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From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Ard Biesheuvel <ardb@kernel.org>, laniel_francis@privacyrequired.com
Cc: linux-efi <linux-efi@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v1 07/12] efi: Replace strstarts() by str_has_prefix().
Date: Fri, 04 Dec 2020 10:02:09 -0800	[thread overview]
Message-ID: <ab769a5188394cd3379cc627d14a0222050a1367.camel@HansenPartnership.com> (raw)
In-Reply-To: <CAMj1kXEQhT_LF5FDBO3-S7pBn55wG59bQUVr2q58A4FhqodY8Q@mail.gmail.com>

On Fri, 2020-12-04 at 18:07 +0100, Ard Biesheuvel wrote:
> On Fri, 4 Dec 2020 at 18:06, <laniel_francis@privacyrequired.com>
> wrote:
> > From: Francis Laniel <laniel_francis@privacyrequired.com>
> > 
> > The two functions indicates if a string begins with a given prefix.
> > The only difference is that strstarts() returns a bool while
> > str_has_prefix()
> > returns the length of the prefix if the string begins with it or 0
> > otherwise.
> > 
> 
> Why? 

I think I can answer that.  If the conversion were done properly (which
it's not) you could get rid of the double strings in the code which are
error prone if you update one and forget another.  This gives a good
example: 3d739c1f6156 ("tracing: Use the return of str_has_prefix() to
remove open coded numbers"). so in your code you'd replace things like

    if (strstarts(option, "rgb")) {
        option += strlen("rgb");
        ...

with 

    len = str_has_prefix(option, "rgb");
    if (len) {
        option += len
        ...
 
Obviously you also have cases where strstart is used as a boolean with
no need to know the length ... I think there's no value to converting
those.

James



  parent reply	other threads:[~2020-12-04 18:03 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-04 17:03 [RFC PATCH v1 00/12] " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 01/12] arm: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 02/12] mips: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 03/12] crypto: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 04/12] device-mapper: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 05/12] renesas: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 06/12] omap: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 07/12] efi: " laniel_francis
2020-12-04 17:07   ` Ard Biesheuvel
2020-12-04 17:19     ` Francis Laniel
2020-12-04 18:02     ` James Bottomley [this message]
2020-12-05 19:08       ` Francis Laniel
2020-12-05 19:36       ` Ard Biesheuvel
2020-12-05 20:24         ` James Bottomley
2020-12-05 20:57           ` Ard Biesheuvel
2020-12-05 21:15             ` James Bottomley
2020-12-05 21:20               ` Ard Biesheuvel
2020-12-05 23:04                 ` James Bottomley
2020-12-07 15:10                   ` Steven Rostedt
2020-12-07 16:25                     ` David Laight
2020-12-05 20:28         ` Rasmus Villemoes
2020-12-10 18:14         ` Arvind Sankar
2020-12-11  9:45           ` David Laight
2020-12-11 16:10             ` Arvind Sankar
2020-12-04 17:03 ` [RFC PATCH v1 08/12] ide: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 09/12] mips: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 10/12] module: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 11/12] musb: " laniel_francis
2020-12-04 17:03 ` [RFC PATCH v1 12/12] string.h: Remove strstarts() laniel_francis
2020-12-04 17:56 ` [RFC PATCH v1 00/12] Replace strstarts() by str_has_prefix() James Bottomley

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