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Subject: Re: [PATCH v3] string.h: Add str_has_prefix() helper
From:   Joe Perches <joe@perches.com>
To:     Steven Rostedt <rostedt@goodmis.org>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Tom Zanussi <zanussi@kernel.org>
Date:   Fri, 21 Dec 2018 16:22:20 -0800
In-Reply-To: <20181221190629.6f7fdf74@gandalf.local.home>
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         <20181221190629.6f7fdf74@gandalf.local.home>
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On Fri, 2018-12-21 at 19:06 -0500, Steven Rostedt wrote:
> On Fri, 21 Dec 2018 18:13:16 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > +static __always_inline int str_has_prefix(const char *str, const char *prefix)
> 
> I'm thinking it is cleaner to have two helper functions and have them
> both return bool.
> 
> static __always_inline bool str_has_prefix(const char *str, const char *prefix)
> {
> 	return !strncmp(str, prefix, strlen(prefix));
> }
> 
> ( I still like to keep the __always_inline, it doesn't hurt )
> 
> And I'll make a separate patch that adds:
> 
> static __always_inline bool
> str_has_prefix_len(const char *str, const char *prefix, unsigned int *len)
> {
> 	*len = strlen(prefix);
> 	return !strncmp(str, prefix, *len) ? *len : 0;
> }
> 
> Everyone OK with that? 

I guess so as you're the one doing all the work.

Trivia:

Shouldn't the latter function use __kernel_size_t
as that's the actual return type of strlen?

Thanks for keeping at it.