Add progress bar display to the directory special remote.

So far I've only written progress bars for sending files, not yet
receiving.

No longer uses external cp at all. ByteString IO is fast enough.

Messages.hs

@@ -10,6 +10,8 @@ module Messages (
 	showNote,
 	showAction,
 	showProgress,
+	metered,
+	MeterUpdate,
 	showSideAction,
 	showOutput,
 	showLongNote,
@@ -29,9 +31,13 @@ module Messages (
 ) where
 
 import Text.JSON
+import Data.Progress.Meter
+import Data.Progress.Tracker
+import Data.Quantity
 
 import Common
 import Types
+import Types.Key
 import qualified Annex
 import qualified Messages.JSON as JSON
 
@@ -46,10 +52,29 @@ showNote s = handle (JSON.note s) $
 showAction :: String -> Annex ()
 showAction s = showNote $ s ++ "..."
 
+{- Progress dots. -}
 showProgress :: Annex ()
 showProgress = handle q $
 	flushed $ putStr "."
 
+{- Shows a progress meter while performing a transfer of a key.
+ - The action is passed a callback to use to update the meter. -}
+type MeterUpdate = Integer -> IO ()
+metered :: Key -> (MeterUpdate -> Annex a) -> Annex a
+metered key a = Annex.getState Annex.output >>= go (keySize key)
+	where
+		go (Just size) Annex.NormalOutput = do
+			progress <- liftIO $ newProgress "" size
+			meter <- liftIO $ newMeter progress "B" 20 (renderNums binaryOpts 1)
+			showOutput
+			liftIO $ displayMeter stdout meter
+			r <- a $ \n -> liftIO $ do
+				incrP progress n
+				displayMeter stdout meter
+			liftIO $ clearMeter stdout meter
+			return r	
+                go _ _ = a (const $ return ())
+
 showSideAction :: String -> Annex ()
 showSideAction s = handle q $
 	putStrLn $ "(" ++ s ++ "...)"