration
+ -
+ - Copyright 2011-2018 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Config.Smudge where
+
+import Annex.Common
+import qualified Annex
+import qualified Git
+import qualified Git.Command
+import Config
+
+configureSmudgeFilter :: Annex ()
+configureSmudgeFilter = do
+	-- If this is run in a newly cloned repository, git may not have
+	-- cached file information in the index yet, and so after
+	-- configuring the clean filter, the next git status would want to
+	-- run it on every file. That is expensive and can also result in
+	-- unexpected changes when the file is checked into git or annex
+	-- counter to the annex.largefiles configuration.
+	-- Avoid that problem by running git status now.
+	inRepo $ Git.Command.runQuiet [Param "status", Param "--porcelain"]
+
+	setConfig (ConfigKey "filter.annex.smudge") "git-annex smudge %f"
+	setConfig (ConfigKey "filter.annex.clean") "git-annex smudge --clean %f"
+	lf <- Annex.fromRepo Git.attributesLocal
+	gf <- Annex.fromRepo Git.attributes
+	lfs <- readattr lf
+	gfs <- readattr gf
+	liftIO $ unless ("filter=annex" `isInfixOf` (lfs ++ gfs)) $ do
+		createDirectoryIfMissing True (takeDirectory lf)
+		writeFile lf (lfs ++ "\n" ++ stdattr)
+  where
+	readattr = liftIO . catchDefaultIO "" . readFileStrict
+	stdattr = unlines
+		[ "* filter=annex"
+		, ".* !filter"
+		]