git-annex/Git/Construct.hs
Joey Hess ed79596b75 noop
2012-04-21 23:32:33 -04:00

253 lines
7.7 KiB
Haskell

{- Construction of Git Repo objects
-
- Copyright 2010,2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.Construct (
fromCurrent,
fromCwd,
fromAbsPath,
fromPath,
fromUrl,
fromUnknown,
localToUrl,
remoteNamed,
remoteNamedFromKey,
fromRemotes,
fromRemoteLocation,
repoAbsPath,
) where
import System.Posix.User
import System.Posix.Env (getEnv, unsetEnv)
import System.Posix.Directory (changeWorkingDirectory)
import qualified Data.Map as M hiding (map, split)
import Network.URI
import Common
import Git.Types
import Git
import qualified Git.Url as Url
{- Finds the current git repository.
-
- GIT_DIR can override the location of the .git directory.
-
- When GIT_WORK_TREE is set, chdir to it, so that anything using
- this repository runs in the right location. However, this chdir is
- done after determining GIT_DIR; git does not let GIT_WORK_TREE
- influence the git directory.
-
- Both environment variables are unset, to avoid confusing other git
- commands that also look at them. This would particularly be a problem
- when GIT_DIR is relative and we chdir for GIT_WORK_TREE. Instead,
- the Git module passes --work-tree and --git-dir to git commands it runs.
-}
fromCurrent :: IO Repo
fromCurrent = do
r <- maybe fromCwd fromPath =<< getEnv "GIT_DIR"
maybe noop changeWorkingDirectory =<< getEnv "GIT_WORK_TREE"
unsetEnv "GIT_DIR"
unsetEnv "GIT_WORK_TREE"
return r
{- Finds the git repository used for the Cwd, which may be in a parent
- directory. -}
fromCwd :: IO Repo
fromCwd = getCurrentDirectory >>= seekUp isRepoTop >>= maybe norepo makerepo
where
makerepo = newFrom . Dir
norepo = error "Not in a git repository."
{- Local Repo constructor, accepts a relative or absolute path. -}
fromPath :: FilePath -> IO Repo
fromPath dir = fromAbsPath =<< absPath dir
{- Local Repo constructor, requires an absolute path to the repo be
- specified. -}
fromAbsPath :: FilePath -> IO Repo
fromAbsPath dir
| "/" `isPrefixOf` dir =
ifM (doesDirectoryExist dir') ( ret dir' , hunt )
| otherwise =
error $ "internal error, " ++ dir ++ " is not absolute"
where
ret = newFrom . Dir
{- Git always looks for "dir.git" in preference to
- to "dir", even if dir ends in a "/". -}
canondir = dropTrailingPathSeparator dir
dir' = canondir ++ ".git"
{- When dir == "foo/.git", git looks for "foo/.git/.git",
- and failing that, uses "foo" as the repository. -}
hunt
| "/.git" `isSuffixOf` canondir =
ifM (doesDirectoryExist $ dir </> ".git")
( ret dir
, ret $ takeDirectory canondir
)
| otherwise = ret dir
{- Remote Repo constructor. Throws exception on invalid url.
-
- Git is somewhat forgiving about urls to repositories, allowing
- eg spaces that are not normally allowed unescaped in urls.
-}
fromUrl :: String -> IO Repo
fromUrl url
| not (isURI url) = fromUrlStrict $ escapeURIString isUnescapedInURI url
| otherwise = fromUrlStrict url
fromUrlStrict :: String -> IO Repo
fromUrlStrict url
| startswith "file://" url = fromAbsPath $ uriPath u
| otherwise = newFrom $ Url u
where
u = fromMaybe bad $ parseURI url
bad = error $ "bad url " ++ url
{- Creates a repo that has an unknown location. -}
fromUnknown :: IO Repo
fromUnknown = newFrom Unknown
{- Converts a local Repo into a remote repo, using the reference repo
- which is assumed to be on the same host. -}
localToUrl :: Repo -> Repo -> Repo
localToUrl reference r
| not $ repoIsUrl reference = error "internal error; reference repo not url"
| repoIsUrl r = r
| otherwise = r { location = Url $ fromJust $ parseURI absurl }
where
absurl =
Url.scheme reference ++ "//" ++
Url.authority reference ++
workTree r
{- Calculates a list of a repo's configured remotes, by parsing its config. -}
fromRemotes :: Repo -> IO [Repo]
fromRemotes repo = mapM construct remotepairs
where
filterconfig f = filter f $ M.toList $ config repo
filterkeys f = filterconfig (\(k,_) -> f k)
remotepairs = filterkeys isremote
isremote k = startswith "remote." k && endswith ".url" k
construct (k,v) = remoteNamedFromKey k $ fromRemoteLocation v repo
{- Sets the name of a remote when constructing the Repo to represent it. -}
remoteNamed :: String -> IO Repo -> IO Repo
remoteNamed n constructor = do
r <- constructor
return $ r { remoteName = Just n }
{- Sets the name of a remote based on the git config key, such as
"remote.foo.url". -}
remoteNamedFromKey :: String -> IO Repo -> IO Repo
remoteNamedFromKey k = remoteNamed basename
where
basename = join "." $ reverse $ drop 1 $
reverse $ drop 1 $ split "." k
{- Constructs a new Repo for one of a Repo's remotes using a given
- location (ie, an url). -}
fromRemoteLocation :: String -> Repo -> IO Repo
fromRemoteLocation s repo = gen $ calcloc s
where
gen v
| scpstyle v = fromUrl $ scptourl v
| urlstyle v = fromUrl v
| otherwise = fromRemotePath v repo
-- insteadof config can rewrite remote location
calcloc l
| null insteadofs = l
| otherwise = replacement ++ drop (length bestvalue) l
where
replacement = drop (length prefix) $
take (length bestkey - length suffix) bestkey
(bestkey, bestvalue) = maximumBy longestvalue insteadofs
longestvalue (_, a) (_, b) = compare b a
insteadofs = filterconfig $ \(k, v) ->
startswith prefix k &&
endswith suffix k &&
startswith v l
filterconfig f = filter f $
concatMap splitconfigs $
M.toList $ fullconfig repo
splitconfigs (k, vs) = map (\v -> (k, v)) vs
(prefix, suffix) = ("url." , ".insteadof")
urlstyle v = isURI v || ":" `isInfixOf` v && "//" `isInfixOf` v
-- git remotes can be written scp style -- [user@]host:dir
scpstyle v = ":" `isInfixOf` v && not ("//" `isInfixOf` v)
scptourl v = "ssh://" ++ host ++ slash dir
where
(host, dir) = separate (== ':') v
slash d | d == "" = "/~/" ++ d
| "/" `isPrefixOf` d = d
| "~" `isPrefixOf` d = '/':d
| otherwise = "/~/" ++ d
{- Constructs a Repo from the path specified in the git remotes of
- another Repo. -}
fromRemotePath :: FilePath -> Repo -> IO Repo
fromRemotePath dir repo = do
dir' <- expandTilde dir
fromAbsPath $ workTree repo </> dir'
{- Git remotes can have a directory that is specified relative
- to the user's home directory, or that contains tilde expansions.
- This converts such a directory to an absolute path.
- Note that it has to run on the system where the remote is.
-}
repoAbsPath :: FilePath -> IO FilePath
repoAbsPath d = do
d' <- expandTilde d
h <- myHomeDir
return $ h </> d'
expandTilde :: FilePath -> IO FilePath
expandTilde = expandt True
where
expandt _ [] = return ""
expandt _ ('/':cs) = do
v <- expandt True cs
return ('/':v)
expandt True ('~':'/':cs) = do
h <- myHomeDir
return $ h </> cs
expandt True ('~':cs) = do
let (name, rest) = findname "" cs
u <- getUserEntryForName name
return $ homeDirectory u </> rest
expandt _ (c:cs) = do
v <- expandt False cs
return (c:v)
findname n [] = (n, "")
findname n (c:cs)
| c == '/' = (n, cs)
| otherwise = findname (n++[c]) cs
seekUp :: (FilePath -> IO Bool) -> FilePath -> IO (Maybe FilePath)
seekUp want dir =
ifM (want dir)
( return $ Just dir
, case parentDir dir of
"" -> return Nothing
d -> seekUp want d
)
isRepoTop :: FilePath -> IO Bool
isRepoTop dir = ifM isRepo ( return True , isBareRepo )
where
isRepo = gitSignature (".git" </> "config")
isBareRepo = ifM (doesDirectoryExist $ dir </> "objects")
( gitSignature "config" , return False )
gitSignature file = doesFileExist (dir </> file)
newFrom :: RepoLocation -> IO Repo
newFrom l = return Repo
{ location = l
, config = M.empty
, fullconfig = M.empty
, remotes = []
, remoteName = Nothing
}