better streaming while encrypting/decrypting

Both the directory and webdav special remotes used to have to buffer
the whole file contents before it could be decrypted, as they read
from chunks. Now the chunks are streamed through gpg with no buffering.

Remote/WebDAV.hs

@@ -93,8 +93,8 @@ storeEncrypted :: Remote -> (Cipher, Key) -> Key -> MeterUpdate -> Annex Bool
 storeEncrypted r (cipher, enck) k _p = davAction r False $ \(baseurl, user, pass) -> do
 	let url = davLocation baseurl enck
 	f <- inRepo $ gitAnnexLocation k
-	liftIO $ withEncryptedContent cipher (L.readFile f) $
-		storeHelper r url user pass
+	liftIO $ encrypt cipher (feedFile f) $
+		readBytes $ storeHelper r url user pass
 
 storeHelper :: Remote -> DavUrl -> DavUser -> DavPass -> L.ByteString -> IO Bool
 storeHelper r urlbase user pass b = catchBoolIO $ do
@@ -133,18 +133,20 @@ retrieveEncrypted :: Remote -> (Cipher, Key) -> Key -> FilePath -> Annex Bool
 retrieveEncrypted r (cipher, enck) k d = metered Nothing k $ \meterupdate ->
 	davAction r False $ \(baseurl, user, pass) -> liftIO $ catchBoolIO $
 		withStoredFiles r enck baseurl user pass onerr $ \urls -> do
-			withDecryptedContent cipher (L.concat <$> feeder user pass urls []) $
-				meteredWriteFile meterupdate d
+			decrypt cipher (feeder user pass urls) $
+				readBytes $ meteredWriteFile meterupdate d
 			return True
   where
 	onerr _ = return False
 
-	feeder _ _ [] c = return $ reverse c
-	feeder user pass (url:urls) c = do
+	feeder _ _ [] _ = noop
+	feeder user pass (url:urls) h = do
 		mb <- davGetUrlContent url user pass
 		case mb of
 			Nothing -> throwIO "download failed"
-			Just b -> feeder user pass urls (b:c)
+			Just b -> do
+				L.hPut h b
+				feeder user pass urls h
 
 remove :: Remote -> Key -> Annex Bool
 remove r k = davAction r False $ \(baseurl, user, pass) -> liftIO $ do