Licensing

Note that much of the vbox in this directory is LGPLv2-only.  Thus, it
cannot be linked into any software that also wants to use GPLv3+ code.
This readme file is:

Copyright (C) 2009, 2013 Red Hat, Inc.

Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.  This file is offered as-is,
without warranty of any kind.

    Explanation about the how multi-version support
    for VirtualBox libvirt driver is implemented.

Since VirtualBox adds multiple new features for each release, it is but
natural that the C API which VirtualBox exposes is volatile across
versions and thus needs a good mechanism to handle multiple versions
during runtime. The solution was something like this:

Firstly the file structure is as below:

vbox_CAPI_v2_2.h
vbox_XPCOMCGlue.h
vbox_XPCOMCGlue.c
These files are C API/glue code files directly taken from the
VirtualBox OSE source and is needed for C API to work as expected.

vbox_driver.h
vbox_driver.c
These files have the main logic for registering the virtualbox driver
with libvirt.

vbox_V2_2.c
The file which has version dependent changes and includes the template
file for given below for all of its functionality.

vbox_tmpl.c
The file contains all version specified codes. It implements the
vboxUniformedAPI for each vbox version.

vbox_common.c
The file implement the common driver, with the uniformed api which
defined in vbox_uniformed_api.h and implemented in vbox_tmpl.c

Now there would be a vbox_V*.c file (for eg: vbox_V2_2.c for V2.2) for
each major virtualbox version which would do some preprocessor magic
and include the template file (vbox_tmpl.c) in it for the functionality
it offers.