root / htools / Ganeti / Daemon.hs @ d575c755
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{-| Implementation of the generic daemon functionality. |
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-} |
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{- |
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Copyright (C) 2011, 2012 Google Inc. |
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, but |
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WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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02110-1301, USA. |
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-} |
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module Ganeti.Daemon |
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( DaemonOptions(..) |
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, OptType |
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, defaultOptions |
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, oShowHelp |
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, oShowVer |
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, oNoDaemonize |
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, oNoUserChecks |
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, oDebug |
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, oPort |
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, parseArgs |
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, writePidFile |
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, genericMain |
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) where |
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|
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import Control.Monad |
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import qualified Data.Version |
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import Data.Word |
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import System.Console.GetOpt |
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import System.Exit |
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import System.Environment |
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import System.Info |
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import System.IO |
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import System.Posix.Directory |
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import System.Posix.Files |
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import System.Posix.IO |
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import System.Posix.Process |
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import System.Posix.Types |
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import Text.Printf |
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|
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import Ganeti.Logging |
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import Ganeti.Runtime |
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import Ganeti.BasicTypes |
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import Ganeti.HTools.Utils |
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import qualified Ganeti.HTools.Version as Version(version) |
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import qualified Ganeti.Constants as C |
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|
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-- * Data types |
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|
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-- | Command line options structure. |
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data DaemonOptions = DaemonOptions |
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{ optShowHelp :: Bool -- ^ Just show the help |
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, optShowVer :: Bool -- ^ Just show the program version |
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, optDaemonize :: Bool -- ^ Whether to daemonize or not |
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, optPort :: Maybe Word16 -- ^ Override for the network port |
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, optDebug :: Bool -- ^ Enable debug messages |
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, optNoUserChecks :: Bool -- ^ Ignore user checks |
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} |
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-- | Default values for the command line options. |
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defaultOptions :: DaemonOptions |
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defaultOptions = DaemonOptions |
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{ optShowHelp = False |
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, optShowVer = False |
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, optDaemonize = True |
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, optPort = Nothing |
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, optDebug = False |
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, optNoUserChecks = False |
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} |
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-- | Abrreviation for the option type. |
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type OptType = OptDescr (DaemonOptions -> Result DaemonOptions) |
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|
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-- | Helper function for required arguments which need to be converted |
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-- as opposed to stored just as string. |
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reqWithConversion :: (String -> Result a) |
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-> (a -> DaemonOptions -> Result DaemonOptions) |
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-> String |
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-> ArgDescr (DaemonOptions -> Result DaemonOptions) |
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reqWithConversion conversion_fn updater_fn metavar = |
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ReqArg (\string_opt opts -> do |
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parsed_value <- conversion_fn string_opt |
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updater_fn parsed_value opts) metavar |
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|
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-- * Command line options |
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oShowHelp :: OptType |
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oShowHelp = Option "h" ["help"] |
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(NoArg (\ opts -> Ok opts { optShowHelp = True})) |
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"Show the help message and exit" |
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oShowVer :: OptType |
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oShowVer = Option "V" ["version"] |
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(NoArg (\ opts -> Ok opts { optShowVer = True})) |
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"Show the version of the program and exit" |
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oNoDaemonize :: OptType |
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oNoDaemonize = Option "f" ["foreground"] |
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(NoArg (\ opts -> Ok opts { optDaemonize = False})) |
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"Don't detach from the current terminal" |
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oDebug :: OptType |
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oDebug = Option "d" ["debug"] |
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(NoArg (\ opts -> Ok opts { optDebug = True })) |
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"Enable debug messages" |
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|
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oNoUserChecks :: OptType |
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oNoUserChecks = Option "" ["no-user-checks"] |
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(NoArg (\ opts -> Ok opts { optNoUserChecks = True })) |
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"Ignore user checks" |
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oPort :: Int -> OptType |
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oPort def = Option "p" ["--port"] |
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(reqWithConversion (tryRead "reading port") |
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(\port opts -> Ok opts { optPort = Just port }) "PORT") |
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("Network port (default: " ++ show def ++ ")") |
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-- | Usage info. |
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usageHelp :: String -> [OptType] -> String |
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usageHelp progname = |
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usageInfo (printf "%s %s\nUsage: %s [OPTION...]" |
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progname Version.version progname) |
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-- | Command line parser, using the 'Options' structure. |
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parseOpts :: [String] -- ^ The command line arguments |
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-> String -- ^ The program name |
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-> [OptType] -- ^ The supported command line options |
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-> IO (DaemonOptions, [String]) -- ^ The resulting options |
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-- and leftover arguments |
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parseOpts argv progname options = |
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case getOpt Permute options argv of |
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(opt_list, args, []) -> |
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do |
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parsed_opts <- |
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case foldM (flip id) defaultOptions opt_list of |
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Bad msg -> do |
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hPutStrLn stderr "Error while parsing command\ |
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\line arguments:" |
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hPutStrLn stderr msg |
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exitWith $ ExitFailure 1 |
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Ok val -> return val |
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return (parsed_opts, args) |
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(_, _, errs) -> do |
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hPutStrLn stderr $ "Command line error: " ++ concat errs |
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hPutStrLn stderr $ usageHelp progname options |
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exitWith $ ExitFailure 2 |
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-- | Small wrapper over getArgs and 'parseOpts'. |
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parseArgs :: String -> [OptType] -> IO (DaemonOptions, [String]) |
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parseArgs cmd options = do |
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cmd_args <- getArgs |
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parseOpts cmd_args cmd options |
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-- * Daemon-related functions |
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-- | PID file mode. |
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pidFileMode :: FileMode |
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pidFileMode = unionFileModes ownerReadMode ownerWriteMode |
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-- | Writes a PID file and locks it. |
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_writePidFile :: FilePath -> IO Fd |
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_writePidFile path = do |
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fd <- createFile path pidFileMode |
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setLock fd (WriteLock, AbsoluteSeek, 0, 0) |
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my_pid <- getProcessID |
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_ <- fdWrite fd (show my_pid ++ "\n") |
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return fd |
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-- | Wrapper over '_writePidFile' that transforms IO exceptions into a |
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-- 'Bad' value. |
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writePidFile :: FilePath -> IO (Result Fd) |
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writePidFile path = do |
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catch (fmap Ok $ _writePidFile path) (return . Bad . show) |
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-- | Sets up a daemon's environment. |
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setupDaemonEnv :: FilePath -> FileMode -> IO () |
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setupDaemonEnv cwd umask = do |
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changeWorkingDirectory cwd |
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_ <- setFileCreationMask umask |
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_ <- createSession |
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return () |
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-- | Run an I/O action as a daemon. |
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-- |
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-- WARNING: this only works in single-threaded mode (either using the |
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-- single-threaded runtime, or using the multi-threaded one but with |
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-- only one OS thread, i.e. -N1). |
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-- |
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-- FIXME: this doesn't support error reporting and the prepfn |
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-- functionality. |
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daemonize :: IO () -> IO () |
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daemonize action = do |
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-- first fork |
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_ <- forkProcess $ do |
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-- in the child |
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setupDaemonEnv "/" (unionFileModes groupModes otherModes) |
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_ <- forkProcess action |
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exitImmediately ExitSuccess |
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exitImmediately ExitSuccess |
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-- | Generic daemon startup. |
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genericMain :: GanetiDaemon -> [OptType] -> (DaemonOptions -> IO ()) -> IO () |
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genericMain daemon options main = do |
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let progname = daemonName daemon |
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(opts, args) <- parseArgs progname options |
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when (optShowHelp opts) $ do |
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putStr $ usageHelp progname options |
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exitWith ExitSuccess |
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when (optShowVer opts) $ do |
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printf "%s %s\ncompiled with %s %s\nrunning on %s %s\n" |
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progname Version.version |
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compilerName (Data.Version.showVersion compilerVersion) |
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os arch :: IO () |
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exitWith ExitSuccess |
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unless (null args) $ do |
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hPutStrLn stderr "This program doesn't take any arguments" |
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exitWith $ ExitFailure C.exitFailure |
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unless (optNoUserChecks opts) $ do |
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runtimeEnts <- getEnts |
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case runtimeEnts of |
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Bad msg -> do |
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hPutStrLn stderr $ "Can't find required user/groups: " ++ msg |
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exitWith $ ExitFailure C.exitFailure |
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Ok ents -> verifyDaemonUser daemon ents |
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let processFn = if optDaemonize opts then daemonize else id |
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processFn $ innerMain daemon opts (main opts) |
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-- | Inner daemon function. |
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-- |
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-- This is executed after daemonization. |
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innerMain :: GanetiDaemon -> DaemonOptions -> IO () -> IO () |
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innerMain daemon opts main = do |
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setupLogging (daemonLogFile daemon) (daemonName daemon) (optDebug opts) |
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(not (optDaemonize opts)) False |
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pid_fd <- writePidFile (daemonPidFile daemon) |
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case pid_fd of |
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Bad msg -> do |
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hPutStrLn stderr $ "Cannot write PID file; already locked? Error: " ++ |
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msg |
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exitWith $ ExitFailure 1 |
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_ -> return () |
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logNotice "starting" |
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main |