Re: [PATCH] checkout: Don't crash when switching away from an invalid branch.

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Nov 7, 2008, 18:05 UTC
Message-ID: <alpine.DEB.1.00.0811071903300.30769@pacific.mpi-cbg.de>
In-Reply-To: <871vxnbhbh.fsf@wine.dyndns.org>

Hi,

On Fri, 7 Nov 2008, Alexandre Julliard wrote:

> I have a tree where for some reason HEAD was pointing to an invalid 
> commit. I'm not sure how this happened, but git checkout should be able 
> to recover from that situation without crashing.

Agree.

Show 11 quoted lines

> diff --git a/builtin-checkout.c b/builtin-checkout.c
> index 57b94d2..7c1b8cd 100644
> --- a/builtin-checkout.c
> +++ b/builtin-checkout.c
> @@ -47,7 +47,8 @@ static int post_checkout_hook(struct commit *old, struct commit *new,
>  
>  	memset(&proc, 0, sizeof(proc));
>  	argv[0] = name;
> -	argv[1] = xstrdup(sha1_to_hex(old->object.sha1));
> +	argv[1] = old ? xstrdup(sha1_to_hex(old->object.sha1))
> +		      : "0000000000000000000000000000000000000000";

I guess you want to use the variable null_sha1 here.

Show 14 quoted lines

> @@ -492,10 +493,13 @@ static void update_refs_for_switch(struct checkout_opts *opts,
>  	}
>  
>  	old_desc = old->name;
> -	if (!old_desc)
> +	if (!old_desc && old->commit)
>  		old_desc = sha1_to_hex(old->commit->object.sha1);
> -	strbuf_addf(&msg, "checkout: moving from %s to %s",
> -		    old_desc, new->name);
> +	if (old_desc)
> +		strbuf_addf(&msg, "checkout: moving from %s to %s",
> +			    old_desc, new->name);
> +	else
> +		strbuf_addf(&msg, "checkout: moving to %s", new->name);

Why not
		old_desc ? old_desc : "(invalid)"
?

> diff --git a/t/t2011-checkout-invalid-head.sh b/t/t2011-checkout-invalid-head.sh
> new file mode 100755

Nice!

Thank you, Dscho