git-annex/Git/Branch.hs
Joey Hess 3802f2f270 work around lack of receive.denyCurrentBranch in direct mode
Now that direct mode sets core.bare=true, git's normal prohibition about
pushing into the currently checked out branch doesn't work.

A simple fix for this would be an update hook which blocks the pushes..
but git hooks must be executable, and git-annex needs to be usable on eg,
FAT, which lacks x bits.

Instead, enabling direct mode switches the branch (eg master) to a special
purpose branch (eg annex/direct/master). This branch is not pushed when
syncing; instead any changes that git annex sync commits get written to
master, and it's pushed (along with synced/master) to the remote.

Note that initialization has been changed to always call setDirect,
even if it's just setDirect False for indirect mode. This is needed because
if the user has just cloned a direct mode repo, that nothing has synced
with before, it may have no master branch, and only a annex/direct/master.
Resulting in that branch being checked out locally too. Calling setDirect False
for indirect mode moves back out of this branch, to a new master branch,
and ensures that a manual "git push" doesn't push changes directly to
the annex/direct/master of the remote. (It's possible that the user
makes a commit w/o using git-annex and pushes it, but nothing I can do
about that really.)

This commit was sponsored by Jonathan Harrington.
2013-11-05 21:08:31 -04:00

133 lines
3.6 KiB
Haskell

{- git branch stuff
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE BangPatterns #-}
module Git.Branch where
import Common
import Git
import Git.Sha
import Git.Command
import qualified Git.Ref
{- The currently checked out branch.
-
- In a just initialized git repo before the first commit,
- symbolic-ref will show the master branch, even though that
- branch is not created yet. So, this also looks at show-ref HEAD
- to double-check.
-}
current :: Repo -> IO (Maybe Git.Ref)
current r = do
v <- currentUnsafe r
case v of
Nothing -> return Nothing
Just branch ->
ifM (null <$> pipeReadStrict [Param "show-ref", Param $ show branch] r)
( return Nothing
, return v
)
{- The current branch, which may not really exist yet. -}
currentUnsafe :: Repo -> IO (Maybe Git.Ref)
currentUnsafe r = parse . firstLine
<$> pipeReadStrict [Param "symbolic-ref", Param $ show Git.Ref.headRef] r
where
parse l
| null l = Nothing
| otherwise = Just $ Git.Ref l
{- Checks if the second branch has any commits not present on the first
- branch. -}
changed :: Branch -> Branch -> Repo -> IO Bool
changed origbranch newbranch repo
| origbranch == newbranch = return False
| otherwise = not . null <$> diffs
where
diffs = pipeReadStrict
[ Param "log"
, Param (show origbranch ++ ".." ++ show newbranch)
, Params "--oneline -n1"
] repo
{- Given a set of refs that are all known to have commits not
- on the branch, tries to update the branch by a fast-forward.
-
- In order for that to be possible, one of the refs must contain
- every commit present in all the other refs.
-}
fastForward :: Branch -> [Ref] -> Repo -> IO Bool
fastForward _ [] _ = return True
fastForward branch (first:rest) repo =
-- First, check that the branch does not contain any
-- new commits that are not in the first ref. If it does,
-- cannot fast-forward.
ifM (changed first branch repo)
( no_ff
, maybe no_ff do_ff =<< findbest first rest
)
where
no_ff = return False
do_ff to = do
run [Param "update-ref", Param $ show branch, Param $ show to] repo
return True
findbest c [] = return $ Just c
findbest c (r:rs)
| c == r = findbest c rs
| otherwise = do
better <- changed c r repo
worse <- changed r c repo
case (better, worse) of
(True, True) -> return Nothing -- divergent fail
(True, False) -> findbest r rs -- better
(False, True) -> findbest c rs -- worse
(False, False) -> findbest c rs -- same
{- Commits the index into the specified branch (or other ref),
- with the specified parent refs, and returns the committed sha -}
commit :: String -> Branch -> [Ref] -> Repo -> IO Sha
commit message branch parentrefs repo = do
tree <- getSha "write-tree" $
pipeReadStrict [Param "write-tree"] repo
sha <- getSha "commit-tree" $ pipeWriteRead
(map Param $ ["commit-tree", show tree] ++ ps)
(Just $ flip hPutStr message) repo
update branch sha repo
return sha
where
ps = concatMap (\r -> ["-p", show r]) parentrefs
{- A leading + makes git-push force pushing a branch. -}
forcePush :: String -> String
forcePush b = "+" ++ b
{- Updates a branch (or other ref) to a new Sha. -}
update :: Branch -> Sha -> Repo -> IO ()
update branch sha = run
[ Param "update-ref"
, Param $ show branch
, Param $ show sha
]
{- Checks out a branch, creating it if necessary. -}
checkout :: Branch -> Repo -> IO ()
checkout branch = run
[ Param "checkout"
, Param "-q"
, Param "-B"
, Param $ show $ Git.Ref.base branch
]
{- Removes a branch. -}
delete :: Branch -> Repo -> IO ()
delete branch = run
[ Param "branch"
, Param "-q"
, Param "-D"
, Param $ show $ Git.Ref.base branch
]