git-annex/Annex/Link.hs
Joey Hess d7c93b8913 fully support core.symlinks=false in all relevant symlink handling code
Refactored annex link code into nice clean new library.

Audited and dealt with calls to createSymbolicLink.
Remaining calls are all safe, because:

Annex/Link.hs:  ( liftIO $ createSymbolicLink linktarget file
  only when core.symlinks=true
Assistant/WebApp/Configurators/Local.hs:                createSymbolicLink link link
  test if symlinks can be made
Command/Fix.hs: liftIO $ createSymbolicLink link file
  command only works in indirect mode
Command/FromKey.hs:     liftIO $ createSymbolicLink link file
  command only works in indirect mode
Command/Indirect.hs:                    liftIO $ createSymbolicLink l f
  refuses to run if core.symlinks=false
Init.hs:                createSymbolicLink f f2
  test if symlinks can be made
Remote/Directory.hs:    go [file] = catchBoolIO $ createSymbolicLink file f >> return True
  fast key linking; catches failure to make symlink and falls back to copy
Remote/Git.hs:          liftIO $ catchBoolIO $ createSymbolicLink loc file >> return True
  ditto
Upgrade/V1.hs:                          liftIO $ createSymbolicLink link f
  v1 repos could not be on a filesystem w/o symlinks

Audited and dealt with calls to readSymbolicLink.
Remaining calls are all safe, because:

Annex/Link.hs:		( liftIO $ catchMaybeIO $ readSymbolicLink file
  only when core.symlinks=true
Assistant/Threads/Watcher.hs:		ifM ((==) (Just link) <$> liftIO (catchMaybeIO $ readSymbolicLink file))
  code that fixes real symlinks when inotify sees them
  It's ok to not fix psdueo-symlinks.
Assistant/Threads/Watcher.hs:		mlink <- liftIO (catchMaybeIO $ readSymbolicLink file)
  ditto
Command/Fix.hs:	stopUnless ((/=) (Just link) <$> liftIO (catchMaybeIO $ readSymbolicLink file)) $ do
  command only works in indirect mode
Upgrade/V1.hs:	getsymlink = takeFileName <$> readSymbolicLink file
  v1 repos could not be on a filesystem w/o symlinks

Audited and dealt with calls to isSymbolicLink.
(Typically used with getSymbolicLinkStatus, but that is just used because
getFileStatus is not as robust; it also works on pseudolinks.)
Remaining calls are all safe, because:

Assistant/Threads/SanityChecker.hs:                             | isSymbolicLink s -> addsymlink file ms
  only handles staging of symlinks that were somehow not staged
  (might need to be updated to support pseudolinks, but this is
  only a belt-and-suspenders check anyway, and I've never seen the code run)
Command/Add.hs:         if isSymbolicLink s || not (isRegularFile s)
  avoids adding symlinks to the annex, so not relevant
Command/Indirect.hs:                            | isSymbolicLink s -> void $ flip whenAnnexed f $
  only allowed on systems that support symlinks
Command/Indirect.hs:            whenM (liftIO $ not . isSymbolicLink <$> getSymbolicLinkStatus f) $ do
  ditto
Seek.hs:notSymlink f = liftIO $ not . isSymbolicLink <$> getSymbolicLinkStatus f
  used to find unlocked files, only relevant in indirect mode
Utility/FSEvents.hs:                    | Files.isSymbolicLink s = runhook addSymlinkHook $ Just s
Utility/FSEvents.hs:                                            | Files.isSymbolicLink s ->
Utility/INotify.hs:                             | Files.isSymbolicLink s ->
Utility/INotify.hs:                     checkfiletype Files.isSymbolicLink addSymlinkHook f
Utility/Kqueue.hs:              | Files.isSymbolicLink s = callhook addSymlinkHook (Just s) change
  all above are lower-level, not relevant

Audited and dealt with calls to isSymLink.
Remaining calls are all safe, because:

Annex/Direct.hs:			| isSymLink (getmode item) =
  This is looking at git diff-tree objects, not files on disk
Command/Unused.hs:		| isSymLink (LsTree.mode l) = do
  This is looking at git ls-tree, not file on disk
Utility/FileMode.hs:isSymLink :: FileMode -> Bool
Utility/FileMode.hs:isSymLink = checkMode symbolicLinkMode
  low-level

Done!!
2013-02-17 16:43:14 -04:00

74 lines
2.4 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
{- Checks if a file is a link to a key. -}
isAnnexLink :: FilePath -> Annex (Maybe Key)
isAnnexLink file = maybe Nothing (fileKey . takeFileName) <$> getAnnexLinkTarget file
{- Gets the link target of a symlink.
-
- On a filesystem that does not support symlinks, get the link
- target by looking inside the file. (Only return at first 8k of the file,
- more than enough for any symlink target.)
-
- Returns Nothing if the file is not a symlink, or not a link to annex
- content.
-}
getAnnexLinkTarget :: FilePath -> Annex (Maybe String)
getAnnexLinkTarget file = do
v <- ifM (coreSymlinks <$> Annex.getGitConfig)
( liftIO $ catchMaybeIO $ readSymbolicLink file
, liftIO $ catchMaybeIO $ take 8192 <$> readFile file
)
case v of
Nothing -> return Nothing
Just l
| isLinkToAnnex l -> return v
| otherwise -> return Nothing
{- Creates a link on disk.
-
- On a filesystem that does not support symlinks, writes the link target
- to a file. Note that git will only treat the file as a symlink if
- it's staged as such, so use addAnnexLink when adding a new file or
- modified link to git.
-}
makeAnnexLink :: String -> FilePath -> Annex ()
makeAnnexLink linktarget file = ifM (coreSymlinks <$> Annex.getGitConfig)
( liftIO $ createSymbolicLink linktarget file
, liftIO $ writeFile file linktarget
)
{- Creates a link on disk, and additionally stages it in git. -}
addAnnexLink :: String -> FilePath -> Annex ()
addAnnexLink linktarget file = do
makeAnnexLink linktarget file
stageSymlink file =<< hashSymlink linktarget
{- Injects a symlink target into git, returning its Sha. -}
hashSymlink :: String -> Annex Sha
hashSymlink linktarget = inRepo $ Git.HashObject.hashObject BlobObject 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)