summaryrefslogtreecommitdiff
path: root/Assistant/Threads/MountWatcher.hs
blob: c18bfb5bd6166df068175d8ee68961ab52b27c37 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
{- 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 Assistant.Common
import Assistant.DaemonStatus
import Assistant.Sync
import qualified Annex
import qualified Git
import Utility.ThreadScheduler
import Utility.Mounts
import Remote.List
import qualified Types.Remote as Remote

import qualified Data.Set as S

#if WITH_DBUS
import Utility.DBus
import DBus.Client
import DBus
import Data.Word (Word32)
import Control.Concurrent
import qualified Control.Exception as E
#else
#warning Building without dbus support; will use mtab polling
#endif

mountWatcherThread :: NamedThread
mountWatcherThread = namedThread "MountWatcher"
#if WITH_DBUS
	dbusThread
#else
	pollingThread
#endif

#if WITH_DBUS

dbusThread :: Assistant ()
dbusThread = do
	runclient <- asIO1 go
	r <- liftIO $ E.try $ runClient getSessionAddress runclient
	either onerr (const noop) r
  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 <- liftIO $ newMVar =<< currentMountPoints
			handleevent <- asIO1 $ \_event -> do
				nowmounted <- liftIO $ currentMountPoints
				wasmounted <- liftIO $ swapMVar mvar nowmounted
				handleMounts wasmounted nowmounted
			liftIO $ forM_ mountChanged $ \matcher ->
				listen client matcher handleevent
		, do
			liftAnnex $
				warning "No known volume monitor available through dbus; falling back to mtab polling"
			pollingThread
		)
	onerr :: E.SomeException -> Assistant ()
	onerr e = do
		{- If the session dbus fails, the user probably
		 - logged out of their desktop. Even if they log
		 - back in, we won't have access to the dbus
		 - session key, so polling is the best that can be
		 - done in this situation. -}
		liftAnnex $
			warning $ "dbus failed; falling back to mtab polling (" ++ show e ++ ")"
		pollingThread

{- Examine the list of services connected to dbus, to see if there
 - are any we can use to monitor mounts. If not, will attempt to start one. -}
checkMountMonitor :: Client -> Assistant Bool
checkMountMonitor client = do
	running <- filter (`elem` usableservices)
		<$> liftIO (listServiceNames client)
	case running of
		[] -> startOneService client startableservices
		(service:_) -> do
			debug [ "Using running DBUS service"
				, service
				, "to monitor mount events."
				]
			return True
  where
	startableservices = [gvfs, gvfsgdu]
	usableservices = startableservices ++ [kde]
	gvfs = "org.gtk.Private.UDisks2VolumeMonitor"
	gvfsgdu = "org.gtk.Private.GduVolumeMonitor"
	kde = "org.kde.DeviceNotifications"

startOneService :: Client -> [ServiceName] -> Assistant Bool
startOneService _ [] = return False
startOneService client (x:xs) = do
	_ <- liftIO $ tryNonAsync $ callDBus client "StartServiceByName"
		[toVariant x, toVariant (0 :: Word32)]
	ifM (liftIO $ elem x <$> listServiceNames client)
		( do
			debug
				[ "Started DBUS service", x
				, "to monitor mount events."
				]
			return True
		, startOneService client xs
		)

{- Filter matching events recieved when drives are mounted and unmounted. -}	
mountChanged :: [MatchRule]
mountChanged = [gvfs True, gvfs False, kde, kdefallback]
  where
	{- gvfs reliably generates this event whenever a
	 - drive is mounted/unmounted, whether automatically, or manually -}
	gvfs mount = matchAny
		{ matchInterface = Just "org.gtk.Private.RemoteVolumeMonitor"
		, matchMember = Just $ if mount then "MountAdded" else "MountRemoved"
		}
	{- This event fires when KDE prompts the user what to do with a drive,
	 - but maybe not at other times. And it's not received -}
	kde = matchAny
		{ matchInterface = Just "org.kde.Solid.Device"
		, matchMember = Just "setupDone"
		}
	{- This event may not be closely related to mounting a drive, but it's
	 - observed reliably when a drive gets mounted or unmounted. -}
	kdefallback = matchAny
		{ matchInterface = Just "org.kde.KDirNotify"
		, matchMember = Just "enteredDirectory"
		}

#endif

pollingThread :: Assistant ()
pollingThread = go =<< liftIO currentMountPoints
  where
	go wasmounted = do
		liftIO $ threadDelaySeconds (Seconds 10)
		nowmounted <- liftIO currentMountPoints
		handleMounts wasmounted nowmounted
		go nowmounted

handleMounts :: MountPoints -> MountPoints -> Assistant ()
handleMounts wasmounted nowmounted =
	mapM_ (handleMount . mnt_dir) $
		S.toList $ newMountPoints wasmounted nowmounted

handleMount :: FilePath -> Assistant ()
handleMount dir = do
	debug ["detected mount of", dir]
	rs <- filter (Git.repoIsLocal . Remote.repo) <$> remotesUnder dir
	reconnectRemotes True rs

{- Finds remotes located underneath the mount point.
 -
 - Updates state to include the remotes.
 -
 - The config of git remotes is re-read, as it may not have been available
 - at startup time, or may have changed (it could even be a different
 - repository at the same remote location..)
 -}
remotesUnder :: FilePath -> Assistant [Remote]
remotesUnder dir = do
	repotop <- liftAnnex $ fromRepo Git.repoPath
	rs <- liftAnnex remoteList
	pairs <- liftAnnex $ mapM (checkremote repotop) rs
	let (waschanged, rs') = unzip pairs
	when (or waschanged) $ do
		liftAnnex $ Annex.changeState $ \s -> s { Annex.remotes = catMaybes rs' }
		updateSyncRemotes
	return $ mapMaybe snd $ filter fst pairs
  where
	checkremote repotop r = case Remote.localpath r of
		Just p | dirContains dir (absPathFrom repotop p) ->
			(,) <$> pure True <*> updateRemote r
		_ -> return (False, Just r)

type MountPoints = S.Set Mntent

currentMountPoints :: IO MountPoints
currentMountPoints = S.fromList <$> getMounts

newMountPoints :: MountPoints -> MountPoints -> MountPoints
newMountPoints old new = S.difference new old