d9fd205cbb
Minor optimisation, but a win in every case, except for a couple where it's a wash. Note that replaceFile still takes a FilePath, because it needs to operate on Chars to truncate unicode filenames properly.
87 lines
3 KiB
Haskell
87 lines
3 KiB
Haskell
{- git-annex file replacing
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-
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- Copyright 2013-2021 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU AGPL version 3 or higher.
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-}
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{-# LANGUAGE CPP #-}
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module Annex.ReplaceFile (
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replaceGitAnnexDirFile,
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replaceGitDirFile,
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replaceWorkTreeFile,
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replaceFile,
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replaceFile',
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) where
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import Annex.Common
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import Annex.Tmp
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import Annex.Perms
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import Git
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import Utility.Tmp.Dir
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import Utility.Directory.Create
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#ifndef mingw32_HOST_OS
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import Utility.Path.Max
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#endif
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{- replaceFile on a file located inside the gitAnnexDir. -}
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replaceGitAnnexDirFile :: FilePath -> (RawFilePath -> Annex a) -> Annex a
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replaceGitAnnexDirFile = replaceFile createAnnexDirectory
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{- replaceFile on a file located inside the .git directory. -}
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replaceGitDirFile :: FilePath -> (RawFilePath -> Annex a) -> Annex a
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replaceGitDirFile = replaceFile $ \dir -> do
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top <- fromRepo localGitDir
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liftIO $ createDirectoryUnder [top] dir
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{- replaceFile on a worktree file. -}
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replaceWorkTreeFile :: FilePath -> (RawFilePath -> Annex a) -> Annex a
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replaceWorkTreeFile = replaceFile createWorkTreeDirectory
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{- Replaces a possibly already existing file with a new version,
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- atomically, by running an action.
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-
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- The action is passed the name of temp file, in a temp directory,
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- which it can write to, and once done the temp file is moved into place
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- and anything else in the temp directory is deleted.
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-
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- The action can throw an exception, in which case the temp directory
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- will be deleted, and the existing file will be preserved.
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-
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- Throws an IO exception when it was unable to replace the file.
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-
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- The createdirectory action is only run when moving the file into place
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- fails, and can create any parent directory structure needed.
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-}
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replaceFile :: (RawFilePath -> Annex ()) -> FilePath -> (RawFilePath -> Annex a) -> Annex a
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replaceFile createdirectory file action = replaceFile' createdirectory file (const True) action
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replaceFile' :: (RawFilePath -> Annex ()) -> FilePath -> (a -> Bool) -> (RawFilePath -> Annex a) -> Annex a
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replaceFile' createdirectory file checkres action = withOtherTmp $ \othertmpdir -> do
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let othertmpdir' = fromRawFilePath othertmpdir
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#ifndef mingw32_HOST_OS
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-- Use part of the filename as the template for the temp
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-- directory. This does not need to be unique, but it
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-- makes it more clear what this temp directory is for.
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filemax <- liftIO $ fileNameLengthLimit othertmpdir'
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let basetmp = take (filemax `div` 2) (takeFileName file)
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#else
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-- Windows has limits on the whole path length, so keep
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-- it short.
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let basetmp = "t"
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#endif
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withTmpDirIn othertmpdir' basetmp $ \tmpdir -> do
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let tmpfile = toRawFilePath (tmpdir </> basetmp)
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r <- action tmpfile
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when (checkres r) $
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replaceFileFrom tmpfile (toRawFilePath file) createdirectory
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return r
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replaceFileFrom :: RawFilePath -> RawFilePath -> (RawFilePath -> Annex ()) -> Annex ()
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replaceFileFrom src dest createdirectory = go `catchIO` fallback
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where
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go = liftIO $ moveFile src dest
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fallback _ = do
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createdirectory (parentDir dest)
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go
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