Subject: Re: [PATCH] replay: move onto NULL check before first use

From: Phillip Wood <[email-masked]>
Date: Mon, 15 Dec 2025 10:10:27 +0000

On 11/12/2025 17:56, René Scharfe wrote:
> cmd_replay() aborts if the pointer "onto" is NULL after argument
> parsing, e.g. when specifying a non-existing commit with --onto.
> 15cd4ef1f4 (replay: make atomic ref updates the default behavior,
> 2025-11-06) added code that dereferences this pointer before the check.
> Switch their places to avoid a segmentation fault.

This fixes the regression nicely. There is a preexisting bug that we 
treat an invalid --onto argument the same as a missing argument but that 
can be fixed separately.

Thanks

Phillip

> Reported-by: Kristoffer Haugsbakk <[email-masked]>
> Signed-off-by: René Scharfe <[email-masked]>
> ---
>   builtin/replay.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/builtin/replay.c b/builtin/replay.c
> index 507b909df7..64ad2f0f04 100644
> --- a/builtin/replay.c
> +++ b/builtin/replay.c
> @@ -454,6 +454,9 @@ int cmd_replay(int argc,
>   	determine_replay_mode(repo, &revs.cmdline, onto_name, &advance_name,
>   			      &onto, &update_refs);
>   
> +	if (!onto) /* FIXME: Should handle replaying down to root commit */
> +		die("Replaying down to root commit is not supported yet!");
> +
>   	/* Build reflog message */
>   	if (advance_name_opt)
>   		strbuf_addf(&reflog_msg, "replay --advance %s", advance_name_opt);
> @@ -472,9 +475,6 @@ int cmd_replay(int argc,
>   		}
>   	}
>   
> -	if (!onto) /* FIXME: Should handle replaying down to root commit */
> -		die("Replaying down to root commit is not supported yet!");
> -
>   	if (prepare_revision_walk(&revs) < 0) {
>   		ret = error(_("error preparing revisions"));
>   		goto cleanup;