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|
{- git-annex assistant mount watcher, using either dbus or mtab polling
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}
module Assistant.Threads.MountWatcher where
import Common.Annex
import Assistant.ThreadedMonad
import Assistant.DaemonStatus
import Utility.ThreadScheduler
import Utility.Mounts
import Control.Concurrent
import qualified Control.Exception as E
import qualified Data.Set as S
#if WITH_DBUS
import DBus.Client
import DBus
import Data.Word (Word32)
#else
#warning Building without dbus support; will use mtab polling
#endif
mountWatcherThread :: ThreadState -> DaemonStatusHandle -> IO ()
mountWatcherThread st handle =
#if WITH_DBUS
dbusThread st handle
#else
pollingThread st handle
#endif
#if WITH_DBUS
dbusThread :: ThreadState -> DaemonStatusHandle -> IO ()
dbusThread st handle = E.catch (go =<< connectSession) onerr
where
go client = ifM (checkMountMonitor client)
( do
{- Store the current mount points in an mvar,
- to be compared later. We could in theory
- work out the mount point from the dbus
- message, but this is easier. -}
mvar <- newMVar =<< currentMountPoints
listen client mountAdded $ \_event -> do
nowmounted <- currentMountPoints
wasmounted <- swapMVar mvar nowmounted
handleMounts st handle wasmounted nowmounted
, do
runThreadState st $
warning "No known volume monitor available through dbus; falling back to mtab polling"
pollinstead
)
onerr :: E.SomeException -> IO ()
onerr e = do
runThreadState st $
warning $ "Failed to use dbus; falling back to mtab polling (" ++ show e ++ ")"
pollinstead
pollinstead = pollingThread st handle
listClientNames :: Client -> IO [String]
listClientNames client = do
reply <- callDBus client "ListNames" []
return $ fromMaybe [] $ fromVariant (methodReturnBody reply !! 0)
callDBus :: Client -> MemberName -> [Variant] -> IO MethodReturn
callDBus client name params = call_ client $
(methodCall "/org/freedesktop/DBus" "org.freedesktop.DBus" name)
{ methodCallDestination = Just "org.freedesktop.DBus"
, methodCallBody = params
}
{- Examine the list of clients connected to dbus, to see if there
- are any we can use to monitor mounts. If not, will attempt to start one. -}
checkMountMonitor :: Client -> IO Bool
checkMountMonitor client = ifM isrunning
( return True
, startclient knownclients
)
where
isrunning = any (`elem` knownclients) <$> listClientNames client
knownclients = ["org.gtk.Private.GduVolumeMonitor"]
startclient [] = return False
startclient (c:cs) = do
_ <- callDBus client "StartServiceByName"
[toVariant c, toVariant (0 :: Word32)]
ifM isrunning
( return True
, startclient cs
)
{- Filter matching events recieved when drives are mounted. -}
mountAdded ::MatchRule
mountAdded = matchAny
{ matchInterface = Just "org.gtk.Private.RemoteVolumeMonitor"
, matchMember = Just "MountAdded"
}
#endif
pollingThread :: ThreadState -> DaemonStatusHandle -> IO ()
pollingThread st handle = go =<< currentMountPoints
where
go wasmounted = do
threadDelaySeconds (Seconds 10)
nowmounted <- currentMountPoints
handleMounts st handle wasmounted nowmounted
go nowmounted
handleMounts :: ThreadState -> DaemonStatusHandle -> MountPoints -> MountPoints -> IO ()
handleMounts st handle wasmounted nowmounted = mapM_ (handleMount st handle) $
S.toList $ newMountPoints wasmounted nowmounted
handleMount :: ThreadState -> DaemonStatusHandle -> Mntent -> IO ()
handleMount st handle mntent = do
putStrLn $ "mounted: " ++ mnt_dir mntent
type MountPoints = S.Set Mntent
{- Reads mtab, getting the current set of mount points. -}
currentMountPoints :: IO MountPoints
currentMountPoints = S.fromList <$> getMounts
{- Finds new mount points, given an old and a new set. -}
newMountPoints :: MountPoints -> MountPoints -> MountPoints
newMountPoints old new = S.difference new old
|
