support direct mode repositories with core.bare=true (not yet default)

Direct mode repositories can now have core.bare=true set, to prevent
accidentally running git commands that try to operate on the work tree,
and so do the wrong thing.

This is not yet the default, and it causes known problems for git-annex sync
due to receive.denyCurrentBranch not working in bare repositories.

This commit was sponsored by Richard Hartmann.

Annex.hs

@@ -12,7 +12,6 @@ module Annex (
 	AnnexState(..),
 	PreferredContentMap,
 	new,
-	newState,
 	run,
 	eval,
 	getState,
@@ -41,6 +40,7 @@ import Control.Concurrent
 import Common
 import qualified Git
 import qualified Git.Config
+import Git.Types hiding (remotes)
 import Git.CatFile
 import Git.CheckAttr
 import Git.CheckIgnore
@@ -112,9 +112,9 @@ data AnnexState = AnnexState
 	}
 
 newState :: Git.Repo -> AnnexState
-newState gitrepo = AnnexState
-	{ repo = gitrepo
-	, gitconfig = extractGitConfig gitrepo
+newState r = AnnexState
+	{ repo = if annexDirect c then fixupDirect r else r
+	, gitconfig = c
 	, backends = []
 	, remotes = []
 	, output = defaultMessageState
@@ -144,6 +144,8 @@ newState gitrepo = AnnexState
 	, inodeschanged = Nothing
 	, useragent = Nothing
 	}
+  where
+  	c = extractGitConfig r
 
 {- Makes an Annex state object for the specified git repo.
  - Ensures the config is read, if it was not already. -}
@@ -247,3 +249,13 @@ withCurrentState :: Annex a -> Annex (IO a)
 withCurrentState a = do
 	s <- getState id
 	return $ eval s a
+
+{- Direct mode repos have core.bare=true, but are not really bare.
+ - Fix up the Repo to be a non-bare repo, and arrange for git commands
+ - run by git-annex to be passed parameters that override this setting. -}
+fixupDirect :: Git.Repo -> Git.Repo
+fixupDirect r@(Repo { location = Local { gitdir = d, worktree = Nothing } }) = r
+	{ location = Local { gitdir = d </> ".git", worktree = Just d }
+	, gitGlobalOpts = gitGlobalOpts r ++ [Param "-c", Param "core.bare=false"]
+	}
+fixupDirect r = r

debian/changelog

@@ -1,5 +1,10 @@
 git-annex (4.20131102) UNRELEASED; urgency=low
 
+  * Direct mode repositories can now have core.bare=true set, to prevent
+    accidentally running git commands that try to operate on the work tree,
+    and so do the wrong thing.
+  * The -c option now not only modifies the git configuration seen by
+    git-annex, but it is passed along to every git command git-annex runs.
   * Improve local pairing behavior when two computers both try to start
     the pairing process separately.
   * sync: Work even when the local git repository is new and empty,
@@ -12,8 +17,6 @@ git-annex (4.20131102) UNRELEASED; urgency=low
   * Fix zombie process that occurred when switching between repository
     views in the webapp.
   * map: Work when there are gcrypt remotes.
-  * The -c option now not only modifies the git configuration seen by
-    git-annex, but it is passed along to every git command git-annex runs.
 
  -- Joey Hess <joeyh@debian.org>  Sat, 02 Nov 2013 14:54:36 -0400
 

doc/direct_mode.mdwn

@@ -4,8 +4,7 @@ git, and in turn point at the content of large files that is stored in
 
 The advantage of direct mode is that you can access files directly,
 including modifying them. The disadvantage is that most regular git
-commands cannot safely be used, and only a subset of git-annex commands
-can be used.
+commands cannot be used in a direct mode repository.
 
 Normally, git-annex repositories start off in indirect mode. With some
 exceptions:
@@ -21,7 +20,7 @@ exceptions:
 Any repository can be converted to use direct mode at any time, and if you
 decide not to use it, you can convert back to indirect mode just as easily.
 Also, you can have one clone of a repository using direct mode, and another
-using indirect mode; direct mode interoperates.
+using indirect mode.
 
 To start using direct mode:
 
@@ -52,7 +51,6 @@ computers, and manage your files, this should not be a concern for you.
 ## use a direct mode repository
 
 You can use most git-annex commands as usual in a direct mode repository.
-A very few commands don't work in direct mode, and will refuse to do anything.
 
 Direct mode also works well with the git-annex assistant.
 
@@ -63,23 +61,32 @@ the changes to other repositories for `git annex sync` there to pick up,
 and will pull and merge any changes made on other repositories into the
 local repository.
 
-While you generally will just use `git annex sync`, if you want to,
-you can use `git commit --staged`, or plain `git commit`.
-But not `git commit -a`, or `git commit <file>` ..
-that'd commit whole large files into git!
-
 ## what doesn't work in direct mode
 
-`git annex status` shows incomplete information. A few other commands,
-like `git annex unlock` don't make sense in direct mode and will refuse to
-run.
+A very few git-annex commands don't work in direct mode, and will refuse
+to do anything. For example, `git annex unlock` doesn't make sense in
+direct mode.
 
-As for git commands, you can probably use some git working tree
-manipulation commands, like `git checkout` and `git revert` in useful
-ways... But beware, these commands can replace files that are present in
-your repository with broken symlinks. If that file was the only copy you
-had of something, it'll be lost. 
+As for git commands, direct mode prevents using any git command that would
+modify or access the work tree. So you cannot `git commit` or `git pull`
+(use `git annex sync` for both instead), or run `git status`.
+These git commands will complain "fatal: This operation must be run in a work tree".
 
-This is one more reason it's wise to make git-annex untrust your direct mode
-repositories. Still, you can lose data using these sort of git commands, so
-use extreme caution.
+The reason for this is that git doesn't understand how git-annex uses the
+work tree in direct mode. Where git expects the symlinks that get checked
+into git to be checked out in the work tree, direct mode instead replaces
+them with the actual content of files, as managed by git-annex.
+
+There are still lots of git commands you can use in direct mode. For
+example, you can run `git log` on files, run `git push`, `git config`,
+`git remote add` etc.
+
+## forcing git to use the work tree in direct mode
+
+This is for experts only. You can lose data doing this, or check enormous
+files directly into your git repository, and it's your fault if you do!
+Also, there should be no good reason to need to do this, ever.
+
+Ok, with the warnings out of the way, all you need to do to make any
+git command access the work tree in direct mode is pass it 
+`-c core.bare=false`