fix breakage in wormhole's sendFile

Commit ff0927bde9 broke this, it made it
try to read all of the input before looking for the code. But, wormhole
keeps running until it sends the file, so that caused a deadlock. Oops.

Sponsored-by: Luke Shumaker on Patreon

Utility/MagicWormhole.hs

@@ -120,16 +120,21 @@ sendFile f (CodeObserver observer) ps = do
 		return (inout || inerr)
   where
 	p = wormHoleProcess (ps ++ [Param "send", File f])
-	findcode ph h = findcode' =<< getwords ph h []
+	findcode ph h = hGetLineUntilExitOrEOF ph h >>= \case
+		Nothing -> return False
+		Just l -> ifM (findcode' (words l))
+			( drain ph h >> return True
+			, findcode ph h
+			)
 	findcode' [] = return False
 	findcode' (w:ws) = case mkCode w of
 		Just code -> do
 			_ <- tryPutMVar observer code
 			return True
 		Nothing -> findcode' ws
-	getwords ph h c = hGetLineUntilExitOrEOF ph h >>= \case
-		Nothing -> return $ concatMap words $ reverse c
-		Just l -> getwords ph h (l:c)
+	drain ph h = hGetLineUntilExitOrEOF ph h >>= \case
+		Just _ -> drain ph h
+		Nothing -> return ()
 
 -- | Receives a file. Once the receive is under way, the Code will be
 -- read from the CodeProducer, and fed to wormhole on stdin.