Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

17 files changed, 3400 insertions, 0 deletions

diff --git a/src/libudev/libudev-device-internal.h b/src/libudev/libudev-device-internal.h
new file mode 100644
index 0000000..437d431
--- /dev/null
+++ b/src/libudev/libudev-device-internal.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "libudev.h"
+#include "sd-device.h"
+
+struct udev_device;
+
+struct udev_device *udev_device_new(struct udev *udev, sd_device *device);
+sd_device *udev_device_get_sd_device(struct udev_device *udev_device);
diff --git a/src/libudev/libudev-device.c b/src/libudev/libudev-device.c
new file mode 100644
index 0000000..7b9f54c
--- /dev/null
+++ b/src/libudev/libudev-device.c
@@ -0,0 +1,895 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <ctype.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/sockios.h>
+#include <net/if.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "libudev.h"
+#include "sd-device.h"
+
+#include "alloc-util.h"
+#include "device-private.h"
+#include "device-util.h"
+#include "libudev-device-internal.h"
+#include "libudev-list-internal.h"
+#include "parse-util.h"
+#include "time-util.h"
+
+/**
+ * SECTION:libudev-device
+ * @short_description: kernel sys devices
+ *
+ * Representation of kernel sys devices. Devices are uniquely identified
+ * by their syspath, every device has exactly one path in the kernel sys
+ * filesystem. Devices usually belong to a kernel subsystem, and have
+ * a unique name inside that subsystem.
+ */
+
+/**
+ * udev_device:
+ *
+ * Opaque object representing one kernel sys device.
+ */
+struct udev_device {
+        struct udev *udev;
+
+        /* real device object */
+        sd_device *device;
+
+        /* legacy */
+        unsigned n_ref;
+
+        struct udev_device *parent;
+        bool parent_set;
+
+        struct udev_list *properties;
+        uint64_t properties_generation;
+        struct udev_list *all_tags, *current_tags;
+        uint64_t all_tags_generation, current_tags_generation;
+        struct udev_list *devlinks;
+        uint64_t devlinks_generation;
+        bool properties_read:1;
+        bool all_tags_read:1;
+        bool current_tags_read:1;
+        bool devlinks_read:1;
+        struct udev_list *sysattrs;
+        bool sysattrs_read;
+};
+
+/**
+ * udev_device_get_seqnum:
+ * @udev_device: udev device
+ *
+ * This is only valid if the device was received through a monitor. Devices read from
+ * sys do not have a sequence number.
+ *
+ * Returns: the kernel event sequence number, or 0 if there is no sequence number available.
+ **/
+_public_ unsigned long long udev_device_get_seqnum(struct udev_device *udev_device) {
+        uint64_t seqnum;
+
+        assert_return_errno(udev_device, 0, EINVAL);
+
+        if (sd_device_get_seqnum(udev_device->device, &seqnum) < 0)
+                return 0;
+
+        return seqnum;
+}
+
+/**
+ * udev_device_get_devnum:
+ * @udev_device: udev device
+ *
+ * Get the device major/minor number.
+ *
+ * Returns: the dev_t number.
+ **/
+_public_ dev_t udev_device_get_devnum(struct udev_device *udev_device) {
+        dev_t devnum;
+        int r;
+
+        assert_return_errno(udev_device, makedev(0, 0), EINVAL);
+
+        r = sd_device_get_devnum(udev_device->device, &devnum);
+        if (r == -ENOENT)
+                return makedev(0, 0);
+        if (r < 0)
+                return_with_errno(makedev(0, 0), r);
+
+        return devnum;
+}
+
+/**
+ * udev_device_get_driver:
+ * @udev_device: udev device
+ *
+ * Get the kernel driver name.
+ *
+ * Returns: the driver name string, or #NULL if there is no driver attached.
+ **/
+_public_ const char *udev_device_get_driver(struct udev_device *udev_device) {
+        const char *driver;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_driver(udev_device->device, &driver);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return driver;
+}
+
+/**
+ * udev_device_get_devtype:
+ * @udev_device: udev device
+ *
+ * Retrieve the devtype string of the udev device.
+ *
+ * Returns: the devtype name of the udev device, or #NULL if it cannot be determined
+ **/
+_public_ const char *udev_device_get_devtype(struct udev_device *udev_device) {
+        const char *devtype;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_devtype(udev_device->device, &devtype);
+        if (r == -ENOENT)
+                return NULL;
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return devtype;
+}
+
+/**
+ * udev_device_get_subsystem:
+ * @udev_device: udev device
+ *
+ * Retrieve the subsystem string of the udev device. The string does not
+ * contain any "/".
+ *
+ * Returns: the subsystem name of the udev device, or #NULL if it cannot be determined
+ **/
+_public_ const char *udev_device_get_subsystem(struct udev_device *udev_device) {
+        const char *subsystem;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_subsystem(udev_device->device, &subsystem);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return subsystem;
+}
+
+/**
+ * udev_device_get_property_value:
+ * @udev_device: udev device
+ * @key: property name
+ *
+ * Get the value of a given property.
+ *
+ * Returns: the property string, or #NULL if there is no such property.
+ **/
+_public_ const char *udev_device_get_property_value(struct udev_device *udev_device, const char *key) {
+        const char *value;
+        int r;
+
+        assert_return_errno(udev_device && key, NULL, EINVAL);
+
+        r = sd_device_get_property_value(udev_device->device, key, &value);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return value;
+}
+
+struct udev_device *udev_device_new(struct udev *udev, sd_device *device) {
+        _cleanup_(udev_list_freep) struct udev_list *properties = NULL, *all_tags = NULL, *current_tags = NULL, *sysattrs = NULL, *devlinks = NULL;
+        struct udev_device *udev_device;
+
+        assert(device);
+
+        properties = udev_list_new(true);
+        if (!properties)
+                return_with_errno(NULL, ENOMEM);
+        all_tags = udev_list_new(true);
+        if (!all_tags)
+                return_with_errno(NULL, ENOMEM);
+        current_tags = udev_list_new(true);
+        if (!current_tags)
+                return_with_errno(NULL, ENOMEM);
+        sysattrs = udev_list_new(true);
+        if (!sysattrs)
+                return_with_errno(NULL, ENOMEM);
+        devlinks = udev_list_new(true);
+        if (!devlinks)
+                return_with_errno(NULL, ENOMEM);
+
+        udev_device = new(struct udev_device, 1);
+        if (!udev_device)
+                return_with_errno(NULL, ENOMEM);
+
+        *udev_device = (struct udev_device) {
+                .n_ref = 1,
+                .udev = udev,
+                .device = sd_device_ref(device),
+                .properties = TAKE_PTR(properties),
+                .all_tags = TAKE_PTR(all_tags),
+                .current_tags = TAKE_PTR(current_tags),
+                .sysattrs = TAKE_PTR(sysattrs),
+                .devlinks = TAKE_PTR(devlinks),
+        };
+
+        return udev_device;
+}
+
+/**
+ * udev_device_new_from_syspath:
+ * @udev: udev library context
+ * @syspath: sys device path including sys directory
+ *
+ * Create new udev device, and fill in information from the sys
+ * device and the udev database entry. The syspath is the absolute
+ * path to the device, including the sys mount point.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev device.
+ *
+ * Returns: a new udev device, or #NULL, if it does not exist
+ **/
+_public_ struct udev_device *udev_device_new_from_syspath(struct udev *udev, const char *syspath) {
+        _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+        int r;
+
+        r = sd_device_new_from_syspath(&device, syspath);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return udev_device_new(udev, device);
+}
+
+/**
+ * udev_device_new_from_devnum:
+ * @udev: udev library context
+ * @type: char or block device
+ * @devnum: device major/minor number
+ *
+ * Create new udev device, and fill in information from the sys
+ * device and the udev database entry. The device is looked-up
+ * by its major/minor number and type. Character and block device
+ * numbers are not unique across the two types.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev device.
+ *
+ * Returns: a new udev device, or #NULL, if it does not exist
+ **/
+_public_ struct udev_device *udev_device_new_from_devnum(struct udev *udev, char type, dev_t devnum) {
+        _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+        int r;
+
+        r = sd_device_new_from_devnum(&device, type, devnum);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return udev_device_new(udev, device);
+}
+
+/**
+ * udev_device_new_from_device_id:
+ * @udev: udev library context
+ * @id: text string identifying a kernel device
+ *
+ * Create new udev device, and fill in information from the sys
+ * device and the udev database entry. The device is looked-up
+ * by a special string:
+ *   b8:2          - block device major:minor
+ *   c128:1        - char device major:minor
+ *   n3            - network device ifindex
+ *   +sound:card29 - kernel driver core subsystem:device name
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev device.
+ *
+ * Returns: a new udev device, or #NULL, if it does not exist
+ **/
+_public_ struct udev_device *udev_device_new_from_device_id(struct udev *udev, const char *id) {
+        _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+        int r;
+
+        r = sd_device_new_from_device_id(&device, id);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return udev_device_new(udev, device);
+}
+
+/**
+ * udev_device_new_from_subsystem_sysname:
+ * @udev: udev library context
+ * @subsystem: the subsystem of the device
+ * @sysname: the name of the device
+ *
+ * Create new udev device, and fill in information from the sys device
+ * and the udev database entry. The device is looked up by the subsystem
+ * and name string of the device, like "mem" / "zero", or "block" / "sda".
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev device.
+ *
+ * Returns: a new udev device, or #NULL, if it does not exist
+ **/
+_public_ struct udev_device *udev_device_new_from_subsystem_sysname(struct udev *udev, const char *subsystem, const char *sysname) {
+        _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+        int r;
+
+        r = sd_device_new_from_subsystem_sysname(&device, subsystem, sysname);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return udev_device_new(udev, device);
+}
+
+/**
+ * udev_device_new_from_environment
+ * @udev: udev library context
+ *
+ * Create new udev device, and fill in information from the
+ * current process environment. This only works reliably if
+ * the process is called from a udev rule. It is usually used
+ * for tools executed from IMPORT= rules.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev device.
+ *
+ * Returns: a new udev device, or #NULL, if it does not exist
+ **/
+_public_ struct udev_device *udev_device_new_from_environment(struct udev *udev) {
+        _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+        int r;
+
+        r = device_new_from_strv(&device, environ);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return udev_device_new(udev, device);
+}
+
+static struct udev_device *device_new_from_parent(struct udev_device *child) {
+        sd_device *parent;
+        int r;
+
+        assert_return_errno(child, NULL, EINVAL);
+
+        r = sd_device_get_parent(child->device, &parent);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return udev_device_new(child->udev, parent);
+}
+
+/**
+ * udev_device_get_parent:
+ * @udev_device: the device to start searching from
+ *
+ * Find the next parent device, and fill in information from the sys
+ * device and the udev database entry.
+ *
+ * Returned device is not referenced. It is attached to the child
+ * device, and will be cleaned up when the child device is cleaned up.
+ *
+ * It is not necessarily just the upper level directory, empty or not
+ * recognized sys directories are ignored.
+ *
+ * It can be called as many times as needed, without caring about
+ * references.
+ *
+ * Returns: a new udev device, or #NULL, if it no parent exist.
+ **/
+_public_ struct udev_device *udev_device_get_parent(struct udev_device *udev_device) {
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        if (!udev_device->parent_set) {
+                udev_device->parent_set = true;
+                udev_device->parent = device_new_from_parent(udev_device);
+        }
+
+        /* TODO: errno will differ here in case parent == NULL */
+        return udev_device->parent;
+}
+
+/**
+ * udev_device_get_parent_with_subsystem_devtype:
+ * @udev_device: udev device to start searching from
+ * @subsystem: the subsystem of the device
+ * @devtype: the type (DEVTYPE) of the device
+ *
+ * Find the next parent device, with a matching subsystem and devtype
+ * value, and fill in information from the sys device and the udev
+ * database entry.
+ *
+ * If devtype is #NULL, only subsystem is checked, and any devtype will
+ * match.
+ *
+ * Returned device is not referenced. It is attached to the child
+ * device, and will be cleaned up when the child device is cleaned up.
+ *
+ * It can be called as many times as needed, without caring about
+ * references.
+ *
+ * Returns: a new udev device, or #NULL if no matching parent exists.
+ **/
+_public_ struct udev_device *udev_device_get_parent_with_subsystem_devtype(struct udev_device *udev_device, const char *subsystem, const char *devtype) {
+        sd_device *parent;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        /* this relies on the fact that finding the subdevice of a parent or the
+           parent of a subdevice commute */
+
+        /* first find the correct sd_device */
+        r = sd_device_get_parent_with_subsystem_devtype(udev_device->device, subsystem, devtype, &parent);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        /* then walk the chain of udev_device parents until the corresponding
+           one is found */
+        while ((udev_device = udev_device_get_parent(udev_device)))
+                if (udev_device->device == parent)
+                        return udev_device;
+
+        return_with_errno(NULL, ENOENT);
+}
+
+/**
+ * udev_device_get_udev:
+ * @udev_device: udev device
+ *
+ * Retrieve the udev library context the device was created with.
+ *
+ * Returns: the udev library context
+ **/
+_public_ struct udev *udev_device_get_udev(struct udev_device *udev_device) {
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        return udev_device->udev;
+}
+
+static struct udev_device *udev_device_free(struct udev_device *udev_device) {
+        assert(udev_device);
+
+        sd_device_unref(udev_device->device);
+        udev_device_unref(udev_device->parent);
+
+        udev_list_free(udev_device->properties);
+        udev_list_free(udev_device->sysattrs);
+        udev_list_free(udev_device->all_tags);
+        udev_list_free(udev_device->current_tags);
+        udev_list_free(udev_device->devlinks);
+
+        return mfree(udev_device);
+}
+
+/**
+ * udev_device_ref:
+ * @udev_device: udev device
+ *
+ * Take a reference of a udev device.
+ *
+ * Returns: the passed udev device
+ **/
+
+/**
+ * udev_device_unref:
+ * @udev_device: udev device
+ *
+ * Drop a reference of a udev device. If the refcount reaches zero,
+ * the resources of the device will be released.
+ *
+ * Returns: #NULL
+ **/
+DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(struct udev_device, udev_device, udev_device_free);
+
+/**
+ * udev_device_get_devpath:
+ * @udev_device: udev device
+ *
+ * Retrieve the kernel devpath value of the udev device. The path
+ * does not contain the sys mount point, and starts with a '/'.
+ *
+ * Returns: the devpath of the udev device
+ **/
+_public_ const char *udev_device_get_devpath(struct udev_device *udev_device) {
+        const char *devpath;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_devpath(udev_device->device, &devpath);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return devpath;
+}
+
+/**
+ * udev_device_get_syspath:
+ * @udev_device: udev device
+ *
+ * Retrieve the sys path of the udev device. The path is an
+ * absolute path and starts with the sys mount point.
+ *
+ * Returns: the sys path of the udev device
+ **/
+_public_ const char *udev_device_get_syspath(struct udev_device *udev_device) {
+        const char *syspath;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_syspath(udev_device->device, &syspath);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return syspath;
+}
+
+/**
+ * udev_device_get_sysname:
+ * @udev_device: udev device
+ *
+ * Get the kernel device name in /sys.
+ *
+ * Returns: the name string of the device
+ **/
+_public_ const char *udev_device_get_sysname(struct udev_device *udev_device) {
+        const char *sysname;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_sysname(udev_device->device, &sysname);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return sysname;
+}
+
+/**
+ * udev_device_get_sysnum:
+ * @udev_device: udev device
+ *
+ * Get the instance number of the device.
+ *
+ * Returns: the trailing number string of the device name
+ **/
+_public_ const char *udev_device_get_sysnum(struct udev_device *udev_device) {
+        const char *sysnum;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_sysnum(udev_device->device, &sysnum);
+        if (r == -ENOENT)
+                return NULL;
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return sysnum;
+}
+
+/**
+ * udev_device_get_devnode:
+ * @udev_device: udev device
+ *
+ * Retrieve the device node file name belonging to the udev device.
+ * The path is an absolute path, and starts with the device directory.
+ *
+ * Returns: the device node file name of the udev device, or #NULL if no device node exists
+ **/
+_public_ const char *udev_device_get_devnode(struct udev_device *udev_device) {
+        const char *devnode;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_devname(udev_device->device, &devnode);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return devnode;
+}
+
+/**
+ * udev_device_get_devlinks_list_entry:
+ * @udev_device: udev device
+ *
+ * Retrieve the list of device links pointing to the device file of
+ * the udev device. The next list entry can be retrieved with
+ * udev_list_entry_get_next(), which returns #NULL if no more entries exist.
+ * The devlink path can be retrieved from the list entry by
+ * udev_list_entry_get_name(). The path is an absolute path, and starts with
+ * the device directory.
+ *
+ * Returns: the first entry of the device node link list
+ **/
+_public_ struct udev_list_entry *udev_device_get_devlinks_list_entry(struct udev_device *udev_device) {
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        if (device_get_devlinks_generation(udev_device->device) != udev_device->devlinks_generation ||
+            !udev_device->devlinks_read) {
+                udev_list_cleanup(udev_device->devlinks);
+
+                FOREACH_DEVICE_DEVLINK(udev_device->device, devlink)
+                        if (!udev_list_entry_add(udev_device->devlinks, devlink, NULL))
+                                return_with_errno(NULL, ENOMEM);
+
+                udev_device->devlinks_read = true;
+                udev_device->devlinks_generation = device_get_devlinks_generation(udev_device->device);
+        }
+
+        return udev_list_get_entry(udev_device->devlinks);
+}
+
+/**
+ * udev_device_get_event_properties_entry:
+ * @udev_device: udev device
+ *
+ * Retrieve the list of key/value device properties of the udev
+ * device. The next list entry can be retrieved with udev_list_entry_get_next(),
+ * which returns #NULL if no more entries exist. The property name
+ * can be retrieved from the list entry by udev_list_entry_get_name(),
+ * the property value by udev_list_entry_get_value().
+ *
+ * Returns: the first entry of the property list
+ **/
+_public_ struct udev_list_entry *udev_device_get_properties_list_entry(struct udev_device *udev_device) {
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        if (device_get_properties_generation(udev_device->device) != udev_device->properties_generation ||
+            !udev_device->properties_read) {
+                udev_list_cleanup(udev_device->properties);
+
+                FOREACH_DEVICE_PROPERTY(udev_device->device, key, value)
+                        if (!udev_list_entry_add(udev_device->properties, key, value))
+                                return_with_errno(NULL, ENOMEM);
+
+                udev_device->properties_read = true;
+                udev_device->properties_generation = device_get_properties_generation(udev_device->device);
+        }
+
+        return udev_list_get_entry(udev_device->properties);
+}
+
+/**
+ * udev_device_get_action:
+ * @udev_device: udev device
+ *
+ * This is only valid if the device was received through a monitor. Devices read from
+ * sys do not have an action string. Usual actions are: add, remove, change, move,
+ * online, offline.
+ *
+ * Returns: the kernel action value, or #NULL if there is no action value available.
+ **/
+_public_ const char *udev_device_get_action(struct udev_device *udev_device) {
+        sd_device_action_t action;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        if (sd_device_get_action(udev_device->device, &action) < 0)
+                return NULL;
+
+        return device_action_to_string(action);
+}
+
+/**
+ * udev_device_get_usec_since_initialized:
+ * @udev_device: udev device
+ *
+ * Return the number of microseconds passed since udev set up the
+ * device for the first time.
+ *
+ * This is only implemented for devices with need to store properties
+ * in the udev database. All other devices return 0 here.
+ *
+ * Returns: the number of microseconds since the device was first seen.
+ **/
+_public_ unsigned long long int udev_device_get_usec_since_initialized(struct udev_device *udev_device) {
+        usec_t ts;
+        int r;
+
+        assert_return(udev_device, -EINVAL);
+
+        r = sd_device_get_usec_since_initialized(udev_device->device, &ts);
+        if (r < 0)
+                return_with_errno(0, r);
+
+        return ts;
+}
+
+/**
+ * udev_device_get_sysattr_value:
+ * @udev_device: udev device
+ * @sysattr: attribute name
+ *
+ * The retrieved value is cached in the device. Repeated calls will return the same
+ * value and not open the attribute again.
+ *
+ * Returns: the content of a sys attribute file, or #NULL if there is no sys attribute value.
+ **/
+_public_ const char *udev_device_get_sysattr_value(struct udev_device *udev_device, const char *sysattr) {
+        const char *value;
+        int r;
+
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        r = sd_device_get_sysattr_value(udev_device->device, sysattr, &value);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return value;
+}
+
+/**
+ * udev_device_set_sysattr_value:
+ * @udev_device: udev device
+ * @sysattr: attribute name
+ * @value: new value to be set
+ *
+ * Update the contents of the sys attribute and the cached value of the device.
+ *
+ * Returns: Negative error code on failure or 0 on success.
+ **/
+_public_ int udev_device_set_sysattr_value(struct udev_device *udev_device, const char *sysattr, const char *value) {
+        int r;
+
+        assert_return(udev_device, -EINVAL);
+
+        r = sd_device_set_sysattr_value(udev_device->device, sysattr, value);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+/**
+ * udev_device_get_sysattr_list_entry:
+ * @udev_device: udev device
+ *
+ * Retrieve the list of available sysattrs, with value being empty;
+ * This just return all available sysfs attributes for a particular
+ * device without reading their values.
+ *
+ * Returns: the first entry of the property list
+ **/
+_public_ struct udev_list_entry *udev_device_get_sysattr_list_entry(struct udev_device *udev_device) {
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        if (!udev_device->sysattrs_read) {
+                udev_list_cleanup(udev_device->sysattrs);
+
+                FOREACH_DEVICE_SYSATTR(udev_device->device, sysattr)
+                        if (!udev_list_entry_add(udev_device->sysattrs, sysattr, NULL))
+                                return_with_errno(NULL, ENOMEM);
+
+                udev_device->sysattrs_read = true;
+        }
+
+        return udev_list_get_entry(udev_device->sysattrs);
+}
+
+/**
+ * udev_device_get_is_initialized:
+ * @udev_device: udev device
+ *
+ * Check if udev has already handled the device and has set up
+ * device node permissions and context, or has renamed a network
+ * device.
+ *
+ * This is only implemented for devices with a device node
+ * or network interfaces. All other devices return 1 here.
+ *
+ * Returns: 1 if the device is set up. 0 otherwise.
+ **/
+_public_ int udev_device_get_is_initialized(struct udev_device *udev_device) {
+        int r;
+
+        assert_return(udev_device, -EINVAL);
+
+        r = sd_device_get_is_initialized(udev_device->device);
+        if (r < 0)
+                return_with_errno(0, r);
+
+        return r;
+}
+
+/**
+ * udev_device_get_tags_list_entry:
+ * @udev_device: udev device
+ *
+ * Retrieve the list of tags attached to the udev device. The next
+ * list entry can be retrieved with udev_list_entry_get_next(),
+ * which returns #NULL if no more entries exist. The tag string
+ * can be retrieved from the list entry by udev_list_entry_get_name().
+ *
+ * Returns: the first entry of the tag list
+ **/
+_public_ struct udev_list_entry *udev_device_get_tags_list_entry(struct udev_device *udev_device) {
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        if (device_get_tags_generation(udev_device->device) != udev_device->all_tags_generation ||
+            !udev_device->all_tags_read) {
+                udev_list_cleanup(udev_device->all_tags);
+
+                FOREACH_DEVICE_TAG(udev_device->device, tag)
+                        if (!udev_list_entry_add(udev_device->all_tags, tag, NULL))
+                                return_with_errno(NULL, ENOMEM);
+
+                udev_device->all_tags_read = true;
+                udev_device->all_tags_generation = device_get_tags_generation(udev_device->device);
+        }
+
+        return udev_list_get_entry(udev_device->all_tags);
+}
+
+_public_ struct udev_list_entry *udev_device_get_current_tags_list_entry(struct udev_device *udev_device) {
+        assert_return_errno(udev_device, NULL, EINVAL);
+
+        if (device_get_tags_generation(udev_device->device) != udev_device->current_tags_generation ||
+            !udev_device->current_tags_read) {
+                udev_list_cleanup(udev_device->current_tags);
+
+                FOREACH_DEVICE_CURRENT_TAG(udev_device->device, tag)
+                        if (!udev_list_entry_add(udev_device->current_tags, tag, NULL))
+                                return_with_errno(NULL, ENOMEM);
+
+                udev_device->current_tags_read = true;
+                udev_device->current_tags_generation = device_get_tags_generation(udev_device->device);
+        }
+
+        return udev_list_get_entry(udev_device->current_tags);
+}
+
+/**
+ * udev_device_has_tag:
+ * @udev_device: udev device
+ * @tag: tag name
+ *
+ * Check if a given device has a certain tag associated.
+ *
+ * Returns: 1 if the tag is found. 0 otherwise.
+ **/
+_public_ int udev_device_has_tag(struct udev_device *udev_device, const char *tag) {
+        assert_return(udev_device, 0);
+
+        return sd_device_has_tag(udev_device->device, tag) > 0;
+}
+
+_public_ int udev_device_has_current_tag(struct udev_device *udev_device, const char *tag) {
+        assert_return(udev_device, 0);
+
+        return sd_device_has_current_tag(udev_device->device, tag) > 0;
+}
+
+sd_device *udev_device_get_sd_device(struct udev_device *udev_device) {
+        assert(udev_device);
+
+        return udev_device->device;
+}
diff --git a/src/libudev/libudev-enumerate.c b/src/libudev/libudev-enumerate.c
new file mode 100644
index 0000000..d71a31c
--- /dev/null
+++ b/src/libudev/libudev-enumerate.c
@@ -0,0 +1,458 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <dirent.h>
+#include <errno.h>
+#include <fnmatch.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#include "libudev.h"
+#include "sd-device.h"
+
+#include "alloc-util.h"
+#include "device-enumerator-private.h"
+#include "device-util.h"
+#include "libudev-device-internal.h"
+#include "libudev-list-internal.h"
+
+/**
+ * SECTION:libudev-enumerate
+ * @short_description: lookup and sort sys devices
+ *
+ * Lookup devices in the sys filesystem, filter devices by properties,
+ * and return a sorted list of devices.
+ */
+
+/**
+ * udev_enumerate:
+ *
+ * Opaque object representing one device lookup/sort context.
+ */
+struct udev_enumerate {
+        struct udev *udev;
+        unsigned n_ref;
+        struct udev_list *devices_list;
+        bool devices_uptodate:1;
+
+        sd_device_enumerator *enumerator;
+};
+
+/**
+ * udev_enumerate_new:
+ * @udev: udev library context
+ *
+ * Create an enumeration context to scan /sys.
+ *
+ * Returns: an enumeration context.
+ **/
+_public_ struct udev_enumerate *udev_enumerate_new(struct udev *udev) {
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        _cleanup_(udev_list_freep) struct udev_list *list = NULL;
+        struct udev_enumerate *udev_enumerate;
+        int r;
+
+        r = sd_device_enumerator_new(&e);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        r = sd_device_enumerator_allow_uninitialized(e);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        list = udev_list_new(false);
+        if (!list)
+                return_with_errno(NULL, ENOMEM);
+
+        udev_enumerate = new(struct udev_enumerate, 1);
+        if (!udev_enumerate)
+                return_with_errno(NULL, ENOMEM);
+
+        *udev_enumerate = (struct udev_enumerate) {
+                .udev = udev,
+                .n_ref = 1,
+                .enumerator = TAKE_PTR(e),
+                .devices_list = TAKE_PTR(list),
+        };
+
+        return udev_enumerate;
+}
+
+static struct udev_enumerate *udev_enumerate_free(struct udev_enumerate *udev_enumerate) {
+        assert(udev_enumerate);
+
+        udev_list_free(udev_enumerate->devices_list);
+        sd_device_enumerator_unref(udev_enumerate->enumerator);
+        return mfree(udev_enumerate);
+}
+
+/**
+ * udev_enumerate_ref:
+ * @udev_enumerate: context
+ *
+ * Take a reference of an enumeration context.
+ *
+ * Returns: the passed enumeration context
+ **/
+
+/**
+ * udev_enumerate_unref:
+ * @udev_enumerate: context
+ *
+ * Drop a reference of an enumeration context. If the refcount reaches zero,
+ * all resources of the enumeration context will be released.
+ *
+ * Returns: #NULL
+ **/
+DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(struct udev_enumerate, udev_enumerate, udev_enumerate_free);
+
+/**
+ * udev_enumerate_get_udev:
+ * @udev_enumerate: context
+ *
+ * Get the udev library context.
+ *
+ * Returns: a pointer to the context.
+ */
+_public_ struct udev *udev_enumerate_get_udev(struct udev_enumerate *udev_enumerate) {
+        assert_return_errno(udev_enumerate, NULL, EINVAL);
+
+        return udev_enumerate->udev;
+}
+
+/**
+ * udev_enumerate_get_list_entry:
+ * @udev_enumerate: context
+ *
+ * Get the first entry of the sorted list of device paths.
+ *
+ * Returns: a udev_list_entry.
+ */
+_public_ struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *udev_enumerate) {
+        struct udev_list_entry *e;
+
+        assert_return_errno(udev_enumerate, NULL, EINVAL);
+
+        if (!udev_enumerate->devices_uptodate) {
+                sd_device *device;
+
+                udev_list_cleanup(udev_enumerate->devices_list);
+
+                FOREACH_DEVICE_AND_SUBSYSTEM(udev_enumerate->enumerator, device) {
+                        const char *syspath;
+                        int r;
+
+                        r = sd_device_get_syspath(device, &syspath);
+                        if (r < 0)
+                                return_with_errno(NULL, r);
+
+                        if (!udev_list_entry_add(udev_enumerate->devices_list, syspath, NULL))
+                                return_with_errno(NULL, ENOMEM);
+                }
+
+                udev_enumerate->devices_uptodate = true;
+        }
+
+        e = udev_list_get_entry(udev_enumerate->devices_list);
+        if (!e)
+                return_with_errno(NULL, ENODATA);
+
+        return e;
+}
+
+/**
+ * udev_enumerate_add_match_subsystem:
+ * @udev_enumerate: context
+ * @subsystem: filter for a subsystem of the device to include in the list
+ *
+ * Match only devices belonging to a certain kernel subsystem.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_match_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!subsystem)
+                return 0;
+
+        r = sd_device_enumerator_add_match_subsystem(udev_enumerate->enumerator, subsystem, true);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_nomatch_subsystem:
+ * @udev_enumerate: context
+ * @subsystem: filter for a subsystem of the device to exclude from the list
+ *
+ * Match only devices not belonging to a certain kernel subsystem.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_nomatch_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!subsystem)
+                return 0;
+
+        r = sd_device_enumerator_add_match_subsystem(udev_enumerate->enumerator, subsystem, false);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_match_sysattr:
+ * @udev_enumerate: context
+ * @sysattr: filter for a sys attribute at the device to include in the list
+ * @value: optional value of the sys attribute
+ *
+ * Match only devices with a certain /sys device attribute.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_match_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!sysattr)
+                return 0;
+
+        r = sd_device_enumerator_add_match_sysattr(udev_enumerate->enumerator, sysattr, value, true);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_nomatch_sysattr:
+ * @udev_enumerate: context
+ * @sysattr: filter for a sys attribute at the device to exclude from the list
+ * @value: optional value of the sys attribute
+ *
+ * Match only devices not having a certain /sys device attribute.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_nomatch_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!sysattr)
+                return 0;
+
+        r = sd_device_enumerator_add_match_sysattr(udev_enumerate->enumerator, sysattr, value, false);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_match_property:
+ * @udev_enumerate: context
+ * @property: filter for a property of the device to include in the list
+ * @value: value of the property
+ *
+ * Match only devices with a certain property.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_match_property(struct udev_enumerate *udev_enumerate, const char *property, const char *value) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!property)
+                return 0;
+
+        r = sd_device_enumerator_add_match_property(udev_enumerate->enumerator, property, value);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_match_tag:
+ * @udev_enumerate: context
+ * @tag: filter for a tag of the device to include in the list
+ *
+ * Match only devices with a certain tag.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_match_tag(struct udev_enumerate *udev_enumerate, const char *tag) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!tag)
+                return 0;
+
+        r = sd_device_enumerator_add_match_tag(udev_enumerate->enumerator, tag);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_match_parent:
+ * @udev_enumerate: context
+ * @parent: parent device where to start searching
+ *
+ * Return the devices on the subtree of one given device. The parent
+ * itself is included in the list.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_match_parent(struct udev_enumerate *udev_enumerate, struct udev_device *parent) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!parent)
+                return 0;
+
+        r = sd_device_enumerator_add_match_parent(udev_enumerate->enumerator, udev_device_get_sd_device(parent));
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_match_is_initialized:
+ * @udev_enumerate: context
+ *
+ * Match only devices which udev has set up already. This makes
+ * sure, that the device node permissions and context are properly set
+ * and that network devices are fully renamed.
+ *
+ * Usually, devices which are found in the kernel but not already
+ * handled by udev, have still pending events. Services should subscribe
+ * to monitor events and wait for these devices to become ready, instead
+ * of using uninitialized devices.
+ *
+ * For now, this will not affect devices which do not have a device node
+ * and are not network interfaces.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_match_is_initialized(struct udev_enumerate *udev_enumerate) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        r = device_enumerator_add_match_is_initialized(udev_enumerate->enumerator, MATCH_INITIALIZED_COMPAT);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_match_sysname:
+ * @udev_enumerate: context
+ * @sysname: filter for the name of the device to include in the list
+ *
+ * Match only devices with a given /sys device name.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname) {
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!sysname)
+                return 0;
+
+        r = sd_device_enumerator_add_match_sysname(udev_enumerate->enumerator, sysname);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_add_syspath:
+ * @udev_enumerate: context
+ * @syspath: path of a device
+ *
+ * Add a device to the list of devices, to retrieve it back sorted in dependency order.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_enumerate_add_syspath(struct udev_enumerate *udev_enumerate, const char *syspath) {
+        _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+        int r;
+
+        assert_return(udev_enumerate, -EINVAL);
+
+        if (!syspath)
+                return 0;
+
+        r = sd_device_new_from_syspath(&device, syspath);
+        if (r < 0)
+                return r;
+
+        r = device_enumerator_add_device(udev_enumerate->enumerator, device);
+        if (r < 0)
+                return r;
+
+        udev_enumerate->devices_uptodate = false;
+        return 0;
+}
+
+/**
+ * udev_enumerate_scan_devices:
+ * @udev_enumerate: udev enumeration context
+ *
+ * Scan /sys for all devices which match the given filters. No matches
+ * will return all currently available devices.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ **/
+_public_ int udev_enumerate_scan_devices(struct udev_enumerate *udev_enumerate) {
+        assert_return(udev_enumerate, -EINVAL);
+
+        return device_enumerator_scan_devices(udev_enumerate->enumerator);
+}
+
+/**
+ * udev_enumerate_scan_subsystems:
+ * @udev_enumerate: udev enumeration context
+ *
+ * Scan /sys for all kernel subsystems, including buses, classes, drivers.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ **/
+_public_ int udev_enumerate_scan_subsystems(struct udev_enumerate *udev_enumerate) {
+        assert_return(udev_enumerate, -EINVAL);
+
+        return device_enumerator_scan_subsystems(udev_enumerate->enumerator);
+}
diff --git a/src/libudev/libudev-hwdb.c b/src/libudev/libudev-hwdb.c
new file mode 100644
index 0000000..8e9ea97
--- /dev/null
+++ b/src/libudev/libudev-hwdb.c
@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+
+#include "sd-hwdb.h"
+
+#include "alloc-util.h"
+#include "hwdb-util.h"
+#include "libudev-list-internal.h"
+
+/**
+ * SECTION:libudev-hwdb
+ * @short_description: retrieve properties from the hardware database
+ *
+ * Libudev hardware database interface.
+ */
+
+/**
+ * udev_hwdb:
+ *
+ * Opaque object representing the hardware database.
+ */
+struct udev_hwdb {
+        unsigned n_ref;
+        sd_hwdb *hwdb;
+        struct udev_list *properties_list;
+};
+
+/**
+ * udev_hwdb_new:
+ * @udev: udev library context (unused)
+ *
+ * Create a hardware database context to query properties for devices.
+ *
+ * Returns: a hwdb context.
+ **/
+_public_ struct udev_hwdb *udev_hwdb_new(struct udev *udev) {
+        _cleanup_(udev_list_freep) struct udev_list *list = NULL;
+        _cleanup_(sd_hwdb_unrefp) sd_hwdb *hwdb_internal = NULL;
+        struct udev_hwdb *hwdb;
+        int r;
+
+        r = sd_hwdb_new(&hwdb_internal);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        list = udev_list_new(true);
+        if (!list)
+                return_with_errno(NULL, ENOMEM);
+
+        hwdb = new(struct udev_hwdb, 1);
+        if (!hwdb)
+                return_with_errno(NULL, ENOMEM);
+
+        *hwdb = (struct udev_hwdb) {
+                .n_ref = 1,
+                .hwdb = TAKE_PTR(hwdb_internal),
+                .properties_list = TAKE_PTR(list),
+        };
+
+        return hwdb;
+}
+
+static struct udev_hwdb *udev_hwdb_free(struct udev_hwdb *hwdb) {
+        assert(hwdb);
+
+        sd_hwdb_unref(hwdb->hwdb);
+        udev_list_free(hwdb->properties_list);
+        return mfree(hwdb);
+}
+
+/**
+ * udev_hwdb_ref:
+ * @hwdb: context
+ *
+ * Take a reference of a hwdb context.
+ *
+ * Returns: the passed enumeration context
+ **/
+
+/**
+ * udev_hwdb_unref:
+ * @hwdb: context
+ *
+ * Drop a reference of a hwdb context. If the refcount reaches zero,
+ * all resources of the hwdb context will be released.
+ *
+ * Returns: #NULL
+ **/
+DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(struct udev_hwdb, udev_hwdb, udev_hwdb_free);
+
+/**
+ * udev_hwdb_get_properties_list_entry:
+ * @hwdb: context
+ * @modalias: modalias string
+ * @flags: (unused)
+ *
+ * Lookup a matching device in the hardware database. The lookup key is a
+ * modalias string, whose formats are defined for the Linux kernel modules.
+ * Examples are: pci:v00008086d00001C2D*, usb:v04F2pB221*. The first entry
+ * of a list of retrieved properties is returned.
+ *
+ * Returns: a udev_list_entry.
+ */
+_public_ struct udev_list_entry *udev_hwdb_get_properties_list_entry(struct udev_hwdb *hwdb, const char *modalias, unsigned flags) {
+        const char *key, *value;
+        struct udev_list_entry *e;
+
+        assert_return_errno(hwdb, NULL, EINVAL);
+        assert_return_errno(modalias, NULL, EINVAL);
+
+        udev_list_cleanup(hwdb->properties_list);
+
+        SD_HWDB_FOREACH_PROPERTY(hwdb->hwdb, modalias, key, value)
+                if (!udev_list_entry_add(hwdb->properties_list, key, value))
+                        return_with_errno(NULL, ENOMEM);
+
+        e = udev_list_get_entry(hwdb->properties_list);
+        if (!e)
+                return_with_errno(NULL, ENODATA);
+
+        return e;
+}
diff --git a/src/libudev/libudev-list-internal.h b/src/libudev/libudev-list-internal.h
new file mode 100644
index 0000000..c23735e
--- /dev/null
+++ b/src/libudev/libudev-list-internal.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "libudev.h"
+
+#include "macro.h"
+
+struct udev_list;
+
+struct udev_list *udev_list_new(bool unique);
+void udev_list_cleanup(struct udev_list *list);
+struct udev_list *udev_list_free(struct udev_list *list);
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev_list *, udev_list_free);
+
+struct udev_list_entry *udev_list_get_entry(struct udev_list *list);
+struct udev_list_entry *udev_list_entry_add(struct udev_list *list, const char *name, const char *value);
diff --git a/src/libudev/libudev-list.c b/src/libudev/libudev-list.c
new file mode 100644
index 0000000..0adc1d5
--- /dev/null
+++ b/src/libudev/libudev-list.c
@@ -0,0 +1,235 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "hashmap.h"
+#include "libudev-list-internal.h"
+#include "list.h"
+#include "sort-util.h"
+
+/**
+ * SECTION:libudev-list
+ * @short_description: list operation
+ *
+ * Libudev list operations.
+ */
+
+/**
+ * udev_list_entry:
+ *
+ * Opaque object representing one entry in a list. An entry contains
+ * contains a name, and optionally a value.
+ */
+struct udev_list_entry {
+        struct udev_list *list;
+        char *name;
+        char *value;
+
+        LIST_FIELDS(struct udev_list_entry, entries);
+};
+
+struct udev_list {
+        Hashmap *unique_entries;
+        LIST_HEAD(struct udev_list_entry, entries);
+        bool unique:1;
+        bool uptodate:1;
+};
+
+static struct udev_list_entry *udev_list_entry_free(struct udev_list_entry *entry) {
+        if (!entry)
+                return NULL;
+
+        if (entry->list) {
+                if (entry->list->unique && entry->name)
+                        hashmap_remove(entry->list->unique_entries, entry->name);
+
+                if (!entry->list->unique || entry->list->uptodate)
+                        LIST_REMOVE(entries, entry->list->entries, entry);
+        }
+
+        free(entry->name);
+        free(entry->value);
+
+        return mfree(entry);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev_list_entry *, udev_list_entry_free);
+
+struct udev_list *udev_list_new(bool unique) {
+        struct udev_list *list;
+
+        list = new(struct udev_list, 1);
+        if (!list)
+                return NULL;
+
+        *list = (struct udev_list) {
+                .unique = unique,
+        };
+
+        return list;
+}
+
+struct udev_list_entry *udev_list_entry_add(struct udev_list *list, const char *_name, const char *_value) {
+        _cleanup_(udev_list_entry_freep) struct udev_list_entry *entry = NULL;
+        _cleanup_free_ char *name = NULL, *value = NULL;
+
+        assert(list);
+        assert(_name);
+
+        name = strdup(_name);
+        if (!name)
+                return NULL;
+
+        if (_value) {
+                value = strdup(_value);
+                if (!value)
+                        return NULL;
+        }
+
+        entry = new(struct udev_list_entry, 1);
+        if (!entry)
+                return NULL;
+
+        *entry = (struct udev_list_entry) {
+                .name = TAKE_PTR(name),
+                .value = TAKE_PTR(value),
+        };
+
+        if (list->unique) {
+                udev_list_entry_free(hashmap_get(list->unique_entries, entry->name));
+
+                if (hashmap_ensure_put(&list->unique_entries, &string_hash_ops, entry->name, entry) < 0)
+                        return NULL;
+
+                list->uptodate = false;
+        } else
+                LIST_APPEND(entries, list->entries, entry);
+
+        entry->list = list;
+
+        return TAKE_PTR(entry);
+}
+
+void udev_list_cleanup(struct udev_list *list) {
+        if (!list)
+                return;
+
+        if (list->unique) {
+                list->uptodate = false;
+                hashmap_clear_with_destructor(list->unique_entries, udev_list_entry_free);
+        } else
+                LIST_FOREACH(entries, i, list->entries)
+                        udev_list_entry_free(i);
+}
+
+struct udev_list *udev_list_free(struct udev_list *list) {
+        if (!list)
+                return NULL;
+
+        udev_list_cleanup(list);
+        hashmap_free(list->unique_entries);
+
+        return mfree(list);
+}
+
+static int udev_list_entry_compare_func(struct udev_list_entry * const *a, struct udev_list_entry * const *b) {
+        return strcmp((*a)->name, (*b)->name);
+}
+
+struct udev_list_entry *udev_list_get_entry(struct udev_list *list) {
+        if (!list)
+                return NULL;
+
+        if (list->unique && !list->uptodate) {
+                size_t n;
+
+                LIST_HEAD_INIT(list->entries);
+
+                n = hashmap_size(list->unique_entries);
+                if (n == 0)
+                        ;
+                else if (n == 1)
+                        LIST_PREPEND(entries, list->entries, hashmap_first(list->unique_entries));
+                else {
+                        _cleanup_free_ struct udev_list_entry **buf = NULL;
+                        struct udev_list_entry *entry, **p;
+
+                        buf = new(struct udev_list_entry *, n);
+                        if (!buf)
+                                return NULL;
+
+                        p = buf;
+                        HASHMAP_FOREACH(entry, list->unique_entries)
+                                *p++ = entry;
+
+                        typesafe_qsort(buf, n, udev_list_entry_compare_func);
+
+                        for (size_t j = n; j > 0; j--)
+                                LIST_PREPEND(entries, list->entries, buf[j-1]);
+                }
+
+                list->uptodate = true;
+        }
+
+        return list->entries;
+}
+
+/**
+ * udev_list_entry_get_next:
+ * @list_entry: current entry
+ *
+ * Get the next entry from the list.
+ *
+ * Returns: udev_list_entry, #NULL if no more entries are available.
+ */
+_public_ struct udev_list_entry *udev_list_entry_get_next(struct udev_list_entry *list_entry) {
+        if (!list_entry)
+                return NULL;
+        if (list_entry->list->unique && !list_entry->list->uptodate)
+                return NULL;
+        return list_entry->entries_next;
+}
+
+/**
+ * udev_list_entry_get_by_name:
+ * @list_entry: current entry
+ * @name: name string to match
+ *
+ * Lookup an entry in the list with a certain name.
+ *
+ * Returns: udev_list_entry, #NULL if no matching entry is found.
+ */
+_public_ struct udev_list_entry *udev_list_entry_get_by_name(struct udev_list_entry *list_entry, const char *name) {
+        if (!list_entry)
+                return NULL;
+        if (!list_entry->list->unique || !list_entry->list->uptodate)
+                return NULL;
+        return hashmap_get(list_entry->list->unique_entries, name);
+}
+
+/**
+ * udev_list_entry_get_name:
+ * @list_entry: current entry
+ *
+ * Get the name of a list entry.
+ *
+ * Returns: the name string of this entry.
+ */
+_public_ const char *udev_list_entry_get_name(struct udev_list_entry *list_entry) {
+        if (!list_entry)
+                return NULL;
+        return list_entry->name;
+}
+
+/**
+ * udev_list_entry_get_value:
+ * @list_entry: current entry
+ *
+ * Get the value of list entry.
+ *
+ * Returns: the value string of this entry.
+ */
+_public_ const char *udev_list_entry_get_value(struct udev_list_entry *list_entry) {
+        if (!list_entry)
+                return NULL;
+        return list_entry->value;
+}
diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c
new file mode 100644
index 0000000..d7c931d
--- /dev/null
+++ b/src/libudev/libudev-monitor.c
@@ -0,0 +1,309 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <poll.h>
+
+#include "libudev.h"
+
+#include "alloc-util.h"
+#include "device-monitor-private.h"
+#include "device-private.h"
+#include "device-util.h"
+#include "io-util.h"
+#include "libudev-device-internal.h"
+#include "string-util.h"
+
+/**
+ * SECTION:libudev-monitor
+ * @short_description: device event source
+ *
+ * Connects to a device event source.
+ */
+
+/**
+ * udev_monitor:
+ *
+ * Opaque object handling an event source.
+ */
+struct udev_monitor {
+        struct udev *udev;
+        unsigned n_ref;
+        sd_device_monitor *monitor;
+};
+
+static MonitorNetlinkGroup monitor_netlink_group_from_string(const char *name) {
+        if (!name)
+                return MONITOR_GROUP_NONE;
+        if (streq(name, "udev"))
+                return MONITOR_GROUP_UDEV;
+        if (streq(name, "kernel"))
+                return MONITOR_GROUP_KERNEL;
+        return _MONITOR_NETLINK_GROUP_INVALID;
+}
+
+/**
+ * udev_monitor_new_from_netlink:
+ * @udev: udev library context
+ * @name: name of event source
+ *
+ * Create new udev monitor and connect to a specified event
+ * source. Valid sources identifiers are "udev" and "kernel".
+ *
+ * Applications should usually not connect directly to the
+ * "kernel" events, because the devices might not be usable
+ * at that time, before udev has configured them, and created
+ * device nodes. Accessing devices at the same time as udev,
+ * might result in unpredictable behavior. The "udev" events
+ * are sent out after udev has finished its event processing,
+ * all rules have been processed, and needed device nodes are
+ * created.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev monitor.
+ *
+ * Returns: a new udev monitor, or #NULL, in case of an error
+ **/
+_public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name) {
+        _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *m = NULL;
+        struct udev_monitor *udev_monitor;
+        MonitorNetlinkGroup g;
+        int r;
+
+        g = monitor_netlink_group_from_string(name);
+        if (g < 0)
+                return_with_errno(NULL, EINVAL);
+
+        r = device_monitor_new_full(&m, g, -1);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        udev_monitor = new(struct udev_monitor, 1);
+        if (!udev_monitor)
+                return_with_errno(NULL, ENOMEM);
+
+        *udev_monitor = (struct udev_monitor) {
+                .udev = udev,
+                .n_ref = 1,
+                .monitor = TAKE_PTR(m),
+        };
+
+        return udev_monitor;
+}
+
+/**
+ * udev_monitor_filter_update:
+ * @udev_monitor: monitor
+ *
+ * Update the installed socket filter. This is only needed,
+ * if the filter was removed or changed.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor) {
+        assert_return(udev_monitor, -EINVAL);
+
+        return sd_device_monitor_filter_update(udev_monitor->monitor);
+}
+
+/**
+ * udev_monitor_enable_receiving:
+ * @udev_monitor: the monitor which should receive events
+ *
+ * Binds the @udev_monitor socket to the event source.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor) {
+        assert_return(udev_monitor, -EINVAL);
+
+        return device_monitor_enable_receiving(udev_monitor->monitor);
+}
+
+/**
+ * udev_monitor_set_receive_buffer_size:
+ * @udev_monitor: the monitor which should receive events
+ * @size: the size in bytes
+ *
+ * Set the size of the kernel socket buffer. This call needs the
+ * appropriate privileges to succeed.
+ *
+ * Returns: 0 on success, otherwise -1 on error.
+ */
+_public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size) {
+        assert_return(udev_monitor, -EINVAL);
+
+        return sd_device_monitor_set_receive_buffer_size(udev_monitor->monitor, (size_t) size);
+}
+
+static struct udev_monitor *udev_monitor_free(struct udev_monitor *udev_monitor) {
+        assert(udev_monitor);
+
+        sd_device_monitor_unref(udev_monitor->monitor);
+        return mfree(udev_monitor);
+}
+
+/**
+ * udev_monitor_ref:
+ * @udev_monitor: udev monitor
+ *
+ * Take a reference of a udev monitor.
+ *
+ * Returns: the passed udev monitor
+ **/
+
+/**
+ * udev_monitor_unref:
+ * @udev_monitor: udev monitor
+ *
+ * Drop a reference of a udev monitor. If the refcount reaches zero,
+ * the bound socket will be closed, and the resources of the monitor
+ * will be released.
+ *
+ * Returns: #NULL
+ **/
+DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(struct udev_monitor, udev_monitor, udev_monitor_free);
+
+/**
+ * udev_monitor_get_udev:
+ * @udev_monitor: udev monitor
+ *
+ * Retrieve the udev library context the monitor was created with.
+ *
+ * Returns: the udev library context
+ **/
+_public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor) {
+        assert_return(udev_monitor, NULL);
+
+        return udev_monitor->udev;
+}
+
+/**
+ * udev_monitor_get_fd:
+ * @udev_monitor: udev monitor
+ *
+ * Retrieve the socket file descriptor associated with the monitor.
+ *
+ * Returns: the socket file descriptor
+ **/
+_public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor) {
+        assert_return(udev_monitor, -EINVAL);
+
+        return device_monitor_get_fd(udev_monitor->monitor);
+}
+
+static int udev_monitor_receive_sd_device(struct udev_monitor *udev_monitor, sd_device **ret) {
+        int r;
+
+        assert(udev_monitor);
+        assert(ret);
+
+        for (;;) {
+                /* r == 0 means a device is received but it does not pass the current filter. */
+                r = device_monitor_receive_device(udev_monitor->monitor, ret);
+                if (r != 0)
+                        return r;
+
+                for (;;) {
+                        /* Wait for next message */
+                        r = fd_wait_for_event(device_monitor_get_fd(udev_monitor->monitor), POLLIN, 0);
+                        if (r == -EINTR)
+                                continue;
+                        if (r < 0)
+                                return r;
+                        if (r == 0)
+                                return -EAGAIN;
+
+                        /* Receive next message */
+                        break;
+                }
+        }
+}
+
+/**
+ * udev_monitor_receive_device:
+ * @udev_monitor: udev monitor
+ *
+ * Receive data from the udev monitor socket, allocate a new udev
+ * device, fill in the received data, and return the device.
+ *
+ * Only socket connections with uid=0 are accepted.
+ *
+ * The monitor socket is by default set to NONBLOCK. A variant of poll() on
+ * the file descriptor returned by udev_monitor_get_fd() should to be used to
+ * wake up when new devices arrive, or alternatively the file descriptor
+ * switched into blocking mode.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev device.
+ *
+ * Returns: a new udev device, or #NULL, in case of an error
+ **/
+_public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor) {
+        _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+        int r;
+
+        assert_return(udev_monitor, NULL);
+
+        r = udev_monitor_receive_sd_device(udev_monitor, &device);
+        if (r < 0)
+                return_with_errno(NULL, r);
+
+        return udev_device_new(udev_monitor->udev, device);
+}
+
+/**
+ * udev_monitor_filter_add_match_subsystem_devtype:
+ * @udev_monitor: the monitor
+ * @subsystem: the subsystem value to match the incoming devices against
+ * @devtype: the devtype value to match the incoming devices against
+ *
+ * This filter is efficiently executed inside the kernel, and libudev subscribers
+ * will usually not be woken up for devices which do not match.
+ *
+ * The filter must be installed before the monitor is switched to listening mode.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype) {
+        int r;
+
+        assert_return(udev_monitor, -EINVAL);
+
+        r = sd_device_monitor_filter_add_match_subsystem_devtype(udev_monitor->monitor, subsystem, devtype);
+        return r < 0 ? r : 0;
+}
+
+/**
+ * udev_monitor_filter_add_match_tag:
+ * @udev_monitor: the monitor
+ * @tag: the name of a tag
+ *
+ * This filter is efficiently executed inside the kernel, and libudev subscribers
+ * will usually not be woken up for devices which do not match.
+ *
+ * The filter must be installed before the monitor is switched to listening mode.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag) {
+        int r;
+
+        assert_return(udev_monitor, -EINVAL);
+
+        r = sd_device_monitor_filter_add_match_tag(udev_monitor->monitor, tag);
+        return r < 0 ? r : 0;
+}
+
+/**
+ * udev_monitor_filter_remove:
+ * @udev_monitor: monitor
+ *
+ * Remove all filters from monitor.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+_public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor) {
+        assert_return(udev_monitor, -EINVAL);
+
+        return sd_device_monitor_filter_remove(udev_monitor->monitor);
+}
diff --git a/src/libudev/libudev-queue.c b/src/libudev/libudev-queue.c
new file mode 100644
index 0000000..0af99e5
--- /dev/null
+++ b/src/libudev/libudev-queue.c
@@ -0,0 +1,231 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+  Copyright © 2009 Alan Jenkins <alan-jenkins@tuffmail.co.uk>
+***/
+
+#include <errno.h>
+#include <unistd.h>
+
+#include "libudev.h"
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "io-util.h"
+#include "udev-util.h"
+
+/**
+ * SECTION:libudev-queue
+ * @short_description: access to currently active events
+ *
+ * This exports the current state of the udev processing queue.
+ */
+
+/**
+ * udev_queue:
+ *
+ * Opaque object representing the current event queue in the udev daemon.
+ */
+struct udev_queue {
+        struct udev *udev;
+        unsigned n_ref;
+        int fd;
+};
+
+/**
+ * udev_queue_new:
+ * @udev: udev library context
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev queue context.
+ *
+ * Returns: the udev queue context, or #NULL on error.
+ **/
+_public_ struct udev_queue *udev_queue_new(struct udev *udev) {
+        struct udev_queue *udev_queue;
+
+        udev_queue = new(struct udev_queue, 1);
+        if (!udev_queue)
+                return_with_errno(NULL, ENOMEM);
+
+        *udev_queue = (struct udev_queue) {
+                .udev = udev,
+                .n_ref = 1,
+                .fd = -EBADF,
+        };
+
+        return udev_queue;
+}
+
+static struct udev_queue *udev_queue_free(struct udev_queue *udev_queue) {
+        assert(udev_queue);
+
+        safe_close(udev_queue->fd);
+        return mfree(udev_queue);
+}
+
+/**
+ * udev_queue_ref:
+ * @udev_queue: udev queue context
+ *
+ * Take a reference of a udev queue context.
+ *
+ * Returns: the same udev queue context.
+ **/
+
+/**
+ * udev_queue_unref:
+ * @udev_queue: udev queue context
+ *
+ * Drop a reference of a udev queue context. If the refcount reaches zero,
+ * the resources of the queue context will be released.
+ *
+ * Returns: #NULL
+ **/
+DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(struct udev_queue, udev_queue, udev_queue_free);
+
+/**
+ * udev_queue_get_udev:
+ * @udev_queue: udev queue context
+ *
+ * Retrieve the udev library context the queue context was created with.
+ *
+ * Returns: the udev library context.
+ **/
+_public_ struct udev *udev_queue_get_udev(struct udev_queue *udev_queue) {
+        assert_return_errno(udev_queue, NULL, EINVAL);
+
+        return udev_queue->udev;
+}
+
+/**
+ * udev_queue_get_kernel_seqnum:
+ * @udev_queue: udev queue context
+ *
+ * This function is deprecated.
+ *
+ * Returns: 0.
+ **/
+_public_ unsigned long long int udev_queue_get_kernel_seqnum(struct udev_queue *udev_queue) {
+        return 0;
+}
+
+/**
+ * udev_queue_get_udev_seqnum:
+ * @udev_queue: udev queue context
+ *
+ * This function is deprecated.
+ *
+ * Returns: 0.
+ **/
+_public_ unsigned long long int udev_queue_get_udev_seqnum(struct udev_queue *udev_queue) {
+        return 0;
+}
+
+/**
+ * udev_queue_get_udev_is_active:
+ * @udev_queue: udev queue context
+ *
+ * Check if udev is active on the system.
+ *
+ * Returns: a flag indicating if udev is active.
+ **/
+_public_ int udev_queue_get_udev_is_active(struct udev_queue *udev_queue) {
+        return access("/run/udev/control", F_OK) >= 0;
+}
+
+/**
+ * udev_queue_get_queue_is_empty:
+ * @udev_queue: udev queue context
+ *
+ * Check if udev is currently processing any events.
+ *
+ * Returns: a flag indicating if udev is currently handling events.
+ **/
+_public_ int udev_queue_get_queue_is_empty(struct udev_queue *udev_queue) {
+        return udev_queue_is_empty() > 0;
+}
+
+/**
+ * udev_queue_get_seqnum_sequence_is_finished:
+ * @udev_queue: udev queue context
+ * @start: first event sequence number
+ * @end: last event sequence number
+ *
+ * This function is deprecated, and equivalent to udev_queue_get_queue_is_empty().
+ *
+ * Returns: a flag indicating if udev is currently handling events.
+ **/
+_public_ int udev_queue_get_seqnum_sequence_is_finished(struct udev_queue *udev_queue,
+                                                        unsigned long long int start, unsigned long long int end) {
+        return udev_queue_is_empty() > 0;
+}
+
+/**
+ * udev_queue_get_seqnum_is_finished:
+ * @udev_queue: udev queue context
+ * @seqnum: sequence number
+ *
+ * This function is deprecated, and equivalent to udev_queue_get_queue_is_empty().
+ *
+ * Returns: a flag indicating if udev is currently handling events.
+ **/
+_public_ int udev_queue_get_seqnum_is_finished(struct udev_queue *udev_queue, unsigned long long int seqnum) {
+        return udev_queue_is_empty() > 0;
+}
+
+/**
+ * udev_queue_get_queued_list_entry:
+ * @udev_queue: udev queue context
+ *
+ * This function is deprecated.
+ *
+ * Returns: NULL.
+ **/
+_public_ struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_queue *udev_queue) {
+        return_with_errno(NULL, ENODATA);
+}
+
+/**
+ * udev_queue_get_fd:
+ * @udev_queue: udev queue context
+ *
+ * Returns: a file descriptor to watch for a queue to become empty.
+ */
+_public_ int udev_queue_get_fd(struct udev_queue *udev_queue) {
+        _cleanup_close_ int fd = -EBADF;
+
+        assert_return(udev_queue, -EINVAL);
+
+        if (udev_queue->fd >= 0)
+                return udev_queue->fd;
+
+        fd = inotify_init1(IN_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        if (inotify_add_watch(fd, "/run/udev" , IN_DELETE) < 0)
+                return -errno;
+
+        return udev_queue->fd = TAKE_FD(fd);
+}
+
+/**
+ * udev_queue_flush:
+ * @udev_queue: udev queue context
+ *
+ * Returns: the result of clearing the watch for queue changes.
+ */
+_public_ int udev_queue_flush(struct udev_queue *udev_queue) {
+        int r;
+
+        assert_return(udev_queue, -EINVAL);
+
+        if (udev_queue->fd < 0)
+                return -EINVAL;
+
+        r = flush_fd(udev_queue->fd);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
diff --git a/src/libudev/libudev-util.c b/src/libudev/libudev-util.c
new file mode 100644
index 0000000..8c51877
--- /dev/null
+++ b/src/libudev/libudev-util.c
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "device-nodes.h"
+#include "libudev-util.h"
+
+/**
+ * SECTION:libudev-util
+ * @short_description: utils
+ *
+ * Utilities useful when dealing with devices and device node names.
+ */
+
+/**
+ * udev_util_encode_string:
+ * @str: input string to be encoded
+ * @str_enc: output string to store the encoded input string
+ * @len: maximum size of the output string, which may be
+ *       four times as long as the input string
+ *
+ * Encode all potentially unsafe characters of a string to the
+ * corresponding 2 char hex value prefixed by '\x'.
+ *
+ * Returns: 0 if the entire string was copied, non-zero otherwise.
+ **/
+_public_ int udev_util_encode_string(const char *str, char *str_enc, size_t len) {
+        return encode_devnode_name(str, str_enc, len);
+}
diff --git a/src/libudev/libudev-util.h b/src/libudev/libudev-util.h
new file mode 100644
index 0000000..0dc18d4
--- /dev/null
+++ b/src/libudev/libudev-util.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "libudev.h"
+
+#include "macro.h"
+
+/* Cleanup functions */
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev*, udev_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev_device*, udev_device_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev_enumerate*, udev_enumerate_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev_monitor*, udev_monitor_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev_hwdb*, udev_hwdb_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct udev_queue*, udev_queue_unref);
diff --git a/src/libudev/libudev.c b/src/libudev/libudev.c
new file mode 100644
index 0000000..7357487
--- /dev/null
+++ b/src/libudev/libudev.c
@@ -0,0 +1,154 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <ctype.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "libudev.h"
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "string-util.h"
+
+/**
+ * SECTION:libudev
+ * @short_description: libudev context
+ */
+
+/**
+ * udev:
+ *
+ * Opaque object representing the library context.
+ */
+struct udev {
+        unsigned n_ref;
+        void *userdata;
+};
+
+/**
+ * udev_get_userdata:
+ * @udev: udev library context
+ *
+ * Retrieve stored data pointer from library context. This might be useful
+ * to access from callbacks.
+ *
+ * Returns: stored userdata
+ **/
+_public_ void *udev_get_userdata(struct udev *udev) {
+        assert_return(udev, NULL);
+
+        return udev->userdata;
+}
+
+/**
+ * udev_set_userdata:
+ * @udev: udev library context
+ * @userdata: data pointer
+ *
+ * Store custom @userdata in the library context.
+ **/
+_public_ void udev_set_userdata(struct udev *udev, void *userdata) {
+        if (!udev)
+                return;
+
+        udev->userdata = userdata;
+}
+
+/**
+ * udev_new:
+ *
+ * Create udev library context. This only allocates the basic data structure.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev library context.
+ *
+ * Returns: a new udev library context
+ **/
+_public_ struct udev *udev_new(void) {
+        struct udev *udev;
+
+        udev = new(struct udev, 1);
+        if (!udev)
+                return_with_errno(NULL, ENOMEM);
+
+        *udev = (struct udev) {
+                .n_ref = 1,
+        };
+
+        return udev;
+}
+
+/**
+ * udev_ref:
+ * @udev: udev library context
+ *
+ * Take a reference of the udev library context.
+ *
+ * Returns: the passed udev library context
+ **/
+DEFINE_PUBLIC_TRIVIAL_REF_FUNC(struct udev, udev);
+
+/**
+ * udev_unref:
+ * @udev: udev library context
+ *
+ * Drop a reference of the udev library context. If the refcount
+ * reaches zero, the resources of the context will be released.
+ *
+ * Returns: the passed udev library context if it has still an active reference, or #NULL otherwise.
+ **/
+_public_ struct udev *udev_unref(struct udev *udev) {
+        if (!udev)
+                return NULL;
+
+        assert(udev->n_ref > 0);
+        udev->n_ref--;
+        if (udev->n_ref > 0)
+                /* This is different from our convention, but let's keep backward
+                 * compatibility. So, do not use DEFINE_PUBLIC_TRIVIAL_UNREF_FUNC()
+                 * macro to define this function. */
+                return udev;
+
+        return mfree(udev);
+}
+
+/**
+ * udev_set_log_fn:
+ * @udev: udev library context
+ * @log_fn: function to be called for log messages
+ *
+ * This function is deprecated.
+ *
+ **/
+_public_ void udev_set_log_fn(
+                        struct udev *udev,
+                        void (*log_fn)(struct udev *udev,
+                                       int priority, const char *file, int line, const char *fn,
+                                       const char *format, va_list args)) {
+        return;
+}
+
+/**
+ * udev_get_log_priority:
+ * @udev: udev library context
+ *
+ * This function is deprecated.
+ *
+ **/
+_public_ int udev_get_log_priority(struct udev *udev) {
+        return log_get_max_level();
+}
+
+/**
+ * udev_set_log_priority:
+ * @udev: udev library context
+ * @priority: the new log priority
+ *
+ * This function is deprecated.
+ *
+ **/
+_public_ void udev_set_log_priority(struct udev *udev, int priority) {
+        log_set_max_level(priority);
+}
diff --git a/src/libudev/libudev.h b/src/libudev/libudev.h
new file mode 100644
index 0000000..aef4a55
--- /dev/null
+++ b/src/libudev/libudev.h
@@ -0,0 +1,191 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _LIBUDEV_H_
+#define _LIBUDEV_H_
+
+#include <stdarg.h>
+#include <sys/sysmacros.h>
+#include <sys/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * udev - library context
+ *
+ * reads the udev config and system environment
+ * allows custom logging
+ */
+struct udev;
+struct udev *udev_ref(struct udev *udev);
+struct udev *udev_unref(struct udev *udev);
+struct udev *udev_new(void);
+void udev_set_log_fn(struct udev *udev,
+                            void (*log_fn)(struct udev *udev,
+                                           int priority, const char *file, int line, const char *fn,
+                                           const char *format, va_list args)) __attribute__((__deprecated__));
+int udev_get_log_priority(struct udev *udev) __attribute__((__deprecated__));
+void udev_set_log_priority(struct udev *udev, int priority) __attribute__((__deprecated__));
+void *udev_get_userdata(struct udev *udev);
+void udev_set_userdata(struct udev *udev, void *userdata);
+
+/*
+ * udev_list
+ *
+ * access to libudev generated lists
+ */
+struct udev_list_entry;
+struct udev_list_entry *udev_list_entry_get_next(struct udev_list_entry *list_entry);
+struct udev_list_entry *udev_list_entry_get_by_name(struct udev_list_entry *list_entry, const char *name);
+const char *udev_list_entry_get_name(struct udev_list_entry *list_entry);
+const char *udev_list_entry_get_value(struct udev_list_entry *list_entry);
+/**
+ * udev_list_entry_foreach:
+ * @list_entry: entry to store the current position
+ * @first_entry: first entry to start with
+ *
+ * Helper to iterate over all entries of a list.
+ */
+#define udev_list_entry_foreach(list_entry, first_entry) \
+        for (list_entry = first_entry; \
+             list_entry; \
+             list_entry = udev_list_entry_get_next(list_entry))
+
+/*
+ * udev_device
+ *
+ * access to sysfs/kernel devices
+ */
+struct udev_device;
+struct udev_device *udev_device_ref(struct udev_device *udev_device);
+struct udev_device *udev_device_unref(struct udev_device *udev_device);
+struct udev *udev_device_get_udev(struct udev_device *udev_device);
+struct udev_device *udev_device_new_from_syspath(struct udev *udev, const char *syspath);
+struct udev_device *udev_device_new_from_devnum(struct udev *udev, char type, dev_t devnum);
+struct udev_device *udev_device_new_from_subsystem_sysname(struct udev *udev, const char *subsystem, const char *sysname);
+struct udev_device *udev_device_new_from_device_id(struct udev *udev, const char *id);
+struct udev_device *udev_device_new_from_environment(struct udev *udev);
+/* udev_device_get_parent_*() does not take a reference on the returned device, it is automatically unref'd with the parent */
+struct udev_device *udev_device_get_parent(struct udev_device *udev_device);
+struct udev_device *udev_device_get_parent_with_subsystem_devtype(struct udev_device *udev_device,
+                                                                  const char *subsystem, const char *devtype);
+/* retrieve device properties */
+const char *udev_device_get_devpath(struct udev_device *udev_device);
+const char *udev_device_get_subsystem(struct udev_device *udev_device);
+const char *udev_device_get_devtype(struct udev_device *udev_device);
+const char *udev_device_get_syspath(struct udev_device *udev_device);
+const char *udev_device_get_sysname(struct udev_device *udev_device);
+const char *udev_device_get_sysnum(struct udev_device *udev_device);
+const char *udev_device_get_devnode(struct udev_device *udev_device);
+int udev_device_get_is_initialized(struct udev_device *udev_device);
+struct udev_list_entry *udev_device_get_devlinks_list_entry(struct udev_device *udev_device);
+struct udev_list_entry *udev_device_get_properties_list_entry(struct udev_device *udev_device);
+struct udev_list_entry *udev_device_get_tags_list_entry(struct udev_device *udev_device);
+struct udev_list_entry *udev_device_get_current_tags_list_entry(struct udev_device *udev_device);
+struct udev_list_entry *udev_device_get_sysattr_list_entry(struct udev_device *udev_device);
+const char *udev_device_get_property_value(struct udev_device *udev_device, const char *key);
+const char *udev_device_get_driver(struct udev_device *udev_device);
+dev_t udev_device_get_devnum(struct udev_device *udev_device);
+const char *udev_device_get_action(struct udev_device *udev_device);
+unsigned long long int udev_device_get_seqnum(struct udev_device *udev_device);
+unsigned long long int udev_device_get_usec_since_initialized(struct udev_device *udev_device);
+const char *udev_device_get_sysattr_value(struct udev_device *udev_device, const char *sysattr);
+int udev_device_set_sysattr_value(struct udev_device *udev_device, const char *sysattr, const char *value);
+int udev_device_has_tag(struct udev_device *udev_device, const char *tag);
+int udev_device_has_current_tag(struct udev_device *udev_device, const char *tag);
+
+/*
+ * udev_monitor
+ *
+ * access to kernel uevents and udev events
+ */
+struct udev_monitor;
+struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor);
+struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor);
+struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor);
+/* kernel and udev generated events over netlink */
+struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name);
+/* bind socket */
+int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor);
+int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size);
+int udev_monitor_get_fd(struct udev_monitor *udev_monitor);
+struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor);
+/* in-kernel socket filters to select messages that get delivered to a listener */
+int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor,
+                                                    const char *subsystem, const char *devtype);
+int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag);
+int udev_monitor_filter_update(struct udev_monitor *udev_monitor);
+int udev_monitor_filter_remove(struct udev_monitor *udev_monitor);
+
+/*
+ * udev_enumerate
+ *
+ * search sysfs for specific devices and provide a sorted list
+ */
+struct udev_enumerate;
+struct udev_enumerate *udev_enumerate_ref(struct udev_enumerate *udev_enumerate);
+struct udev_enumerate *udev_enumerate_unref(struct udev_enumerate *udev_enumerate);
+struct udev *udev_enumerate_get_udev(struct udev_enumerate *udev_enumerate);
+struct udev_enumerate *udev_enumerate_new(struct udev *udev);
+/* device properties filter */
+int udev_enumerate_add_match_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem);
+int udev_enumerate_add_nomatch_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem);
+int udev_enumerate_add_match_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value);
+int udev_enumerate_add_nomatch_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value);
+int udev_enumerate_add_match_property(struct udev_enumerate *udev_enumerate, const char *property, const char *value);
+int udev_enumerate_add_match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname);
+int udev_enumerate_add_match_tag(struct udev_enumerate *udev_enumerate, const char *tag);
+int udev_enumerate_add_match_parent(struct udev_enumerate *udev_enumerate, struct udev_device *parent);
+int udev_enumerate_add_match_is_initialized(struct udev_enumerate *udev_enumerate);
+int udev_enumerate_add_syspath(struct udev_enumerate *udev_enumerate, const char *syspath);
+/* run enumeration with active filters */
+int udev_enumerate_scan_devices(struct udev_enumerate *udev_enumerate);
+int udev_enumerate_scan_subsystems(struct udev_enumerate *udev_enumerate);
+/* return device list */
+struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *udev_enumerate);
+
+/*
+ * udev_queue
+ *
+ * access to the currently running udev events
+ */
+struct udev_queue;
+struct udev_queue *udev_queue_ref(struct udev_queue *udev_queue);
+struct udev_queue *udev_queue_unref(struct udev_queue *udev_queue);
+struct udev *udev_queue_get_udev(struct udev_queue *udev_queue);
+struct udev_queue *udev_queue_new(struct udev *udev);
+unsigned long long int udev_queue_get_kernel_seqnum(struct udev_queue *udev_queue) __attribute__((__deprecated__));
+unsigned long long int udev_queue_get_udev_seqnum(struct udev_queue *udev_queue) __attribute__((__deprecated__));
+int udev_queue_get_udev_is_active(struct udev_queue *udev_queue);
+int udev_queue_get_queue_is_empty(struct udev_queue *udev_queue);
+int udev_queue_get_seqnum_is_finished(struct udev_queue *udev_queue, unsigned long long int seqnum) __attribute__((__deprecated__));
+int udev_queue_get_seqnum_sequence_is_finished(struct udev_queue *udev_queue,
+                                               unsigned long long int start, unsigned long long int end) __attribute__((__deprecated__));
+int udev_queue_get_fd(struct udev_queue *udev_queue);
+int udev_queue_flush(struct udev_queue *udev_queue);
+struct udev_list_entry *udev_queue_get_queued_list_entry(struct udev_queue *udev_queue) __attribute__((__deprecated__));
+
+/*
+ *  udev_hwdb
+ *
+ *  access to the static hardware properties database
+ */
+struct udev_hwdb;
+struct udev_hwdb *udev_hwdb_new(struct udev *udev);
+struct udev_hwdb *udev_hwdb_ref(struct udev_hwdb *hwdb);
+struct udev_hwdb *udev_hwdb_unref(struct udev_hwdb *hwdb);
+struct udev_list_entry *udev_hwdb_get_properties_list_entry(struct udev_hwdb *hwdb, const char *modalias, unsigned flags);
+
+/*
+ * udev_util
+ *
+ * udev specific utilities
+ */
+int udev_util_encode_string(const char *str, char *str_enc, size_t len);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif
diff --git a/src/libudev/libudev.pc.in b/src/libudev/libudev.pc.in
new file mode 100644
index 0000000..6541bcb
--- /dev/null
+++ b/src/libudev/libudev.pc.in
@@ -0,0 +1,20 @@
+#  SPDX-License-Identifier: LGPL-2.1-or-later
+#
+#  This file is part of systemd.
+#
+#  systemd 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 2.1 of the License, or
+#  (at your option) any later version.
+
+prefix={{PREFIX}}
+exec_prefix={{PREFIX}}
+libdir={{LIBDIR}}
+includedir={{INCLUDE_DIR}}
+
+Name: libudev
+Description: Library to access udev device information
+Version: {{PROJECT_VERSION}}
+Libs: -L${libdir} -ludev
+Libs.private: -lrt -pthread
+Cflags: -I${includedir}
diff --git a/src/libudev/libudev.sym b/src/libudev/libudev.sym
new file mode 100644
index 0000000..6aa6768
--- /dev/null
+++ b/src/libudev/libudev.sym
@@ -0,0 +1,126 @@
+/***
+  SPDX-License-Identifier: LGPL-2.1-or-later
+
+  systemd 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 2.1 of the License, or
+  (at your option) any later version.
+***/
+
+LIBUDEV_183 {
+global:
+        udev_device_get_action;
+        udev_device_get_devlinks_list_entry;
+        udev_device_get_devnode;
+        udev_device_get_devnum;
+        udev_device_get_devpath;
+        udev_device_get_devtype;
+        udev_device_get_driver;
+        udev_device_get_is_initialized;
+        udev_device_get_parent;
+        udev_device_get_parent_with_subsystem_devtype;
+        udev_device_get_properties_list_entry;
+        udev_device_get_property_value;
+        udev_device_get_seqnum;
+        udev_device_get_subsystem;
+        udev_device_get_sysattr_list_entry;
+        udev_device_get_sysattr_value;
+        udev_device_get_sysname;
+        udev_device_get_sysnum;
+        udev_device_get_syspath;
+        udev_device_get_tags_list_entry;
+        udev_device_get_udev;
+        udev_device_get_usec_since_initialized;
+        udev_device_has_tag;
+        udev_device_new_from_devnum;
+        udev_device_new_from_environment;
+        udev_device_new_from_subsystem_sysname;
+        udev_device_new_from_syspath;
+        udev_device_ref;
+        udev_device_unref;
+        udev_enumerate_add_match_is_initialized;
+        udev_enumerate_add_match_parent;
+        udev_enumerate_add_match_property;
+        udev_enumerate_add_match_subsystem;
+        udev_enumerate_add_match_sysattr;
+        udev_enumerate_add_match_sysname;
+        udev_enumerate_add_match_tag;
+        udev_enumerate_add_nomatch_subsystem;
+        udev_enumerate_add_nomatch_sysattr;
+        udev_enumerate_add_syspath;
+        udev_enumerate_get_list_entry;
+        udev_enumerate_get_udev;
+        udev_enumerate_new;
+        udev_enumerate_ref;
+        udev_enumerate_scan_devices;
+        udev_enumerate_scan_subsystems;
+        udev_enumerate_unref;
+        udev_get_log_priority;
+        udev_get_userdata;
+        udev_list_entry_get_by_name;
+        udev_list_entry_get_name;
+        udev_list_entry_get_next;
+        udev_list_entry_get_value;
+        udev_monitor_enable_receiving;
+        udev_monitor_filter_add_match_subsystem_devtype;
+        udev_monitor_filter_add_match_tag;
+        udev_monitor_filter_remove;
+        udev_monitor_filter_update;
+        udev_monitor_get_fd;
+        udev_monitor_get_udev;
+        udev_monitor_new_from_netlink;
+        udev_monitor_receive_device;
+        udev_monitor_ref;
+        udev_monitor_set_receive_buffer_size;
+        udev_monitor_unref;
+        udev_new;
+        udev_queue_get_kernel_seqnum;
+        udev_queue_get_queue_is_empty;
+        udev_queue_get_queued_list_entry;
+        udev_queue_get_seqnum_is_finished;
+        udev_queue_get_seqnum_sequence_is_finished;
+        udev_queue_get_udev;
+        udev_queue_get_udev_is_active;
+        udev_queue_get_udev_seqnum;
+        udev_queue_new;
+        udev_queue_ref;
+        udev_queue_unref;
+        udev_ref;
+        udev_set_log_fn;
+        udev_set_log_priority;
+        udev_set_userdata;
+        udev_unref;
+        udev_util_encode_string;
+local:
+        *;
+};
+
+LIBUDEV_189 {
+global:
+        udev_device_new_from_device_id;
+} LIBUDEV_183;
+
+LIBUDEV_196 {
+global:
+        udev_hwdb_new;
+        udev_hwdb_ref;
+        udev_hwdb_unref;
+        udev_hwdb_get_properties_list_entry;
+} LIBUDEV_189;
+
+LIBUDEV_199 {
+global:
+        udev_device_set_sysattr_value;
+} LIBUDEV_196;
+
+LIBUDEV_215 {
+global:
+        udev_queue_flush;
+        udev_queue_get_fd;
+} LIBUDEV_199;
+
+LIBUDEV_247 {
+global:
+        udev_device_has_current_tag;
+        udev_device_get_current_tags_list_entry;
+} LIBUDEV_215;
diff --git a/src/libudev/meson.build b/src/libudev/meson.build
new file mode 100644
index 0000000..7f99919
--- /dev/null
+++ b/src/libudev/meson.build
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+libudev_sources = files(
+        'libudev-device.c',
+        'libudev-enumerate.c',
+        'libudev-hwdb.c',
+        'libudev-list.c',
+        'libudev-monitor.c',
+        'libudev-queue.c',
+        'libudev-util.c',
+        'libudev.c',
+)
+
+############################################################
+
+libudev_includes = [includes, include_directories('.')]
+
+libudev_dir_path = meson.current_source_dir()
+
+libudev_sym = files('libudev.sym')
+libudev_sym_path = libudev_dir_path / 'libudev.sym'
+
+install_headers('libudev.h')
+libudev_h_path = libudev_dir_path / 'libudev.h'
+
+libudev_basic = static_library(
+        'udev-basic',
+        libudev_sources,
+        include_directories : includes,
+        dependencies : userspace,
+        c_args : ['-fvisibility=default'],
+        build_by_default : false)
+
+static_libudev = get_option('static-libudev')
+static_libudev_pic = static_libudev == 'true' or static_libudev == 'pic'
+
+libudev_pc = custom_target(
+        'libudev.pc',
+        input : 'libudev.pc.in',
+        output : 'libudev.pc',
+        command : [jinja2_cmdline, '@INPUT@', '@OUTPUT@'],
+        install : pkgconfiglibdir != 'no',
+        install_tag : 'devel',
+        install_dir : pkgconfiglibdir)
diff --git a/src/libudev/test-libudev.c b/src/libudev/test-libudev.c
new file mode 100644
index 0000000..e05a062
--- /dev/null
+++ b/src/libudev/test-libudev.c
@@ -0,0 +1,496 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <getopt.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "devnum-util.h"
+#include "fd-util.h"
+#include "libudev-list-internal.h"
+#include "libudev-util.h"
+#include "log.h"
+#include "main-func.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "tests.h"
+#include "version.h"
+
+static bool arg_monitor = false;
+
+static void print_device(struct udev_device *device) {
+        const char *str;
+        dev_t devnum;
+        int count;
+        struct udev_list_entry *list_entry;
+
+        log_info("*** device: %p ***", device);
+        str = udev_device_get_action(device);
+        if (str)
+                log_info("action:    '%s'", str);
+
+        str = udev_device_get_syspath(device);
+        log_info("syspath:   '%s'", str);
+
+        str = udev_device_get_sysname(device);
+        log_info("sysname:   '%s'", str);
+
+        str = udev_device_get_sysnum(device);
+        if (str)
+                log_info("sysnum:    '%s'", str);
+
+        str = udev_device_get_devpath(device);
+        log_info("devpath:   '%s'", str);
+
+        str = udev_device_get_subsystem(device);
+        if (str)
+                log_info("subsystem: '%s'", str);
+
+        str = udev_device_get_devtype(device);
+        if (str)
+                log_info("devtype:   '%s'", str);
+
+        str = udev_device_get_driver(device);
+        if (str)
+                log_info("driver:    '%s'", str);
+
+        str = udev_device_get_devnode(device);
+        if (str)
+                log_info("devname:   '%s'", str);
+
+        devnum = udev_device_get_devnum(device);
+        if (major(devnum) > 0)
+                log_info("devnum:    %u:%u", major(devnum), minor(devnum));
+
+        count = 0;
+        udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(device)) {
+                log_info("link:      '%s'", udev_list_entry_get_name(list_entry));
+                count++;
+        }
+        if (count > 0)
+                log_info("found %i links", count);
+
+        count = 0;
+        udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(device)) {
+                log_info("property:  '%s=%s'",
+                       udev_list_entry_get_name(list_entry),
+                       udev_list_entry_get_value(list_entry));
+                count++;
+        }
+        if (count > 0)
+                log_info("found %i properties", count);
+
+        str = udev_device_get_property_value(device, "MAJOR");
+        if (str)
+                log_info("MAJOR: '%s'", str);
+
+        str = udev_device_get_sysattr_value(device, "dev");
+        if (str)
+                log_info("attr{dev}: '%s'", str);
+}
+
+static void test_device(struct udev *udev, const char *syspath) {
+        _cleanup_(udev_device_unrefp) struct udev_device *device = NULL;
+
+        log_info("/* %s, device %s */", __func__, syspath);
+        device = udev_device_new_from_syspath(udev, syspath);
+        if (device)
+                print_device(device);
+        else
+                log_warning_errno(errno, "udev_device_new_from_syspath: %m");
+}
+
+static void test_device_parents(struct udev *udev, const char *syspath) {
+        _cleanup_(udev_device_unrefp) struct udev_device *device = NULL;
+        struct udev_device *device_parent;
+
+        log_info("/* %s, device %s */", __func__, syspath);
+        device = udev_device_new_from_syspath(udev, syspath);
+        if (!device)
+                return;
+
+        log_info("looking at parents");
+        device_parent = device;
+        do {
+                print_device(device_parent);
+                device_parent = udev_device_get_parent(device_parent);
+        } while (device_parent != NULL);
+
+        log_info("looking at parents again");
+        device_parent = device;
+        do {
+                print_device(device_parent);
+                device_parent = udev_device_get_parent(device_parent);
+        } while (device_parent != NULL);
+}
+
+static void test_device_devnum(struct udev *udev) {
+        dev_t devnum = makedev(1, 3);
+        _cleanup_(udev_device_unrefp) struct udev_device *device;
+
+        log_info("/* %s, device " DEVNUM_FORMAT_STR " */", __func__, DEVNUM_FORMAT_VAL(devnum));
+
+        device = udev_device_new_from_devnum(udev, 'c', devnum);
+        if (device)
+                print_device(device);
+        else
+                log_warning_errno(errno, "udev_device_new_from_devnum: %m");
+}
+
+static void test_device_subsys_name(struct udev *udev, const char *subsys, const char *dev) {
+        _cleanup_(udev_device_unrefp) struct udev_device *device;
+
+        log_info("looking up device: '%s:%s'", subsys, dev);
+        device = udev_device_new_from_subsystem_sysname(udev, subsys, dev);
+        if (!device)
+                log_warning_errno(errno, "udev_device_new_from_subsystem_sysname: %m");
+        else
+                print_device(device);
+}
+
+static int enumerate_print_list(struct udev_enumerate *enumerate) {
+        struct udev_list_entry *list_entry;
+        int count = 0;
+
+        udev_list_entry_foreach(list_entry, udev_enumerate_get_list_entry(enumerate)) {
+                struct udev_device *device;
+
+                device = udev_device_new_from_syspath(udev_enumerate_get_udev(enumerate),
+                                                      udev_list_entry_get_name(list_entry));
+                if (device) {
+                        log_info("device: '%s' (%s)",
+                                 udev_device_get_syspath(device),
+                                 udev_device_get_subsystem(device));
+                        udev_device_unref(device);
+                        count++;
+                }
+        }
+        log_info("found %i devices", count);
+        return count;
+}
+
+static void test_monitor(struct udev *udev) {
+        _cleanup_(udev_monitor_unrefp) struct udev_monitor *udev_monitor = NULL;
+        _cleanup_close_ int fd_ep = -EBADF;
+        int fd_udev;
+        struct epoll_event ep_udev = {
+                .events = EPOLLIN,
+        }, ep_stdin = {
+                .events = EPOLLIN,
+                .data.fd = STDIN_FILENO,
+        };
+
+        log_info("/* %s */", __func__);
+
+        fd_ep = epoll_create1(EPOLL_CLOEXEC);
+        assert_se(fd_ep >= 0);
+
+        udev_monitor = udev_monitor_new_from_netlink(udev, "udev");
+        assert_se(udev_monitor != NULL);
+
+        fd_udev = udev_monitor_get_fd(udev_monitor);
+        ep_udev.data.fd = fd_udev;
+
+        assert_se(udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "block", NULL) >= 0);
+        assert_se(udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "tty", NULL) >= 0);
+        assert_se(udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "usb", "usb_device") >= 0);
+
+        assert_se(udev_monitor_enable_receiving(udev_monitor) >= 0);
+
+        assert_se(epoll_ctl(fd_ep, EPOLL_CTL_ADD, fd_udev, &ep_udev) >= 0);
+        assert_se(epoll_ctl(fd_ep, EPOLL_CTL_ADD, STDIN_FILENO, &ep_stdin) >= 0);
+
+        for (;;) {
+                int fdcount;
+                struct epoll_event ev[4];
+                struct udev_device *device;
+                int i;
+
+                printf("waiting for events from udev, press ENTER to exit\n");
+                fdcount = epoll_wait(fd_ep, ev, ELEMENTSOF(ev), -1);
+                printf("epoll fd count: %i\n", fdcount);
+
+                for (i = 0; i < fdcount; i++) {
+                        if (ev[i].data.fd == fd_udev && ev[i].events & EPOLLIN) {
+                                device = udev_monitor_receive_device(udev_monitor);
+                                if (!device) {
+                                        printf("no device from socket\n");
+                                        continue;
+                                }
+                                print_device(device);
+                                udev_device_unref(device);
+                        } else if (ev[i].data.fd == STDIN_FILENO && ev[i].events & EPOLLIN) {
+                                printf("exiting loop\n");
+                                return;
+                        }
+                }
+        }
+}
+
+static void test_queue(struct udev *udev) {
+        struct udev_queue *udev_queue;
+        bool empty;
+
+        log_info("/* %s */", __func__);
+
+        assert_se(udev_queue = udev_queue_new(udev));
+
+        empty = udev_queue_get_queue_is_empty(udev_queue);
+        log_info("queue is %s", empty ? "empty" : "not empty");
+        udev_queue_unref(udev_queue);
+}
+
+static int test_enumerate(struct udev *udev, const char *subsystem) {
+        struct udev_enumerate *udev_enumerate;
+        int r;
+
+        log_info("/* %s */", __func__);
+
+        log_info("enumerate '%s'", subsystem == NULL ? "<all>" : subsystem);
+        udev_enumerate = udev_enumerate_new(udev);
+        if (!udev_enumerate)
+                return -1;
+        udev_enumerate_add_match_subsystem(udev_enumerate, subsystem);
+        udev_enumerate_scan_devices(udev_enumerate);
+        enumerate_print_list(udev_enumerate);
+        udev_enumerate_unref(udev_enumerate);
+
+        log_info("enumerate 'net' + duplicated scan + null + zero");
+        udev_enumerate = udev_enumerate_new(udev);
+        if (!udev_enumerate)
+                return -1;
+        udev_enumerate_add_match_subsystem(udev_enumerate, "net");
+        udev_enumerate_scan_devices(udev_enumerate);
+        udev_enumerate_scan_devices(udev_enumerate);
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/zero");
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/null");
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/zero");
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/null");
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/zero");
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/null");
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/null");
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/zero");
+        udev_enumerate_add_syspath(udev_enumerate, "/sys/class/mem/zero");
+        udev_enumerate_scan_devices(udev_enumerate);
+        enumerate_print_list(udev_enumerate);
+        udev_enumerate_unref(udev_enumerate);
+
+        log_info("enumerate 'block'");
+        udev_enumerate = udev_enumerate_new(udev);
+        if (!udev_enumerate)
+                return -1;
+        udev_enumerate_add_match_subsystem(udev_enumerate,"block");
+        r = udev_enumerate_add_match_is_initialized(udev_enumerate);
+        if (r < 0) {
+                udev_enumerate_unref(udev_enumerate);
+                return r;
+        }
+        udev_enumerate_scan_devices(udev_enumerate);
+        enumerate_print_list(udev_enumerate);
+        udev_enumerate_unref(udev_enumerate);
+
+        log_info("enumerate 'not block'");
+        udev_enumerate = udev_enumerate_new(udev);
+        if (!udev_enumerate)
+                return -1;
+        udev_enumerate_add_nomatch_subsystem(udev_enumerate, "block");
+        udev_enumerate_scan_devices(udev_enumerate);
+        enumerate_print_list(udev_enumerate);
+        udev_enumerate_unref(udev_enumerate);
+
+        log_info("enumerate 'pci, mem, vc'");
+        udev_enumerate = udev_enumerate_new(udev);
+        if (!udev_enumerate)
+                return -1;
+        udev_enumerate_add_match_subsystem(udev_enumerate, "pci");
+        udev_enumerate_add_match_subsystem(udev_enumerate, "mem");
+        udev_enumerate_add_match_subsystem(udev_enumerate, "vc");
+        udev_enumerate_scan_devices(udev_enumerate);
+        enumerate_print_list(udev_enumerate);
+        udev_enumerate_unref(udev_enumerate);
+
+        log_info("enumerate 'subsystem'");
+        udev_enumerate = udev_enumerate_new(udev);
+        if (!udev_enumerate)
+                return -1;
+        udev_enumerate_scan_subsystems(udev_enumerate);
+        enumerate_print_list(udev_enumerate);
+        udev_enumerate_unref(udev_enumerate);
+
+        log_info("enumerate 'property IF_FS_*=filesystem'");
+        udev_enumerate = udev_enumerate_new(udev);
+        if (!udev_enumerate)
+                return -1;
+        udev_enumerate_add_match_property(udev_enumerate, "ID_FS*", "filesystem");
+        udev_enumerate_scan_devices(udev_enumerate);
+        enumerate_print_list(udev_enumerate);
+        udev_enumerate_unref(udev_enumerate);
+        return 0;
+}
+
+static void test_hwdb(struct udev *udev, const char *modalias) {
+        struct udev_hwdb *hwdb;
+        struct udev_list_entry *entry;
+
+        log_info("/* %s */", __func__);
+
+        hwdb = udev_hwdb_new(udev);
+        if (!hwdb)
+                log_warning_errno(errno, "Failed to open hwdb: %m");
+
+        udev_list_entry_foreach(entry, udev_hwdb_get_properties_list_entry(hwdb, modalias, 0))
+                log_info("'%s'='%s'", udev_list_entry_get_name(entry), udev_list_entry_get_value(entry));
+
+        hwdb = udev_hwdb_unref(hwdb);
+        assert_se(hwdb == NULL);
+}
+
+static void test_list(void) {
+        _cleanup_(udev_list_freep) struct udev_list *list = NULL;
+        struct udev_list_entry *e;
+
+        /* empty list */
+        assert_se(list = udev_list_new(false));
+        assert_se(!udev_list_get_entry(list));
+        list = udev_list_free(list);
+
+        /* unique == false */
+        assert_se(list = udev_list_new(false));
+        assert_se(udev_list_entry_add(list, "aaa", "hoge"));
+        assert_se(udev_list_entry_add(list, "aaa", "hogehoge"));
+        assert_se(udev_list_entry_add(list, "bbb", "foo"));
+        e = udev_list_get_entry(list);
+        assert_se(e);
+        assert_se(streq_ptr(udev_list_entry_get_name(e), "aaa"));
+        assert_se(streq_ptr(udev_list_entry_get_value(e), "hoge"));
+        e = udev_list_entry_get_next(e);
+        assert_se(e);
+        assert_se(streq_ptr(udev_list_entry_get_name(e), "aaa"));
+        assert_se(streq_ptr(udev_list_entry_get_value(e), "hogehoge"));
+        e = udev_list_entry_get_next(e);
+        assert_se(e);
+        assert_se(streq_ptr(udev_list_entry_get_name(e), "bbb"));
+        assert_se(streq_ptr(udev_list_entry_get_value(e), "foo"));
+        assert_se(!udev_list_entry_get_next(e));
+
+        assert_se(!udev_list_entry_get_by_name(e, "aaa"));
+        assert_se(!udev_list_entry_get_by_name(e, "bbb"));
+        assert_se(!udev_list_entry_get_by_name(e, "ccc"));
+        list = udev_list_free(list);
+
+        /* unique == true */
+        assert_se(list = udev_list_new(true));
+        assert_se(udev_list_entry_add(list, "aaa", "hoge"));
+        assert_se(udev_list_entry_add(list, "aaa", "hogehoge"));
+        assert_se(udev_list_entry_add(list, "bbb", "foo"));
+        e = udev_list_get_entry(list);
+        assert_se(e);
+        assert_se(streq_ptr(udev_list_entry_get_name(e), "aaa"));
+        assert_se(streq_ptr(udev_list_entry_get_value(e), "hogehoge"));
+        e = udev_list_entry_get_next(e);
+        assert_se(streq_ptr(udev_list_entry_get_name(e), "bbb"));
+        assert_se(streq_ptr(udev_list_entry_get_value(e), "foo"));
+        assert_se(!udev_list_entry_get_next(e));
+
+        e = udev_list_entry_get_by_name(e, "bbb");
+        assert_se(e);
+        assert_se(streq_ptr(udev_list_entry_get_name(e), "bbb"));
+        assert_se(streq_ptr(udev_list_entry_get_value(e), "foo"));
+        e = udev_list_entry_get_by_name(e, "aaa");
+        assert_se(e);
+        assert_se(streq_ptr(udev_list_entry_get_name(e), "aaa"));
+        assert_se(streq_ptr(udev_list_entry_get_value(e), "hogehoge"));
+        assert_se(!udev_list_entry_get_by_name(e, "ccc"));
+}
+
+static int parse_args(int argc, char *argv[], const char **syspath, const char **subsystem) {
+        static const struct option options[] = {
+                { "syspath",   required_argument, NULL, 'p' },
+                { "subsystem", required_argument, NULL, 's' },
+                { "debug",     no_argument,       NULL, 'd' },
+                { "help",      no_argument,       NULL, 'h' },
+                { "version",   no_argument,       NULL, 'V' },
+                { "monitor",   no_argument,       NULL, 'm' },
+                {}
+        };
+        int c;
+
+        while ((c = getopt_long(argc, argv, "p:s:dhVm", options, NULL)) >= 0)
+                switch (c) {
+                case 'p':
+                        *syspath = optarg;
+                        break;
+
+                case 's':
+                        *subsystem = optarg;
+                        break;
+
+                case 'd':
+                        log_set_max_level(LOG_DEBUG);
+                        break;
+
+                case 'h':
+                        printf("--debug --syspath= --subsystem= --help\n");
+                        return 0;
+
+                case 'V':
+                        printf("%s\n", GIT_VERSION);
+                        return 0;
+
+                case 'm':
+                        arg_monitor = true;
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached();
+                }
+
+        return 1;
+}
+
+static int run(int argc, char *argv[]) {
+        _cleanup_(udev_unrefp) struct udev *udev = NULL;
+
+        const char *syspath = "/devices/virtual/mem/null";
+        const char *subsystem = NULL;
+        int r;
+
+        test_setup_logging(LOG_INFO);
+
+        r = parse_args(argc, argv, &syspath, &subsystem);
+        if (r <= 0)
+                return r;
+
+        assert_se(udev = udev_new());
+
+        /* add sys path if needed */
+        if (!startswith(syspath, "/sys"))
+                syspath = strjoina("/sys/", syspath);
+
+        test_device(udev, syspath);
+        test_device_devnum(udev);
+        test_device_subsys_name(udev, "block", "sda");
+        test_device_subsys_name(udev, "subsystem", "pci");
+        test_device_subsys_name(udev, "drivers", "scsi:sd");
+        test_device_subsys_name(udev, "module", "printk");
+        test_device_parents(udev, syspath);
+
+        test_enumerate(udev, subsystem);
+
+        test_queue(udev);
+
+        test_hwdb(udev, "usb:v0D50p0011*");
+
+        if (arg_monitor)
+                test_monitor(udev);
+
+        test_list();
+
+        return 0;
+}
+
+DEFINE_MAIN_FUNCTION(run);
diff --git a/src/libudev/test-udev-device-thread.c b/src/libudev/test-udev-device-thread.c
new file mode 100644
index 0000000..c082fdc
--- /dev/null
+++ b/src/libudev/test-udev-device-thread.c
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "libudev.h"
+
+#define handle_error_errno(error, msg)                          \
+        ({                                                      \
+                errno = abs(error);                             \
+                perror(msg);                                    \
+                EXIT_FAILURE;                                   \
+        })
+
+static void* thread(void *p) {
+        struct udev_device **d = p;
+
+        *d = udev_device_unref(*d);
+
+        return NULL;
+}
+
+int main(int argc, char *argv[]) {
+        struct udev_device *loopback;
+        struct udev_list_entry *entry, *e;
+        pthread_t t;
+        int r;
+
+        loopback = udev_device_new_from_syspath(NULL, "/sys/class/net/lo");
+        if (!loopback)
+                return handle_error_errno(errno, "Failed to create loopback device object");
+
+        entry = udev_device_get_properties_list_entry(loopback);
+        udev_list_entry_foreach(e, entry)
+                printf("%s=%s\n", udev_list_entry_get_name(e), udev_list_entry_get_value(e));
+
+        r = pthread_create(&t, NULL, thread, &loopback);
+        if (r != 0)
+                return handle_error_errno(r, "Failed to create thread");
+
+        r = pthread_join(t, NULL);
+        if (r != 0)
+                return handle_error_errno(r, "Failed to wait thread finished");
+
+        if (loopback)
+                return handle_error_errno(r, "loopback device is not unref()ed");
+
+        return 0;
+}