c34f11998e
Two new APIs are added so that security driver can lock and unlock paths it wishes to touch. These APIs are not for other drivers to call but security drivers (DAC and SELinux). That is the reason these APIs are not exposed through our libvirt_private.syms file. Three interesting things happen in this commit. The first is the global @lockManagerMutex. Unfortunately, this has to exist so that there is only one thread talking to virtlockd at a time. If there were more threads and one of them closed the connection prematurely, it would cause virtlockd killing libvirtd. Instead of complicated code that would handle that, let's have a mutex and keep the code simple. The second interesting thing is keeping connection open between lock and unlock API calls. This is achieved by duplicating client FD and keeping it open until unlock is called. This trick is used by regular disk content locking code when the FD is leaked to qemu. Finally, the third thing is polling implemented at client side. Since virtlockd has only one thread that handles locking requests, all it can do is either acquire lock or error out. Therefore, the polling has to be implemented in client. The polling is capped at 60 second timeout, which should be plenty since the metadata lock is held only for a fraction of a second. Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: John Ferlan <jferlan@redhat.com>
Libvirt API for virtualization
Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the website:
License
The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.1 (or later). See the files COPYING.LESSER
and COPYING for full license terms & conditions.
Installation
Libvirt uses the GNU Autotools build system, so in general can be built and installed with the usual commands. For example, to build in a manner that is suitable for installing as root, use:
$ ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var
$ make
$ sudo make install
While to build & install as an unprivileged user
$ ./configure --prefix=$HOME/usr
$ make
$ make install
The libvirt code relies on a large number of 3rd party libraries. These will
be detected during execution of the configure script and a summary printed
which lists any missing (optional) dependencies.
Contributing
The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
The libvirt project has two primary mailing lists:
- libvirt-users@redhat.com (for user discussions)
- libvir-list@redhat.com (for development only)
Further details on contacting the project are available on the website: