From: Theo Buehler <tb@theobuehler.org>
Subject: Re: relayd: fix dead store
To: Rafael Sadowski <rafael@sizeofvoid.org>
Cc: Crystal Kolipe <kolipe.c@exoticsilicon.com>, tech@openbsd.org
Date: Mon, 29 Dec 2025 11:46:27 +0100

On Mon, Dec 29, 2025 at 11:39:12AM +0100, Rafael Sadowski wrote:
> On Mon Dec 29, 2025 at 11:14:43AM +0100, Theo Buehler wrote:
> > On Mon, Dec 29, 2025 at 10:44:47AM +0100, Rafael Sadowski wrote:
> > > First c is never used  so check if carp_group_find is NULL and return.
> > > 
> > > carp.c:64:7: warning: Although the value stored to 'c' is used in the
> > > enclosing expression, the value is never actually read from 'c'
> > > [deadcode.DeadSt ores]
> > >    64 |         if ((c = carp_group_find(group)) == NULL)
> > > 
> > > 
> > > diff --git a/usr.sbin/relayd/carp.c b/usr.sbin/relayd/carp.c
> > > index 6a6a55a0fbb..34b6b6785a2 100644
> > > --- a/usr.sbin/relayd/carp.c
> > > +++ b/usr.sbin/relayd/carp.c
> > > @@ -61,29 +61,31 @@ carp_demote_init(char *group, int force)
> > >  	struct carpgroup	*c;
> > >  	int			 level;
> > >  
> > > -	if ((c = carp_group_find(group)) == NULL) {
> > 
> > I would just do this and leave the rest as it is:
> > 
> > -	if ((c = carp_group_find(group)) == NULL) {
> > +	if (carp_group_find(group) == NULL) {
> > 
> > [...]
> > 
> > > +	if (carp_group_find(group) == NULL) {
> > 
> > If you do want to unindent, then you need to check for != NULL here.
> > (If a carp group is found, do nothing and succeed, otherwise create a
> > new one and add it to the carpgroups queue)
> > 
> > > +		return (0);
> > > +	}
> > 
> 
> Thanks Theo and Crystal Kolipe for your feedback. You are absolutely
> right about the NULL check, of course.
> 
> I would like to unindent. I really like this guard clause pattern, since
> the rest of the code follows this pattern as well.
> 
> diff --git a/usr.sbin/relayd/carp.c b/usr.sbin/relayd/carp.c
> index 6a6a55a0fbb..34f9c16492b 100644
> --- a/usr.sbin/relayd/carp.c
> +++ b/usr.sbin/relayd/carp.c
> @@ -61,29 +61,28 @@ carp_demote_init(char *group, int force)
>  	struct carpgroup	*c;
>  	int			 level;
>  
> -	if ((c = carp_group_find(group)) == NULL) {
> -		if ((c = calloc(1, sizeof(struct carpgroup))) == NULL) {
> -			log_warn("%s: calloc", __func__);
> -			return (-1);
> -		}
> -		if ((c->group = strdup(group)) == NULL) {
> -			log_warn("%s: strdup", __func__);
> -			free(c);
> -			return (-1);
> -		}
> -
> -		/* only demote if this group already is demoted */
> -		if ((level = carp_demote_get(group)) == -1) {
> -			free(c->group);
> -			free(c);
> -			return (-1);
> -		}
> -		if (level > 0 || force)
> -			c->do_demote = 1;
> -
> -		TAILQ_INSERT_TAIL(&carpgroups, c, entry);
> +	if (carp_group_find(group) != NULL)
> +		return (0);

Maybe move the level check up to here, then you don't need to free
stuff:

	/* only demote if this group already is demoted */
	if ((level = carp_demote_get(group)) == -1)
		return (-1);

either way, ok

> +
> +	if ((c = calloc(1, sizeof(struct carpgroup))) == NULL) {
> +		log_warn("%s: calloc", __func__);
> +		return (-1);
> +	}
> +	if ((c->group = strdup(group)) == NULL) {
> +		log_warn("%s: strdup", __func__);
> +		free(c);
> +		return (-1);
> +	}
> +	/* only demote if this group already is demoted */
> +	if ((level = carp_demote_get(group)) == -1) {
> +		free(c->group);
> +		free(c);
> +		return (-1);
>  	}
> +	if (level > 0 || force)
> +		c->do_demote = 1;
>  
> +	TAILQ_INSERT_TAIL(&carpgroups, c, entry);
>  	return (0);
>  }
>