[PATCH 2/5] manual: Document error codes missing for 'if_indextoname'

[Maciej W. Rozycki]

On Mon, 26 May 2025, Florian Weimer wrote:

> > +@item ENOSYS
> > +This function is not implemented.
> > +@end table
> 
> I think ENOSYS comes from the unused stub, so we don't need to document
> it.  The Hurd implementation has an error path for ENOSYS, but that
> looks effectively dead (it requires a race condition on the socket
> descriptor).

 Is it this code sequence:

  if (__ioctl (fd, SIOCGIFNAME, &ifr) < 0)
    {
      int saved_errno = errno;
      __close (fd);
      if (saved_errno == EINVAL || saved_errno == ENOTTY)
        __hurd_fail (ENOSYS);

that you refer to?  If so, then it seems like an implementation bug to me, 
as POSIX has it:

[ENOSYS]
     Functionality not supported.  An attempt was made to use optional 
     functionality that is not supported in this implementation.

which does not seem adequate for reporting a request failure coming from a 
race condition.

  Maciej