On Wed, Nov 18, 2020 at 09:12:26 +0100, Michal Privoznik wrote:
> On 11/18/20 8:59 AM, Peter Krempa wrote:
> > On Tue, Nov 17, 2020 at 12:28:27 +0100, Michal Privoznik wrote:
> > > Similarly to previous commits, we can utilize domCaps to check if
> > > graphics type is supported.
> > >
> > > Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
> > > ---
> > > src/qemu/qemu_capabilities.c | 2 +-
> > > src/qemu/qemu_capabilities.h | 3 +++
> > > src/qemu/qemu_validate.c | 40 ++++++++++++------------------------
> > > 3 files changed, 17 insertions(+), 28 deletions(-)
> >
> > [...]
> >
> > > @@ -3903,15 +3892,12 @@ qemuValidateDomainDeviceDefGraphics(const virDomainGraphicsDef *graphics,
> > > }
> > > break;
> > > +
> > > + case VIR_DOMAIN_GRAPHICS_TYPE_VNC:
> > > case VIR_DOMAIN_GRAPHICS_TYPE_RDP:
> > > case VIR_DOMAIN_GRAPHICS_TYPE_DESKTOP:
> > > - virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> > > - _("unsupported graphics type '%s'"),
> > > - virDomainGraphicsTypeToString(graphics->type));
> > > - return -1;
> > > case VIR_DOMAIN_GRAPHICS_TYPE_LAST:
> > > - default:
> > > - return -1;
> > > + break;
> >
> > Removing 'default: ' is not necessary once you use proper type for the
> > variable in the switch statement, which is our usual approach.
>
> I guess I don't need to typecast ->type since it's already stored as
> virDomainGraphicsType in the struct.
>
> >
> > The default and _LAST case should use virReportEnumRangeError.
> >
> >
>
> I'm not sure it's adding useful code. In this very patch I'm adding a check
> that rejects unknown values for ->type and thus I don't see a way how the
> control could hit any of these 'case', or 'default'.
You are right it won't .
A drawback of using the capability code is that
it relies on converting the type to a bit array stored in "unsigned int"
without any overflow safeguards. Once a device model or type enum
reaches 33 entries, the code will start failing without any obvious
sign.
virDomainCapsEnumSet which is internally used by the VIR_DOMAIN_CAPS_ENUM_SET
which is used by virQEMUCapsFillDomainDeviceGraphicsCaps to fill the
bitmap catches overflow but the callers neglect to propagate it.
