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|
{- git-union-merge program
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
import System.Environment
import System.FilePath
import System.Directory
import System.Cmd.Utils
import System.Posix.Env (setEnv)
import Control.Monad (when)
import Data.List
import Data.Maybe
import Data.String.Utils
import qualified GitRepo as Git
import Utility
header :: String
header = "Usage: git-union-merge branch ref ref"
usage :: IO a
usage = error $ "bad parameters\n\n" ++ header
main :: IO ()
main = do
[branch, aref, bref] <- parseArgs
g <- setup
stage g aref bref
commit g branch aref bref
cleanup g
parseArgs :: IO [String]
parseArgs = do
args <- getArgs
if (length args /= 3)
then usage
else return args
tmpIndex :: Git.Repo -> FilePath
tmpIndex g = Git.workTree g </> Git.gitDir g </> "index.git-union-merge"
{- Configures git to use a temporary index file. -}
setup :: IO Git.Repo
setup = do
g <- Git.configRead =<< Git.repoFromCwd
cleanup g -- idempotency
setEnv "GIT_INDEX_FILE" (tmpIndex g) True
return g
cleanup :: Git.Repo -> IO ()
cleanup g = do
e' <- doesFileExist (tmpIndex g)
when e' $ removeFile (tmpIndex g)
{- Stages the content of both refs into the index. -}
stage :: Git.Repo -> String -> String -> IO ()
stage g aref bref = do
-- Get the contents of aref, as a starting point.
ls <- fromgit
["ls-tree", "-z", "-r", "--full-tree", aref]
-- Identify files that are different between aref and bref, and
-- inject merged versions into git.
diff <- fromgit
["diff-tree", "--raw", "-z", "-r", "--no-renames", "-l0", aref, bref]
ls' <- mapM mergefile (pairs diff)
-- Populate the index file. Later lines override earlier ones.
togit ["update-index", "-z", "--index-info"]
(join "\0" $ ls++catMaybes ls')
where
fromgit l = Git.pipeNullSplit g (map Param l)
togit l content = Git.pipeWrite g (map Param l) content
>>= forceSuccess
tofromgit l content = do
(h, s) <- Git.pipeWriteRead g (map Param l) content
length s `seq` do
forceSuccess h
Git.reap
return ((), s)
pairs [] = []
pairs (_:[]) = error "parse error"
pairs (a:b:rest) = (a,b):pairs rest
nullsha = take shaSize $ repeat '0'
ls_tree_line sha file = "100644 blob " ++ sha ++ "\t" ++ file
unionmerge = unlines . nub . lines
mergefile (info, file) = do
let [_colonamode, _bmode, asha, bsha, _status] = words info
if bsha == nullsha
then return Nothing -- already staged from aref
else mergefile' file asha bsha
mergefile' file asha bsha = do
let shas = filter (/= nullsha) [asha, bsha]
content <- Git.pipeRead g $ map Param ("show":shas)
sha <- getSha "hash-object" $
tofromgit ["hash-object", "-w", "--stdin"] $
unionmerge content
return $ Just $ ls_tree_line sha file
{- Commits the index into the specified branch. -}
commit :: Git.Repo -> String -> String -> String -> IO ()
commit g branch aref bref = do
tree <- getSha "write-tree" $
pipeFrom "git" ["write-tree"]
sha <- getSha "commit-tree" $
pipeBoth "git" ["commit-tree", tree, "-p", aref, "-p", bref]
"union merge"
Git.run g "update-ref" [Param $ "refs/heads/" ++ branch, Param sha]
{- Runs an action that causes a git subcommand to emit a sha, and strips
any trailing newline, returning the sha. -}
getSha :: String -> IO (a, String) -> IO String
getSha subcommand a = do
(_, t) <- a
let t' = if last t == '\n'
then take (length t - 1) t
else t
when (length t' /= shaSize) $
error $ "failed to read sha from git " ++ subcommand ++ " (" ++ t' ++ ")"
return t'
shaSize :: Int
shaSize = 40
|
