On 10/14/19 3:45 AM, Max Reitz wrote:
+ need_snapshot_update = false;
+ for (i = 0; i < s->nb_snapshots; i++) {
+ if (s->snapshots[i].extra_data_size <
+ sizeof_field(QCowSnapshotExtraData, vm_state_size_large) +
+ sizeof_field(QCowSnapshotExtraData, disk_size))
Shorter as:
if (s->snapshots[i].extra_data_size < sizeof(QCowSnapshotExtraData))
but that's stylistic, so R-b still stands.
Yes, but if we ever add fields to QCowSnapshotExtraData, we shouldn’t
count them here. Therefore, I think we need to count exactly the fields
that the standard says are mandatory in v3.
If we ever add more fields, I'd prefer that we did something like:
struct QCowSnapshotExtraV3Minimum {
uint64_t vm_state_size_large;
uint64_t disk_size;
};
struct QCow3SnapshotExtraFull {
struct QCowSnapshotExtraV3Minimum base;
new fields...;
};
and use sane naming to get at extra members based on the expected types,
rather than trying to piecemeal portions of a type based on size.
Until we actually DO add more fields, why do we have to complicate the
current code?
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
