git-annex/Annex/Ssh.hs
Joey Hess 7f7c31df1c type based git config handling
Now there's a Config type, that's extracted from the git config at startup.
Note that laziness means that individual config values are only looked up
and parsed on demand, and so we get implicit memoization for all of them.
So this is not only prettier and more type safe, it optimises several
places that didn't have explicit memoization before. As well as getting rid
of the ugly explicit memoization code.

Not yet done for annex.<remote>.* configuration settings.
2012-12-29 23:10:18 -04:00

142 lines
4.2 KiB
Haskell

{- git-annex ssh interface, with connection caching
-
- Copyright 2012 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 Common.Annex
import Annex.LockPool
import Annex.Perms
#ifndef WITH_OLD_SSH
import qualified Build.SysConfig as SysConfig
import qualified Annex
#endif
{- 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 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
sshInfo :: (String, Maybe Integer) -> Annex (Maybe FilePath, [CommandParam])
sshInfo (host, port) = ifM caching
( do
dir <- fromRepo gitAnnexSshDir
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, [])
, return (Nothing, [])
)
where
#ifdef WITH_OLD_SSH
caching = return False
#else
caching = fromMaybe SysConfig.sshconnectioncaching
. annexSshCaching <$> Annex.getConfig
#endif
cacheParams :: FilePath -> [CommandParam]
cacheParams socketfile =
[ Param "-S", Param socketfile
, Params "-o ControlMaster=auto -o ControlPersist=yes"
]
portParams :: Maybe Integer -> [CommandParam]
portParams Nothing = []
portParams (Just port) = [Param "-p", Param $ show port]
{- Stop any unused ssh processes. -}
sshCleanup :: Annex ()
sshCleanup = do
dir <- fromRepo gitAnnexSshDir
sockets <- filter (not . isLock) <$>
liftIO (catchDefaultIO [] $ dirContents dir)
forM_ sockets cleanup
where
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