Re: [Qemu-devel] [PULL 10/25] util: Add qemu_guest_getrandom and associated routines

[Peter Maydell <peter.maydell@linaro.org>]

On Thu, 30 May 2019 at 14:41, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> On 5/30/19 6:29 AM, Peter Maydell wrote:
> > On Wed, 22 May 2019 at 19:42, Richard Henderson
> > <richard.henderson@linaro.org> wrote:
> >>
> >> This routine is intended to produce high-quality random numbers to the
> >> guest.  Normally, such numbers are crypto quality from the host, but a
> >> command-line option can force the use of a fully deterministic sequence
> >> for use while debugging.
> >
> >> +void qemu_guest_getrandom_nofail(void *buf, size_t len)
> >> +{
> >> +    qemu_guest_getrandom(buf, len, &error_fatal);
> >> +}
> >>
> >
> > Hi; Coverity complains about this because in the other 4 places
> > where we call qemu_guest_getrandom() we check its return
> > value, but here we ignore it. If qemu_guest_getrandom() can't
> > fail ever then we don't need the separate _nofail() version.
> > If it can fail sometimes but not here then we should assert()
> > so with a comment explaining why it can't fail, or we should
> > do an error-exit check like qdev_init_nofail().
> > (This is CID 1401701.)
>
> Because of &error_fatal, we will have already exited on error.  As a qapi
> programming pattern, that seems clear in this context.

Whoops, I didn't see the error_fatal. I think that a cast to void
will indeed silence the Coverity error (at least a quick google
search suggests it will).

thanks
-- PMM