git-annex/Annex/Link.hs
Joey Hess e213ef310f git-annex (5.20140717) unstable; urgency=high
* Fix minor FD leak in journal code. Closes: #754608
  * direct: Fix handling of case where a work tree subdirectory cannot
    be written to due to permissions.
  * migrate: Avoid re-checksumming when migrating from hashE to hash backend.
  * uninit: Avoid failing final removal in some direct mode repositories
    due to file modes.
  * S3: Deal with AWS ACL configurations that do not allow creating or
    checking the location of a bucket, but only reading and writing content to
    it.
  * resolvemerge: New plumbing command that runs the automatic merge conflict
    resolver.
  * Deal with change in git 2.0 that made indirect mode merge conflict
    resolution leave behind old files.
  * sync: Fix git sync with local git remotes even when they don't have an
    annex.uuid set. (The assistant already did so.)
  * Set gcrypt-publish-participants when setting up a gcrypt repository,
    to avoid unncessary passphrase prompts.
    This is a security/usability tradeoff. To avoid exposing the gpg key
    ids who can decrypt the repository, users can unset
    gcrypt-publish-participants.
  * Install nautilus hooks even when ~/.local/share/nautilus/ does not yet
    exist, since it is not automatically created for Gnome 3 users.
  * Windows: Move .vbs files out of git\bin, to avoid that being in the
    PATH, which caused some weird breakage. (Thanks, divB)
  * Windows: Fix locking issue that prevented the webapp starting
    (since 5.20140707).

# imported from the archive
2014-07-17 11:27:25 -04:00

108 lines
3.2 KiB
Haskell

{- git-annex links to content
-
- On file systems that support them, symlinks are used.
-
- On other filesystems, git instead stores the symlink target in a regular
- file.
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.Link where
import Common.Annex
import qualified Annex
import qualified Git.HashObject
import qualified Git.UpdateIndex
import qualified Annex.Queue
import Git.Types
import Git.FilePath
type LinkTarget = String
{- Checks if a file is a link to a key. -}
isAnnexLink :: FilePath -> Annex (Maybe Key)
isAnnexLink file = maybe Nothing (fileKey . takeFileName) <$> getAnnexLinkTarget file
{- Gets the link target of a symlink.
-
- On a filesystem that does not support symlinks, fall back to getting the
- link target by looking inside the file.
-
- Returns Nothing if the file is not a symlink, or not a link to annex
- content.
-}
getAnnexLinkTarget :: FilePath -> Annex (Maybe LinkTarget)
getAnnexLinkTarget file = ifM (coreSymlinks <$> Annex.getGitConfig)
( check readSymbolicLink $
return Nothing
, check readSymbolicLink $
check probefilecontent $
return Nothing
)
where
check getlinktarget fallback = do
v <- liftIO $ catchMaybeIO $ getlinktarget file
case v of
Just l
| isLinkToAnnex (fromInternalGitPath l) -> return v
| otherwise -> return Nothing
Nothing -> fallback
probefilecontent f = withFile f ReadMode $ \h -> do
fileEncoding h
-- The first 8k is more than enough to read; link
-- files are small.
s <- take 8192 <$> hGetContents h
-- If we got the full 8k, the file is too large
if length s == 8192
then return ""
else
-- If there are any NUL or newline
-- characters, or whitespace, we
-- certianly don't have a link to a
-- git-annex key.
return $ if any (`elem` s) "\0\n\r \t"
then ""
else s
makeAnnexLink :: LinkTarget -> FilePath -> Annex ()
makeAnnexLink = makeGitLink
{- Creates a link on disk.
-
- On a filesystem that does not support symlinks, writes the link target
- to a file. Note that git will only treat the file as a symlink if
- it's staged as such, so use addAnnexLink when adding a new file or
- modified link to git.
-}
makeGitLink :: LinkTarget -> FilePath -> Annex ()
makeGitLink linktarget file = ifM (coreSymlinks <$> Annex.getGitConfig)
( liftIO $ do
void $ tryIO $ removeFile file
createSymbolicLink linktarget file
, liftIO $ writeFile file linktarget
)
{- Creates a link on disk, and additionally stages it in git. -}
addAnnexLink :: LinkTarget -> FilePath -> Annex ()
addAnnexLink linktarget file = do
makeAnnexLink linktarget file
stageSymlink file =<< hashSymlink linktarget
{- Injects a symlink target into git, returning its Sha. -}
hashSymlink :: LinkTarget -> Annex Sha
hashSymlink linktarget = inRepo $ Git.HashObject.hashObject BlobObject $
toInternalGitPath linktarget
hashSymlink' :: Git.HashObject.HashObjectHandle -> LinkTarget -> Annex Sha
hashSymlink' h linktarget = liftIO $ Git.HashObject.hashBlob h $
toInternalGitPath linktarget
{- Stages a symlink to the annex, using a Sha of its target. -}
stageSymlink :: FilePath -> Sha -> Annex ()
stageSymlink file sha =
Annex.Queue.addUpdateIndex =<<
inRepo (Git.UpdateIndex.stageSymlink file sha)