Re: [Qemu-devel] [PATCH] net/slirp: fix the error message when the prefix len is invalid

[Stefano Garzarella <sgarzare@redhat.com>]

On Thu, May 09, 2019 at 04:54:35PM +0200, Markus Armbruster wrote:
> Stefano Garzarella <sgarzare@redhat.com> writes:
> 
> > Add a missing parentheses at the end of the error message,
> > when we have an invalid prefix len.
> >
> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> > ---
> >  net/slirp.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/slirp.c b/net/slirp.c
> > index 95934fb36d..0f4ae0abc0 100644
> > --- a/net/slirp.c
> > +++ b/net/slirp.c
> > @@ -498,7 +498,8 @@ static int net_slirp_init(NetClientState *peer, const char *model,
> >      }
> >      if (vprefix6_len < 0 || vprefix6_len > 126) {
> >          error_setg(errp,
> > -                   "Invalid prefix provided (prefix len must be in range 0-126");
> > +                   "Invalid prefix provided "
> > +                   "(prefix len must be in range 0-126)");
> >          return -1;
> >      }
> 
> Preexisting: the error message fails to identify the offending
> parameter.  The user needs to make the connection to "ipv6-prefixlen"
> based on the fact that the only parameters with "prefix" in name or
> description are "ipv6-prefix" and "ipv6-prefixlen", and only the latter
> is a length.
> 
> What about "Parameter 'ipv6-prefixlen' expects a length below 127", or
> "Parameter 'ipv6-prefixlen' expects a value between 0 and 126"?

"Parameter 'ipv6-prefixlen' expects a value between 0 and 126" should be
fine.

Otherwise, since other errors didn't refer to the parameter name, we can
simply add IPv6 in this way:
"Invalid IPv6 prefix provided (IPv6 prefix len must be between 0 and 126)"

But I'm fine also with your proposal.

Thanks,
Stefano