Git for Plan 9: git/fs

All commits in this repository were made with git9 running on 9front.

About

Plan 9 is a non-posix system. Upstream git has been ported, but feels distinctly un-plan9ish, and even in its native environment, has been justifiably tarred and feathered for its user experience.

Git/fs implements a git client for plan 9. The intent is to support working with git repositories, without cloning the git interface directly.

Git/fs is my daily driver. It's solid, and works well for my needs.

Getting Started

** USE THE VERSION THAT COMES WITH 9FRONT **

The version that comes with 9front is the most up to date version out there. If you are on 9front, you do not need this repository.

If you are NOT on 9front:

Install the appropriate patches to your system (listed below), then:

Get a bootstrap copy:

% cd /tmp
% hget https://orib.dev/git/git9/HEAD/snap.tar.gz | tar xvz
% cd git9
% mk all
% mk install

Then get an updatable version from git:

% cd $home/src
% git/clone gits://orib.dev/git9
% cd git9
% mk all
% mk install

Configure your user name and email:

% mkdir -p $home/lib/git
% echo '
[user]
	name=Ori Bernstein
	[email protected]
' > $home/lib/git/config

Read the docs:

% man 1 git
% man 4 gitfs

And start committing!

Structure

The git/fs program provides a file system mounted on $repo/.git/fs. It provides a read-only view into the repository contents to allow scripts to inspect the data. Surrounding scripts and binaries will manipulate the repository contents directly. These changes will be immediately mirrored in the file system.

Scripts will generally mount git/fs as needed to do their work, but if you want to browse the repository manually, run it yourself. You'll get $repo/.git/fs mounted, with the following contents:

$repo/.git/fs/object:	The objects in the repo.
$repo/.git/fs/branch:	The branches in the repo.
$repo/.git/fs/ctl:		A file showing the status of the repo.
			Currently, it only shows the current branch.
$repo/.git/fs/HEAD		An alias for the currently checked out
			commit directory.

Visible Differences

The most obvious difference is that Git's index is a bit boneheaded, so I'm ignoring it. The index doesn't affect the wire protocol, so this isn't an interoperability issue, unless you share the same physical repository on both Plan 9 and Unix. If you do, expect them to disagree about the files that have been modified in the working copy.

In fact, the entire concept of the staging area has been dropped, as it's both confusing and clunky. There are now only three states that files can be in: 'untracked', 'dirty', and 'committed'. Tracking is done with empty files under .git/index9/{removed,tracked}/path/to/file.

It's implemented in Plan 9 flavor C, and provides tools for writing repository contents, and a file system for read-only access, which will mirror the current state of the repository.

Installation

Install with mk install.

Examples

Some usage examples:

git/clone git://git.eigenstate.org/ori/mc.git
git/log
cd subdir/name
git/add foo.c
diff bar.c $repo/.git/fs/HEAD/
git/commit foo.c
git/push

Commits are presented as directories with the following contents:

author:	A file containing the author name
hash:	A file containing the commit hash
parent:	A file containing the commit parents, one per line.
msg:	A file containing the log message for that commit
tree:	A directory containing a view of the repository.

So, for example:

% ls $repo/.git/fs/branch/heads/master
$repo/.git/fs/branch/heads/master/author
$repo/.git/fs/branch/heads/master/hash
$repo/.git/fs/branch/heads/master/msg
$repo/.git/fs/branch/heads/master/parent
$repo/.git/fs/branch/heads/master/tree
% cat $repo/.git/fs/branch/heads/master/hash
7d539a7c08aba3f31b3913e0efef11c43ea9

# This is the same commit, with the same contents.
% ls $repo/.git/fs/object/7d539a7c08aba3f31b3913e0efef11c43ea9f9ef
$repo/.git/fs/object/7d539a7c08aba3f31b3913e0efef11c43ea9f9ef/author
$repo/.git/fs/object/7d539a7c08aba3f31b3913e0efef11c43ea9f9ef/hash
$repo/.git/fs/object/7d539a7c08aba3f31b3913e0efef11c43ea9f9ef/msg
$repo/.git/fs/object/7d539a7c08aba3f31b3913e0efef11c43ea9f9ef/parent
$repo/.git/fs/object/7d539a7c08aba3f31b3913e0efef11c43ea9f9ef/tree

# what git/diff will hopefully do more concisely soon, filtering
# out the non-git files.
ape/diff -ur $repo/.git/fs/branch/heads/master/tree .
Only in .: .git
Only in .: debug
diff -ur $repo/.git/fs/branch/heads/master/tree/fold.myr ./fold.myr
--- $repo/.git/fs/branch/heads/master/tree/fold.myr	Wed Dec 31 16:00:00 1969
+++ ./fold.myr	Mon Apr  1 21:39:06 2019
@@ -6,6 +6,8 @@
 	const foldexpr : (e : expr# -> std.option(constval))
 ;;
 
+/* Look, diffing files just works, and I don't need any fancy glue! */
+
 const foldexpr = {e
 	match e
 	| &(`Eident &[.sc=`Sclassenum, .name=name, .ty=`Tyenum &(`Body enum)]):
Only in .: refs

The following utilities and binaries are provided:

fs:	The git filesystem.
fetch:	The protocol bits for getting data from a git server.
send:	The protocol bits for sending data to a git server.
save:	The gnarly bits for storing the files for a commit.
conf:	A program to extract information from a config file.
clone:	Clones a repository.
commit:	Commits a snapshot of the selected files.
log:	Prints the contents of a commmit log.
add:	Tells the repository to add a file to the next commit.
walk:	`du`, but for git status.
...	and more

Supported protocols: git:// and git+ssh://. If someone implements others, I'll gladly accept patches.

9legacy Notes

To use git9 on 9legacy, these patches are necessary.

- rc-line-split: implement delim{...} syntax for rc
- walk: port walk command to 9legacy.
- aux/getflags: 9front updated it with support for named args

Additionally, git9 defaults to editing with hold(1). This command is not present on 9legacy. Import it, or set $editor to your choice of editor.