Back in the bad old days different device types required a different
qemu monitor call to detach them, and so an <interface type='hostdev'>
needed to call the function for detaching hostdevs, while other
<interface> types could be deleted as netdevs.

Times have changed, and *all* device types are detached by calling the
common function qemuDomainDeleteDevice(vm, alias), so we don't need to
differentiate between hostdev interfaces and the others for that
reason.

There are a few other netdev-specific functions called during
qemuDomainDetachNetDevice() (clearing bandwidth limits, stopping the
interface), but those turn into NOPs when type=hostdev, so they're
safe to call for type=hostdev.

The only thing that is different + not a NOP is the call to
virDomainAudit*() when qemuDomainDeleteDevice() fails, so if we add a
conditional for that small bit of code, we can eliminate the callout
from qemuDomainDetachNetDevice() to qemuDomainDetachThisDevice(),
which makes this function fit the desired pattern for merging with the
other detach functions, and paves the way to simplifying
qemuDomainDetachHostDevice() too.
Signed-off-by: NLaine Stump <laine@laine.org>
ACKed-by: NPeter Krempa <pkrempa@redhat.com>

qemuDomainDetachDiskDevice() is only called from one place. Moving the
contents of the function to that place makes
qemuDomainDetachDiskLive() more similar to the other Detach functions
called by the toplevel qemuDomainDetachDevice().

The goal is to make each of the device-type-specific functions do this:

  1) find the exact device
  2) do any device-specific validation
  3) do general validation
  4) do device-specific shutdown (only needed for net devices)
  5) do the common block of code to send device_del to qemu, then
     optionally wait for a corresponding DEVICE_DELETED event from
     qemu.

with the final aim being that only items 1 & 2 will remain in each
device-type-specific function, while 3 & 5 (which are the same for
almost every type) will be de-duplicated and moved to the toplevel
function that calls all of these (qemuDomainDetachDeviceLive(), which
will also contain a callout to the one instance of (4) (netdev).
Signed-off-by: NLaine Stump <laine@laine.org>
ACKed-by: NPeter Krempa <pkrempa@redhat.com>

qemuDomainDetachHostDevice() has a check at the end that calls
qemuDomainDetachNetDevice() in the case that the hostdev is actually a
Net device of type='hostdev'. A long time ago when device removal was
(supposedly but not actually) synchronous, this would cause some extra
code to be run prior to removing the device (e.g. restoring the original MAC
address of the device, undoing some sort of virtual port profile, etc).

For quite awhile now the device removal has been asynchronous, so that
"extra teardown" isn't handled by the detach function, but instead is
handled by the Remove function called at a later time. The result is
that when we call qemuDomainDetachNetDevice() from
qemuDomainDetachHostDevice(), it ends up just calling
qemuDomainDetachThisHostDevice() and returning, which is exactly what
we do for all other hostdevs anyway.

Based on that, remove the behavioral difference when parent.type ==
VIR_DOMAIN_DEVICE_NET, and just call qemuDomainDetachThisHostDevice()
for all hostdevs.
Signed-off-by: NLaine Stump <laine@laine.org>
ACKed-by: NPeter Krempa <pkrempa@redhat.com>

There are separate Detach functions for PCI, USB, SCSI, Vhost, and
Mediated hostdevs, but the functions are all 100% the same code,
except that the PCI function checks for the guest side of the device
being a PCI Multifunction device, while the other 4 check that the
device's alias != NULL.

The check for multifunction PCI devices should be done for *all*
devices that are connected to the PCI bus in the guest, not just PCI
hostdevs, and qemuIsMultiFunctionDevice() conveniently returns false
if the queried device doesn't connect with PCI, so it is safe to make
this check for all hostdev devices. (It also needs to be done for many
other device types, but that will be addressed in a future patch).

Likewise, since all hostdevs are detached by calling
qemuDomainDeleteDevice(), which requires the device's alias, checking
for a valid alias is a reasonable thing for PCI hostdevs too.
Signed-off-by: NLaine Stump <laine@laine.org>
ACKed-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

Having an InfoPtr named "dev" made my brain hurt. Renaming it to
"info" gives one less thing to confuse when looking at the code.
Signed-off-by: NLaine Stump <laine@laine.org>
ACKed-by: NPeter Krempa <pkrempa@redhat.com>

When support for hotplug/unplug of SCSI controllers was added way back
in December 2009 (commit da9d937b), unplug was handled by calling the
now-extinct function qemuMonitorRemovePCIDevice(), which required a
PCI address as an argument. At the same time, the idea of every device
in the config having a PCI address apparently was not yet fully
implemented, because the author of the patch including a check for a
valid PCI address in the device object.

These days, all PCI devices are guaranteed to have a valid PCI
address. But more important than that, we no longer detach devices by
PCI address, but instead use qemuDomainDeleteDevice(), which
identifies the device by its alias. So checking for a valid PCI
address is just pointless extra code that obscures the high level of
similarity between all the individual qemuDomainDetach*Device()
functions.
Signed-off-by: NLaine Stump <laine@laine.org>
ACKed-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

qemuDomainRemoveRNGDevice() calls qemuDomainDetachExtensionDevice().
According to commit 1d1e264f that added this code, it should not be
necessary to explicitly remove the zPCI extension device for a PCI
device during unplug, because "QEMU implements an unplug callback
which will unplug both PCI and zPCI device in a cascaded way". In
fact, no other devices call qemuDomainDetachExtensionDevice() during
their qemuDomainRemove*Device() function, so it should be removed from
qemuDomainRemoveRNGDevice as well.
Signed-off-by: NLaine Stump <laine@laine.org>
Reviewed-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NBoris Fiuczynski <fiuczy@linux.ibm.com>

qemuDomainDetachControllerDevice() calls
qemuDomainDetachExtensionDevice() when the controller type is
PCI. This is incorrect in multiple ways:

* Any code that tears down a device should be in the
  qemuDomainRemove*Device() function (which is called after libvirt
  gets a DEVICE_DELETED event from qemu indicating that the guest is
  finished with the device on its end. The qemuDomainDetach*Device()
  functions should only contain code that ensures the requested
  operation is valid, and sends the command to qemu to initiate the
  unplug.

* qemuDomainDetachExtensionDevice() is a function that applies to
  devices that plug into a PCI slot, *not* necessarily PCI controllers
  (which is what's being checked in the offending code). The proper
  way to check for this would be to see if the DeviceInfo for the
  controller device had a PCI address, not to check if the controller
  is a PCI controller (the code being removed was doing the latter).

* According to commit 1d1e264f that added this code (and other
  support for hotplugging zPCI devices on s390), it's not necessary to
  explicitly detach the zPCI device when unplugging a PCI device. To
  quote:

       There's no need to implement hot unplug for zPCI as QEMU
       implements an unplug callback which will unplug both PCI and
       zPCI device in a cascaded way.

  and the evidence bears this out - all the other uses of
  qemuDomainDetachExtensionDevice() (except one, which I believe is
  also in error, and is being removed in a separate patch) are only to
  remove the zPCI extension device in cases where it was successfully
  added, but there was some other failure later in the hotplug process
  (so there was no regular PCI device to remove and trigger removal of
  the zPCI extension device).

* PCI controllers are not hot pluggable, so this is dead code
  anyway. (The only controllers that can currently be
  hotplugged/unplugged are SCSI controllers).
Signed-off-by: NLaine Stump <laine@laine.org>
Reviewed-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NBoris Fiuczynski <fiuczy@linux.ibm.com>

After 7431b3eb libvirt requires "filter", "nat" and
"mangle" tables to exist for both IPv4 and IPv6. This fact was
missed in the news.xml and since we don't have any better place
to advertise that let's update old news.

This was refined in 686803a1 and since that is not released
yet create a new entry documenting the refinement.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

Had this been in place earlier, I would have avoided the bugs in
commit 0baf6945 and 55c2ab3e. Writing the test required me to extend
the power of virsh - creating enough snapshots to cause fanout
requires enough input in a single session that adding comments and
markers makes it easier to check that output is correct. It's still a
bit odd that with test:///default, reverting to a snapshot changes the
domain from running to paused (possibly a bug in how the test driver
copied from the qemu driver) - but the important part is that the test
is reproducible, and any future tweaks we make to snapshot code have
less chance of breaking successful command sequences.
Signed-off-by: NEric Blake <eblake@redhat.com>
Acked-by: NMichal Privoznik <mprivozn@redhat.com>

Since test:///default resets state on every connection, writing a test
that covers a sequence of commands must be done from a single
session. But if the test wants to exercise particular failure modes as
well as successes, it can be nice to leave witnesses in the stderr
stream immediately before and after the spot where the expected error
should be, to ensure the rest of the script is not causing errors.

Do this by adding an --err option.
Signed-off-by: NEric Blake <eblake@redhat.com>
Acked-by: NMichal Privoznik <mprivozn@redhat.com>

As the previous commit mentioned, argv mode (such as when you feed
virsh via stdin with <<\EOF instead of via a single shell argument)
didn't permit comments. Do this by treating any command name token
that starts with # as a comment which silently eats all remaining
arguments to the next newline or semicolon.

Note that batch mode recognizes unquoted # at the start of any word as
a command as part of the tokenizer, while this patch only treats # at
the start of the command word as a comment (any other # remaining by
the time vshCommandParse() is processing things was already quoted
during the tokenzier, and as such was probably intended as the actual
argument to the command word earlier in the line).

Now I can do something like:

$ virsh -c test:///default <<EOF
  # setup
  snapshot-create-as test s1
  snapshot-create-as test s2
  # check
  snapshot-list test --name
EOF
Signed-off-by: NEric Blake <eblake@redhat.com>
Acked-by: NMichal Privoznik <mprivozn@redhat.com>

Continuing from what I did in commit 4817dec0, now I want to write a
sequence that is self-documenting.  So I need comments :)

Now I can do something like:

$ virsh -c test:///default '
  # setup
  snapshot-create-as test s1
  snapshot-create-as test s2
  # check
  snapshot-list test --name
'

Note that this does NOT accept comments in argv mode, another patch
will tackle that.

(If I'm not careful, I might turn virsh into a full-fledged 'sh'
replacement? Here's hoping I don't go that far...)
Signed-off-by: NEric Blake <eblake@redhat.com>
Acked-by: NMichal Privoznik <mprivozn@redhat.com>

Commit 55c2ab3e accidentally introduced an infinite loop while
checking whether a redefined snapshot would cause an infinite loop in
chasing its parents back to a root.  Alas, 'make check' did not catch
it, so my next patch will be a testsuite improvement that would have
hung and prevented the bug from being checked in to begin with.
Signed-off-by: NEric Blake <eblake@redhat.com>
Acked-by: NMichal Privoznik <mprivozn@redhat.com>

In a case where we want to hotplug the following disk:

<disk type='file' device='disk'>
    (...)
    <address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>

In a QEMU guest that has a single OS disk, as follows:

<disk type='file' device='disk'>
    (...)
    <address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>

What happens is that the existing guest disk will receive the ID
'scsi0-0-0-0' due to how Libvirt calculate the alias based on
the address in qemu_alias.c, qemuAssignDeviceDiskAlias. When hotplugging
a disk that happens to have the same address, Libvirt will calculate
the same ID to it and attempt to device_add. QEMU will refuse it:

$ virsh attach-device ub1810 hp-disk-dup.xml
error: Failed to attach device from hp-disk-dup.xml
error: internal error: unable to execute QEMU command 'device_add': Duplicate ID 'scsi0-0-0-0' for device

And Libvirt follows it up with a cleanup code in qemuDomainAttachDiskGeneric
that ends up removing what supposedly is a faulty hotplugged disk but, in
this case, ends up being the original guest disk.

This patch adds an address verification for all attached devices, avoid
calling the driver attach() function using a device with duplicated address.
The change is done in virDomainDefCompatibleDevice when @action is equal
to VIR_DOMAIN_DEVICE_ACTION_ATTACH. The affected callers are:

- qemuDomainAttachDeviceLiveAndConfig, both LIVE and CONFIG cases;
- lxcDomainAttachDeviceFlags, both LIVE and CONFIG.

The check is done using the virDomainDefHasDeviceAddress, a generic
function that can check address duplicates for all supported device
types, not limiting just to DeviceDisk type.

After this patch, this is the result of the previous attach-device call:

$ ./run tools/virsh attach-device ub1810 hp-disk-dup.xml
error: Failed to attach device from hp-disk-dup.xml
error: Requested operation is not valid: Domain already contains a device with the same address
Reported-by: NSrikanth Aithal <bssrikanth@in.ibm.com>
Signed-off-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

Base macro to unify the actual testCompareXMLToArgv test calls
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

* ARG_CAPS_ARCH must be specified with ARG_CAPS_VER
* ARG_QEMU_CAPS shouldn't be specified with ARG_CAPS_*
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

Move DO_CAPS_TEST* qemuCaps init and all the associated setup
into testInfoSetArgs, adding ARG_CAPS_ARCH and ARG_CAPS_VER
options and using those to build the capsfile path locally
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

Make it an actual path and not a string prefix
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

These blocks are only triggered when updating from a libvirt version
less than 0.9.4, which was released in August 2011. I think it's been
long enough that we can say this upgrade path is unsupported without
an intermediate step.
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

Since Fedora 28 (our minimum supported build), ldconfig is called
automatically for us:

https://fedoraproject.org/wiki/Changes/Removing_ldconfig_scriptlets

These changes appear to be implemented for RHEL > 7 as well, so only
run ldconfig on RHEL7
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

We have tests for simple guests with graphics for basically
all other architectures, so it makes sense to include s390x
too.

The input file was generated by running

  $ virt-install \
    --name guest --os-variant fedora29 \
    --vcpus 4 --memory 4096 --disk size=5 \
    --graphics vnc \
    --print-xml

followed by minor tweaks, using a version of virt-manager
that includes commit 7b9de27a990f.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Acked-by: NMichal Privoznik <mprivozn@redhat.com>

As of commit db6c7070e25a, virt-manager will default to using
virtio-blk rather than virtio-scsi for aarch64/virt guests,
bringing them in line with other architectures. Update our test
case to reflect this change.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Acked-by: NMichal Privoznik <mprivozn@redhat.com>

This functions tries to add a domain moment (love the name!) onto
a list of domain moments. Firstly, it checks if another moment
with the same name already exists. Then, it creates an empty
moment (without initializing its definition) and tries to add the
moment onto the list dereferencing moment definition in that
process. If it succeeds (which it never can), only after that it
sets moment->def.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

Commit 3bd4ed46 introduced this element as required which
breaks backcompat for test driver. Let's make the element optional.
Reviewed-by: NErik Skultety <eskultet@redhat.com>
Signed-off-by: NNikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>

Commit d1a7c08e changed filter instantiation code to ignore MAC and IP
variables explicitly specified for filter binding. It just replaces
explicit values with values associated with the binding. Before the
commit virNWFilterCreateVarsFrom was used so that explicit value
take precedence. Let's bring old behavior back.

This is useful. For example if domain has two interfaces it makes
sense to list both mac adresses in MAC var of every interface
filterref. So that if guest make a bond of these interfaces
and start sending frames with one of the mac adresses from
both interfaces we can pass outgress traffic from both
interfaces too.
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
Signed-off-by: NNikolay Shirokovskiy <nshirokovskiy@virtuozzo.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>

The new code here very heavily resembles the code in
virDomainSnapshotObjList. There are still a couple of spots that are
tied a little too heavily to snapshots (the free function lacks a
polymorphic cleanup until we refactor code to use virObject; and an
upcoming patch will add internal VIR_DOMAIN_MOMENT_LIST flags to
replace the snapshot flag bits), but in general this is fairly close
to the state needed to add checkpoint lists.
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>

Pull out the common parts of virDomainSnapshotDef that will be reused
for virDomainCheckpointDef into a new base class.  Adjust all callers
that use the direct fields (some of it is churn that disappears when
the next patch refactors virDomainSnapshotObj; oh well...).

Someday, I hope to switch this type to be a subclass of virObject, but
that requires a more thorough audit of cleanup paths, and besides
minimal incremental changes are easier to review.

As for the choice of naming:
I promised my teenage daughter Evelyn that I'd give her credit for her
contribution to this commit. I asked her "What would be a good name
for a base class for DomainSnapshot and DomainCheckpoint". After
explaining what a base class was (using the classic OOB Square and
Circle inherit from Shape), she came up with "DomainMoment", which is
way better than my initial thought of "DomainPointInTime" or
"DomainPIT".
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>

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 starts the task with a single new function:
virDomainSnapshotMoveChildren(). The logic might not be immediately
obvious [okay, that's an understatement - the existing code uses black
magic ;-)], so here's an overview: The old code has an implicit for
loop around each call to qemuDomainSnapshotReparentChildren() by using
virDomainSnapshotForEachChild() (you'll need a wider context than
git's default of 3 lines to see that); the new code has a more visible
for loop. Then it helps if you realize that the code is making two
separate changes to each child object: STRDUP of the new parent name
prior to writing XML files (unchanged), and touching up the pointer to
the parent object (refactored); the end result is the same whether a
single pass made both changes (both in driver code), or whether it is
split into two passes making one change each (one in driver code, the
other in the new accessor).
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>

Rework the logic in qemuDomainSnapshotLoad() to set
vm->current_snapshot only once at the end of the loop, rather than
repeatedly querying it during the loop, to make it easier for the next
patch to use accessor functions rather than direct manipulation of
vm->current_snapshot.  When encountering multiple snapshots claiming
to be current (based on the presence of an <active>1</active> element
in the XML, which libvirt only outputs for internal use and not for
any public API), this changes behavior from warning only once and
running with no current snapshot, to instead warning on each duplicate
and selecting the last one encountered (which is arbitrary based on
readdir() ordering, but actually stands a fair chance of being the
most-recently created snapshot whether by timestamp or by the
propensity of humans to name things in ascending order).

Note that the code in question is only run by libvirtd when it first
starts, reading state from disk from the previous run into memory for
this run. Since the data resides somewhere that only libvirt should be
touching (typically /var/lib/libvirt/qemu/snapshot/*), it should be
clean.  So in the common case, the code touched here is unreachable.
But if someone is actually messing with files behind libvirt's back,
they deserve the change in behavior.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

The only use for the 'current' member of virDomainSnapshotDef was with
the PARSE/FORMAT_INTERNAL flag for controlling an internal-use
<active> element marking whether a particular snapshot definition was
current, and even then, only by the qemu driver on output, and by qemu
and test driver on input. But this duplicates vm->snapshot_current,
and gets in the way of potential simplifications to have qemu store a
single file for all snapshots rather than one file per snapshot.  Get
rid of the member by adding a bool* parameter during parse (ignored if
the PARSE_INTERNAL flag is not set), and by adding a new flag during
format (if FORMAT_INTERNAL is set, the value printed in <active>
depends on the new FORMAT_CURRENT).

Then update the qemu driver accordingly, which involves hoisting
assignments to vm->current_snapshot to occur prior to any point where
a snapshot XML file is written (although qemu kept
vm->current_snapshot and snapshot->def_current in sync by the end of
the function, they were not always identical in the middle of
functions, so the shuffling gets a bit interesting). Later patches
will clean up some of that confusing churn to vm->current_snapshot.

Note: even if later patches refactor qemu to no longer use
FORMAT_INTERNAL for output (by storing bulk snapshot XML instead), we
will always need PARSE_INTERNAL for input (because on upgrade, a new
libvirt still has to parse XML left from a previous libvirt).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

When a future patch converts virDomainSnapshotDef to be a virObject,
we need to be careful that converting VIR_FREE() to virObjectUnref()
does not result in double frees. Reorder the assignment of def into
the object to the point after object is in the hash table (as
otherwise the virHashAddEntry() error path would have a shot at
freeing def prematurely).
Suggested-by: NJohn Ferlan <ferlan@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>