This reverts commit 1b57269c, and
subsequent refactorings of the function into new files.  There are no
callers of this function - I had originally proposed it for
implementing a new bulk snapshot API, but that proved to be too
invasive given RPC limits. I also tried using it for streamlining how
the qemu driver stores snapshot state across libvirtd restarts
internally, but in the end, the risks of a new internal format
outweighed the benefits of one file per snapshot.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

Now that the generic moment code does pretty much everything that both
snapshots and checkpoints will need, it's time to replace the
now-duplicate code in virdomainsnapshotobjlist.c with simpler calls
into the generic code. I considered using sub-classing (a
'virDomainMomentObjList parent;' member, but that requires making the
opaque type visible in headers; so for now, I stuck with a container
instead (a 'virDomainMomentObjListPtr base;' member).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

Now that we have made virDomainMomentObj sufficiently generic to
support both snapshots and checkpoints, it is time to rename the file
that it lives in. The split between a generic object and a list of the
generic objects doesn't buy us as much, so it will be easier to stick
all the moment list code in one file, with more code moving in the
next patch.  The changes during the move are fairly minor, although it
is worth pointing out that the log/error messages for the new file
report that they are from "domain", since the file will eventually be
shared by both "domain snapshot" and "domain checkpoint".
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

Now that the core of SnapshotObj is agnostic to snapshots and can be
shared with upcoming checkpoint code, it is time to rename the struct
and the functions specific to list operations. A later patch will
shuffle which file holds the common code. This is a fairly mechanical
patch.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

Another step towards making the object list reusable for both
snapshots and checkpoints: the list code only ever needs items that
are in the common virDomainMomentDef base type. This undoes a lot of
the churn in accessing common members added in the previous patch, and
the bulk of the patch is mechanical. But there was one spot where I
had to unroll a VIR_STEAL_PTR to work around changed types.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

Separate the algorithm for which list members to vist (which is
generic and can be shared with checkpoints, provided that common
filtering bits are either declared with the same value or have a
mapping from public API to common value) from the decision on which
members to return (which is specific to snapshots).  The typedef for
the callback function feels a bit heavy here, but will make it easier
to move the common portions in a later patch.

As part of the refactoring, note that the macros for selecting filter
bits are specific to listing functionality, so they belong better in
virdomainsnapshotobjlist.h (missed in commit 9b75154c).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

An upcoming patch will rework virDomainSnapshotObjList to be generic
for both snapshots and checkpoints; reduce the churn by adding a new
accessor virDomainSnapshotObjGetDef() which returns the
snapshot-specific definition even when the list is rewritten to
operate only on a base class, then using it at sites that that are
specific to snapshots.  Use VIR_STEAL_PTR when appropriate in the
affected lines.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

Rather than allowing a leaky abstraction where multiple drivers have
to open-code operations that update the relations in a
virDomainSnapshotObjList, it is better to add accessor functions so
that updates to relations are maintained closer to the internals.
This patch finishes the job started in the previous patch, by getting
rid of all direct access to nchildren, first_child, or sibling outside
of the lowest level functions, making it easier to refactor later on.

The lone new caller to virDomainSnapshotObjListSize() checks for a
return != 0, because it wants to handles errors (-1, only possible if
the hash table wasn't allocated) and existing snapshots (> 0) in the
same manner; we can drop the check for a current snapshot on the
grounds that there shouldn't be one if there are no snapshots.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

It is easier to track the current snapshot as part of the list of
snapshots. In particular, doing so lets us guarantee that the current
snapshot is cleared if that snapshot is removed from the list (rather
than depending on the caller to do so, and risking a use-after-free
problem, such as the one recently patched in 1db9d0ef).  This
requires the addition of several new accessor functions, as well as a
useful return type for virDomainSnapshotObjListRemove().  A few error
handling sites that were previously setting vm->current_snapshot =
NULL can now be dropped, because the previous function call has now
done it already.  Also, qemuDomainRevertToSnapshot() was setting the
current vm twice, so keep only the one used on the success path.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

snapshot_conf.h was mixing three separate types: the snapshot
definition, the snapshot object, and the snapshot object list.
Separate out the snapshot object list code into its own file, and
update includes for affected clients.

This is just code motion, but done in preparation of sharing a lot of
the object list code with checkpoints.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>