When restarting VM (starting it just after it was shut down), it may
happen that previous `qubesdb-daemon` instance is still running - if VM
doesn't properly terminate the connection, dom0 part will not terminate
immediately, but at next alive check (every 10s). Such `qubesdb-daemon`,
when terminating, will remove pid file and socket file. In case of new
daemon already running it would be those of the new daemon, making the
whole QubesDB of this VM inaccessible for dom0 (`qubesdb-daemon` is
running, but its socket is removed).
To prevent this race, ensure that previous instance is terminated before
starting the new one.
There is no need to manually removing socket file, because if some stale
socket exists, it will be replaced by the new one when new
`qubesdb-daemon` starts up.
QubesOS/qubes-issues#1241
This makes easier to handle some corner cases. One of them is having
entry without `dir_path` defined. This may happen when migrating from R2
(using backup+restore or in-place) while some DisposableVM was running
(even if not included in the backup itself).
Fixesqubesos/qubes-issues#1124
Reported by @doncohen, thanks @wyory for providing more details.
This is required to create VMs in process of building Live system, where
libvirt isn't running.
Additionally there is no udev in the build environment, so needs to
manually create /dev/loop*p* based on sysfs info.
There were two bugs:
1. Firewall configuration wasn't copied during qvm-clone (it is in
separate file, so now it is included in vm.clone_disk_files).
2. Non-default firewall configuration wasn't stored in qubes.xml. This
means that initially DispVM got proper configuration (inherited from
calling VM), but if anything caused firewall reload (for example
starting another VM), the firewall rules was cleared to default state
(allow all).
Fixesqubesos/qubes-issues#1032
This way it gives more control over time synchronization to the VM. For
example Whonix VMs can decide to not use this mechanism. Also VM can
choose how that time will be set (chronyc call?). And finally it will be
possible to implement the same for other OS-es (Windows).
Additionally because of calling date as "localcmd" each time, instead of
once at the beginning, time synchronization is more accurrate now. If
some VM stall the time set call, other VMs time will no longer be
affected (but still synchronization will be delayed).
Most of them do not need GUI (especially those started from dom0), so
speed the things up a little (no need to wait for guid). But if some
service will need GUI access, there is "gui" parameter.
