devblog

doc/devblog/day_48__direct_mode_guard_design.mdwn

@@ -0,0 +1,29 @@
+I've been investigating ways to implement a [[/todo/direct_mode_guard]].
+Preventing a stray `git commit -a` or `git add` doing bad things in a
+direct mode repository seems increasingly important.
+
+First, considered moving `.git`, so git won't know it's a git repository.
+This doesn't seem *too* hard to do, but there will certianly be unexpected
+places that assume `.git` is the directory name.
+
+I dislike it more and more as I think about it though, because it moves
+direct mode git-annex toward being entirely separate from git, and I don't
+want to write my own version control system. Nor do I want to complicate
+the git ecosystem with tools needing to know about git-annex to work in
+such a repository.
+
+So, I'm happy that one of the other ideas I tried today seems quite
+promising. Just set core.bare=true in a direct mode repository. This nicely
+blocks all git commands that operate on the working tree from doing
+anything, which is just what's needed in direct mode, since they don't know
+how to handle the direct mode files. But it lets all git commands and other
+tools that don't touch the working tree continue to be used. You can even
+run `git log file` in such a repository (surprisingly!)
+
+It also gives an easy out for anyone who really wants to use git commands
+that operate on the work tree of their direct mode repository, by just
+passing `-c core.bare=false`. And it's really easy to implement in
+git-annex too -- it can just notice if a repo has core.bare and
+annex.direct both set, and pass that parameter to every git command it
+runs. I should be able to get by with only modifying 2 functions to
+implement this.

doc/todo/direct_mode_guard.mdwn

@@ -20,3 +20,63 @@ add`. The git wrapper could instead be another program, or it could be
 something like `git annex git add`
 
 --[[Joey]]
+
+----
+
+Or, no git wrapper could be provided. Limit the commands to only git-annex
+commands. This should be all that is needed to manage a direct mode
+repository simply, and if the user is doing something complicated that
+needs git access, they can set `GIT_DIR=.git-annex` and be careful not to
+shoot off their foot. (Or can just switch to indirect mode!)
+
+This wins on simplicity, and if it's the wrong choice a git wrapper
+can be added later. --[[Joey]]
+
+---
+
+Implementation: Pretty simple really. Already did the hard lifting to
+support `GIT_DIR`, so only need to override the default git directory
+in direct mode when that's not set to `.git-annex`.
+
+A few things hardcode ".git", including Assistant.Threads.Watcher.ignored
+and `Seek.withPathContents`, and parts of `Git.Construct`.
+
+---
+
+Transition: git-annex should detect when it's in a direct mode repository
+with a .git directory and no .git-annex directory, and transparently
+do the move to transition to the new scheme. (And remember that `git annex
+indirect` needs to move it back.)
+
+# alternative approach: move index
+
+Rather than moving .git, maybe move .git/index?
+
+This would cause git to think that all files in the tree were deleted.
+So git commit -a would make a commit that removes them from git history.
+But, the files in the work tree are not touched by this.
+
+Also, git checkout, git merge, and other things that manipulate the work
+tree refuse to do anything if they'd change a file that they think is
+untracked.
+
+Hmm, this does't solve the user accidentially running git add on an annexed
+file; the whole file still gets added.
+
+# alternative approach: fake bare repo
+
+Set core.bare to true.  This prevents all work tree operations, 
+so prevents any foot shooting. It still lets the user run commands like
+git log, even on files in the tree, and git fetch, and push, and git
+config, etc.
+
+Even better, it integrates with other tools, like `mr`, so they know
+it's a git repo.
+
+This seems really promising. But of course, git-annex has its own set of
+behaviors in a bare repo, so will need to recognise that this repo is not
+really bare, and avoid them.
+
+(Git may also have some bare repo behaviors that are unwanted. One example
+is that git allows pushes to the current branch in a bare repo, 
+even when `receive.denyCurrentBranch` is set.)