xmonad-config/lib/XMonad/Internal/Dependency.hs

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{-# LANGUAGE GADTs #-}
{-# LANGUAGE RecordWildCards #-}
--------------------------------------------------------------------------------
-- | Functions for handling dependencies
module XMonad.Internal.Dependency
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( MaybeAction
, MaybeX
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, DepTree(..)
, Action(..)
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, DBusDep(..)
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, FeatureX
, FeatureIO
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, Feature(..)
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, Warning(..)
, Dependency(..)
, UnitType(..)
, DBusMember(..)
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, ioFeature
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, evalFeature
, systemUnit
, userUnit
, pathR
, pathW
, pathRW
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, featureDefault
, featureExeArgs
, featureExe
, featureEndpoint
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, whenSatisfied
, ifSatisfied
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, executeFeature
, executeFeature_
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, executeFeatureWith
, executeFeatureWith_
) where
import Control.Monad.IO.Class
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import Control.Monad.Identity
import Data.List (find)
import Data.Maybe (catMaybes, fromMaybe, listToMaybe)
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import DBus
import DBus.Client
import DBus.Internal
import qualified DBus.Introspection as I
import System.Directory (findExecutable, readable, writable)
import System.Environment
import System.Exit
import XMonad.Core (X, io)
import XMonad.Internal.IO
import XMonad.Internal.Process
import XMonad.Internal.Shell
--------------------------------------------------------------------------------
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-- | Features
--
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-- A 'feature' is composed of a 'dependency tree' which at the root has an
-- 'action' to be performed with a number of 'dependencies' below it.
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--
-- NOTE: there is no way to make a feature depend on another feature. This is
-- very complicated to implement and would only be applicable to a few instances
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-- (notably the dbus interfaces). In order to implement a dependency tree, use
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-- dependencies that target the output/state of another feature; this is more
-- robust anyways, at the cost of being a bit slower.
data Feature a = Feature
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{ ftrDepTree :: DepTree a
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, ftrName :: String
, ftrWarning :: Warning
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}
| ConstFeature a
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-- TODO this is silly as is, and could be made more useful by representing
-- loglevels
data Warning = Silent | Default
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type FeatureX = Feature (X ())
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type FeatureIO = Feature (IO ())
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ioFeature :: MonadIO m => Feature (IO b) -> Feature (m b)
ioFeature (ConstFeature a) = ConstFeature $ liftIO a
ioFeature Feature {..} =
-- HACK just doing a normal record update here will make GHC complain about
-- an 'insufficiently polymorphic record update' ...I guess because my
-- GADT isn't polymorphic enough (which is obviously BS)
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Feature {ftrDepTree = liftIO <$> ftrDepTree, ..}
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featureDefault :: String -> [Dependency] -> a -> Feature a
featureDefault n ds x = Feature
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{ ftrDepTree = GenTree (Single x) ds
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, ftrName = n
, ftrWarning = Default
}
featureExe :: MonadIO m => String -> String -> Feature (m ())
featureExe n cmd = featureExeArgs n cmd []
featureExeArgs :: MonadIO m => String -> String -> [String] -> Feature (m ())
featureExeArgs n cmd args =
featureDefault n [Executable cmd] $ spawnCmd cmd args
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featureEndpoint :: String -> BusName -> ObjectPath -> InterfaceName -> MemberName
-> Maybe Client -> FeatureIO
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featureEndpoint name busname path iface mem client = Feature
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{ ftrDepTree = DBusTree (Single cmd) client deps []
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, ftrName = name
, ftrWarning = Default
}
where
cmd = \c -> void $ callMethod c busname path iface mem
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deps = [Endpoint busname path iface $ Method_ mem]
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--------------------------------------------------------------------------------
-- | Dependency Trees
--
-- Dependency trees have two subtypes: general and DBus. The latter require a
-- DBus client to evaluate (and will automatically fail if this is missing).
-- The former can be evaluated independently.
data DepTree a = GenTree (Action a) [Dependency]
| DBusTree (Action (Client -> a)) (Maybe Client) [DBusDep] [Dependency]
instance Functor DepTree where
fmap f (GenTree a ds) = GenTree (f <$> a) ds
fmap f (DBusTree a c es ds) = DBusTree (fmap (fmap f) a) c es ds
--------------------------------------------------------------------------------
-- | Actions
--
-- Actions have two subtypes: single and double. Single actions are just one
-- independent action. Double actions have one dependent pre-step which the
-- main action consumes (and fails if the pre-step fails).
data Action a = Single a | forall b. Double (b -> a) (IO (Either [String] b))
instance Functor Action where
fmap f (Single a) = Single (f a)
fmap f (Double a b) = Double (f . a) b
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--------------------------------------------------------------------------------
-- | Feature evaluation
--
-- Evaluate a feature by testing if its dependencies are satisfied, and return
-- either the action of the feature or 0 or more error messages that signify
-- what dependencies are missing and why.
type MaybeAction a = Maybe a
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type MaybeX = MaybeAction (X ())
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evalFeature :: Feature a -> IO (MaybeAction a)
evalFeature (ConstFeature x) = return $ Just x
evalFeature Feature
{ ftrDepTree = a
, ftrName = n
, ftrWarning = w
} = do
procName <- getProgName
res <- evalTree a
either (printWarnings procName) (return . Just) res
where
printWarnings procName es = do
case w of
Silent -> skip
Default -> let prefix = n ++ " disabled; "
es' = fmap (fmtMsg procName . (prefix ++)) es in
mapM_ putStrLn es'
return Nothing
fmtMsg procName msg = unwords [bracket procName, bracket "WARNING", msg]
bracket s = "[" ++ s ++ "]"
evalTree :: DepTree a -> IO (Either [String] a)
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evalTree (GenTree action ds) = do
es <- catMaybes <$> mapM evalDependency ds
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case es of
[] -> do
action' <- evalAction action
return $ case action' of
Right f -> Right f
Left es' -> Left es'
es' -> return $ Left es'
evalTree (DBusTree _ Nothing _ _) = return $ Left ["client not available"]
evalTree (DBusTree action (Just client) es ds) = do
eperrors <- mapM (dbusDepSatisfied client) es
dperrors <- mapM evalDependency ds
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case catMaybes (eperrors ++ dperrors) of
[] -> do
action' <- evalAction action
return $ case action' of
Right f -> Right $ f client
Left es' -> Left es'
es' -> return $ Left es'
evalAction :: Action a -> IO (Either [String] a)
evalAction (Single a) = return $ Right a
evalAction (Double a b) = fmap a <$> b
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executeFeatureWith :: MonadIO m => (m a -> m a) -> a -> Feature (IO a) -> m a
executeFeatureWith iof def ftr = do
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a <- io $ evalFeature ftr
maybe (return def) (iof . io) a
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executeFeatureWith_ :: MonadIO m => (m () -> m ()) -> Feature (IO ()) -> m ()
executeFeatureWith_ iof = executeFeatureWith iof ()
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executeFeature :: MonadIO m => a -> Feature (IO a) -> m a
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executeFeature = executeFeatureWith id
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executeFeature_ :: Feature (IO ()) -> IO ()
executeFeature_ = executeFeature ()
whenSatisfied :: Monad m => MaybeAction (m ()) -> m ()
whenSatisfied = flip ifSatisfied skip
ifSatisfied :: MaybeAction a -> a -> a
ifSatisfied (Just x) _ = x
ifSatisfied _ alt = alt
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--------------------------------------------------------------------------------
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-- | Dependencies (General)
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data Dependency = Executable String
| AccessiblePath FilePath Bool Bool
| IOTest (IO (Maybe String))
| Systemd UnitType String
data UnitType = SystemUnit | UserUnit deriving (Eq, Show)
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pathR :: String -> Dependency
pathR n = AccessiblePath n True False
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pathW :: String -> Dependency
pathW n = AccessiblePath n False True
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pathRW :: String -> Dependency
pathRW n = AccessiblePath n True True
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systemUnit :: String -> Dependency
systemUnit = Systemd SystemUnit
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userUnit :: String -> Dependency
userUnit = Systemd UserUnit
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--------------------------------------------------------------------------------
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-- | Dependencies (DBus)
data DBusMember = Method_ MemberName
| Signal_ MemberName
| Property_ String
deriving (Eq, Show)
data DBusDep =
Bus BusName
| Endpoint BusName ObjectPath InterfaceName DBusMember
deriving (Eq, Show)
--------------------------------------------------------------------------------
-- | Dependency evaluation (General)
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--
-- Test the existence of dependencies and return either Nothing (which actually
-- means success) or Just <error message>.
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evalDependency :: Dependency -> IO (Maybe String)
evalDependency (Executable n) = exeSatisfied n
evalDependency (IOTest t) = t
evalDependency (Systemd t n) = unitSatisfied t n
evalDependency (AccessiblePath p r w) = pathSatisfied p r w
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exeSatisfied :: String -> IO (Maybe String)
exeSatisfied x = do
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r <- findExecutable x
return $ case r of
(Just _) -> Nothing
_ -> Just $ "executable '" ++ x ++ "' not found"
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unitSatisfied :: UnitType -> String -> IO (Maybe String)
unitSatisfied u x = do
(rc, _, _) <- readCreateProcessWithExitCode' (shell cmd) ""
return $ case rc of
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ExitSuccess -> Nothing
_ -> Just $ "systemd " ++ unitType u ++ " unit '" ++ x ++ "' not found"
where
cmd = fmtCmd "systemctl" $ ["--user" | u == UserUnit] ++ ["status", x]
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unitType SystemUnit = "system"
unitType UserUnit = "user"
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pathSatisfied :: FilePath -> Bool -> Bool -> IO (Maybe String)
pathSatisfied p testread testwrite = do
res <- getPermissionsSafe p
let msg = permMsg res
return msg
where
testPerm False _ _ = Nothing
testPerm True f r = Just $ f r
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permMsg NotFoundError = Just "file not found"
permMsg PermError = Just "could not get permissions"
permMsg (PermResult r) =
case (testPerm testread readable r, testPerm testwrite writable r) of
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(Just False, Just False) -> Just "file not readable or writable"
(Just False, _) -> Just "file not readable"
(_, Just False) -> Just "file not writable"
_ -> Nothing
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--------------------------------------------------------------------------------
-- | Dependency evaluation (DBus)
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introspectInterface :: InterfaceName
introspectInterface = interfaceName_ "org.freedesktop.DBus.Introspectable"
introspectMethod :: MemberName
introspectMethod = memberName_ "Introspect"
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dbusDepSatisfied :: Client -> DBusDep -> IO (Maybe String)
dbusDepSatisfied client (Bus bus) = do
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ret <- callMethod client queryBus queryPath queryIface queryMem
return $ case ret of
Left e -> Just e
Right b -> let ns = bodyGetNames b in
if bus' `elem` ns then Nothing
else Just $ unwords ["name", singleQuote bus', "not found on dbus"]
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where
bus' = formatBusName bus
queryBus = busName_ "org.freedesktop.DBus"
queryIface = interfaceName_ "org.freedesktop.DBus"
queryPath = objectPath_ "/"
queryMem = memberName_ "ListNames"
bodyGetNames [v] = fromMaybe [] $ fromVariant v :: [String]
bodyGetNames _ = []
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dbusDepSatisfied client (Endpoint busname objpath iface mem) = do
ret <- callMethod client busname objpath introspectInterface introspectMethod
return $ case ret of
Left e -> Just e
Right body -> procBody body
where
procBody body = let res = findMem =<< I.parseXML objpath =<< fromVariant
=<< listToMaybe body in
case res of
Just True -> Nothing
_ -> Just $ fmtMsg' mem
findMem = fmap (matchMem mem)
. find (\i -> I.interfaceName i == iface)
. I.objectInterfaces
matchMem (Method_ n) = elemMember n I.methodName I.interfaceMethods
matchMem (Signal_ n) = elemMember n I.signalName I.interfaceSignals
matchMem (Property_ n) = elemMember n I.propertyName I.interfaceProperties
elemMember n fname fmember = elem n . fmap fname . fmember
fmtMem (Method_ n) = "method " ++ singleQuote (formatMemberName n)
fmtMem (Signal_ n) = "signal " ++ singleQuote (formatMemberName n)
fmtMem (Property_ n) = "property " ++ singleQuote n
fmtMsg' m = unwords
[ "could not find"
, fmtMem m
, "on interface"
, singleQuote $ formatInterfaceName iface
, "on bus"
, formatBusName busname
]