summaryrefslogtreecommitdiff
path: root/src/libcore/device.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/libcore/device.c')
-rw-r--r--src/libcore/device.c878
1 files changed, 878 insertions, 0 deletions
diff --git a/src/libcore/device.c b/src/libcore/device.c
new file mode 100644
index 0000000000..d201dc5e4b
--- /dev/null
+++ b/src/libcore/device.c
@@ -0,0 +1,878 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+
+ 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 <errno.h>
+#include <sys/epoll.h>
+
+#include "libudev.h"
+
+#include "alloc-util.h"
+#include "dbus-device.h"
+#include "device.h"
+#include "log.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "stat-util.h"
+#include "string-util.h"
+#include "swap.h"
+#include "udev-util.h"
+#include "unit-name.h"
+#include "unit.h"
+
+static const UnitActiveState state_translation_table[_DEVICE_STATE_MAX] = {
+ [DEVICE_DEAD] = UNIT_INACTIVE,
+ [DEVICE_TENTATIVE] = UNIT_ACTIVATING,
+ [DEVICE_PLUGGED] = UNIT_ACTIVE,
+};
+
+static int device_dispatch_io(sd_event_source *source, int fd, uint32_t revents, void *userdata);
+
+static void device_unset_sysfs(Device *d) {
+ Hashmap *devices;
+ Device *first;
+
+ assert(d);
+
+ if (!d->sysfs)
+ return;
+
+ /* Remove this unit from the chain of devices which share the
+ * same sysfs path. */
+ devices = UNIT(d)->manager->devices_by_sysfs;
+ first = hashmap_get(devices, d->sysfs);
+ LIST_REMOVE(same_sysfs, first, d);
+
+ if (first)
+ hashmap_remove_and_replace(devices, d->sysfs, first->sysfs, first);
+ else
+ hashmap_remove(devices, d->sysfs);
+
+ d->sysfs = mfree(d->sysfs);
+}
+
+static int device_set_sysfs(Device *d, const char *sysfs) {
+ Device *first;
+ char *copy;
+ int r;
+
+ assert(d);
+
+ if (streq_ptr(d->sysfs, sysfs))
+ return 0;
+
+ r = hashmap_ensure_allocated(&UNIT(d)->manager->devices_by_sysfs, &string_hash_ops);
+ if (r < 0)
+ return r;
+
+ copy = strdup(sysfs);
+ if (!copy)
+ return -ENOMEM;
+
+ device_unset_sysfs(d);
+
+ first = hashmap_get(UNIT(d)->manager->devices_by_sysfs, sysfs);
+ LIST_PREPEND(same_sysfs, first, d);
+
+ r = hashmap_replace(UNIT(d)->manager->devices_by_sysfs, copy, first);
+ if (r < 0) {
+ LIST_REMOVE(same_sysfs, first, d);
+ free(copy);
+ return r;
+ }
+
+ d->sysfs = copy;
+
+ return 0;
+}
+
+static void device_init(Unit *u) {
+ Device *d = DEVICE(u);
+
+ assert(d);
+ assert(UNIT(d)->load_state == UNIT_STUB);
+
+ /* In contrast to all other unit types we timeout jobs waiting
+ * for devices by default. This is because they otherwise wait
+ * indefinitely for plugged in devices, something which cannot
+ * happen for the other units since their operations time out
+ * anyway. */
+ u->job_timeout = u->manager->default_timeout_start_usec;
+
+ u->ignore_on_isolate = true;
+}
+
+static void device_done(Unit *u) {
+ Device *d = DEVICE(u);
+
+ assert(d);
+
+ device_unset_sysfs(d);
+}
+
+static void device_set_state(Device *d, DeviceState state) {
+ DeviceState old_state;
+ assert(d);
+
+ old_state = d->state;
+ d->state = state;
+
+ if (state != old_state)
+ log_unit_debug(UNIT(d), "Changed %s -> %s", device_state_to_string(old_state), device_state_to_string(state));
+
+ unit_notify(UNIT(d), state_translation_table[old_state], state_translation_table[state], true);
+}
+
+static int device_coldplug(Unit *u) {
+ Device *d = DEVICE(u);
+
+ assert(d);
+ assert(d->state == DEVICE_DEAD);
+
+ if (d->found & DEVICE_FOUND_UDEV)
+ /* If udev says the device is around, it's around */
+ device_set_state(d, DEVICE_PLUGGED);
+ else if (d->found != DEVICE_NOT_FOUND && d->deserialized_state != DEVICE_PLUGGED)
+ /* If a device is found in /proc/self/mountinfo or
+ * /proc/swaps, and was not yet announced via udev,
+ * it's "tentatively" around. */
+ device_set_state(d, DEVICE_TENTATIVE);
+
+ return 0;
+}
+
+static int device_serialize(Unit *u, FILE *f, FDSet *fds) {
+ Device *d = DEVICE(u);
+
+ assert(u);
+ assert(f);
+ assert(fds);
+
+ unit_serialize_item(u, f, "state", device_state_to_string(d->state));
+
+ return 0;
+}
+
+static int device_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
+ Device *d = DEVICE(u);
+
+ assert(u);
+ assert(key);
+ assert(value);
+ assert(fds);
+
+ if (streq(key, "state")) {
+ DeviceState state;
+
+ state = device_state_from_string(value);
+ if (state < 0)
+ log_unit_debug(u, "Failed to parse state value: %s", value);
+ else
+ d->deserialized_state = state;
+ } else
+ log_unit_debug(u, "Unknown serialization key: %s", key);
+
+ return 0;
+}
+
+static void device_dump(Unit *u, FILE *f, const char *prefix) {
+ Device *d = DEVICE(u);
+
+ assert(d);
+
+ fprintf(f,
+ "%sDevice State: %s\n"
+ "%sSysfs Path: %s\n",
+ prefix, device_state_to_string(d->state),
+ prefix, strna(d->sysfs));
+}
+
+_pure_ static UnitActiveState device_active_state(Unit *u) {
+ assert(u);
+
+ return state_translation_table[DEVICE(u)->state];
+}
+
+_pure_ static const char *device_sub_state_to_string(Unit *u) {
+ assert(u);
+
+ return device_state_to_string(DEVICE(u)->state);
+}
+
+static int device_update_description(Unit *u, struct udev_device *dev, const char *path) {
+ const char *model;
+ int r;
+
+ assert(u);
+ assert(dev);
+ assert(path);
+
+ model = udev_device_get_property_value(dev, "ID_MODEL_FROM_DATABASE");
+ if (!model)
+ model = udev_device_get_property_value(dev, "ID_MODEL");
+
+ if (model) {
+ const char *label;
+
+ /* Try to concatenate the device model string with a label, if there is one */
+ label = udev_device_get_property_value(dev, "ID_FS_LABEL");
+ if (!label)
+ label = udev_device_get_property_value(dev, "ID_PART_ENTRY_NAME");
+ if (!label)
+ label = udev_device_get_property_value(dev, "ID_PART_ENTRY_NUMBER");
+
+ if (label) {
+ _cleanup_free_ char *j;
+
+ j = strjoin(model, " ", label, NULL);
+ if (j)
+ r = unit_set_description(u, j);
+ else
+ r = -ENOMEM;
+ } else
+ r = unit_set_description(u, model);
+ } else
+ r = unit_set_description(u, path);
+
+ if (r < 0)
+ log_unit_error_errno(u, r, "Failed to set device description: %m");
+
+ return r;
+}
+
+static int device_add_udev_wants(Unit *u, struct udev_device *dev) {
+ const char *wants;
+ const char *word, *state;
+ size_t l;
+ int r;
+ const char *property;
+
+ assert(u);
+ assert(dev);
+
+ property = u->manager->running_as == MANAGER_USER ? "SYSTEMD_USER_WANTS" : "SYSTEMD_WANTS";
+ wants = udev_device_get_property_value(dev, property);
+ if (!wants)
+ return 0;
+
+ FOREACH_WORD_QUOTED(word, l, wants, state) {
+ _cleanup_free_ char *n = NULL;
+ char e[l+1];
+
+ memcpy(e, word, l);
+ e[l] = 0;
+
+ r = unit_name_mangle(e, UNIT_NAME_NOGLOB, &n);
+ if (r < 0)
+ return log_unit_error_errno(u, r, "Failed to mangle unit name: %m");
+
+ r = unit_add_dependency_by_name(u, UNIT_WANTS, n, NULL, true);
+ if (r < 0)
+ return log_unit_error_errno(u, r, "Failed to add wants dependency: %m");
+ }
+ if (!isempty(state))
+ log_unit_warning(u, "Property %s on %s has trailing garbage, ignoring.", property, strna(udev_device_get_syspath(dev)));
+
+ return 0;
+}
+
+static int device_setup_unit(Manager *m, struct udev_device *dev, const char *path, bool main) {
+ _cleanup_free_ char *e = NULL;
+ const char *sysfs = NULL;
+ Unit *u = NULL;
+ bool delete;
+ int r;
+
+ assert(m);
+ assert(path);
+
+ if (dev) {
+ sysfs = udev_device_get_syspath(dev);
+ if (!sysfs)
+ return 0;
+ }
+
+ r = unit_name_from_path(path, ".device", &e);
+ if (r < 0)
+ return log_error_errno(r, "Failed to generate unit name from device path: %m");
+
+ u = manager_get_unit(m, e);
+
+ /* The device unit can still be present even if the device was
+ * unplugged: a mount unit can reference it hence preventing
+ * the GC to have garbaged it. That's desired since the device
+ * unit may have a dependency on the mount unit which was
+ * added during the loading of the later. */
+ if (u && DEVICE(u)->state == DEVICE_PLUGGED) {
+ /* This unit is in plugged state: we're sure it's
+ * attached to a device. */
+ if (!path_equal(DEVICE(u)->sysfs, sysfs)) {
+ log_unit_error(u, "Dev %s appeared twice with different sysfs paths %s and %s",
+ e, DEVICE(u)->sysfs, sysfs);
+ return -EEXIST;
+ }
+ }
+
+ if (!u) {
+ delete = true;
+
+ u = unit_new(m, sizeof(Device));
+ if (!u)
+ return log_oom();
+
+ r = unit_add_name(u, e);
+ if (r < 0)
+ goto fail;
+
+ unit_add_to_load_queue(u);
+ } else
+ delete = false;
+
+ /* If this was created via some dependency and has not
+ * actually been seen yet ->sysfs will not be
+ * initialized. Hence initialize it if necessary. */
+ if (sysfs) {
+ r = device_set_sysfs(DEVICE(u), sysfs);
+ if (r < 0)
+ goto fail;
+
+ (void) device_update_description(u, dev, path);
+
+ /* The additional systemd udev properties we only interpret
+ * for the main object */
+ if (main)
+ (void) device_add_udev_wants(u, dev);
+ }
+
+
+ /* Note that this won't dispatch the load queue, the caller
+ * has to do that if needed and appropriate */
+
+ unit_add_to_dbus_queue(u);
+ return 0;
+
+fail:
+ log_unit_warning_errno(u, r, "Failed to set up device unit: %m");
+
+ if (delete)
+ unit_free(u);
+
+ return r;
+}
+
+static int device_process_new(Manager *m, struct udev_device *dev) {
+ const char *sysfs, *dn, *alias;
+ struct udev_list_entry *item = NULL, *first = NULL;
+ int r;
+
+ assert(m);
+
+ sysfs = udev_device_get_syspath(dev);
+ if (!sysfs)
+ return 0;
+
+ /* Add the main unit named after the sysfs path */
+ r = device_setup_unit(m, dev, sysfs, true);
+ if (r < 0)
+ return r;
+
+ /* Add an additional unit for the device node */
+ dn = udev_device_get_devnode(dev);
+ if (dn)
+ (void) device_setup_unit(m, dev, dn, false);
+
+ /* Add additional units for all symlinks */
+ first = udev_device_get_devlinks_list_entry(dev);
+ udev_list_entry_foreach(item, first) {
+ const char *p;
+ struct stat st;
+
+ /* Don't bother with the /dev/block links */
+ p = udev_list_entry_get_name(item);
+
+ if (path_startswith(p, "/dev/block/") ||
+ path_startswith(p, "/dev/char/"))
+ continue;
+
+ /* Verify that the symlink in the FS actually belongs
+ * to this device. This is useful to deal with
+ * conflicting devices, e.g. when two disks want the
+ * same /dev/disk/by-label/xxx link because they have
+ * the same label. We want to make sure that the same
+ * device that won the symlink wins in systemd, so we
+ * check the device node major/minor */
+ if (stat(p, &st) >= 0)
+ if ((!S_ISBLK(st.st_mode) && !S_ISCHR(st.st_mode)) ||
+ st.st_rdev != udev_device_get_devnum(dev))
+ continue;
+
+ (void) device_setup_unit(m, dev, p, false);
+ }
+
+ /* Add additional units for all explicitly configured
+ * aliases */
+ alias = udev_device_get_property_value(dev, "SYSTEMD_ALIAS");
+ if (alias) {
+ const char *word, *state;
+ size_t l;
+
+ FOREACH_WORD_QUOTED(word, l, alias, state) {
+ char e[l+1];
+
+ memcpy(e, word, l);
+ e[l] = 0;
+
+ if (path_is_absolute(e))
+ (void) device_setup_unit(m, dev, e, false);
+ else
+ log_warning("SYSTEMD_ALIAS for %s is not an absolute path, ignoring: %s", sysfs, e);
+ }
+ if (!isempty(state))
+ log_warning("SYSTEMD_ALIAS for %s has trailing garbage, ignoring.", sysfs);
+ }
+
+ return 0;
+}
+
+static void device_update_found_one(Device *d, bool add, DeviceFound found, bool now) {
+ DeviceFound n, previous;
+
+ assert(d);
+
+ n = add ? (d->found | found) : (d->found & ~found);
+ if (n == d->found)
+ return;
+
+ previous = d->found;
+ d->found = n;
+
+ if (!now)
+ return;
+
+ if (d->found & DEVICE_FOUND_UDEV)
+ /* When the device is known to udev we consider it
+ * plugged. */
+ device_set_state(d, DEVICE_PLUGGED);
+ else if (d->found != DEVICE_NOT_FOUND && (previous & DEVICE_FOUND_UDEV) == 0)
+ /* If the device has not been seen by udev yet, but is
+ * now referenced by the kernel, then we assume the
+ * kernel knows it now, and udev might soon too. */
+ device_set_state(d, DEVICE_TENTATIVE);
+ else
+ /* If nobody sees the device, or if the device was
+ * previously seen by udev and now is only referenced
+ * from the kernel, then we consider the device is
+ * gone, the kernel just hasn't noticed it yet. */
+ device_set_state(d, DEVICE_DEAD);
+}
+
+static int device_update_found_by_sysfs(Manager *m, const char *sysfs, bool add, DeviceFound found, bool now) {
+ Device *d, *l;
+
+ assert(m);
+ assert(sysfs);
+
+ if (found == DEVICE_NOT_FOUND)
+ return 0;
+
+ l = hashmap_get(m->devices_by_sysfs, sysfs);
+ LIST_FOREACH(same_sysfs, d, l)
+ device_update_found_one(d, add, found, now);
+
+ return 0;
+}
+
+static int device_update_found_by_name(Manager *m, const char *path, bool add, DeviceFound found, bool now) {
+ _cleanup_free_ char *e = NULL;
+ Unit *u;
+ int r;
+
+ assert(m);
+ assert(path);
+
+ if (found == DEVICE_NOT_FOUND)
+ return 0;
+
+ r = unit_name_from_path(path, ".device", &e);
+ if (r < 0)
+ return log_error_errno(r, "Failed to generate unit name from device path: %m");
+
+ u = manager_get_unit(m, e);
+ if (!u)
+ return 0;
+
+ device_update_found_one(DEVICE(u), add, found, now);
+ return 0;
+}
+
+static bool device_is_ready(struct udev_device *dev) {
+ const char *ready;
+
+ assert(dev);
+
+ ready = udev_device_get_property_value(dev, "SYSTEMD_READY");
+ if (!ready)
+ return true;
+
+ return parse_boolean(ready) != 0;
+}
+
+static Unit *device_following(Unit *u) {
+ Device *d = DEVICE(u);
+ Device *other, *first = NULL;
+
+ assert(d);
+
+ if (startswith(u->id, "sys-"))
+ return NULL;
+
+ /* Make everybody follow the unit that's named after the sysfs path */
+ for (other = d->same_sysfs_next; other; other = other->same_sysfs_next)
+ if (startswith(UNIT(other)->id, "sys-"))
+ return UNIT(other);
+
+ for (other = d->same_sysfs_prev; other; other = other->same_sysfs_prev) {
+ if (startswith(UNIT(other)->id, "sys-"))
+ return UNIT(other);
+
+ first = other;
+ }
+
+ return UNIT(first);
+}
+
+static int device_following_set(Unit *u, Set **_set) {
+ Device *d = DEVICE(u), *other;
+ Set *set;
+ int r;
+
+ assert(d);
+ assert(_set);
+
+ if (LIST_JUST_US(same_sysfs, d)) {
+ *_set = NULL;
+ return 0;
+ }
+
+ set = set_new(NULL);
+ if (!set)
+ return -ENOMEM;
+
+ LIST_FOREACH_AFTER(same_sysfs, other, d) {
+ r = set_put(set, other);
+ if (r < 0)
+ goto fail;
+ }
+
+ LIST_FOREACH_BEFORE(same_sysfs, other, d) {
+ r = set_put(set, other);
+ if (r < 0)
+ goto fail;
+ }
+
+ *_set = set;
+ return 1;
+
+fail:
+ set_free(set);
+ return r;
+}
+
+static void device_shutdown(Manager *m) {
+ assert(m);
+
+ m->udev_event_source = sd_event_source_unref(m->udev_event_source);
+
+ if (m->udev_monitor) {
+ udev_monitor_unref(m->udev_monitor);
+ m->udev_monitor = NULL;
+ }
+
+ m->devices_by_sysfs = hashmap_free(m->devices_by_sysfs);
+}
+
+static void device_enumerate(Manager *m) {
+ _cleanup_udev_enumerate_unref_ struct udev_enumerate *e = NULL;
+ struct udev_list_entry *item = NULL, *first = NULL;
+ int r;
+
+ assert(m);
+
+ if (!m->udev_monitor) {
+ m->udev_monitor = udev_monitor_new_from_netlink(m->udev, "udev");
+ if (!m->udev_monitor) {
+ log_oom();
+ goto fail;
+ }
+
+ /* This will fail if we are unprivileged, but that
+ * should not matter much, as user instances won't run
+ * during boot. */
+ (void) udev_monitor_set_receive_buffer_size(m->udev_monitor, 128*1024*1024);
+
+ r = udev_monitor_filter_add_match_tag(m->udev_monitor, "systemd");
+ if (r < 0) {
+ log_error_errno(r, "Failed to add udev tag match: %m");
+ goto fail;
+ }
+
+ r = udev_monitor_enable_receiving(m->udev_monitor);
+ if (r < 0) {
+ log_error_errno(r, "Failed to enable udev event reception: %m");
+ goto fail;
+ }
+
+ r = sd_event_add_io(m->event, &m->udev_event_source, udev_monitor_get_fd(m->udev_monitor), EPOLLIN, device_dispatch_io, m);
+ if (r < 0) {
+ log_error_errno(r, "Failed to watch udev file descriptor: %m");
+ goto fail;
+ }
+
+ (void) sd_event_source_set_description(m->udev_event_source, "device");
+ }
+
+ e = udev_enumerate_new(m->udev);
+ if (!e) {
+ log_oom();
+ goto fail;
+ }
+
+ r = udev_enumerate_add_match_tag(e, "systemd");
+ if (r < 0) {
+ log_error_errno(r, "Failed to create udev tag enumeration: %m");
+ goto fail;
+ }
+
+ r = udev_enumerate_add_match_is_initialized(e);
+ if (r < 0) {
+ log_error_errno(r, "Failed to install initialization match into enumeration: %m");
+ goto fail;
+ }
+
+ r = udev_enumerate_scan_devices(e);
+ if (r < 0) {
+ log_error_errno(r, "Failed to enumerate devices: %m");
+ goto fail;
+ }
+
+ first = udev_enumerate_get_list_entry(e);
+ udev_list_entry_foreach(item, first) {
+ _cleanup_udev_device_unref_ struct udev_device *dev = NULL;
+ const char *sysfs;
+
+ sysfs = udev_list_entry_get_name(item);
+
+ dev = udev_device_new_from_syspath(m->udev, sysfs);
+ if (!dev) {
+ log_oom();
+ continue;
+ }
+
+ if (!device_is_ready(dev))
+ continue;
+
+ (void) device_process_new(m, dev);
+
+ device_update_found_by_sysfs(m, sysfs, true, DEVICE_FOUND_UDEV, false);
+ }
+
+ return;
+
+fail:
+ device_shutdown(m);
+}
+
+static int device_dispatch_io(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
+ _cleanup_udev_device_unref_ struct udev_device *dev = NULL;
+ Manager *m = userdata;
+ const char *action, *sysfs;
+ int r;
+
+ assert(m);
+
+ if (revents != EPOLLIN) {
+ static RATELIMIT_DEFINE(limit, 10*USEC_PER_SEC, 5);
+
+ if (!ratelimit_test(&limit))
+ log_error_errno(errno, "Failed to get udev event: %m");
+ if (!(revents & EPOLLIN))
+ return 0;
+ }
+
+ /*
+ * libudev might filter-out devices which pass the bloom
+ * filter, so getting NULL here is not necessarily an error.
+ */
+ dev = udev_monitor_receive_device(m->udev_monitor);
+ if (!dev)
+ return 0;
+
+ sysfs = udev_device_get_syspath(dev);
+ if (!sysfs) {
+ log_error("Failed to get udev sys path.");
+ return 0;
+ }
+
+ action = udev_device_get_action(dev);
+ if (!action) {
+ log_error("Failed to get udev action string.");
+ return 0;
+ }
+
+ if (streq(action, "remove")) {
+ r = swap_process_device_remove(m, dev);
+ if (r < 0)
+ log_error_errno(r, "Failed to process swap device remove event: %m");
+
+ /* If we get notified that a device was removed by
+ * udev, then it's completely gone, hence unset all
+ * found bits */
+ device_update_found_by_sysfs(m, sysfs, false, DEVICE_FOUND_UDEV|DEVICE_FOUND_MOUNT|DEVICE_FOUND_SWAP, true);
+
+ } else if (device_is_ready(dev)) {
+
+ (void) device_process_new(m, dev);
+
+ r = swap_process_device_new(m, dev);
+ if (r < 0)
+ log_error_errno(r, "Failed to process swap device new event: %m");
+
+ manager_dispatch_load_queue(m);
+
+ /* The device is found now, set the udev found bit */
+ device_update_found_by_sysfs(m, sysfs, true, DEVICE_FOUND_UDEV, true);
+
+ } else {
+ /* The device is nominally around, but not ready for
+ * us. Hence unset the udev bit, but leave the rest
+ * around. */
+
+ device_update_found_by_sysfs(m, sysfs, false, DEVICE_FOUND_UDEV, true);
+ }
+
+ return 0;
+}
+
+static bool device_supported(void) {
+ static int read_only = -1;
+
+ /* If /sys is read-only we don't support device units, and any
+ * attempts to start one should fail immediately. */
+
+ if (read_only < 0)
+ read_only = path_is_read_only_fs("/sys");
+
+ return read_only <= 0;
+}
+
+int device_found_node(Manager *m, const char *node, bool add, DeviceFound found, bool now) {
+ _cleanup_udev_device_unref_ struct udev_device *dev = NULL;
+ struct stat st;
+
+ assert(m);
+ assert(node);
+
+ if (!device_supported())
+ return 0;
+
+ /* This is called whenever we find a device referenced in
+ * /proc/swaps or /proc/self/mounts. Such a device might be
+ * mounted/enabled at a time where udev has not finished
+ * probing it yet, and we thus haven't learned about it
+ * yet. In this case we will set the device unit to
+ * "tentative" state. */
+
+ if (add) {
+ if (!path_startswith(node, "/dev"))
+ return 0;
+
+ /* We make an extra check here, if the device node
+ * actually exists. If it's missing, then this is an
+ * indication that device was unplugged but is still
+ * referenced in /proc/swaps or
+ * /proc/self/mountinfo. Note that this check doesn't
+ * really cover all cases where a device might be gone
+ * away, since drives that can have a medium inserted
+ * will still have a device node even when the medium
+ * is not there... */
+
+ if (stat(node, &st) >= 0) {
+ if (!S_ISBLK(st.st_mode) && !S_ISCHR(st.st_mode))
+ return 0;
+
+ dev = udev_device_new_from_devnum(m->udev, S_ISBLK(st.st_mode) ? 'b' : 'c', st.st_rdev);
+ if (!dev && errno != ENOENT)
+ return log_error_errno(errno, "Failed to get udev device from devnum %u:%u: %m", major(st.st_rdev), minor(st.st_rdev));
+
+ } else if (errno != ENOENT)
+ return log_error_errno(errno, "Failed to stat device node file %s: %m", node);
+
+ /* If the device is known in the kernel and newly
+ * appeared, then we'll create a device unit for it,
+ * under the name referenced in /proc/swaps or
+ * /proc/self/mountinfo. */
+
+ (void) device_setup_unit(m, dev, node, false);
+ }
+
+ /* Update the device unit's state, should it exist */
+ return device_update_found_by_name(m, node, add, found, now);
+}
+
+const UnitVTable device_vtable = {
+ .object_size = sizeof(Device),
+ .sections =
+ "Unit\0"
+ "Device\0"
+ "Install\0",
+
+ .no_instances = true,
+
+ .init = device_init,
+ .done = device_done,
+ .load = unit_load_fragment_and_dropin_optional,
+
+ .coldplug = device_coldplug,
+
+ .serialize = device_serialize,
+ .deserialize_item = device_deserialize_item,
+
+ .dump = device_dump,
+
+ .active_state = device_active_state,
+ .sub_state_to_string = device_sub_state_to_string,
+
+ .bus_vtable = bus_device_vtable,
+
+ .following = device_following,
+ .following_set = device_following_set,
+
+ .enumerate = device_enumerate,
+ .shutdown = device_shutdown,
+ .supported = device_supported,
+
+ .status_message_formats = {
+ .starting_stopping = {
+ [0] = "Expecting device %s...",
+ },
+ .finished_start_job = {
+ [JOB_DONE] = "Found device %s.",
+ [JOB_TIMEOUT] = "Timed out waiting for device %s.",
+ },
+ },
+};