git-annex/Git/Index.hs
Joey Hess 1b6cbb63e9
still can't express custom-setup deps
They need unix on non-windows, for Utility.Env, which Build.Configure uses,
but cabal can't express that in a custom-setup stanza.

To avoid this problem, Utility.Env would need to be moved into
unix-compat..
2017-11-14 14:59:51 -04:00

70 lines
2 KiB
Haskell

{- git index file stuff
-
- Copyright 2011 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.Index where
import Common
import Git
import Utility.Env
indexEnv :: String
indexEnv = "GIT_INDEX_FILE"
{- Gets value to set GIT_INDEX_FILE to. Input should be absolute path,
- or relative to the CWD.
-
- When relative, GIT_INDEX_FILE is interpreted by git as being
- relative to the top of the work tree of the git repository,
- not to the CWD. Worse, other environment variables (GIT_WORK_TREE)
- or git options (--work-tree) or configuration (core.worktree)
- can change what the relative path is interpreted relative to.
-
- So, an absolute path is the only safe option for this to return.
-}
indexEnvVal :: FilePath -> IO String
indexEnvVal = absPath
{- Forces git to use the specified index file.
-
- Returns an action that will reset back to the default
- index file.
-
- Warning: Not thread safe.
-}
override :: FilePath -> Repo -> IO (IO ())
override index _r = do
res <- getEnv var
val <- indexEnvVal index
setEnv var val True
return $ reset res
where
var = "GIT_INDEX_FILE"
reset (Just v) = setEnv indexEnv v True
reset _ = unsetEnv var
indexFile :: Repo -> FilePath
indexFile r = localGitDir r </> "index"
{- Git locks the index by creating this file. -}
indexFileLock :: Repo -> FilePath
indexFileLock r = indexFile r ++ ".lock"
{- When the pre-commit hook is run, and git commit has been run with
- a file or files specified to commit, rather than committing the staged
- index, git provides the pre-commit hook with a "false index file".
-
- Changes made to this index will influence the commit, but won't
- affect the real index file.
-
- This detects when we're in this situation, using a heuristic, which
- might be broken by changes to git. Any use of this should have a test
- case to make sure it works.
-}
haveFalseIndex :: IO Bool
haveFalseIndex = maybe (False) check <$> getEnv indexEnv
where
check f = "next-index" `isPrefixOf` takeFileName f