libnbd-release-notes-1.12 - Man Page

release notes for libnbd 1.12


These are the release notes for libnbd stable release 1.12. This describes the major changes since 1.10.

libnbd 1.12.0 was released on 24 February 2022.



Silent data corruption when using nbdcopy(1).

See the full announcement here:

If you find a security issue, please read SECURITY in the source (online here:  To find out about previous security issues in libnbd, see libnbd-security(3).

New APIs


Control whether libnbd clears the pread buffer to avoid leaking memory contents if the client does not properly handle errors.  These were added as part of the fix for CVE-2022-0485 (Eric Blake).


Control whether libnbd requests block size constraints from the server during negotiation (Eric Blake).

Enhancements to existing APIs

Error messages about incorrect URIs in nbd_connect_uri(3) have been improved to make common mistakes clearer for the user.


New syntax: nbdinfo [ CMD ... ] allowing you to query the properties of an NBD server directly.

nbdcopy(1) new --queue-size option to control the maximum size of the internal buffer (Nir Soffer).

nbdcopy(1) now names the source and destination handles to make it easier to understand debug output.


Adopt libvirt-ci's ci/gitlab.yml (Martin Kletzander).

Fix the OCaml extents example (thanks Laszlo Ersek).

Golang benchmarks were added to the test suite (Nir Soffer).

The large tests/errors.c test was split into about a dozen separate tests.  Also this adds a new test for checking server-side block size constraint error policy which was missing before.

Other improvements and bug fixes

New OCaml NBD.with_handle helper which ensures that NBD.close is always called even if the inner code throws an exception.

The OCaml bindings now consistently use the correct types for buffer sizes everywhere (Laszlo Ersek).

Several improvements and fixes to the golang bindings and tests.  The golang bindings have been relicensed to LGPLv2+ like the rest of the library and are now published as a golang module at (Nir Soffer).

The Python bindings no longer crash if you pass None in place of a buffer parameter.  In addition some memory leaks were fixed (Eric Blake).

Various memory leaks have been fixed when using the optional strict_mode settings (Eric Blake).

The performance of the internal vector library has been improved greatly and overflow is now handled correctly (Nir Soffer, Laszlo Ersek and Eric Blake).

Add simple_copy and aio_copy Golang examples (Nir Soffer).

Error handling was reviewed and fixed across many of the example programs and documentation (Eric Blake, Nir Soffer).

Simplify and optimize handling of the extents callback in Golang (Nir Soffer).

Golang AioBuffer was enhanced, making it safer to use, faster and adding documentation (Nir Soffer).


Document the limits on lengths and sizes of parameters to various APIs (Eric Blake).


You can now build programs that use the OCaml bindings of libnbd against the libnbd build directory instead of requiring libnbd to be installed (Laszlo Ersek).

Compatibility with OCaml 4.13.

Line locations in the state machine should be more accurate when stepping through with a debugger like gdb.

.editorconfig file can be used to help code formatting, see (Nir Soffer, Eric Blake).

MIN and MAX macros can be nested (thanks Eric Blake).

See Also



Eric Blake

Laszlo Ersek

Martin Kletzander

Nir Soffer

Richard W.M. Jones


This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

Referenced By


2022-09-27 libnbd-1.15.4