git-annex/Annex/Multicast.hs

{- git-annex multicast receive callback
 -
 - Copyright 2017 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

{-# LANGUAGE CPP #-}

module Annex.Multicast where

import Config.Files
import Utility.Env
import Utility.PartialPrelude

import System.Process
import System.IO
import GHC.IO.Handle.FD
#if ! MIN_VERSION_process(1,4,2)
import System.Posix.IO (handleToFd)
#endif
import Control.Applicative
import Prelude

multicastReceiveEnv :: String
multicastReceiveEnv = "GIT_ANNEX_MULTICAST_RECEIVE"

multicastCallbackEnv :: IO (FilePath, [(String, String)], Handle)
multicastCallbackEnv = do
	gitannex <- readProgramFile
#if MIN_VERSION_process(1,4,2)
	-- This will even work on Windows
	(rfd, wfd) <- createPipeFd
	rh <- fdToHandle rfd
#else
	(rh, wh) <- createPipe
	wfd <- handleToFd wh
#endif
	environ <- addEntry multicastReceiveEnv (show wfd) <$> getEnvironment
	return (gitannex, environ, rh)

-- This is run when uftpd has received a file. Rather than move
-- the file into the annex here, which would require starting up the
-- Annex monad, parsing git config, and verifying the content, simply
-- output to the specified FD the filename. This keeps the time
-- that uftpd is not receiving the next file as short as possible.
runMulticastReceive :: [String] -> String -> IO ()
runMulticastReceive ("-I":_sessionid:fs) hs = case readish hs of
	Just fd -> do
		h <- fdToHandle fd
		mapM_ (hPutStrLn h) fs
		hClose h
	Nothing -> return ()
runMulticastReceive _ _ = return ()