libsystemd: add sd-device library

This provides equivalent functionality to libudev-device, but in the
systemd style. The public API only caters to creating sd_device objects
from for devices that already exist in /sys, there is no support for
listening for monitoring events or creating devices received over
the udev netlink protocol.

The private API contains the necessary functionality to make sd-device
a drop-in replacement for libudev-device, but which we would not
otherwise want to export.

7 files changed, 3234 insertions, 1 deletions

diff --git a/Makefile.am b/Makefile.am
index 93fdbc2f1e..9509247ec1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -231,6 +231,7 @@ AM_CPPFLAGS = \
 	-I $(top_srcdir)/src/libsystemd/sd-rtnl \
 	-I $(top_srcdir)/src/libsystemd/sd-network \
 	-I $(top_srcdir)/src/libsystemd/sd-hwdb \
+	-I $(top_srcdir)/src/libsystemd/sd-device \
 	-I $(top_srcdir)/src/libsystemd-network \
 	-I $(top_srcdir)/src/libsystemd-terminal \
 	$(OUR_CPPFLAGS)
@@ -2918,6 +2919,7 @@ libsystemd_internal_la_SOURCES = \
 	src/systemd/sd-path.h \
 	src/systemd/sd-network.h \
 	src/systemd/sd-hwdb.h \
+	src/systemd/sd-device.h \
 	src/libsystemd/sd-bus/sd-bus.c \
 	src/libsystemd/sd-bus/bus-control.c \
 	src/libsystemd/sd-bus/bus-control.h \
@@ -2981,7 +2983,12 @@ libsystemd_internal_la_SOURCES = \
 	src/libsystemd/sd-network/network-util.c \
 	src/libsystemd/sd-hwdb/sd-hwdb.c \
 	src/libsystemd/sd-hwdb/hwdb-util.h \
-	src/libsystemd/sd-hwdb/hwdb-internal.h
+	src/libsystemd/sd-hwdb/hwdb-intenal.h \
+	src/libsystemd/sd-device/device-internal.h \
+	src/libsystemd/sd-device/device-util.h \
+	src/libsystemd/sd-device/sd-device.c \
+	src/libsystemd/sd-device/device-private.c \
+	src/libsystemd/sd-device/device-private.h
 
 nodist_libsystemd_internal_la_SOURCES = \
 	src/libsystemd/libsystemd.sym
diff --git a/src/libsystemd/sd-device/device-internal.h b/src/libsystemd/sd-device/device-internal.h
new file mode 100644
index 0000000000..59ec1a6d73
--- /dev/null
+++ b/src/libsystemd/sd-device/device-internal.h
@@ -0,0 +1,125 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
+  Copyright 2014 Tom Gundersen <teg@jklm.no>
+
+  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.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#pragma once
+
+#include "hashmap.h"
+#include "set.h"
+
+struct sd_device {
+        uint64_t n_ref;
+
+        sd_device *parent;
+        bool parent_set; /* no need to try to reload parent */
+
+        OrderedHashmap *properties;
+        Iterator properties_iterator;
+        uint64_t properties_generation; /* changes whenever the properties are changed */
+        uint64_t properties_iterator_generation; /* generation when iteration was started */
+
+        /* the subset of the properties that should be written to the db*/
+        OrderedHashmap *properties_db;
+
+        Hashmap *sysattr_values; /* cached sysattr values */
+
+        Set *sysattrs; /* names of sysattrs */
+        Iterator sysattrs_iterator;
+        bool sysattrs_read; /* don't try to re-read sysattrs once read */
+
+        Set *tags;
+        Iterator tags_iterator;
+        uint64_t tags_generation; /* changes whenever the tags are changed */
+        uint64_t tags_iterator_generation; /* generation when iteration was started */
+        bool property_tags_outdated; /* need to update TAGS= property */
+
+        Set *devlinks;
+        Iterator devlinks_iterator;
+        uint64_t devlinks_generation; /* changes whenever the devlinks are changed */
+        uint64_t devlinks_iterator_generation; /* generation when iteration was started */
+        bool property_devlinks_outdated; /* need to update DEVLINKS= property */
+        int devlink_priority;
+
+        char **properties_strv; /* the properties hashmap as a strv */
+        uint8_t *properties_nulstr; /* the same as a nulstr */
+        size_t properties_nulstr_len;
+        bool properties_buf_outdated; /* need to reread hashmap */
+
+        int watch_handle;
+
+        char *syspath;
+        const char *devpath;
+        const char *sysnum;
+        char *sysname;
+        bool sysname_set; /* don't reread sysname */
+
+        char *devtype;
+        int ifindex;
+        char *devname;
+        dev_t devnum;
+
+        char *subsystem;
+        bool subsystem_set; /* don't reread subsystem */
+        char *driver;
+        bool driver_set; /* don't reread driver */
+
+        char *id_filename;
+
+        bool is_initialized;
+        uint64_t usec_initialized;
+
+        mode_t devmode;
+        uid_t devuid;
+        gid_t devgid;
+
+        bool uevent_loaded; /* don't reread uevent */
+        bool db_loaded; /* don't reread db */
+
+        bool sealed; /* don't read more information from uevent/db */
+        bool db_persist; /* don't clean up the db when switching from initrd to real root */
+};
+
+typedef enum DeviceAction {
+        DEVICE_ACTION_ADD,
+        DEVICE_ACTION_REMOVE,
+        DEVICE_ACTION_CHANGE,
+        DEVICE_ACTION_MOVE,
+        DEVICE_ACTION_ONLINE,
+        DEVICE_ACTION_OFFLINE,
+        _DEVICE_ACTION_MAX,
+        _DEVICE_ACTION_INVALID = -1,
+} DeviceAction;
+
+int device_new_aux(sd_device **ret);
+int device_add_property_aux(sd_device *device, const char *key, const char *value, bool db);
+int device_add_property_internal(sd_device *device, const char *key, const char *value);
+int device_read_uevent_file(sd_device *device);
+
+int device_set_syspath(sd_device *device, const char *_syspath, bool verify);
+int device_set_ifindex(sd_device *device, const char *ifindex);
+int device_set_devmode(sd_device *device, const char *devmode);
+int device_set_devname(sd_device *device, const char *_devname);
+int device_set_devtype(sd_device *device, const char *_devtype);
+int device_set_devnum(sd_device *device, const char *major, const char *minor);
+int device_set_subsystem(sd_device *device, const char *_subsystem);
+int device_set_driver(sd_device *device, const char *_driver);
+int device_set_usec_initialized(sd_device *device, const char *initialized);
+
+DeviceAction device_action_from_string(const char *s) _pure_;
+const char *device_action_to_string(DeviceAction a) _const_;
diff --git a/src/libsystemd/sd-device/device-private.c b/src/libsystemd/sd-device/device-private.c
new file mode 100644
index 0000000000..81b0b6dde6
--- /dev/null
+++ b/src/libsystemd/sd-device/device-private.c
@@ -0,0 +1,1101 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
+  Copyright 2014 Tom Gundersen <teg@jklm.no>
+
+  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.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <ctype.h>
+#include <sys/types.h>
+#include <net/if.h>
+
+#include "util.h"
+#include "macro.h"
+#include "refcnt.h"
+#include "path-util.h"
+#include "strxcpyx.h"
+#include "fileio.h"
+#include "hashmap.h"
+#include "set.h"
+#include "strv.h"
+#include "mkdir.h"
+
+#include "sd-device.h"
+
+#include "device-util.h"
+#include "device-internal.h"
+#include "device-private.h"
+
+int device_add_property(sd_device *device, const char *key, const char *value) {
+        int r;
+
+        assert(device);
+        assert(key);
+
+        r = device_add_property_aux(device, key, value, false);
+        if (r < 0)
+                return r;
+
+        if (key[0] != '.') {
+                r = device_add_property_aux(device, key, value, true);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int device_add_property_internal_from_string(sd_device *device, const char *str) {
+        _cleanup_free_ char *key = NULL;
+        char *value;
+
+        assert(device);
+        assert(str);
+
+        key = strdup(str);
+        if (!key)
+                return -ENOMEM;
+
+        value = strchr(key, '=');
+        if (!value)
+                return -EINVAL;
+
+        *value = '\0';
+
+        if (isempty(++value))
+                value = NULL;
+
+        return device_add_property_internal(device, key, value);
+}
+
+static int handle_db_line(sd_device *device, char key, const char *value) {
+        char *path;
+        int r;
+
+        assert(device);
+        assert(value);
+
+        switch (key) {
+        case 'S':
+                path = strjoina("/dev/", value);
+                r = device_add_devlink(device, path);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'L':
+                r = safe_atoi(value, &device->devlink_priority);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'E':
+                r = device_add_property_internal_from_string(device, value);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'G':
+                r = device_add_tag(device, value);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'W':
+                r = safe_atoi(value, &device->watch_handle);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'I':
+                r = device_set_usec_initialized(device, value);
+                if (r < 0)
+                        return r;
+
+                break;
+        default:
+                log_debug("device db: unknown key '%c'", key);
+        }
+
+        return 0;
+}
+
+void device_set_devlink_priority(sd_device *device, int priority) {
+        assert(device);
+
+        device->devlink_priority = priority;
+}
+
+void device_set_is_initialized(sd_device *device) {
+        assert(device);
+
+        device->is_initialized = true;
+}
+
+int device_ensure_usec_initialized(sd_device *device, sd_device *device_old) {
+        char num[DECIMAL_STR_MAX(usec_t)];
+        usec_t usec_initialized;
+        int r;
+
+        assert(device);
+
+        if (device_old && device_old->usec_initialized > 0)
+                usec_initialized = device_old->usec_initialized;
+        else
+                usec_initialized = now(CLOCK_MONOTONIC);
+
+        r = snprintf(num, sizeof(num), USEC_FMT, usec_initialized);
+        if (r < 0)
+                return -errno;
+
+        r = device_set_usec_initialized(device, num);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static int device_read_db(sd_device *device) {
+        _cleanup_free_ char *db = NULL;
+        char *path;
+        const char *id, *value;
+        char key;
+        size_t db_len;
+        unsigned i;
+        int r;
+
+        enum {
+                PRE_KEY,
+                KEY,
+                PRE_VALUE,
+                VALUE,
+                INVALID_LINE,
+        } state = PRE_KEY;
+
+        assert(device);
+
+        if (device->db_loaded || device->sealed)
+                return 0;
+
+        r = device_get_id_filename(device, &id);
+        if (r < 0)
+                return r;
+
+        path = strjoina("/run/udev/data/", id);
+
+        r = read_full_file(path, &db, &db_len);
+        if (r < 0) {
+                if (r == -ENOENT)
+                        return 0;
+                else {
+                        log_debug("sd-device: failed to read db '%s': %s", path, strerror(-r));
+                        return r;
+                }
+        }
+
+        /* devices with a database entry are initialized */
+        device_set_is_initialized(device);
+
+        for (i = 0; i < db_len; i++) {
+                switch (state) {
+                case PRE_KEY:
+                        if (!strchr(NEWLINE, db[i])) {
+                                key = db[i];
+
+                                state = KEY;
+                        }
+
+                        break;
+                case KEY:
+                        if (db[i] != ':') {
+                                log_debug("sd-device: ignoring invalid db entry with key '%c'", key);
+
+                                state = INVALID_LINE;
+                        } else {
+                                db[i] = '\0';
+
+                                state = PRE_VALUE;
+                        }
+
+                        break;
+                case PRE_VALUE:
+                        value = &db[i];
+
+                        state = VALUE;
+
+                        break;
+                case INVALID_LINE:
+                        if (strchr(NEWLINE, db[i]))
+                                state = PRE_KEY;
+
+                        break;
+                case VALUE:
+                        if (strchr(NEWLINE, db[i])) {
+                                db[i] = '\0';
+                                r = handle_db_line(device, key, value);
+                                if (r < 0)
+                                        log_debug("sd-device: failed to handle db entry '%c:%s': %s", key, value, strerror(-r));
+
+                                state = PRE_KEY;
+                        }
+
+                        break;
+                default:
+                        assert_not_reached("invalid state when parsing db");
+                }
+        }
+
+        device->db_loaded = true;
+
+        return 0;
+}
+
+uint64_t device_get_properties_generation(sd_device *device) {
+        assert(device);
+
+        return device->properties_generation;
+}
+
+uint64_t device_get_tags_generation(sd_device *device) {
+        assert(device);
+
+        return device->tags_generation;
+}
+
+uint64_t device_get_devlinks_generation(sd_device *device) {
+        assert(device);
+
+        return device->devlinks_generation;
+}
+
+int device_get_devnode_mode(sd_device *device, mode_t *mode) {
+        int r;
+
+        assert(device);
+        assert(mode);
+
+        r = device_read_db(device);
+        if (r < 0)
+                return r;
+
+        *mode = device->devmode;
+
+        return 0;
+}
+
+int device_get_devnode_uid(sd_device *device, uid_t *uid) {
+        int r;
+
+        assert(device);
+        assert(uid);
+
+        r = device_read_db(device);
+        if (r < 0)
+                return r;
+
+        *uid = device->devuid;
+
+        return 0;
+}
+
+static int device_set_devuid(sd_device *device, const char *uid) {
+        unsigned u;
+        int r;
+
+        assert(device);
+        assert(uid);
+
+        r = safe_atou(uid, &u);
+        if (r < 0)
+                return r;
+
+        r = device_add_property_internal(device, "DEVUID", uid);
+        if (r < 0)
+                return r;
+
+        device->devuid = u;
+
+        return 0;
+}
+
+int device_get_devnode_gid(sd_device *device, gid_t *gid) {
+        int r;
+
+        assert(device);
+        assert(gid);
+
+        r = device_read_db(device);
+        if (r < 0)
+                return r;
+
+        *gid = device->devgid;
+
+        return 0;
+}
+
+static int device_set_devgid(sd_device *device, const char *gid) {
+        unsigned g;
+        int r;
+
+        assert(device);
+        assert(gid);
+
+        r = safe_atou(gid, &g);
+        if (r < 0)
+                return r;
+
+        r = device_add_property_internal(device, "DEVGID", gid);
+        if (r < 0)
+                return r;
+
+        device->devgid = g;
+
+        return 0;
+}
+
+static int device_ammend(sd_device *device, const char *key, const char *value) {
+        int r;
+
+        assert(device);
+        assert(key);
+        assert(value);
+
+        if (streq(key, "DEVPATH")) {
+                char *path;
+
+                path = strjoina("/sys", value);
+
+                /* the caller must verify or trust this data (e.g., if it comes from the kernel) */
+                r = device_set_syspath(device, path, false);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set syspath to '%s': %m", path);
+        } else if (streq(key, "SUBSYSTEM")) {
+                r = device_set_subsystem(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set subsystem to '%s': %m", value);
+        } else if (streq(key, "DEVTYPE")) {
+                r = device_set_devtype(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set devtype to '%s': %m", value);
+        } else if (streq(key, "DEVNAME")) {
+                r = device_set_devname(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set devname to '%s': %m", value);
+        } else if (streq(key, "USEC_INITIALIZED")) {
+                r = device_set_usec_initialized(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set usec-initialized to '%s': %m", value);
+        } else if (streq(key, "DRIVER")) {
+                r = device_set_driver(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set driver to '%s': %m", value);
+        } else if (streq(key, "IFINDEX")) {
+                r = device_set_ifindex(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set ifindex to '%s': %m", value);
+        } else if (streq(key, "DEVMODE")) {
+                r = device_set_devmode(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set devmode to '%s': %m", value);
+        } else if (streq(key, "DEVUID")) {
+                r = device_set_devuid(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set devuid to '%s': %m", value);
+        } else if (streq(key, "DEVGID")) {
+                r = device_set_devgid(device, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set devgid to '%s': %m", value);
+        } else if (streq(key, "DEVLINKS")) {
+                char *devlinks, *next;
+
+                devlinks = strdupa(value);
+
+                while ((next = strchr(devlinks, ' '))) {
+                        next[0] = '\0';
+
+                        r = device_add_devlink(device, devlinks);
+                        if (r < 0)
+                                return log_debug_errno(r, "sd-device: could not add devlink '%s': %m", devlinks);
+
+                        devlinks = next + 1;
+                }
+        } else if (streq(key, "TAGS")) {
+                char *tags, *next;
+
+                tags = strdupa(value);
+
+                while ((next = strchr(tags, ':'))) {
+                        next[0] = '\0';
+
+                        r = device_add_tag(device, tags);
+                        if (r < 0)
+                                return log_debug_errno(r, "sd-device: could not add tag '%s': %m", tags);
+
+                        tags = next + 1;
+                }
+        } else {
+                r = device_add_property_internal(device, key, value);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not add property '%s=%s': %m", key, value);
+        }
+
+        return 0;
+}
+
+static const char* const device_action_table[_DEVICE_ACTION_MAX] = {
+        [DEVICE_ACTION_ADD] = "add",
+        [DEVICE_ACTION_REMOVE] = "remove",
+        [DEVICE_ACTION_CHANGE] = "change",
+        [DEVICE_ACTION_MOVE] = "move",
+        [DEVICE_ACTION_ONLINE] = "online",
+        [DEVICE_ACTION_OFFLINE] = "offline",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(device_action, DeviceAction);
+
+static int device_append(sd_device *device, char *key, const char **_major, const char **_minor, uint64_t *_seqnum,
+                         DeviceAction *_action) {
+        DeviceAction action = _DEVICE_ACTION_INVALID;
+        uint64_t seqnum = 0;
+        const char *major = NULL, *minor = NULL;
+        char *value;
+        int r;
+
+        assert(device);
+        assert(key);
+        assert(_major);
+        assert(_minor);
+        assert(_seqnum);
+        assert(_action);
+
+        value = strchr(key, '=');
+        if (!value) {
+                log_debug("sd-device: not a key-value pair: '%s'", key);
+                return -EINVAL;
+        }
+
+        *value = '\0';
+
+        value++;
+
+        if (streq(key, "MAJOR"))
+                major = value;
+        else if (streq(key, "MINOR"))
+                minor = value;
+        else {
+                if (streq(key, "ACTION")) {
+                        action = device_action_from_string(value);
+                        if (action == _DEVICE_ACTION_INVALID)
+                                return -EINVAL;
+                } else if (streq(key, "SEQNUM")) {
+                        r = safe_atou64(value, &seqnum);
+                        if (r < 0)
+                                return r;
+                        else if (seqnum == 0)
+                                 /* kernel only sends seqnum > 0 */
+                                return -EINVAL;
+                }
+
+                r = device_ammend(device, key, value);
+                if (r < 0)
+                        return r;
+        }
+
+        if (major != 0)
+                *_major = major;
+
+        if (minor != 0)
+                *_minor = minor;
+
+        if (action != _DEVICE_ACTION_INVALID)
+                *_action = action;
+
+        if (seqnum > 0)
+                *_seqnum = seqnum;
+
+        return 0;
+}
+
+void device_seal(sd_device *device) {
+        assert(device);
+
+        device->sealed = true;
+}
+
+static int device_verify(sd_device *device, DeviceAction action, uint64_t seqnum) {
+        assert(device);
+
+        if (!device->devpath || !device->subsystem || action == _DEVICE_ACTION_INVALID || seqnum == 0) {
+                log_debug("sd-device: device created from strv lacks devpath, subsystem, action or seqnum");
+                return -EINVAL;
+        }
+
+        device->sealed = true;
+
+        return 0;
+}
+
+int device_new_from_strv(sd_device **ret, char **strv) {
+        _cleanup_device_unref_ sd_device *device = NULL;
+        char **key;
+        const char *major = NULL, *minor = NULL;
+        DeviceAction action = _DEVICE_ACTION_INVALID;
+        uint64_t seqnum;
+        int r;
+
+        assert(ret);
+        assert(strv);
+
+        r = device_new_aux(&device);
+        if (r < 0)
+                return r;
+
+        STRV_FOREACH(key, strv) {
+                r = device_append(device, *key, &major, &minor, &seqnum, &action);
+                if (r < 0)
+                        return r;
+        }
+
+        if (major) {
+                r = device_set_devnum(device, major, minor);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set devnum %s:%s: %m", major, minor);
+        }
+
+        r = device_verify(device, action, seqnum);
+        if (r < 0)
+                return r;
+
+        *ret = device;
+        device = NULL;
+
+        return 0;
+}
+
+int device_new_from_nulstr(sd_device **ret, uint8_t *nulstr, size_t len) {
+        _cleanup_device_unref_ sd_device *device = NULL;
+        const char *major = NULL, *minor = NULL;
+        DeviceAction action = _DEVICE_ACTION_INVALID;
+        uint64_t seqnum;
+        unsigned i = 0;
+        int r;
+
+        assert(ret);
+        assert(nulstr);
+        assert(len);
+
+        r = device_new_aux(&device);
+        if (r < 0)
+                return r;
+
+        while (i < len) {
+                char *key;
+                const char *end;
+
+                key = (char*)&nulstr[i];
+                end = memchr(key, '\0', len - i);
+                if (!end) {
+                        log_debug("sd-device: failed to parse nulstr");
+                        return -EINVAL;
+                }
+                i += end - key + 1;
+
+                r = device_append(device, key, &major, &minor, &seqnum, &action);
+                if (r < 0)
+                        return r;
+        }
+
+        if (major) {
+                r = device_set_devnum(device, major, minor);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: could not set devnum %s:%s: %m", major, minor);
+        }
+
+        r = device_verify(device, action, seqnum);
+        if (r < 0)
+                return r;
+
+        *ret = device;
+        device = NULL;
+
+        return 0;
+}
+
+static int device_update_properties_bufs(sd_device *device) {
+        const char *val, *prop;
+        char **buf_strv = NULL;
+        uint8_t *buf_nulstr = NULL;
+        size_t allocated_nulstr = 0, allocated_strv = 0;
+        size_t nulstr_len = 0, strv_size = 0;
+
+        assert(device);
+
+        FOREACH_DEVICE_PROPERTY(device, prop, val) {
+                size_t len = 0;
+
+                len = strlen(prop) + 1 + strlen(val);
+
+                buf_nulstr = GREEDY_REALLOC0(buf_nulstr, allocated_nulstr, nulstr_len + len + 2);
+                if (!buf_nulstr)
+                        return -ENOMEM;
+
+                buf_strv = GREEDY_REALLOC0(buf_strv, allocated_strv, strv_size + 2);
+                if (!buf_strv)
+                        return -ENOMEM;
+
+                buf_strv[++ strv_size] = (char *)&buf_nulstr[nulstr_len];
+                strscpyl((char *)buf_nulstr + nulstr_len, len + 1, prop, "=", val, NULL);
+                nulstr_len += len + 1;
+        }
+
+        free(device->properties_nulstr);
+        free(device->properties_strv);
+        device->properties_nulstr = buf_nulstr;
+        device->properties_nulstr_len = nulstr_len;
+        device->properties_strv = buf_strv;
+
+        device->properties_buf_outdated = false;
+
+        return 0;
+}
+
+int device_get_properties_nulstr(sd_device *device, const uint8_t **nulstr, size_t *len) {
+        int r;
+
+        assert(device);
+        assert(nulstr);
+        assert(len);
+
+        if (device->properties_buf_outdated) {
+                r = device_update_properties_bufs(device);
+                if (r < 0)
+                        return r;
+        }
+
+        *nulstr = device->properties_nulstr;
+        *len = device->properties_nulstr_len;
+
+        return 0;
+}
+
+int device_get_properties_strv(sd_device *device, char ***strv) {
+        int r;
+
+        assert(device);
+        assert(strv);
+
+        r = device_update_properties_bufs(device);
+        if (r < 0)
+                return r;
+
+        *strv = device->properties_strv;
+
+        return 0;
+}
+
+int device_get_devlink_priority(sd_device *device, int *priority) {
+        int r;
+
+        assert(device);
+        assert(priority);
+
+        r = device_read_db(device);
+        if (r < 0)
+                return r;
+
+        *priority = device->devlink_priority;
+
+        return 0;
+}
+
+int device_get_watch_handle(sd_device *device, int *handle) {
+        int r;
+
+        assert(device);
+        assert(handle);
+
+        r = device_read_db(device);
+        if (r < 0)
+                return r;
+
+        *handle = device->watch_handle;
+
+        return 0;
+}
+
+void device_set_watch_handle(sd_device *device, int handle) {
+        assert(device);
+
+        device->watch_handle = handle;
+}
+
+int device_rename(sd_device *device, const char *name) {
+        _cleanup_free_ char *dirname = NULL;
+        char *new_syspath;
+        const char *interface;
+        int r;
+
+        assert(device);
+        assert(name);
+
+        dirname = dirname_malloc(device->syspath);
+        if (!dirname)
+                return -ENOMEM;
+
+        new_syspath = strjoina(dirname, "/", name);
+
+        /* the user must trust that the new name is correct */
+        r = device_set_syspath(device, new_syspath, false);
+        if (r < 0)
+                return r;
+
+        r = sd_device_get_property_value(device, "INTERFACE", &interface);
+        if (r >= 0) {
+                r = device_add_property_internal(device, "INTERFACE", name);
+                if (r < 0)
+                        return r;
+
+                /* like DEVPATH_OLD, INTERFACE_OLD is not saved to the db, but only stays around for the current event */
+                r = device_add_property_internal(device, "INTERFACE_OLD", interface);
+                if (r < 0)
+                        return r;
+        } else if (r != -ENOENT)
+                return r;
+
+        return 0;
+}
+
+int device_shallow_clone(sd_device *old_device, sd_device **new_device) {
+        _cleanup_device_unref_ sd_device *ret = NULL;
+        int r;
+
+        assert(old_device);
+        assert(new_device);
+
+        r = device_new_aux(&ret);
+        if (r < 0)
+                return r;
+
+        r = device_set_syspath(ret, old_device->syspath, false);
+        if (r < 0)
+                return r;
+
+        r = device_set_subsystem(ret, old_device->subsystem);
+        if (r < 0)
+                return r;
+
+        ret->devnum = old_device->devnum;
+
+        *new_device = ret;
+        ret = NULL;
+
+        return 0;
+}
+
+int device_clone_with_db(sd_device *old_device, sd_device **new_device) {
+        _cleanup_device_unref_ sd_device *ret = NULL;
+        int r;
+
+        assert(old_device);
+        assert(new_device);
+
+        r = device_shallow_clone(old_device, &ret);
+        if (r < 0)
+                return r;
+
+        r = device_read_db(ret);
+        if (r < 0)
+                return r;
+
+        ret->sealed = true;
+
+        *new_device = ret;
+        ret = NULL;
+
+        return 0;
+}
+
+int device_new_from_synthetic_event(sd_device **new_device, const char *syspath, const char *action) {
+        _cleanup_device_unref_ sd_device *ret = NULL;
+        int r;
+
+        assert(new_device);
+        assert(syspath);
+        assert(action);
+
+        r = sd_device_new_from_syspath(&ret, syspath);
+        if (r < 0)
+                return r;
+
+        r = device_read_uevent_file(ret);
+        if (r < 0)
+                return r;
+
+        r = device_add_property_internal(ret, "ACTION", action);
+        if (r < 0)
+                return r;
+
+        *new_device = ret;
+        ret = NULL;
+
+        return 0;
+}
+
+int device_copy_properties(sd_device *device_dst, sd_device *device_src) {
+        const char *property, *value;
+        int r;
+
+        assert(device_dst);
+        assert(device_src);
+
+        FOREACH_DEVICE_PROPERTY(device_src, property, value) {
+                r = device_add_property(device_dst, property, value);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+void device_cleanup_tags(sd_device *device) {
+        assert(device);
+
+        set_free_free(device->tags);
+        device->tags = NULL;
+        device->property_tags_outdated = true;
+        device->tags_generation ++;
+}
+
+void device_cleanup_devlinks(sd_device *device) {
+        assert(device);
+
+        set_free_free(device->devlinks);
+        device->devlinks = NULL;
+        device->property_devlinks_outdated = true;
+        device->devlinks_generation ++;
+}
+
+void device_remove_tag(sd_device *device, const char *tag) {
+        assert(device);
+        assert(tag);
+
+        free(set_remove(device->tags, tag));
+        device->property_tags_outdated = true;
+        device->tags_generation ++;
+}
+
+static int device_tag(sd_device *device, const char *tag, bool add) {
+        const char *id;
+        char *path;
+        int r;
+
+        assert(device);
+        assert(tag);
+
+        r = device_get_id_filename(device, &id);
+        if (r < 0)
+                return r;
+
+        path = strjoina("/run/udev/tags/", tag, "/", id);
+
+        if (add) {
+                r = touch_file(path, true, USEC_INFINITY, UID_INVALID, GID_INVALID, 0444);
+                if (r < 0)
+                        return r;
+        } else {
+                r = unlink(path);
+                if (r < 0 && errno != ENOENT)
+                        return -errno;
+        }
+
+        return 0;
+}
+
+int device_tag_index(sd_device *device, sd_device *device_old, bool add) {
+        const char *tag;
+        int r = 0, k;
+
+        if (add && device_old) {
+                /* delete possible left-over tags */
+                FOREACH_DEVICE_TAG(device_old, tag) {
+                        if (!sd_device_has_tag(device, tag)) {
+                                k = device_tag(device_old, tag, false);
+                                if (r >= 0 && k < 0)
+                                        r = k;
+                        }
+                }
+        }
+
+        FOREACH_DEVICE_TAG(device, tag) {
+                k = device_tag(device, tag, add);
+                if (r >= 0 && k < 0)
+                        r = k;
+        }
+
+        return r;
+}
+
+static bool device_has_info(sd_device *device) {
+        assert(device);
+
+        if (!set_isempty(device->devlinks))
+                return true;
+
+        if (device->devlink_priority != 0)
+                return true;
+
+        if (!ordered_hashmap_isempty(device->properties_db))
+                return true;
+
+        if (!set_isempty(device->tags))
+                return true;
+
+        if (device->watch_handle >= 0)
+                return true;
+
+        return false;
+}
+
+void device_set_db_persist(sd_device *device) {
+        assert(device);
+
+        device->db_persist = true;
+}
+
+int device_update_db(sd_device *device) {
+        const char *id;
+        char *path;
+        _cleanup_fclose_ FILE *f = NULL;
+        _cleanup_free_ char *path_tmp = NULL;
+        bool has_info;
+        int r;
+
+        assert(device);
+
+        has_info = device_has_info(device);
+
+        r = device_get_id_filename(device, &id);
+        if (r < 0)
+                return r;
+
+        path = strjoina("/run/udev/data/", id);
+
+        /* do not store anything for otherwise empty devices */
+        if (!has_info && major(device->devnum) == 0 && device->ifindex == 0) {
+                r = unlink(path);
+                if (r < 0 && errno != ENOENT)
+                        return -errno;
+
+                return 0;
+        }
+
+        /* write a database file */
+        r = mkdir_parents(path, 0755);
+        if (r < 0)
+                return r;
+
+        r = fopen_temporary(path, &f, &path_tmp);
+        if (r < 0)
+                return r;
+
+        /*
+         * set 'sticky' bit to indicate that we should not clean the
+         * database when we transition from initramfs to the real root
+         */
+        if (device->db_persist) {
+                r = fchmod(fileno(f), 01644);
+                if (r < 0) {
+                        r = -errno;
+                        goto fail;
+                }
+        } else {
+                r = fchmod(fileno(f), 0644);
+                if (r < 0) {
+                        r = -errno;
+                        goto fail;
+                }
+        }
+
+        if (has_info) {
+                const char *property, *value, *tag;
+                Iterator i;
+
+                if (major(device->devnum) > 0) {
+                        const char *devlink;
+
+                        FOREACH_DEVICE_DEVLINK(device, devlink)
+                                fprintf(f, "S:%s\n", devlink + strlen("/dev/"));
+
+                        if (device->devlink_priority != 0)
+                                fprintf(f, "L:%i\n", device->devlink_priority);
+
+                        if (device->watch_handle >= 0)
+                                fprintf(f, "W:%i\n", device->watch_handle);
+                }
+
+                if (device->usec_initialized > 0)
+                        fprintf(f, "I:"USEC_FMT"\n", device->usec_initialized);
+
+                ORDERED_HASHMAP_FOREACH_KEY(value, property, device->properties_db, i)
+                        fprintf(f, "E:%s=%s\n", property, value);
+
+                FOREACH_DEVICE_TAG(device, tag)
+                        fprintf(f, "G:%s\n", tag);
+        }
+
+        r = fflush_and_check(f);
+        if (r < 0)
+                goto fail;
+
+        r = rename(path_tmp, path);
+        if (r < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        log_debug("created %s file '%s' for '%s'", has_info ? "db" : "empty",
+                  path, device->devpath);
+
+        return 0;
+
+fail:
+        log_error_errno(r, "failed to create %s file '%s' for '%s'", has_info ? "db" : "empty",
+                        path, device->devpath);
+        unlink(path);
+        unlink(path_tmp);
+
+        return r;
+}
+
+int device_delete_db(sd_device *device) {
+        const char *id;
+        char *path;
+        int r;
+
+        assert(device);
+
+        r = device_get_id_filename(device, &id);
+        if (r < 0)
+                return r;
+
+        path = strjoina("/run/udev/data/", id);
+
+        r = unlink(path);
+        if (r < 0 && errno != ENOENT)
+                return -errno;
+
+        return 0;
+}
diff --git a/src/libsystemd/sd-device/device-private.h b/src/libsystemd/sd-device/device-private.h
new file mode 100644
index 0000000000..7c6219ca6c
--- /dev/null
+++ b/src/libsystemd/sd-device/device-private.h
@@ -0,0 +1,63 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Tom Gundersen <teg@jklm.no>
+
+  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.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+int device_new_from_nulstr(sd_device **ret, uint8_t *nulstr, size_t len);
+int device_new_from_strv(sd_device **ret, char **strv);
+
+int device_get_id_filename(sd_device *device, const char **ret);
+
+int device_get_devlink_priority(sd_device *device, int *priority);
+int device_get_watch_handle(sd_device *device, int *handle);
+int device_get_devnode_mode(sd_device *device, mode_t *mode);
+int device_get_devnode_uid(sd_device *device, uid_t *uid);
+int device_get_devnode_gid(sd_device *device, gid_t *gid);
+
+void device_seal(sd_device *device);
+void device_set_is_initialized(sd_device *device);
+void device_set_watch_handle(sd_device *device, int fd);
+void device_set_db_persist(sd_device *device);
+void device_set_devlink_priority(sd_device *device, int priority);
+int device_ensure_usec_initialized(sd_device *devcie, sd_device *device_old);
+int device_add_devlink(sd_device *device, const char *devlink);
+int device_add_property(sd_device *device, const char *property, const char *value);
+int device_add_tag(sd_device *device, const char *tag);
+void device_remove_tag(sd_device *device, const char *tag);
+void device_cleanup_tags(sd_device *device);
+void device_cleanup_devlinks(sd_device *device);
+
+uint64_t device_get_properties_generation(sd_device *device);
+uint64_t device_get_tags_generation(sd_device *device);
+uint64_t device_get_devlinks_generation(sd_device *device);
+
+int device_get_properties_nulstr(sd_device *device, const uint8_t **nulstr, size_t *len);
+int device_get_properties_strv(sd_device *device, char ***strv);
+
+int device_rename(sd_device *device, const char *name);
+int device_shallow_clone(sd_device *old_device, sd_device **new_device);
+int device_clone_with_db(sd_device *old_device, sd_device **new_device);
+int device_copy_properties(sd_device *device_dst, sd_device *device_src);
+int device_new_from_synthetic_event(sd_device **new_device, const char *syspath, const char *action);
+
+int device_tag_index(sd_device *dev, sd_device *dev_old, bool add);
+int device_update_db(sd_device *device);
+int device_delete_db(sd_device *device);
diff --git a/src/libsystemd/sd-device/device-util.h b/src/libsystemd/sd-device/device-util.h
new file mode 100644
index 0000000000..bfbb3284a8
--- /dev/null
+++ b/src/libsystemd/sd-device/device-util.h
@@ -0,0 +1,48 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Tom Gundersen <teg@jklm.no>
+
+  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.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "util.h"
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(sd_device*, sd_device_unref);
+
+#define _cleanup_device_unref_ _cleanup_(sd_device_unrefp)
+
+#define FOREACH_DEVICE_PROPERTY(device, key, value)                \
+        for (key = sd_device_get_property_first(device, &(value)); \
+             key;                                                  \
+             key = sd_device_get_property_next(device, &(value)))
+
+#define FOREACH_DEVICE_TAG(device, tag)             \
+        for (tag = sd_device_get_tag_first(device); \
+             tag;                                   \
+             tag = sd_device_get_tag_next(device))
+
+#define FOREACH_DEVICE_SYSATTR(device, attr)             \
+        for (attr = sd_device_get_sysattr_first(device); \
+             attr;                                       \
+             attr = sd_device_get_sysattr_next(device))
+
+#define FOREACH_DEVICE_DEVLINK(device, devlink)             \
+        for (devlink = sd_device_get_devlink_first(device); \
+             devlink;                                   \
+             devlink = sd_device_get_devlink_next(device))
diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
new file mode 100644
index 0000000000..da1052c8fb
--- /dev/null
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -0,0 +1,1812 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
+  Copyright 2014 Tom Gundersen <teg@jklm.no>
+
+  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.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <ctype.h>
+#include <sys/types.h>
+#include <net/if.h>
+
+#include "util.h"
+#include "macro.h"
+#include "path-util.h"
+#include "strxcpyx.h"
+#include "fileio.h"
+#include "hashmap.h"
+#include "set.h"
+#include "strv.h"
+
+#include "sd-device.h"
+
+#include "device-util.h"
+#include "device-private.h"
+#include "device-internal.h"
+
+int device_new_aux(sd_device **ret) {
+        _cleanup_device_unref_ sd_device *device = NULL;
+
+        assert(ret);
+
+        device = new0(sd_device, 1);
+        if (!device)
+                return -ENOMEM;
+
+        device->n_ref = 1;
+        device->watch_handle = -1;
+
+        *ret = device;
+        device = NULL;
+
+        return 0;
+}
+
+_public_ sd_device *sd_device_ref(sd_device *device) {
+        if (device)
+                assert_se(++ device->n_ref >= 2);
+
+        return device;
+}
+
+_public_ sd_device *sd_device_unref(sd_device *device) {
+        if (device && -- device->n_ref == 0) {
+                sd_device_unref(device->parent);
+                free(device->syspath);
+                free(device->sysname);
+                free(device->devtype);
+                free(device->devname);
+                free(device->subsystem);
+                free(device->driver);
+                free(device->id_filename);
+                free(device->properties_strv);
+                free(device->properties_nulstr);
+
+                ordered_hashmap_free_free_free(device->properties);
+                ordered_hashmap_free_free_free(device->properties_db);
+                hashmap_free_free_free(device->sysattr_values);
+                set_free_free(device->sysattrs);
+                set_free_free(device->tags);
+                set_free_free(device->devlinks);
+
+                free(device);
+        }
+
+        return NULL;
+}
+
+int device_add_property_aux(sd_device *device, const char *_key, const char *_value, bool db) {
+        OrderedHashmap **properties;
+
+        assert(device);
+        assert(_key);
+
+        if (db)
+                properties = &device->properties_db;
+        else
+                properties = &device->properties;
+
+        if (_value) {
+                _cleanup_free_ char *key = NULL, *value = NULL, *old_key = NULL, *old_value = NULL;
+                int r;
+
+                r = ordered_hashmap_ensure_allocated(properties, &string_hash_ops);
+                if (r < 0)
+                        return r;
+
+                key = strdup(_key);
+                if (!key)
+                        return -ENOMEM;
+
+                value = strdup(_value);
+                if (!value)
+                        return -ENOMEM;
+
+                old_value = ordered_hashmap_get2(*properties, key, (void**) &old_key);
+
+                r = ordered_hashmap_replace(*properties, key, value);
+                if (r < 0)
+                        return r;
+
+                key = NULL;
+                value = NULL;
+        } else {
+                _cleanup_free_ char *key = NULL;
+                _cleanup_free_ char *value = NULL;
+
+                value = ordered_hashmap_remove2(*properties, _key, (void**) &key);
+        }
+
+        if (!db) {
+                device->properties_generation ++;
+                device->properties_buf_outdated = true;
+        }
+
+        return 0;
+}
+
+int device_add_property_internal(sd_device *device, const char *key, const char *value) {
+        return device_add_property_aux(device, key, value, false);
+}
+
+int device_set_syspath(sd_device *device, const char *_syspath, bool verify) {
+        _cleanup_free_ char *syspath = NULL;
+        const char *devpath;
+        int r;
+
+        assert(device);
+        assert(_syspath);
+
+        /* must be a subdirectory of /sys */
+        if (!path_startswith(_syspath, "/sys/")) {
+                log_debug("sd-device: syspath '%s' is not a subdirectory of /sys", _syspath);
+                return -EINVAL;
+        }
+
+        if (verify) {
+                r = readlink_and_canonicalize(_syspath, &syspath);
+                if (r == -EINVAL) {
+                        /* not a symlink */
+                        syspath = canonicalize_file_name(_syspath);
+                        if (!syspath) {
+                                log_debug("sd-device: could not canonicalize '%s': %m", _syspath);
+                                return -errno;
+                        }
+                /* ignore errors due to the link not being a symlink */
+                } else if (r < 0 && r != -EINVAL) {
+                        log_debug("sd-device: could not get target of '%s': %s", _syspath, strerror(-r));
+                        return r;
+                }
+
+                if (path_startswith(syspath,  "/sys/devices/")) {
+                        char *path;
+
+                        /* all 'devices' require an 'uevent' file */
+                        path = strjoina(syspath, "/uevent");
+                        r = access(path, F_OK);
+                        if (r < 0) {
+                                log_debug("sd-device: %s does not have an uevent file: %m", syspath);
+                                return -errno;
+                        }
+                } else {
+                        /* everything else just just needs to be a directory */
+                        if (!is_dir(syspath, false)) {
+                                log_debug("sd-device: %s is not a directory", syspath);
+                                return -EINVAL;
+                        }
+                }
+        } else {
+                syspath = strdup(_syspath);
+                if (!syspath)
+                        return -ENOMEM;
+        }
+
+        devpath = syspath + strlen("/sys");
+
+        r = device_add_property_internal(device, "DEVPATH", devpath);
+        if (r < 0)
+                return r;
+
+        free(device->syspath);
+        device->syspath = syspath;
+        syspath = NULL;
+
+        device->devpath = devpath;
+
+        return 0;
+}
+
+_public_ int sd_device_new_from_syspath(sd_device **ret, const char *syspath) {
+        _cleanup_device_unref_ sd_device *device = NULL;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(syspath, -EINVAL);
+
+        r = device_new_aux(&device);
+        if (r < 0)
+                return r;
+
+        r = device_set_syspath(device, syspath, true);
+        if (r < 0)
+                return r;
+
+        *ret = device;
+        device = NULL;
+
+        return 0;
+}
+
+_public_ int sd_device_new_from_devnum(sd_device **ret, char type, dev_t devnum) {
+        char *syspath;
+        char id[DECIMAL_STR_MAX(unsigned) * 2 + 1];
+
+        assert_return(ret, -EINVAL);
+        assert_return(type == 'b' || type == 'c', -EINVAL);
+
+        /* use /sys/dev/{block,char}/<maj>:<min> link */
+        snprintf(id, sizeof(id), "%u:%u", major(devnum), minor(devnum));
+
+        syspath = strjoina("/sys/dev/", (type == 'b' ? "block" : "char"), "/", id);
+
+        return sd_device_new_from_syspath(ret, syspath);
+}
+
+_public_ int sd_device_new_from_subsystem_sysname(sd_device **ret, const char *subsystem, const char *sysname) {
+        char *syspath;
+
+        assert_return(ret, -EINVAL);
+        assert_return(subsystem, -EINVAL);
+        assert_return(sysname, -EINVAL);
+
+        if (streq(subsystem, "subsystem")) {
+                syspath = strjoina("/sys/subsystem/", sysname);
+                if (access(syspath, F_OK) >= 0)
+                        return sd_device_new_from_syspath(ret, syspath);
+
+                syspath = strjoina("/sys/bus/", sysname);
+                if (access(syspath, F_OK) >= 0)
+                        return sd_device_new_from_syspath(ret, syspath);
+
+                syspath = strjoina("/sys/class/", sysname);
+                if (access(syspath, F_OK) >= 0)
+                        return sd_device_new_from_syspath(ret, syspath);
+        } else  if (streq(subsystem, "module")) {
+                syspath = strjoina("/sys/module/", sysname);
+                if (access(syspath, F_OK) >= 0)
+                        return sd_device_new_from_syspath(ret, syspath);
+        } else if (streq(subsystem, "drivers")) {
+                char subsys[PATH_MAX];
+                char *driver;
+
+                strscpy(subsys, sizeof(subsys), sysname);
+                driver = strchr(subsys, ':');
+                if (driver) {
+                        driver[0] = '\0';
+                        driver++;
+
+                        syspath = strjoina("/sys/subsystem/", subsys, "/drivers/", driver);
+                        if (access(syspath, F_OK) >= 0)
+                                return sd_device_new_from_syspath(ret, syspath);
+
+                        syspath = strjoina("/sys/bus/", subsys, "/drivers/", driver);
+                        if (access(syspath, F_OK) >= 0)
+                                return sd_device_new_from_syspath(ret, syspath);
+                } else
+                        return -EINVAL;
+        } else {
+                syspath = strjoina("/sys/subsystem/", subsystem, "/devices/", sysname);
+                if (access(syspath, F_OK) >= 0)
+                        return sd_device_new_from_syspath(ret, syspath);
+
+                syspath = strjoina("/sys/bus/", subsystem, "/devices/", sysname);
+                if (access(syspath, F_OK) >= 0)
+                        return sd_device_new_from_syspath(ret, syspath);
+
+                syspath = strjoina("/sys/class/", subsystem, "/", sysname);
+                if (access(syspath, F_OK) >= 0)
+                        return sd_device_new_from_syspath(ret, syspath);
+        }
+
+        return -ENOENT;
+}
+
+int device_set_devtype(sd_device *device, const char *_devtype) {
+        _cleanup_free_ char *devtype = NULL;
+        int r;
+
+        assert(device);
+        assert(_devtype);
+
+        devtype = strdup(_devtype);
+        if (!devtype)
+                return -ENOMEM;
+
+        r = device_add_property_internal(device, "DEVTYPE", devtype);
+        if (r < 0)
+                return r;
+
+        free(device->devtype);
+        device->devtype = devtype;
+        devtype = NULL;
+
+        return 0;
+}
+
+int device_set_ifindex(sd_device *device, const char *_ifindex) {
+        int ifindex, r;
+
+        assert(device);
+        assert(_ifindex);
+
+        r = safe_atoi(_ifindex, &ifindex);
+        if (r < 0)
+                return r;
+
+        if (ifindex <= 0)
+                return -EINVAL;
+
+        r = device_add_property_internal(device, "IFINDEX", _ifindex);
+        if (r < 0)
+                return r;
+
+        device->ifindex = ifindex;
+
+        return 0;
+}
+
+int device_set_devname(sd_device *device, const char *_devname) {
+        _cleanup_free_ char *devname = NULL;
+        int r;
+
+        assert(device);
+        assert(_devname);
+
+        if (_devname[0] != '/') {
+                r = asprintf(&devname, "/dev/%s", _devname);
+                if (r < 0)
+                        return -ENOMEM;
+        } else {
+                devname = strdup(_devname);
+                if (!devname)
+                        return -ENOMEM;
+        }
+
+        r = device_add_property_internal(device, "DEVNAME", devname);
+        if (r < 0)
+                return r;
+
+        free(device->devname);
+        device->devname = devname;
+        devname = NULL;
+
+        return 0;
+}
+
+int device_set_devmode(sd_device *device, const char *_devmode) {
+        unsigned devmode;
+        int r;
+
+        assert(device);
+        assert(_devmode);
+
+        r = safe_atou(_devmode, &devmode);
+        if (r < 0)
+                return r;
+
+        if (devmode > 07777)
+                return -EINVAL;
+
+        r = device_add_property_internal(device, "DEVMODE", _devmode);
+        if (r < 0)
+                return r;
+
+        device->devmode = devmode;
+
+        return 0;
+}
+
+int device_set_devnum(sd_device *device, const char *major, const char *minor) {
+        unsigned maj = 0, min = 0;
+        int r;
+
+        assert(device);
+        assert(major);
+
+        r = safe_atou(major, &maj);
+        if (r < 0)
+                return r;
+        if (!maj)
+                return 0;
+
+        if (minor) {
+                r = safe_atou(minor, &min);
+                if (r < 0)
+                        return r;
+        }
+
+        r = device_add_property_internal(device, "MAJOR", major);
+        if (r < 0)
+                return r;
+
+        if (minor) {
+                r = device_add_property_internal(device, "MINOR", minor);
+                if (r < 0)
+                        return r;
+        }
+
+        device->devnum = makedev(maj, min);
+
+        return 0;
+}
+
+static int handle_uevent_line(sd_device *device, const char *key, const char *value, const char **major, const char **minor) {
+        int r;
+
+        assert(device);
+        assert(key);
+        assert(value);
+        assert(major);
+        assert(minor);
+
+        if (streq(key, "DEVTYPE")) {
+                r = device_set_devtype(device, value);
+                if (r < 0)
+                        return r;
+        } else if (streq(key, "IFINDEX")) {
+                r = device_set_ifindex(device, value);
+                if (r < 0)
+                        return r;
+        } else if (streq(key, "DEVNAME")) {
+                r = device_set_devname(device, value);
+                if (r < 0)
+                        return r;
+        } else if (streq(key, "DEVMODE")) {
+                r = device_set_devmode(device, value);
+                if (r < 0)
+                        return r;
+        } else if (streq(key, "MAJOR"))
+                *major = value;
+        else if (streq(key, "MINOR"))
+                *minor = value;
+        else {
+                r = device_add_property_internal(device, key, value);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+int device_read_uevent_file(sd_device *device) {
+        _cleanup_free_ char *uevent = NULL;
+        const char *syspath, *key, *value, *major = NULL, *minor = NULL;
+        char *path;
+        size_t uevent_len;
+        unsigned i;
+        int r;
+
+        enum {
+                PRE_KEY,
+                KEY,
+                PRE_VALUE,
+                VALUE,
+                INVALID_LINE,
+        } state = PRE_KEY;
+
+        assert(device);
+
+        if (device->uevent_loaded || device->sealed)
+                return 0;
+
+        r = sd_device_get_syspath(device, &syspath);
+        if (r < 0)
+                return r;
+
+        path = strjoina(syspath, "/uevent");
+
+        r = read_full_file(path, &uevent, &uevent_len);
+        if (r < 0) {
+                log_debug("sd-device: failed to read uevent file '%s': %s", path, strerror(-r));
+                return r;
+        }
+
+        for (i = 0; i < uevent_len; i++) {
+                switch (state) {
+                case PRE_KEY:
+                        if (!strchr(NEWLINE, uevent[i])) {
+                                key = &uevent[i];
+
+                                state = KEY;
+                        }
+
+                        break;
+                case KEY:
+                        if (uevent[i] == '=') {
+                                uevent[i] = '\0';
+
+                                state = PRE_VALUE;
+                        } else if (strchr(NEWLINE, uevent[i])) {
+                                uevent[i] = '\0';
+                                log_debug("sd-device: ignoring invalid uevent line '%s'", key);
+
+                                state = PRE_KEY;
+                        }
+
+                        break;
+                case PRE_VALUE:
+                        value = &uevent[i];
+
+                        state = VALUE;
+
+                        break;
+                case VALUE:
+                        if (strchr(NEWLINE, uevent[i])) {
+                                uevent[i] = '\0';
+
+                                r = handle_uevent_line(device, key, value, &major, &minor);
+                                if (r < 0)
+                                        log_debug("sd-device: failed to handle uevent entry '%s=%s': %s", key, value, strerror(-r));
+
+                                state = PRE_KEY;
+                        }
+
+                        break;
+                default:
+                        assert_not_reached("invalid state when parsing uevent file");
+                }
+        }
+
+        if (major) {
+                r = device_set_devnum(device, major, minor);
+                if (r < 0)
+                        log_debug("sd-device: could not set 'MAJOR=%s' or 'MINOR=%s' from '%s': %s", major, minor, path, strerror(-r));
+        }
+
+        device->uevent_loaded = true;
+
+        return 0;
+}
+
+_public_ int sd_device_get_ifindex(sd_device *device, int *ifindex) {
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(ifindex, -EINVAL);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        *ifindex = device->ifindex;
+
+        return 0;
+}
+
+_public_ int sd_device_new_from_device_id(sd_device **ret, const char *id) {
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(id, -EINVAL);
+
+        switch (id[0]) {
+        case 'b':
+        case 'c':
+        {
+                char type;
+                int maj, min;
+
+                r = sscanf(id, "%c%i:%i", &type, &maj, &min);
+                if (r != 3)
+                        return -EINVAL;
+
+                return sd_device_new_from_devnum(ret, type, makedev(maj, min));
+        }
+        case 'n':
+        {
+                _cleanup_device_unref_ sd_device *device = NULL;
+                _cleanup_close_ int sk = -1;
+                struct ifreq ifr = {};
+                int ifindex;
+
+                r = safe_atoi(&id[1], &ifr.ifr_ifindex);
+                if (r < 0)
+                        return r;
+                else if (ifr.ifr_ifindex <= 0)
+                        return -EINVAL;
+
+                sk = socket(PF_INET, SOCK_DGRAM, 0);
+                if (sk < 0)
+                        return -errno;
+
+                r = ioctl(sk, SIOCGIFNAME, &ifr);
+                if (r < 0)
+                        return -errno;
+
+                r = sd_device_new_from_subsystem_sysname(&device, "net", ifr.ifr_name);
+                if (r < 0)
+                        return r;
+
+                r = sd_device_get_ifindex(device, &ifindex);
+                if (r < 0)
+                        return r;
+
+                /* this si racey, so we might end up with the wrong device */
+                if (ifr.ifr_ifindex != ifindex)
+                        return -ENODEV;
+
+                *ret = device;
+                device = NULL;
+
+                return 0;
+        }
+        case '+':
+        {
+                char subsys[PATH_MAX];
+                char *sysname;
+
+                (void)strscpy(subsys, sizeof(subsys), id + 1);
+                sysname = strchr(subsys, ':');
+                if (!sysname)
+                        return -EINVAL;
+
+                sysname[0] = '\0';
+                sysname ++;
+
+                return sd_device_new_from_subsystem_sysname(ret, subsys, sysname);
+        }
+        default:
+                return -EINVAL;
+        }
+}
+
+_public_ int sd_device_get_syspath(sd_device *device, const char **ret) {
+        assert_return(device, -EINVAL);
+        assert_return(ret, -EINVAL);
+
+        assert(path_startswith(device->syspath, "/sys/"));
+
+        *ret = device->syspath;
+
+        return 0;
+}
+
+static int device_new_from_child(sd_device **ret, sd_device *child) {
+        _cleanup_free_ char *path = NULL;
+        const char *subdir, *syspath;
+        int r;
+
+        assert(ret);
+        assert(child);
+
+        r = sd_device_get_syspath(child, &syspath);
+        if (r < 0)
+                return r;
+
+        path = strdup(syspath);
+        if (!path)
+                return -ENOMEM;
+        subdir = path + strlen("/sys");
+
+        for (;;) {
+                char *pos;
+
+                pos = strrchr(subdir, '/');
+                if (!pos || pos < subdir + 2)
+                        break;
+
+                *pos = '\0';
+
+                r = sd_device_new_from_syspath(ret, path);
+                if (r < 0)
+                        continue;
+
+                return 0;
+        }
+
+        return -ENOENT;
+}
+
+_public_ int sd_device_get_parent(sd_device *child, sd_device **ret) {
+
+        assert_return(ret, -EINVAL);
+        assert_return(child, -EINVAL);
+
+        if (!child->parent_set) {
+                child->parent_set = true;
+
+                (void)device_new_from_child(&child->parent, child);
+        }
+
+        if (!child->parent)
+                return -ENOENT;
+
+        *ret = child->parent;
+
+        return 0;
+}
+
+int device_set_subsystem(sd_device *device, const char *_subsystem) {
+        _cleanup_free_ char *subsystem = NULL;
+        int r;
+
+        assert(device);
+        assert(_subsystem);
+
+        subsystem = strdup(_subsystem);
+        if (!subsystem)
+                return -ENOMEM;
+
+        r = device_add_property_internal(device, "SUBSYSTEM", subsystem);
+        if (r < 0)
+                return r;
+
+        free(device->subsystem);
+        device->subsystem = subsystem;
+        subsystem = NULL;
+
+        device->subsystem_set = true;
+
+        return 0;
+}
+
+_public_ int sd_device_get_subsystem(sd_device *device, const char **ret) {
+        assert_return(ret, -EINVAL);
+        assert_return(device, -EINVAL);
+
+        if (!device->subsystem_set) {
+                _cleanup_free_ char *subsystem = NULL;
+                const char *syspath;
+                char *path;
+                int r;
+
+                /* read 'subsystem' link */
+                r = sd_device_get_syspath(device, &syspath);
+                if (r < 0)
+                        return r;
+
+                path = strjoina(syspath, "/subsystem");
+                r = readlink_value(path, &subsystem);
+                if (r >= 0)
+                        r = device_set_subsystem(device, subsystem);
+                /* use implicit names */
+                else if (path_startswith(device->devpath, "/module/"))
+                        r = device_set_subsystem(device, "module");
+                else if (strstr(device->devpath, "/drivers/"))
+                        r = device_set_subsystem(device, "drivers");
+                else if (path_startswith(device->devpath, "/subsystem/") ||
+                         path_startswith(device->devpath, "/class/") ||
+                         path_startswith(device->devpath, "/buss/"))
+                        r = device_set_subsystem(device, "subsystem");
+                if (r < 0)
+                        return r;
+
+                device->subsystem_set = true;
+        }
+
+        *ret = device->subsystem;
+
+        return 0;
+}
+
+_public_ int sd_device_get_devtype(sd_device *device, const char **devtype) {
+        int r;
+
+        assert(devtype);
+        assert(device);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        *devtype = device->devtype;
+
+        return 0;
+}
+
+_public_ int sd_device_get_parent_with_subsystem_devtype(sd_device *child, const char *subsystem, const char *devtype, sd_device **ret) {
+        sd_device *parent = NULL;
+        int r;
+
+        assert_return(child, -EINVAL);
+        assert_return(subsystem, -EINVAL);
+
+        r = sd_device_get_parent(child, &parent);
+        while (r >= 0) {
+                const char *parent_subsystem = NULL;
+                const char *parent_devtype = NULL;
+
+                (void)sd_device_get_subsystem(parent, &parent_subsystem);
+                if (streq_ptr(parent_subsystem, subsystem)) {
+                        if (!devtype)
+                                break;
+
+                        (void)sd_device_get_devtype(parent, &parent_devtype);
+                        if (streq_ptr(parent_devtype, devtype))
+                                break;
+                }
+                r = sd_device_get_parent(parent, &parent);
+        }
+
+        if (r < 0)
+                return r;
+
+        *ret = parent;
+
+        return 0;
+}
+
+_public_ int sd_device_get_devnum(sd_device *device, dev_t *devnum) {
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(devnum, -EINVAL);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        *devnum = device->devnum;
+
+        return 0;
+}
+
+int device_set_driver(sd_device *device, const char *_driver) {
+        _cleanup_free_ char *driver = NULL;
+        int r;
+
+        assert(device);
+        assert(_driver);
+
+        driver = strdup(_driver);
+        if (!driver)
+                return -ENOMEM;
+
+        r = device_add_property_internal(device, "DRIVER", driver);
+        if (r < 0)
+                return r;
+
+        free(device->driver);
+        device->driver = driver;
+        driver = NULL;
+
+        device->driver_set = true;
+
+        return 0;
+}
+
+_public_ int sd_device_get_driver(sd_device *device, const char **ret) {
+        assert_return(device, -EINVAL);
+        assert_return(ret, -EINVAL);
+
+        if (!device->driver_set) {
+                _cleanup_free_ char *driver = NULL;
+                const char *syspath;
+                char *path;
+                int r;
+
+                r = sd_device_get_syspath(device, &syspath);
+                if (r < 0)
+                        return r;
+
+                path = strjoina(syspath, "/driver");
+                r = readlink_value(path, &driver);
+                if (r >= 0) {
+                        r = device_set_driver(device, driver);
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        *ret = device->driver;
+
+        return 0;
+}
+
+_public_ int sd_device_get_devpath(sd_device *device, const char **devpath) {
+        assert_return(device, -EINVAL);
+        assert_return(devpath, -EINVAL);
+
+        assert(device->devpath);
+        assert(device->devpath[0] == '/');
+
+        *devpath = device->devpath;
+
+        return 0;
+}
+
+_public_ int sd_device_get_devname(sd_device *device, const char **devname) {
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(devname, -EINVAL);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        if (!device->devname)
+                return -ENOENT;
+
+        assert(path_startswith(device->devname, "/dev/"));
+
+        *devname = device->devname;
+
+        return 0;
+}
+
+static int device_set_sysname(sd_device *device) {
+        _cleanup_free_ char *sysname = NULL;
+        const char *sysnum;
+        const char *pos;
+        size_t len = 0;
+
+        pos = strrchr(device->devpath, '/');
+        if (!pos)
+                return -EINVAL;
+        pos ++;
+
+        /* devpath is not a root directory */
+        if (*pos == '\0' || pos <= device->devpath)
+                return -EINVAL;
+
+        sysname = strdup(pos);
+        if (!sysname)
+                return -ENOMEM;
+
+        /* some devices have '!' in their name, change that to '/' */
+        while (sysname[len] != '\0') {
+                if (sysname[len] == '!')
+                        sysname[len] = '/';
+
+                len ++;
+        }
+
+        /* trailing number */
+        while (len > 0 && isdigit(sysname[--len]))
+                sysnum = &sysname[len];
+
+        if (len == 0)
+                sysnum = NULL;
+
+        free(device->sysname);
+        device->sysname = sysname;
+        sysname = NULL;
+
+        device->sysnum = sysnum;
+
+        device->sysname_set = true;
+
+        return 0;
+}
+
+_public_ int sd_device_get_sysname(sd_device *device, const char **ret) {
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(ret, -EINVAL);
+
+        if (!device->sysname_set) {
+                r = device_set_sysname(device);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = device->sysname;
+
+        return 0;
+}
+
+_public_ int sd_device_get_sysnum(sd_device *device, const char **ret) {
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(ret, -EINVAL);
+
+        if (!device->sysname_set) {
+                r = device_set_sysname(device);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = device->sysnum;
+
+        return 0;
+}
+
+static bool is_valid_tag(const char *tag) {
+        assert(tag);
+
+        return !strchr(tag, ':') && !strchr(tag, ' ');
+}
+
+int device_add_tag(sd_device *device, const char *tag) {
+        int r;
+
+        assert(device);
+        assert(tag);
+
+        if (!is_valid_tag(tag))
+                return -EINVAL;
+
+        r = set_ensure_allocated(&device->tags, &string_hash_ops);
+        if (r < 0)
+                return r;
+
+        r = set_put_strdup(device->tags, tag);
+        if (r < 0)
+                return r;
+
+        device->tags_generation ++;
+        device->property_tags_outdated = true;
+
+        return 0;
+}
+
+int device_add_devlink(sd_device *device, const char *devlink) {
+        int r;
+
+        assert(device);
+        assert(devlink);
+
+        r = set_ensure_allocated(&device->devlinks, &string_hash_ops);
+        if (r < 0)
+                return r;
+
+        r = set_put_strdup(device->devlinks, devlink);
+        if (r < 0)
+                return r;
+
+        device->devlinks_generation ++;
+        device->property_devlinks_outdated = true;
+
+        return 0;
+}
+
+static int device_add_property_internal_from_string(sd_device *device, const char *str) {
+        _cleanup_free_ char *key = NULL;
+        char *value;
+
+        assert(device);
+        assert(str);
+
+        key = strdup(str);
+        if (!key)
+                return -ENOMEM;
+
+        value = strchr(key, '=');
+        if (!value)
+                return -EINVAL;
+
+        *value = '\0';
+
+        if (isempty(++value))
+                value = NULL;
+
+        return device_add_property_internal(device, key, value);
+}
+
+int device_set_usec_initialized(sd_device *device, const char *initialized) {
+        uint64_t usec_initialized;
+        int r;
+
+        assert(device);
+        assert(initialized);
+
+        r = safe_atou64(initialized, &usec_initialized);
+        if (r < 0)
+                return r;
+
+        r = device_add_property_internal(device, "USEC_INITIALIZED", initialized);
+        if (r < 0)
+                return r;
+
+        device->usec_initialized = usec_initialized;
+
+        return 0;
+}
+
+static int handle_db_line(sd_device *device, char key, const char *value) {
+        char *path;
+        int r;
+
+        assert(device);
+        assert(value);
+
+        switch (key) {
+        case 'G':
+                r = device_add_tag(device, value);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'S':
+                path = strjoina("/dev/", value);
+                r = device_add_devlink(device, path);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'E':
+                r = device_add_property_internal_from_string(device, value);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'I':
+                r = device_set_usec_initialized(device, value);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'L':
+                r = safe_atoi(value, &device->devlink_priority);
+                if (r < 0)
+                        return r;
+
+                break;
+        case 'W':
+                r = safe_atoi(value, &device->watch_handle);
+                if (r < 0)
+                        return r;
+
+                break;
+        default:
+                log_debug("device db: unknown key '%c'", key);
+        }
+
+        return 0;
+}
+
+int device_get_id_filename(sd_device *device, const char **ret) {
+        assert(device);
+        assert(ret);
+
+        if (!device->id_filename) {
+                _cleanup_free_ char *id = NULL;
+                const char *subsystem;
+                dev_t devnum;
+                int ifindex, r;
+
+                r = sd_device_get_subsystem(device, &subsystem);
+                if (r < 0)
+                        return r;
+
+                r = sd_device_get_devnum(device, &devnum);
+                if (r < 0)
+                        return r;
+
+                r = sd_device_get_ifindex(device, &ifindex);
+                if (r < 0)
+                        return r;
+
+                if (major(devnum) > 0) {
+                        /* use dev_t -- b259:131072, c254:0 */
+                        r = asprintf(&id, "%c%u:%u",
+                                     streq(subsystem, "block") ? 'b' : 'c',
+                                     major(devnum), minor(devnum));
+                        if (r < 0)
+                                return -errno;
+                } else if (ifindex > 0) {
+                        /* use netdev ifindex -- n3 */
+                        r = asprintf(&id, "n%u", ifindex);
+                        if (r < 0)
+                                return -errno;
+                } else {
+                        /* use $subsys:$sysname -- pci:0000:00:1f.2
+                         * sysname() has '!' translated, get it from devpath
+                         */
+                        const char *sysname;
+
+                        sysname = basename(device->devpath);
+                        if (!sysname)
+                                return -EINVAL;
+
+                        r = asprintf(&id, "+%s:%s", subsystem, sysname);
+                        if (r < 0)
+                                return -errno;
+                }
+
+                device->id_filename = id;
+                id = NULL;
+        }
+
+        *ret = device->id_filename;
+
+        return 0;
+}
+
+static int device_read_db(sd_device *device) {
+        _cleanup_free_ char *db = NULL;
+        char *path;
+        const char *id, *value;
+        char key;
+        size_t db_len;
+        unsigned i;
+        int r;
+
+        enum {
+                PRE_KEY,
+                KEY,
+                PRE_VALUE,
+                VALUE,
+                INVALID_LINE,
+        } state = PRE_KEY;
+
+        if (device->db_loaded || device->sealed)
+                return 0;
+
+        r = device_get_id_filename(device, &id);
+        if (r < 0)
+                return r;
+
+        path = strjoina("/run/udev/data/", id);
+
+        r = read_full_file(path, &db, &db_len);
+        if (r < 0) {
+                if (r == -ENOENT)
+                        return 0;
+                else {
+                        log_debug("sd-device: failed to read db '%s': %s", path, strerror(-r));
+                        return r;
+                }
+        }
+
+        /* devices with a database entry are initialized */
+        device->is_initialized = true;;
+
+        for (i = 0; i < db_len; i++) {
+                switch (state) {
+                case PRE_KEY:
+                        if (!strchr(NEWLINE, db[i])) {
+                                key = db[i];
+
+                                state = KEY;
+                        }
+
+                        break;
+                case KEY:
+                        if (db[i] != ':') {
+                                log_debug("sd-device: ignoring invalid db entry with key '%c'", key);
+
+                                state = INVALID_LINE;
+                        } else {
+                                db[i] = '\0';
+
+                                state = PRE_VALUE;
+                        }
+
+                        break;
+                case PRE_VALUE:
+                        value = &db[i];
+
+                        state = VALUE;
+
+                        break;
+                case INVALID_LINE:
+                        if (strchr(NEWLINE, db[i]))
+                                state = PRE_KEY;
+
+                        break;
+                case VALUE:
+                        if (strchr(NEWLINE, db[i])) {
+                                db[i] = '\0';
+                                r = handle_db_line(device, key, value);
+                                if (r < 0)
+                                        log_debug("sd-device: failed to handle db entry '%c:%s': %s", key, value, strerror(-r));
+
+                                state = PRE_KEY;
+                        }
+
+                        break;
+                default:
+                        assert_not_reached("invalid state when parsing db");
+                }
+        }
+
+        device->db_loaded = true;
+
+        return 0;
+}
+
+_public_ int sd_device_get_is_initialized(sd_device *device, int *initialized) {
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(initialized, -EINVAL);
+
+        r = device_read_db(device);
+        if (r < 0)
+                return r;
+
+        *initialized = device->is_initialized;
+
+        return 0;
+}
+
+_public_ int sd_device_get_usec_since_initialized(sd_device *device, uint64_t *usec) {
+        usec_t now_ts;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(usec, -EINVAL);
+
+        r = device_read_db(device);
+        if (r < 0)
+                return r;
+
+        if (!device->is_initialized)
+                return -EBUSY;
+
+        if (!device->usec_initialized)
+                return -ENODATA;
+
+        now_ts = now(clock_boottime_or_monotonic());
+
+        if (now_ts < device->usec_initialized)
+                return -EIO;
+
+        *usec = now_ts - device->usec_initialized;
+
+        return 0;
+}
+
+_public_ const char *sd_device_get_tag_first(sd_device *device) {
+        assert_return(device, NULL);
+
+        (void) device_read_db(device);
+
+        device->tags_iterator_generation = device->tags_generation;
+        device->tags_iterator = ITERATOR_FIRST;
+
+        return set_iterate(device->tags, &device->tags_iterator);
+}
+
+_public_ const char *sd_device_get_tag_next(sd_device *device) {
+        assert_return(device, NULL);
+
+        (void) device_read_db(device);
+
+        if (device->tags_iterator_generation != device->tags_generation)
+                return NULL;
+
+        return set_iterate(device->tags, &device->tags_iterator);
+}
+
+_public_ const char *sd_device_get_devlink_first(sd_device *device) {
+        assert_return(device, NULL);
+
+        (void) device_read_db(device);
+
+        device->devlinks_iterator_generation = device->devlinks_generation;
+        device->devlinks_iterator = ITERATOR_FIRST;
+
+        return set_iterate(device->devlinks, &device->devlinks_iterator);
+}
+
+_public_ const char *sd_device_get_devlink_next(sd_device *device) {
+        assert_return(device, NULL);
+
+        (void) device_read_db(device);
+
+        if (device->devlinks_iterator_generation != device->devlinks_generation)
+                return NULL;
+
+        return set_iterate(device->devlinks, &device->devlinks_iterator);
+}
+
+static int device_properties_prepare(sd_device *device) {
+        int r;
+
+        assert(device);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        r = device_read_db(device);
+        if (r < 0)
+                return r;
+
+        if (device->property_devlinks_outdated) {
+                char *devlinks = NULL;
+                const char *devlink;
+
+                devlink = sd_device_get_devlink_first(device);
+                if (devlink)
+                        devlinks = strdupa(devlink);
+
+                while ((devlink = sd_device_get_devlink_next(device)))
+                        devlinks = strjoina(devlinks, " ", devlink);
+
+                r = device_add_property_internal(device, "DEVLINKS", devlinks);
+                if (r < 0)
+                        return r;
+
+                device->property_devlinks_outdated = false;
+        }
+
+        if (device->property_tags_outdated) {
+                char *tags = NULL;
+                const char *tag;
+
+                tag = sd_device_get_tag_first(device);
+                if (tag)
+                        tags = strjoina(":", tag);
+
+                while ((tag = sd_device_get_tag_next(device)))
+                        tags = strjoina(tags, ":", tag);
+
+                tags = strjoina(tags, ":");
+
+                r = device_add_property_internal(device, "TAGS", tags);
+                if (r < 0)
+                        return r;
+
+                device->property_tags_outdated = false;
+        }
+
+        return 0;
+}
+
+_public_ const char *sd_device_get_property_first(sd_device *device, const char **_value) {
+        const char *key;
+        const char *value;
+        int r;
+
+        assert_return(device, NULL);
+
+        r = device_properties_prepare(device);
+        if (r < 0)
+                return NULL;
+
+        device->properties_iterator_generation = device->properties_generation;
+        device->properties_iterator = ITERATOR_FIRST;
+
+        value = ordered_hashmap_iterate(device->properties, &device->properties_iterator, (const void**)&key);
+
+        if (_value)
+                *_value = value;
+
+        return key;
+}
+
+_public_ const char *sd_device_get_property_next(sd_device *device, const char **_value) {
+        const char *key;
+        const char *value;
+        int r;
+
+        assert_return(device, NULL);
+
+        r = device_properties_prepare(device);
+        if (r < 0)
+                return NULL;
+
+        if (device->properties_iterator_generation != device->properties_generation)
+                return NULL;
+
+        value = ordered_hashmap_iterate(device->properties, &device->properties_iterator, (const void**)&key);
+
+        if (_value)
+                *_value = value;
+
+        return key;
+}
+
+static int device_sysattrs_read_all(sd_device *device) {
+        _cleanup_closedir_ DIR *dir = NULL;
+        const char *syspath;
+        struct dirent *dent;
+        int r;
+
+        assert(device);
+
+        if (device->sysattrs_read)
+                return 0;
+
+        r = sd_device_get_syspath(device, &syspath);
+        if (r < 0)
+                return r;
+
+        dir = opendir(syspath);
+        if (!dir)
+                return -errno;
+
+        r = set_ensure_allocated(&device->sysattrs, &string_hash_ops);
+        if (r < 0)
+                return r;
+
+        for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
+                char *path;
+                struct stat statbuf;
+
+                /* only handle symlinks and regular files */
+                if (dent->d_type != DT_LNK && dent->d_type != DT_REG)
+                        continue;
+
+                path = strjoina(syspath, "/", dent->d_name);
+
+                if (lstat(path, &statbuf) != 0)
+                        continue;
+
+                if (!(statbuf.st_mode & S_IRUSR))
+                        continue;
+
+                r = set_put_strdup(device->sysattrs, dent->d_name);
+                if (r < 0)
+                        return r;
+        }
+
+        device->sysattrs_read = true;
+
+        return 0;
+}
+
+_public_ const char *sd_device_get_sysattr_first(sd_device *device) {
+        int r;
+
+        assert_return(device, NULL);
+
+        if (!device->sysattrs_read) {
+                r = device_sysattrs_read_all(device);
+                if (r < 0) {
+                        errno = -r;
+                        return NULL;
+                }
+        }
+
+        device->sysattrs_iterator = ITERATOR_FIRST;
+
+        return set_iterate(device->sysattrs, &device->sysattrs_iterator);
+}
+
+_public_ const char *sd_device_get_sysattr_next(sd_device *device) {
+        assert_return(device, NULL);
+
+        if (!device->sysattrs_read)
+                return NULL;
+
+        return set_iterate(device->sysattrs, &device->sysattrs_iterator);
+}
+
+_public_ int sd_device_has_tag(sd_device *device, const char *tag) {
+        assert_return(device, -EINVAL);
+        assert_return(tag, -EINVAL);
+
+        (void) device_read_db(device);
+
+        return !!set_contains(device->tags, tag);
+}
+
+_public_ int sd_device_get_property_value(sd_device *device, const char *key, const char **_value) {
+        char *value;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(key, -EINVAL);
+        assert_return(_value, -EINVAL);
+
+        r = device_properties_prepare(device);
+        if (r < 0)
+                return r;
+
+        value = ordered_hashmap_get(device->properties, key);
+        if (!value)
+                return -ENOENT;
+
+        *_value = value;
+
+        return 0;
+}
+
+/* replaces the value if it already exists */
+static int device_add_sysattr_value(sd_device *device, const char *_key, const char *_value) {
+        _cleanup_free_ char *key = NULL;
+        _cleanup_free_ char *value = NULL;
+        int r;
+
+        assert(device);
+        assert(_key);
+
+        r = hashmap_ensure_allocated(&device->sysattr_values, &string_hash_ops);
+        if (r < 0)
+                return r;
+
+        value = hashmap_remove2(device->sysattr_values, _key, (void **)&key);
+        if (!key) {
+                key = strdup(_key);
+                if (!key)
+                        return -ENOMEM;
+        }
+
+        free(value);
+        value = NULL;
+
+        if (_value) {
+                value = strdup(_value);
+                if (!value)
+                        return -ENOMEM;
+        }
+
+        r = hashmap_put(device->sysattr_values, key, value);
+        if (r < 0)
+                return r;
+
+        key = NULL;
+        value = NULL;
+
+        return 0;
+}
+
+static int device_get_sysattr_value(sd_device *device, const char *_key, const char **_value) {
+        const char *key = NULL, *value;
+
+        assert(device);
+        assert(_key);
+
+        value = hashmap_get2(device->sysattr_values, _key, (void **) &key);
+        if (!key)
+                return -ENOENT;
+
+        if (_value)
+                *_value = value;
+
+        return 0;
+}
+
+/* We cache all sysattr lookups. If an attribute does not exist, it is stored
+ * with a NULL value in the cache, otherwise the returned string is stored */
+_public_ int sd_device_get_sysattr_value(sd_device *device, const char *sysattr, const char **_value) {
+        _cleanup_free_ char *value = NULL;
+        const char *syspath, *cached_value = NULL;
+        char *path;
+        struct stat statbuf;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(sysattr, -EINVAL);
+
+        /* look for possibly already cached result */
+        r = device_get_sysattr_value(device, sysattr, &cached_value);
+        if (r != -ENOENT) {
+                if (r < 0)
+                        return r;
+
+                if (!cached_value)
+                        /* we looked up the sysattr before and it did not exist */
+                        return -ENOENT;
+
+                if (_value)
+                        *_value = cached_value;
+
+                return 0;
+        }
+
+        r = sd_device_get_syspath(device, &syspath);
+        if (r < 0)
+                return r;
+
+        path = strjoina(syspath, "/", sysattr);
+        r = lstat(path, &statbuf);
+        if (r < 0) {
+                /* remember that we could not access the sysattr */
+                r = device_add_sysattr_value(device, sysattr, NULL);
+                if (r < 0)
+                        return r;
+
+                return -ENOENT;
+        } else if (S_ISLNK(statbuf.st_mode)) {
+                /* Some core links return only the last element of the target path,
+                 * these are just values, the paths should not be exposed. */
+                if (STR_IN_SET(sysattr, "driver", "subsystem", "module")) {
+                        r = readlink_value(path, &value);
+                        if (r < 0)
+                                return r;
+                } else
+                        return -EINVAL;
+        } else if (S_ISDIR(statbuf.st_mode)) {
+                /* skip directories */
+                return -EINVAL;
+        } else if (!(statbuf.st_mode & S_IRUSR)) {
+                /* skip non-readable files */
+                return -EPERM;
+        } else {
+                size_t size;
+
+                /* read attribute value */
+                r = read_full_file(path, &value, &size);
+                if (r < 0)
+                        return r;
+
+                /* drop trailing newlines */
+                while (size > 0 && value[--size] == '\n')
+                        value[size] = '\0';
+        }
+
+        r = device_add_sysattr_value(device, sysattr, value);
+        if (r < 0)
+                return r;
+
+        *_value = value;
+        value = NULL;
+
+        return 0;
+}
+
+static void device_remove_sysattr_value(sd_device *device, const char *_key) {
+        _cleanup_free_ char *key = NULL;
+        _cleanup_free_ char *value = NULL;
+
+        assert(device);
+        assert(_key);
+
+        value = hashmap_remove2(device->sysattr_values, _key, (void **) &key);
+
+        return;
+}
+
+/* set the attribute and save it in the cache. If a NULL value is passed the
+ * attribute is cleared from the cache */
+_public_ int sd_device_set_sysattr_value(sd_device *device, const char *sysattr, char *value) {
+        _cleanup_close_ int fd = -1;
+        const char *syspath;
+        char *path;
+        struct stat statbuf;
+        size_t value_len = 0;
+        ssize_t size;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(sysattr, -EINVAL);
+
+        if (!value) {
+                device_remove_sysattr_value(device, sysattr);
+
+                return 0;
+        }
+
+        r = sd_device_get_syspath(device, &syspath);
+        if (r < 0)
+                return r;
+
+        path = strjoina(syspath, "/", sysattr);
+        r = lstat(path, &statbuf);
+        if (r < 0) {
+                r = device_add_sysattr_value(device, sysattr, "");
+                if (r < 0)
+                        return r;
+
+                return -ENXIO;
+        }
+
+        if (S_ISLNK(statbuf.st_mode))
+                return -EINVAL;
+
+        /* skip directories */
+        if (S_ISDIR(statbuf.st_mode))
+                return -EISDIR;
+
+        /* skip non-readable files */
+        if ((statbuf.st_mode & S_IRUSR) == 0)
+                return -EACCES;
+
+        value_len = strlen(value);
+
+        /* drop trailing newlines */
+        while (value_len > 0 && value[--value_len] == '\n')
+                value[value_len] = '\0';
+
+        /* value length is limited to 4k */
+        if (value_len > 4096)
+                return -EINVAL;
+
+        fd = open(path, O_WRONLY | O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        size = write(fd, value, value_len);
+        if (size < 0)
+                return -errno;
+
+        if ((size_t)size != value_len)
+                return -EIO;
+
+        r = device_add_sysattr_value(device, sysattr, value);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
diff --git a/src/systemd/sd-device.h b/src/systemd/sd-device.h
new file mode 100644
index 0000000000..d737753f70
--- /dev/null
+++ b/src/systemd/sd-device.h
@@ -0,0 +1,77 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef foosddevicehfoo
+#define foosddevicehfoo
+
+/***
+  This file is part of systemd.
+
+  Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
+  Copyright 2014 Tom Gundersen <teg@jklm.no>
+
+  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.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/types.h>
+#include <stdint.h>
+
+#include "_sd-common.h"
+
+_SD_BEGIN_DECLARATIONS;
+
+typedef struct sd_device sd_device;
+
+sd_device *sd_device_ref(sd_device *device);
+sd_device *sd_device_unref(sd_device *device);
+
+int sd_device_new_from_syspath(sd_device **ret, const char *syspath);
+int sd_device_new_from_devnum(sd_device **ret, char type, dev_t devnum);
+int sd_device_new_from_subsystem_sysname(sd_device **ret, const char *subsystem, const char *sysname);
+int sd_device_new_from_device_id(sd_device **ret, const char *id);
+
+int sd_device_get_parent(sd_device *child, sd_device **ret);
+int sd_device_get_parent_with_subsystem_devtype(sd_device *child, const char *subsystem, const char *devtype, sd_device **ret);
+
+int sd_device_get_syspath(sd_device *device, const char **ret);
+int sd_device_get_subsystem(sd_device *device, const char **ret);
+int sd_device_get_devtype(sd_device *device, const char **ret);
+int sd_device_get_devnum(sd_device *device, dev_t *devnum);
+int sd_device_get_ifindex(sd_device *device, int *ifindex);
+int sd_device_get_driver(sd_device *device, const char **ret);
+int sd_device_get_devpath(sd_device *device, const char **ret);
+int sd_device_get_devname(sd_device *device, const char **ret);
+int sd_device_get_sysname(sd_device *device, const char **ret);
+int sd_device_get_sysnum(sd_device *device, const char **ret);
+
+int sd_device_get_is_initialized(sd_device *device, int *initialized);
+int sd_device_get_usec_since_initialized(sd_device *device, uint64_t *usec);
+
+const char *sd_device_get_tag_first(sd_device *device);
+const char *sd_device_get_tag_next(sd_device *device);
+const char *sd_device_get_devlink_first(sd_device *device);
+const char *sd_device_get_devlink_next(sd_device *device);
+const char *sd_device_get_property_first(sd_device *device, const char **value);
+const char *sd_device_get_property_next(sd_device *device, const char **value);
+const char *sd_device_get_sysattr_first(sd_device *device);
+const char *sd_device_get_sysattr_next(sd_device *device);
+
+int sd_device_has_tag(sd_device *device, const char *tag);
+int sd_device_get_property_value(sd_device *device, const char *key, const char **value);
+int sd_device_get_sysattr_value(sd_device *device, const char *sysattr, const char **_value);
+
+int sd_device_set_sysattr_value(sd_device *device, const char *sysattr, char *value);
+
+_SD_END_DECLARATIONS;
+
+#endif