linux-kernel - Re: [RFC PATCH v1 07/12] efi: Replace strstarts() by str_has

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Message-ID: <20201207101025.1d133a5d@gandalf.local.home>
Date:   Mon, 7 Dec 2020 10:10:25 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     James Bottomley <James.Bottomley@...senPartnership.com>
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        laniel_francis@...vacyrequired.com,
        linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v1 07/12] efi: Replace strstarts() by
 str_has_prefix().

On Sat, 05 Dec 2020 15:04:31 -0800
James Bottomley <James.Bottomley@...senPartnership.com> wrote:

> Well, I think the pattern
> 
> if (strstarts(option, <string>)) {
>    ...
>    option += strlen(<same string>);
> 
> is a bad one because one day <string> may get updated but not <same
> string>.  And if <same string> is too far away in the code it might not  
> even show up in the diff, leading to reviewers not noticing either.  So
> I think eliminating the pattern is a definite improvement.

And one of the reasons we created str_has_prefix() is because we fixed that
exact bug, in a few places.

It was caused by a typo, where we had something like:

	strstarts(option, "foo=") {
		option += strlen("foo");

and forgot the "=" part, and broke the rest of the logic.

-- Steve