linux-kernel - Re: [PATCH] vsprintf: sanely handle NULL passed to %pe

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Message-ID: <CAHp75VeJm-hbbtVAu69ZbDCCjs9cUK922D=hhW-MVu5OxczDzg@mail.gmail.com>
Date:   Wed, 19 Feb 2020 13:25:25 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Ilya Dryomov <idryomov@...il.com>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        "Tobin C . Harding" <me@...in.cc>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Documentation List <linux-doc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] vsprintf: sanely handle NULL passed to %pe

On Wed, Feb 19, 2020 at 1:21 PM Ilya Dryomov <idryomov@...il.com> wrote:
> On Wed, Feb 19, 2020 at 9:21 AM Rasmus Villemoes
> <linux@...musvillemoes.dk> wrote:
> >
> > Extend %pe to pretty-print NULL in addition to ERR_PTRs,
> > i.e. everything IS_ERR_OR_NULL().

...

> > +       [0] = "NULL",

> > +       test("[NULL]", "[%pe]", NULL);

> FWIW I was about to post a patch that just special cases NULL here.
>
> I think changing errname() to return "NULL" for 0 is overkill.
> People will sooner or later discover that function and start using it
> in contexts that don't have anything to do with pointers.  Returning
> _some_ string for 0 (instead of NULL) makes it very close to standard
> strerror(), and "NULL" for 0 (i.e. success) seems rather odd.

%pe is specifically for _pointers_. I don't see a point in your comment.

-- 
With Best Regards,
Andy Shevchenko