git-annex/Command/Lock.hs
Joey Hess 5a98f2d509
avoid creating content directory when locking content
If the content directory does not exist, then it does not make sense to
lock the content file, as it also does not exist, and so it's ok for the
lock operation to fail.

This avoids potential races where the content file exists but is then
deleted/renamed, while another process sees that it exists and goes to
lock it, resulting in a dangling lock file in an otherwise empty object
directory.

Also renamed modifyContent to modifyContentDir since it is not only
necessarily used for modifying content files, but also other files in
the content directory.

Sponsored-by: Dartmouth College's Datalad project
2022-05-16 12:34:56 -04:00

103 lines
2.9 KiB
Haskell

{- git-annex command
-
- Copyright 2010,2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Command.Lock where
import Command
import qualified Annex
import Annex.Content
import Annex.Link
import Annex.InodeSentinal
import Annex.Perms
import Annex.ReplaceFile
import Utility.InodeCache
import qualified Database.Keys
import Annex.Ingest
import Logs.Location
import Git.FilePath
import qualified Utility.RawFilePath as R
cmd :: Command
cmd = withGlobalOptions [jsonOptions, annexedMatchingOptions] $
command "lock" SectionCommon
"undo unlock command"
paramPaths (withParams seek)
seek :: CmdParams -> CommandSeek
seek ps = withFilesInGitAnnex ww seeker =<< workTreeItems ww ps
where
ww = WarnUnmatchLsFiles
seeker = AnnexedFileSeeker
{ startAction = start
, checkContentPresent = Nothing
, usesLocationLog = False
}
start :: SeekInput -> RawFilePath -> Key -> CommandStart
start si file key = ifM (isJust <$> isAnnexLink file)
( stop
, starting "lock" (mkActionItem (key, file)) si $
go =<< liftIO (isPointerFile file)
)
where
go (Just key')
| key' == key = cont
| otherwise = errorModified
go Nothing =
ifM (isUnmodified key file)
( cont
, ifM (Annex.getState Annex.force)
( cont
, errorModified
)
)
cont = perform file key
perform :: RawFilePath -> Key -> CommandPerform
perform file key = do
lockdown =<< calcRepo (gitAnnexLocation key)
addLink (CheckGitIgnore False) file key
=<< withTSDelta (liftIO . genInodeCache file)
next $ return True
where
lockdown obj = do
ifM (isUnmodified key obj)
( breakhardlink obj
, repopulate obj
)
whenM (liftIO $ R.doesPathExist obj) $
freezeContent obj
-- It's ok if the file is hard linked to obj, but if some other
-- associated file is, we need to break that link to lock down obj.
breakhardlink obj = whenM (catchBoolIO $ (> 1) . linkCount <$> liftIO (R.getFileStatus obj)) $ do
mfc <- withTSDelta (liftIO . genInodeCache file)
unlessM (sameInodeCache obj (maybeToList mfc)) $ do
modifyContentDir obj $ replaceGitAnnexDirFile (fromRawFilePath obj) $ \tmp -> do
unlessM (checkedCopyFile key obj (toRawFilePath tmp) Nothing) $
giveup "unable to lock file"
Database.Keys.storeInodeCaches key [obj]
-- Try to repopulate obj from an unmodified associated file.
repopulate obj = modifyContentDir obj $ do
g <- Annex.gitRepo
fs <- map (`fromTopFilePath` g)
<$> Database.Keys.getAssociatedFiles key
mfile <- firstM (isUnmodified key) fs
liftIO $ removeWhenExistsWith R.removeLink obj
case mfile of
Just unmodified ->
ifM (checkedCopyFile key unmodified obj Nothing)
( Database.Keys.storeInodeCaches key [obj]
, lostcontent
)
Nothing -> lostcontent
lostcontent = logStatus key InfoMissing
errorModified :: a
errorModified = giveup "Locking this file would discard any changes you have made to it. Use 'git annex add' to stage your changes. (Or, use --force to override)"