linux-ext4 - RE: [PATCH v1 2/3] lib/string_helpers: Change returned value of the strreplace()

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Message-ID: <989d091b100a4dfcbce0dce81b48e672@AcuMS.aculab.com>
Date:   Thu, 23 Mar 2023 22:23:11 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Kees Cook' <keescook@...omium.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.com>,
        Andy Shevchenko <andy@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: RE: [PATCH v1 2/3] lib/string_helpers: Change returned value of the
 strreplace()

From: Kees Cook
> Sent: 22 March 2023 16:51
> 
> On Wed, Mar 22, 2023 at 04:12:05PM +0200, Andy Shevchenko wrote:
> > It's more useful to return the original string with strreplace(),

Won't that break anything that is using the result?

> I found the use of "original" confusing here and in the comments. This
> just returns arg 1, yes? i.e. it's not the original (unreplaced) string,
> but rather just the string itself.
> 
> I agree, though, that's much more useful than a pointer to the end of
> the string.

If you want a pointer to the start of the string, you've
already got it.
Almost all the time you can do the assignment first.

But if you want a pointer to the end you'll need to scan it again.

I have a feeling that the reason many of the string functions
return the original pointer is a historic side effect of
the original implementation.
Going back to before C had a 'return' statement.

	David

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