Re: [libvirt] [RFC] Add a new feild to qemud_save_header to tell if the saved image is corrupt

On 08/17/2011 07:10 AM, Osier Yang wrote: >If one tries to restore a domain from a corrupt save image, we blindly >goes forward to restore from it, this can cause many different errors, >depending on how much the image is saved. E.g. > >https://bugzilla.redhat.com/show_bug.cgi?id=730750 > >So I'm thinking if we can introduce a new feild to struct qemud_save_header, >such as "bool complete;", and set it true if succeeded to save the image, >false if not. So that could do some checking while trying to open the image >(qemuDomainSaveImageOpen), and quit early if "complete" is false, with >a sensiable error message. Almost. I think we can reuse one of the existing spare fields in the header (that is, change unused[15] to instead be unused[14] and make the new field a uint32_t), and I also think we need to have a tri-state value: 0 - save image was created with older libvirt, no idea if image is sane 1 - save image created by current libvirt, but not yet marked complete; attempts to restore from this image should fail with sensible message suggesting nuking the save image since it is broken - value written at start of save process 2 - save image created by current libvirt and completed - value written at end of save process And of course, we have to update the bswap_header routine to treat it with the same endianness as the rest of the header.