netdev - Re: [PATCH ethtool-next] Fixing boolean value output for Netlink reported values in JSON format

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Message-ID: <CAP5jrPGXVKsSNm=9M-7du4zB0errcmR9qHuu_GO=bvTZtccaRA@mail.gmail.com>
Date:   Fri, 6 Jan 2023 15:16:30 -0700
From:   Max Georgiev <glipus@...il.com>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     mkubecek@...e.cz, netdev@...r.kernel.org, kuba@...nel.org
Subject: Re: [PATCH ethtool-next] Fixing boolean value output for Netlink
 reported values in JSON format

On Thu, Jan 5, 2023 at 5:11 AM Simon Horman <simon.horman@...igine.com> wrote:
>
> On Tue, Dec 27, 2022 at 10:36:20AM -0700, Maxim Georgiev wrote:
> > Current implementation of show_bool_val() passes "val" parameter of pointer
> > type as a last parameter to print_bool():
> > https://git.kernel.org/pub/scm/network/ethtool/ethtool.git/tree/netlink/netlink.h#n131
> > ...
> > static inline void show_bool_val(const char *key, const char *fmt, uint8_t *val)
> > {
> >       if (is_json_context()) {
> >               if (val)
> > >                     print_bool(PRINT_JSON, key, NULL, val);
> >       } else {
> > ...
> > print_bool() expects the last parameter to be bool:
> > https://git.kernel.org/pub/scm/network/ethtool/ethtool.git/tree/json_print.c#n153
> > ...
> > void print_bool(enum output_type type,
> >               const char *key,
> >               const char *fmt,
> >               bool value)
> > {
> > ...
> > Current show_bool_val() implementation converts "val" pointer to bool while
> > calling show_bool_val(). As a result show_bool_val() always prints the value
> > as "true" as long as it gets a non-null pointer to the boolean value, even if
> > the referred boolean value is false.
> >
> > Fixes: 7e5c1ddbe67d ("pause: add --json support")
> > Signed-off-by: Maxim Georgiev <glipus@...il.com>
>
> Reviewed-by: Simon Horman <simon.horman@...igine.com>
>
> I'm assuming that val is never NULL :)

Simon, thank you for taking a look!
Yes, the "if (val)" check on line 130 guarantees that "print_bool()"
on line 131 is called only if val is not null.

>
> > ---
> >  netlink/netlink.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/netlink/netlink.h b/netlink/netlink.h
> > index 3240fca..1274a3b 100644
> > --- a/netlink/netlink.h
> > +++ b/netlink/netlink.h
> > @@ -128,7 +128,7 @@ static inline void show_bool_val(const char *key, const char *fmt, uint8_t *val)
> >  {
> >       if (is_json_context()) {
> >               if (val)
> > -                     print_bool(PRINT_JSON, key, NULL, val);
> > +                     print_bool(PRINT_JSON, key, NULL, *val);
> >       } else {
> >               print_string(PRINT_FP, NULL, fmt, u8_to_bool(val));
> >       }
> > --
> > 2.38.1
> >