git-annex/Annex/ReplaceFile.hs
Joey Hess 23c6e350cb
improve createDirectoryUnder to allow alternate top directories
This should not change the behavior of it, unless there are multiple top
directories, and then it should behave the same as if there was a single
top directory that was actually above the directory to be created.

Sponsored-by: Dartmouth College's Datalad project
2022-08-12 12:52:37 -04:00

87 lines
3 KiB
Haskell

{- git-annex file replacing
-
- Copyright 2013-2021 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.ReplaceFile (
replaceGitAnnexDirFile,
replaceGitDirFile,
replaceWorkTreeFile,
replaceFile,
replaceFile',
) where
import Annex.Common
import Annex.Tmp
import Annex.Perms
import Git
import Utility.Tmp.Dir
import Utility.Directory.Create
#ifndef mingw32_HOST_OS
import Utility.Path.Max
#endif
{- replaceFile on a file located inside the gitAnnexDir. -}
replaceGitAnnexDirFile :: FilePath -> (FilePath -> Annex a) -> Annex a
replaceGitAnnexDirFile = replaceFile createAnnexDirectory
{- replaceFile on a file located inside the .git directory. -}
replaceGitDirFile :: FilePath -> (FilePath -> Annex a) -> Annex a
replaceGitDirFile = replaceFile $ \dir -> do
top <- fromRepo localGitDir
liftIO $ createDirectoryUnder [top] dir
{- replaceFile on a worktree file. -}
replaceWorkTreeFile :: FilePath -> (FilePath -> Annex a) -> Annex a
replaceWorkTreeFile = replaceFile createWorkTreeDirectory
{- 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.
-
- The createdirectory action is only run when moving the file into place
- fails, and can create any parent directory structure needed.
-}
replaceFile :: (RawFilePath -> Annex ()) -> FilePath -> (FilePath -> Annex a) -> Annex a
replaceFile createdirectory file action = replaceFile' createdirectory file (const True) action
replaceFile' :: (RawFilePath -> Annex ()) -> FilePath -> (a -> Bool) -> (FilePath -> Annex a) -> Annex a
replaceFile' createdirectory file checkres action = withOtherTmp $ \othertmpdir -> do
let othertmpdir' = fromRawFilePath othertmpdir
#ifndef mingw32_HOST_OS
-- Use part of the filename as the template for the temp
-- directory. This does not need to be unique, but it
-- makes it more clear what this temp directory is for.
filemax <- liftIO $ fileNameLengthLimit othertmpdir'
let basetmp = take (filemax `div` 2) (takeFileName file)
#else
-- Windows has limits on the whole path length, so keep
-- it short.
let basetmp = "t"
#endif
withTmpDirIn othertmpdir' basetmp $ \tmpdir -> do
let tmpfile = tmpdir </> basetmp
r <- action tmpfile
when (checkres r) $
replaceFileFrom (toRawFilePath tmpfile) (toRawFilePath file) createdirectory
return r
replaceFileFrom :: RawFilePath -> RawFilePath -> (RawFilePath -> Annex ()) -> Annex ()
replaceFileFrom src dest createdirectory = go `catchIO` fallback
where
go = liftIO $ moveFile src dest
fallback _ = do
createdirectory (parentDir dest)
go