git-annex/Command/TransferInfo.hs
Joey Hess 10d3b7fc62
Fix reversion introduced in 6.20171214 that caused concurrent transfers to incorrectly fail with "transfer already in progress".
Avoid creating transfer info file before transfer lock is created and
locked.

The wrong order for one thing caused transfer info to be overwritten
when a transfer was already in progress.

But worse, it caused checkTransfer to see the transfer info,
and so lock the transfer lock in order to verify the transfer was not in
progress. Which in a concurrent situation, prevented the transferrer
from locking the transfer lock, so it failed with "transfer already in
progress".

Note that the transferinfo command does not lock the transfer lock
before creating the transfer info. But, that's only run after
recvkey is running, and recvkey does lock the transfer lock, so that
seems more or less ok. (Other than being a super complicated legacy mess
that the P2P code has mostly obsoleted now.)

This commit was supported by the NSF-funded DataLad project.
2018-03-14 18:55:34 -04:00

67 lines
2 KiB
Haskell

{- git-annex command
-
- Copyright 2012 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Command.TransferInfo where
import Command
import Annex.Content
import Types.Transfer
import Logs.Transfer
import qualified CmdLine.GitAnnexShell.Fields as Fields
import Utility.Metered
import Utility.SimpleProtocol
cmd :: Command
cmd = noCommit $
command "transferinfo" SectionPlumbing
"updates sender on number of bytes of content received"
paramKey (withParams seek)
seek :: CmdParams -> CommandSeek
seek = withWords start
{- Security:
-
- The transfer info file contains the user-supplied key, but
- the built-in guards prevent slashes in it from showing up in the filename.
- It also contains the UUID of the remote. But slashes are also filtered
- out of that when generating the filename.
-
- Checks that the key being transferred is inAnnex, to prevent
- malicious spamming of bogus keys. Does not check that a transfer
- of the key is actually in progress, because this could be started
- concurrently with sendkey, and win the race.
-}
start :: [String] -> CommandStart
start (k:[]) = do
case file2key k of
Nothing -> error "bad key"
(Just key) -> whenM (inAnnex key) $ do
afile <- AssociatedFile <$> Fields.getField Fields.associatedFile
u <- maybe (error "missing remoteuuid") toUUID
<$> Fields.getField Fields.remoteUUID
let t = Transfer
{ transferDirection = Upload
, transferUUID = u
, transferKey = key
}
tinfo <- liftIO $ startTransferInfo afile
(update, tfile, createtfile, _) <- mkProgressUpdater t tinfo
createtfile
liftIO $ mapM_ void
[ tryIO $ forever $ do
bytes <- readUpdate
maybe (error "transferinfo protocol error")
(update . toBytesProcessed) bytes
, tryIO $ removeFile tfile
, exitSuccess
]
stop
start _ = giveup "wrong number of parameters"
readUpdate :: IO (Maybe Integer)
readUpdate = maybe Nothing readish <$> getProtocolLine stdin