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|
{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}
module ProcessUtils
( ExitCode(ExitFailure,ExitSuccess)
, systemEnv
, readPipe
, readProcessWithErrorH
, runExternal
) where
import GHC.IO.Exception ( ioException, IOErrorType(..) )
import System.FilePath
import System.Directory
import System.Process
import System.Posix.Signals
import System.Process.Internals (runGenProcess_,defaultSignal)
import System.Environment
import Data.Maybe ( isNothing, fromMaybe )
import System.IO.Error ( mkIOError, ioeSetErrorString )
import System.Exit ( ExitCode(..) )
import System.IO
import Control.Applicative
import Control.Exception (bracket)
import qualified Data.ByteString as S
-- | systemEnv
-- This is like System.Process.system except that it lets you set
-- some environment variables.
systemEnv :: [(String, String)] -> String -> IO ExitCode
systemEnv _ "" =
ioException (ioeSetErrorString (mkIOError InvalidArgument "system" Nothing Nothing) "null command")
systemEnv vars cmd = do
env0 <- getEnvironment
let env1 = filter (isNothing . flip lookup vars . fst) env0
env = vars ++ env1
syncProcess "system" $ (shell cmd) {env=Just env}
where
-- This is a non-exported function from System.Process
syncProcess fun c = do
-- The POSIX version of system needs to do some manipulation of signal
-- handlers. Since we're going to be synchronously waiting for the child,
-- we want to ignore ^C in the parent, but handle it the default way
-- in the child (using SIG_DFL isn't really correct, it should be the
-- original signal handler, but the GHC RTS will have already set up
-- its own handler and we don't want to use that).
old_int <- installHandler sigINT Ignore Nothing
old_quit <- installHandler sigQUIT Ignore Nothing
(_,_,_,p) <- runGenProcess_ fun c
(Just defaultSignal) (Just defaultSignal)
r <- waitForProcess p
_ <- installHandler sigINT old_int Nothing
_ <- installHandler sigQUIT old_quit Nothing
return r
-- | readPipe
--
-- This is like System.Process.readProcess but instead of a single
-- command with arguments, you pass it a list which it then executes
-- piping the the output from the prior command into the input for
-- the next command. Like readProcess the next parameter is a string
-- which is sent as input into the initial standard in.
--
-- > readPipe [("grep",["HostConfig"]),("wc",["-l"]) =<< readFile "input"
--
-- is equivalent to shell code:
--
-- > grep HostConfig input | wc -l
--
readPipe :: [(FilePath,[String])] -> String -> IO String
readPipe [(cmd,args)] input = readProcess cmd args input
readPipe ((cmd,args):xs) stdin0 = do
let p = (shell cmd) { std_in = CreatePipe
, std_out = CreatePipe
, std_err = CreatePipe
, cmdspec = RawCommand cmd args
}
(Just sinh,Just sout,Just serr, ph) <- createProcess p
hPutStr sinh stdin0
hClose sinh
readPipe0 xs sout
where
readPipe0 :: [(FilePath,[String])] -> Handle -> IO String
readPipe0 ((cmd,args):xs) stdin0 = do
let p = (shell cmd)
{ std_in = UseHandle stdin0
, std_out = CreatePipe
, std_err = CreatePipe
, cmdspec = RawCommand cmd args
}
(Nothing,Just sout,Just serr, ph) <- createProcess p
readPipe0 xs sout
readPipe0 [] h = hGetContents h
readProcessWithErrorH :: FilePath -> [String] -> String -> Handle -> IO String
readProcessWithErrorH cmd args stdin erH = do
let p = (shell cmd) { std_in = CreatePipe
, std_out = CreatePipe
, std_err = UseHandle erH
, cmdspec = RawCommand cmd args
}
bracket (createProcess p)
(\(Just sinh,Just sout,_, ph) ->
mapM_ hClose [sinh,sout] )
(\(Just sinh,Just sout,_, ph) -> do
hPutStr sinh stdin
hClose sinh
hGetContents sout )
-- | run an external command.
--
-- Arguments:
--
-- [ cmd ] command to run
--
-- [ input ] input to command (if any)
--
-- Returns:
--
-- [ code ] exit code returned by command
--
-- [ output ] captured stdout of command
--
-- [ err ] captured stderr of command
runExternal :: String -> Maybe String -> IO (Int,(S.ByteString,S.ByteString))
runExternal cmd input = do
cwd <- getCurrentDirectory
{-
putStr $ takeFileName cwd ++ "> " ++ cmd
++ case input of
Nothing -> "\n"
Just s -> " <<EOF\n" ++ s ++ "EOF\n"
-}
let p = (shell cmd) { std_in = maybe Inherit (const CreatePipe) input
, std_out = CreatePipe
, std_err = CreatePipe }
(mb_in,mb_out,mb_err,process) <- createProcess p
case mb_in of
Nothing -> return ()
Just hin -> hPutStr hin (fromMaybe "" input) >> hClose hin
out <- case mb_out of
Just hout -> S.hGetContents hout
Nothing -> return ""
err <- case mb_err of
Just herr -> S.hGetContents herr
Nothing -> return ""
code <- do
c <- waitForProcess process
return $ case c of
ExitSuccess -> 0
ExitFailure x -> x
return (code,(out,err))
|
