2 This file is part of systemd.
4 Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
6 systemd is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
11 systemd is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with systemd; If not, see <http://www.gnu.org/licenses/>.
29 #include <sys/socket.h>
31 #include <arpa/inet.h>
32 #include <linux/netlink.h>
33 #include <linux/filter.h>
36 #include "libudev-private.h"
37 #include "socket-util.h"
41 * SECTION:libudev-monitor
42 * @short_description: device event source
44 * Connects to a device event source.
50 * Opaque object handling an event source.
56 union sockaddr_union snl;
57 union sockaddr_union snl_trusted_sender;
58 union sockaddr_union snl_destination;
60 struct udev_list filter_subsystem_list;
61 struct udev_list filter_tag_list;
65 enum udev_monitor_netlink_group {
71 #define UDEV_MONITOR_MAGIC 0xfeedcafe
72 struct udev_monitor_netlink_header {
73 /* "libudev" prefix to distinguish libudev and kernel messages */
76 * magic to protect against daemon <-> library message format mismatch
77 * used in the kernel from socket filter rules; needs to be stored in network order
80 /* total length of header structure known to the sender */
81 unsigned int header_size;
82 /* properties string buffer */
83 unsigned int properties_off;
84 unsigned int properties_len;
86 * hashes of primary device properties strings, to let libudev subscribers
87 * use in-kernel socket filters; values need to be stored in network order
89 unsigned int filter_subsystem_hash;
90 unsigned int filter_devtype_hash;
91 unsigned int filter_tag_bloom_hi;
92 unsigned int filter_tag_bloom_lo;
95 static struct udev_monitor *udev_monitor_new(struct udev *udev)
97 struct udev_monitor *udev_monitor;
99 udev_monitor = calloc(1, sizeof(struct udev_monitor));
100 if (udev_monitor == NULL)
102 udev_monitor->refcount = 1;
103 udev_monitor->udev = udev;
104 udev_list_init(udev, &udev_monitor->filter_subsystem_list, false);
105 udev_list_init(udev, &udev_monitor->filter_tag_list, true);
109 /* we consider udev running when /dev is on devtmpfs */
110 static bool udev_has_devtmpfs(struct udev *udev) {
111 struct file_handle *h;
113 _cleanup_fclose_ FILE *f = NULL;
114 char line[LINE_MAX], *e;
117 h = alloca(MAX_HANDLE_SZ);
118 h->handle_bytes = MAX_HANDLE_SZ;
119 r = name_to_handle_at(AT_FDCWD, "/dev", h, &mount_id, 0);
124 f = fopen("/proc/self/mountinfo", "re");
128 FOREACH_LINE(line, f, return false) {
129 _cleanup_free_ char *opts = NULL;
132 if (sscanf(line, "%i", &mid) != 1)
138 e = strstr(line, " - ");
142 /* accept any name that starts with the currently expected type */
143 if (startswith(e + 3, "devtmpfs"))
150 /* we consider udev running when we have running udev service */
151 static bool udev_has_service(struct udev *udev) {
152 struct udev_queue *queue;
155 queue = udev_queue_new(udev);
159 active = udev_queue_get_udev_is_active(queue);
160 udev_queue_unref(queue);
165 struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
167 struct udev_monitor *udev_monitor;
174 group = UDEV_MONITOR_NONE;
175 else if (streq(name, "udev")) {
177 * We do not support subscribing to uevents if no instance of
178 * udev is running. Uevents would otherwise broadcast the
179 * processing data of the host into containers, which is not
182 * Containers will currently not get any udev uevents, until
183 * a supporting infrastructure is available.
185 * We do not set a netlink multicast group here, so the socket
186 * will not receive any messages.
188 if (!udev_has_service(udev) && !udev_has_devtmpfs(udev)) {
189 udev_dbg(udev, "the udev service seems not to be active, disable the monitor\n");
190 group = UDEV_MONITOR_NONE;
192 group = UDEV_MONITOR_UDEV;
193 } else if (streq(name, "kernel"))
194 group = UDEV_MONITOR_KERNEL;
198 udev_monitor = udev_monitor_new(udev);
199 if (udev_monitor == NULL)
203 udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
204 if (udev_monitor->sock == -1) {
205 udev_err(udev, "error getting socket: %m\n");
210 udev_monitor->bound = true;
211 udev_monitor->sock = fd;
214 udev_monitor->snl.nl.nl_family = AF_NETLINK;
215 udev_monitor->snl.nl.nl_groups = group;
217 /* default destination for sending */
218 udev_monitor->snl_destination.nl.nl_family = AF_NETLINK;
219 udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV;
225 * udev_monitor_new_from_netlink:
226 * @udev: udev library context
227 * @name: name of event source
229 * Create new udev monitor and connect to a specified event
230 * source. Valid sources identifiers are "udev" and "kernel".
232 * Applications should usually not connect directly to the
233 * "kernel" events, because the devices might not be useable
234 * at that time, before udev has configured them, and created
235 * device nodes. Accessing devices at the same time as udev,
236 * might result in unpredictable behavior. The "udev" events
237 * are sent out after udev has finished its event processing,
238 * all rules have been processed, and needed device nodes are
241 * The initial refcount is 1, and needs to be decremented to
242 * release the resources of the udev monitor.
244 * Returns: a new udev monitor, or #NULL, in case of an error
246 _public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
248 return udev_monitor_new_from_netlink_fd(udev, name, -1);
251 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
252 unsigned short code, unsigned int data)
254 struct sock_filter *ins = &inss[*i];
261 static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
262 unsigned short code, unsigned int data,
263 unsigned short jt, unsigned short jf)
265 struct sock_filter *ins = &inss[*i];
275 * udev_monitor_filter_update:
276 * @udev_monitor: monitor
278 * Update the installed socket filter. This is only needed,
279 * if the filter was removed or changed.
281 * Returns: 0 on success, otherwise a negative error value.
283 _public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
285 struct sock_filter ins[512];
286 struct sock_fprog filter;
288 struct udev_list_entry *list_entry;
291 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL &&
292 udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
295 memset(ins, 0x00, sizeof(ins));
298 /* load magic in A */
299 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
300 /* jump if magic matches */
301 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
302 /* wrong magic, pass packet */
303 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
305 if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) {
308 /* count tag matches, to calculate end of tag match block */
310 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list))
313 /* add all tags matches */
314 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
315 uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry));
316 uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
317 uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
319 /* load device bloom bits in A */
320 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi));
321 /* clear bits (tag bits & bloom bits) */
322 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
323 /* jump to next tag if it does not match */
324 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
326 /* load device bloom bits in A */
327 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo));
328 /* clear bits (tag bits & bloom bits) */
329 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
330 /* jump behind end of tag match block if tag matches */
332 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
335 /* nothing matched, drop packet */
336 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
339 /* add all subsystem matches */
340 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) {
341 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
342 unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry));
344 /* load device subsystem value in A */
345 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash));
346 if (udev_list_entry_get_value(list_entry) == NULL) {
347 /* jump if subsystem does not match */
348 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
350 /* jump if subsystem does not match */
351 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
353 /* load device devtype value in A */
354 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash));
355 /* jump if value does not match */
356 hash = util_string_hash32(udev_list_entry_get_value(list_entry));
357 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
360 /* matched, pass packet */
361 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
363 if (i+1 >= ELEMENTSOF(ins))
367 /* nothing matched, drop packet */
368 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
371 /* matched, pass packet */
372 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
375 memset(&filter, 0x00, sizeof(filter));
378 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
379 return err < 0 ? -errno : 0;
382 int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
384 udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid;
388 * udev_monitor_enable_receiving:
389 * @udev_monitor: the monitor which should receive events
391 * Binds the @udev_monitor socket to the event source.
393 * Returns: 0 on success, otherwise a negative error value.
395 _public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
400 udev_monitor_filter_update(udev_monitor);
402 if (!udev_monitor->bound) {
403 err = bind(udev_monitor->sock,
404 &udev_monitor->snl.sa, sizeof(struct sockaddr_nl));
406 udev_monitor->bound = true;
410 union sockaddr_union snl;
414 * get the address the kernel has assigned us
415 * it is usually, but not necessarily the pid
417 addrlen = sizeof(struct sockaddr_nl);
418 err = getsockname(udev_monitor->sock, &snl.sa, &addrlen);
420 udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid;
422 udev_err(udev_monitor->udev, "bind failed: %m\n");
426 /* enable receiving of sender credentials */
427 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
432 * udev_monitor_set_receive_buffer_size:
433 * @udev_monitor: the monitor which should receive events
434 * @size: the size in bytes
436 * Set the size of the kernel socket buffer. This call needs the
437 * appropriate privileges to succeed.
439 * Returns: 0 on success, otherwise -1 on error.
441 _public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
443 if (udev_monitor == NULL)
445 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
448 int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
452 err = close(udev_monitor->sock);
453 udev_monitor->sock = -1;
454 return err < 0 ? -errno : 0;
459 * @udev_monitor: udev monitor
461 * Take a reference of a udev monitor.
463 * Returns: the passed udev monitor
465 _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
467 if (udev_monitor == NULL)
469 udev_monitor->refcount++;
474 * udev_monitor_unref:
475 * @udev_monitor: udev monitor
477 * Drop a reference of a udev monitor. If the refcount reaches zero,
478 * the bound socket will be closed, and the resources of the monitor
483 _public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor)
485 if (udev_monitor == NULL)
487 udev_monitor->refcount--;
488 if (udev_monitor->refcount > 0)
490 if (udev_monitor->sock >= 0)
491 close(udev_monitor->sock);
492 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
493 udev_list_cleanup(&udev_monitor->filter_tag_list);
499 * udev_monitor_get_udev:
500 * @udev_monitor: udev monitor
502 * Retrieve the udev library context the monitor was created with.
504 * Returns: the udev library context
506 _public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
508 if (udev_monitor == NULL)
510 return udev_monitor->udev;
514 * udev_monitor_get_fd:
515 * @udev_monitor: udev monitor
517 * Retrieve the socket file descriptor associated with the monitor.
519 * Returns: the socket file descriptor
521 _public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
523 if (udev_monitor == NULL)
525 return udev_monitor->sock;
528 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
530 struct udev_list_entry *list_entry;
532 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
534 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
535 const char *subsys = udev_list_entry_get_name(list_entry);
536 const char *dsubsys = udev_device_get_subsystem(udev_device);
538 const char *ddevtype;
540 if (!streq(dsubsys, subsys))
543 devtype = udev_list_entry_get_value(list_entry);
546 ddevtype = udev_device_get_devtype(udev_device);
547 if (ddevtype == NULL)
549 if (streq(ddevtype, devtype))
555 if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
557 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
558 const char *tag = udev_list_entry_get_name(list_entry);
560 if (udev_device_has_tag(udev_device, tag))
567 * udev_monitor_receive_device:
568 * @udev_monitor: udev monitor
570 * Receive data from the udev monitor socket, allocate a new udev
571 * device, fill in the received data, and return the device.
573 * Only socket connections with uid=0 are accepted.
575 * The monitor socket is by default set to NONBLOCK. A variant of poll() on
576 * the file descriptor returned by udev_monitor_get_fd() should to be used to
577 * wake up when new devices arrive, or alternatively the file descriptor
578 * switched into blocking mode.
580 * The initial refcount is 1, and needs to be decremented to
581 * release the resources of the udev device.
583 * Returns: a new udev device, or #NULL, in case of an error
585 _public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
587 struct udev_device *udev_device;
590 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
591 struct cmsghdr *cmsg;
592 union sockaddr_union snl;
599 if (udev_monitor == NULL)
602 iov.iov_len = sizeof(buf);
603 memset (&smsg, 0x00, sizeof(struct msghdr));
606 smsg.msg_control = cred_msg;
607 smsg.msg_controllen = sizeof(cred_msg);
608 smsg.msg_name = &snl;
609 smsg.msg_namelen = sizeof(snl);
611 buflen = recvmsg(udev_monitor->sock, &smsg, 0);
614 udev_dbg(udev_monitor->udev, "unable to receive message\n");
618 if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
619 udev_dbg(udev_monitor->udev, "invalid message length\n");
623 if (snl.nl.nl_groups == 0) {
624 /* unicast message, check if we trust the sender */
625 if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 ||
626 snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) {
627 udev_dbg(udev_monitor->udev, "unicast netlink message ignored\n");
630 } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) {
631 if (snl.nl.nl_pid > 0) {
632 udev_dbg(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
638 cmsg = CMSG_FIRSTHDR(&smsg);
639 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
640 udev_dbg(udev_monitor->udev, "no sender credentials received, message ignored\n");
644 cred = (struct ucred *)CMSG_DATA(cmsg);
645 if (cred->uid != 0) {
646 udev_dbg(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
650 udev_device = udev_device_new(udev_monitor->udev);
651 if (udev_device == NULL)
654 if (memcmp(buf, "libudev", 8) == 0) {
655 struct udev_monitor_netlink_header *nlh;
657 /* udev message needs proper version magic */
658 nlh = (struct udev_monitor_netlink_header *) buf;
659 if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) {
660 udev_err(udev_monitor->udev, "unrecognized message signature (%x != %x)\n",
661 nlh->magic, htonl(UDEV_MONITOR_MAGIC));
662 udev_device_unref(udev_device);
665 if (nlh->properties_off+32 > (size_t)buflen) {
666 udev_device_unref(udev_device);
670 bufpos = nlh->properties_off;
672 /* devices received from udev are always initialized */
673 udev_device_set_is_initialized(udev_device);
675 /* kernel message with header */
676 bufpos = strlen(buf) + 1;
677 if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
678 udev_dbg(udev_monitor->udev, "invalid message length\n");
679 udev_device_unref(udev_device);
683 /* check message header */
684 if (strstr(buf, "@/") == NULL) {
685 udev_dbg(udev_monitor->udev, "unrecognized message header\n");
686 udev_device_unref(udev_device);
691 udev_device_set_info_loaded(udev_device);
693 while (bufpos < buflen) {
698 keylen = strlen(key);
701 bufpos += keylen + 1;
702 udev_device_add_property_from_string_parse(udev_device, key);
705 if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
706 udev_dbg(udev_monitor->udev, "missing values, invalid device\n");
707 udev_device_unref(udev_device);
711 /* skip device, if it does not pass the current filter */
712 if (!passes_filter(udev_monitor, udev_device)) {
713 struct pollfd pfd[1];
716 udev_device_unref(udev_device);
718 /* if something is queued, get next device */
719 pfd[0].fd = udev_monitor->sock;
720 pfd[0].events = POLLIN;
721 rc = poll(pfd, 1, 0);
730 int udev_monitor_send_device(struct udev_monitor *udev_monitor,
731 struct udev_monitor *destination, struct udev_device *udev_device)
739 struct udev_monitor_netlink_header nlh;
740 struct udev_list_entry *list_entry;
741 uint64_t tag_bloom_bits;
743 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
747 /* add versioned header */
748 memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
749 memcpy(nlh.prefix, "libudev", 8);
750 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
751 nlh.header_size = sizeof(struct udev_monitor_netlink_header);
752 val = udev_device_get_subsystem(udev_device);
753 nlh.filter_subsystem_hash = htonl(util_string_hash32(val));
754 val = udev_device_get_devtype(udev_device);
756 nlh.filter_devtype_hash = htonl(util_string_hash32(val));
757 iov[0].iov_base = &nlh;
758 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
760 /* add tag bloom filter */
762 udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
763 tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry));
764 if (tag_bloom_bits > 0) {
765 nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32);
766 nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff);
769 /* add properties list */
770 nlh.properties_off = iov[0].iov_len;
771 nlh.properties_len = blen;
772 iov[1].iov_base = (char *)buf;
773 iov[1].iov_len = blen;
775 memset(&smsg, 0x00, sizeof(struct msghdr));
779 * Use custom address for target, or the default one.
781 * If we send to a multicast group, we will get
782 * ECONNREFUSED, which is expected.
784 if (destination != NULL)
785 smsg.msg_name = &destination->snl;
787 smsg.msg_name = &udev_monitor->snl_destination;
788 smsg.msg_namelen = sizeof(struct sockaddr_nl);
789 count = sendmsg(udev_monitor->sock, &smsg, 0);
790 udev_dbg(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor);
795 * udev_monitor_filter_add_match_subsystem_devtype:
796 * @udev_monitor: the monitor
797 * @subsystem: the subsystem value to match the incoming devices against
798 * @devtype: the devtype value to match the incoming devices against
800 * This filter is efficiently executed inside the kernel, and libudev subscribers
801 * will usually not be woken up for devices which do not match.
803 * The filter must be installed before the monitor is switched to listening mode.
805 * Returns: 0 on success, otherwise a negative error value.
807 _public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
809 if (udev_monitor == NULL)
811 if (subsystem == NULL)
813 if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL)
819 * udev_monitor_filter_add_match_tag:
820 * @udev_monitor: the monitor
821 * @tag: the name of a tag
823 * This filter is efficiently executed inside the kernel, and libudev subscribers
824 * will usually not be woken up for devices which do not match.
826 * The filter must be installed before the monitor is switched to listening mode.
828 * Returns: 0 on success, otherwise a negative error value.
830 _public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
832 if (udev_monitor == NULL)
836 if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL)
842 * udev_monitor_filter_remove:
843 * @udev_monitor: monitor
845 * Remove all filters from monitor.
847 * Returns: 0 on success, otherwise a negative error value.
849 _public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
851 static struct sock_fprog filter = { 0, NULL };
853 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
854 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));