git-annex/Git/DiffTree.hs
Joey Hess d6711800ad avoid bad commits after interrupted direct mode sync (or merge)
It was possible for a interrupted sync or merge in direct mode to
leave the work tree out of sync with the last recorded commit.
This would result in the next commit seeing files missing from the work
tree, and committing their removal.

Now, a direct mode merge happens not only in a throwaway work tree, but using
a temporary index file, and without any commits or index changes
being made until the real work tree has been updated. If the merge is
interrupted, the work tree may have some updated files, but worst case a
commit will redundantly commit changes that come from the merge.

This commit was sponsored by Tony Cantor.
2014-06-09 19:40:28 -04:00

102 lines
3 KiB
Haskell

{- git diff-tree interface
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.DiffTree (
DiffTreeItem(..),
diffTree,
diffTreeRecursive,
diffIndex,
diffWorkTree,
) where
import Numeric
import System.Posix.Types
import Common
import Git
import Git.Sha
import Git.Command
import Git.FilePath
import qualified Git.Filename
import qualified Git.Ref
data DiffTreeItem = DiffTreeItem
{ srcmode :: FileMode
, dstmode :: FileMode
, srcsha :: Sha -- nullSha if file was added
, dstsha :: Sha -- nullSha if file was deleted
, status :: String
, file :: TopFilePath
} deriving Show
{- Diffs two tree Refs. -}
diffTree :: Ref -> Ref -> Repo -> IO ([DiffTreeItem], IO Bool)
diffTree src dst = getdiff (Param "diff-tree")
[Param (fromRef src), Param (fromRef dst)]
{- Diffs two tree Refs, recursing into sub-trees -}
diffTreeRecursive :: Ref -> Ref -> Repo -> IO ([DiffTreeItem], IO Bool)
diffTreeRecursive src dst = getdiff (Param "diff-tree")
[Param "-r", Param (fromRef src), Param (fromRef dst)]
{- Diffs between a tree and the index. Does nothing if there is not yet a
- commit in the repository. -}
diffIndex :: Ref -> Repo -> IO ([DiffTreeItem], IO Bool)
diffIndex ref = diffIndex' ref [Param "--cached"]
{- Diffs between a tree and the working tree. Does nothing if there is not
- yet a commit in the repository, or if the repository is bare. -}
diffWorkTree :: Ref -> Repo -> IO ([DiffTreeItem], IO Bool)
diffWorkTree ref repo =
ifM (Git.Ref.headExists repo)
( diffIndex' ref [] repo
, return ([], return True)
)
diffIndex' :: Ref -> [CommandParam] -> Repo -> IO ([DiffTreeItem], IO Bool)
diffIndex' ref params repo =
ifM (Git.Ref.headExists repo)
( getdiff (Param "diff-index")
( params ++ [Param $ fromRef ref] )
repo
, return ([], return True)
)
getdiff :: CommandParam -> [CommandParam] -> Repo -> IO ([DiffTreeItem], IO Bool)
getdiff command params repo = do
(diff, cleanup) <- pipeNullSplit ps repo
return (parseDiffTree diff, cleanup)
where
ps = command : Params "-z --raw --no-renames -l0" : params
{- Parses diff-tree output. -}
parseDiffTree :: [String] -> [DiffTreeItem]
parseDiffTree l = go l []
where
go [] c = c
go (info:f:rest) c = go rest (mk info f : c)
go (s:[]) _ = error $ "diff-tree parse error " ++ s
mk info f = DiffTreeItem
{ srcmode = readmode srcm
, dstmode = readmode dstm
, srcsha = fromMaybe (error "bad srcsha") $ extractSha ssha
, dstsha = fromMaybe (error "bad dstsha") $ extractSha dsha
, status = s
, file = asTopFilePath $ fromInternalGitPath $ Git.Filename.decode f
}
where
readmode = fst . Prelude.head . readOct
-- info = :<srcmode> SP <dstmode> SP <srcsha> SP <dstsha> SP <status>
-- All fields are fixed, so we can pull them out of
-- specific positions in the line.
(srcm, past_srcm) = splitAt 7 $ drop 1 info
(dstm, past_dstm) = splitAt 7 past_srcm
(ssha, past_ssha) = splitAt shaSize past_dstm
(dsha, past_dsha) = splitAt shaSize $ drop 1 past_ssha
s = drop 1 past_dsha