git-annex/Utility/Process/Transcript.hs
2018-03-15 14:47:54 -04:00

93 lines
2.5 KiB
Haskell

{- Process transcript
-
- Copyright 2012-2018 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.Process.Transcript where
import Utility.Process
import System.IO
import System.Exit
import Control.Concurrent
import qualified Control.Exception as E
import Control.Monad
#ifndef mingw32_HOST_OS
import qualified System.Posix.IO
#else
import Control.Applicative
#endif
import Data.Maybe
import Prelude
-- | Runs a process and returns a transcript combining its stdout and
-- stderr, and whether it succeeded or failed.
processTranscript :: String -> [String] -> (Maybe String) -> IO (String, Bool)
processTranscript cmd opts = processTranscript' (proc cmd opts)
-- | Also feeds the process some input.
processTranscript' :: CreateProcess -> Maybe String -> IO (String, Bool)
processTranscript' cp input = do
(t, c) <- processTranscript'' cp input
return (t, c == ExitSuccess)
processTranscript'' :: CreateProcess -> Maybe String -> IO (String, ExitCode)
processTranscript'' cp input = do
#ifndef mingw32_HOST_OS
{- This implementation interleves stdout and stderr in exactly the order
- the process writes them. -}
(readf, writef) <- System.Posix.IO.createPipe
readh <- System.Posix.IO.fdToHandle readf
writeh <- System.Posix.IO.fdToHandle writef
p@(_, _, _, pid) <- createProcess $ cp
{ std_in = if isJust input then CreatePipe else Inherit
, std_out = UseHandle writeh
, std_err = UseHandle writeh
}
hClose writeh
get <- mkreader readh
writeinput input p
transcript <- get
#else
{- This implementation for Windows puts stderr after stdout. -}
p@(_, _, _, pid) <- createProcess $ cp
{ std_in = if isJust input then CreatePipe else Inherit
, std_out = CreatePipe
, std_err = CreatePipe
}
getout <- mkreader (stdoutHandle p)
geterr <- mkreader (stderrHandle p)
writeinput input p
transcript <- (++) <$> getout <*> geterr
#endif
code <- waitForProcess pid
return (transcript, code)
where
mkreader h = do
-- Start consuming the output immediately, because the
-- process may block on reading input until some
-- of its output is consumed.
s <- hGetContents h
v <- newEmptyMVar
void $ forkIO $ do
-- Wait for output to be fully consumed.
void $ E.evaluate (length s)
putMVar v ()
return $ do
takeMVar v
return s
writeinput (Just s) p = do
let inh = stdinHandle p
unless (null s) $ do
hPutStr inh s
hFlush inh
hClose inh
writeinput Nothing _ = return ()