diff options
Diffstat (limited to 'Annex/ReplaceFile.hs')
| -rw-r--r-- | Annex/ReplaceFile.hs | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/Annex/ReplaceFile.hs b/Annex/ReplaceFile.hs index f0dfa5b27..93f807978 100644 --- a/Annex/ReplaceFile.hs +++ b/Annex/ReplaceFile.hs @@ -9,27 +9,32 @@ module Annex.ReplaceFile where import Common.Annex import Annex.Perms +import Annex.Exception {- Replaces a possibly already existing file with a new version, - atomically, by running an action. - - The action is passed a temp file, which it can write to, and once - done the temp file is moved into place. + - + - The action can throw an IO exception, in which case the temp file + - 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 a = do tmpdir <- fromRepo gitAnnexTmpDir - createAnnexDirectory tmpdir - tmpfile <- liftIO $ do + void $ createAnnexDirectory tmpdir + bracketIO (setup tmpdir) nukeFile $ \tmpfile -> do + a tmpfile + liftIO $ catchIO (rename tmpfile file) (fallback tmpfile) + where + setup tmpdir = do (tmpfile, h) <- openTempFileWithDefaultPermissions tmpdir $ takeFileName file hClose h return tmpfile - a tmpfile - liftIO $ do - r <- tryIO $ rename tmpfile file - case r of - Left _ -> do - createDirectoryIfMissing True $ parentDir file - rename tmpfile file - _ -> noop + fallback tmpfile _ = do + createDirectoryIfMissing True $ parentDir file + rename tmpfile file |