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libnbd-release-notes-1.4 - Man Page

release notes for libnbd 1.4


These are the release notes for libnbd stable release 1.4. This describes the major changes since 1.2.

libnbd 1.4.0 was released on 25 August 2020.


There were no security issues found in this release.  If you find a security issue, please read SECURITY in the source (online here: https://gitlab.com/nbdkit/libnbd/blob/master/SECURITY).  To find out about previous security issues in libnbd, see libnbd-security(3).

New APIs


libnbd 1.4 adds a new “negotiating” state during NBD handshaking.  For backwards compatibility programs must request this before starting the connection by calling nbd_set_opt_mode(3).  You can find out if the connection is in this state by calling nbd_aio_is_negotiating(3).

For an in-depth description of how this extra state can be used to negotiate server options, see "CONTROLLING NEGOTIATION" in libnbd(3).


During the negotiating state, abort the connection.


During the negotiating state, complete the handshake.


During the negotiating state, request full information about the server export.


During the negotiating state, request the list of exports that the server provides.


Return the minimum, preferred or maximum block size constraints for requests sent to the server.


Return the canonical export name that the server defaults to.  This information may only be available if you call nbd_set_full_info(3) before connecting.


Return the optional text description of the current export.  This information may only be available if you call nbd_set_full_info(3) before connecting.


Enable extended information about exports from the server.

Thanks: Eric Blake for all of the new APIs.

New features

Bindings are now available in the Go programming language.

FreeBSD and OpenBSD are now fully supported platforms.

Bash tab completion is available for all of the command line tools.


Verbatim text in man pages that wrapped over several lines is now typeset correctly.

Links within the documentation have been enhanced, and are now checked for correctness.


New nbdcopy(1) tool lets you copy between an NBD server and a local file, or stream to and from an NBD server.

New nbdinfo(1) tool lets you print extended information about an NBD server’s exports (Eric Blake).


Test sockets are created in /tmp (instead of the local directory). This stops the test suite from failing if the local directory path is longer than the Unix domain socket maximum path length.

Other improvements and bug fixes

Trace messages have been improved: long strings are truncated, strings with non-printable characters are escaped, and lists of strings are printed.

The generator was split from a large single script into several small files.  To build from git the OCaml bytecode compiler (ocamlc(1)) is now required instead of the interpreter (ocaml(1)).

Long login names are supported in nbd_get_tls_username(3).

The handle name in nbdsh(1) is now set to nbdsh (instead of a randomly generated name).

Compatibility with OCaml 4.10.0 and 4.11.0.

Python AIO buffer adds a new is_zero method allowing Python clients to do sparsification when copying.

Compatibility with Python 3.9.

External C programs can now be compiled against libnbd’s build directory using ../libnbd/run ./configure.

Honggfuzz can be used as another external fuzzing option.

Fix compilation with glibc 2.32 which deprecates sys_errlist.

Many examples added or extended to demonstrate uses of the new APIs (Eric Blake).

See Also



Eric Blake

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


2024-06-25 libnbd-1.21.1