Re: [Qemu-devel] [PATCH v1 04/15] qcow: require image size to be > 1 for new images

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Jan 16, 2017 at 08:41:15PM +0100, Max Reitz wrote:
> On 03.01.2017 19:27, Daniel P. Berrange wrote:
> > The qcow driver refuses to open images which are less than
> > 2 bytes in size, but will happily create such images. Add
> > a check in the create path to avoid this discrepancy.
> > 
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> > ---
> >  block/qcow.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/block/qcow.c b/block/qcow.c
> > index 7540f43..8133fda 100644
> > --- a/block/qcow.c
> > +++ b/block/qcow.c
> > @@ -799,6 +799,12 @@ static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
> >      /* Read out options */
> >      total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
> >                            BDRV_SECTOR_SIZE);
> > +    if (total_size <= 1) {
> > +        error_setg(errp, "Image size is too small (must be at least 2 bytes)");
> > +        ret = -EINVAL;
> > +        goto cleanup;
> > +    }
> > +
> 
> Given the ROUND_UP() before, I can't see how total_size can be 1, but I
> can see how it can be 0. Since that is covered by this condition:
> 
> Reviewed-by: Max Reitz <mreitz@redhat.com>

I'll switch to == 0 none the less


Regards,
Daniel
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