[thirdparty/systemd.git] / src / udev / udevd.c

/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * Copyright © 2004 Chris Friesen <chris_friesen@sympatico.ca>
 * Copyright © 2009 Canonical Ltd.
 * Copyright © 2009 Scott James Remnant <scott@netsplit.com>
 */

#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <signal.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/file.h>
#include <sys/inotify.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/signalfd.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <unistd.h>

#include "sd-daemon.h"
#include "sd-event.h"

#include "alloc-util.h"
#include "build.h"
#include "cgroup-util.h"
#include "cpu-set-util.h"
#include "dev-setup.h"
#include "device-monitor-private.h"
#include "device-private.h"
#include "device-util.h"
#include "event-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "format-util.h"
#include "fs-util.h"
#include "hashmap.h"
#include "io-util.h"
#include "libudev-device-internal.h"
#include "list.h"
#include "main-func.h"
#include "mkdir.h"
#include "netlink-util.h"
#include "parse-util.h"
#include "pretty-print.h"
#include "proc-cmdline.h"
#include "process-util.h"
#include "selinux-util.h"
#include "signal-util.h"
#include "socket-util.h"
#include "string-util.h"
#include "strv.h"
#include "strxcpyx.h"
#include "syslog-util.h"
#include "udev-builtin.h"
#include "udev-ctrl.h"
#include "udev-util.h"
#include "udev-watch.h"
#include "udev.h"
#include "user-util.h"

static bool arg_debug = false;
static int arg_daemonize = false;
static ResolveNameTiming arg_resolve_name_timing = RESOLVE_NAME_EARLY;
static unsigned arg_children_max = 0;
static usec_t arg_exec_delay_usec = 0;
static usec_t arg_event_timeout_usec = 180 * USEC_PER_SEC;

typedef struct Manager {
        sd_event *event;
        Hashmap *workers;
        LIST_HEAD(struct event, events);
        const char *cgroup;
        pid_t pid; /* the process that originally allocated the manager object */

        UdevRules *rules;
        Hashmap *properties;

        sd_netlink *rtnl;

        sd_device_monitor *monitor;
        struct udev_ctrl *ctrl;
        struct udev_ctrl_connection *ctrl_conn_blocking;
        int fd_inotify;
        int worker_watch[2];

        sd_event_source *ctrl_event;
        sd_event_source *uevent_event;
        sd_event_source *inotify_event;
        sd_event_source *kill_workers_event;

        usec_t last_usec;

        bool stop_exec_queue:1;
        bool exit:1;
} Manager;

enum event_state {
        EVENT_UNDEF,
        EVENT_QUEUED,
        EVENT_RUNNING,
};

struct event {
        Manager *manager;
        struct worker *worker;
        enum event_state state;

        sd_device *dev;
        sd_device *dev_kernel; /* clone of originally received device */

        uint64_t seqnum;
        uint64_t delaying_seqnum;

        sd_event_source *timeout_warning_event;
        sd_event_source *timeout_event;

        LIST_FIELDS(struct event, event);
};

static void event_queue_cleanup(Manager *manager, enum event_state type);

enum worker_state {
        WORKER_UNDEF,
        WORKER_RUNNING,
        WORKER_IDLE,
        WORKER_KILLED,
};

struct worker {
        Manager *manager;
        pid_t pid;
        sd_device_monitor *monitor;
        enum worker_state state;
        struct event *event;
};

/* passed from worker to main process */
struct worker_message {
};

static void event_free(struct event *event) {
        if (!event)
                return;

        assert(event->manager);

        LIST_REMOVE(event, event->manager->events, event);
        sd_device_unref(event->dev);
        sd_device_unref(event->dev_kernel);

        sd_event_source_unref(event->timeout_warning_event);
        sd_event_source_unref(event->timeout_event);

        if (event->worker)
                event->worker->event = NULL;

        /* only clean up the queue from the process that created it */
        if (LIST_IS_EMPTY(event->manager->events) &&
            event->manager->pid == getpid_cached())
                if (unlink("/run/udev/queue") < 0)
                        log_warning_errno(errno, "Failed to unlink /run/udev/queue: %m");

        free(event);
}

static void worker_free(struct worker *worker) {
        if (!worker)
                return;

        assert(worker->manager);

        hashmap_remove(worker->manager->workers, PID_TO_PTR(worker->pid));
        sd_device_monitor_unref(worker->monitor);
        event_free(worker->event);

        free(worker);
}

static void manager_workers_free(Manager *manager) {
        struct worker *worker;
        Iterator i;

        assert(manager);

        HASHMAP_FOREACH(worker, manager->workers, i)
                worker_free(worker);

        manager->workers = hashmap_free(manager->workers);
}

static int worker_new(struct worker **ret, Manager *manager, sd_device_monitor *worker_monitor, pid_t pid) {
        _cleanup_free_ struct worker *worker = NULL;
        int r;

        assert(ret);
        assert(manager);
        assert(worker_monitor);
        assert(pid > 1);

        worker = new0(struct worker, 1);
        if (!worker)
                return -ENOMEM;

        worker->manager = manager;
        /* close monitor, but keep address around */
        device_monitor_disconnect(worker_monitor);
        worker->monitor = sd_device_monitor_ref(worker_monitor);
        worker->pid = pid;

        r = hashmap_ensure_allocated(&manager->workers, NULL);
        if (r < 0)
                return r;

        r = hashmap_put(manager->workers, PID_TO_PTR(pid), worker);
        if (r < 0)
                return r;

        *ret = TAKE_PTR(worker);

        return 0;
}

static int on_event_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
        struct event *event = userdata;

        assert(event);
        assert(event->worker);

        kill_and_sigcont(event->worker->pid, SIGKILL);
        event->worker->state = WORKER_KILLED;

        log_device_error(event->dev, "Worker ["PID_FMT"] processing SEQNUM=%"PRIu64" killed", event->worker->pid, event->seqnum);

        return 1;
}

static int on_event_timeout_warning(sd_event_source *s, uint64_t usec, void *userdata) {
        struct event *event = userdata;

        assert(event);
        assert(event->worker);

        log_device_warning(event->dev, "Worker ["PID_FMT"] processing SEQNUM=%"PRIu64" is taking a long time", event->worker->pid, event->seqnum);

        return 1;
}

static void worker_attach_event(struct worker *worker, struct event *event) {
        sd_event *e;
        uint64_t usec;

        assert(worker);
        assert(worker->manager);
        assert(event);
        assert(!event->worker);
        assert(!worker->event);

        worker->state = WORKER_RUNNING;
        worker->event = event;
        event->state = EVENT_RUNNING;
        event->worker = worker;

        e = worker->manager->event;

        assert_se(sd_event_now(e, CLOCK_MONOTONIC, &usec) >= 0);

        (void) sd_event_add_time(e, &event->timeout_warning_event, CLOCK_MONOTONIC,
                                 usec + udev_warn_timeout(arg_event_timeout_usec), USEC_PER_SEC, on_event_timeout_warning, event);

        (void) sd_event_add_time(e, &event->timeout_event, CLOCK_MONOTONIC,
                                 usec + arg_event_timeout_usec, USEC_PER_SEC, on_event_timeout, event);
}

static void manager_clear_for_worker(Manager *manager) {
        assert(manager);

        manager->ctrl_event = sd_event_source_unref(manager->ctrl_event);
        manager->uevent_event = sd_event_source_unref(manager->uevent_event);
        manager->inotify_event = sd_event_source_unref(manager->inotify_event);
        manager->kill_workers_event = sd_event_source_unref(manager->kill_workers_event);

        manager->event = sd_event_unref(manager->event);

        manager_workers_free(manager);
        event_queue_cleanup(manager, EVENT_UNDEF);

        manager->monitor = sd_device_monitor_unref(manager->monitor);
        manager->ctrl_conn_blocking = udev_ctrl_connection_unref(manager->ctrl_conn_blocking);
        manager->ctrl = udev_ctrl_unref(manager->ctrl);

        manager->worker_watch[READ_END] = safe_close(manager->worker_watch[READ_END]);
}

static void manager_free(Manager *manager) {
        if (!manager)
                return;

        udev_builtin_exit();

        manager_clear_for_worker(manager);

        sd_netlink_unref(manager->rtnl);

        hashmap_free_free_free(manager->properties);
        udev_rules_free(manager->rules);

        safe_close(manager->fd_inotify);
        safe_close_pair(manager->worker_watch);

        free(manager);
}

DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_free);

static int worker_send_message(int fd) {
        struct worker_message message = {};

        return loop_write(fd, &message, sizeof(message), false);
}

static int worker_lock_block_device(sd_device *dev, int *ret_fd) {
        _cleanup_close_ int fd = -1;
        const char *val;
        int r;

        assert(dev);
        assert(ret_fd);

        /*
         * Take a shared lock on the device node; this establishes
         * a concept of device "ownership" to serialize device
         * access. External processes holding an exclusive lock will
         * cause udev to skip the event handling; in the case udev
         * acquired the lock, the external process can block until
         * udev has finished its event handling.
         */

        r = sd_device_get_property_value(dev, "ACTION", &val);
        if (r < 0)
                return log_device_debug_errno(dev, r, "Failed to get the value of property 'ACTION': %m");

        if (streq(val, "remove"))
                return 0;

        r = sd_device_get_subsystem(dev, &val);
        if (r < 0)
                return log_device_debug_errno(dev, r, "Failed to get subsystem: %m");

        if (!streq(val, "block"))
                return 0;

        r = sd_device_get_sysname(dev, &val);
        if (r < 0)
                return log_device_debug_errno(dev, r, "Failed to get sysname: %m");

        if (STARTSWITH_SET(val, "dm-", "md", "drbd"))
                return 0;

        r = sd_device_get_devtype(dev, &val);
        if (r < 0 && r != -ENOENT)
                return log_device_debug_errno(dev, r, "Failed to get devtype: %m");
        if (r >= 0 && streq(val, "partition")) {
                r = sd_device_get_parent(dev, &dev);
                if (r < 0)
                        return log_device_debug_errno(dev, r, "Failed to get parent device: %m");
        }

        r = sd_device_get_devname(dev, &val);
        if (r == -ENOENT)
                return 0;
        if (r < 0)
                return log_device_debug_errno(dev, r, "Failed to get devname: %m");

        fd = open(val, O_RDONLY|O_CLOEXEC|O_NOFOLLOW|O_NONBLOCK);
        if (fd < 0) {
                log_device_debug_errno(dev, errno, "Failed to open '%s', ignoring: %m", val);
                return 0;
        }

        if (flock(fd, LOCK_SH|LOCK_NB) < 0)
                return log_device_debug_errno(dev, errno, "Failed to flock(%s): %m", val);

        *ret_fd = TAKE_FD(fd);
        return 1;
}

static int worker_process_device(Manager *manager, sd_device *dev) {
        _cleanup_(udev_event_freep) UdevEvent *udev_event = NULL;
        _cleanup_close_ int fd_lock = -1;
        const char *seqnum;
        int r;

        assert(manager);
        assert(dev);

        r = sd_device_get_property_value(dev, "SEQNUM", &seqnum);
        if (r < 0)
                log_device_debug_errno(dev, r, "Failed to get SEQNUM: %m");

        log_device_debug(dev, "Processing device (SEQNUM=%s)", seqnum);

        udev_event = udev_event_new(dev, arg_exec_delay_usec, manager->rtnl);
        if (!udev_event)
                return -ENOMEM;

        r = worker_lock_block_device(dev, &fd_lock);
        if (r < 0)
                return r;

        /* apply rules, create node, symlinks */
        udev_event_execute_rules(udev_event, arg_event_timeout_usec, manager->properties, manager->rules);
        udev_event_execute_run(udev_event, arg_event_timeout_usec);

        if (!manager->rtnl)
                /* in case rtnl was initialized */
                manager->rtnl = sd_netlink_ref(udev_event->rtnl);

        /* apply/restore inotify watch */
        if (udev_event->inotify_watch) {
                (void) udev_watch_begin(dev);
                r = device_update_db(dev);
                if (r < 0)
                        return log_device_debug_errno(dev, r, "Failed to update database under /run/udev/data/: %m");
        }

        log_device_debug(dev, "Device (SEQNUM=%s) processed", seqnum);

        return 0;
}

static int worker_device_monitor_handler(sd_device_monitor *monitor, sd_device *dev, void *userdata) {
        Manager *manager = userdata;
        int r;

        assert(dev);
        assert(manager);

        r = worker_process_device(manager, dev);
        if (r < 0)
                log_device_warning_errno(dev, r, "Failed to process device, ignoring: %m");

        /* send processed event back to libudev listeners */
        r = device_monitor_send_device(monitor, NULL, dev);
        if (r < 0)
                log_device_warning_errno(dev, r, "Failed to send device, ignoring: %m");

        /* send udevd the result of the event execution */
        r = worker_send_message(manager->worker_watch[WRITE_END]);
        if (r < 0)
                log_device_warning_errno(dev, r, "Failed to send signal to main daemon, ignoring: %m");

        return 1;
}

static int worker_main(Manager *_manager, sd_device_monitor *monitor, sd_device *first_device) {
        _cleanup_(sd_device_unrefp) sd_device *dev = first_device;
        _cleanup_(manager_freep) Manager *manager = _manager;
        int r, ret;

        assert(manager);
        assert(monitor);
        assert(dev);

        unsetenv("NOTIFY_SOCKET");

        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, -1) >= 0);

        /* Reset OOM score, we only protect the main daemon. */
        r = set_oom_score_adjust(0);
        if (r < 0)
                log_debug_errno(r, "Failed to reset OOM score, ignoring: %m");

        /* Clear unnecessary data in Manager object.*/
        manager_clear_for_worker(manager);

        r = sd_event_new(&manager->event);
        if (r < 0)
                return log_error_errno(r, "Failed to allocate event loop: %m");

        r = sd_event_add_signal(manager->event, NULL, SIGTERM, NULL, NULL);
        if (r < 0)
                return log_error_errno(r, "Failed to set SIGTERM event: %m");

        r = sd_device_monitor_attach_event(monitor, manager->event);
        if (r < 0)
                return log_error_errno(r, "Failed to attach event loop to device monitor: %m");

        r = sd_device_monitor_start(monitor, worker_device_monitor_handler, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to start device monitor: %m");

        (void) sd_event_source_set_description(sd_device_monitor_get_event_source(monitor), "worker-device-monitor");

        /* Process first device */
        (void) worker_device_monitor_handler(monitor, dev, manager);

        r = sd_event_loop(manager->event);
        if (r < 0)
                return log_error_errno(r, "Event loop failed: %m");

        r = sd_event_get_exit_code(manager->event, &ret);
        if (r < 0)
                return log_error_errno(r, "Failed to get exit code: %m");

        return ret;
}

static int worker_spawn(Manager *manager, struct event *event) {
        _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *worker_monitor = NULL;
        struct worker *worker;
        pid_t pid;
        int r;

        /* listen for new events */
        r = device_monitor_new_full(&worker_monitor, MONITOR_GROUP_NONE, -1);
        if (r < 0)
                return r;

        /* allow the main daemon netlink address to send devices to the worker */
        r = device_monitor_allow_unicast_sender(worker_monitor, manager->monitor);
        if (r < 0)
                return log_error_errno(r, "Worker: Failed to set unicast sender: %m");

        r = device_monitor_enable_receiving(worker_monitor);
        if (r < 0)
                return log_error_errno(r, "Worker: Failed to enable receiving of device: %m");

        r = safe_fork(NULL, FORK_DEATHSIG, &pid);
        if (r < 0) {
                event->state = EVENT_QUEUED;
                return log_error_errno(r, "Failed to fork() worker: %m");
        }
        if (r == 0) {
                /* Worker process */
                r = worker_main(manager, worker_monitor, sd_device_ref(event->dev));
                log_close();
                _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
        }

        r = worker_new(&worker, manager, worker_monitor, pid);
        if (r < 0)
                return log_error_errno(r, "Failed to create worker object: %m");

        worker_attach_event(worker, event);

        log_device_debug(event->dev, "Worker ["PID_FMT"] is forked for processing SEQNUM=%"PRIu64".", pid, event->seqnum);
        return 0;
}

static void event_run(Manager *manager, struct event *event) {
        struct worker *worker;
        Iterator i;
        int r;

        assert(manager);
        assert(event);

        HASHMAP_FOREACH(worker, manager->workers, i) {
                if (worker->state != WORKER_IDLE)
                        continue;

                r = device_monitor_send_device(manager->monitor, worker->monitor, event->dev);
                if (r < 0) {
                        log_device_error_errno(event->dev, r, "Worker ["PID_FMT"] did not accept message, killing the worker: %m",
                                               worker->pid);
                        (void) kill(worker->pid, SIGKILL);
                        worker->state = WORKER_KILLED;
                        continue;
                }
                worker_attach_event(worker, event);
                return;
        }

        if (hashmap_size(manager->workers) >= arg_children_max) {
                if (arg_children_max > 1)
                        log_debug("Maximum number (%u) of children reached.", hashmap_size(manager->workers));
                return;
        }

        /* start new worker and pass initial device */
        worker_spawn(manager, event);
}

static int event_queue_insert(Manager *manager, sd_device *dev) {
        _cleanup_(sd_device_unrefp) sd_device *clone = NULL;
        struct event *event;
        const char *val;
        uint64_t seqnum;
        int r;

        assert(manager);
        assert(dev);

        /* only one process can add events to the queue */
        if (manager->pid == 0)
                manager->pid = getpid_cached();

        assert(manager->pid == getpid_cached());

        /* We only accepts devices received by device monitor. */
        r = sd_device_get_property_value(dev, "SEQNUM", &val);
        if (r < 0)
                return r;

        r = safe_atou64(val, &seqnum);
        if (r < 0)
                return r;

        if (seqnum == 0)
                return -EINVAL;

        /* Save original device to restore the state on failures. */
        r = device_shallow_clone(dev, &clone);
        if (r < 0)
                return r;

        r = device_copy_properties(clone, dev);
        if (r < 0)
                return r;

        event = new(struct event, 1);
        if (!event)
                return -ENOMEM;

        *event = (struct event) {
                .manager = manager,
                .dev = sd_device_ref(dev),
                .dev_kernel = TAKE_PTR(clone),
                .seqnum = seqnum,
                .state = EVENT_QUEUED,
        };

        if (LIST_IS_EMPTY(manager->events)) {
                r = touch("/run/udev/queue");
                if (r < 0)
                        log_warning_errno(r, "Failed to touch /run/udev/queue: %m");
        }

        LIST_APPEND(event, manager->events, event);

        if (DEBUG_LOGGING) {
                if (sd_device_get_property_value(dev, "ACTION", &val) < 0)
                        val = NULL;

                log_device_debug(dev, "Device (SEQNUM=%"PRIu64", ACTION=%s) is queued", seqnum, strnull(val));
        }

        return 0;
}

static void manager_kill_workers(Manager *manager) {
        struct worker *worker;
        Iterator i;

        assert(manager);

        HASHMAP_FOREACH(worker, manager->workers, i) {
                if (worker->state == WORKER_KILLED)
                        continue;

                worker->state = WORKER_KILLED;
                (void) kill(worker->pid, SIGTERM);
        }
}

/* lookup event for identical, parent, child device */
static int is_device_busy(Manager *manager, struct event *event) {
        const char *subsystem, *devpath, *devpath_old = NULL;
        dev_t devnum = makedev(0, 0);
        struct event *loop_event;
        size_t devpath_len;
        int r, ifindex = 0;
        bool is_block;

        r = sd_device_get_subsystem(event->dev, &subsystem);
        if (r < 0)
                return r;

        is_block = streq(subsystem, "block");

        r = sd_device_get_devpath(event->dev, &devpath);
        if (r < 0)
                return r;

        devpath_len = strlen(devpath);

        r = sd_device_get_property_value(event->dev, "DEVPATH_OLD", &devpath_old);
        if (r < 0 && r != -ENOENT)
                return r;

        r = sd_device_get_devnum(event->dev, &devnum);
        if (r < 0 && r != -ENOENT)
                return r;

        r = sd_device_get_ifindex(event->dev, &ifindex);
        if (r < 0 && r != -ENOENT)
                return r;

        /* check if queue contains events we depend on */
        LIST_FOREACH(event, loop_event, manager->events) {
                size_t loop_devpath_len, common;
                const char *loop_devpath;

                /* we already found a later event, earlier cannot block us, no need to check again */
                if (loop_event->seqnum < event->delaying_seqnum)
                        continue;

                /* event we checked earlier still exists, no need to check again */
                if (loop_event->seqnum == event->delaying_seqnum)
                        return true;

                /* found ourself, no later event can block us */
                if (loop_event->seqnum >= event->seqnum)
                        break;

                /* check major/minor */
                if (major(devnum) != 0) {
                        const char *s;
                        dev_t d;

                        if (sd_device_get_subsystem(loop_event->dev, &s) < 0)
                                continue;

                        if (sd_device_get_devnum(loop_event->dev, &d) >= 0 &&
                            devnum == d && is_block == streq(s, "block"))
                                return true;
                }

                /* check network device ifindex */
                if (ifindex > 0) {
                        int i;

                        if (sd_device_get_ifindex(loop_event->dev, &i) >= 0 &&
                            ifindex == i)
                                return true;
                }

                if (sd_device_get_devpath(loop_event->dev, &loop_devpath) < 0)
                        continue;

                /* check our old name */
                if (devpath_old && streq(devpath_old, loop_devpath)) {
                        event->delaying_seqnum = loop_event->seqnum;
                        return true;
                }

                loop_devpath_len = strlen(loop_devpath);

                /* compare devpath */
                common = MIN(devpath_len, loop_devpath_len);

                /* one devpath is contained in the other? */
                if (!strneq(devpath, loop_devpath, common))
                        continue;

                /* identical device event found */
                if (devpath_len == loop_devpath_len) {
                        /* devices names might have changed/swapped in the meantime */
                        if (major(devnum) != 0 || ifindex > 0)
                                continue;
                        event->delaying_seqnum = loop_event->seqnum;
                        return true;
                }

                /* parent device event found */
                if (devpath[common] == '/') {
                        event->delaying_seqnum = loop_event->seqnum;
                        return true;
                }

                /* child device event found */
                if (loop_devpath[common] == '/') {
                        event->delaying_seqnum = loop_event->seqnum;
                        return true;
                }
        }

        return false;
}

static int on_exit_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
        Manager *manager = userdata;

        assert(manager);

        log_error("Giving up waiting for workers to finish.");
        sd_event_exit(manager->event, -ETIMEDOUT);

        return 1;
}

static void manager_exit(Manager *manager) {
        uint64_t usec;
        int r;

        assert(manager);

        manager->exit = true;

        sd_notify(false,
                  "STOPPING=1\n"
                  "STATUS=Starting shutdown...");

        /* close sources of new events and discard buffered events */
        manager->ctrl_event = sd_event_source_unref(manager->ctrl_event);
        manager->ctrl = udev_ctrl_unref(manager->ctrl);

        manager->inotify_event = sd_event_source_unref(manager->inotify_event);
        manager->fd_inotify = safe_close(manager->fd_inotify);

        manager->uevent_event = sd_event_source_unref(manager->uevent_event);
        manager->monitor = sd_device_monitor_unref(manager->monitor);

        /* discard queued events and kill workers */
        event_queue_cleanup(manager, EVENT_QUEUED);
        manager_kill_workers(manager);

        assert_se(sd_event_now(manager->event, CLOCK_MONOTONIC, &usec) >= 0);

        r = sd_event_add_time(manager->event, NULL, CLOCK_MONOTONIC,
                              usec + 30 * USEC_PER_SEC, USEC_PER_SEC, on_exit_timeout, manager);
        if (r < 0)
                return;
}

/* reload requested, HUP signal received, rules changed, builtin changed */
static void manager_reload(Manager *manager) {

        assert(manager);

        sd_notify(false,
                  "RELOADING=1\n"
                  "STATUS=Flushing configuration...");

        manager_kill_workers(manager);
        manager->rules = udev_rules_free(manager->rules);
        udev_builtin_exit();

        sd_notifyf(false,
                   "READY=1\n"
                   "STATUS=Processing with %u children at max", arg_children_max);
}

static int on_kill_workers_event(sd_event_source *s, uint64_t usec, void *userdata) {
        Manager *manager = userdata;

        assert(manager);

        log_debug("Cleanup idle workers");
        manager_kill_workers(manager);

        return 1;
}

static void event_queue_start(Manager *manager) {
        struct event *event;
        usec_t usec;
        int r;

        assert(manager);

        if (LIST_IS_EMPTY(manager->events) ||
            manager->exit || manager->stop_exec_queue)
                return;

        assert_se(sd_event_now(manager->event, CLOCK_MONOTONIC, &usec) >= 0);
        /* check for changed config, every 3 seconds at most */
        if (manager->last_usec == 0 ||
            (usec - manager->last_usec) > 3 * USEC_PER_SEC) {
                if (udev_rules_check_timestamp(manager->rules) ||
                    udev_builtin_validate())
                        manager_reload(manager);

                manager->last_usec = usec;
        }

        r = event_source_disable(manager->kill_workers_event);
        if (r < 0)
                log_warning_errno(r, "Failed to disable event source for cleaning up idle workers, ignoring: %m");

        udev_builtin_init();

        if (!manager->rules) {
                r = udev_rules_new(&manager->rules, arg_resolve_name_timing);
                if (r < 0) {
                        log_warning_errno(r, "Failed to read udev rules: %m");
                        return;
                }
        }

        LIST_FOREACH(event, event, manager->events) {
                if (event->state != EVENT_QUEUED)
                        continue;

                /* do not start event if parent or child event is still running */
                if (is_device_busy(manager, event) != 0)
                        continue;

                event_run(manager, event);
        }
}

static void event_queue_cleanup(Manager *manager, enum event_state match_type) {
        struct event *event, *tmp;

        LIST_FOREACH_SAFE(event, event, tmp, manager->events) {
                if (match_type != EVENT_UNDEF && match_type != event->state)
                        continue;

                event_free(event);
        }
}

static int on_worker(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
        Manager *manager = userdata;

        assert(manager);

        for (;;) {
                struct worker_message msg;
                struct iovec iovec = {
                        .iov_base = &msg,
                        .iov_len = sizeof(msg),
                };
                union {
                        struct cmsghdr cmsghdr;
                        uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
                } control = {};
                struct msghdr msghdr = {
                        .msg_iov = &iovec,
                        .msg_iovlen = 1,
                        .msg_control = &control,
                        .msg_controllen = sizeof(control),
                };
                struct cmsghdr *cmsg;
                ssize_t size;
                struct ucred *ucred = NULL;
                struct worker *worker;

                size = recvmsg(fd, &msghdr, MSG_DONTWAIT);
                if (size < 0) {
                        if (errno == EINTR)
                                continue;
                        else if (errno == EAGAIN)
                                /* nothing more to read */
                                break;

                        return log_error_errno(errno, "Failed to receive message: %m");
                } else if (size != sizeof(struct worker_message)) {
                        log_warning("Ignoring worker message with invalid size %zi bytes", size);
                        continue;
                }

                CMSG_FOREACH(cmsg, &msghdr) {
                        if (cmsg->cmsg_level == SOL_SOCKET &&
                            cmsg->cmsg_type == SCM_CREDENTIALS &&
                            cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)))
                                ucred = (struct ucred*) CMSG_DATA(cmsg);
                }

                if (!ucred || ucred->pid <= 0) {
                        log_warning("Ignoring worker message without valid PID");
                        continue;
                }

                /* lookup worker who sent the signal */
                worker = hashmap_get(manager->workers, PID_TO_PTR(ucred->pid));
                if (!worker) {
                        log_debug("Worker ["PID_FMT"] returned, but is no longer tracked", ucred->pid);
                        continue;
                }

                if (worker->state != WORKER_KILLED)
                        worker->state = WORKER_IDLE;

                /* worker returned */
                event_free(worker->event);
        }

        /* we have free workers, try to schedule events */
        event_queue_start(manager);

        return 1;
}

static int on_uevent(sd_device_monitor *monitor, sd_device *dev, void *userdata) {
        Manager *manager = userdata;
        int r;

        assert(manager);

        device_ensure_usec_initialized(dev, NULL);

        r = event_queue_insert(manager, dev);
        if (r < 0) {
                log_device_error_errno(dev, r, "Failed to insert device into event queue: %m");
                return 1;
        }

        /* we have fresh events, try to schedule them */
        event_queue_start(manager);

        return 1;
}

/* receive the udevd message from userspace */
static int on_ctrl_msg(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
        Manager *manager = userdata;
        _cleanup_(udev_ctrl_connection_unrefp) struct udev_ctrl_connection *ctrl_conn = NULL;
        _cleanup_(udev_ctrl_msg_unrefp) struct udev_ctrl_msg *ctrl_msg = NULL;
        const char *str;
        int i, r;

        assert(manager);

        ctrl_conn = udev_ctrl_get_connection(manager->ctrl);
        if (!ctrl_conn)
                return 1;

        ctrl_msg = udev_ctrl_receive_msg(ctrl_conn);
        if (!ctrl_msg)
                return 1;

        i = udev_ctrl_get_set_log_level(ctrl_msg);
        if (i >= 0) {
                log_debug("Received udev control message (SET_LOG_LEVEL), setting log_priority=%i", i);
                log_set_max_level(i);
                manager_kill_workers(manager);
        }

        if (udev_ctrl_get_stop_exec_queue(ctrl_msg) > 0) {
                log_debug("Received udev control message (STOP_EXEC_QUEUE)");
                manager->stop_exec_queue = true;
        }

        if (udev_ctrl_get_start_exec_queue(ctrl_msg) > 0) {
                log_debug("Received udev control message (START_EXEC_QUEUE)");
                manager->stop_exec_queue = false;
                event_queue_start(manager);
        }

        if (udev_ctrl_get_reload(ctrl_msg) > 0) {
                log_debug("Received udev control message (RELOAD)");
                manager_reload(manager);
        }

        str = udev_ctrl_get_set_env(ctrl_msg);
        if (str) {
                _cleanup_free_ char *key = NULL, *val = NULL, *old_key = NULL, *old_val = NULL;
                char *eq;

                eq = strchr(str, '=');
                if (!eq) {
                        log_error("Invalid key format '%s'", str);
                        return 1;
                }

                key = strndup(str, eq - str);
                if (!key) {
                        log_oom();
                        return 1;
                }

                old_val = hashmap_remove2(manager->properties, key, (void **) &old_key);

                r = hashmap_ensure_allocated(&manager->properties, &string_hash_ops);
                if (r < 0) {
                        log_oom();
                        return 1;
                }

                eq++;
                if (!isempty(eq)) {
                        log_debug("Received udev control message (ENV), unsetting '%s'", key);

                        r = hashmap_put(manager->properties, key, NULL);
                        if (r < 0) {
                                log_oom();
                                return 1;
                        }
                } else {
                        val = strdup(eq);
                        if (!val) {
                                log_oom();
                                return 1;
                        }

                        log_debug("Received udev control message (ENV), setting '%s=%s'", key, val);

                        r = hashmap_put(manager->properties, key, val);
                        if (r < 0) {
                                log_oom();
                                return 1;
                        }
                }

                key = val = NULL;
                manager_kill_workers(manager);
        }

        i = udev_ctrl_get_set_children_max(ctrl_msg);
        if (i >= 0) {
                log_debug("Receivd udev control message (SET_MAX_CHILDREN), setting children_max=%i", i);
                arg_children_max = i;

                (void) sd_notifyf(false,
                                  "READY=1\n"
                                  "STATUS=Processing with %u children at max", arg_children_max);
        }

        if (udev_ctrl_get_ping(ctrl_msg) > 0)
                log_debug("Received udev control message (SYNC)");

        if (udev_ctrl_get_exit(ctrl_msg) > 0) {
                log_debug("Received udev control message (EXIT)");
                manager_exit(manager);
                /* keep reference to block the client until we exit
                   TODO: deal with several blocking exit requests */
                manager->ctrl_conn_blocking = udev_ctrl_connection_ref(ctrl_conn);
        }

        return 1;
}

static int synthesize_change(sd_device *dev) {
        const char *subsystem, *sysname, *devname, *syspath, *devtype;
        char filename[PATH_MAX];
        int r;

        r = sd_device_get_subsystem(dev, &subsystem);
        if (r < 0)
                return r;

        r = sd_device_get_sysname(dev, &sysname);
        if (r < 0)
                return r;

        r = sd_device_get_devname(dev, &devname);
        if (r < 0)
                return r;

        r = sd_device_get_syspath(dev, &syspath);
        if (r < 0)
                return r;

        r = sd_device_get_devtype(dev, &devtype);
        if (r < 0)
                return r;

        if (streq_ptr("block", subsystem) &&
            streq_ptr("disk", devtype) &&
            !startswith(sysname, "dm-")) {
                _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
                bool part_table_read = false, has_partitions = false;
                sd_device *d;
                int fd;

                /*
                 * Try to re-read the partition table. This only succeeds if
                 * none of the devices is busy. The kernel returns 0 if no
                 * partition table is found, and we will not get an event for
                 * the disk.
                 */
                fd = open(devname, O_RDONLY|O_CLOEXEC|O_NOFOLLOW|O_NONBLOCK);
                if (fd >= 0) {
                        r = flock(fd, LOCK_EX|LOCK_NB);
                        if (r >= 0)
                                r = ioctl(fd, BLKRRPART, 0);

                        close(fd);
                        if (r >= 0)
                                part_table_read = true;
                }

                /* search for partitions */
                r = sd_device_enumerator_new(&e);
                if (r < 0)
                        return r;

                r = sd_device_enumerator_allow_uninitialized(e);
                if (r < 0)
                        return r;

                r = sd_device_enumerator_add_match_parent(e, dev);
                if (r < 0)
                        return r;

                r = sd_device_enumerator_add_match_subsystem(e, "block", true);
                if (r < 0)
                        return r;

                FOREACH_DEVICE(e, d) {
                        const char *t;

                        if (sd_device_get_devtype(d, &t) < 0 ||
                            !streq("partition", t))
                                continue;

                        has_partitions = true;
                        break;
                }

                /*
                 * We have partitions and re-read the table, the kernel already sent
                 * out a "change" event for the disk, and "remove/add" for all
                 * partitions.
                 */
                if (part_table_read && has_partitions)
                        return 0;

                /*
                 * We have partitions but re-reading the partition table did not
                 * work, synthesize "change" for the disk and all partitions.
                 */
                log_debug("Device '%s' is closed, synthesising 'change'", devname);
                strscpyl(filename, sizeof(filename), syspath, "/uevent", NULL);
                write_string_file(filename, "change", WRITE_STRING_FILE_DISABLE_BUFFER);

                FOREACH_DEVICE(e, d) {
                        const char *t, *n, *s;

                        if (sd_device_get_devtype(d, &t) < 0 ||
                            !streq("partition", t))
                                continue;

                        if (sd_device_get_devname(d, &n) < 0 ||
                            sd_device_get_syspath(d, &s) < 0)
                                continue;

                        log_debug("Device '%s' is closed, synthesising partition '%s' 'change'", devname, n);
                        strscpyl(filename, sizeof(filename), s, "/uevent", NULL);
                        write_string_file(filename, "change", WRITE_STRING_FILE_DISABLE_BUFFER);
                }

                return 0;
        }

        log_debug("Device %s is closed, synthesising 'change'", devname);
        strscpyl(filename, sizeof(filename), syspath, "/uevent", NULL);
        write_string_file(filename, "change", WRITE_STRING_FILE_DISABLE_BUFFER);

        return 0;
}

static int on_inotify(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
        Manager *manager = userdata;
        union inotify_event_buffer buffer;
        struct inotify_event *e;
        ssize_t l;
        int r;

        assert(manager);

        r = event_source_disable(manager->kill_workers_event);
        if (r < 0)
                log_warning_errno(r, "Failed to disable event source for cleaning up idle workers, ignoring: %m");

        l = read(fd, &buffer, sizeof(buffer));
        if (l < 0) {
                if (IN_SET(errno, EAGAIN, EINTR))
                        return 1;

                return log_error_errno(errno, "Failed to read inotify fd: %m");
        }

        FOREACH_INOTIFY_EVENT(e, buffer, l) {
                _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
                const char *devnode;

                if (udev_watch_lookup(e->wd, &dev) <= 0)
                        continue;

                if (sd_device_get_devname(dev, &devnode) < 0)
                        continue;

                log_device_debug(dev, "Inotify event: %x for %s", e->mask, devnode);
                if (e->mask & IN_CLOSE_WRITE)
                        synthesize_change(dev);
                else if (e->mask & IN_IGNORED)
                        udev_watch_end(dev);
        }

        return 1;
}

static int on_sigterm(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
        Manager *manager = userdata;

        assert(manager);

        manager_exit(manager);

        return 1;
}

static int on_sighup(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
        Manager *manager = userdata;

        assert(manager);

        manager_reload(manager);

        return 1;
}

static int on_sigchld(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
        Manager *manager = userdata;
        int r;

        assert(manager);

        for (;;) {
                pid_t pid;
                int status;
                struct worker *worker;

                pid = waitpid(-1, &status, WNOHANG);
                if (pid <= 0)
                        break;

                worker = hashmap_get(manager->workers, PID_TO_PTR(pid));
                if (!worker) {
                        log_warning("Worker ["PID_FMT"] is unknown, ignoring", pid);
                        continue;
                }

                if (WIFEXITED(status)) {
                        if (WEXITSTATUS(status) == 0)
                                log_debug("Worker ["PID_FMT"] exited", pid);
                        else
                                log_warning("Worker ["PID_FMT"] exited with return code %i", pid, WEXITSTATUS(status));
                } else if (WIFSIGNALED(status)) {
                        log_warning("Worker ["PID_FMT"] terminated by signal %i (%s)", pid, WTERMSIG(status), signal_to_string(WTERMSIG(status)));
                } else if (WIFSTOPPED(status)) {
                        log_info("Worker ["PID_FMT"] stopped", pid);
                        continue;
                } else if (WIFCONTINUED(status)) {
                        log_info("Worker ["PID_FMT"] continued", pid);
                        continue;
                } else
                        log_warning("Worker ["PID_FMT"] exit with status 0x%04x", pid, status);

                if ((!WIFEXITED(status) || WEXITSTATUS(status) != 0) && worker->event) {
                        log_device_error(worker->event->dev, "Worker ["PID_FMT"] failed", pid);

                        /* delete state from disk */
                        device_delete_db(worker->event->dev);
                        device_tag_index(worker->event->dev, NULL, false);

                        /* forward kernel event without amending it */
                        r = device_monitor_send_device(manager->monitor, NULL, worker->event->dev_kernel);
                        if (r < 0)
                                log_device_error_errno(worker->event->dev_kernel, r, "Failed to send back device to kernel: %m");
                }

                worker_free(worker);
        }

        /* we can start new workers, try to schedule events */
        event_queue_start(manager);

        /* Disable unnecessary cleanup event */
        if (hashmap_isempty(manager->workers)) {
                r = event_source_disable(manager->kill_workers_event);
                if (r < 0)
                        log_warning_errno(r, "Failed to disable event source for cleaning up idle workers, ignoring: %m");
        }

        return 1;
}

static int on_post(sd_event_source *s, void *userdata) {
        Manager *manager = userdata;

        assert(manager);

        if (!LIST_IS_EMPTY(manager->events))
                return 1;

        /* There are no pending events. Let's cleanup idle process. */

        if (!hashmap_isempty(manager->workers)) {
                /* There are idle workers */
                (void) event_reset_time(manager->event, &manager->kill_workers_event, CLOCK_MONOTONIC,
                                        now(CLOCK_MONOTONIC) + 3 * USEC_PER_SEC, USEC_PER_SEC,
                                        on_kill_workers_event, manager, 0, "kill-workers-event", false);
                return 1;
        }

        /* There are no idle workers. */

        if (manager->exit)
                return sd_event_exit(manager->event, 0);

        if (manager->cgroup)
                /* cleanup possible left-over processes in our cgroup */
                (void) cg_kill(SYSTEMD_CGROUP_CONTROLLER, manager->cgroup, SIGKILL, CGROUP_IGNORE_SELF, NULL, NULL, NULL);

        return 1;
}

static int listen_fds(int *ret_ctrl, int *ret_netlink) {
        int ctrl_fd = -1, netlink_fd = -1;
        int fd, n;

        assert(ret_ctrl);
        assert(ret_netlink);

        n = sd_listen_fds(true);
        if (n < 0)
                return n;

        for (fd = SD_LISTEN_FDS_START; fd < n + SD_LISTEN_FDS_START; fd++) {
                if (sd_is_socket(fd, AF_LOCAL, SOCK_SEQPACKET, -1) > 0) {
                        if (ctrl_fd >= 0)
                                return -EINVAL;
                        ctrl_fd = fd;
                        continue;
                }

                if (sd_is_socket(fd, AF_NETLINK, SOCK_RAW, -1) > 0) {
                        if (netlink_fd >= 0)
                                return -EINVAL;
                        netlink_fd = fd;
                        continue;
                }

                return -EINVAL;
        }

        *ret_ctrl = ctrl_fd;
        *ret_netlink = netlink_fd;

        return 0;
}

/*
 * read the kernel command line, in case we need to get into debug mode
 *   udev.log_priority=<level>                 syslog priority
 *   udev.children_max=<number of workers>     events are fully serialized if set to 1
 *   udev.exec_delay=<number of seconds>       delay execution of every executed program
 *   udev.event_timeout=<number of seconds>    seconds to wait before terminating an event
 */
static int parse_proc_cmdline_item(const char *key, const char *value, void *data) {
        int r = 0;

        assert(key);

        if (!value)
                return 0;

        if (proc_cmdline_key_streq(key, "udev.log_priority")) {

                if (proc_cmdline_value_missing(key, value))
                        return 0;

                r = log_level_from_string(value);
                if (r >= 0)
                        log_set_max_level(r);

        } else if (proc_cmdline_key_streq(key, "udev.event_timeout")) {

                if (proc_cmdline_value_missing(key, value))
                        return 0;

                r = parse_sec(value, &arg_event_timeout_usec);

        } else if (proc_cmdline_key_streq(key, "udev.children_max")) {

                if (proc_cmdline_value_missing(key, value))
                        return 0;

                r = safe_atou(value, &arg_children_max);

        } else if (proc_cmdline_key_streq(key, "udev.exec_delay")) {

                if (proc_cmdline_value_missing(key, value))
                        return 0;

                r = parse_sec(value, &arg_exec_delay_usec);

        } else if (startswith(key, "udev."))
                log_warning("Unknown udev kernel command line option \"%s\", ignoring", key);

        if (r < 0)
                log_warning_errno(r, "Failed to parse \"%s=%s\", ignoring: %m", key, value);

        return 0;
}

static int help(void) {
        _cleanup_free_ char *link = NULL;
        int r;

        r = terminal_urlify_man("systemd-udevd.service", "8", &link);
        if (r < 0)
                return log_oom();

        printf("%s [OPTIONS...]\n\n"
               "Manages devices.\n\n"
               "  -h --help                   Print this message\n"
               "  -V --version                Print version of the program\n"
               "  -d --daemon                 Detach and run in the background\n"
               "  -D --debug                  Enable debug output\n"
               "  -c --children-max=INT       Set maximum number of workers\n"
               "  -e --exec-delay=SECONDS     Seconds to wait before executing RUN=\n"
               "  -t --event-timeout=SECONDS  Seconds to wait before terminating an event\n"
               "  -N --resolve-names=early|late|never\n"
               "                              When to resolve users and groups\n"
               "\nSee the %s for details.\n"
               , program_invocation_short_name
               , link
        );

        return 0;
}

static int parse_argv(int argc, char *argv[]) {
        static const struct option options[] = {
                { "daemon",             no_argument,            NULL, 'd' },
                { "debug",              no_argument,            NULL, 'D' },
                { "children-max",       required_argument,      NULL, 'c' },
                { "exec-delay",         required_argument,      NULL, 'e' },
                { "event-timeout",      required_argument,      NULL, 't' },
                { "resolve-names",      required_argument,      NULL, 'N' },
                { "help",               no_argument,            NULL, 'h' },
                { "version",            no_argument,            NULL, 'V' },
                {}
        };

        int c, r;

        assert(argc >= 0);
        assert(argv);

        while ((c = getopt_long(argc, argv, "c:de:Dt:N:hV", options, NULL)) >= 0) {
                switch (c) {

                case 'd':
                        arg_daemonize = true;
                        break;
                case 'c':
                        r = safe_atou(optarg, &arg_children_max);
                        if (r < 0)
                                log_warning_errno(r, "Failed to parse --children-max= value '%s', ignoring: %m", optarg);
                        break;
                case 'e':
                        r = parse_sec(optarg, &arg_exec_delay_usec);
                        if (r < 0)
                                log_warning_errno(r, "Failed to parse --exec-delay= value '%s', ignoring: %m", optarg);
                        break;
                case 't':
                        r = parse_sec(optarg, &arg_event_timeout_usec);
                        if (r < 0)
                                log_warning_errno(r, "Failed to parse --event-timeout= value '%s', ignoring: %m", optarg);
                        break;
                case 'D':
                        arg_debug = true;
                        break;
                case 'N': {
                        ResolveNameTiming t;

                        t = resolve_name_timing_from_string(optarg);
                        if (t < 0)
                                log_warning("Invalid --resolve-names= value '%s', ignoring.", optarg);
                        else
                                arg_resolve_name_timing = t;
                        break;
                }
                case 'h':
                        return help();
                case 'V':
                        printf("%s\n", GIT_VERSION);
                        return 0;
                case '?':
                        return -EINVAL;
                default:
                        assert_not_reached("Unhandled option");

                }
        }

        return 1;
}

static int manager_new(Manager **ret, int fd_ctrl, int fd_uevent, const char *cgroup) {
        _cleanup_(manager_freep) Manager *manager = NULL;
        int r, fd_worker;

        assert(ret);

        manager = new(Manager, 1);
        if (!manager)
                return log_oom();

        *manager = (Manager) {
                .fd_inotify = -1,
                .worker_watch = { -1, -1 },
                .cgroup = cgroup,
        };

        udev_builtin_init();

        r = udev_rules_new(&manager->rules, arg_resolve_name_timing);
        if (!manager->rules)
                return log_error_errno(r, "Failed to read udev rules: %m");

        manager->ctrl = udev_ctrl_new_from_fd(fd_ctrl);
        if (!manager->ctrl)
                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize udev control socket");

        if (fd_ctrl < 0) {
                r = udev_ctrl_enable_receiving(manager->ctrl);
                if (r < 0)
                        return log_error_errno(r, "Failed to bind udev control socket: %m");
        }

        fd_ctrl = udev_ctrl_get_fd(manager->ctrl);
        if (fd_ctrl < 0)
                return log_error_errno(fd_ctrl, "Failed to get udev control socket fd: %m");

        r = device_monitor_new_full(&manager->monitor, MONITOR_GROUP_KERNEL, fd_uevent);
        if (r < 0)
                return log_error_errno(r, "Failed to initialize device monitor: %m");

        (void) sd_device_monitor_set_receive_buffer_size(manager->monitor, 128 * 1024 * 1024);

        /* unnamed socket from workers to the main daemon */
        r = socketpair(AF_LOCAL, SOCK_DGRAM|SOCK_CLOEXEC, 0, manager->worker_watch);
        if (r < 0)
                return log_error_errno(errno, "Failed to create socketpair for communicating with workers: %m");

        fd_worker = manager->worker_watch[READ_END];

        r = setsockopt_int(fd_worker, SOL_SOCKET, SO_PASSCRED, true);
        if (r < 0)
                return log_error_errno(r, "Failed to enable SO_PASSCRED: %m");

        r = udev_watch_init();
        if (r < 0)
                return log_error_errno(r, "Failed to create inotify descriptor: %m");
        manager->fd_inotify = r;

        udev_watch_restore();

        /* block and listen to all signals on signalfd */
        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGHUP, SIGCHLD, -1) >= 0);

        r = sd_event_default(&manager->event);
        if (r < 0)
                return log_error_errno(r, "Failed to allocate event loop: %m");

        r = sd_event_add_signal(manager->event, NULL, SIGINT, on_sigterm, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to create SIGINT event source: %m");

        r = sd_event_add_signal(manager->event, NULL, SIGTERM, on_sigterm, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to create SIGTERM event source: %m");

        r = sd_event_add_signal(manager->event, NULL, SIGHUP, on_sighup, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to create SIGHUP event source: %m");

        r = sd_event_add_signal(manager->event, NULL, SIGCHLD, on_sigchld, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to create SIGCHLD event source: %m");

        r = sd_event_set_watchdog(manager->event, true);
        if (r < 0)
                return log_error_errno(r, "Failed to create watchdog event source: %m");

        r = sd_event_add_io(manager->event, &manager->ctrl_event, fd_ctrl, EPOLLIN, on_ctrl_msg, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to create udev control event source: %m");

        /* This needs to be after the inotify and uevent handling, to make sure
         * that the ping is send back after fully processing the pending uevents
         * (including the synthetic ones we may create due to inotify events).
         */
        r = sd_event_source_set_priority(manager->ctrl_event, SD_EVENT_PRIORITY_IDLE);
        if (r < 0)
                return log_error_errno(r, "Failed to set IDLE event priority for udev control event source: %m");

        r = sd_event_add_io(manager->event, &manager->inotify_event, manager->fd_inotify, EPOLLIN, on_inotify, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to create inotify event source: %m");

        r = sd_device_monitor_attach_event(manager->monitor, manager->event);
        if (r < 0)
                return log_error_errno(r, "Failed to attach event to device monitor: %m");

        r = sd_device_monitor_start(manager->monitor, on_uevent, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to start device monitor: %m");

        (void) sd_event_source_set_description(sd_device_monitor_get_event_source(manager->monitor), "device-monitor");

        r = sd_event_add_io(manager->event, NULL, fd_worker, EPOLLIN, on_worker, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to create worker event source: %m");

        r = sd_event_add_post(manager->event, NULL, on_post, manager);
        if (r < 0)
                return log_error_errno(r, "Failed to create post event source: %m");

        *ret = TAKE_PTR(manager);

        return 0;
}

static int main_loop(int fd_ctrl, int fd_uevent, const char *cgroup) {
        _cleanup_(manager_freep) Manager *manager = NULL;
        int r;

        r = manager_new(&manager, fd_ctrl, fd_uevent, cgroup);
        if (r < 0) {
                r = log_error_errno(r, "Failed to allocate manager object: %m");
                goto exit;
        }

        r = udev_rules_apply_static_dev_perms(manager->rules);
        if (r < 0)
                log_error_errno(r, "Failed to apply permissions on static device nodes: %m");

        (void) sd_notifyf(false,
                          "READY=1\n"
                          "STATUS=Processing with %u children at max", arg_children_max);

        r = sd_event_loop(manager->event);
        if (r < 0) {
                log_error_errno(r, "Event loop failed: %m");
                goto exit;
        }

        sd_event_get_exit_code(manager->event, &r);

exit:
        sd_notify(false,
                  "STOPPING=1\n"
                  "STATUS=Shutting down...");
        if (manager)
                udev_ctrl_cleanup(manager->ctrl);
        return r;
}

static int run(int argc, char *argv[]) {
        _cleanup_free_ char *cgroup = NULL;
        int fd_ctrl = -1, fd_uevent = -1;
        int r;

        log_set_target(LOG_TARGET_AUTO);
        udev_parse_config_full(&arg_children_max, &arg_exec_delay_usec, &arg_event_timeout_usec, &arg_resolve_name_timing);
        log_parse_environment();
        log_open();

        r = parse_argv(argc, argv);
        if (r <= 0)
                return r;

        r = proc_cmdline_parse(parse_proc_cmdline_item, NULL, PROC_CMDLINE_STRIP_RD_PREFIX);
        if (r < 0)
                log_warning_errno(r, "Failed to parse kernel command line, ignoring: %m");

        if (arg_debug) {
                log_set_target(LOG_TARGET_CONSOLE);
                log_set_max_level(LOG_DEBUG);
        }

        log_set_max_level_realm(LOG_REALM_SYSTEMD, log_get_max_level());

        r = must_be_root();
        if (r < 0)
                return r;

        if (arg_children_max == 0) {
                cpu_set_t cpu_set;
                unsigned long mem_limit;

                arg_children_max = 8;

                if (sched_getaffinity(0, sizeof(cpu_set), &cpu_set) == 0)
                        arg_children_max += CPU_COUNT(&cpu_set) * 8;

                mem_limit = physical_memory() / (128LU*1024*1024);
                arg_children_max = MAX(10U, MIN(arg_children_max, mem_limit));

                log_debug("Set children_max to %u", arg_children_max);
        }

        /* set umask before creating any file/directory */
        r = chdir("/");
        if (r < 0)
                return log_error_errno(errno, "Failed to change dir to '/': %m");

        umask(022);

        r = mac_selinux_init();
        if (r < 0)
                return log_error_errno(r, "Could not initialize labelling: %m");

        r = mkdir_errno_wrapper("/run/udev", 0755);
        if (r < 0 && r != -EEXIST)
                return log_error_errno(r, "Failed to create /run/udev: %m");

        dev_setup(NULL, UID_INVALID, GID_INVALID);

        if (getppid() == 1) {
                /* get our own cgroup, we regularly kill everything udev has left behind
                   we only do this on systemd systems, and only if we are directly spawned
                   by PID1. otherwise we are not guaranteed to have a dedicated cgroup */
                r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, 0, &cgroup);
                if (r < 0) {
                        if (IN_SET(r, -ENOENT, -ENOMEDIUM))
                                log_debug_errno(r, "Dedicated cgroup not found: %m");
                        else
                                log_warning_errno(r, "Failed to get cgroup: %m");
                }
        }

        r = listen_fds(&fd_ctrl, &fd_uevent);
        if (r < 0)
                return log_error_errno(r, "Failed to listen on fds: %m");

        if (arg_daemonize) {
                pid_t pid;

                log_info("starting version " GIT_VERSION);

                /* connect /dev/null to stdin, stdout, stderr */
                if (log_get_max_level() < LOG_DEBUG) {
                        r = make_null_stdio();
                        if (r < 0)
                                log_warning_errno(r, "Failed to redirect standard streams to /dev/null: %m");
                }

                pid = fork();
                if (pid < 0)
                        return log_error_errno(errno, "Failed to fork daemon: %m");
                if (pid > 0)
                        /* parent */
                        return 0;

                /* child */
                (void) setsid();

                r = set_oom_score_adjust(-1000);
                if (r < 0)
                        log_debug_errno(r, "Failed to adjust OOM score, ignoring: %m");
        }

        return main_loop(fd_ctrl, fd_uevent, cgroup);
}

DEFINE_MAIN_FUNCTION(run);