linux-kernel - Re: [PATCH] lib: Extend kstrtobool() to accept "true"/"false"

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Date:   Fri, 26 Jun 2020 17:49:26 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Borislav Petkov <bp@...en8.de>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Len Brown <lenb@...nel.org>,
        Doug Smythies <dsmythies@...us.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>, jic23@....ac.uk,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] lib: Extend kstrtobool() to accept "true"/"false"

On Fri, Jun 26, 2020 at 12:45 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Fri, Jun 26, 2020 at 12:22:55PM +0200, Peter Zijlstra wrote:
>
> > > This is too lax - it will be enabled for any !0 value. Please accept
> > > only 0 and 1.
> >
> > kstrtobool() ftw
>
> And looking at that, I find it really strange it does not in fact accept
> "true" / "false", so how about this?
>
> ---
> Subject: lib: Extend kstrtobool() to accept "true"/"false"
>
> Extend the strings recognised by kstrtobool() to cover:
>
>   - 1/0
>   - y/n
>   - yes/no      (new)
>   - t/f         (new)
>   - true/false  (new)
>   - on/off
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Reviewed-by: Rafael J. Wysocki <rafael@...nel.org>

> ---
>  lib/kstrtox.c | 60 ++++++++++++++++++++++++++++++++++++++++++++---------------
>  1 file changed, 45 insertions(+), 15 deletions(-)
>
> diff --git a/lib/kstrtox.c b/lib/kstrtox.c
> index 1006bf70bf74..b8b950325097 100644
> --- a/lib/kstrtox.c
> +++ b/lib/kstrtox.c
> @@ -325,9 +325,17 @@ EXPORT_SYMBOL(kstrtos8);
>   * @s: input string
>   * @res: result
>   *
> - * This routine returns 0 iff the first character is one of 'Yy1Nn0', or
> - * [oO][NnFf] for "on" and "off". Otherwise it will return -EINVAL.  Value
> - * pointed to by res is updated upon finding a match.
> + * This return return 0 on success, otherwise it will return -EINVAL.
> + * It will accept (case invariant):
> + *
> + *  - 1/0
> + *  - y/n
> + *  - yes/no
> + *  - t/f
> + *  - true/false
> + *  - on/off
> + *
> + * and set @*res to either true/false respectively.
>   */
>  int kstrtobool(const char *s, bool *res)
>  {
> @@ -335,30 +343,52 @@ int kstrtobool(const char *s, bool *res)
>                 return -EINVAL;
>
>         switch (s[0]) {
> +       case 't':
> +       case 'T':
> +               if (!s[1] || !strcasecmp(s, "true"))
> +                       goto have_true;
> +
> +               break;
> +
>         case 'y':
>         case 'Y':
> +               if (!s[1] || !strcasecmp(s, "yes"))
> +                       goto have_true;
> +
> +               break;
> +
>         case '1':
> +have_true:
>                 *res = true;
>                 return 0;
> +
> +       case 'f':
> +       case 'F':
> +               if (!s[1] || !strcasecmp(s, "false"))
> +                       goto have_false;
> +
> +               break;
>         case 'n':
>         case 'N':
> +               if (!s[1] || !strcasecmp(s, "no"))
> +                       goto have_false;
> +
> +               break;
>         case '0':
> +have_false:
>                 *res = false;
>                 return 0;
> +
>         case 'o':
>         case 'O':
> -               switch (s[1]) {
> -               case 'n':
> -               case 'N':
> -                       *res = true;
> -                       return 0;
> -               case 'f':
> -               case 'F':
> -                       *res = false;
> -                       return 0;
> -               default:
> -                       break;
> -               }
> +               if (!strcasecmp(s, "on"))
> +                       goto have_true;
> +
> +               if (!strcasecmp(s, "off"))
> +                       goto have_false;
> +
> +               break;
> +
>         default:
>                 break;
>         }