Re: [PATCHv2 2/7] xread: poll on non blocking fds

> >> So the code would look like this:
> >>
> >>    if (!poll(&pfd, 1, -1))
> >>       return -1;
> > 
> > That changes the semantics of the function. The poll() is just a
> > convenience to avoid spinning. If it fails, with Stefan's patch[1] the
> > worst case is that we would spin on read() and poll(), instead of
> > actually blocking in the poll().
> > 
> > But if we return on poll() failure, now the caller will see errors from
> > poll() even though they don't know or care that we called poll() in the
> > first place. Consider what would happen with your code if read got
> > EAGAIN and then poll got EINTR. We would report an error, even though
> > the whole point of xread() is to loop on these conditions.
> [...]
>
> /* So the code v2 would look like this: */
> 
>     if (!poll(&pfd, 1, -1)) {
>         if (errno == EINTR)
>             continue;
>          return -1; /* poll() failed, this is serious. */
>     }