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Re: [libvirt] [PATCH 01/14] Add XML flag for internal domain status



On Mon, Jul 20, 2009 at 02:54:34PM +0100, Mark McLoughlin wrote:
> On Mon, 2009-07-20 at 14:06 +0100, Daniel P. Berrange wrote:
> > On Mon, Jul 20, 2009 at 02:18:38PM +0200, Daniel Veillard wrote:
> >  
> > >   Hum, that's very confusing. Why expose that flag at the API level
> > > but forbid it's use from the API ?
> > >   Seems to me adding an extra parameter to the internal function
> > > virDomainDefParseXML() is a far cleaner way to do things by looking at
> > > this patch.
> > 
> > It'd be nice to only have 1 flag parameter for the internal methods.
> > Having 'flags' and 'privateFlags' to the same method is just going
> > to lead to code errors, passing the wrong flag in and it silently
> > failing 
> > 
> > We should not be adding this to the public API header file though.
> > 
> > Since we only have 2 flags in use currently, lets just mask off
> > the top 16 bits for internal use.
> > 
> > So in domain_conf.h add a enum starting at the 16th bit
> > 
> > 
> >    typedef enum {
> >      VIR_DOMAIN_XML_INTERNAL_STATUS = (1<<16), /* dump internal domain status information */
> >   } virDomainXMLInternalFlags;
> > 
> > 
> > And to be sure no one abusing this from public API, in
> > virDomainGetXMLDesc() scrub the incoming flags
> > 
> >   flags = flags & 0xffff;
> 
> How's this?
> 
> Cheers,
> Mark.
> 
> From: Mark McLoughlin <markmc redhat com>
> Subject: [PATCH 01/14] Add internal XML parsing/formatting flag
> 
> We need to store things like device names and PCI slot numbers in the
> qemu domain state file so that we don't lose that information on
> libvirtd restart. Add a flag to indicate that this information should
> be parsed or formatted.
> 
> Make bit 16 and above of the flags bitmask for internal use only and
> consume the first bit for this new status flag.
> 
> * include/libvirt/libvirt.h: add VIR_DOMAIN_XML_FLAGS_MASK
> 
> * src/libvirt.c: reject private flags in virDomainGetXMLDesc()
> 
> * src/domain_conf.h: add VIR_DOMAIN_XML_INTERNAL_STATUS
> 
> * src/domain_conf.c: pass the flag from virDomainObjParseXML() and
>   virDomainSaveStatus
> ---
>  include/libvirt/libvirt.h    |    5 +++--
>  include/libvirt/libvirt.h.in |    5 +++--
>  src/domain_conf.c            |    8 ++++----
>  src/domain_conf.h            |    5 +++++
>  src/libvirt.c                |    6 ++++++
>  5 files changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/include/libvirt/libvirt.h b/include/libvirt/libvirt.h
> index 90007a1..d1cf5fb 100644
> --- a/include/libvirt/libvirt.h
> +++ b/include/libvirt/libvirt.h
> @@ -584,8 +584,9 @@ int                     virDomainGetSecurityLabel (virDomainPtr domain,
>   */
>  
>  typedef enum {
> -    VIR_DOMAIN_XML_SECURE = 1, /* dump security sensitive information too */
> -    VIR_DOMAIN_XML_INACTIVE = 2/* dump inactive domain information */
> +    VIR_DOMAIN_XML_SECURE     = (1<<0), /* dump security sensitive information too */
> +    VIR_DOMAIN_XML_INACTIVE   = (1<<1), /* dump inactive domain information */
> +    VIR_DOMAIN_XML_FLAGS_MASK = 0xffff, /* bits 16 and above are for internal use */
>  } virDomainXMLFlags;

IMHO, this should be kept in the private header file. The fact that
we have hack reserving some portion for our internal use doesn't need
to be exposed to applications.

> diff --git a/src/libvirt.c b/src/libvirt.c
> index f4a7fa7..5507750 100644
> --- a/src/libvirt.c
> +++ b/src/libvirt.c
> @@ -2730,6 +2730,12 @@ virDomainGetXMLDesc(virDomainPtr domain, int flags)
>          goto error;
>      }
>  
> +    if (flags != (flags & VIR_DOMAIN_XML_FLAGS_MASK)) {
> +        virLibConnError(conn, VIR_ERR_OPERATION_DENIED,
> +                        _("virDomainGetXMLDesc with internal flags"));
> +        goto error;
> +    }

Here I just think we should be masking the flags off silently. There's
no need  to explicit tell apps about the existance of internal flags.


Daniel
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