Re: [PATCH v1 3/7] xen: xenstore: add possibility to preserve owner

[David Woodhouse <dwmw2@xxxxxxxxxxxxx>]

On Sat, 2023-11-11 at 11:01 +0000, David Woodhouse wrote:
> 
> > --- a/hw/xen/xen-operations.c
> > +++ b/hw/xen/xen-operations.c
> > @@ -300,6 +300,18 @@ static bool libxenstore_create(struct qemu_xs_handle 
> > *h, xs_transaction_t t,
> >          return false;
> >      }
> >  
> > +    if (owner == XS_PRESERVE_OWNER) {
> > +        struct xs_permissions *tmp;
> > +        unsigned int num;
> > +
> > +        tmp = xs_get_permissions(h->xsh, 0, path, &num);
> > +        if (tmp == NULL) {
> > +            return false;
> > +        }
> > +        perms_list[0].id = tmp[0].id;
> > +        free(tmp);
> > +    }
> > +
> 
> Don't see what saves you from someone else changing it at this point on
> true Xen though. Which is why I'd prefer XenStore to do it natively.

I suppose maybe you could do it in a transaction *if* the transaction_t
you're passed in isn't already XBT_NULL?

One might argue that the mkdir+set_perms in libxenstore_create() ought
to have been within the same transaction *anyway*?

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