diff options
Diffstat (limited to 'src/Propellor/Engine.hs')
| -rw-r--r-- | src/Propellor/Engine.hs | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/src/Propellor/Engine.hs b/src/Propellor/Engine.hs index a3fc0f30..3fa9ffc0 100644 --- a/src/Propellor/Engine.hs +++ b/src/Propellor/Engine.hs @@ -8,11 +8,15 @@ import Data.Monoid import Control.Applicative import System.Console.ANSI import "mtl" Control.Monad.Reader +import Control.Exception (bracket) +import System.PosixCompat +import System.Posix.IO import Propellor.Types import Propellor.Message import Propellor.Exception import Propellor.Info +import Utility.Exception runPropellor :: Host -> Propellor a -> IO a runPropellor host a = runReaderT (runWithHost a) host @@ -47,3 +51,14 @@ fromHost l hn getter = case findHost l hn of Nothing -> return Nothing Just h -> liftIO $ Just <$> runReaderT (runWithHost getter) h + +onlyProcess :: FilePath -> IO a -> IO a +onlyProcess lockfile a = bracket lock unlock (const a) + where + lock = do + l <- createFile lockfile stdFileMode + setLock l (WriteLock, AbsoluteSeek, 0, 0) + `catchIO` const alreadyrunning + return l + unlock = closeFd + alreadyrunning = error "Propellor is already running on this host!" |