linux-kernel - Re: [for-next][PATCH 23/24] string.h: Add strncmp

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Message-ID: <20181221175514.647770cf@gandalf.local.home>
Date:   Fri, 21 Dec 2018 17:55:14 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Joe Perches <joe@...ches.com>
Cc:     Andreas Schwab <schwab@...ux-m68k.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Tom Zanussi <zanussi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [for-next][PATCH 23/24] string.h: Add strncmp_prefix() helper
 macro

On Fri, 21 Dec 2018 14:20:25 -0800
Joe Perches <joe@...ches.com> wrote:

> static inline bool str_has_prefix(const char *str, const char prefix[])
> {
> 	return !strncmp(str, prefix, strlen(prefix));
> }
> 
> eliminates the strlen with gcc 4.8 (oldest I still have)

I tested it a bit more before posting.

I tested it against:

gcc 4.5.1, 4.5.4, 4.6.3, 6.2.0, 7.2.0 and 8.2

And the strlen was eliminated each time.

So this looks like the right approach :-)

-- Steve