blob: b6126ba7eeb513ab5d0a3bfe347308d5ba5ebf59 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
{- 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 IO 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
|
