Created
October 20, 2012 15:49
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Coroutine interface to Bash from Haskell.
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{-# LANGUAGE OverloadedStrings | |
, ScopedTypeVariables | |
, ParallelListComp | |
, TupleSections #-} | |
module CoBash where | |
import Control.Applicative | |
import Control.Concurrent | |
import Control.Concurrent.MVar | |
import Control.Exception | |
import Control.Monad | |
import Data.Bits | |
import Data.ByteString.Char8 (ByteString) | |
import qualified Data.ByteString.Char8 as Bytes | |
import Data.Maybe | |
import Data.Monoid | |
import qualified GHC.IO.Handle.FD | |
import System.IO | |
import System.IO.Error | |
import System.Process | |
import System.Posix.ByteString | |
import System.IO.Temp | |
import qualified Text.ShellEscape as Esc | |
start :: IO (Handle, Handle, Handle, ProcessHandle) | |
start = runInteractiveProcess "bash" [] Nothing (Just []) | |
query :: (Handle, Handle, Handle, ProcessHandle) -> ByteString | |
-> IO (ByteString, ByteString) | |
query (i, _, _, _) query = withFIFOs query' | |
where query' ofo efo = do | |
Bytes.hPut i cmd | |
hFlush i | |
[ob, eb] <- backgroundReadFIFOs [ofo, efo] | |
return (ob, eb) | |
where cmd = Bytes.unlines ["{", query, "} 1>" <> ofo <> " 2>" <> efo] | |
shutdown :: (Handle, Handle, Handle, ProcessHandle) -> IO () | |
shutdown (i, _, _, p) = () <$ hClose i <* waitForProcess p | |
openFIFO path = GHC.IO.Handle.FD.openFileBlocking (Bytes.unpack path) ReadMode | |
-- | Run an IO action with two FIFOs in scope, which will removed after it | |
-- completes. | |
withFIFOs :: (RawFilePath -> RawFilePath -> IO a) -> IO a | |
withFIFOs m = withSystemTempDirectory "cobash." m' | |
where m' = (uncurry m =<<) . mk . Bytes.pack | |
mk d = (o, e) <$ (createNamedPipe o mode >> createNamedPipe e mode) | |
where (o, e) = (d <> "/o", d <> "/e") | |
mode = ownerReadMode .|. ownerWriteMode .|. namedPipeMode | |
drainFIFO :: ByteString -> IO ByteString | |
drainFIFO path = do | |
(i, o, e, p) <- bash ["-c", "exec cat <"<>(Bytes.unpack path)] | |
hClose i | |
hClose e | |
Bytes.hGetContents o <* waitForProcess p | |
backgroundReadFIFOs theFIFOs = do | |
cells <- sequence (newEmptyMVar <$ theFIFOs) | |
sequence_ [ forkIO (drainFIFO p >>= putMVar c) | p <- theFIFOs | c <- cells ] | |
sequence (takeMVar <$> cells) | |
bash args = runInteractiveProcess "bash" args Nothing (Just []) |
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