Re: bind(2): Missing [[gnu::nonnull]]

[Xi Ruoyao via Libc-alpha <libc-alpha@sourceware.org>]

On Sat, 2022-12-03 at 16:33 +0100, Alejandro Colomar via Libc-alpha
wrote:
> Hi!
> 
> I'm documenting NULLness of parameters in the Linux man-pages.  While doing 
> that, I noticed bind(2) is not prototyped with nonnull, but I don't think it 
> makes sense to accept NULL.  Is it a mistake?  Should I send a patch for adding it?

Hi Alejandro,

Currently the man page says:

EFAULT: addr points outside the user's accessible address space.

And bind(2) indeed sets errno to EFAULT and return -1 when NULL is
passed as addr.

gnu::nonnull is not only a diagnostic attribute: it also allows the
compiler to assume addr is never NULL.  i. e. if addr was gnu::nonnull
and bind(2) is called with addr == NULL, the behavior would be
undefined.

So this will be an API change.  Yes I agree calling bind with NULL does
not make any sense, but I guess we still need to keep API
"compatibility" with those nonsense code...

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University