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

12 Oct 2010


      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().