From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <junkio@cox.net>
Subject: Re: [PATCH] add receive.denyNonFastforwards config variable
Date: Wed, 20 Sep 2006 15:44:06 -0700
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Cc: git@vger.kernel.org, Shawn Pearce <spearce@spearce.org>
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To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
In-Reply-To: <Pine.LNX.4.63.0609210027430.19042@wbgn013.biozentrum.uni-wuerzburg.de>
	(Johannes Schindelin's message of "Thu, 21 Sep 2006 00:28:35 +0200
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Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

> If receive.denyNonFastforwards is set to true, git-receive-pack will deny
> non fast-forwards, i.e. forced updates. Most notably, a push to a repository
> which has that flag set to true will fail.
>
> As a first user, 'git-init-db --shared' sets this flag, since in a shared
> setup, you are most unlikely to want forced pushes to succeed.

I am Ok with the general idea, but ...

> @@ -127,6 +129,16 @@ static int update(struct command *cmd)
>  		return error("unpack should have generated %s, "
>  			     "but I can't find it!", new_hex);
>  	}
> +	if (deny_non_fast_forwards) {
> +		struct commit *old_commit, *new_commit;
> +		old_commit = (struct commit *)parse_object(old_sha1);
> +		new_commit = (struct commit *)parse_object(new_sha1);
> +		struct commit_list *bases = get_merge_bases(old_commit,
> +				new_commit, 1);
> +		if (!bases || hashcmp(old_sha1, bases->item->object.sha1))
> +			return error("denying non-fast forward;"
> +					" you should pull first");
> +	}
>  	safe_create_leading_directories(lock_name);
>  
>  	newfd = open(lock_name, O_CREAT | O_EXCL | O_WRONLY, 0666);

I am wondering if there can be more than one base and the old_sha1
is not returned as the first one.