add per-remote-type info

Now `git annex info $remote` shows info specific to the type of the remote,
for example, it shows the rsync url.

Remote types that support encryption or chunking also include that in their
info.

This commit was sponsored by Ævar Arnfjörð Bjarmason.

Remote/Helper/Chunked.hs

@@ -8,6 +8,7 @@
 module Remote.Helper.Chunked (
 	ChunkSize,
 	ChunkConfig(..),
+	describeChunkConfig,
 	getChunkConfig,
 	storeChunks,
 	removeChunks,
@@ -34,6 +35,14 @@ data ChunkConfig
 	| LegacyChunks ChunkSize
 	deriving (Show)
 
+describeChunkConfig :: ChunkConfig -> String
+describeChunkConfig NoChunks = "none"
+describeChunkConfig (UnpaddedChunks sz) = describeChunkSize sz ++ "chunks"
+describeChunkConfig (LegacyChunks sz) = describeChunkSize sz ++ " chunks (old style)"
+
+describeChunkSize :: ChunkSize -> String
+describeChunkSize sz = roughSize storageUnits False (fromIntegral sz)
+
 noChunks :: ChunkConfig -> Bool
 noChunks NoChunks = True
 noChunks _ = False

Remote/Helper/Encryptable.hs

@@ -16,6 +16,7 @@ module Remote.Helper.Encryptable (
 	cipherKey,
 	storeCipher,
 	extractCipher,
+	describeEncryption,
 ) where
 
 import qualified Data.Map as M
@@ -157,3 +158,10 @@ extractCipher c = case (M.lookup "cipher" c,
 	_ -> Nothing
   where
 	readkeys = KeyIds . split ","
+
+describeEncryption :: RemoteConfig -> String
+describeEncryption c = case extractCipher c of
+	Nothing -> "not encrypted"
+	(Just (SharedCipher _)) -> "encrypted (encryption key stored in git repository)"
+	(Just (EncryptedCipher _ _ (KeyIds { keyIds = ks }))) ->
+		"encrypted (to gpg keys: " ++ unwords ks ++ ")"

Remote/Helper/Git.hs

@@ -30,3 +30,8 @@ guardUsable :: Git.Repo -> Annex a -> Annex a -> Annex a
 guardUsable r fallback a
 	| Git.repoIsLocalUnknown r = fallback
 	| otherwise = a
+
+gitRepoInfo :: Git.Repo -> [(String, String)]
+gitRepoInfo r =
+	[ ("repository location", Git.repoLocation r)
+	]

Remote/Helper/Special.hs

@@ -168,6 +168,12 @@ specialRemote' cfg c preparestorer prepareretriever prepareremover preparecheckp
 			(cost baser)
 			(const $ cost baser + encryptedRemoteCostAdj)
 			(extractCipher c)
+		, getInfo = do
+			l <- getInfo baser
+			return $ l ++
+				[ ("encryption", describeEncryption c)
+				, ("chunking", describeChunkConfig (chunkConfig cfg))
+				]
 		}
 	cip = cipherKey c
 	gpgopts = getGpgEncParams encr