Re: pre-rebase safety hook

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 4, 2008, 19:35 UTC
Message-ID: <7vbpvrens3.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <e1a5e9a00812040958u3af4c69ofba66567baacb79c@mail.gmail.com>

"Tim Harper" <timcharper@gmail.com> writes:

Show 10 quoted lines

> Is anyone aware of a pre-rebase hook script that will prevent (or at
> least warn) you from letting a rebase rewrite a commit that has been
> pushed or merged into any branch except it's own?
>
> I've activated the pre-rebase.sample, and it does seem to give me any
> warnings at all:
>
> Here's the terminal output demonstrating what I mean:
>
> http://pastie.org/331082

The example script starts like this:

    #!/bin/sh
    # ...
    # This sample shows how to prevent topic branches that are already
    # merged to 'next' branch from getting rebased, because allowing it
    # would result in rebasing already published history.

As it says, it explicitly checks against 'next'.

The sample was written way before "branch --with" feature was added, and I suspect what it does can be expressed more concisely in modern git.

If you want to prevent a branch whose tip commit is on more than one branches from being rebased, I think something like this would suffice.

    #!/bin/sh
    LF='
    '
    in_branches=$(git branch -a --with "${2-HEAD}")
    case "$in_branches" in
    *"$LF"*)
	: this commit is on more than two branches
        exit 1
        ;;
    esac
    exit 0

But I didn't test it.