-- | -- Module : Streamly.Internal.FileSystem.Event.Linux -- Copyright : (c) 2020 Composewell Technologies -- License : BSD-3-Clause -- Maintainer : streamly@composewell.com -- Stability : pre-release -- Portability : GHC -- -- =Overview -- -- Use 'watchPaths' with a list of file system paths you want to watch as -- argument. It returns a stream of 'Event' representing the file system events -- occurring under the watched paths. -- -- @ -- Stream.mapM_ (putStrLn . 'showEvent') $ 'watchPaths' [Array.fromCString\# "dir"#] -- @ -- -- 'Event' is an opaque type. Accessor functions (e.g. 'showEvent' above) -- provided in this module are used to determine the attributes of the event. -- -- Identical successive events may be coalesced into a single event. -- -- =Design notes -- -- For reference documentation see: -- -- * -- -- We try to keep the macOS\/Linux/Windows event handling APIs and defaults -- semantically and syntactically as close as possible. -- -- =BUGs -- -- When testing on Linux Kernel version @5.3.0-53-generic #47-Ubuntu@, the last -- event for the root path seems to be delayed until one more event occurs. -- -- = Differences between macOS and Linux APIs: -- -- 1. macOS watch is based on the path provided to it, if the path is -- deleted and recreated it will still be watched, if the path moves to another -- path it won't be watched anymore. Whereas Linux watch is based on a handle -- to the path, if the path is deleted and recreated it won't be watched, if -- the path moves to another it can still be watched (though this is -- configurable). -- -- 2. macOS watches the directory hierarchy recursively, Linux watches only one -- level of dir, recursive watch has to be built in user space by watching for -- create events and adding the new directories to the watch. Not sure how this -- will scale for too many paths. -- -- 3. In macOS the path of the subject of the event is absolute, in Linux the -- path is the name of the object inside the dir being watched. -- -- 4. On Linux 'watchPaths' fails if a path does not exist, on macOS it does -- not fail. #include "config.h" #if HAVE_DECL_IN_EXCL_UNLINK module Streamly.Internal.FileSystem.Event.Linux ( -- * Subscribing to events -- ** Default configuration Config , Toggle (..) , defaultConfig -- ** Watch Behavior , setFollowSymLinks , setUnwatchMoved , setOneShot , setOnlyDir , WhenExists (..) , setWhenExists -- ** Events of Interest -- *** Root Level Events , setRootDeleted , setRootMoved -- *** Item Level Metadata change , setMetadataChanged -- *** Item Level Access , setAccessed , setOpened , setWriteClosed , setNonWriteClosed -- *** Item CRUD events , setCreated , setDeleted , setMovedFrom , setMovedTo , setModified , setAllEvents -- ** Watch APIs -- XXX watchPaths is redundant now because we can use watchTrees with -- setRecursiveMode False. Perhaps we can use a common "watch" API. , watchPathsWith , watchPaths , watchTreesWith , watchTrees , addToWatch , removeFromWatch -- * Handling Events , Event(..) , getRoot , getRelPath , getAbsPath , getCookie -- ** Exception Conditions , isOverflow -- ** Root Level Events , isRootUnwatched , isRootDeleted , isRootMoved , isRootUnmounted -- ** Item Level Metadata change , isMetadataChanged -- ** Item Level Access , isAccessed , isOpened , isWriteClosed , isNonWriteClosed -- ** Item CRUD events , isCreated , isDeleted , isMovedFrom , isMovedTo , isModified -- ** Item Path info , isDir -- * Debugging , showEvent ) where import Control.Monad (void, when) import Control.Monad.IO.Class (MonadIO, liftIO) import Data.Bits ((.|.), (.&.), complement) import Data.Char (ord) import Data.Foldable (foldlM) import Data.Functor.Identity (runIdentity) import Data.IntMap.Lazy (IntMap) import Data.IORef (IORef, newIORef, readIORef, writeIORef, modifyIORef) import Data.List.NonEmpty (NonEmpty) #if !(MIN_VERSION_base(4,11,0)) import Data.Semigroup (Semigroup(..)) #endif import Data.Word (Word8, Word32) import Foreign.C.Error (throwErrnoIfMinus1) import Foreign.C.String (CString) import Foreign.C.Types (CInt(..), CUInt(..)) import Foreign.Ptr (Ptr) import Foreign.Storable (peek, peekByteOff, sizeOf) import GHC.IO.Device (IODeviceType(Stream)) import GHC.IO.FD (fdFD, mkFD) import GHC.IO.Handle.FD (mkHandleFromFD) import Streamly.Prelude (SerialT) import Streamly.Internal.Data.Parser (Parser) import Streamly.Internal.Data.Array.Foreign.Type (Array(..)) import System.IO (Handle, hClose, IOMode(ReadMode)) #if !MIN_VERSION_base(4,10,0) import Control.Concurrent.MVar (readMVar) import Data.Typeable (cast) import GHC.IO.Exception (IOException(..), IOErrorType(..), ioException) import GHC.IO.FD (FD) import GHC.IO.Handle.Types (Handle__(..), Handle(FileHandle, DuplexHandle)) #else import GHC.IO.Handle.FD (handleToFd) #endif import qualified Data.IntMap.Lazy as Map import qualified Data.List.NonEmpty as NonEmpty import qualified Streamly.Internal.Data.Array.Foreign as A import qualified Streamly.Internal.Data.Fold as FL import qualified Streamly.Internal.Data.Parser as PR import qualified Streamly.Internal.Data.Stream.IsStream as S import qualified Streamly.Internal.FileSystem.Dir as Dir import qualified Streamly.Internal.FileSystem.Handle as FH import qualified Streamly.Internal.Unicode.Stream as U ------------------------------------------------------------------------------- -- Subscription to events ------------------------------------------------------------------------------- -- | Watch configuration, used to specify the events of interest and the -- behavior of the watch. -- -- /Pre-release/ -- data Config = Config { watchRec :: Bool , createFlags :: Word32 } ------------------------------------------------------------------------------- -- Boolean settings ------------------------------------------------------------------------------- -- | Whether a setting is 'On' or 'Off'. -- -- /Pre-release/ -- data Toggle = On | Off toggle :: Toggle -> Toggle toggle On = Off toggle Off = On setFlag :: Word32 -> Toggle -> Config -> Config setFlag mask status cfg@Config{..} = let flags = case status of On -> createFlags .|. mask Off -> createFlags .&. complement mask in cfg {createFlags = flags} ------------------------------------------------------------------------------- -- Settings ------------------------------------------------------------------------------- -- | Watch the whole directory tree recursively instead of watching just one -- level of directory. -- -- /default: Off/ -- -- /Pre-release/ -- setRecursiveMode :: Bool -> Config -> Config setRecursiveMode rec cfg@Config{} = cfg {watchRec = rec} foreign import capi "sys/inotify.h value IN_DONT_FOLLOW" iN_DONT_FOLLOW :: Word32 -- | If the pathname to be watched is a symbolic link then watch the target of -- the symbolic link instead of the symbolic link itself. -- -- /default: On/ -- -- /Pre-release/ -- setFollowSymLinks :: Toggle -> Config -> Config setFollowSymLinks s = setFlag iN_DONT_FOLLOW (toggle s) foreign import capi "sys/inotify.h value IN_EXCL_UNLINK" iN_EXCL_UNLINK :: Word32 -- | If an object moves out of the directory being watched then stop watching -- it. -- -- /default: On/ -- -- /Pre-release/ -- setUnwatchMoved :: Toggle -> Config -> Config setUnwatchMoved = setFlag iN_EXCL_UNLINK #if HAVE_DECL_IN_MASK_CREATE foreign import capi "sys/inotify.h value IN_MASK_CREATE" iN_MASK_CREATE :: Word32 #endif foreign import capi "sys/inotify.h value IN_MASK_ADD" iN_MASK_ADD :: Word32 -- | What to do if a watch already exists when 'openWatch' or 'addToWatch' is -- called for a path. -- -- /Pre-release/ -- data WhenExists = AddIfExists -- ^ Do not set an existing setting to 'Off' only set to 'On' | ReplaceIfExists -- ^ Replace the existing settings with new settings #if HAVE_DECL_IN_MASK_CREATE | FailIfExists -- ^ Fail the API #endif -- | When adding a new path to the watch, specify what to do if a watch already -- exists on that path. -- -- /default: FailIfExists/ -- -- /Pre-release/ -- setWhenExists :: WhenExists -> Config -> Config setWhenExists val cfg = case val of AddIfExists -> setFlag iN_MASK_ADD On cfg ReplaceIfExists -> setFlag iN_MASK_ADD Off cfg #if HAVE_DECL_IN_MASK_CREATE FailIfExists -> setFlag iN_MASK_CREATE On cfg #endif foreign import capi "sys/inotify.h value IN_ONESHOT" iN_ONESHOT :: Word32 -- | Watch the object only for one event and then remove it from the watch. -- -- /default: Off/ -- -- /Pre-release/ -- setOneShot :: Toggle -> Config -> Config setOneShot = setFlag iN_ONESHOT foreign import capi "sys/inotify.h value IN_ONLYDIR" iN_ONLYDIR :: Word32 -- | Watch the object only if it is a directory. This provides a race-free way -- to ensure that the watched object is a directory. -- -- /default: Off/ -- -- /Pre-release/ -- setOnlyDir :: Toggle -> Config -> Config setOnlyDir = setFlag iN_ONLYDIR ------------------------------------------------------------------------------- -- Event types that can occur ------------------------------------------------------------------------------- foreign import capi "sys/inotify.h value IN_DELETE_SELF" iN_DELETE_SELF :: Word32 -- | Report when the watched path itself gets deleted. -- -- /default: On/ -- -- /Pre-release/ -- setRootDeleted :: Toggle -> Config -> Config setRootDeleted = setFlag iN_DELETE_SELF foreign import capi "sys/inotify.h value IN_MOVE_SELF" iN_MOVE_SELF :: Word32 -- | Report when the watched root path itself gets renamed. -- -- /default: On/ -- -- /Pre-release/ -- setRootMoved :: Toggle -> Config -> Config setRootMoved = setFlag iN_MOVE_SELF foreign import capi "sys/inotify.h value IN_ATTRIB" iN_ATTRIB :: Word32 -- | Report when the metadata e.g. owner, permission modes, modifications times -- of an object changes. -- -- /default: On/ -- -- /Pre-release/ -- setMetadataChanged :: Toggle -> Config -> Config setMetadataChanged = setFlag iN_ATTRIB foreign import capi "sys/inotify.h value IN_ACCESS" iN_ACCESS :: Word32 -- | Report when a file is accessed. -- -- /default: On/ -- -- /Pre-release/ -- setAccessed :: Toggle -> Config -> Config setAccessed = setFlag iN_ACCESS foreign import capi "sys/inotify.h value IN_OPEN" iN_OPEN :: Word32 -- | Report when a file is opened. -- -- /default: On/ -- -- /Pre-release/ -- setOpened :: Toggle -> Config -> Config setOpened = setFlag iN_OPEN foreign import capi "sys/inotify.h value IN_CLOSE_WRITE" iN_CLOSE_WRITE :: Word32 -- | Report when a file that was opened for writes is closed. -- -- /default: On/ -- -- /Pre-release/ -- setWriteClosed :: Toggle -> Config -> Config setWriteClosed = setFlag iN_CLOSE_WRITE foreign import capi "sys/inotify.h value IN_CLOSE_NOWRITE" iN_CLOSE_NOWRITE :: Word32 -- | Report when a file that was opened for not writing is closed. -- -- /default: On/ -- -- /Pre-release/ -- setNonWriteClosed :: Toggle -> Config -> Config setNonWriteClosed = setFlag iN_CLOSE_NOWRITE foreign import capi "sys/inotify.h value IN_CREATE" iN_CREATE :: Word32 -- | Report when a file is created. -- -- /default: On/ -- -- /Pre-release/ -- setCreated :: Toggle -> Config -> Config setCreated = setFlag iN_CREATE foreign import capi "sys/inotify.h value IN_DELETE" iN_DELETE :: Word32 -- | Report when a file is deleted. -- -- /default: On/ -- -- /Pre-release/ -- setDeleted :: Toggle -> Config -> Config setDeleted = setFlag iN_DELETE foreign import capi "sys/inotify.h value IN_MOVED_FROM" iN_MOVED_FROM :: Word32 -- | Report the source of a move. -- -- /default: On/ -- -- /Pre-release/ -- setMovedFrom :: Toggle -> Config -> Config setMovedFrom = setFlag iN_MOVED_FROM foreign import capi "sys/inotify.h value IN_MOVED_TO" iN_MOVED_TO :: Word32 -- | Report the target of a move. -- -- /default: On/ -- -- /Pre-release/ -- setMovedTo :: Toggle -> Config -> Config setMovedTo = setFlag iN_MOVED_TO foreign import capi "sys/inotify.h value IN_MODIFY" iN_MODIFY :: Word32 -- | Report when a file is modified. -- -- /default: On/ -- -- /Pre-release/ -- setModified :: Toggle -> Config -> Config setModified = setFlag iN_MODIFY -- | Set all events 'On' or 'Off'. -- -- /default: On/ -- -- /Pre-release/ -- setAllEvents :: Toggle -> Config -> Config setAllEvents s cfg = ( setRootDeleted s . setRootMoved s . setMetadataChanged s . setAccessed s . setOpened s . setWriteClosed s . setNonWriteClosed s . setCreated s . setDeleted s . setMovedFrom s . setMovedTo s . setModified s ) cfg ------------------------------------------------------------------------------- -- Default config ------------------------------------------------------------------------------- -- The defaults are set in such a way that the behavior on macOS and Linux is -- as much compatible as possible. -- -- | The default is: -- -- * 'setFollowSymLinks' 'On' -- * 'setUnwatchMoved' 'On' -- * 'setOneShot' 'Off' -- * 'setOnlyDir' 'Off' -- * 'setWhenExists' 'AddIfExists' -- * 'setAllEvents' 'On' -- -- /Pre-release/ -- defaultConfig :: Config defaultConfig = setWhenExists AddIfExists $ setAllEvents On $ Config { watchRec = True , createFlags = 0 } ------------------------------------------------------------------------------- -- Open an event stream ------------------------------------------------------------------------------- -- | A handle for a watch. data Watch = Watch Handle -- File handle for the watch (IORef (IntMap -- Key is the watch descriptor ( Array Word8 -- Absolute path of the watch root , Array Word8 -- Path of subdir relative to watch root ) ) ) -- Instead of using the watch descriptor we can provide APIs that use the path -- itself to identify the watch. That will require us to maintain a map from wd -- to path in the Watch handle. newtype WD = WD CInt deriving Show foreign import ccall unsafe "sys/inotify.h inotify_init" c_inotify_init :: IO CInt -- | Create a 'Watch' handle. 'addToWatch' can be used to add paths being -- monitored by this watch. -- -- /Pre-release/ -- createWatch :: IO Watch createWatch = do rawfd <- throwErrnoIfMinus1 "createWatch" c_inotify_init -- we could use fdToHandle but it cannot determine the fd type -- automatically for the inotify fd (fd, fdType) <- mkFD rawfd ReadMode (Just (Stream, 0, 0)) -- (IODeviceType, CDev, CIno) False -- not a socket False -- non-blocking is false let fdString = "" h <- mkHandleFromFD fd fdType fdString ReadMode True -- use non-blocking IO Nothing -- TextEncoding (binary) emptyMapRef <- newIORef Map.empty return $ Watch h emptyMapRef foreign import ccall unsafe "sys/inotify.h inotify_add_watch" c_inotify_add_watch :: CInt -> CString -> CUInt -> IO CInt -- XXX we really do not know the path encoding, all we know is that it is "/" -- separated bytes. So these may fail or convert the path in an unexpected -- manner. We should ultimately remove all usage of these. toUtf8 :: MonadIO m => String -> m (Array Word8) toUtf8 = A.fromStream . U.encodeUtf8 . S.fromList utf8ToString :: Array Word8 -> String utf8ToString = runIdentity . S.toList . U.decodeUtf8' . A.toStream #if !MIN_VERSION_base(4,10,0) -- | Turn an existing Handle into a file descriptor. This function throws an -- IOError if the Handle does not reference a file descriptor. handleToFd :: Handle -> IO FD handleToFd h = case h of FileHandle _ mv -> do Handle__{haDevice = dev} <- readMVar mv case cast dev of Just fd -> return fd Nothing -> throwErr "not a file descriptor" DuplexHandle{} -> throwErr "not a file handle" where throwErr msg = ioException $ IOError (Just h) InappropriateType "handleToFd" msg Nothing Nothing #endif -- | Add a trailing "/" at the end of the path if there is none. Do not add a -- "/" if the path is empty. -- ensureTrailingSlash :: Array Word8 -> Array Word8 ensureTrailingSlash path = if A.length path /= 0 then let mx = A.getIndex path (A.length path - 1) in case mx of Nothing -> error "ensureTrailingSlash: Bug: Invalid index" Just x -> if x /= fromIntegral (ord '/') then path <> A.fromCString# "/"# else path else path -- | @addToWatch cfg watch root subpath@ adds @subpath@ to the list of paths -- being monitored under @root@ via the watch handle @watch@. @root@ must be -- an absolute path and @subpath@ must be relative to @root@. -- -- /Pre-release/ -- addToWatch :: Config -> Watch -> Array Word8 -> Array Word8 -> IO () addToWatch cfg@Config{..} watch@(Watch handle wdMap) root0 path0 = do -- XXX do not add if the path is already added -- XXX if the watch is added by the scan and not via an event we can -- generate a create event assuming that the create may have been lost. We -- can also mark in the map that this entry was added by the scan. So if an -- actual create event later comes and tries to add this again then we can -- ignore that and drop the create event to avoid duplicate create, because -- we have already emitted it. -- -- When a directory is added by the scan we should also emit create events -- for files that may have got added to the dir. However, such create -- events may get duplicated because of a race between the scan generated -- versus real events. -- -- Or we may distinguish between scan generated events and real events so -- that the application can assume that other events may been lost and -- handle it. For example, if it is a dir create the application can read -- the dir to scan the files in it. -- let root = ensureTrailingSlash root0 path = ensureTrailingSlash path0 absPath = root <> path fd <- handleToFd handle -- XXX we need to tolerate an error where we are adding a watch for a -- non-existing file because the file may have got deleted by the time we -- added the watch. Perhaps we can have a flag in config for this and keep -- the default value to tolerate the error. -- -- XXX The file may have even got deleted and then recreated which we will -- never get to know, document this. wd <- A.unsafeAsCString absPath $ \pathPtr -> throwErrnoIfMinus1 ("addToWatch: " ++ utf8ToString absPath) $ c_inotify_add_watch (fdFD fd) pathPtr (CUInt createFlags) -- We add the parent first so that we start getting events for any new -- creates and add the new subdirectories on creates while we are adding -- the children. modifyIORef wdMap (Map.insert (fromIntegral wd) (root, path)) -- Now add the children. If we missed any creates while we were adding the -- parent, this will make sure they are added too. -- -- XXX Ensure that we generate events that we may have missed while we were -- adding the dirs. -- -- XXX toDirs currently uses paths as String, we need to convert it -- to "/" separated by byte arrays. when watchRec $ do S.mapM_ (\p -> addToWatch cfg watch root (path <> p)) $ S.mapM toUtf8 $ Dir.toDirs $ utf8ToString absPath foreign import ccall unsafe "sys/inotify.h inotify_rm_watch" c_inotify_rm_watch :: CInt -> CInt -> IO CInt -- | Remove an absolute root path from a 'Watch', if a path was moved after -- adding you need to provide the original path which was used to add the -- Watch. -- -- /Pre-release/ -- removeFromWatch :: Watch -> Array Word8 -> IO () removeFromWatch (Watch handle wdMap) path = do fd <- handleToFd handle km <- readIORef wdMap wdMap1 <- foldlM (step fd) Map.empty (Map.toList km) writeIORef wdMap wdMap1 where step fd newMap (wd, v) = do if (fst v) == path then do let err = "removeFromWatch: " ++ show (utf8ToString path) rm = c_inotify_rm_watch (fdFD fd) (fromIntegral wd) void $ throwErrnoIfMinus1 err rm return newMap else return $ Map.insert wd v newMap -- | Given a 'Config' and list of @paths@ ("/" separated byte arrays) start -- monitoring the paths for file system events. Returns a 'Watch' handle which -- can then be used to read the event stream or to close the watch. -- -- /Pre-release/ -- openWatch :: Config -> NonEmpty (Array Word8) -> IO Watch openWatch cfg paths = do w <- createWatch mapM_ (\p -> addToWatch cfg w p (A.fromList [])) $ NonEmpty.toList paths return w -- | Close a 'Watch' handle. -- -- /Pre-release/ -- closeWatch :: Watch -> IO () closeWatch (Watch h _) = hClose h ------------------------------------------------------------------------------- -- Raw events read from the watch file handle ------------------------------------------------------------------------------- newtype Cookie = Cookie Word32 deriving (Show, Eq) -- | An Event generated by the file system. Use the accessor functions to -- examine the event. -- -- /Pre-release/ -- data Event = Event { eventWd :: CInt , eventFlags :: Word32 , eventCookie :: Word32 , eventRelPath :: Array Word8 , eventMap :: IntMap (Array Word8, Array Word8) } deriving (Show, Ord, Eq) -- The inotify event struct from the man page/header file: -- -- struct inotify_event { -- int wd; /* Watch descriptor */ -- uint32_t mask; /* Mask describing event */ -- uint32_t cookie; /* Unique cookie associating related -- events (for rename(2)) */ -- uint32_t len; /* Size of name field */ -- char name[]; /* Optional null-terminated name */ -- }; -- -- XXX We can perhaps use parseD monad instance for fusing with parseMany? Need -- to measure the perf. -- readOneEvent :: Config -> Watch -> Parser IO Word8 Event readOneEvent cfg wt@(Watch _ wdMap) = do let headerLen = (sizeOf (undefined :: CInt)) + 12 arr <- PR.takeEQ headerLen (A.writeN headerLen) (ewd, eflags, cookie, pathLen) <- PR.fromEffect $ A.unsafeAsPtr arr readHeader -- XXX need the "initial" in parsers to return a step type so that "take 0" -- can return without an input. otherwise if pathLen is 0 we will keep -- waiting to read one more char before we return this event. path <- if pathLen /= 0 then do -- XXX takeEndBy_ drops the separator so assumes a null -- terminated path, we should use a takeWhile nested inside a -- takeP pth <- PR.fromFold $ FL.takeEndBy_ (== 0) $ FL.take pathLen (A.writeN pathLen) let remaining = pathLen - A.length pth - 1 when (remaining /= 0) $ PR.takeEQ remaining FL.drain return pth else return $ A.fromList [] wdm <- PR.fromEffect $ readIORef wdMap let (root, sub) = case Map.lookup (fromIntegral ewd) wdm of Just pair -> pair Nothing -> error $ "readOneEvent: " <> "Unknown watch descriptor: " <> show ewd let -- "sub" is guaranteed to have a trailing "/" sub1 = sub <> path -- Check for "ISDIR" first because it is less likely isDirCreate = eflags .&. iN_ISDIR /= 0 && eflags .&. iN_CREATE /= 0 when (watchRec cfg && isDirCreate) $ PR.fromEffect $ addToWatch cfg wt root sub1 -- XXX Handle IN_DELETE, IN_DELETE_SELF, IN_MOVE_SELF, IN_MOVED_FROM, -- IN_MOVED_TO -- What if a large dir tree gets moved in to our hierarchy? Do we get a -- single event for the top level dir in this case? return $ Event { eventWd = (fromIntegral ewd) , eventFlags = eflags , eventCookie = cookie , eventRelPath = sub1 , eventMap = wdm } where readHeader (ptr :: Ptr Word8) = do let len = sizeOf (undefined :: CInt) ewd <- peek ptr eflags <- peekByteOff ptr len cookie <- peekByteOff ptr (len + 4) pathLen :: Word32 <- peekByteOff ptr (len + 8) return (ewd, eflags, cookie, fromIntegral pathLen) watchToStream :: Config -> Watch -> SerialT IO Event watchToStream cfg wt@(Watch handle _) = do -- Do not use too small a buffer. As per inotify man page: -- -- The behavior when the buffer given to read(2) is too small to return -- information about the next event depends on the kernel version: in -- kernels before 2.6.21, read(2) returns 0; since kernel 2.6.21, read(2) -- fails with the error EINVAL. Specifying a buffer of size -- -- sizeof(struct inotify_event) + NAME_MAX + 1 -- -- will be sufficient to read at least one event. S.parseMany (readOneEvent cfg wt) $ S.unfold FH.read handle -- | Start monitoring a list of file system paths for file system events with -- the supplied configuration operation over the 'defaultConfig'. The -- paths could be files or directories. When the path is a directory, only the -- files and directories directly under the watched directory are monitored, -- contents of subdirectories are not monitored. Monitoring starts from the -- current time onwards. The paths are specified as "/" separated 'Array' of -- 'Word8'. -- -- @ -- watchPathsWith -- ('setFollowSymLinks' On . 'setUnwatchMoved' Off) -- [Array.fromCString\# "dir"#] -- @ -- -- /Pre-release/ -- watchPathsWith :: (Config -> Config) -> NonEmpty (Array Word8) -> SerialT IO Event watchPathsWith f = watchTreesWith (f . setRecursiveMode False) -- | Like 'watchPathsWith' but uses the 'defaultConfig' options. -- -- @ -- watchPaths = watchPathsWith id -- @ -- -- /Pre-release/ -- watchPaths :: NonEmpty (Array Word8) -> SerialT IO Event watchPaths = watchPathsWith id -- XXX We should not go across the mount points of network file systems or file -- systems that are known to not generate any events. -- -- | Start monitoring a list of file system paths for file system events with -- the supplied configuration operation over the 'defaultConfig'. The -- paths could be files or directories. When the path is a directory, the -- whole directory tree under it is watched recursively. Monitoring starts from -- the current time onwards. -- -- Note that recrusive watch on a large directory tree could be expensive. When -- starting a watch, the whole tree must be read and watches are started on -- each directory in the tree. The initial time to start the watch as well as -- the memory required is proportional to the number of directories in the -- tree. -- -- When new directories are created under the tree they are added to the watch -- on receiving the directory create event. However, the creation of a dir and -- adding a watch for it is not atomic. The implementation takes care of this -- and makes sure that watches are added for all directories. However, In the -- mean time, the directory may have received more events which may get lost. -- Handling of any such lost events is yet to be implemented. -- -- See the Linux __inotify__ man page for more details. -- -- /Pre-release/ -- watchTreesWith :: (Config -> Config) -> NonEmpty (Array Word8) -> SerialT IO Event watchTreesWith f paths = S.bracket before after (watchToStream cfg) where cfg = f defaultConfig before = liftIO $ openWatch cfg paths after = liftIO . closeWatch -- | Like 'watchTreesWith' but uses the 'defaultConfig' options. -- -- @ -- watchTrees = watchTreesWith id -- @ -- watchTrees :: NonEmpty (Array Word8) -> SerialT IO Event watchTrees = watchTreesWith id ------------------------------------------------------------------------------- -- Examine event stream ------------------------------------------------------------------------------- -- | Get the watch root corresponding to the 'Event'. -- -- Note that if a path was moved after adding to the watch, this will give the -- original path and not the new path after moving. -- -- TBD: we can possibly update the watch root on a move self event. -- -- /Pre-release/ -- getRoot :: Event -> Array Word8 getRoot Event{..} = if (eventWd >= 1) then case Map.lookup (fromIntegral eventWd) eventMap of Just path -> fst path Nothing -> error $ "Bug: getRoot: No path found corresponding to the " ++ "watch descriptor " ++ show eventWd else A.fromList [] -- XXX should we use a Maybe here? -- | Get the file system object path for which the event is generated, relative -- to the watched root. The path is a "/" separated array of bytes. -- -- /Pre-release/ -- getRelPath :: Event -> Array Word8 getRelPath Event{..} = eventRelPath -- | Get the absolute file system object path for which the event is generated. -- The path is a "/" separated array of bytes. -- -- /Pre-release/ -- getAbsPath :: Event -> Array Word8 getAbsPath ev = getRoot ev <> getRelPath ev -- XXX should we use a Maybe? -- | Cookie is set when a rename occurs. The cookie value can be used to -- connect the 'isMovedFrom' and 'isMovedTo' events, if both the events belong -- to the same move operation then they will have the same cookie value. -- -- /Pre-release/ -- getCookie :: Event -> Cookie getCookie Event{..} = Cookie eventCookie ------------------------------------------------------------------------------- -- Event types ------------------------------------------------------------------------------- getFlag :: Word32 -> Event -> Bool getFlag mask Event{..} = eventFlags .&. mask /= 0 ------------------------------------------------------------------------------- -- Error events ------------------------------------------------------------------------------- foreign import capi "sys/inotify.h value IN_Q_OVERFLOW" iN_Q_OVERFLOW :: Word32 -- XXX rename to isQOverflowed or hasOverflowed? -- -- macOS overflow API is more specific, it tells which paths have lost the -- events due to overflow. -- -- | Event queue overflowed (WD is invalid for this event) and we may have lost -- some events.. The user application must scan everything under the watched -- paths to know the current state. -- -- /Pre-release/ -- isOverflow :: Event -> Bool isOverflow = getFlag iN_Q_OVERFLOW ------------------------------------------------------------------------------- -- Events affecting the watched path only ------------------------------------------------------------------------------- foreign import capi "sys/inotify.h value IN_IGNORED" iN_IGNORED :: Word32 -- Compare with isRootChanged on macOS. isRootChanged includes all these cases. -- -- | A path was removed from the watch explicitly using 'removeFromWatch' or -- automatically (file was deleted, or filesystem was unmounted). -- -- /Occurs only for a watched path/ -- -- /Pre-release/ -- isRootUnwatched :: Event -> Bool isRootUnwatched = getFlag iN_IGNORED -- | Watched file/directory was itself deleted. (This event also occurs if an -- object is moved to another filesystem, since mv(1) in effect copies the file -- to the other filesystem and then deletes it from the original filesystem.) -- In addition, an 'isRootUnwatched' event will subsequently be generated -- for the watch descriptor. -- -- /Occurs only for a watched path/ -- -- /Pre-release/ -- isRootDeleted :: Event -> Bool isRootDeleted = getFlag iN_DELETE_SELF -- | Watched file/directory was itself moved within the file system. -- -- /Occurs only for a watched path/ -- -- /Pre-release/ -- isRootMoved :: Event -> Bool isRootMoved = getFlag iN_MOVE_SELF foreign import capi "sys/inotify.h value IN_UNMOUNT" iN_UNMOUNT :: Word32 -- | Filesystem containing watched object was unmounted. In addition, an -- 'isRootUnwatched' event will subsequently be generated for the watch -- descriptor. -- -- /Occurs only for a watched path/ -- -- /Pre-release/ -- isRootUnmounted :: Event -> Bool isRootUnmounted = getFlag iN_UNMOUNT ------------------------------------------------------------------------------- -- Metadata change Events ------------------------------------------------------------------------------- -- macOS has multiple APIs for metadata change for different metadata. -- -- | Determine whether the event indicates inode metadata change for an object -- contained within the monitored path. -- -- Metadata change may include, permissions (e.g., chmod(2)), timestamps -- (e.g., utimensat(2)), extended attributes (setxattr(2)), link count (since -- Linux 2.6.25; e.g., for the target of link(2) and for unlink(2)), and -- user/group ID (e.g., chown(2)). -- -- /Can occur for watched path or a file inside it/ -- -- /Pre-release/ -- isMetadataChanged :: Event -> Bool isMetadataChanged = getFlag iN_ATTRIB ------------------------------------------------------------------------------- -- Access ------------------------------------------------------------------------------- -- | File was accessed (e.g. read, execve). -- -- /Occurs only for a file inside the watched directory/ -- -- /Pre-release/ -- isAccessed :: Event -> Bool isAccessed = getFlag iN_ACCESS -- | File or directory was opened. -- -- /Occurs only for a file inside the watched directory/ -- -- /Pre-release/ -- isOpened :: Event -> Bool isOpened = getFlag iN_OPEN -- | File opened for writing was closed. -- -- /Occurs only for a file inside the watched directory/ -- -- /Pre-release/ -- isWriteClosed :: Event -> Bool isWriteClosed = getFlag iN_CLOSE_WRITE -- XXX what if it was opened for append? Does NOWRITE mean all cases where the -- mode was not write? A dir open comes in this category? -- -- | File or directory opened for read but not write was closed. -- -- /Can occur for watched path or a file inside it/ -- -- /Pre-release/ -- isNonWriteClosed :: Event -> Bool isNonWriteClosed = getFlag iN_CLOSE_NOWRITE ------------------------------------------------------------------------------- -- CRUD Events ------------------------------------------------------------------------------- -- On macOS this is not generated on hard linking but on Linux it is. -- -- | File/directory created in watched directory (e.g., open(2) O_CREAT, -- mkdir(2), link(2), symlink(2), bind(2) on a UNIX domain socket). -- -- /Occurs only for an object inside the watched directory/ -- -- /Pre-release/ -- isCreated :: Event -> Bool isCreated = getFlag iN_CREATE -- | File/directory deleted from watched directory. -- -- /Occurs only for an object inside the watched directory/ -- -- /Pre-release/ -- isDeleted :: Event -> Bool isDeleted = getFlag iN_DELETE -- XXX what if an object is moved in from outside or moved out of the monitored -- dir? -- -- | Generated for the original path when an object is moved from under a -- monitored directory. -- -- /Occurs only for an object inside the watched directory/ -- -- /Pre-release/ -- isMovedFrom :: Event -> Bool isMovedFrom = getFlag iN_MOVED_FROM -- | Generated for the new path when an object is moved under a monitored -- directory. -- -- /Occurs only for an object inside the watched directory/ -- -- /Pre-release/ -- isMovedTo :: Event -> Bool isMovedTo = getFlag iN_MOVED_TO -- | Determine whether the event indicates modification of an object within the -- monitored path. This event is generated only for files and not directories. -- -- /Occurs only for an object inside the watched directory/ -- -- /Pre-release/ -- isModified :: Event -> Bool isModified = getFlag iN_MODIFY ------------------------------------------------------------------------------- -- Information about path type (applicable only when 'setFileEvents' is 'On') ------------------------------------------------------------------------------- foreign import capi "sys/inotify.h value IN_ISDIR" iN_ISDIR :: Word32 -- | Determine whether the event is for a directory path. -- -- /Pre-release/ -- isDir :: Event -> Bool isDir = getFlag iN_ISDIR ------------------------------------------------------------------------------- -- Debugging ------------------------------------------------------------------------------- -- | Convert an 'Event' record to a String representation. showEvent :: Event -> String showEvent ev@Event{..} = "--------------------------" ++ "\nWd = " ++ show eventWd ++ "\nRoot = " ++ show (utf8ToString $ getRoot ev) ++ "\nRelative Path = " ++ show (utf8ToString $ getRelPath ev) ++ "\nAbsolute Path = " ++ show (utf8ToString $ getAbsPath ev) ++ "\nCookie = " ++ show (getCookie ev) ++ "\nFlags " ++ show eventFlags ++ showev isOverflow "Overflow" ++ showev isRootUnwatched "RootUnwatched" ++ showev isRootDeleted "RootDeleted" ++ showev isRootMoved "RootMoved" ++ showev isRootUnmounted "RootUnmounted" ++ showev isMetadataChanged "MetadataChanged" ++ showev isAccessed "Accessed" ++ showev isOpened "Opened" ++ showev isWriteClosed "WriteClosed" ++ showev isNonWriteClosed "NonWriteClosed" ++ showev isCreated "Created" ++ showev isDeleted "Deleted" ++ showev isModified "Modified" ++ showev isMovedFrom "MovedFrom" ++ showev isMovedTo "MovedTo" ++ showev isDir "Dir" ++ "\n" where showev f str = if f ev then "\n" ++ str else "" #else #warning "Disabling module Streamly.Internal.FileSystem.Event.Linux. Does not support kernels older than 2.6.36." module Streamly.Internal.FileSystem.Event.Linux () where #endif