guestfs-release-notes - libguestfs Release Notes


These release notes only cover the differences from the previous stable/dev branch split (1.30.0). For detailed changelogs, please see the git repository, or the ChangeLog file distributed in the tarball.

New features

New tools

The new virt-v2v-copy-to-local(1) tool is an ancillary tool for virt-v2v(1) allowing you to convert source guests that virt-v2v is unable to access directly.

New features in existing tools

Virt-customize knows how to write a random seed to CirrOS (Pino Toscano).

On Fedora, virt-customize runs dnf(8) with the --best flag, ensuring it always updates to the latest available packages.

Virt-builder now provides 32 bit Fedora templates.

Virt-builder and virt-customize --install option now works on 32 bit Fedora guests. Previously it would try to install 64 bit packages (Jan Sedlák).

Virt-builder can now fetch cloud images using Simple Streams v1.0 metadata (Pino Toscano).

Virt-builder can now fetch openSUSE cloud images out of the box (Cédric Bosdonnat).

Virt-customize will now use stronger (SHA-512) encrypted passwords by default on openSUSE ≥ 11 (Pino Toscano).

Virt-builder will now correctly handle output filenames containing colon characters (:), and will create temporary files in the libguestfs cache directory instead of defaulting to /tmp (Pino Toscano).

Virt-resize has a new --unknown-filesystems option to control what to do when asked to resize a filesystem that libguestfs doesn't know how to resize.

Virt-v2v now has an --in-place flag/mode, allowing in-place conversion of guests (Roman Kagan).

Virt-v2v has a --compressed option for creating compressed qcow2 output files.

Virt-v2v can now correctly get the VMware datacenter path (dcPath) from libvirt, instead of having to calculate it using an algorithm that occasionally got the wrong answer (Matthias Bolte, Tingting Zheng).

Virt-v2v now processes RAM sizes correctly for 64 bit guests when running on a 32 bit host.

Language bindings

In Perl and Python programs, the get_program_name API now returns the true program name, instead of the incorrect string perl or python.

The Python bindings can now be compiled against a different version of libguestfs, allowing the pip module to be built against any version of libguestfs (instead of requiring the pip module and libguestfs to have exactly the same version).

The quality of the Ruby rdoc (documentation) has been improved (Pino Toscano).

Perl scripts no longer hard-code the location of perl in the shebang line, but use env(1) to locate it instead (Pino Toscano).

In OCaml programs, the guestfs handle was incorrectly made into a global root, meaning it could never be garbage collected. If you didn't call the close function explicitly, the handle would not be closed until the whole program exited. This has now been fixed so handles will be garbage collected in the usual way. This changes the API of the OCaml function Guestfs.event_callback. Note that non-C language bindings are not covered by the libguestfs API/ABI guarantee, although we try hard not to change them, but in this case it was essential in order to fix this very serious bug.


Alpine Linux and the APK package manager, ALT Linux, Frugalware, and PLD Linux are now recognized (Pino Toscano).

If it exists, /etc/os-release will be preferred for inspecting Linux guests (Pino Toscano).

The correct kernel version is returned for Windows guests ≥ 10.


The large guestfs(3) man page has been split into several separate man pages: guestfs-hacking(1) guestfs-internals(1) guestfs-security(1). In the source tree, a new docs directory contains this documentation.

Architectures and platforms

Libguestfs now supports ARM 64 bit platforms with vGICv3.


See also guestfs-security(1).


This is not a vulnerability in libguestfs, but because we always give a virtio-serial port to each guest (since that is how guest-host communication happens), an escalation from the appliance to the host qemu process is possible. This could affect you if:

If you use sVirt to confine qemu, that would thwart some attacks.

Virt-customize permissions on .ssh, .ssh/authorized_keys

Previously when asked to inject an SSH key into a guest, virt-customize (hence virt-builder too) would create the .ssh directory and .ssh/authorized_keys file with too broad permissions, allowing other users to read. They are now created as 0700 and 0600 respectively, which is the same as the ssh-copy-id(1) utility.


New APIs


Get/set a per-handle identifier. The main effect of this is to change trace output from:

 libguestfs: trace: foo


 libguestfs: trace: ID: foo

making it easier to follow traces in multi-threaded programs, or where a program uses multiple handles (especially virt-v2v).


Return the minimum size of a filesystem (when shrunk). This supports ext2/3/4, XFS and btrfs, and can support other filesystem types in future (Maxim Perevedentsev).

Other API changes

guestfs_disk_create: add preallocation = off/metadata/full.

For raw, this allows off as a synonym for sparse (making it consistent with qcow2). For qcow2, this allows sparse as a synonym for off.

It also adds full, which corresponds to fully allocated, but uses posix_fallocate(3) for efficiency.

guestfs_tar_in: new xattrs, selinux, acl parameters.
guestfs_tar_out: new xattrs, selinux, acl parameters.

These extra parameters control whether extended attributes, SELinux contexts and/or POSIX ACLs are restored from / saved to tarballs.


The existing username and secret parameters can be used to supply authentication for iSCSI (Pino Toscano).

Build changes

The ./configure --enable-valgrind-daemon option has been removed.

You can no longer build libguestfs on RHEL 5-era (c.2007) machines. See the oldlinux branch if you need (limited) RHEL 5 support.

Virt-p2v can now be built on RHEL 6-era (c.2010) Linux distros.

OCaml ≥ 3.11 (released in 2008) is now required to build from git.

Building the Perl bindings now requires Module::Build (instead of ExtUtils::MakeMaker).

Builds should be faster (especially when incrementally rebuilding), because work was done to reduce build times.

Both OCaml and the OCaml findlib module are required if you need to run the generator at build time. Previously the build would have failed if findlib was not installed.

make check tests now run in parallel (within each test directory).

make install no longer installs OCaml bindtests.* files incorrectly.

make install can now be run twice. Previously it would fail on the second run.

make clean should now remove nearly every file that make creates.

A new make installcheck rule has been added, allowing the installed copy of libguestfs to be tested.


Some effort was put into minimizing the size of the appliance, which reduces temporary disk space and time needed by libguestfs handles.

The appliance now passes the NIC name to dhcpd, fixing hangs when running the appliance on some distros (Cédric Bosdonnat).

OCaml Guestfs.Errno is now generated (Pino Toscano).

In OCaml tools, common code now handles --debug-gc, --verbose and other common options (Roman Kagan, Pino Toscano).

The virt-v2v test harness allows us to boot the test guests at fixed dates in the past, ensuring that Windows reactivation doesn't kick in.

There is a new internal API for reading/writing a subprocess via a pipe from library code.

Used deheader program to remove unused #include directives.

In OCaml tools, the Char and String modules now implicitly reference the Common_utils.Char and Common_utils.String modules (instead of the ones from stdlib). The Common_utils modules contain a number of extra char/string utility functions, and also hide some unsafe functions in stdlib.

Many more virt-v2v tests will now be run even if you don't have rhsrvany and virtio-win installed (Roman Kagan).

The huge file has been split into several smaller files called m4/guestfs_*.m4.

The old tests/data and tests/guests directories have been moved to test-data/. This new top level directory carries all test data which is common, large and/or shared between multiple tests.

There is a new top level website/ directory containing the public website (or most of it).

The fuzz testing of inspection (tests/fuzz) has been removed.

Virt-p2v now saves the source physical machine dmesg output into the conversion server debug directory, making it simpler to debug cases of missing drivers, firmware etc.

Bugs fixed

set-label returns wrong error message when set the ext3/ext4 filesystem label

Add a Fedora 23 32-bit base image for virt-builder

virt-builder writes temporary files to /tmp

virt-resize does not copy logical partitions

virt-inspector returns version 6.3 for win10 images (should return 10.0)

virt-inspector --xpath segfault on attribute get

libguestfs can run commands with stdin not open (or worse still, connected to arbitrary guest-chosen random devices)

About compression option for qcow2

guestfish should be able to handle LVM thin layouts

DNF python programming error when run from virt-builder

inspection returns arch="unknown" for Windows guest if file command is not installed

Document permissions needed for non-admin users to use virt-v2v

RFE: virt-sparsify: make '--in-place' sparsification safe to abort (gracefully or ungracefully)

Virt-p2v client shouldn't present the vdsm option because it's not usable

virt-v2v fails to convert Windows raw image: error "device name is not a partition"

virt-builder: error: [file] is not a regular file in the guest

Simplestreams test fails: virt-builder: error: the value for the key 'size' is not an integer

guestfish copy-in command behaves oddly/unexpectedly with wildcards

python: Cannot compile pip module if installed libguestfs != pip guestfs version

Better diagnostic message when virbr0 doesn't exist

No warning shows when convert a win7 guest with AVG AntiVirus installed

virt-builder --ssh-inject doesn't set proper permissions on created files

RFE: V2V to check and warn user to disable group policy and anti virus on Windows guests

Wrong graphics protocal and video type set for guest after convert to rhev 3.6 by virt-v2v

extra slashes in vcenter URL confuses virt-v2v

[RHEV][V2V] virt-v2v ignores NIC if interface source/@network or source/@bridge is an empty string

virt-builder created Fedora 22 32bit disk image cannot be updated

virt-p2v no GUI mode:error opening control connection to $ip:22:unexpected …rompt

Option -oa preallocated -of qcow2 of virt-v2v didn't work efficiently

v2v: spaces need to be escaped as %20 in paths

Close all incoming ports on virt-p2v ISO

man virt-customize shows synopsis twice

mount-loop failed to setup loop device: No such file or directory

BUG: unable to handle kernel NULL pointer dereference at <addr> in function __blkg_lookup

virt-v2v should ignore bogus kernel entries in grub config

Unrelated info in fstab makes virt-v2v fail with unclear error info

virt-p2v: Using "Back" button causes output list to be repopulated multiple times

Wrong video driver is installed for rhel5.11 guest after conversion to libvirt

RFE: virt-builder creates qcow v3 images, add build option for qcow v2

File /etc/sysconfig/kernel isn't updated when convert XenPV guest with regular kernel installed

"lstatnslist" and "lstatlist" don't give an error if the API is used wrongly

koji spin-livecd cannot build a working live CD

mount-loop command fails: mount failed: Unknown error -1

set-label can only set <=127 bytes for btrfs and <=126 bytes for ntfs filesystem which not meet the help message. Also for ntfs it should give a warning message when the length >128 bytes

libvirt fails to shut down domain: could not destroy libvirt domain: Requested operation is not valid: domain is not running

mount-loop failed to setup loop device: No such file or directory


guestfs-examples(1), guestfs-faq(1), guestfs-performance(1), guestfs-recipes(1), guestfs-testing(1), guestfs(3), guestfish(1),


Richard W.M. Jones


Copyright (C) 2009-2023 Red Hat Inc.


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

This program 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 General Public License for more details.

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


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