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

Mark Brown
2010-10-12T09:56:05Z

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().