Re: [PATCH v4 05/11] seq_buf: Add seq_buf_strlen()

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Sun, Oct 04, 2026 at 12:26:39AM -0700, Kees Cook wrote:
> On Sat, Oct 03, 2026 at 06:36:49PM +0300, Andy Shevchenko wrote:
> > On Fri, Oct 02, 2026 at 08:59:10PM -0700, Kees Cook wrote:

...

> > >  static inline const char *seq_buf_str(struct seq_buf *s)
> > >  {
> > > -	if (WARN_ON(s->size == 0))
> > > +	if (s->size == 0)
> > >  		return "";
> > >  
> > > -	if (seq_buf_buffer_left(s))
> > > -		s->buffer[s->len] = 0;
> > > -	else
> > > -		s->buffer[s->size - 1] = 0;
> > > +	__seq_buf_terminate(s);
> > >  
> > >  	return s->buffer;
> > >  }
> > 
> > Looking at this again, can't it be rewritten now using _strlen()?
> > 
> > 	if (seq_buf_strlen(s))
> > 		return s->buffer;
> > 
> > 	return "";
> > 
> > ?
> 
> It could, but I'm vaguely nervous about the difference between
> 	s->buffer[0] == '\0'
> and
> 	.data ""
> 
> i.e. we only force the return of seq_buf_str() to be _not_ just
> s->buffer when s->buffer is weirdly impossible (due to size == 0).
> I'd rather not make all 0-len strings return the .data segment's const
> "" string...

Good point. Perhaps then to add a short note to the kernel doc,
so we won't see patches based on the suggestion like I gave?

-- 
With Best Regards,
Andy Shevchenko