Re: vmctl: off-by-one error handling mixing -a with a VM id

[Preben Guldberg]

Dave Voutila wrote:
> Preben Guldberg writes:
> > The patch below addresses an off-by-one error reading argv when
> > generating the error message.

> > I personally find it clearer if the condition of mixing -a with an id
> > is highlighted. I included a suggestion in the patch below.

> Since -a and providing an id are mutually exclusive, I think it's more
> helpful to print usage information via ctl_usage(res->ctl). From the
> usage details, it's self explanatory what's wrong.

>   usage:  vmctl [-v] stop [-fw] [id | -a]

The updated diff below would do just that:

    % vmctl stop -a testvm
    usage:  vmctl [-v] stop [-fw] [id | -a]

diff 09b708f572d76de8db7f7948ea7359b19bbd1c5a /usr/src
blob - 249eaa3ded1ee9c804a81874613c292a74ea4b21
file + usr.sbin/vmctl/main.c
--- usr.sbin/vmctl/main.c
+++ usr.sbin/vmctl/main.c
@@ -961,7 +961,7 @@ ctl_stop(struct parse_result *res, int argc, char *arg
        /* VM id is only expected without the -a flag */
        if ((res->action != CMD_STOPALL && ret == -1) ||
            (res->action == CMD_STOPALL && ret != -1))
-               errx(1, "invalid id: %s", argv[1]);
+               ctl_usage(res->ctl);
 
        return (vmmaction(res));
 }