2 * libudev - interface to udev device information
4 * Copyright (C) 2008-2010 Kay Sievers <kay.sievers@vrfy.org>
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
21 #include <sys/socket.h>
23 #include <arpa/inet.h>
24 #include <linux/netlink.h>
25 #include <linux/filter.h>
28 #include "libudev-private.h"
31 * SECTION:libudev-monitor
32 * @short_description: device event source
34 * Connects to a device event source.
40 * Opaque object handling one event source.
46 struct sockaddr_nl snl;
47 struct sockaddr_nl snl_trusted_sender;
48 struct sockaddr_nl snl_destination;
49 struct sockaddr_un sun;
51 struct udev_list_node filter_subsystem_list;
52 struct udev_list_node filter_tag_list;
56 enum udev_monitor_netlink_group {
62 #define UDEV_MONITOR_MAGIC 0xfeedcafe
63 struct udev_monitor_netlink_header {
64 /* "libudev" prefix to distinguish libudev and kernel messages */
67 * magic to protect against daemon <-> library message format mismatch
68 * used in the kernel from socket filter rules; needs to be stored in network order
71 /* total length of header structure known to the sender */
72 unsigned int header_size;
73 /* properties string buffer */
74 unsigned int properties_off;
75 unsigned int properties_len;
77 * hashes of primary device properties strings, to let libudev subscribers
78 * use in-kernel socket filters; values need to be stored in network order
80 unsigned int filter_subsystem_hash;
81 unsigned int filter_devtype_hash;
82 unsigned int filter_tag_bloom_hi;
83 unsigned int filter_tag_bloom_lo;
86 static struct udev_monitor *udev_monitor_new(struct udev *udev)
88 struct udev_monitor *udev_monitor;
90 udev_monitor = calloc(1, sizeof(struct udev_monitor));
91 if (udev_monitor == NULL)
93 udev_monitor->refcount = 1;
94 udev_monitor->udev = udev;
95 udev_list_init(&udev_monitor->filter_subsystem_list);
96 udev_list_init(&udev_monitor->filter_tag_list);
101 * udev_monitor_new_from_socket:
102 * @udev: udev library context
103 * @socket_path: unix socket path
105 * Create new udev monitor and connect to a specified socket. The
106 * path to a socket either points to an existing socket file, or if
107 * the socket path starts with a '@' character, an abstract namespace
108 * socket will be used.
110 * A socket file will not be created. If it does not already exist,
111 * it will fall-back and connect to an abstract namespace socket with
112 * the given path. The permissions adjustment of a socket file, as
113 * well as the later cleanup, needs to be done by the caller.
115 * The initial refcount is 1, and needs to be decremented to
116 * release the resources of the udev monitor.
118 * Returns: a new udev monitor, or #NULL, in case of an error
120 UDEV_EXPORT struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
122 struct udev_monitor *udev_monitor;
127 if (socket_path == NULL)
129 udev_monitor = udev_monitor_new(udev);
130 if (udev_monitor == NULL)
133 udev_monitor->sun.sun_family = AF_LOCAL;
134 if (socket_path[0] == '@') {
135 /* translate leading '@' to abstract namespace */
136 util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
137 udev_monitor->sun.sun_path[0] = '\0';
138 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
139 } else if (stat(socket_path, &statbuf) == 0 && S_ISSOCK(statbuf.st_mode)) {
140 /* existing socket file */
141 util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
142 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
144 /* no socket file, assume abstract namespace socket */
145 util_strscpy(&udev_monitor->sun.sun_path[1], sizeof(udev_monitor->sun.sun_path)-1, socket_path);
146 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path)+1;
148 udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
149 if (udev_monitor->sock == -1) {
150 err(udev, "error getting socket: %m\n");
155 dbg(udev, "monitor %p created with '%s'\n", udev_monitor, socket_path);
159 struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
161 struct udev_monitor *udev_monitor;
168 group = UDEV_MONITOR_NONE;
169 else if (strcmp(name, "udev") == 0)
170 group = UDEV_MONITOR_UDEV;
171 else if (strcmp(name, "kernel") == 0)
172 group = UDEV_MONITOR_KERNEL;
176 udev_monitor = udev_monitor_new(udev);
177 if (udev_monitor == NULL)
181 udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
182 if (udev_monitor->sock == -1) {
183 err(udev, "error getting socket: %m\n");
188 udev_monitor->bound = true;
189 udev_monitor->sock = fd;
192 udev_monitor->snl.nl_family = AF_NETLINK;
193 udev_monitor->snl.nl_groups = group;
195 /* default destination for sending */
196 udev_monitor->snl_destination.nl_family = AF_NETLINK;
197 udev_monitor->snl_destination.nl_groups = UDEV_MONITOR_UDEV;
199 dbg(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT (%u)\n", udev_monitor, group);
204 * udev_monitor_new_from_netlink:
205 * @udev: udev library context
206 * @name: name of event source
208 * Create new udev monitor and connect to a specified event
209 * source. Valid sources identifiers are "udev" and "kernel".
211 * Applications should usually not connect directly to the
212 * "kernel" events, because the devices might not be useable
213 * at that time, before udev has configured them, and created
216 * Accessing devices at the same time as udev, might result
217 * in unpredictable behavior.
219 * The "udev" events are sent out after udev has finished its
220 * event processing, all rules have been processed, and needed
221 * device nodes are created.
223 * The initial refcount is 1, and needs to be decremented to
224 * release the resources of the udev monitor.
226 * Returns: a new udev monitor, or #NULL, in case of an error
228 UDEV_EXPORT struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
230 return udev_monitor_new_from_netlink_fd(udev, name, -1);
233 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
234 unsigned short code, unsigned int data)
236 struct sock_filter *ins = &inss[*i];
243 static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
244 unsigned short code, unsigned int data,
245 unsigned short jt, unsigned short jf)
247 struct sock_filter *ins = &inss[*i];
257 * udev_monitor_filter_update:
258 * @udev_monitor: monitor
260 * Update the installed filter. This might only be needed, if the filter was removed or changed.
262 * Returns: 0 on success, otherwise a negative error value.
264 UDEV_EXPORT int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
266 struct sock_filter ins[512];
267 struct sock_fprog filter;
269 struct udev_list_entry *list_entry;
272 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL &&
273 udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
276 memset(ins, 0x00, sizeof(ins));
279 /* load magic in A */
280 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
281 /* jump if magic matches */
282 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
283 /* wrong magic, pass packet */
284 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
286 if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) {
289 /* count tag matches, to calculate end of tag match block */
291 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list))
294 /* add all tags matches */
295 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
296 uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry));
297 uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
298 uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
300 /* load device bloom bits in A */
301 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi));
302 /* clear bits (tag bits & bloom bits) */
303 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
304 /* jump to next tag if it does not match */
305 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
307 /* load device bloom bits in A */
308 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo));
309 /* clear bits (tag bits & bloom bits) */
310 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
311 /* jump behind end of tag match block if tag matches */
313 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
316 /* nothing matched, drop packet */
317 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
320 /* add all subsystem matches */
321 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) {
322 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
323 unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry));
325 /* load device subsystem value in A */
326 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash));
327 if (udev_list_entry_get_value(list_entry) == NULL) {
328 /* jump if subsystem does not match */
329 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
331 /* jump if subsystem does not match */
332 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
334 /* load device devtype value in A */
335 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash));
336 /* jump if value does not match */
337 hash = util_string_hash32(udev_list_entry_get_value(list_entry));
338 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
341 /* matched, pass packet */
342 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
344 if (i+1 >= ARRAY_SIZE(ins))
348 /* nothing matched, drop packet */
349 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
352 /* matched, pass packet */
353 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
356 memset(&filter, 0x00, sizeof(filter));
359 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
363 int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
365 udev_monitor->snl_trusted_sender.nl_pid = sender->snl.nl_pid;
369 * udev_monitor_enable_receiving:
370 * @udev_monitor: the monitor which should receive events
372 * Binds the @udev_monitor socket to the event source.
374 * Returns: 0 on success, otherwise a negative error value.
376 UDEV_EXPORT int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
381 if (udev_monitor->sun.sun_family != 0) {
382 if (!udev_monitor->bound) {
383 err = bind(udev_monitor->sock,
384 (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
386 udev_monitor->bound = true;
388 } else if (udev_monitor->snl.nl_family != 0) {
389 udev_monitor_filter_update(udev_monitor);
390 if (!udev_monitor->bound) {
391 err = bind(udev_monitor->sock,
392 (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
394 udev_monitor->bound = true;
397 struct sockaddr_nl snl;
401 * get the address the kernel has assigned us
402 * it is usually, but not necessarily the pid
404 addrlen = sizeof(struct sockaddr_nl);
405 err = getsockname(udev_monitor->sock, (struct sockaddr *)&snl, &addrlen);
407 udev_monitor->snl.nl_pid = snl.nl_pid;
414 err(udev_monitor->udev, "bind failed: %m\n");
418 /* enable receiving of sender credentials */
419 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
424 * udev_monitor_set_receive_buffer_size:
425 * @udev_monitor: the monitor which should receive events
426 * @size: the size in bytes
428 * Set the size of the kernel socket buffer. This call needs the
429 * appropriate privileges to succeed.
431 * Returns: 0 on success, otherwise -1 on error.
433 UDEV_EXPORT int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
435 if (udev_monitor == NULL)
437 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
440 int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
444 err = close(udev_monitor->sock);
445 udev_monitor->sock = -1;
451 * @udev_monitor: udev monitor
453 * Take a reference of a udev monitor.
455 * Returns: the passed udev monitor
457 UDEV_EXPORT struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
459 if (udev_monitor == NULL)
461 udev_monitor->refcount++;
466 * udev_monitor_unref:
467 * @udev_monitor: udev monitor
469 * Drop a reference of a udev monitor. If the refcount reaches zero,
470 * the bound socket will be closed, and the resources of the monitor
474 UDEV_EXPORT void udev_monitor_unref(struct udev_monitor *udev_monitor)
476 if (udev_monitor == NULL)
478 udev_monitor->refcount--;
479 if (udev_monitor->refcount > 0)
481 if (udev_monitor->sock >= 0)
482 close(udev_monitor->sock);
483 udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
484 udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_tag_list);
485 dbg(udev_monitor->udev, "monitor %p released\n", udev_monitor);
490 * udev_monitor_get_udev:
491 * @udev_monitor: udev monitor
493 * Retrieve the udev library context the monitor was created with.
495 * Returns: the udev library context
497 UDEV_EXPORT struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
499 if (udev_monitor == NULL)
501 return udev_monitor->udev;
505 * udev_monitor_get_fd:
506 * @udev_monitor: udev monitor
508 * Retrieve the socket file descriptor associated with the monitor.
510 * Returns: the socket file descriptor
512 UDEV_EXPORT int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
514 if (udev_monitor == NULL)
516 return udev_monitor->sock;
519 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
521 struct udev_list_entry *list_entry;
523 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
525 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
526 const char *subsys = udev_list_entry_get_name(list_entry);
527 const char *dsubsys = udev_device_get_subsystem(udev_device);
529 const char *ddevtype;
531 if (strcmp(dsubsys, subsys) != 0)
534 devtype = udev_list_entry_get_value(list_entry);
537 ddevtype = udev_device_get_devtype(udev_device);
538 if (ddevtype == NULL)
540 if (strcmp(ddevtype, devtype) == 0)
546 if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
548 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
549 const char *tag = udev_list_entry_get_name(list_entry);
551 if (udev_device_has_tag(udev_device, tag))
558 * udev_monitor_receive_device:
559 * @udev_monitor: udev monitor
561 * Receive data from the udev monitor socket, allocate a new udev
562 * device, fill in the received data, and return the device.
564 * Only socket connections with uid=0 are accepted. The caller
565 * needs to make sure that there is data to read from the socket.
566 * The call will block until the socket becomes readable.
568 * The initial refcount is 1, and needs to be decremented to
569 * release the resources of the udev device.
571 * Returns: a new udev device, or #NULL, in case of an error
573 UDEV_EXPORT struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
575 struct udev_device *udev_device;
578 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
579 struct cmsghdr *cmsg;
580 struct sockaddr_nl snl;
585 struct udev_monitor_netlink_header *nlh;
588 if (udev_monitor == NULL)
590 memset(buf, 0x00, sizeof(buf));
592 iov.iov_len = sizeof(buf);
593 memset (&smsg, 0x00, sizeof(struct msghdr));
596 smsg.msg_control = cred_msg;
597 smsg.msg_controllen = sizeof(cred_msg);
599 if (udev_monitor->snl.nl_family != 0) {
600 smsg.msg_name = &snl;
601 smsg.msg_namelen = sizeof(snl);
604 buflen = recvmsg(udev_monitor->sock, &smsg, 0);
607 info(udev_monitor->udev, "unable to receive message\n");
611 if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
612 info(udev_monitor->udev, "invalid message length\n");
616 if (udev_monitor->snl.nl_family != 0) {
617 if (snl.nl_groups == 0) {
618 /* unicast message, check if we trust the sender */
619 if (udev_monitor->snl_trusted_sender.nl_pid == 0 ||
620 snl.nl_pid != udev_monitor->snl_trusted_sender.nl_pid) {
621 info(udev_monitor->udev, "unicast netlink message ignored\n");
624 } else if (snl.nl_groups == UDEV_MONITOR_KERNEL) {
625 if (snl.nl_pid > 0) {
626 info(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
633 cmsg = CMSG_FIRSTHDR(&smsg);
634 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
635 info(udev_monitor->udev, "no sender credentials received, message ignored\n");
639 cred = (struct ucred *)CMSG_DATA(cmsg);
640 if (cred->uid != 0) {
641 info(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
645 if (memcmp(buf, "libudev", 8) == 0) {
646 /* udev message needs proper version magic */
647 nlh = (struct udev_monitor_netlink_header *) buf;
648 if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) {
649 err(udev_monitor->udev, "ignored a message from an invalid release of udevadm (%x != %x)\n",
650 nlh->magic, htonl(UDEV_MONITOR_MAGIC));
653 if (nlh->properties_off+32 > buflen)
655 bufpos = nlh->properties_off;
657 /* kernel message with header */
658 bufpos = strlen(buf) + 1;
659 if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
660 info(udev_monitor->udev, "invalid message length\n");
664 /* check message header */
665 if (strstr(buf, "@/") == NULL) {
666 info(udev_monitor->udev, "unrecognized message header\n");
671 udev_device = udev_device_new(udev_monitor->udev);
672 if (udev_device == NULL)
674 udev_device_set_info_loaded(udev_device);
676 while (bufpos < buflen) {
681 keylen = strlen(key);
684 bufpos += keylen + 1;
685 udev_device_add_property_from_string_parse(udev_device, key);
688 if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
689 info(udev_monitor->udev, "missing values, invalid device\n");
690 udev_device_unref(udev_device);
694 /* skip device, if it does not pass the current filter */
695 if (!passes_filter(udev_monitor, udev_device)) {
696 struct pollfd pfd[1];
699 udev_device_unref(udev_device);
701 /* if something is queued, get next device */
702 pfd[0].fd = udev_monitor->sock;
703 pfd[0].events = POLLIN;
704 rc = poll(pfd, 1, 0);
713 int udev_monitor_send_device(struct udev_monitor *udev_monitor,
714 struct udev_monitor *destination, struct udev_device *udev_device)
720 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
724 if (udev_monitor->sun.sun_family != 0) {
731 /* header <action>@<devpath> */
732 action = udev_device_get_action(udev_device);
736 if (util_strpcpyl(&s, sizeof(header), action, "@", udev_device_get_devpath(udev_device), NULL) == 0)
738 iov[0].iov_base = header;
739 iov[0].iov_len = (s - header)+1;
741 /* add properties list */
742 iov[1].iov_base = (char *)buf;
743 iov[1].iov_len = blen;
745 memset(&smsg, 0x00, sizeof(struct msghdr));
748 smsg.msg_name = &udev_monitor->sun;
749 smsg.msg_namelen = udev_monitor->addrlen;
750 count = sendmsg(udev_monitor->sock, &smsg, 0);
751 info(udev_monitor->udev, "passed %zi bytes to socket monitor %p\n", count, udev_monitor);
755 if (udev_monitor->snl.nl_family != 0) {
759 struct udev_monitor_netlink_header nlh;
760 struct udev_list_entry *list_entry;
761 uint64_t tag_bloom_bits;
763 /* add versioned header */
764 memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
765 memcpy(nlh.prefix, "libudev", 8);
766 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
767 nlh.header_size = sizeof(struct udev_monitor_netlink_header);
768 val = udev_device_get_subsystem(udev_device);
769 nlh.filter_subsystem_hash = htonl(util_string_hash32(val));
770 val = udev_device_get_devtype(udev_device);
772 nlh.filter_devtype_hash = htonl(util_string_hash32(val));
773 iov[0].iov_base = &nlh;
774 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
776 /* add tag bloom filter */
778 udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
779 tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry));
780 if (tag_bloom_bits > 0) {
781 nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32);
782 nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff);
785 /* add properties list */
786 nlh.properties_off = iov[0].iov_len;
787 nlh.properties_len = blen;
788 iov[1].iov_base = (char *)buf;
789 iov[1].iov_len = blen;
791 memset(&smsg, 0x00, sizeof(struct msghdr));
795 * Use custom address for target, or the default one.
797 * If we send to a multicast group, we will get
798 * ECONNREFUSED, which is expected.
800 if (destination != NULL)
801 smsg.msg_name = &destination->snl;
803 smsg.msg_name = &udev_monitor->snl_destination;
804 smsg.msg_namelen = sizeof(struct sockaddr_nl);
805 count = sendmsg(udev_monitor->sock, &smsg, 0);
806 info(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor);
814 * udev_monitor_filter_add_match_subsystem_devtype:
815 * @udev_monitor: the monitor
816 * @subsystem: the subsystem value to match the incoming devices against
817 * @devtype: the devtype value to match the incoming devices against
819 * This filer is efficiently executed inside the kernel, and libudev subscribers
820 * will usually not be woken up for devices which do not match.
822 * The filter must be installed before the monitor is switched to listening mode.
824 * Returns: 0 on success, otherwise a negative error value.
826 UDEV_EXPORT int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
828 if (udev_monitor == NULL)
830 if (subsystem == NULL)
832 if (udev_list_entry_add(udev_monitor->udev,
833 &udev_monitor->filter_subsystem_list, subsystem, devtype, 0) == NULL)
839 * udev_monitor_filter_add_match_tag:
840 * @udev_monitor: the monitor
841 * @tag: the name of a tag
843 * This filer is efficiently executed inside the kernel, and libudev subscribers
844 * will usually not be woken up for devices which do not match.
846 * The filter must be installed before the monitor is switched to listening mode.
848 * Returns: 0 on success, otherwise a negative error value.
850 UDEV_EXPORT int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
852 if (udev_monitor == NULL)
856 if (udev_list_entry_add(udev_monitor->udev,
857 &udev_monitor->filter_tag_list, tag, NULL, 0) == NULL)
863 * udev_monitor_filter_remove:
864 * @udev_monitor: monitor
866 * Remove all filters from monitor.
868 * Returns: 0 on success, otherwise a negative error value.
870 UDEV_EXPORT int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
872 static struct sock_fprog filter = { 0, NULL };
874 udev_list_cleanup_entries(udev_monitor->udev, &udev_monitor->filter_subsystem_list);
875 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));