64ccb4734e
It will then proceed to add the file the same as if it were any other file containing possibly annexable content. Usually the file is one that was annexed before, so the new, probably corrupt content will also be added to the annex. If the file was not annexed before, the content will be added to git. It's not possible for the smudge filter to throw an error here, because git then just adds the file to git anyway. Sponsored-by: Dartmouth College's Datalad project
440 lines
16 KiB
Haskell
440 lines
16 KiB
Haskell
{- git-annex links to content
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-
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- On file systems that support them, symlinks are used.
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-
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- On other filesystems, git instead stores the symlink target in a regular
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- file.
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-
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- Pointer files are used instead of symlinks for unlocked files.
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-
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- Copyright 2013-2022 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, BangPatterns, OverloadedStrings #-}
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module Annex.Link where
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import Annex.Common
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import qualified Annex
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import qualified Annex.Queue
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import qualified Git.Queue
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import qualified Git.UpdateIndex
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import qualified Git.Index
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import qualified Git.LockFile
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import qualified Git.Env
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import qualified Git
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import Git.Types
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import Git.FilePath
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import Git.Config
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import Annex.HashObject
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import Annex.InodeSentinal
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import Annex.PidLock
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import Utility.FileMode
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import Utility.InodeCache
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import Utility.Tmp.Dir
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import Utility.CopyFile
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import Utility.Tuple
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import qualified Database.Keys.Handle
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import qualified Utility.RawFilePath as R
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import qualified Data.ByteString as S
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import qualified Data.ByteString.Char8 as S8
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import qualified Data.ByteString.Lazy as L
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import qualified System.FilePath.ByteString as P
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type LinkTarget = S.ByteString
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{- Checks if a file is a link to a key. -}
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isAnnexLink :: RawFilePath -> Annex (Maybe Key)
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isAnnexLink file = maybe Nothing parseLinkTargetOrPointer <$> getAnnexLinkTarget file
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{- Gets the link target of a symlink.
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-
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- On a filesystem that does not support symlinks, fall back to getting the
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- link target by looking inside the file.
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-
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- Returns Nothing if the file is not a symlink, or not a link to annex
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- content.
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-}
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getAnnexLinkTarget :: RawFilePath -> Annex (Maybe LinkTarget)
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getAnnexLinkTarget f = getAnnexLinkTarget' f
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=<< (coreSymlinks <$> Annex.getGitConfig)
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{- Pass False to force looking inside file, for when git checks out
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- symlinks as plain files. -}
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getAnnexLinkTarget' :: RawFilePath -> Bool -> Annex (Maybe S.ByteString)
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getAnnexLinkTarget' file coresymlinks = if coresymlinks
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then check probesymlink $
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return Nothing
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else check probesymlink $
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check probefilecontent $
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return Nothing
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where
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check getlinktarget fallback =
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liftIO (catchMaybeIO getlinktarget) >>= \case
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Just l
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| isLinkToAnnex l -> return (Just l)
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| otherwise -> return Nothing
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Nothing -> fallback
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probesymlink = R.readSymbolicLink file
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probefilecontent = withFile (fromRawFilePath file) ReadMode $ \h -> do
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s <- S.hGet h maxSymlinkSz
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-- If we got the full amount, the file is too large
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-- to be a symlink target.
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return $ if S.length s == maxSymlinkSz
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then mempty
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else
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-- If there are any NUL or newline
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-- characters, or whitespace, we
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-- certainly don't have a symlink to a
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-- git-annex key.
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if any (`S8.elem` s) ("\0\n\r \t" :: [Char])
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then mempty
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else s
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makeAnnexLink :: LinkTarget -> RawFilePath -> Annex ()
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makeAnnexLink = makeGitLink
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{- Creates a link on disk.
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-
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- On a filesystem that does not support symlinks, writes the link target
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- to a file. Note that git will only treat the file as a symlink if
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- it's staged as such, so use addAnnexLink when adding a new file or
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- modified link to git.
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-}
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makeGitLink :: LinkTarget -> RawFilePath -> Annex ()
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makeGitLink linktarget file = ifM (coreSymlinks <$> Annex.getGitConfig)
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( liftIO $ do
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void $ tryIO $ R.removeLink file
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R.createSymbolicLink linktarget file
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, liftIO $ S.writeFile (fromRawFilePath file) linktarget
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)
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{- Creates a link on disk, and additionally stages it in git. -}
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addAnnexLink :: LinkTarget -> RawFilePath -> Annex ()
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addAnnexLink linktarget file = do
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makeAnnexLink linktarget file
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stageSymlink file =<< hashSymlink linktarget
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{- Injects a symlink target into git, returning its Sha. -}
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hashSymlink :: LinkTarget -> Annex Sha
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hashSymlink = hashBlob . toInternalGitPath
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{- Stages a symlink to an annexed object, using a Sha of its target. -}
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stageSymlink :: RawFilePath -> Sha -> Annex ()
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stageSymlink file sha =
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Annex.Queue.addUpdateIndex =<<
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inRepo (Git.UpdateIndex.stageSymlink file sha)
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{- Injects a pointer file content into git, returning its Sha. -}
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hashPointerFile :: Key -> Annex Sha
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hashPointerFile key = hashBlob $ formatPointer key
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{- Stages a pointer file, using a Sha of its content -}
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stagePointerFile :: RawFilePath -> Maybe FileMode -> Sha -> Annex ()
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stagePointerFile file mode sha =
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Annex.Queue.addUpdateIndex =<<
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inRepo (Git.UpdateIndex.stageFile sha treeitemtype $ fromRawFilePath file)
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where
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treeitemtype
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| maybe False isExecutable mode = TreeExecutable
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| otherwise = TreeFile
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writePointerFile :: RawFilePath -> Key -> Maybe FileMode -> IO ()
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writePointerFile file k mode = do
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S.writeFile (fromRawFilePath file) (formatPointer k)
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maybe noop (setFileMode $ fromRawFilePath file) mode
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newtype Restage = Restage Bool
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{- Restage pointer file. This is used after updating a worktree file
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- when content is added/removed, to prevent git status from showing
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- it as modified.
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-
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- Asks git to refresh its index information for the file.
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- That in turn runs the clean filter on the file; when the clean
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- filter produces the same pointer that was in the index before, git
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- realizes that the file has not actually been modified.
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-
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- Note that, if the pointer file is staged for deletion, or has different
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- content than the current worktree content staged, this won't change
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- that. So it's safe to call at any time and any situation.
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-
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- If the index is known to be locked (eg, git add has run git-annex),
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- that would fail. Restage False will prevent the index being updated.
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- Will display a message to help the user understand why
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- the file will appear to be modified.
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-
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- This uses the git queue, so the update is not performed immediately,
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- and this can be run multiple times cheaply.
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-
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- The InodeCache is for the worktree file. It is used to detect when
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- the worktree file is changed by something else before git update-index
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- gets to look at it.
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-}
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restagePointerFile :: Restage -> RawFilePath -> InodeCache -> Annex ()
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restagePointerFile (Restage False) f _ =
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toplevelWarning True $ unableToRestage $ Just $ fromRawFilePath f
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restagePointerFile (Restage True) f orig = withTSDelta $ \tsd ->
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-- Avoid refreshing the index if run by the
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-- smudge clean filter, because git uses that when
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-- it's already refreshing the index, probably because
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-- this very action is running. Running it again would likely
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-- deadlock.
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unlessM (Annex.getState Annex.insmudgecleanfilter) $ do
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-- update-index is documented as picky about "./file" and it
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-- fails on "../../repo/path/file" when cwd is not in the repo
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-- being acted on. Avoid these problems with an absolute path.
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absf <- liftIO $ absPath f
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Annex.Queue.addFlushAction runner [(absf, isunmodified tsd, inodeCacheFileSize orig)]
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where
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isunmodified tsd = genInodeCache f tsd >>= return . \case
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Nothing -> False
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Just new -> compareStrong orig new
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-- Other changes to the files may have been staged before this
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-- gets a chance to run. To avoid a race with any staging of
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-- changes, first lock the index file. Then run git update-index
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-- on all still-unmodified files, using a copy of the index file,
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-- to bypass the lock. Then replace the old index file with the new
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-- updated index file.
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runner :: Git.Queue.FlushActionRunner Annex
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runner = Git.Queue.FlushActionRunner "restagePointerFile" $ \r l -> do
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-- Flush any queued changes to the keys database, so they
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-- are visible to child processes.
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-- The database is closed because that may improve behavior
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-- when run in Windows's WSL1, which has issues with
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-- multiple writers to SQL databases.
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liftIO . Database.Keys.Handle.closeDbHandle
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=<< Annex.getRead Annex.keysdbhandle
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realindex <- liftIO $ Git.Index.currentIndexFile r
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let lock = fromRawFilePath (Git.Index.indexFileLock realindex)
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lockindex = liftIO $ catchMaybeIO $ Git.LockFile.openLock' lock
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unlockindex = liftIO . maybe noop Git.LockFile.closeLock
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showwarning = warning $ unableToRestage Nothing
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go Nothing = showwarning
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go (Just _) = withTmpDirIn (fromRawFilePath $ Git.localGitDir r) "annexindex" $ \tmpdir -> do
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let tmpindex = tmpdir </> "index"
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let updatetmpindex = do
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r' <- liftIO $ Git.Env.addGitEnv r Git.Index.indexEnv
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=<< Git.Index.indexEnvVal (toRawFilePath tmpindex)
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-- Avoid git warning about CRLF munging.
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let r'' = r' { gitGlobalOpts = gitGlobalOpts r' ++
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[ Param "-c"
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, Param $ "core.safecrlf=" ++ boolConfig False
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] }
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configfilterprocess l $ runsGitAnnexChildProcessViaGit' r'' $ \r''' ->
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liftIO $ Git.UpdateIndex.refreshIndex r''' $ \feed ->
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forM_ l $ \(f', checkunmodified, _) ->
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whenM checkunmodified $
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feed f'
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let replaceindex = catchBoolIO $ do
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moveFile tmpindex (fromRawFilePath realindex)
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return True
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ok <- liftIO (createLinkOrCopy (fromRawFilePath realindex) tmpindex)
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<&&> updatetmpindex
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<&&> liftIO replaceindex
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unless ok showwarning
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bracket lockindex unlockindex go
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{- filter.annex.process configured to use git-annex filter-process
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- is sometimes faster and sometimes slower than using
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- git-annex smudge. The latter is run once per file, while
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- the former has the content of files piped to it.
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-}
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filterprocessfaster l =
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let numfiles = genericLength l
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sizefiles = sum (map thd3 l)
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-- estimates based on benchmarking
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estimate_enabled = sizefiles `div` 191739611
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estimate_disabled = numfiles `div` 7
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in estimate_enabled <= estimate_disabled
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{- This disables filter.annex.process if it's set when it would
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- probably not be faster to use it. Unfortunately, simply
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- passing -c filter.annex.process= also prevents git from
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- running the smudge filter, so .git/config has to be modified
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- to disable it. The modification is reversed at the end. In
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- case this process is terminated early, the next time this
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- runs it will take care of reversing the modification.
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-}
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configfilterprocess l = bracket setup cleanup . const
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where
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setup
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| filterprocessfaster l = return Nothing
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| otherwise = fromRepo (Git.Config.getMaybe ck) >>= \case
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Nothing -> return Nothing
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Just v -> do
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void $ inRepo (Git.Config.change ckd (fromConfigValue v))
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void $ inRepo (Git.Config.unset ck)
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return (Just v)
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cleanup (Just v) = do
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void $ inRepo $ Git.Config.change ck (fromConfigValue v)
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void $ inRepo (Git.Config.unset ckd)
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cleanup Nothing = fromRepo (Git.Config.getMaybe ckd) >>= \case
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Nothing -> return ()
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Just v -> do
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whenM (isNothing <$> fromRepo (Git.Config.getMaybe ck)) $
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void $ inRepo (Git.Config.change ck (fromConfigValue v))
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void $ inRepo (Git.Config.unset ckd)
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ck = ConfigKey "filter.annex.process"
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ckd = ConfigKey "filter.annex.process-temp-disabled"
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unableToRestage :: Maybe FilePath -> String
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unableToRestage mf = unwords
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[ "git status will show " ++ fromMaybe "some files" mf
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, "to be modified, since content availability has changed"
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, "and git-annex was unable to update the index."
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, "This is only a cosmetic problem affecting git status; git add,"
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, "git commit, etc won't be affected."
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, "To fix the git status display, you can run:"
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, "git update-index -q --refresh " ++ fromMaybe "<file>" mf
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]
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{- Parses a symlink target or a pointer file to a Key.
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-
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- Makes sure that the pointer file is valid, including not being longer
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- than the maximum allowed size of a valid pointer file, and that any
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- subsequent lines after the first contain the validPointerLineTag.
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- If a valid pointer file gets some other data appended to it, it should
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- never be considered valid, unless that data happened to itself be a
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- valid pointer file.
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-}
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parseLinkTargetOrPointer :: S.ByteString -> Maybe Key
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parseLinkTargetOrPointer = either (const Nothing) id
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. parseLinkTargetOrPointer'
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data InvalidAppendedPointerFile = InvalidAppendedPointerFile
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parseLinkTargetOrPointer' :: S.ByteString -> Either InvalidAppendedPointerFile (Maybe Key)
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parseLinkTargetOrPointer' b =
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let (firstline, rest) = S8.span (/= '\n') b
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in case parsekey $ droptrailing '\r' firstline of
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Just k
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| S.length b > maxValidPointerSz -> Left InvalidAppendedPointerFile
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| restvalid (dropleading '\n' rest) -> Right (Just k)
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| otherwise -> Left InvalidAppendedPointerFile
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Nothing -> Right Nothing
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where
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parsekey l
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| isLinkToAnnex l = fileKey $ snd $ S8.breakEnd pathsep l
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| otherwise = Nothing
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restvalid r
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| S.null r = True
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| otherwise =
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let (l, r') = S8.span (/= '\n') r
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in validPointerLineTag `S.isInfixOf` l
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&& (not (S8.null r') && S8.head r' == '\n')
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&& restvalid (S8.tail r')
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dropleading c l
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| S.null l = l
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| S8.head l == c = S8.tail l
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| otherwise = l
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droptrailing c l
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| S.null l = l
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| S8.last l == c = S8.init l
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| otherwise = l
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pathsep '/' = True
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#ifdef mingw32_HOST_OS
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pathsep '\\' = True
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#endif
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pathsep _ = False
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{- Avoid looking at more of the lazy ByteString than necessary since it
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- could be reading from a large file that is not a pointer file. -}
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parseLinkTargetOrPointerLazy :: L.ByteString -> Maybe Key
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parseLinkTargetOrPointerLazy = either (const Nothing) id
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. parseLinkTargetOrPointerLazy'
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parseLinkTargetOrPointerLazy' :: L.ByteString -> Either InvalidAppendedPointerFile (Maybe Key)
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parseLinkTargetOrPointerLazy' b =
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let b' = L.take (fromIntegral maxPointerSz) b
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in parseLinkTargetOrPointer' (L.toStrict b')
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formatPointer :: Key -> S.ByteString
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formatPointer k = prefix <> keyFile k <> nl
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where
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prefix = toInternalGitPath $ P.pathSeparator `S.cons` objectDir'
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nl = S8.singleton '\n'
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{- Maximum size of a file that could be a pointer to a key.
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- Check to avoid buffering really big files in git into
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- memory when reading files that may be pointers.
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-
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- 8192 bytes is plenty for a pointer to a key. This adds some additional
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- padding to allow for pointer files that have lines of additional data
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- after the key.
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-
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- One additional byte is used to detect when a valid pointer file
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- got something else appended to it.
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-}
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maxPointerSz :: Int
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maxPointerSz = maxValidPointerSz + 1
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{- Maximum size of a valid pointer files is 32kb. -}
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maxValidPointerSz :: Int
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maxValidPointerSz = 32768
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maxSymlinkSz :: Int
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maxSymlinkSz = 8192
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{- Checks if a worktree file is a pointer to a key.
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-
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- Unlocked files whose content is present are not detected by this.
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-
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- It's possible, though unlikely, that an annex symlink points to
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- an object that looks like a pointer file. Or that a non-annex
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- symlink does. Avoids a false positive in those cases.
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- -}
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isPointerFile :: RawFilePath -> IO (Maybe Key)
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isPointerFile f = catchDefaultIO Nothing $
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#if defined(mingw32_HOST_OS)
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checkcontentfollowssymlinks -- no symlinks supported on windows
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#else
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#if MIN_VERSION_unix(2,8,0)
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bracket
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(openFd (fromRawFilePath f) ReadOnly (defaultFileFlags { nofollow = True }) Nothing)
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closeFd
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(\fd -> readhandle =<< fdToHandle fd)
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#else
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ifM (isSymbolicLink <$> R.getSymbolicLinkStatus f)
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( return Nothing
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, checkcontentfollowssymlinks
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)
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#endif
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#endif
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where
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checkcontentfollowssymlinks =
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withFile (fromRawFilePath f) ReadMode readhandle
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readhandle h = parseLinkTargetOrPointer <$> S.hGet h maxPointerSz
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{- Checks a symlink target or pointer file first line to see if it
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- appears to point to annexed content.
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-
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- We only look for paths inside the .git directory, and not at the .git
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- directory itself, because GIT_DIR may cause a directory name other
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- than .git to be used.
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-}
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isLinkToAnnex :: S.ByteString -> Bool
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isLinkToAnnex s = p `S.isInfixOf` s
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#ifdef mingw32_HOST_OS
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-- '/' is used inside pointer files on Windows, not the native '\'
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|| p' `S.isInfixOf` s
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#endif
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where
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p = P.pathSeparator `S.cons` objectDir'
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#ifdef mingw32_HOST_OS
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p' = toInternalGitPath p
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#endif
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{- String that must appear on every line of a valid pointer file. -}
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validPointerLineTag :: S.ByteString
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validPointerLineTag = "/annex/"
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