Linux gained new close_range() syscall (in v5.9) that allows closing a range of FDs in a single syscall. Ideally, we would use it to close FDs when spawning a process (e.g. via virCommand module). Glibc has close_range() wrapper over the syscall, which falls back to iterative closing of all FDs inside the range if running under older kernel. We don't wane that as in that case we might just close opened FDs (see Linux version of virCommandMassClose()). And musl doesn't have close_range() at all. Therefore, call syscall directly. Now, mass close of FDs happens in a fork()-ed off child. While it could detect whether the kernel does support close_range(), it has no way of passing this info back to the parent and thus each child would need to query it again and again. Since this can't change while we are running we can cache the information - hence virCloseRangeInit(). Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com> Reviewed-by: Kristina Hanicova <khanicov@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 2.0 (or later). See the files
COPYING.LESSER
and COPYING
for full license
terms & conditions.
Installation
Instructions on building and installing libvirt can be found on the website:
https://libvirt.org/compiling.html
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: