From mboxrd@z Thu Jan  1 00:00:00 1970
From: Takashi Iwai <tiwai@suse.de>
Subject: Re: [PATCH v2 07/13] topology: Add private data parser
Date: Tue, 07 Jul 2015 18:19:57 +0200
Message-ID: <s5h7fqchrde.wl-tiwai@suse.de>
References: <1435758275-4047-1-git-send-email-liam.r.girdwood@linux.intel.com>
 <1435758275-4047-7-git-send-email-liam.r.girdwood@linux.intel.com>
 <s5ha8vflui3.wl-tiwai@suse.de> <1436284442.7271.30.camel@loki>
Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka")
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <alsa-devel-bounces@alsa-project.org>
Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15])
 by alsa0.perex.cz (Postfix) with ESMTP id EAB382654EF
 for <alsa-devel@alsa-project.org>; Tue,  7 Jul 2015 18:19:59 +0200 (CEST)
In-Reply-To: <1436284442.7271.30.camel@loki>
List-Unsubscribe: <http://mailman.alsa-project.org/mailman/options/alsa-devel>,
 <mailto:alsa-devel-request@alsa-project.org?subject=unsubscribe>
List-Archive: <http://mailman.alsa-project.org/pipermail/alsa-devel/>
List-Post: <mailto:alsa-devel@alsa-project.org>
List-Help: <mailto:alsa-devel-request@alsa-project.org?subject=help>
List-Subscribe: <http://mailman.alsa-project.org/mailman/listinfo/alsa-devel>,
 <mailto:alsa-devel-request@alsa-project.org?subject=subscribe>
Errors-To: alsa-devel-bounces@alsa-project.org
Sender: alsa-devel-bounces@alsa-project.org
To: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Cc: Vinod Koul <vinod.koul@intel.com>, "Jin, Yao" <yao.jin@linux.intel.com>, Mark Brown <broonie@kernel.org>, alsa-devel@alsa-project.org
List-Id: alsa-devel@alsa-project.org

On Tue, 07 Jul 2015 17:54:02 +0200,
Liam Girdwood wrote:
> 
> On Wed, 2015-07-01 at 18:20 +0200, Takashi Iwai wrote:
> 
> > 
> > > +static int get_hex_num(const char *str)
> > > +{
> > > +	char *tmp, *s = NULL;
> > > +	int i = 0;
> > > +
> > > +	tmp = strdup(str);
> > > +	if (tmp == NULL)
> > > +		return -ENOMEM;
> > > +
> > > +	s = strtok(tmp, ",");
> > > +	while (s != NULL) {
> > > +		s = strtok(NULL, ",");
> > > +		i++;
> > > +	}
> > > +
> > > +	free(tmp);
> > > +	return i;
> > 
> > Hmm, this just counts the number of comma + 1, so you don't need to
> > duplicate the string?
> > 
> 
> The string here is duplicated since strtok is destructive (it overwrites
> the delimiters with NULL) and the string is being used later on by the
> calling function.

Yes, but what I meant is something like below:

static int get_hex_num(const char *str)
{
	int i = 0;

	if (!*str)
		return 0;
	for (;;) {
		i++;
		str = strchr(str, ',');
		if (!str)
			return i;
		str++;
	}
}

... so that it works without strdup().

But it seems that strtok() skips the starting delimiter or handles
multiple delimiters as a single, so the result will become
inconsistent.  That is, all the following strings will give "a" and
"b" via strtok():
	a,b
	a,,b
	,a,b
	a,b,

I guess you don't want to have an empty list element, right?


Takashi