1297db7414
A problem encountered due to a bug in libpcap was reported to the
caller as:
An error occurred, but the cause is unknown
This was because the error had been logged in the DHCPSnoop
thread. The worker thread handling the API call to start a domain
spins up the DHCPSnoop thread which watches for dhcp packets with
libpcap, then uses virCondSignal() to notify the worker thread (which
has been waiting with virCondWait()). The worker thread knows that
there was an error (because threadStatus != THREAD_STATUS_OK), but the
error info had been stored in thread-specific storage for the other
thread, so the worker thread can only report that there was a failure,
but it doesn't know why.
The solution is to save the error that was logged (with
virErrorPreserveLast() into the object the is used to share info
between the threads, then we can set the error in the worker thread
using virErrorRestore().
In the case of the error I was looking at, this changed the "unknown"
message into:
internal error: pcap_setfilter: can't remove kernel filter:
Bad file descriptor
Signed-off-by: Laine Stump <laine@laine.org>
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: