Adding upstream version 255.4.upstream/255.4

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

1 files changed, 2715 insertions, 0 deletions

diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
new file mode 100644
index 0000000..2fbc619
--- /dev/null
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -0,0 +1,2715 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <ctype.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+
+#include "sd-device.h"
+
+#include "alloc-util.h"
+#include "chase.h"
+#include "device-internal.h"
+#include "device-private.h"
+#include "device-util.h"
+#include "devnum-util.h"
+#include "dirent-util.h"
+#include "env-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "format-util.h"
+#include "fs-util.h"
+#include "hashmap.h"
+#include "id128-util.h"
+#include "macro.h"
+#include "missing_magic.h"
+#include "netlink-util.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "set.h"
+#include "socket-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "strxcpyx.h"
+#include "user-util.h"
+
+int device_new_aux(sd_device **ret) {
+        sd_device *device;
+
+        assert(ret);
+
+        device = new(sd_device, 1);
+        if (!device)
+                return -ENOMEM;
+
+        *device = (sd_device) {
+                .n_ref = 1,
+                .devmode = MODE_INVALID,
+                .devuid = UID_INVALID,
+                .devgid = GID_INVALID,
+                .action = _SD_DEVICE_ACTION_INVALID,
+        };
+
+        *ret = device;
+        return 0;
+}
+
+static sd_device *device_free(sd_device *device) {
+        assert(device);
+
+        sd_device_unref(device->parent);
+        free(device->syspath);
+        free(device->sysname);
+        free(device->devtype);
+        free(device->devname);
+        free(device->subsystem);
+        free(device->driver_subsystem);
+        free(device->driver);
+        free(device->device_id);
+        free(device->properties_strv);
+        free(device->properties_nulstr);
+
+        ordered_hashmap_free(device->properties);
+        ordered_hashmap_free(device->properties_db);
+        hashmap_free(device->sysattr_values);
+        set_free(device->sysattrs);
+        set_free(device->all_tags);
+        set_free(device->current_tags);
+        set_free(device->devlinks);
+        hashmap_free(device->children);
+
+        return mfree(device);
+}
+
+DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_device, sd_device, device_free);
+
+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) {
+                _unused_ _cleanup_free_ char *old_value = NULL;
+                _cleanup_free_ char *new_key = NULL, *new_value = NULL, *old_key = NULL;
+                int r;
+
+                r = ordered_hashmap_ensure_allocated(properties, &string_hash_ops_free_free);
+                if (r < 0)
+                        return r;
+
+                new_key = strdup(key);
+                if (!new_key)
+                        return -ENOMEM;
+
+                new_value = strdup(value);
+                if (!new_value)
+                        return -ENOMEM;
+
+                old_value = ordered_hashmap_get2(*properties, key, (void**) &old_key);
+
+                /* ordered_hashmap_replace() does not fail when the hashmap already has the entry. */
+                r = ordered_hashmap_replace(*properties, new_key, new_value);
+                if (r < 0)
+                        return r;
+
+                TAKE_PTR(new_key);
+                TAKE_PTR(new_value);
+        } else {
+                _unused_ _cleanup_free_ char *old_value = NULL;
+                _cleanup_free_ char *old_key = NULL;
+
+                old_value = ordered_hashmap_remove2(*properties, key, (void**) &old_key);
+        }
+
+        if (!db) {
+                device->properties_generation++;
+                device->properties_buf_outdated = true;
+        }
+
+        return 0;
+}
+
+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);
+
+        if (verify) {
+                _cleanup_close_ int fd = -EBADF;
+
+                /* The input path maybe a symlink located outside of /sys. Let's try to chase the symlink at first.
+                 * The primary use case is that e.g. /proc/device-tree is a symlink to /sys/firmware/devicetree/base.
+                 * By chasing symlinks in the path at first, we can call sd_device_new_from_path() with such path. */
+                r = chase(_syspath, NULL, 0, &syspath, &fd);
+                if (r == -ENOENT)
+                         /* the device does not exist (any more?) */
+                        return log_debug_errno(SYNTHETIC_ERRNO(ENODEV),
+                                               "sd-device: Failed to chase symlinks in \"%s\".", _syspath);
+                if (r < 0)
+                        return log_debug_errno(r, "sd-device: Failed to get target of '%s': %m", _syspath);
+
+                if (!path_startswith(syspath, "/sys")) {
+                        _cleanup_free_ char *real_sys = NULL, *new_syspath = NULL;
+                        char *p;
+
+                        /* /sys is a symlink to somewhere sysfs is mounted on? In that case, we convert the path to real sysfs to "/sys". */
+                        r = chase("/sys", NULL, 0, &real_sys, NULL);
+                        if (r < 0)
+                                return log_debug_errno(r, "sd-device: Failed to chase symlink /sys: %m");
+
+                        p = path_startswith(syspath, real_sys);
+                        if (!p)
+                                return log_debug_errno(SYNTHETIC_ERRNO(ENODEV),
+                                                       "sd-device: Canonicalized path '%s' does not starts with sysfs mount point '%s'",
+                                                       syspath, real_sys);
+
+                        new_syspath = path_join("/sys", p);
+                        if (!new_syspath)
+                                return log_oom_debug();
+
+                        free_and_replace(syspath, new_syspath);
+                        path_simplify(syspath);
+                }
+
+                if (path_startswith(syspath, "/sys/devices/")) {
+                        /* For proper devices, stricter rules apply: they must have a 'uevent' file,
+                         * otherwise we won't allow them */
+
+                        if (faccessat(fd, "uevent", F_OK, 0) < 0) {
+                                if (errno == ENOENT)
+                                        /* This is not a valid device.  Note, this condition is quite often
+                                         * satisfied when enumerating devices or finding a parent device.
+                                         * Hence, use log_trace_errno() here. */
+                                        return log_trace_errno(SYNTHETIC_ERRNO(ENODEV),
+                                                               "sd-device: the uevent file \"%s/uevent\" does not exist.", syspath);
+                                if (errno == ENOTDIR)
+                                        /* Not actually a directory. */
+                                        return log_debug_errno(SYNTHETIC_ERRNO(ENODEV),
+                                                               "sd-device: the syspath \"%s\" is not a directory.", syspath);
+
+                                return log_debug_errno(errno, "sd-device: cannot find uevent file for %s: %m", syspath);
+                        }
+                } else {
+                        struct stat st;
+
+                        /* For everything else lax rules apply: they just need to be a directory */
+
+                        if (fstat(fd, &st) < 0)
+                                return log_debug_errno(errno, "sd-device: failed to check if syspath \"%s\" is a directory: %m", syspath);
+                        if (!S_ISDIR(st.st_mode))
+                                return log_debug_errno(SYNTHETIC_ERRNO(ENODEV),
+                                                       "sd-device: the syspath \"%s\" is not a directory.", syspath);
+                }
+
+                /* Only operate on sysfs, i.e. refuse going down into /sys/fs/cgroup/ or similar places where
+                 * things are not arranged as kobjects in kernel, and hence don't necessarily have
+                 * kobject/attribute structure. */
+                r = getenv_bool_secure("SYSTEMD_DEVICE_VERIFY_SYSFS");
+                if (r < 0 && r != -ENXIO)
+                        log_debug_errno(r, "Failed to parse $SYSTEMD_DEVICE_VERIFY_SYSFS value: %m");
+                if (r != 0) {
+                        r = fd_is_fs_type(fd, SYSFS_MAGIC);
+                        if (r < 0)
+                                return log_debug_errno(r, "sd-device: failed to check if syspath \"%s\" is backed by sysfs.", syspath);
+                        if (r == 0)
+                                return log_debug_errno(SYNTHETIC_ERRNO(ENODEV),
+                                                       "sd-device: the syspath \"%s\" is outside of sysfs, refusing.", syspath);
+                }
+        } else {
+                /* must be a subdirectory of /sys */
+                if (!path_startswith(_syspath, "/sys/"))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "sd-device: Syspath '%s' is not a subdirectory of /sys",
+                                               _syspath);
+
+                r = path_simplify_alloc(_syspath, &syspath);
+                if (r < 0)
+                        return r;
+        }
+
+        assert_se(devpath = startswith(syspath, "/sys"));
+        if (devpath[0] != '/')
+                return log_debug_errno(SYNTHETIC_ERRNO(ENODEV), "sd-device: \"/sys\" alone is not a valid device path.");
+
+        r = device_add_property_internal(device, "DEVPATH", devpath);
+        if (r < 0)
+                return log_debug_errno(r, "sd-device: Failed to add \"DEVPATH\" property for device \"%s\": %m", syspath);
+
+        free_and_replace(device->syspath, syspath);
+        device->devpath = devpath;
+
+        /* Unset sysname and sysnum, they will be assigned when requested. */
+        device->sysnum = NULL;
+        device->sysname = mfree(device->sysname);
+        return 0;
+}
+
+static int device_new_from_syspath(sd_device **ret, const char *syspath, bool strict) {
+        _cleanup_(sd_device_unrefp) sd_device *device = NULL;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(syspath, -EINVAL);
+
+        if (strict && !path_startswith(syspath, "/sys/"))
+                return -EINVAL;
+
+        r = device_new_aux(&device);
+        if (r < 0)
+                return r;
+
+        r = device_set_syspath(device, syspath, /* verify= */ true);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(device);
+        return 0;
+}
+
+_public_ int sd_device_new_from_syspath(sd_device **ret, const char *syspath) {
+        return device_new_from_syspath(ret, syspath, /* strict = */ true);
+}
+
+int device_new_from_mode_and_devnum(sd_device **ret, mode_t mode, dev_t devnum) {
+        _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
+        _cleanup_free_ char *syspath = NULL;
+        const char *t, *subsystem = NULL;
+        dev_t n;
+        int r;
+
+        assert(ret);
+
+        if (S_ISCHR(mode))
+                t = "char";
+        else if (S_ISBLK(mode))
+                t = "block";
+        else
+                return -ENOTTY;
+
+        if (major(devnum) == 0)
+                return -ENODEV;
+
+        if (asprintf(&syspath, "/sys/dev/%s/" DEVNUM_FORMAT_STR, t, DEVNUM_FORMAT_VAL(devnum)) < 0)
+                return -ENOMEM;
+
+        r = sd_device_new_from_syspath(&dev, syspath);
+        if (r < 0)
+                return r;
+
+        r = sd_device_get_devnum(dev, &n);
+        if (r == -ENOENT)
+                return -ENXIO;
+        if (r < 0)
+                return r;
+        if (n != devnum)
+                return -ENXIO;
+
+        r = sd_device_get_subsystem(dev, &subsystem);
+        if (r < 0 && r != -ENOENT)
+                return r;
+        if (streq_ptr(subsystem, "block") != !!S_ISBLK(mode))
+                return -ENXIO;
+
+        *ret = TAKE_PTR(dev);
+        return 0;
+}
+
+_public_ int sd_device_new_from_devnum(sd_device **ret, char type, dev_t devnum) {
+        assert_return(ret, -EINVAL);
+        assert_return(IN_SET(type, 'b', 'c'), -EINVAL);
+
+        return device_new_from_mode_and_devnum(ret, type == 'b' ? S_IFBLK : S_IFCHR, devnum);
+}
+
+static int device_new_from_main_ifname(sd_device **ret, const char *ifname) {
+        const char *syspath;
+
+        assert(ret);
+        assert(ifname);
+
+        syspath = strjoina("/sys/class/net/", ifname);
+        return sd_device_new_from_syspath(ret, syspath);
+}
+
+_public_ int sd_device_new_from_ifname(sd_device **ret, const char *ifname) {
+        _cleanup_free_ char *main_name = NULL;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(ifname, -EINVAL);
+
+        r = parse_ifindex(ifname);
+        if (r > 0)
+                return sd_device_new_from_ifindex(ret, r);
+
+        if (ifname_valid(ifname)) {
+                r = device_new_from_main_ifname(ret, ifname);
+                if (r >= 0)
+                        return r;
+        }
+
+        r = rtnl_resolve_link_alternative_name(NULL, ifname, &main_name);
+        if (r < 0)
+                return r;
+
+        return device_new_from_main_ifname(ret, main_name);
+}
+
+_public_ int sd_device_new_from_ifindex(sd_device **ret, int ifindex) {
+        _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
+        char ifname[IF_NAMESIZE];
+        int r, i;
+
+        assert_return(ret, -EINVAL);
+        assert_return(ifindex > 0, -EINVAL);
+
+        if (format_ifname(ifindex, ifname) < 0)
+                return -ENODEV;
+
+        r = device_new_from_main_ifname(&dev, ifname);
+        if (r < 0)
+                return r;
+
+        r = sd_device_get_ifindex(dev, &i);
+        if (r == -ENOENT)
+                return -ENXIO;
+        if (r < 0)
+                return r;
+        if (i != ifindex)
+                return -ENXIO;
+
+        *ret = TAKE_PTR(dev);
+        return 0;
+}
+
+static int device_strjoin_new(
+                const char *a,
+                const char *b,
+                const char *c,
+                const char *d,
+                sd_device **ret) {
+
+        const char *p;
+        int r;
+
+        p = strjoina(a, b, c, d);
+        if (access(p, F_OK) < 0)
+                return IN_SET(errno, ENOENT, ENAMETOOLONG) ? 0 : -errno; /* If this sysfs is too long then it doesn't exist either */
+
+        r = sd_device_new_from_syspath(ret, p);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+_public_ int sd_device_new_from_subsystem_sysname(
+                sd_device **ret,
+                const char *subsystem,
+                const char *sysname) {
+
+        char *name;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(subsystem, -EINVAL);
+        assert_return(sysname, -EINVAL);
+
+        if (!path_is_normalized(subsystem))
+                return -EINVAL;
+        if (!path_is_normalized(sysname))
+                return -EINVAL;
+
+        /* translate sysname back to sysfs filename */
+        name = strdupa_safe(sysname);
+        string_replace_char(name, '/', '!');
+
+        if (streq(subsystem, "subsystem")) {
+                FOREACH_STRING(s, "/sys/bus/", "/sys/class/") {
+                        r = device_strjoin_new(s, name, NULL, NULL, ret);
+                        if (r < 0)
+                                return r;
+                        if (r > 0)
+                                return 0;
+                }
+
+        } else if (streq(subsystem, "module")) {
+                r = device_strjoin_new("/sys/module/", name, NULL, NULL, ret);
+                if (r < 0)
+                        return r;
+                if (r > 0)
+                        return 0;
+
+        } else if (streq(subsystem, "drivers")) {
+                const char *sep;
+
+                sep = strchr(name, ':');
+                if (sep && sep[1] != '\0') { /* Require ":" and something non-empty after that. */
+
+                        const char *subsys = memdupa_suffix0(name, sep - name);
+                        sep++;
+
+                        if (streq(sep, "drivers")) /* If the sysname is "drivers", then it's the drivers directory itself that is meant. */
+                                r = device_strjoin_new("/sys/bus/", subsys, "/drivers", NULL, ret);
+                        else
+                                r = device_strjoin_new("/sys/bus/", subsys, "/drivers/", sep, ret);
+                        if (r < 0)
+                                return r;
+                        if (r > 0)
+                                return 0;
+                }
+        }
+
+        r = device_strjoin_new("/sys/bus/", subsystem, "/devices/", name, ret);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                return 0;
+
+        r = device_strjoin_new("/sys/class/", subsystem, "/", name, ret);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                return 0;
+
+        r = device_strjoin_new("/sys/firmware/", subsystem, "/", name, ret);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                return 0;
+
+        return -ENODEV;
+}
+
+_public_ int sd_device_new_from_stat_rdev(sd_device **ret, const struct stat *st) {
+        assert_return(ret, -EINVAL);
+        assert_return(st, -EINVAL);
+
+        return device_new_from_mode_and_devnum(ret, st->st_mode, st->st_rdev);
+}
+
+_public_ int sd_device_new_from_devname(sd_device **ret, const char *devname) {
+        struct stat st;
+        dev_t devnum;
+        mode_t mode;
+
+        assert_return(ret, -EINVAL);
+        assert_return(devname, -EINVAL);
+
+        /* This function actually accepts both devlinks and devnames, i.e. both symlinks and device
+         * nodes below /dev/. */
+
+        /* Also ignore when the specified path is "/dev". */
+        if (isempty(path_startswith(devname, "/dev")))
+                return -EINVAL;
+
+        if (device_path_parse_major_minor(devname, &mode, &devnum) >= 0)
+                /* Let's shortcut when "/dev/block/maj:min" or "/dev/char/maj:min" is specified.
+                 * In that case, we can directly convert the path to syspath, hence it is not necessary
+                 * that the specified path exists. So, this works fine without udevd being running. */
+                return device_new_from_mode_and_devnum(ret, mode, devnum);
+
+        if (stat(devname, &st) < 0)
+                return ERRNO_IS_DEVICE_ABSENT(errno) ? -ENODEV : -errno;
+
+        return sd_device_new_from_stat_rdev(ret, &st);
+}
+
+_public_ int sd_device_new_from_path(sd_device **ret, const char *path) {
+        assert_return(ret, -EINVAL);
+        assert_return(path, -EINVAL);
+
+        if (path_startswith(path, "/dev"))
+                return sd_device_new_from_devname(ret, path);
+
+        return device_new_from_syspath(ret, path, /* strict = */ false);
+}
+
+int device_set_devtype(sd_device *device, const char *devtype) {
+        _cleanup_free_ char *t = NULL;
+        int r;
+
+        assert(device);
+        assert(devtype);
+
+        t = strdup(devtype);
+        if (!t)
+                return -ENOMEM;
+
+        r = device_add_property_internal(device, "DEVTYPE", t);
+        if (r < 0)
+                return r;
+
+        return free_and_replace(device->devtype, t);
+}
+
+int device_set_ifindex(sd_device *device, const char *name) {
+        int r, ifindex;
+
+        assert(device);
+        assert(name);
+
+        ifindex = parse_ifindex(name);
+        if (ifindex < 0)
+                return ifindex;
+
+        r = device_add_property_internal(device, "IFINDEX", name);
+        if (r < 0)
+                return r;
+
+        device->ifindex = ifindex;
+
+        return 0;
+}
+
+static int mangle_devname(const char *p, char **ret) {
+        char *q;
+
+        assert(p);
+        assert(ret);
+
+        if (!path_is_safe(p))
+                return -EINVAL;
+
+        /* When the path is absolute, it must start with "/dev/", but ignore "/dev/" itself. */
+        if (path_is_absolute(p)) {
+                if (isempty(path_startswith(p, "/dev/")))
+                        return -EINVAL;
+
+                q = strdup(p);
+        } else
+                q = path_join("/dev/", p);
+        if (!q)
+                return -ENOMEM;
+
+        path_simplify(q);
+
+        *ret = q;
+        return 0;
+}
+
+int device_set_devname(sd_device *device, const char *devname) {
+        _cleanup_free_ char *t = NULL;
+        int r;
+
+        assert(device);
+        assert(devname);
+
+        r = mangle_devname(devname, &t);
+        if (r < 0)
+                return r;
+
+        r = device_add_property_internal(device, "DEVNAME", t);
+        if (r < 0)
+                return r;
+
+        return free_and_replace(device->devname, t);
+}
+
+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, min = 0;
+        int r;
+
+        assert(device);
+        assert(major);
+
+        r = safe_atou(major, &maj);
+        if (r < 0)
+                return r;
+        if (maj == 0)
+                return 0;
+        if (!DEVICE_MAJOR_VALID(maj))
+                return -EINVAL;
+
+        if (minor) {
+                r = safe_atou(minor, &min);
+                if (r < 0)
+                        return r;
+                if (!DEVICE_MINOR_VALID(min))
+                        return -EINVAL;
+        }
+
+        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;
+}
+
+int device_set_diskseq(sd_device *device, const char *str) {
+        uint64_t diskseq;
+        int r;
+
+        assert(device);
+        assert(str);
+
+        r = safe_atou64(str, &diskseq);
+        if (r < 0)
+                return r;
+        if (diskseq == 0)
+                return -EINVAL;
+
+        r = device_add_property_internal(device, "DISKSEQ", str);
+        if (r < 0)
+                return r;
+
+        device->diskseq = diskseq;
+
+        return 0;
+}
+
+static int handle_uevent_line(
+                sd_device *device,
+                const char *key,
+                const char *value,
+                const char **major,
+                const char **minor) {
+
+        assert(device);
+        assert(key);
+        assert(value);
+        assert(major);
+        assert(minor);
+
+        if (streq(key, "DEVTYPE"))
+                return device_set_devtype(device, value);
+        if (streq(key, "IFINDEX"))
+                return device_set_ifindex(device, value);
+        if (streq(key, "DEVNAME"))
+                return device_set_devname(device, value);
+        if (streq(key, "DEVMODE"))
+                return device_set_devmode(device, value);
+        if (streq(key, "DISKSEQ"))
+                return device_set_diskseq(device, value);
+        if (streq(key, "MAJOR"))
+                *major = value;
+        else if (streq(key, "MINOR"))
+                *minor = value;
+        else
+                return device_add_property_internal(device, key, value);
+
+        return 0;
+}
+
+int device_read_uevent_file(sd_device *device) {
+        _cleanup_free_ char *uevent = NULL;
+        const char *syspath, *key = NULL, *value = NULL, *major = NULL, *minor = NULL;
+        char *path;
+        size_t uevent_len;
+        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;
+
+        device->uevent_loaded = true;
+
+        path = strjoina(syspath, "/uevent");
+
+        r = read_full_virtual_file(path, &uevent, &uevent_len);
+        if (r == -EACCES || ERRNO_IS_NEG_DEVICE_ABSENT(r))
+                /* The uevent files may be write-only, the device may be already removed, or the device
+                 * may not have the uevent file. */
+                return 0;
+        if (r < 0)
+                return log_device_debug_errno(device, r, "sd-device: Failed to read uevent file '%s': %m", path);
+
+        for (size_t 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_device_debug(device, "sd-device: Invalid uevent line '%s', ignoring", key);
+
+                                state = PRE_KEY;
+                        }
+
+                        break;
+                case PRE_VALUE:
+                        value = &uevent[i];
+                        state = VALUE;
+
+                        _fallthrough_; /* to handle empty property */
+                case VALUE:
+                        if (strchr(NEWLINE, uevent[i])) {
+                                uevent[i] = '\0';
+
+                                r = handle_uevent_line(device, key, value, &major, &minor);
+                                if (r < 0)
+                                        log_device_debug_errno(device, r, "sd-device: Failed to handle uevent entry '%s=%s', ignoring: %m", key, value);
+
+                                state = PRE_KEY;
+                        }
+
+                        break;
+                default:
+                        assert_not_reached();
+                }
+
+        if (major) {
+                r = device_set_devnum(device, major, minor);
+                if (r < 0)
+                        log_device_debug_errno(device, r, "sd-device: Failed to set 'MAJOR=%s' or 'MINOR=%s' from '%s', ignoring: %m", major, strna(minor), path);
+        }
+
+        return 0;
+}
+
+_public_ int sd_device_get_ifindex(sd_device *device, int *ifindex) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        if (device->ifindex <= 0)
+                return -ENOENT;
+
+        if (ifindex)
+                *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': {
+                dev_t devt;
+
+                if (isempty(id))
+                        return -EINVAL;
+
+                r = parse_devnum(id + 1, &devt);
+                if (r < 0)
+                        return r;
+
+                return sd_device_new_from_devnum(ret, id[0], devt);
+        }
+
+        case 'n': {
+                int ifindex;
+
+                ifindex = parse_ifindex(id + 1);
+                if (ifindex < 0)
+                        return ifindex;
+
+                return sd_device_new_from_ifindex(ret, ifindex);
+        }
+
+        case '+': {
+                const char *subsys, *sep;
+
+                sep = strchr(id + 1, ':');
+                if (!sep || sep - id - 1 > NAME_MAX)
+                        return -EINVAL;
+
+                subsys = memdupa_suffix0(id + 1, sep - id - 1);
+
+                return sd_device_new_from_subsystem_sysname(ret, subsys, sep + 1);
+        }
+
+        default:
+                return -EINVAL;
+        }
+}
+
+_public_ int sd_device_get_syspath(sd_device *device, const char **ret) {
+        assert_return(device, -EINVAL);
+
+        assert(path_startswith(device->syspath, "/sys/"));
+
+        if (ret)
+                *ret = device->syspath;
+
+        return 0;
+}
+
+DEFINE_PRIVATE_HASH_OPS_FULL(
+        device_by_path_hash_ops,
+        char, path_hash_func, path_compare, free,
+        sd_device, sd_device_unref);
+
+static int device_enumerate_children_internal(sd_device *device, const char *subdir, Set **stack, Hashmap **children) {
+        _cleanup_closedir_ DIR *dir = NULL;
+        int r;
+
+        assert(device);
+        assert(stack);
+        assert(children);
+
+        r = device_opendir(device, subdir, &dir);
+        if (r < 0)
+                return r;
+
+        FOREACH_DIRENT_ALL(de, dir, return -errno) {
+                _cleanup_(sd_device_unrefp) sd_device *child = NULL;
+                _cleanup_free_ char *p = NULL;
+
+                if (dot_or_dot_dot(de->d_name))
+                        continue;
+
+                if (!IN_SET(de->d_type, DT_LNK, DT_DIR))
+                        continue;
+
+                if (subdir)
+                        p = path_join(subdir, de->d_name);
+                else
+                        p = strdup(de->d_name);
+                if (!p)
+                        return -ENOMEM;
+
+                /* Try to create child device. */
+                r = sd_device_new_child(&child, device, p);
+                if (r >= 0) {
+                        /* OK, this is a child device, saving it. */
+                        r = hashmap_ensure_put(children, &device_by_path_hash_ops, p, child);
+                        if (r < 0)
+                                return r;
+
+                        TAKE_PTR(p);
+                        TAKE_PTR(child);
+                } else if (r == -ENODEV) {
+                        /* This is not a child device. Push the sub-directory into stack, and read it later. */
+
+                        if (de->d_type == DT_LNK)
+                                /* Do not follow symlinks, otherwise, we will enter an infinite loop, e.g.,
+                                 * /sys/class/block/nvme0n1/subsystem/nvme0n1/subsystem/nvme0n1/subsystem/… */
+                                continue;
+
+                        r = set_ensure_consume(stack, &path_hash_ops_free, TAKE_PTR(p));
+                        if (r < 0)
+                                return r;
+                } else
+                        return r;
+        }
+
+        return 0;
+}
+
+static int device_enumerate_children(sd_device *device) {
+        _cleanup_hashmap_free_ Hashmap *children = NULL;
+        _cleanup_set_free_ Set *stack = NULL;
+        int r;
+
+        assert(device);
+
+        if (device->children_enumerated)
+                return 0; /* Already enumerated. */
+
+        r = device_enumerate_children_internal(device, NULL, &stack, &children);
+        if (r < 0)
+                return r;
+
+        for (;;) {
+                _cleanup_free_ char *subdir = NULL;
+
+                subdir = set_steal_first(stack);
+                if (!subdir)
+                        break;
+
+                r = device_enumerate_children_internal(device, subdir, &stack, &children);
+                if (r < 0)
+                        return r;
+        }
+
+        device->children_enumerated = true;
+        device->children = TAKE_PTR(children);
+        return 1; /* Enumerated. */
+}
+
+_public_ sd_device *sd_device_get_child_first(sd_device *device, const char **ret_suffix) {
+        int r;
+
+        assert(device);
+
+        r = device_enumerate_children(device);
+        if (r < 0) {
+                log_device_debug_errno(device, r, "sd-device: failed to enumerate child devices: %m");
+                if (ret_suffix)
+                        *ret_suffix = NULL;
+                return NULL;
+        }
+
+        device->children_iterator = ITERATOR_FIRST;
+
+        return sd_device_get_child_next(device, ret_suffix);
+}
+
+_public_ sd_device *sd_device_get_child_next(sd_device *device, const char **ret_suffix) {
+        sd_device *child;
+
+        assert(device);
+
+        (void) hashmap_iterate(device->children, &device->children_iterator, (void**) &child, (const void**) ret_suffix);
+        return child;
+}
+
+_public_ int sd_device_new_child(sd_device **ret, sd_device *device, const char *suffix) {
+        _cleanup_free_ char *path = NULL;
+        sd_device *child;
+        const char *s;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(device, -EINVAL);
+        assert_return(suffix, -EINVAL);
+
+        if (!path_is_safe(suffix))
+                return -EINVAL;
+
+        /* If we have already enumerated children, try to find the child from the cache. */
+        child = hashmap_get(device->children, suffix);
+        if (child) {
+                *ret = sd_device_ref(child);
+                return 0;
+        }
+
+        r = sd_device_get_syspath(device, &s);
+        if (r < 0)
+                return r;
+
+        path = path_join(s, suffix);
+        if (!path)
+                return -ENOMEM;
+
+        return sd_device_new_from_syspath(ret, path);
+}
+
+static int device_new_from_child(sd_device **ret, sd_device *child) {
+        _cleanup_free_ char *path = NULL;
+        const char *syspath;
+        int r;
+
+        assert(ret);
+        assert(child);
+
+        r = sd_device_get_syspath(child, &syspath);
+        if (r < 0)
+                return r;
+
+        for (;;) {
+                _cleanup_free_ char *p = NULL;
+
+                r = path_extract_directory(path ?: syspath, &p);
+                if (r < 0)
+                        return r;
+
+                if (path_equal(p, "/sys"))
+                        return -ENODEV;
+
+                r = sd_device_new_from_syspath(ret, p);
+                if (r != -ENODEV)
+                        return r;
+
+                free_and_replace(path, p);
+        }
+}
+
+_public_ int sd_device_get_parent(sd_device *child, sd_device **ret) {
+        int r;
+
+        assert_return(child, -EINVAL);
+
+        if (!child->parent_set) {
+                r = device_new_from_child(&child->parent, child);
+                if (r < 0 && r != -ENODEV)
+                        return r;
+
+                child->parent_set = true;
+        }
+
+        if (!child->parent)
+                return -ENOENT;
+
+        if (ret)
+                *ret = child->parent;
+        return 0;
+}
+
+int device_set_subsystem(sd_device *device, const char *subsystem) {
+        _cleanup_free_ char *s = NULL;
+        int r;
+
+        assert(device);
+
+        if (subsystem) {
+                s = strdup(subsystem);
+                if (!s)
+                        return -ENOMEM;
+        }
+
+        r = device_add_property_internal(device, "SUBSYSTEM", s);
+        if (r < 0)
+                return r;
+
+        device->subsystem_set = true;
+        return free_and_replace(device->subsystem, s);
+}
+
+int device_set_drivers_subsystem(sd_device *device) {
+        _cleanup_free_ char *subsystem = NULL;
+        const char *devpath, *drivers, *p;
+        int r;
+
+        assert(device);
+
+        r = sd_device_get_devpath(device, &devpath);
+        if (r < 0)
+                return r;
+
+        drivers = strstr(devpath, "/drivers/");
+        if (!drivers)
+                drivers = endswith(devpath, "/drivers");
+        if (!drivers)
+                return -EINVAL;
+
+        /* Find the path component immediately before the "/drivers/" string */
+        r = path_find_last_component(devpath, /* accept_dot_dot= */ false, &drivers, &p);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EINVAL;
+
+        subsystem = strndup(p, r);
+        if (!subsystem)
+                return -ENOMEM;
+
+        r = device_set_subsystem(device, "drivers");
+        if (r < 0)
+                return r;
+
+        return free_and_replace(device->driver_subsystem, subsystem);
+}
+
+_public_ int sd_device_get_subsystem(sd_device *device, const char **ret) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        if (!device->subsystem_set) {
+                _cleanup_free_ char *subsystem = NULL;
+                const char *syspath;
+                char *path;
+
+                r = sd_device_get_syspath(device, &syspath);
+                if (r < 0)
+                        return r;
+
+                /* read 'subsystem' link */
+                path = strjoina(syspath, "/subsystem");
+                r = readlink_value(path, &subsystem);
+                if (r < 0 && r != -ENOENT)
+                        return log_device_debug_errno(device, r,
+                                                      "sd-device: Failed to read subsystem for %s: %m",
+                                                      device->devpath);
+
+                if (subsystem)
+                        r = device_set_subsystem(device, subsystem);
+                /* use implicit names */
+                else if (!isempty(path_startswith(device->devpath, "/module/")))
+                        r = device_set_subsystem(device, "module");
+                else if (strstr(syspath, "/drivers/") || endswith(syspath, "/drivers"))
+                        r = device_set_drivers_subsystem(device);
+                else if (!isempty(PATH_STARTSWITH_SET(device->devpath, "/class/", "/bus/")))
+                        r = device_set_subsystem(device, "subsystem");
+                else {
+                        device->subsystem_set = true;
+                        r = 0;
+                }
+                if (r < 0)
+                        return log_device_debug_errno(device, r,
+                                                      "sd-device: Failed to set subsystem for %s: %m",
+                                                      device->devpath);
+        }
+
+        if (!device->subsystem)
+                return -ENOENT;
+
+        if (ret)
+                *ret = device->subsystem;
+        return 0;
+}
+
+_public_ int sd_device_get_devtype(sd_device *device, const char **devtype) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        if (!device->devtype)
+                return -ENOENT;
+
+        if (devtype)
+                *devtype = device->devtype;
+
+        return !!device->devtype;
+}
+
+_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;
+
+                (void) sd_device_get_subsystem(parent, &parent_subsystem);
+                if (streq_ptr(parent_subsystem, subsystem)) {
+                        const char *parent_devtype = NULL;
+
+                        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;
+
+        if (ret)
+                *ret = parent;
+        return 0;
+}
+
+_public_ int sd_device_get_devnum(sd_device *device, dev_t *devnum) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        if (major(device->devnum) <= 0)
+                return -ENOENT;
+
+        if (devnum)
+                *devnum = device->devnum;
+
+        return 0;
+}
+
+int device_set_driver(sd_device *device, const char *driver) {
+        _cleanup_free_ char *d = NULL;
+        int r;
+
+        assert(device);
+
+        if (driver) {
+                d = strdup(driver);
+                if (!d)
+                        return -ENOMEM;
+        }
+
+        r = device_add_property_internal(device, "DRIVER", d);
+        if (r < 0)
+                return r;
+
+        device->driver_set = true;
+        return free_and_replace(device->driver, d);
+}
+
+_public_ int sd_device_get_driver(sd_device *device, const char **ret) {
+        assert_return(device, -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 != -ENOENT)
+                        return log_device_debug_errno(device, r,
+                                                      "sd-device: readlink(\"%s\") failed: %m", path);
+
+                r = device_set_driver(device, driver);
+                if (r < 0)
+                        return log_device_debug_errno(device, r,
+                                                      "sd-device: Failed to set driver \"%s\": %m", driver);
+        }
+
+        if (!device->driver)
+                return -ENOENT;
+
+        if (ret)
+                *ret = device->driver;
+        return 0;
+}
+
+_public_ int sd_device_get_devpath(sd_device *device, const char **ret) {
+        assert_return(device, -EINVAL);
+
+        assert(device->devpath);
+        assert(device->devpath[0] == '/');
+
+        if (ret)
+                *ret = device->devpath;
+
+        return 0;
+}
+
+_public_ int sd_device_get_devname(sd_device *device, const char **devname) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        if (!device->devname)
+                return -ENOENT;
+
+        assert(!isempty(path_startswith(device->devname, "/dev/")));
+
+        if (devname)
+                *devname = device->devname;
+        return 0;
+}
+
+static int device_set_sysname_and_sysnum(sd_device *device) {
+        _cleanup_free_ char *sysname = NULL;
+        size_t len, n;
+        int r;
+
+        assert(device);
+
+        r = path_extract_filename(device->devpath, &sysname);
+        if (r < 0)
+                return r;
+        if (r == O_DIRECTORY)
+                return -EINVAL;
+
+        /* some devices have '!' in their name, change that to '/' */
+        string_replace_char(sysname, '!', '/');
+
+        n = strspn_from_end(sysname, DIGITS);
+        len = strlen(sysname);
+        assert(n <= len);
+        if (n == len)
+                n = 0; /* Do not set sysnum for number only sysname. */
+
+        device->sysnum = n > 0 ? sysname + len - n : NULL;
+        return free_and_replace(device->sysname, sysname);
+}
+
+_public_ int sd_device_get_sysname(sd_device *device, const char **ret) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        if (!device->sysname) {
+                r = device_set_sysname_and_sysnum(device);
+                if (r < 0)
+                        return r;
+        }
+
+        if (ret)
+                *ret = device->sysname;
+        return 0;
+}
+
+_public_ int sd_device_get_sysnum(sd_device *device, const char **ret) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        if (!device->sysname) {
+                r = device_set_sysname_and_sysnum(device);
+                if (r < 0)
+                        return r;
+        }
+
+        if (!device->sysnum)
+                return -ENOENT;
+
+        if (ret)
+                *ret = device->sysnum;
+        return 0;
+}
+
+_public_ int sd_device_get_action(sd_device *device, sd_device_action_t *ret) {
+        assert_return(device, -EINVAL);
+
+        if (device->action < 0)
+                return -ENOENT;
+
+        if (ret)
+                *ret = device->action;
+
+        return 0;
+}
+
+_public_ int sd_device_get_seqnum(sd_device *device, uint64_t *ret) {
+        assert_return(device, -EINVAL);
+
+        if (device->seqnum == 0)
+                return -ENOENT;
+
+        if (ret)
+                *ret = device->seqnum;
+
+        return 0;
+}
+
+_public_ int sd_device_get_diskseq(sd_device *device, uint64_t *ret) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        r = device_read_uevent_file(device);
+        if (r < 0)
+                return r;
+
+        if (device->diskseq == 0)
+                return -ENOENT;
+
+        if (ret)
+                *ret = device->diskseq;
+
+        return 0;
+}
+
+static bool is_valid_tag(const char *tag) {
+        assert(tag);
+
+        return in_charset(tag, ALPHANUMERICAL "-_") && filename_is_valid(tag);
+}
+
+int device_add_tag(sd_device *device, const char *tag, bool both) {
+        int r, added;
+
+        assert(device);
+        assert(tag);
+
+        if (!is_valid_tag(tag))
+                return -EINVAL;
+
+        /* Definitely add to the "all" list of tags (i.e. the sticky list) */
+        added = set_put_strdup(&device->all_tags, tag);
+        if (added < 0)
+                return added;
+
+        /* And optionally, also add it to the current list of tags */
+        if (both) {
+                r = set_put_strdup(&device->current_tags, tag);
+                if (r < 0) {
+                        if (added > 0)
+                                (void) set_remove(device->all_tags, tag);
+
+                        return r;
+                }
+        }
+
+        device->tags_generation++;
+        device->property_tags_outdated = true;
+
+        return 0;
+}
+
+int device_add_devlink(sd_device *device, const char *devlink) {
+        char *p;
+        int r;
+
+        assert(device);
+        assert(devlink);
+
+        r = mangle_devname(devlink, &p);
+        if (r < 0)
+                return r;
+
+        r = set_ensure_consume(&device->devlinks, &path_hash_ops_free, p);
+        if (r < 0)
+                return r;
+
+        device->devlinks_generation++;
+        device->property_devlinks_outdated = true;
+
+        return r; /* return 1 when newly added, 0 when already exists */
+}
+
+int device_remove_devlink(sd_device *device, const char *devlink) {
+        _cleanup_free_ char *p = NULL, *s = NULL;
+        int r;
+
+        assert(device);
+        assert(devlink);
+
+        r = mangle_devname(devlink, &p);
+        if (r < 0)
+                return r;
+
+        s = set_remove(device->devlinks, p);
+        if (!s)
+                return 0; /* does not exist */
+
+        device->devlinks_generation++;
+        device->property_devlinks_outdated = true;
+        return 1; /* removed */
+}
+
+bool device_has_devlink(sd_device *device, const char *devlink) {
+        assert(device);
+        assert(devlink);
+
+        return set_contains(device->devlinks, devlink);
+}
+
+static int device_add_property_internal_from_string(sd_device *device, const char *str) {
+        _cleanup_free_ char *key = NULL;
+        char *value;
+        int r;
+
+        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;
+
+        /* Add the property to both sd_device::properties and sd_device::properties_db,
+         * as this is called by only handle_db_line(). */
+        r = device_add_property_aux(device, key, value, false);
+        if (r < 0)
+                return r;
+
+        return device_add_property_aux(device, key, value, true);
+}
+
+int device_set_usec_initialized(sd_device *device, usec_t when) {
+        char s[DECIMAL_STR_MAX(usec_t)];
+        int r;
+
+        assert(device);
+
+        xsprintf(s, USEC_FMT, when);
+
+        r = device_add_property_internal(device, "USEC_INITIALIZED", s);
+        if (r < 0)
+                return r;
+
+        device->usec_initialized = when;
+        return 0;
+}
+
+static int handle_db_line(sd_device *device, char key, const char *value) {
+        int r;
+
+        assert(device);
+        assert(value);
+
+        switch (key) {
+        case 'G': /* Any tag */
+        case 'Q': /* Current tag */
+                return device_add_tag(device, value, key == 'Q');
+
+        case 'S': {
+                const char *path;
+
+                path = strjoina("/dev/", value);
+                return device_add_devlink(device, path);
+        }
+        case 'E':
+                return device_add_property_internal_from_string(device, value);
+
+        case 'I': {
+                usec_t t;
+
+                r = safe_atou64(value, &t);
+                if (r < 0)
+                        return r;
+
+                return device_set_usec_initialized(device, t);
+        }
+        case 'L':
+                return safe_atoi(value, &device->devlink_priority);
+
+        case 'W':
+                /* Deprecated. Previously, watch handle is both saved in database and /run/udev/watch.
+                 * However, the handle saved in database may not be updated when the handle is updated
+                 * or removed. Moreover, it is not necessary to store the handle within the database,
+                 * as its value becomes meaningless when udevd is restarted. */
+                return 0;
+
+        case 'V':
+                return safe_atou(value, &device->database_version);
+
+        default:
+                log_device_debug(device, "sd-device: Unknown key '%c' in device db, ignoring", key);
+                return 0;
+        }
+}
+
+int device_get_device_id(sd_device *device, const char **ret) {
+        assert(device);
+        assert(ret);
+
+        if (!device->device_id) {
+                _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;
+
+                if (sd_device_get_devnum(device, &devnum) >= 0) {
+                        /* use dev_t — b259:131072, c254:0 */
+                        if (asprintf(&id, "%c" DEVNUM_FORMAT_STR,
+                                     streq(subsystem, "block") ? 'b' : 'c',
+                                     DEVNUM_FORMAT_VAL(devnum)) < 0)
+                                return -ENOMEM;
+                } else if (sd_device_get_ifindex(device, &ifindex) >= 0) {
+                        /* use netdev ifindex — n3 */
+                        if (asprintf(&id, "n%u", (unsigned) ifindex) < 0)
+                                return -ENOMEM;
+                } else {
+                        _cleanup_free_ char *sysname = NULL;
+
+                        /* use $subsys:$sysname — pci:0000:00:1f.2
+                         * sd_device_get_sysname() has '!' translated, get it from devpath */
+                        r = path_extract_filename(device->devpath, &sysname);
+                        if (r < 0)
+                                return r;
+                        if (r == O_DIRECTORY)
+                                return -EINVAL;
+
+                        if (streq(subsystem, "drivers")) {
+                                /* the 'drivers' pseudo-subsystem is special, and needs the real
+                                 * subsystem encoded as well */
+                                assert(device->driver_subsystem);
+                                id = strjoin("+drivers:", device->driver_subsystem, ":", sysname);
+                        } else
+                                id = strjoin("+", subsystem, ":", sysname);
+                        if (!id)
+                                return -ENOMEM;
+                }
+
+                if (!filename_is_valid(id))
+                        return -EINVAL;
+
+                device->device_id = TAKE_PTR(id);
+        }
+
+        *ret = device->device_id;
+        return 0;
+}
+
+int device_read_db_internal_filename(sd_device *device, const char *filename) {
+        _cleanup_free_ char *db = NULL;
+        const char *value;
+        size_t db_len;
+        char key = '\0';  /* Unnecessary initialization to appease gcc-12.0.0-0.4.fc36 */
+        int r;
+
+        enum {
+                PRE_KEY,
+                KEY,
+                PRE_VALUE,
+                VALUE,
+                INVALID_LINE,
+        } state = PRE_KEY;
+
+        assert(device);
+        assert(filename);
+
+        r = read_full_file(filename, &db, &db_len);
+        if (r < 0) {
+                if (r == -ENOENT)
+                        return 0;
+
+                return log_device_debug_errno(device, r, "sd-device: Failed to read db '%s': %m", filename);
+        }
+
+        /* devices with a database entry are initialized */
+        device->is_initialized = true;
+
+        device->db_loaded = true;
+
+        for (size_t 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_device_debug(device, "sd-device: Invalid db entry with key '%c', ignoring", 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_device_debug_errno(device, r, "sd-device: Failed to handle db entry '%c:%s', ignoring: %m",
+                                                               key, value);
+
+                                state = PRE_KEY;
+                        }
+
+                        break;
+                default:
+                        return log_device_debug_errno(device, SYNTHETIC_ERRNO(EINVAL), "sd-device: invalid db syntax.");
+                }
+
+        return 0;
+}
+
+int device_read_db_internal(sd_device *device, bool force) {
+        const char *id, *path;
+        int r;
+
+        assert(device);
+
+        if (device->db_loaded || (!force && device->sealed))
+                return 0;
+
+        r = device_get_device_id(device, &id);
+        if (r < 0)
+                return r;
+
+        path = strjoina("/run/udev/data/", id);
+
+        return device_read_db_internal_filename(device, path);
+}
+
+_public_ int sd_device_get_is_initialized(sd_device *device) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        r = device_read_db(device);
+        if (r == -ENOENT)
+                /* The device may be already removed or renamed. */
+                return false;
+        if (r < 0)
+                return r;
+
+        return device->is_initialized;
+}
+
+_public_ int sd_device_get_usec_initialized(sd_device *device, uint64_t *ret) {
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        r = sd_device_get_is_initialized(device);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EBUSY;
+
+        if (device->usec_initialized == 0)
+                return -ENODATA;
+
+        if (ret)
+                *ret = device->usec_initialized;
+
+        return 0;
+}
+
+_public_ int sd_device_get_usec_since_initialized(sd_device *device, uint64_t *ret) {
+        usec_t now_ts, ts;
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        r = sd_device_get_usec_initialized(device, &ts);
+        if (r < 0)
+                return r;
+
+        now_ts = now(CLOCK_MONOTONIC);
+
+        if (now_ts < ts)
+                return -EIO;
+
+        if (ret)
+                *ret = usec_sub_unsigned(now_ts, ts);
+
+        return 0;
+}
+
+_public_ const char *sd_device_get_tag_first(sd_device *device) {
+        void *v;
+
+        assert_return(device, NULL);
+
+        (void) device_read_db(device);
+
+        device->all_tags_iterator_generation = device->tags_generation;
+        device->all_tags_iterator = ITERATOR_FIRST;
+
+        (void) set_iterate(device->all_tags, &device->all_tags_iterator, &v);
+        return v;
+}
+
+_public_ const char *sd_device_get_tag_next(sd_device *device) {
+        void *v;
+
+        assert_return(device, NULL);
+
+        (void) device_read_db(device);
+
+        if (device->all_tags_iterator_generation != device->tags_generation)
+                return NULL;
+
+        (void) set_iterate(device->all_tags, &device->all_tags_iterator, &v);
+        return v;
+}
+
+static bool device_database_supports_current_tags(sd_device *device) {
+        assert(device);
+
+        (void) device_read_db(device);
+
+        /* The current tags (saved in Q field) feature is implemented in database version 1.
+         * If the database version is 0, then the tags (NOT current tags, saved in G field) are not
+         * sticky. Thus, we can safely bypass the operations for the current tags (Q) to tags (G). */
+
+        return device->database_version >= 1;
+}
+
+_public_ const char *sd_device_get_current_tag_first(sd_device *device) {
+        void *v;
+
+        assert_return(device, NULL);
+
+        if (!device_database_supports_current_tags(device))
+                return sd_device_get_tag_first(device);
+
+        (void) device_read_db(device);
+
+        device->current_tags_iterator_generation = device->tags_generation;
+        device->current_tags_iterator = ITERATOR_FIRST;
+
+        (void) set_iterate(device->current_tags, &device->current_tags_iterator, &v);
+        return v;
+}
+
+_public_ const char *sd_device_get_current_tag_next(sd_device *device) {
+        void *v;
+
+        assert_return(device, NULL);
+
+        if (!device_database_supports_current_tags(device))
+                return sd_device_get_tag_next(device);
+
+        (void) device_read_db(device);
+
+        if (device->current_tags_iterator_generation != device->tags_generation)
+                return NULL;
+
+        (void) set_iterate(device->current_tags, &device->current_tags_iterator, &v);
+        return v;
+}
+
+_public_ const char *sd_device_get_devlink_first(sd_device *device) {
+        void *v;
+
+        assert_return(device, NULL);
+
+        (void) device_read_db(device);
+
+        device->devlinks_iterator_generation = device->devlinks_generation;
+        device->devlinks_iterator = ITERATOR_FIRST;
+
+        (void) set_iterate(device->devlinks, &device->devlinks_iterator, &v);
+        return v;
+}
+
+_public_ const char *sd_device_get_devlink_next(sd_device *device) {
+        void *v;
+
+        assert_return(device, NULL);
+
+        (void) device_read_db(device);
+
+        if (device->devlinks_iterator_generation != device->devlinks_generation)
+                return NULL;
+
+        (void) set_iterate(device->devlinks, &device->devlinks_iterator, &v);
+        return v;
+}
+
+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) {
+                _cleanup_free_ char *devlinks = NULL;
+
+                r = set_strjoin(device->devlinks, " ", false, &devlinks);
+                if (r < 0)
+                        return r;
+
+                if (!isempty(devlinks)) {
+                        r = device_add_property_internal(device, "DEVLINKS", devlinks);
+                        if (r < 0)
+                                return r;
+                }
+
+                device->property_devlinks_outdated = false;
+        }
+
+        if (device->property_tags_outdated) {
+                _cleanup_free_ char *tags = NULL;
+
+                r = set_strjoin(device->all_tags, ":", true, &tags);
+                if (r < 0)
+                        return r;
+
+                if (!isempty(tags)) {
+                        r = device_add_property_internal(device, "TAGS", tags);
+                        if (r < 0)
+                                return r;
+                }
+
+                tags = mfree(tags);
+                r = set_strjoin(device->current_tags, ":", true, &tags);
+                if (r < 0)
+                        return r;
+
+                if (!isempty(tags)) {
+                        r = device_add_property_internal(device, "CURRENT_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;
+        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;
+
+        (void) ordered_hashmap_iterate(device->properties, &device->properties_iterator, (void**)_value, (const void**)&key);
+        return key;
+}
+
+_public_ const char *sd_device_get_property_next(sd_device *device, const char **_value) {
+        const char *key;
+        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;
+
+        (void) ordered_hashmap_iterate(device->properties, &device->properties_iterator, (void**)_value, (const void**)&key);
+        return key;
+}
+
+static int device_sysattrs_read_all_internal(sd_device *device, const char *subdir, Set **stack) {
+        _cleanup_closedir_ DIR *dir = NULL;
+        int r;
+
+        assert(device);
+        assert(stack);
+
+        r = device_opendir(device, subdir, &dir);
+        if (r == -ENOENT && subdir)
+                return 0; /* Maybe, this is a child device, and is already removed. */
+        if (r < 0)
+                return r;
+
+        if (subdir) {
+                if (faccessat(dirfd(dir), "uevent", F_OK, 0) >= 0)
+                        return 0; /* this is a child device, skipping */
+                if (errno != ENOENT) {
+                        log_device_debug_errno(device, errno,
+                                               "sd-device: Failed to access %s/uevent, ignoring sub-directory %s: %m",
+                                               subdir, subdir);
+                        return 0;
+                }
+        }
+
+        FOREACH_DIRENT_ALL(de, dir, return -errno) {
+                _cleanup_free_ char *p = NULL;
+                struct stat statbuf;
+
+                if (dot_or_dot_dot(de->d_name))
+                        continue;
+
+                /* only handle symlinks, regular files, and directories */
+                if (!IN_SET(de->d_type, DT_LNK, DT_REG, DT_DIR))
+                        continue;
+
+                if (subdir) {
+                        p = path_join(subdir, de->d_name);
+                        if (!p)
+                                return -ENOMEM;
+                }
+
+                if (de->d_type == DT_DIR) {
+                        /* push the sub-directory into the stack, and read it later. */
+                        if (p)
+                                r = set_ensure_consume(stack, &path_hash_ops_free, TAKE_PTR(p));
+                        else
+                                r = set_put_strdup_full(stack, &path_hash_ops_free, de->d_name);
+                        if (r < 0)
+                                return r;
+
+                        continue;
+                }
+
+                if (fstatat(dirfd(dir), de->d_name, &statbuf, AT_SYMLINK_NOFOLLOW) < 0)
+                        continue;
+
+                if ((statbuf.st_mode & (S_IRUSR | S_IWUSR)) == 0)
+                        continue;
+
+                if (p)
+                        r = set_ensure_consume(&device->sysattrs, &path_hash_ops_free, TAKE_PTR(p));
+                else
+                        r = set_put_strdup_full(&device->sysattrs, &path_hash_ops_free, de->d_name);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int device_sysattrs_read_all(sd_device *device) {
+        _cleanup_set_free_ Set *stack = NULL;
+        int r;
+
+        assert(device);
+
+        if (device->sysattrs_read)
+                return 0;
+
+        r = device_sysattrs_read_all_internal(device, NULL, &stack);
+        if (r < 0)
+                return r;
+
+        for (;;) {
+                _cleanup_free_ char *subdir = NULL;
+
+                subdir = set_steal_first(stack);
+                if (!subdir)
+                        break;
+
+                r = device_sysattrs_read_all_internal(device, subdir, &stack);
+                if (r < 0)
+                        return r;
+        }
+
+        device->sysattrs_read = true;
+
+        return 0;
+}
+
+_public_ const char *sd_device_get_sysattr_first(sd_device *device) {
+        void *v;
+        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;
+
+        (void) set_iterate(device->sysattrs, &device->sysattrs_iterator, &v);
+        return v;
+}
+
+_public_ const char *sd_device_get_sysattr_next(sd_device *device) {
+        void *v;
+
+        assert_return(device, NULL);
+
+        if (!device->sysattrs_read)
+                return NULL;
+
+        (void) set_iterate(device->sysattrs, &device->sysattrs_iterator, &v);
+        return v;
+}
+
+_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->all_tags, tag);
+}
+
+_public_ int sd_device_has_current_tag(sd_device *device, const char *tag) {
+        assert_return(device, -EINVAL);
+        assert_return(tag, -EINVAL);
+
+        if (!device_database_supports_current_tags(device))
+                return sd_device_has_tag(device, tag);
+
+        (void) device_read_db(device);
+
+        return set_contains(device->current_tags, tag);
+}
+
+_public_ int sd_device_get_property_value(sd_device *device, const char *key, const char **ret_value) {
+        const char *value;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(key, -EINVAL);
+
+        r = device_properties_prepare(device);
+        if (r < 0)
+                return r;
+
+        value = ordered_hashmap_get(device->properties, key);
+        if (!value)
+                return -ENOENT;
+
+        if (ret_value)
+                *ret_value = value;
+        return 0;
+}
+
+int device_get_property_bool(sd_device *device, const char *key) {
+        const char *value;
+        int r;
+
+        assert(device);
+        assert(key);
+
+        r = sd_device_get_property_value(device, key, &value);
+        if (r < 0)
+                return r;
+
+        return parse_boolean(value);
+}
+
+int device_get_property_int(sd_device *device, const char *key, int *ret) {
+        const char *value;
+        int r, v;
+
+        assert(device);
+        assert(key);
+
+        r = sd_device_get_property_value(device, key, &value);
+        if (r < 0)
+                return r;
+
+        r = safe_atoi(value, &v);
+        if (r < 0)
+                return r;
+
+        if (ret)
+                *ret = v;
+        return 0;
+}
+
+_public_ int sd_device_get_trigger_uuid(sd_device *device, sd_id128_t *ret) {
+        const char *s;
+        sd_id128_t id;
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        /* Retrieves the UUID attached to a uevent when triggering it from userspace via
+         * sd_device_trigger_with_uuid() or an equivalent interface. Returns -ENOENT if the record is not
+         * caused by a synthetic event and -ENODATA if it was but no UUID was specified */
+
+        r = sd_device_get_property_value(device, "SYNTH_UUID", &s);
+        if (r < 0)
+                return r;
+
+        if (streq(s, "0")) /* SYNTH_UUID=0 is set whenever a device is triggered by userspace without specifying a UUID */
+                return -ENODATA;
+
+        r = sd_id128_from_string(s, &id);
+        if (r < 0)
+                return r;
+
+        if (ret)
+                *ret = id;
+
+        return 0;
+}
+
+void device_clear_sysattr_cache(sd_device *device) {
+        device->sysattr_values = hashmap_free(device->sysattr_values);
+}
+
+int device_cache_sysattr_value(sd_device *device, const char *key, char *value) {
+        _unused_ _cleanup_free_ char *old_value = NULL;
+        _cleanup_free_ char *new_key = NULL;
+        int r;
+
+        assert(device);
+        assert(key);
+
+        /* This takes the reference of the input value. The input value may be NULL.
+         * This replaces the value if it already exists. */
+
+        /* First, remove the old cache entry. So, we do not need to clear cache on error. */
+        old_value = hashmap_remove2(device->sysattr_values, key, (void **) &new_key);
+        if (!new_key) {
+                new_key = strdup(key);
+                if (!new_key)
+                        return -ENOMEM;
+        }
+
+        r = hashmap_ensure_put(&device->sysattr_values, &path_hash_ops_free_free, new_key, value);
+        if (r < 0)
+                return r;
+
+        TAKE_PTR(new_key);
+
+        return 0;
+}
+
+int device_get_cached_sysattr_value(sd_device *device, const char *key, const char **ret_value) {
+        const char *k = NULL, *value;
+
+        assert(device);
+        assert(key);
+
+        value = hashmap_get2(device->sysattr_values, key, (void **) &k);
+        if (!k)
+                return -ESTALE; /* We have not read the attribute. */
+        if (!value)
+                return -ENOENT; /* We have looked up the attribute before and it did not exist. */
+        if (ret_value)
+                *ret_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 **ret_value) {
+        _cleanup_free_ char *value = NULL, *path = NULL;
+        const char *syspath;
+        struct stat statbuf;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(sysattr, -EINVAL);
+
+        /* look for possibly already cached result */
+        r = device_get_cached_sysattr_value(device, sysattr, ret_value);
+        if (r != -ESTALE)
+                return r;
+
+        r = sd_device_get_syspath(device, &syspath);
+        if (r < 0)
+                return r;
+
+        path = path_join(syspath, sysattr);
+        if (!path)
+                return -ENOMEM;
+
+        if (lstat(path, &statbuf) < 0) {
+                int k;
+
+                r = -errno;
+
+                /* remember that we could not access the sysattr */
+                k = device_cache_sysattr_value(device, sysattr, NULL);
+                if (k < 0)
+                        log_device_debug_errno(device, k,
+                                               "sd-device: failed to cache attribute '%s' with NULL, ignoring: %m",
+                                               sysattr);
+
+                return r;
+        } 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 -EISDIR;
+        else if (!(statbuf.st_mode & S_IRUSR))
+                /* skip non-readable files */
+                return -EPERM;
+        else {
+                size_t size;
+
+                /* Read attribute value, Some attributes contain embedded '\0'. So, it is necessary to
+                 * also get the size of the result. See issue #20025. */
+                r = read_full_virtual_file(path, &value, &size);
+                if (r < 0)
+                        return r;
+
+                /* drop trailing newlines */
+                while (size > 0 && strchr(NEWLINE, value[--size]))
+                        value[size] = '\0';
+        }
+
+        /* Unfortunately, we need to return 'const char*' instead of 'char*'. Hence, failure in caching
+         * sysattr value is critical unlike the other places. */
+        r = device_cache_sysattr_value(device, sysattr, value);
+        if (r < 0) {
+                log_device_debug_errno(device, r,
+                                       "sd-device: failed to cache attribute '%s' with '%s'%s: %m",
+                                       sysattr, value, ret_value ? "" : ", ignoring");
+                if (ret_value)
+                        return r;
+
+                return 0;
+        }
+
+        if (ret_value)
+                *ret_value = value;
+
+        TAKE_PTR(value);
+        return 0;
+}
+
+int device_get_sysattr_int(sd_device *device, const char *sysattr, int *ret_value) {
+        const char *value;
+        int r;
+
+        r = sd_device_get_sysattr_value(device, sysattr, &value);
+        if (r < 0)
+                return r;
+
+        int v;
+        r = safe_atoi(value, &v);
+        if (r < 0)
+                return log_device_debug_errno(device, r, "Failed to parse '%s' attribute: %m", sysattr);
+
+        if (ret_value)
+                *ret_value = v;
+        /* We return "true" if the value is positive. */
+        return v > 0;
+}
+
+int device_get_sysattr_unsigned(sd_device *device, const char *sysattr, unsigned *ret_value) {
+        const char *value;
+        int r;
+
+        r = sd_device_get_sysattr_value(device, sysattr, &value);
+        if (r < 0)
+                return r;
+
+        unsigned v;
+        r = safe_atou(value, &v);
+        if (r < 0)
+                return log_device_debug_errno(device, r, "Failed to parse '%s' attribute: %m", sysattr);
+
+        if (ret_value)
+                *ret_value = v;
+        /* We return "true" if the value is positive. */
+        return v > 0;
+}
+
+int device_get_sysattr_bool(sd_device *device, const char *sysattr) {
+        const char *value;
+        int r;
+
+        assert(device);
+        assert(sysattr);
+
+        r = sd_device_get_sysattr_value(device, sysattr, &value);
+        if (r < 0)
+                return r;
+
+        return parse_boolean(value);
+}
+
+static void device_remove_cached_sysattr_value(sd_device *device, const char *_key) {
+        _cleanup_free_ char *key = NULL;
+
+        assert(device);
+        assert(_key);
+
+        free(hashmap_remove2(device->sysattr_values, _key, (void **) &key));
+}
+
+_public_ int sd_device_set_sysattr_value(sd_device *device, const char *sysattr, const char *_value) {
+        _cleanup_free_ char *value = NULL, *path = NULL;
+        const char *syspath;
+        size_t len;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(sysattr, -EINVAL);
+
+        /* Set the attribute and save it in the cache. */
+
+        if (!_value) {
+                /* If input value is NULL, then clear cache and not write anything. */
+                device_remove_cached_sysattr_value(device, sysattr);
+                return 0;
+        }
+
+        r = sd_device_get_syspath(device, &syspath);
+        if (r < 0)
+                return r;
+
+        path = path_join(syspath, sysattr);
+        if (!path)
+                return -ENOMEM;
+
+        len = strlen(_value);
+
+        /* drop trailing newlines */
+        while (len > 0 && strchr(NEWLINE, _value[len - 1]))
+                len --;
+
+        /* value length is limited to 4k */
+        if (len > 4096)
+                return -EINVAL;
+
+        value = strndup(_value, len);
+        if (!value)
+                return -ENOMEM;
+
+        r = write_string_file(path, value, WRITE_STRING_FILE_DISABLE_BUFFER | WRITE_STRING_FILE_NOFOLLOW);
+        if (r < 0) {
+                /* On failure, clear cache entry, as we do not know how it fails. */
+                device_remove_cached_sysattr_value(device, sysattr);
+                return r;
+        }
+
+        /* Do not cache action string written into uevent file. */
+        if (streq(sysattr, "uevent"))
+                return 0;
+
+        r = device_cache_sysattr_value(device, sysattr, value);
+        if (r < 0)
+                log_device_debug_errno(device, r,
+                                       "sd-device: failed to cache attribute '%s' with '%s', ignoring: %m",
+                                       sysattr, value);
+        else
+                TAKE_PTR(value);
+
+        return 0;
+}
+
+_public_ int sd_device_set_sysattr_valuef(sd_device *device, const char *sysattr, const char *format, ...) {
+        _cleanup_free_ char *value = NULL;
+        va_list ap;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(sysattr, -EINVAL);
+
+        if (!format) {
+                device_remove_cached_sysattr_value(device, sysattr);
+                return 0;
+        }
+
+        va_start(ap, format);
+        r = vasprintf(&value, format, ap);
+        va_end(ap);
+
+        if (r < 0)
+                return -ENOMEM;
+
+        return sd_device_set_sysattr_value(device, sysattr, value);
+}
+
+_public_ int sd_device_trigger(sd_device *device, sd_device_action_t action) {
+        const char *s;
+
+        assert_return(device, -EINVAL);
+
+        s = device_action_to_string(action);
+        if (!s)
+                return -EINVAL;
+
+        /* This uses the simple no-UUID interface of kernel < 4.13 */
+        return sd_device_set_sysattr_value(device, "uevent", s);
+}
+
+_public_ int sd_device_trigger_with_uuid(
+                sd_device *device,
+                sd_device_action_t action,
+                sd_id128_t *ret_uuid) {
+
+        const char *s, *j;
+        sd_id128_t u;
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        /* If no one wants to know the UUID, use the simple interface from pre-4.13 times */
+        if (!ret_uuid)
+                return sd_device_trigger(device, action);
+
+        s = device_action_to_string(action);
+        if (!s)
+                return -EINVAL;
+
+        r = sd_id128_randomize(&u);
+        if (r < 0)
+                return r;
+
+        j = strjoina(s, " ", SD_ID128_TO_UUID_STRING(u));
+
+        r = sd_device_set_sysattr_value(device, "uevent", j);
+        if (r < 0)
+                return r;
+
+        *ret_uuid = u;
+        return 0;
+}
+
+_public_ int sd_device_open(sd_device *device, int flags) {
+        _cleanup_close_ int fd = -EBADF, fd2 = -EBADF;
+        const char *devname, *subsystem = NULL;
+        uint64_t q, diskseq = 0;
+        struct stat st;
+        dev_t devnum;
+        int r;
+
+        assert_return(device, -EINVAL);
+        assert_return(FLAGS_SET(flags, O_PATH) || !FLAGS_SET(flags, O_NOFOLLOW), -EINVAL);
+
+        r = sd_device_get_devname(device, &devname);
+        if (r == -ENOENT)
+                return -ENOEXEC;
+        if (r < 0)
+                return r;
+
+        r = sd_device_get_devnum(device, &devnum);
+        if (r == -ENOENT)
+                return -ENOEXEC;
+        if (r < 0)
+                return r;
+
+        r = sd_device_get_subsystem(device, &subsystem);
+        if (r < 0 && r != -ENOENT)
+                return r;
+
+        fd = open(devname, FLAGS_SET(flags, O_PATH) ? flags : O_CLOEXEC|O_NOFOLLOW|O_PATH);
+        if (fd < 0)
+                return -errno;
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        if (st.st_rdev != devnum)
+                return -ENXIO;
+
+        if (streq_ptr(subsystem, "block") ? !S_ISBLK(st.st_mode) : !S_ISCHR(st.st_mode))
+                return -ENXIO;
+
+        /* If flags has O_PATH, then we cannot check diskseq. Let's return earlier. */
+        if (FLAGS_SET(flags, O_PATH))
+                return TAKE_FD(fd);
+
+        /* If the device is not initialized, then we cannot determine if we should check diskseq through
+         * ID_IGNORE_DISKSEQ property. Let's skip to check diskseq in that case. */
+        r = sd_device_get_is_initialized(device);
+        if (r < 0)
+                return r;
+        if (r > 0) {
+                r = device_get_property_bool(device, "ID_IGNORE_DISKSEQ");
+                if (r < 0 && r != -ENOENT)
+                        return r;
+                if (r <= 0) {
+                        r = sd_device_get_diskseq(device, &diskseq);
+                        if (r < 0 && r != -ENOENT)
+                                return r;
+                }
+        }
+
+        fd2 = fd_reopen(fd, flags);
+        if (fd2 < 0)
+                return fd2;
+
+        if (diskseq == 0)
+                return TAKE_FD(fd2);
+
+        r = fd_get_diskseq(fd2, &q);
+        if (r < 0)
+                return r;
+
+        if (q != diskseq)
+                return -ENXIO;
+
+        return TAKE_FD(fd2);
+}
+
+int device_opendir(sd_device *device, const char *subdir, DIR **ret) {
+        _cleanup_closedir_ DIR *d = NULL;
+        _cleanup_free_ char *path = NULL;
+        const char *syspath;
+        int r;
+
+        assert(device);
+        assert(ret);
+
+        r = sd_device_get_syspath(device, &syspath);
+        if (r < 0)
+                return r;
+
+        if (subdir) {
+                if (!path_is_safe(subdir))
+                        return -EINVAL;
+
+                path = path_join(syspath, subdir);
+                if (!path)
+                        return -ENOMEM;
+        }
+
+        d = opendir(path ?: syspath);
+        if (!d)
+                return -errno;
+
+        *ret = TAKE_PTR(d);
+        return 0;
+}