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

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Date:   Fri, 26 Jun 2020 04:10:32 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>
Cc:     rjw@...ysocki.net, viresh.kumar@...aro.org, lenb@...nel.org,
        dsmythies@...us.net, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, x86@...nel.org, jic23@....ac.uk,
        keescook@...omium.org, akpm@...ux-foundation.org
Subject: Re: [PATCH] lib: Extend kstrtobool() to accept "true"/"false"

On Fri, 2020-06-26 at 12:44 +0200, Peter Zijlstra 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?
looks good.

Thanks,
Srinvas

> 
> ---
> 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>
> ---
>  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;
>  	}