git-annex/Command/Add.hs
Joey Hess c981ccc077 add: Prevent (most) modifications from being made to a file while it is being added to the annex.
Anything that tries to open the file for write, or delete the file,
or replace it with something else, will not affect the add.

Only if a process has the file open for write before add starts
can it still change it while (or after) it's added to the annex.
(fsck will catch this later of course)
2012-06-05 20:28:34 -04:00

111 lines
3.3 KiB
Haskell

{- git-annex command
-
- Copyright 2010 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Command.Add where
import Common.Annex
import Annex.Exception
import Command
import qualified Annex
import qualified Annex.Queue
import Backend
import Logs.Location
import Annex.Content
import Annex.Perms
import Utility.Touch
import Utility.FileMode
def :: [Command]
def = [command "add" paramPaths seek "add files to annex"]
{- Add acts on both files not checked into git yet, and unlocked files. -}
seek :: [CommandSeek]
seek = [withFilesNotInGit start, withFilesUnlocked start]
{- The add subcommand annexes a file, storing it in a backend, and then
- moving it into the annex directory and setting up the symlink pointing
- to its content. -}
start :: FilePath -> CommandStart
start file = notBareRepo $ ifAnnexed file fixup add
where
add = do
s <- liftIO $ getSymbolicLinkStatus file
if isSymbolicLink s || not (isRegularFile s)
then stop
else do
showStart "add" file
next $ perform file
fixup (key, _) = do
-- fixup from an interrupted add; the symlink
-- is present but not yet added to git
showStart "add" file
liftIO $ removeFile file
next $ next $ cleanup file key =<< inAnnex key
{- The file that's being added is locked down before a key is generated,
- to prevent it from being modified in between. It's hard linked into a
- temporary location, and its writable bits are removed. It could still be
- written to by a process that already has it open for writing. -}
perform :: FilePath -> CommandPerform
perform file = do
liftIO $ preventWrite file
tmp <- fromRepo gitAnnexTmpDir
createAnnexDirectory tmp
pid <- liftIO getProcessID
let tmpfile = tmp </> "add" ++ show pid ++ "." ++ takeFileName file
nuke tmpfile
liftIO $ createLink file tmpfile
let source = KeySource { keyFilename = file, contentLocation = tmpfile }
backend <- chooseBackend file
genKey source backend >>= go tmpfile
where
go _ Nothing = stop
go tmpfile (Just (key, _)) = do
handle (undo file key) $ moveAnnex key tmpfile
nuke file
next $ cleanup file key True
nuke :: FilePath -> Annex ()
nuke file = liftIO $ whenM (doesFileExist file) $ removeFile file
{- On error, put the file back so it doesn't seem to have vanished.
- This can be called before or after the symlink is in place. -}
undo :: FilePath -> Key -> IOException -> Annex a
undo file key e = do
whenM (inAnnex key) $ do
nuke file
handle tryharder $ fromAnnex key file
logStatus key InfoMissing
throw e
where
-- fromAnnex could fail if the file ownership is weird
tryharder :: IOException -> Annex ()
tryharder _ = do
src <- inRepo $ gitAnnexLocation key
liftIO $ moveFile src file
cleanup :: FilePath -> Key -> Bool -> CommandCleanup
cleanup file key hascontent = do
handle (undo file key) $ do
link <- calcGitLink file key
liftIO $ createSymbolicLink link file
when hascontent $ do
logStatus key InfoPresent
-- touch the symlink to have the same mtime as the
-- file it points to
liftIO $ do
mtime <- modificationTime <$> getFileStatus file
touch file (TimeSpec mtime) False
params <- ifM (Annex.getState Annex.force)
( return [Param "-f"]
, return []
)
Annex.Queue.add "add" (params++[Param "--"]) [file]
return True