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- {-# LANGUAGE OverloadedStrings #-}
- module Walrus.Backend (
- Backend(..),
- module Walrus.Backend.Metadata,
- parseBackend,
- runBackend
- ) where
- import qualified Data.Attoparsec.ByteString.Char8 as A
- import qualified Data.Attoparsec.ByteString.Lazy as LA
- import Data.Attoparsec.ByteString.Char8.Extras
- import qualified Data.ByteString.Lazy as LBS
- import qualified Data.Char as C
- import Data.Text.IsText
- import Walrus.Backend.Metadata
- import Control.Applicative
- import Network
- import System.IO
- import qualified System.Process as P
- data Backend = TCPBackend String Int | UnixSocketBackend String |
- ExecBackend String [String] deriving (Show, Read, Ord, Eq)
- parseBackend :: A.Parser Backend
- parseBackend = do
- A.choice [
- do
- tp "tcp"
- h <- tillSpace
- p <- A.decimal
- return $ TCPBackend h p,
- do
- tp "unix"
- tp "socket"
- p <- qStr
- return $ UnixSocketBackend p,
- do
- tp "exec"
- f <- qStr
- pp <- parseParameters
- return $ ExecBackend f pp
- ]
- where
- tp t = do
- skipHorizontalSpace
- A.stringCI t
- skipHorizontalSpace
- tillSpace :: A.Parser String
- tillSpace = fromText <$> A.takeTill C.isSpace
- qStr :: A.Parser String
- qStr = fromText <$> quotedString '\\' " " ""
- parseParameters = A.many' $ do
- p <- qStr
- skipHorizontalSpace
- return p
- runBackend :: Backend -> (Metadata, LBS.ByteString) -> IO (Either String (Metadata, LBS.ByteString))
- runBackend b (m, qdt) = case renderMetadata m of
- Nothing -> return $ Left "Metadata error"
- Just rm -> do
- edt' <- intBk b $ LBS.concat [
- fromText rm,
- "\r\n",
- qdt]
- case LA.parse repParse edt' of
- LA.Fail _ _ e -> return $ Left e
- LA.Done edt m' -> return $ Right (m', edt)
- where
- intBk :: Backend -> LBS.ByteString -> IO LBS.ByteString
- intBk (TCPBackend h p) = runTcp h p
- intBk (UnixSocketBackend f) = runUnix f
- intBk (ExecBackend f aa) = runExec f aa
- repParse = do
- m' <- parseMetadata
- A.endOfLine
- return m'
- runTcp :: String -> Int -> LBS.ByteString -> IO LBS.ByteString
- runTcp host port dt = do
- h <- connectTo host (PortNumber . fromIntegral $ port)
- bkgTrans h dt
- runUnix :: String -> LBS.ByteString -> IO LBS.ByteString
- runUnix path dt = do
- h <- connectTo "localhost" (UnixSocket path)
- bkgTrans h dt
- bkgTrans :: Handle -> LBS.ByteString -> IO LBS.ByteString
- bkgTrans h dt = do
- hSetNewlineMode h noNewlineTranslation
- LBS.hPut h dt
- hFlush h
- LBS.hGetContents h
- runExec :: String -> [String] -> LBS.ByteString -> IO LBS.ByteString
- runExec f args dt = do
- (Just i, Just o, _, _) <- P.createProcess (
- (P.proc f args){P.std_in=P.CreatePipe}{
- P.std_out=P.CreatePipe}{P.std_err=P.Inherit}
- )
- mapM (\h -> hSetNewlineMode h noNewlineTranslation) [i, o]
- LBS.hPut i dt
- hFlush i
- LBS.hGetContents o
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