Re: [patch] ASoC: soc: snprintf() doesn't return negative

Dan Carpenter
2010-10-12T10:40:22Z

On Tue, Oct 12, 2010 at 10:56:05AM +0100, Mark Brown wrote:
> On Tue, Oct 12, 2010 at 11:49:27AM +0200, Takashi Iwai wrote:
> > Mark Brown wrote:
>
> > Argh, yes, I'm (again) confused by that behavior.
> > The problem is the potential buffer overflow, indeed. snprintf()
> > returns the size that would be printed. Thus a safe code would be
> > like:
> >
> > list_for_each_entry(dai, &dai_list, list) {
> > int len = snprintf(buf + ret, PAGE_SIZE - ret, "%s\n", dai->name);
> > if (len < 0)
> > continue;
> > ret += len;
> > if (ret >= PAGE_SIZE) {
> > ret = PAGE_SIZE;
> > break;
> > }
> > }
>
> Yes, this form is better for that variant of the loop - that is safe and
> legible without relying on current implementation details of snprintf().

This is fine with me as well. My original patch had a problem with the
WARN_ON() so your version is better.

regards,
dan carpenter