threads / discuss / 3485

someone changed the contents of my HEAD.

Subject: someone changed the contents of my HEAD.

## tl;dr

3 messages between Feb 28, 2006 and Feb 28, 2006.

replies: 2people: 2as markdown or json

Dave Jones· Feb 28, 2006, 03:04 UTC · lore

I just tried to check in some changes to some trees on master.kernel.org, and found after the first checkin that git claimed..

fatal: Not a git repository

A lot of head-scratching later, I think I've figured out what's happened. It seems there was a recent upgrade to the version of git on m.k.o, which is incompatible with the helper scripts I used before.

When checking in changes previously, I used this..

#!/bin/sh export GIT_AUTHOR_NAME="$1" export GIT_AUTHOR_EMAIL="$2" tree=$(git-write-tree) || exit 1 commit=$(git-commit-tree $tree -p HEAD) || exit 1 echo $commit > .git/HEAD

and called it thus..

commit-as "Dave Jones" "<davej@redhat.com>"

Previously, this updated .git/HEAD to a ptr to the latest committed change. All was well, as I only ever have one HEAD in my trees.

With the new .git however, when I clone a new tree, .git/HEAD contains ref: refs/heads/master, so my script destroys the git metadata.

For my newly created repos, this isn't a problem, as I can fudge my commit-as script to write to .git/refs/heads/master instead, but my concern now is the unpulled changes in the existing repos I have on master. Will Linus be able to pull those into his tree with git 1.2.3, or will I have to recreate those repos with the new-style .git/HEAD ?

		Dave

Junio C Hamano· Feb 28, 2006, 05:22 UTC · re: Dave Jones · lore

Re: someone changed the contents of my HEAD.

Dave Jones <davej@redhat.com> writes:

Show 8 quoted lines

> When checking in changes previously, I used this..
>
> #!/bin/sh
> export GIT_AUTHOR_NAME="$1"
> export GIT_AUTHOR_EMAIL="$2"
> tree=$(git-write-tree) || exit 1
> commit=$(git-commit-tree $tree -p HEAD) || exit 1
> echo $commit > .git/HEAD

This has been deprecated for a looong time, but perhaps I should have been louder. "git commit --author" should be fine -- I do not think you do not even need such a wrapper.

Show 6 quoted lines

> For my newly created repos, this isn't a problem, as I can fudge my
> commit-as script to write to .git/refs/heads/master instead, but
> my concern now is the unpulled changes in the existing repos
> I have on master.  Will Linus be able to pull those into his tree
> with git 1.2.3, or will I have to recreate those repos with the
> new-style .git/HEAD ?

A .git/HEAD symlink pointing at refs/heads/master _is_ still (and will be) supported, so either symlink or symref is fine. Bare SHA1 object name in HEAD is not -- git would not know which branch you are on, so "checkin" would not work after that.

Your refs/heads/master might be stale (one rev or more older than what you replaced .git/HEAD with) but still should be a proper ancestor. After making sure your refs/heads/master has the right commit (you may have it there already if you have been updating them using "git-push"), running "git-symbolic-ref HEAD refs/heads/master" would fix things.

Dave Jones· Feb 28, 2006, 05:58 UTC · re: Junio C Hamano · lore

Re: someone changed the contents of my HEAD.

On Mon, Feb 27, 2006 at 09:22:18PM -0800, Junio C Hamano wrote:
 > > #!/bin/sh
 > > export GIT_AUTHOR_NAME="$1"
 > > export GIT_AUTHOR_EMAIL="$2"
 > > tree=$(git-write-tree) || exit 1
 > > commit=$(git-commit-tree $tree -p HEAD) || exit 1
 > > echo $commit > .git/HEAD
 > 
 > This has been deprecated for a looong time, but perhaps I should
 > have been louder.  "git commit --author" should be fine -- I do
 > not think you do not even need such a wrapper.

I guess I wasn't paying attention :) It's worked just fine up until a few days ago. I can change my habits to use the preferred approach though.

 > > For my newly created repos, this isn't a problem, as I can fudge my
 > > commit-as script to write to .git/refs/heads/master instead, but
 > > my concern now is the unpulled changes in the existing repos
 > > I have on master.  Will Linus be able to pull those into his tree
 > > with git 1.2.3, or will I have to recreate those repos with the
 > > new-style .git/HEAD ?
 >
 > A .git/HEAD symlink pointing at refs/heads/master _is_ still
 > (and will be) supported, so either symlink or symref is fine.
 > Bare SHA1 object name in HEAD is not -- git would not know which
 > branch you are on, so "checkin" would not work after that.
 > 
 > Your refs/heads/master might be stale (one rev or more older
 > than what you replaced .git/HEAD with) but still should be a
 > proper ancestor.  After making sure your refs/heads/master has
 > the right commit (you may have it there already if you have been
 > updating them using "git-push"), running "git-symbolic-ref HEAD
 > refs/heads/master" would fix things.

One scary thing fell out of this. Andrew did a pull on my trees and found bogons in both of them. Both agpgart and cpufreq trees contained partial (1 file) reverts of earlier commits in my last commit to the head of each repo. I can't explain how that happened, and I'm surprised my head-munging would be the reason.

I've just rebuilt those two repos as there was only 3-4 patches in both, so it wasn't a big deal. Something to watch out for though if anyone else has been doing something similar to how I was doing checkins.

		Dave