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|
{- git-annex ssh interface, with connection caching
-
- Copyright 2012,2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.Ssh (
sshParams,
sshCleanup,
) where
import qualified Data.Map as M
import System.Posix.Env
import Common.Annex
import Annex.LockPool
import Annex.Perms
import qualified Build.SysConfig as SysConfig
import qualified Annex
import Config
{- Generates parameters to ssh to a given host (or user@host) on a given
- port, with connection caching. -}
sshParams :: (String, Maybe Integer) -> [CommandParam] -> Annex [CommandParam]
sshParams (host, port) opts = go =<< sshInfo (host, port)
where
go (Nothing, params) = ret params
go (Just socketfile, params) = do
cleanstale
liftIO $ createDirectoryIfMissing True $ parentDir socketfile
lockFile $ socket2lock socketfile
ret params
ret ps = return $ ps ++ opts ++ portParams port ++
[Param "-T", Param host]
-- If the lock pool is empty, this is the first ssh of this
-- run. There could be stale ssh connections hanging around
-- from a previous git-annex run that was interrupted.
cleanstale = whenM (not . any isLock . M.keys <$> getPool) $
sshCleanup
{- Returns a filename to use for a ssh connection caching socket, and
- parameters to enable ssh connection caching. -}
sshInfo :: (String, Maybe Integer) -> Annex (Maybe FilePath, [CommandParam])
sshInfo (host, port) = go =<< sshCacheDir
where
go Nothing = return (Nothing, [])
go (Just dir) = do
let socketfile = dir </> hostport2socket host port
if valid_unix_socket_path socketfile
then return (Just socketfile, cacheparams socketfile)
else do
socketfile' <- liftIO $ relPathCwdToFile socketfile
if valid_unix_socket_path socketfile'
then return (Just socketfile', cacheparams socketfile')
else return (Nothing, [])
cacheparams :: FilePath -> [CommandParam]
cacheparams socketfile =
[ Param "-S", Param socketfile
, Params "-o ControlMaster=auto -o ControlPersist=yes"
]
{- ssh connection caching creates sockets, so will not work on a
- crippled filesystem. A GIT_ANNEX_TMP_DIR can be provided to use
- a different filesystem. -}
sshCacheDir :: Annex (Maybe FilePath)
sshCacheDir
| SysConfig.sshconnectioncaching = ifM crippledFileSystem
( maybe (return Nothing) usetmpdir =<< gettmpdir
, ifM (fromMaybe True . annexSshCaching <$> Annex.getGitConfig)
( Just <$> fromRepo gitAnnexSshDir
, return Nothing
)
)
| otherwise = return Nothing
where
gettmpdir = liftIO $ getEnv "GIT_ANNEX_TMP_DIR"
usetmpdir tmpdir = liftIO $ catchMaybeIO $ do
createDirectoryIfMissing True tmpdir
return $ tmpdir
portParams :: Maybe Integer -> [CommandParam]
portParams Nothing = []
portParams (Just port) = [Param "-p", Param $ show port]
{- Stop any unused ssh processes. -}
sshCleanup :: Annex ()
sshCleanup = go =<< sshCacheDir
where
go Nothing = noop
go (Just dir) = do
sockets <- filter (not . isLock) <$>
liftIO (catchDefaultIO [] $ dirContents dir)
forM_ sockets cleanup
cleanup socketfile = do
-- Drop any shared lock we have, and take an
-- exclusive lock, without blocking. If the lock
-- succeeds, nothing is using this ssh, and it can
-- be stopped.
let lockfile = socket2lock socketfile
unlockFile lockfile
mode <- annexFileMode
fd <- liftIO $ noUmask mode $
openFd lockfile ReadWrite (Just mode) defaultFileFlags
v <- liftIO $ tryIO $
setLock fd (WriteLock, AbsoluteSeek, 0, 0)
case v of
Left _ -> noop
Right _ -> stopssh socketfile
liftIO $ closeFd fd
stopssh socketfile = do
let (host, port) = socket2hostport socketfile
(_, params) <- sshInfo (host, port)
-- "ssh -O stop" is noisy on stderr even with -q
void $ liftIO $ catchMaybeIO $
withQuietOutput createProcessSuccess $
proc "ssh" $ toCommand $
[ Params "-O stop"
] ++ params ++ [Param host]
-- Cannot remove the lock file; other processes may
-- be waiting on our exclusive lock to use it.
hostport2socket :: String -> Maybe Integer -> FilePath
hostport2socket host Nothing = host
hostport2socket host (Just port) = host ++ "!" ++ show port
socket2hostport :: FilePath -> (String, Maybe Integer)
socket2hostport socket
| null p = (h, Nothing)
| otherwise = (h, readish p)
where
(h, p) = separate (== '!') $ takeFileName socket
socket2lock :: FilePath -> FilePath
socket2lock socket = socket ++ lockExt
isLock :: FilePath -> Bool
isLock f = lockExt `isSuffixOf` f
lockExt :: String
lockExt = ".lock"
{- This is the size of the sun_path component of sockaddr_un, which
- is the limit to the total length of the filename of a unix socket.
-
- On Linux, this is 108. On OSX, 104. TODO: Probe
-}
sizeof_sockaddr_un_sun_path :: Int
sizeof_sockaddr_un_sun_path = 100
{- Note that this looks at the true length of the path in bytes, as it will
- appear on disk. -}
valid_unix_socket_path :: FilePath -> Bool
valid_unix_socket_path f = length (decodeW8 f) < sizeof_sockaddr_un_sun_path
|
