Re: [PATCH ipvsadm 2/5] ipvsadm: fix ambiguous usage error message

[Jeremy Sowden <azazel@debian.org>]

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On 2025-01-12, at 23:18:43 +0200, Julian Anastasov wrote:
> On Sun, 12 Jan 2025, Jeremy Sowden wrote:
> > If `-6` is used without `-f`, the usage error message is "-6 used before -f",
> > which can be misconstrued as warning that both options were used but in the
> > wrong order.
> > 
> > Change the option-parsing to allow `-6` to appear before `-f` and the error-
> > message in the case that `-6` was used without `-f`.
> > 
> > Link: http://bugs.debian.org/610596
> > Signed-off-by: Jeremy Sowden <azazel@debian.org>
> > ---
> >  ipvsadm.c | 17 ++++++++++-------
> >  1 file changed, 10 insertions(+), 7 deletions(-)
> > 
> > diff --git a/ipvsadm.c b/ipvsadm.c
> > index 42f31a20e596..889128017bd1 100644
> > --- a/ipvsadm.c
> > +++ b/ipvsadm.c
> > @@ -523,7 +523,7 @@ static int
> >  parse_options(int argc, char **argv, struct ipvs_command_entry *ce,
> >  	      unsigned long long *options, unsigned int *format)
> >  {
> > -	int c, parse;
> > +	int c, parse, ipv6 = 0;
> >  	poptContext context;
> >  	char *optarg = NULL, sched_flags_arg[128];
> >  	struct poptOption options_table[] = {
> > @@ -829,12 +829,7 @@ parse_options(int argc, char **argv, struct ipvs_command_entry *ce,
> >  			*format |= FMT_EXACT;
> >  			break;
> >  		case '6':
> > -			if (ce->svc.fwmark) {
> > -				ce->svc.af = AF_INET6;
> > -				ce->svc.netmask = 128;
> > -			} else {
> > -				fail(2, "-6 used before -f\n");
> > -			}
> > +			ipv6 = 1;
> >  			break;
> >  		case 'o':
> >  			set_option(options, OPTC_ONEPACKET);
> > @@ -935,6 +930,14 @@ parse_options(int argc, char **argv, struct ipvs_command_entry *ce,
> >  		return -1;
> >  	}
> >  
> > +	if (ipv6) {
> > +		if (ce->svc.fwmark) {
> > +			ce->svc.af = AF_INET6;
> 
> 	As ce->svc.af is set later after all options are processed,
> the -M option will always see AF_INET in ce->svc.af ...
> 
> > +			ce->svc.netmask = 128;
> 
> 	Now we override the value from -M, so we can not do
> this here.

Ah, right.  Thanks.  The simplest thing, then, would be just to reword
the error message to something like:

	fail(2, "-6 must follow -f\n");

Will respin.

J.

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