implement Unavilable for borg bup ddar directory rsync

Only gcrypt remains to add support for. (Well, possibly also adb?)

Sponsored-by: Luke T. Shumaker on Patreon

Remote/Helper/Path.hs

@@ -0,0 +1,19 @@
+{- Utilities for remotes located in a path in the filesystem.
+ -
+ - Copyright 2023 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU AGPL version 3 or higher.
+ -}
+
+module Remote.Helper.Path where
+
+import Annex.Common
+import Types.Availability
+
+checkPathAvailability :: Bool -> FilePath -> Annex Availability
+checkPathAvailability islocal d
+	| not islocal = return GloballyAvailable
+	| otherwise = ifM (liftIO $ doesDirectoryExist d)
+		( return LocallyAvailable
+		, return Unavailable
+		)