linux-kernel - Re: [PATCH 5/5] gpio: uapi: clarify the meaning of 'empty' char arrays

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Message-ID: <20201005130610.GA33067@sol>
Date:   Mon, 5 Oct 2020 21:06:10 +0800
From:   Kent Gibson <warthog618@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH 5/5] gpio: uapi: clarify the meaning of 'empty' char
 arrays

On Mon, Oct 05, 2020 at 02:01:22PM +0300, Andy Shevchenko wrote:
> On Mon, Oct 5, 2020 at 10:07 AM Kent Gibson <warthog618@...il.com> wrote:
> >
> > Clarify that a char array containing a string is considered 'empty' if
> > the first character is the null terminator. The remaining characters
> > are not relevant to this determination.
> 
> >   * @label: a functional name for this GPIO chip, such as a product
> > - * number, may be empty
> > + * number, may be empty (i.e. label[0] == '\0')
> 
> I would rather put it like
> "...may be empty string (i.e. label == "")"
> 

I'm not keen on that alternative as what it suggests is actually a
pointer comparison, and even if the user realizes that they may instead
use "strlen(label) == 0", when they shouldn't be assuming that a null
terminator is present in the array.  I avoided mentioning "string" and
kept it in terms of the char array for the same reason.

Cheers,
Kent.