/*

 * uevent.c - trigger upon netlink uevents from the kernel

 *

 *	Only kernels from version 2.6.10* on provide the uevent netlink socket.

 *	Until the libc-kernel-headers are updated, you need to compile with:

 *

 *	  gcc -I /lib/modules/`uname -r`/build/include -o uevent_listen uevent_listen.c

 *

 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>

 *

 *	This program is free software; you can redistribute it and/or modify it

 *	under the terms of the GNU General Public License as published by the

 *	Free Software Foundation version 2 of the License.

 *

 *	This program 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

 *	General Public License for more details.

 *

 *	You should have received a copy of the GNU General Public License along

 *	with this program.  If not, see <http://www.gnu.org/licenses/>.

 *

 */

#include <unistd.h>

#include <stdio.h>

#include <stdbool.h>

#include <errno.h>

#include <stdlib.h>

#include <stddef.h>

#include <string.h>

#include <fcntl.h>

#include <time.h>

#include <sys/socket.h>

#include <sys/user.h>

#include <sys/un.h>

#include <poll.h>

#include <linux/types.h>

#include <linux/netlink.h>

#include <pthread.h>

#include <sys/mman.h>

#include <sys/time.h>

#include <libudev.h>

#include <errno.h>

#include "memory.h"

#include "debug.h"

#include "list.h"

#include "uevent.h"

#include "vector.h"

#include "structs.h"

#include "util.h"

#include "config.h"

#include "blacklist.h"

#include "devmapper.h"

#define MAX_ACCUMULATION_COUNT 2048

#define MAX_ACCUMULATION_TIME 30*1000

#define MIN_BURST_SPEED 10

typedef int (uev_trigger)(struct uevent *, void * trigger_data);

LIST_HEAD(uevq);

pthread_mutex_t uevq_lock = PTHREAD_MUTEX_INITIALIZER;

pthread_mutex_t *uevq_lockp = &uevq_lock;

pthread_cond_t uev_cond = PTHREAD_COND_INITIALIZER;

pthread_cond_t *uev_condp = &uev_cond;

uev_trigger *my_uev_trigger;

void * my_trigger_data;

int servicing_uev;

int is_uevent_busy(void)

{

	int empty;

	pthread_mutex_lock(uevq_lockp);

	empty = list_empty(&uevq);

	pthread_mutex_unlock(uevq_lockp);

	return (!empty || servicing_uev);

}

struct uevent * alloc_uevent (void)

{

	struct uevent *uev = MALLOC(sizeof(struct uevent));

	if (uev) {

		INIT_LIST_HEAD(&uev->node);

		INIT_LIST_HEAD(&uev->merge_node);

	}

	return uev;

}

void

uevq_cleanup(struct list_head *tmpq)

{

	struct uevent *uev, *tmp;

	list_for_each_entry_safe(uev, tmp, tmpq, node) {

		list_del_init(&uev->node);

		if (uev->udev)

			udev_device_unref(uev->udev);

		FREE(uev);

	}

}

static const char* uevent_get_env_var(const struct uevent *uev,

				      const char *attr)

{

	int i;

	size_t len;

	const char *p = NULL;

	if (attr == NULL)

		goto invalid;

	len = strlen(attr);

	if (len == 0)

		goto invalid;

	for (i = 0; uev->envp[i] != NULL; i++) {

		const char *var = uev->envp[i];

		if (strlen(var) > len &&

		    !memcmp(var, attr, len) && var[len] == '=') {

			p = var + len + 1;

			break;

		}

	}

	condlog(4, "%s: %s -> '%s'", __func__, attr, p);

	return p;

invalid:

	condlog(2, "%s: empty variable name", __func__);

	return NULL;

}

static int uevent_get_env_positive_int(const struct uevent *uev,

				       const char *attr)

{

	const char *p = uevent_get_env_var(uev, attr);

	char *q;

	int ret;

	if (p == NULL || *p == '\0')

		return -1;

	ret = strtoul(p, &q, 10);

	if (*q != '\0' || ret < 0) {

		condlog(2, "%s: invalid %s: '%s'", __func__, attr, p);

		return -1;

	}

	return ret;

}

void

uevent_get_wwid(struct uevent *uev)

{

	char *uid_attribute;

	const char *val;

	struct config * conf;

	conf = get_multipath_config();

	pthread_cleanup_push(put_multipath_config, conf);

	uid_attribute = get_uid_attribute_by_attrs(conf, uev->kernel);

	pthread_cleanup_pop(1);

	val = uevent_get_env_var(uev, uid_attribute);

	if (val)

		uev->wwid = val;

}

bool

uevent_need_merge(void)

{

	struct config * conf;

	bool need_merge = false;

	conf = get_multipath_config();

	if (VECTOR_SIZE(&conf->uid_attrs) > 0)

		need_merge = true;

	put_multipath_config(conf);

	return need_merge;

}

bool

uevent_can_discard(struct uevent *uev)

{

	int invalid = 0;

	struct config * conf;

	/*

	 * do not filter dm devices by devnode

	 */

	if (!strncmp(uev->kernel, "dm-", 3))

		return false;

	/*

	 * filter paths devices by devnode

	 */

	conf = get_multipath_config();

	pthread_cleanup_push(put_multipath_config, conf);

	if (filter_devnode(conf->blist_devnode, conf->elist_devnode,

			   uev->kernel) > 0)

		invalid = 1;

	pthread_cleanup_pop(1);

	if (invalid)

		return true;

	return false;

}

bool

uevent_can_filter(struct uevent *earlier, struct uevent *later)

{

	/*

	 * filter earlier uvents if path has removed later. Eg:

	 * "add path1 |chang path1 |add path2 |remove path1"

	 * can filter as:

	 * "add path2 |remove path1"

	 * uevents "add path1" and "chang path1" are filtered out

	 */

	if (!strcmp(earlier->kernel, later->kernel) &&

		!strcmp(later->action, "remove") &&

		strncmp(later->kernel, "dm-", 3)) {

		return true;

	}

	/*

	 * filter change uvents if add uevents exist. Eg:

	 * "change path1| add path1 |add path2"

	 * can filter as:

	 * "add path1 |add path2"

	 * uevent "chang path1" is filtered out

	 */

	if (!strcmp(earlier->kernel, later->kernel) &&

		!strcmp(earlier->action, "change") &&

		!strcmp(later->action, "add") &&

		strncmp(later->kernel, "dm-", 3)) {

		return true;

	}

	return false;

}

bool

merge_need_stop(struct uevent *earlier, struct uevent *later)

{

	/*

	 * dm uevent do not try to merge with left uevents

	 */

	if (!strncmp(later->kernel, "dm-", 3))

		return true;

	/*

	 * we can not make a jugement without wwid,

	 * so it is sensible to stop merging

	 */

	if (!earlier->wwid || !later->wwid)

		return true;

	/*

	 * uevents merging stopped

	 * when we meet an opposite action uevent from the same LUN to AVOID

	 * "add path1 |remove path1 |add path2 |remove path2 |add path3"

	 * to merge as "remove path1, path2" and "add path1, path2, path3"

	 * OR

	 * "remove path1 |add path1 |remove path2 |add path2 |remove path3"

	 * to merge as "add path1, path2" and "remove path1, path2, path3"

	 * SO

	 * when we meet a non-change uevent from the same LUN

	 * with the same wwid and different action

	 * it would be better to stop merging.

	 */

	if (!strcmp(earlier->wwid, later->wwid) &&

	    strcmp(earlier->action, later->action) &&

	    strcmp(earlier->action, "change") &&

	    strcmp(later->action, "change"))

		return true;

	return false;

}

bool

uevent_can_merge(struct uevent *earlier, struct uevent *later)

{

	/* merge paths uevents

	 * whose wwids exsit and are same

	 * and actions are same,

	 * and actions are addition or deletion

	 */

	if (earlier->wwid && later->wwid &&

	    !strcmp(earlier->wwid, later->wwid) &&

	    !strcmp(earlier->action, later->action) &&

	    strncmp(earlier->action, "change", 6) &&

	    strncmp(earlier->kernel, "dm-", 3)) {

		return true;

	}

	return false;

}

void

uevent_prepare(struct list_head *tmpq)

{

	struct uevent *uev, *tmp;

	list_for_each_entry_reverse_safe(uev, tmp, tmpq, node) {

		if (uevent_can_discard(uev)) {

			list_del_init(&uev->node);

			if (uev->udev)

				udev_device_unref(uev->udev);

			FREE(uev);

			continue;

		}

		if (strncmp(uev->kernel, "dm-", 3) &&

		    uevent_need_merge())

			uevent_get_wwid(uev);

	}

}

void

uevent_filter(struct uevent *later, struct list_head *tmpq)

{

	struct uevent *earlier, *tmp;

	list_for_some_entry_reverse_safe(earlier, tmp, &later->node, tmpq, node) {

		/*

		 * filter unnessary earlier uevents

		 * by the later uevent

		 */

		if (uevent_can_filter(earlier, later)) {

			condlog(3, "uevent: %s-%s has filtered by uevent: %s-%s",

				earlier->kernel, earlier->action,

				later->kernel, later->action);

			list_del_init(&earlier->node);

			if (earlier->udev)

				udev_device_unref(earlier->udev);

			FREE(earlier);

		}

	}

}

void

uevent_merge(struct uevent *later, struct list_head *tmpq)

{

	struct uevent *earlier, *tmp;

	list_for_some_entry_reverse_safe(earlier, tmp, &later->node, tmpq, node) {

		if (merge_need_stop(earlier, later))

			break;

		/*

		 * merge earlier uevents to the later uevent

		 */

		if (uevent_can_merge(earlier, later)) {

			condlog(3, "merged uevent: %s-%s-%s with uevent: %s-%s-%s",

				earlier->action, earlier->kernel, earlier->wwid,

				later->action, later->kernel, later->wwid);

			list_move(&earlier->node, &later->merge_node);

		}

	}

}

void

merge_uevq(struct list_head *tmpq)

{

	struct uevent *later;

	uevent_prepare(tmpq);

	list_for_each_entry_reverse(later, tmpq, node) {

		uevent_filter(later, tmpq);

		if(uevent_need_merge())

			uevent_merge(later, tmpq);

	}

}

void

service_uevq(struct list_head *tmpq)

{

	struct uevent *uev, *tmp;

	list_for_each_entry_safe(uev, tmp, tmpq, node) {

		list_del_init(&uev->node);

		if (my_uev_trigger && my_uev_trigger(uev, my_trigger_data))

			condlog(0, "uevent trigger error");

		uevq_cleanup(&uev->merge_node);

		if (uev->udev)

			udev_device_unref(uev->udev);

		FREE(uev);

	}

}

static void uevent_cleanup(void *arg)

{

	struct udev *udev = arg;

	condlog(3, "Releasing uevent_listen() resources");

	udev_unref(udev);

}

static void monitor_cleanup(void *arg)

{

	struct udev_monitor *monitor = arg;

	condlog(3, "Releasing uevent_monitor() resources");

	udev_monitor_unref(monitor);

}

/*

 * Service the uevent queue.

 */

int uevent_dispatch(int (*uev_trigger)(struct uevent *, void * trigger_data),

		    void * trigger_data)

{

	my_uev_trigger = uev_trigger;

	my_trigger_data = trigger_data;

	mlockall(MCL_CURRENT | MCL_FUTURE);

	while (1) {

		LIST_HEAD(uevq_tmp);

		pthread_mutex_lock(uevq_lockp);

		servicing_uev = 0;

		/*

		 * Condition signals are unreliable,

		 * so make sure we only wait if we have to.

		 */

		if (list_empty(&uevq)) {

			pthread_cond_wait(uev_condp, uevq_lockp);

		}

		servicing_uev = 1;

		list_splice_init(&uevq, &uevq_tmp);

		pthread_mutex_unlock(uevq_lockp);

		if (!my_uev_trigger)

			break;

		merge_uevq(&uevq_tmp);

		service_uevq(&uevq_tmp);

	}

	condlog(3, "Terminating uev service queue");

	uevq_cleanup(&uevq);

	return 0;

}

struct uevent *uevent_from_buffer(char *buf, ssize_t buflen)

{

	struct uevent *uev;

	char *buffer;

	size_t bufpos;

	int i;

	char *pos;

	uev = alloc_uevent();

	if (!uev) {

		condlog(1, "lost uevent, oom");

		return NULL;

	}

	if ((size_t)buflen > sizeof(buf)-1)

		buflen = sizeof(buf)-1;

	/*

	 * Copy the shared receive buffer contents to buffer private

	 * to this uevent so we can immediately reuse the shared buffer.

	 */

	memcpy(uev->buffer, buf, HOTPLUG_BUFFER_SIZE + OBJECT_SIZE);

	buffer = uev->buffer;

	buffer[buflen] = '\0';

	/* save start of payload */

	bufpos = strlen(buffer) + 1;

	/* action string */

	uev->action = buffer;

	pos = strchr(buffer, '@');

	if (!pos) {

		condlog(3, "bad action string '%s'", buffer);

		FREE(uev);

		return NULL;

	}

	pos[0] = '\0';

	/* sysfs path */

	uev->devpath = &pos[1];

	/* hotplug events have the environment attached - reconstruct envp[] */

	for (i = 0; (bufpos < (size_t)buflen) && (i < HOTPLUG_NUM_ENVP-1); i++) {

		int keylen;

		char *key;

		key = &buffer[bufpos];

		keylen = strlen(key);

		uev->envp[i] = key;

		/* Filter out sequence number */

		if (strncmp(key, "SEQNUM=", 7) == 0) {

			char *eptr;

			uev->seqnum = strtoul(key + 7, &eptr, 10);

			if (eptr == key + 7)

				uev->seqnum = -1;

		}

		bufpos += keylen + 1;

	}

	uev->envp[i] = NULL;

	condlog(3, "uevent %ld '%s' from '%s'", uev->seqnum,

		uev->action, uev->devpath);

	uev->kernel = strrchr(uev->devpath, '/');

	if (uev->kernel)

		uev->kernel++;

	/* print payload environment */

	for (i = 0; uev->envp[i] != NULL; i++)

		condlog(5, "%s", uev->envp[i]);

	return uev;

}

int failback_listen(void)

{

	int sock;

	struct sockaddr_nl snl;

	struct sockaddr_un sun;

	socklen_t addrlen;

	int retval;

	int rcvbufsz = 128*1024;

	int rcvsz = 0;

	int rcvszsz = sizeof(rcvsz);

	unsigned int *prcvszsz = (unsigned int *)&rcvszsz;

	const int feature_on = 1;

	/*

	 * First check whether we have a udev socket

	 */

	memset(&sun, 0x00, sizeof(struct sockaddr_un));

	sun.sun_family = AF_LOCAL;

	strcpy(&sun.sun_path[1], "/org/kernel/dm/multipath_event");

	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(sun.sun_path+1) + 1;

	sock = socket(AF_LOCAL, SOCK_DGRAM, 0);

	if (sock >= 0) {

		condlog(3, "reading events from udev socket.");

		/* the bind takes care of ensuring only one copy running */

		retval = bind(sock, (struct sockaddr *) &sun, addrlen);

		if (retval < 0) {

			condlog(0, "bind failed, exit");

			goto exit;

		}

		/* enable receiving of the sender credentials */

		retval = setsockopt(sock, SOL_SOCKET, SO_PASSCRED,

				    &feature_on, sizeof(feature_on));

		if (retval < 0) {

			condlog(0, "failed to enable credential passing, exit");

			goto exit;

		}

	} else {

		/* Fallback to read kernel netlink events */

		memset(&snl, 0x00, sizeof(struct sockaddr_nl));

		snl.nl_family = AF_NETLINK;

		snl.nl_pid = getpid();

		snl.nl_groups = 0x01;

		sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);

		if (sock == -1) {

			condlog(0, "error getting socket, exit");

			return 1;

		}

		condlog(3, "reading events from kernel.");

		/*

		 * try to avoid dropping uevents, even so, this is not a guarantee,

		 * but it does help to change the netlink uevent socket's

		 * receive buffer threshold from the default value of 106,496 to

		 * the maximum value of 262,142.

		 */

		retval = setsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvbufsz,

				    sizeof(rcvbufsz));

		if (retval < 0) {

			condlog(0, "error setting receive buffer size for socket, exit");

			exit(1);

		}

		retval = getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvsz, prcvszsz);

		if (retval < 0) {

			condlog(0, "error setting receive buffer size for socket, exit");

			exit(1);

		}

		condlog(3, "receive buffer size for socket is %u.", rcvsz);

		/* enable receiving of the sender credentials */

		if (setsockopt(sock, SOL_SOCKET, SO_PASSCRED,

			       &feature_on, sizeof(feature_on)) < 0) {

			condlog(0, "error on enabling credential passing for socket");

			exit(1);

		}

		retval = bind(sock, (struct sockaddr *) &snl,

			      sizeof(struct sockaddr_nl));

		if (retval < 0) {

			condlog(0, "bind failed, exit");

			goto exit;

		}

	}

	while (1) {

		size_t bufpos;

		ssize_t buflen;

		struct uevent *uev;

		struct msghdr smsg;

		struct iovec iov;

		char cred_msg[CMSG_SPACE(sizeof(struct ucred))];

		struct cmsghdr *cmsg;

		struct ucred *cred;

		static char buf[HOTPLUG_BUFFER_SIZE + OBJECT_SIZE];

		memset(buf, 0x00, sizeof(buf));

		iov.iov_base = &buf;

		iov.iov_len = sizeof(buf);

		memset (&smsg, 0x00, sizeof(struct msghdr));

		smsg.msg_iov = &iov;

		smsg.msg_iovlen = 1;

		smsg.msg_control = cred_msg;

		smsg.msg_controllen = sizeof(cred_msg);

		buflen = recvmsg(sock, &smsg, 0);

		if (buflen < 0) {

			if (errno != EINTR)

				condlog(0, "error receiving message, errno %d", errno);

			continue;

		}

		cmsg = CMSG_FIRSTHDR(&smsg);

		if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {

			condlog(3, "no sender credentials received, message ignored");

			continue;

		}

		cred = (struct ucred *)CMSG_DATA(cmsg);

		if (cred->uid != 0) {

			condlog(3, "sender uid=%d, message ignored", cred->uid);

			continue;

		}

		/* skip header */

		bufpos = strlen(buf) + 1;

		if (bufpos < sizeof("a@/d") || bufpos >= sizeof(buf)) {

			condlog(3, "invalid message length");

			continue;

		}

		/* check message header */

		if (strstr(buf, "@/") == NULL) {

			condlog(3, "unrecognized message header");

			continue;

		}

		if ((size_t)buflen > sizeof(buf)-1) {

			condlog(2, "buffer overflow for received uevent");

			buflen = sizeof(buf)-1;

		}

		uev = uevent_from_buffer(buf, buflen);

		if (!uev)

			continue;

		/*

		 * Queue uevent and poke service pthread.

		 */

		pthread_mutex_lock(uevq_lockp);

		list_add_tail(&uev->node, &uevq);

		pthread_cond_signal(uev_condp);

		pthread_mutex_unlock(uevq_lockp);

	}

exit:

	close(sock);

	return 1;

}

struct uevent *uevent_from_udev_device(struct udev_device *dev)

{

	struct uevent *uev;

	int i = 0;

	char *pos, *end;

	struct udev_list_entry *list_entry;

	uev = alloc_uevent();

	if (!uev) {

		udev_device_unref(dev);

		condlog(1, "lost uevent, oom");

		return NULL;

	}

	pos = uev->buffer;

	end = pos + HOTPLUG_BUFFER_SIZE + OBJECT_SIZE - 1;

	udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(dev)) {

		const char *name, *value;

		int bytes;

		name = udev_list_entry_get_name(list_entry);

		if (!name)

			name = "(null)";

		value = udev_list_entry_get_value(list_entry);

		if (!value)

			value = "(null)";

		bytes = snprintf(pos, end - pos, "%s=%s", name, value);

		if (pos + bytes >= end) {

			condlog(2, "buffer overflow for uevent");

			break;

		}

		uev->envp[i] = pos;

		pos += bytes;

		*pos = '\0';

		pos++;

		if (strcmp(name, "DEVPATH") == 0)

			uev->devpath = uev->envp[i] + 8;

		if (strcmp(name, "ACTION") == 0)

			uev->action = uev->envp[i] + 7;

		i++;

		if (i == HOTPLUG_NUM_ENVP - 1)

			break;

	}

	if (!uev->devpath || ! uev->action) {

		udev_device_unref(dev);

		condlog(1, "uevent missing necessary fields");

		FREE(uev);

		return NULL;

	}

	uev->udev = dev;

	uev->envp[i] = NULL;

	condlog(3, "uevent '%s' from '%s'", uev->action, uev->devpath);

	uev->kernel = strrchr(uev->devpath, '/');

	if (uev->kernel)

		uev->kernel++;

	/* print payload environment */

	for (i = 0; uev->envp[i] != NULL; i++)

		condlog(5, "%s", uev->envp[i]);

	return uev;

}

bool uevent_burst(struct timeval *start_time, int events)

{

	struct timeval diff_time, end_time;

	unsigned long speed;

	unsigned long eclipse_ms;

	if(events > MAX_ACCUMULATION_COUNT) {

		condlog(2, "burst got %u uevents, too much uevents, stopped", events);

		return false;

	}

	gettimeofday(&end_time, NULL);

	timersub(&end_time, start_time, &diff_time);

	eclipse_ms = diff_time.tv_sec * 1000 + diff_time.tv_usec / 1000;

	if (eclipse_ms == 0)

		return true;

	if (eclipse_ms > MAX_ACCUMULATION_TIME) {

		condlog(2, "burst continued %lu ms, too long time, stopped", eclipse_ms);

		return false;

	}

	speed = (events * 1000) / eclipse_ms;

	if (speed > MIN_BURST_SPEED)

		return true;

	return false;

}

int uevent_listen(struct udev *udev)

{

	int err = 2;

	struct udev_monitor *monitor = NULL;

	int fd, socket_flags, events;

	struct timeval start_time;

	int need_failback = 1;

	int timeout = 30;

	LIST_HEAD(uevlisten_tmp);

	/*

	 * Queue uevents for service by dedicated thread so that the uevent

	 * listening thread does not block on multipathd locks (vecs->lock)

	 * thereby not getting to empty the socket's receive buffer queue

	 * often enough.

	 */

	if (!udev) {

		condlog(1, "no udev context");

		return 1;

	}

	udev_ref(udev);

	pthread_cleanup_push(uevent_cleanup, udev);

	monitor = udev_monitor_new_from_netlink(udev, "udev");

	if (!monitor) {

		condlog(2, "failed to create udev monitor");

		goto failback;

	}

	pthread_cleanup_push(monitor_cleanup, monitor);

#ifdef LIBUDEV_API_RECVBUF

	if (udev_monitor_set_receive_buffer_size(monitor, 128 * 1024 * 1024))

		condlog(2, "failed to increase buffer size");

#endif

	fd = udev_monitor_get_fd(monitor);

	if (fd < 0) {

		condlog(2, "failed to get monitor fd");

		goto out;

	}

	socket_flags = fcntl(fd, F_GETFL);

	if (socket_flags < 0) {

		condlog(2, "failed to get monitor socket flags : %s",

			strerror(errno));

		goto out;

	}

	if (fcntl(fd, F_SETFL, socket_flags & ~O_NONBLOCK) < 0) {

		condlog(2, "failed to set monitor socket flags : %s",

			strerror(errno));

		goto out;

	}

	err = udev_monitor_filter_add_match_subsystem_devtype(monitor, "block",

							      "disk");

	if (err)

		condlog(2, "failed to create filter : %s", strerror(-err));

	err = udev_monitor_enable_receiving(monitor);

	if (err) {

		condlog(2, "failed to enable receiving : %s", strerror(-err));

		goto out;

	}

	events = 0;

	gettimeofday(&start_time, NULL);

	while (1) {

		struct uevent *uev;

		struct udev_device *dev;

		struct pollfd ev_poll;

		int poll_timeout;

		int fdcount;

		memset(&ev_poll, 0, sizeof(struct pollfd));

		ev_poll.fd = fd;

		ev_poll.events = POLLIN;

		poll_timeout = timeout * 1000;

		errno = 0;

		fdcount = poll(&ev_poll, 1, poll_timeout);

		if (fdcount > 0 && ev_poll.revents & POLLIN) {

			timeout = uevent_burst(&start_time, events + 1) ? 1 : 0;

			dev = udev_monitor_receive_device(monitor);

			if (!dev) {

				condlog(0, "failed getting udev device");

				continue;

			}

			uev = uevent_from_udev_device(dev);

			if (!uev)

				continue;

			list_add_tail(&uev->node, &uevlisten_tmp);

			events++;

			continue;

		}

		if (fdcount < 0) {

			if (errno == EINTR)

				continue;

			condlog(0, "error receiving "

				"uevent message: %m");

			err = -errno;

			break;

		}

		if (!list_empty(&uevlisten_tmp)) {