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|
{- System.Process enhancements, including additional ways of running
- processes, and logging.
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE Rank2Types #-}
module Utility.Process (
module X,
CreateProcess,
StdHandle(..),
readProcessEnv,
forceSuccessProcess,
checkSuccessProcess,
createProcessSuccess,
createProcessChecked,
createBackgroundProcess,
withHandle,
withBothHandles,
createProcess,
runInteractiveProcess,
writeReadProcess,
readProcess
) where
import qualified System.Process
import System.Process as X hiding (CreateProcess(..), createProcess, runInteractiveProcess, readProcess, readProcessWithExitCode, system, rawSystem, runInteractiveCommand, runProcess)
import System.Process hiding (createProcess, runInteractiveProcess, readProcess)
import System.Exit
import System.IO
import System.Log.Logger
import Utility.Misc
type CreateProcessRunner = forall a. CreateProcess -> ((Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle) -> IO a) -> IO a
data StdHandle = StdinHandle | StdoutHandle | StderrHandle
deriving (Eq)
{- Like readProcess, but allows specifying the environment, and does
- not mess with stdin. -}
readProcessEnv :: FilePath -> [String] -> Maybe [(String, String)] -> IO String
readProcessEnv cmd args environ =
withHandle StdoutHandle createProcessSuccess p $ \h -> do
output <- hGetContentsStrict h
hClose h
return output
where
p = (proc cmd args)
{ std_out = CreatePipe
, env = environ
}
{- Waits for a ProcessHandle, and throws an exception if the process
- did not exit successfully. -}
forceSuccessProcess :: CreateProcess -> ProcessHandle -> IO ()
forceSuccessProcess p pid = do
code <- waitForProcess pid
case code of
ExitSuccess -> return ()
ExitFailure n -> error $ showCmd p ++ " exited " ++ show n
{- Waits for a ProcessHandle and returns True if it exited successfully. -}
checkSuccessProcess :: ProcessHandle -> IO Bool
checkSuccessProcess pid = do
code <- waitForProcess pid
return $ code == ExitSuccess
{- Runs createProcess, then an action on its handles, and then
- forceSuccessProcess. -}
createProcessSuccess :: CreateProcessRunner
createProcessSuccess p a = createProcessChecked (forceSuccessProcess p) p a
{- Runs createProcess, then an action on its handles, and then
- an action on its exit code. -}
createProcessChecked :: (ProcessHandle -> IO b) -> CreateProcessRunner
createProcessChecked checker p a = do
t@(_, _, _, pid) <- createProcess p
r <- a t
_ <- checker pid
return r
{- Leaves the process running, suitable for lazy streaming.
- Note: Zombies will result, and must be waited on. -}
createBackgroundProcess :: CreateProcessRunner
createBackgroundProcess p a = a =<< createProcess p
{- Runs a CreateProcessRunner, on a CreateProcess structure, that
- is adjusted to pipe only from/to a single StdHandle, and passes
- the resulting Handle to an action. -}
withHandle
:: StdHandle
-> CreateProcessRunner
-> CreateProcess
-> (Handle -> IO a)
-> IO a
withHandle h creator p a = creator p' $ a . select
where
base = p
{ std_in = Inherit
, std_out = Inherit
, std_err = Inherit
}
(select, p')
| h == StdinHandle =
(stdinHandle, base { std_in = CreatePipe })
| h == StdoutHandle =
(stdoutHandle, base { std_out = CreatePipe })
| h == StderrHandle =
(stderrHandle, base { std_err = CreatePipe })
{- Like withHandle, but passes (stdin, stdout) handles to the action. -}
withBothHandles
:: CreateProcessRunner
-> CreateProcess
-> ((Handle, Handle) -> IO a)
-> IO a
withBothHandles creator p a = creator p' $ a . bothHandles
where
p' = p
{ std_in = CreatePipe
, std_out = CreatePipe
, std_err = Inherit
}
{- Extract a desired handle from createProcess's tuple.
- These partial functions are safe as long as createProcess is run
- with appropriate parameters to set up the desired handle.
- Get it wrong and the runtime crash will always happen, so should be
- easily noticed. -}
type HandleExtractor = (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle) -> Handle
stdinHandle :: HandleExtractor
stdinHandle (Just h, _, _, _) = h
stdinHandle _ = error "expected stdinHandle"
stdoutHandle :: HandleExtractor
stdoutHandle (_, Just h, _, _) = h
stdoutHandle _ = error "expected stdoutHandle"
stderrHandle :: HandleExtractor
stderrHandle (_, _, Just h, _) = h
stderrHandle _ = error "expected stderrHandle"
bothHandles :: (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle) -> (Handle, Handle)
bothHandles (Just hin, Just hout, _, _) = (hin, hout)
bothHandles _ = error "expected bothHandles"
{- Debugging trace for a CreateProcess. -}
debugProcess :: CreateProcess -> IO ()
debugProcess p = do
debugM "Utility.Process" $ unwords
[ action ++ ":"
, showCmd p
, maybe "" show (env p)
]
where
action
| piped (std_in p) && piped (std_out p) = "chat"
| piped (std_in p) = "feed"
| piped (std_out p) = "read"
| otherwise = "call"
piped Inherit = False
piped _ = True
{- Shows the command that a CreateProcess will run. -}
showCmd :: CreateProcess -> String
showCmd = go . cmdspec
where
go (ShellCommand s) = s
go (RawCommand c ps) = c ++ " " ++ show ps
{- Wrappers for System.Process functions that do debug logging.
-
- More could be added, but these are the only ones I usually need.
-}
createProcess :: CreateProcess -> IO (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle)
createProcess p = do
debugProcess p
System.Process.createProcess p
runInteractiveProcess
:: FilePath
-> [String]
-> Maybe FilePath
-> Maybe [(String, String)]
-> IO (Handle, Handle, Handle, ProcessHandle)
runInteractiveProcess f args c e = do
debugProcess $ (proc f args)
{ std_in = CreatePipe
, std_out = CreatePipe
, std_err = CreatePipe
}
System.Process.runInteractiveProcess f args c e
{- I think this is a more descriptive name than System.Process.readProcess. -}
writeReadProcess
:: FilePath
-> [String]
-> String
-> IO String
writeReadProcess f args input = do
debugProcess $ (proc f args) { std_out = CreatePipe, std_in = CreatePipe }
System.Process.readProcess f args input
{- Normally, when reading from a process, it does not need to be fed any
- input. -}
readProcess
:: FilePath
-> [String]
-> IO String
readProcess f args = do
debugProcess $ (proc f args) { std_out = CreatePipe }
System.Process.readProcess f args []
|
