The current virtlogd RPC protocol provides the ability to
handle log files associated with QEMU stdout/err. The log
protocol messages take the virt driver, domain name and
use that to form a log file path. This is quite restrictive
as it prevents us re-using the same RPC protocol messages
for logging to char device backends where the filename
can be arbitrarily user specified. It is also bad because
it means we have 2 separate locations which have to decide
on logfile name.

This change alters the RPC protocol so that we pass the
desired log file path along when opening the log file
initially. Now the virt driver is exclusively in charge
of deciding the log filename
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Define a new RPC protocol for the virtlogd daemon that provides
for handling of logs. The initial RPC method defined allows a
client to obtain a file handle to use for writing to a log
file for a guest domain. The file handle passed back will not
actually refer to the log file, but rather an anonymous pipe.
The virtlogd daemon will forward I/O between them, ensuring
file rotation happens when required.

Initially the log setup is hardcoded to cap log files at
128 KB, and keep 3 backups when rolling over, which gives
a max usage of 512 KB per guest.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Copy the virtlockd codebase across to form the initial virlogd
code. Simple search & replace of s/lock/log/ and gut the remote
protocol & dispatcher. This gives us a daemon that starts up
and listens for connections, but does nothing with them.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>