add mktree interface

Git/LsTree.hs

@@ -8,9 +8,10 @@
 module Git.LsTree (
 	TreeItem(..),
 	lsTree,
+	lsTree',
 	lsTreeParams,
 	lsTreeFiles,
-	parseLsTree
+	parseLsTree,
 ) where
 
 import Common
@@ -33,8 +34,11 @@ data TreeItem = TreeItem
 {- Lists the complete contents of a tree, recursing into sub-trees,
  - with lazy output. -}
 lsTree :: Ref -> Repo -> IO ([TreeItem], IO Bool)
-lsTree t repo = do
-	(l, cleanup) <- pipeNullSplit (lsTreeParams t []) repo
+lsTree = lsTree' []
+
+lsTree' :: [CommandParam] -> Ref -> Repo -> IO ([TreeItem], IO Bool)
+lsTree' ps t repo = do
+	(l, cleanup) <- pipeNullSplit (lsTreeParams t ps) repo
 	return (map parseLsTree l, cleanup)
 
 lsTreeParams :: Ref -> [CommandParam] -> [CommandParam]

Git/Tree.hs

@@ -0,0 +1,105 @@
+{- git trees
+ -
+ - Copyright 2016 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Git.Tree (
+	Tree(..),
+	TreeContent(..),
+	getTree,
+	recordTree,
+) where
+
+import Common
+import Git
+import Git.FilePath
+import Git.Types
+import Git.Command
+import qualified Git.LsTree as LsTree
+import qualified Utility.CoProcess as CoProcess
+
+import Numeric
+import System.Posix.Types
+
+newtype Tree = Tree [TreeContent]
+	deriving (Show)
+
+data TreeContent
+	= TreeBlob TopFilePath FileMode Sha
+	-- A subtree that is already recorded in git, with a known sha.
+	| RecordedSubTree TopFilePath Sha [TreeContent]
+	-- A subtree that has not yet been recorded in git.
+	| NewSubTree TopFilePath [TreeContent]
+	deriving (Show)
+
+{- Gets the Tree for a Ref. -}
+getTree :: Ref -> Repo -> IO (Tree, IO Bool)
+getTree r repo = do
+	-- Pass -t to get the tree object shas, which are normally omitted.
+	(l, cleanup) <- LsTree.lsTree' [Param "-t"] r repo
+	let t = either (\e -> error ("ls-tree parse error:" ++ e)) id (extractTree l)
+	return (t, cleanup)
+
+extractTree :: [LsTree.TreeItem] -> Either String Tree
+extractTree l = case go [] "" l of
+	Right (t, []) -> Right (Tree t)
+	Right _ -> parseerr "unexpected tree form"
+	Left e -> parseerr e
+  where
+	go t _ [] = Right (t, [])
+	go t prefix (i:is)
+		| prefix `isPrefixOf` getTopFilePath (LsTree.file i) = 
+			case readObjectType (LsTree.typeobj i) of
+				Just BlobObject ->
+					let b = TreeBlob (LsTree.file i) (LsTree.mode i) (LsTree.sha i)
+					in go (b:t) prefix is
+				Just TreeObject -> case go [] (getTopFilePath (LsTree.file i) ++ "/") is of
+					Right (subtree, is') ->
+						let st = RecordedSubTree (LsTree.file i) (LsTree.sha i) subtree
+						in go (st:t) prefix is'
+					Left e -> Left e
+				_ -> parseerr ("unexpected object type \"" ++ LsTree.typeobj i ++ "\"")
+		| otherwise = Right (t, i:is)
+	parseerr = Left
+
+{- Records a Tree in the Repo, returning its Sha.
+ - 
+ - Efficiently handles subtrees, by only recording ones that have not
+ - already been recorded before. And even when many subtrees need to be
+ - recorded, it's done with a single call to git mktree, using its batch
+ - interface.
+ -}
+recordTree :: Repo -> Tree -> IO Sha
+recordTree repo (Tree t) = do
+	h <- CoProcess.rawMode =<< gitCoProcessStart False ps repo
+	sha <- recordTree' h t
+	CoProcess.stop h
+	return sha
+  where
+	ps = [Param "mktree", Param "--batch", Param "-z"]
+
+recordTree' :: CoProcess.CoProcessHandle -> [TreeContent] -> IO Sha
+recordTree' h l = mkTree h =<< mapM (recordSubTree h) l
+
+recordSubTree :: CoProcess.CoProcessHandle -> TreeContent -> IO TreeContent
+recordSubTree h (NewSubTree d l) = do
+	l' <- mapM (recordSubTree h) l
+	sha <- mkTree h l'
+	return (RecordedSubTree d sha l')
+recordSubTree _ alreadyrecorded = return alreadyrecorded
+ 
+mkTree :: CoProcess.CoProcessHandle -> [TreeContent] -> IO Sha
+mkTree cp l = CoProcess.query cp send receive
+  where
+	send h = do
+		forM_ l $ \i -> hPutStr h $ case i of
+			TreeBlob f fm s -> mkTreeOutput fm BlobObject s f
+			RecordedSubTree f s _ -> mkTreeOutput 0o040000 TreeObject s f
+			NewSubTree _ _ -> error "recordSubTree internal error; unexpected NewSubTree"
+		hPutStr h "\NUL" -- signal end of tree to --batch
+	receive h = Ref <$> hGetLine h
+
+mkTreeOutput :: FileMode -> ObjectType -> Sha -> TopFilePath -> String
+mkTreeOutput fm ot s f = showOct fm "" ++ " " ++ show ot ++ " " ++ fromRef s ++ "\t" ++ takeFileName (getTopFilePath f) ++ "\NUL"