git-annex/Annex/ReplaceFile.hs
Joey Hess 121f5d5b0c
annex.thin
Decided it's too scary to make v6 unlocked files have 1 copy by default,
but that should be available to those who need it. This is consistent with
git-annex not dropping unused content without --force, etc.

* Added annex.thin setting, which makes unlocked files in v6 repositories
  be hard linked to their content, instead of a copy. This saves disk
  space but means any modification of an unlocked file will lose the local
  (and possibly only) copy of the old version.
* Enable annex.thin by default on upgrade from direct mode to v6, since
  direct mode made the same tradeoff.
* fix: Adjusts unlocked files as configured by annex.thin.
2015-12-27 15:59:59 -04:00

43 lines
1.3 KiB
Haskell

{- git-annex file replacing
-
- Copyright 2013-2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.ReplaceFile where
import Common.Annex
import Annex.Perms
import Utility.Tmp
{- Replaces a possibly already existing file with a new version,
- atomically, by running an action.
-
- The action is passed the name of temp file, in a temp directory,
- which it can write to, and once done the temp file is moved into place
- and anything else in the temp directory is deleted.
-
- The action can throw an exception, in which case the temp directory
- will be deleted, and the existing file will be preserved.
-
- Throws an IO exception when it was unable to replace the file.
-}
replaceFile :: FilePath -> (FilePath -> Annex ()) -> Annex ()
replaceFile file action = do
misctmpdir <- fromRepo gitAnnexTmpMiscDir
void $ createAnnexDirectory misctmpdir
filemax <- liftIO $ fileNameLengthLimit misctmpdir
let basetmp = take (filemax `div` 2) (takeFileName file)
withTmpDirIn misctmpdir basetmp $ \tmpdir -> do
let tmpfile = tmpdir </> basetmp
action tmpfile
liftIO $ replaceFileFrom tmpfile file
replaceFileFrom :: FilePath -> FilePath -> IO ()
replaceFileFrom src dest = go `catchIO` fallback
where
go = moveFile src dest
fallback _ = do
createDirectoryIfMissing True $ parentDir dest
go