Instead of calling xmllint via a shell script, use our virXMLValidator
API to do it directly via libxml.

Split out the code for XML validation into a new function.

Split out all the code initializing the validator
to a separate function.

Split out the code cleaning up the validator.

Store all the data related to RNG validation in one structure to
allow splitting virXMLValidateAgainstSchema.

In commit 1e38ef72 the disk startup policy check was moved prior to the
call to virDomainObjSetDefTransient which dropped the disk from the
config rather than the def to be started which is a bug.

Additionally we'd not report the disk change event for this since the
disk aliases were not set at that point.

Finally 'volume' based disks would not work with startup policy too.

Fix it by moving it back after the definition is copied, aliases are
assigned and disk sources are translated.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1341415

One of the functions is returning always 0 and the second one uses
unnecessary labels.

qemuProcessStart does not unset the infrastructure that retrieves errors
from the qemu log file in case of migration. As this wasn't handled
properly in qemuDomainSaveImageStartVM we kept the logging context/fd
open for the lifetime of the VM rather than closing it after it's not
needed.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1325080

The configuration files are not directly executable as they don't have
as hash-bang line.

tap2 only handles 'aio', but not 'raw', which must be explicitly given:

XML:raw needs to be translated to XM:aio for 'tap' and 'tap2' Xen
drivers.

tap2 only handles 'aio', but not 'raw', which must be explicitly given:

| $ virsh domxml-to-native yyy.xml > yyy.xm
| $ xm new yyy.xm
| Error: tap:/srv/xen/xxx.img not a valid disk type
| $ sed -i -e 's/tap2:/&aio:/' yyy.xm
| $ xm new yyy.xm

Fix reading and writing "xen-xm" format for "tap2" by handling it the
same as "tap".

Note the start of migration of a qemu process to the VM log file for
possible debug purposes.

Use qemuDomainLogAppendMessage rather than attempting to open a new
logging context with file descriptors. The new approach allows to log
the message even if qemu is still running at that point which appens
during migration finish phase where qemuProcessStop is killing qemu.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1312188

Along with the virtlogd addition of the log file appending API implement
a helper for logging one-shot entries to the log file including the
fallback approach of using direct file access.

This will be used for noting the shutdown of the qemu proces and
possibly other actions such as VM migration and other critical VM
lifecycle events.

Implement the RPC dispatcher and caller for the new API.

For logging one-shot entries to the VM log file it's quite a waste to
hold open the file descriptor for logging that is provided by the
current API.

This new API will be ideal for logging one-shot entries to the file
e.g. at the point when we shut the VM down rather than having to add the
whole file-descriptor infrastructure.

Additionally this will allow to add the messages even after restart of
libvirtd since virtlogd doesn't allow to obtain a regular context with
filedescriptors while the VM is still active.

Document the return value of virRandomBytes as 0 or some errno value and
then make sure all callers make the proper checks.

This speeds up node_device_udev driver startup 11x.

Simplify the logic

Move out the code depending on HAVE_DECL_ETHTOOL_GFEATURES.

Split out the features that we probe via various ethtool commands
and ETHTOOL_GFLAGS.

Rename struct elem to virNetDevEthtoolFeatureCmd and move it
out of the function to allow reusing it.

The new flag was not added to virCheckFlags in commit '0d1c17aa' causing
a regression where VMs were not able to start.

Rather than intermixing the ATTRIBUTE_UNUSED - use HAVE_GNUTLS_CIPHER_ENCRYPT
for the whole function instead.

Filter out some subsystems we are not interested in.

Instead of the custom out and out_unlock.

Remove ret variables and labels from functions where there is no cleanup
to be done.

Introduce a validation callback for qemu and move checking of
min_guarantee to the new callback.

Now with the proper domain config validation infrastructure the check
can be moved to a place that doesn't make domains vanish.

Since it will not be called from outside of conf we can unexport it too
if we move it to the appropriate place.

Test suite change is necessary since the error will be reported sooner
now.

To avoid duplicating all the checks when starting a fresh VM from a
possibly unchecked config, call the domain def validator.

Validation of qemu process startup requires to know whether the process
is used for a fresh VM or whether it's reloaded from a
snapshot/migration. Pass this information in via a flag rather than
calculating it from a bunch of bools.

Similarly to the domain definition validator add a device validator. The
change to the prototype of the domain validator is necessary as
virDomainDeviceInfoIterateInternal requires a non-const pointer.

It's passed to all places along with the structure.