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 an 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 filter_subsystem_list;
52 struct udev_list 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, &udev_monitor->filter_subsystem_list, false);
96 udev_list_init(udev, &udev_monitor->filter_tag_list, true);
101 * udev_monitor_new_from_socket:
102 * @udev: udev library context
103 * @socket_path: unix socket path
105 * This function should not be used in any new application. The
106 * kernel's netlink socket multiplexes messages to all interested
107 * clients. Creating custom sockets from udev to applications
110 * Create a new udev monitor and connect to a specified socket. The
111 * path to a socket either points to an existing socket file, or if
112 * the socket path starts with a '@' character, an abstract namespace
113 * socket will be used.
115 * A socket file will not be created. If it does not already exist,
116 * it will fall-back and connect to an abstract namespace socket with
117 * the given path. The permissions adjustment of a socket file, as
118 * well as the later cleanup, needs to be done by the caller.
120 * The initial refcount is 1, and needs to be decremented to
121 * release the resources of the udev monitor.
123 * Returns: a new udev monitor, or #NULL, in case of an error
125 _public_ struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
127 struct udev_monitor *udev_monitor;
132 if (socket_path == NULL)
134 udev_monitor = udev_monitor_new(udev);
135 if (udev_monitor == NULL)
138 udev_monitor->sun.sun_family = AF_LOCAL;
139 if (socket_path[0] == '@') {
140 /* translate leading '@' to abstract namespace */
141 util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
142 udev_monitor->sun.sun_path[0] = '\0';
143 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
144 } else if (stat(socket_path, &statbuf) == 0 && S_ISSOCK(statbuf.st_mode)) {
145 /* existing socket file */
146 util_strscpy(udev_monitor->sun.sun_path, sizeof(udev_monitor->sun.sun_path), socket_path);
147 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path);
149 /* no socket file, assume abstract namespace socket */
150 util_strscpy(&udev_monitor->sun.sun_path[1], sizeof(udev_monitor->sun.sun_path)-1, socket_path);
151 udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path)+1;
153 udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
154 if (udev_monitor->sock == -1) {
155 err(udev, "error getting socket: %m\n");
163 struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
165 struct udev_monitor *udev_monitor;
172 group = UDEV_MONITOR_NONE;
173 else if (strcmp(name, "udev") == 0)
174 group = UDEV_MONITOR_UDEV;
175 else if (strcmp(name, "kernel") == 0)
176 group = UDEV_MONITOR_KERNEL;
180 udev_monitor = udev_monitor_new(udev);
181 if (udev_monitor == NULL)
185 udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
186 if (udev_monitor->sock == -1) {
187 err(udev, "error getting socket: %m\n");
192 udev_monitor->bound = true;
193 udev_monitor->sock = fd;
196 udev_monitor->snl.nl_family = AF_NETLINK;
197 udev_monitor->snl.nl_groups = group;
199 /* default destination for sending */
200 udev_monitor->snl_destination.nl_family = AF_NETLINK;
201 udev_monitor->snl_destination.nl_groups = UDEV_MONITOR_UDEV;
207 * udev_monitor_new_from_netlink:
208 * @udev: udev library context
209 * @name: name of event source
211 * Create new udev monitor and connect to a specified event
212 * source. Valid sources identifiers are "udev" and "kernel".
214 * Applications should usually not connect directly to the
215 * "kernel" events, because the devices might not be useable
216 * at that time, before udev has configured them, and created
217 * device nodes. Accessing devices at the same time as udev,
218 * might result in unpredictable behavior. The "udev" events
219 * are sent out after udev has finished its event processing,
220 * all rules have been processed, and needed device nodes are
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 _public_ 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 socket filter. This is only needed,
261 * if the filter was removed or changed.
263 * Returns: 0 on success, otherwise a negative error value.
265 _public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
267 struct sock_filter ins[512];
268 struct sock_fprog filter;
270 struct udev_list_entry *list_entry;
273 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL &&
274 udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
277 memset(ins, 0x00, sizeof(ins));
280 /* load magic in A */
281 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
282 /* jump if magic matches */
283 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
284 /* wrong magic, pass packet */
285 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
287 if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) {
290 /* count tag matches, to calculate end of tag match block */
292 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list))
295 /* add all tags matches */
296 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
297 uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry));
298 uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
299 uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
301 /* load device bloom bits in A */
302 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi));
303 /* clear bits (tag bits & bloom bits) */
304 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
305 /* jump to next tag if it does not match */
306 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
308 /* load device bloom bits in A */
309 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo));
310 /* clear bits (tag bits & bloom bits) */
311 bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
312 /* jump behind end of tag match block if tag matches */
314 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
317 /* nothing matched, drop packet */
318 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
321 /* add all subsystem matches */
322 if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) {
323 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
324 unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry));
326 /* load device subsystem value in A */
327 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash));
328 if (udev_list_entry_get_value(list_entry) == NULL) {
329 /* jump if subsystem does not match */
330 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
332 /* jump if subsystem does not match */
333 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
335 /* load device devtype value in A */
336 bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash));
337 /* jump if value does not match */
338 hash = util_string_hash32(udev_list_entry_get_value(list_entry));
339 bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
342 /* matched, pass packet */
343 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
345 if (i+1 >= ARRAY_SIZE(ins))
349 /* nothing matched, drop packet */
350 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
353 /* matched, pass packet */
354 bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
357 memset(&filter, 0x00, sizeof(filter));
360 err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
364 int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
366 udev_monitor->snl_trusted_sender.nl_pid = sender->snl.nl_pid;
370 * udev_monitor_enable_receiving:
371 * @udev_monitor: the monitor which should receive events
373 * Binds the @udev_monitor socket to the event source.
375 * Returns: 0 on success, otherwise a negative error value.
377 _public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
382 if (udev_monitor->sun.sun_family != 0) {
383 if (!udev_monitor->bound) {
384 err = bind(udev_monitor->sock,
385 (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
387 udev_monitor->bound = true;
389 } else if (udev_monitor->snl.nl_family != 0) {
390 udev_monitor_filter_update(udev_monitor);
391 if (!udev_monitor->bound) {
392 err = bind(udev_monitor->sock,
393 (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
395 udev_monitor->bound = true;
398 struct sockaddr_nl snl;
402 * get the address the kernel has assigned us
403 * it is usually, but not necessarily the pid
405 addrlen = sizeof(struct sockaddr_nl);
406 err = getsockname(udev_monitor->sock, (struct sockaddr *)&snl, &addrlen);
408 udev_monitor->snl.nl_pid = snl.nl_pid;
415 err(udev_monitor->udev, "bind failed: %m\n");
419 /* enable receiving of sender credentials */
420 setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
425 * udev_monitor_set_receive_buffer_size:
426 * @udev_monitor: the monitor which should receive events
427 * @size: the size in bytes
429 * Set the size of the kernel socket buffer. This call needs the
430 * appropriate privileges to succeed.
432 * Returns: 0 on success, otherwise -1 on error.
434 _public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
436 if (udev_monitor == NULL)
438 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
441 int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
445 err = close(udev_monitor->sock);
446 udev_monitor->sock = -1;
452 * @udev_monitor: udev monitor
454 * Take a reference of a udev monitor.
456 * Returns: the passed udev monitor
458 _public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
460 if (udev_monitor == NULL)
462 udev_monitor->refcount++;
467 * udev_monitor_unref:
468 * @udev_monitor: udev monitor
470 * Drop a reference of a udev monitor. If the refcount reaches zero,
471 * the bound socket will be closed, and the resources of the monitor
475 _public_ void udev_monitor_unref(struct udev_monitor *udev_monitor)
477 if (udev_monitor == NULL)
479 udev_monitor->refcount--;
480 if (udev_monitor->refcount > 0)
482 if (udev_monitor->sock >= 0)
483 close(udev_monitor->sock);
484 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
485 udev_list_cleanup(&udev_monitor->filter_tag_list);
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 _public_ 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 _public_ 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.
566 * The initial refcount is 1, and needs to be decremented to
567 * release the resources of the udev device.
569 * Returns: a new udev device, or #NULL, in case of an error
571 _public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
573 struct udev_device *udev_device;
576 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
577 struct cmsghdr *cmsg;
578 struct sockaddr_nl snl;
583 struct udev_monitor_netlink_header *nlh;
586 if (udev_monitor == NULL)
589 iov.iov_len = sizeof(buf);
590 memset (&smsg, 0x00, sizeof(struct msghdr));
593 smsg.msg_control = cred_msg;
594 smsg.msg_controllen = sizeof(cred_msg);
596 if (udev_monitor->snl.nl_family != 0) {
597 smsg.msg_name = &snl;
598 smsg.msg_namelen = sizeof(snl);
601 buflen = recvmsg(udev_monitor->sock, &smsg, 0);
604 dbg(udev_monitor->udev, "unable to receive message\n");
608 if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
609 dbg(udev_monitor->udev, "invalid message length\n");
613 if (udev_monitor->snl.nl_family != 0) {
614 if (snl.nl_groups == 0) {
615 /* unicast message, check if we trust the sender */
616 if (udev_monitor->snl_trusted_sender.nl_pid == 0 ||
617 snl.nl_pid != udev_monitor->snl_trusted_sender.nl_pid) {
618 dbg(udev_monitor->udev, "unicast netlink message ignored\n");
621 } else if (snl.nl_groups == UDEV_MONITOR_KERNEL) {
622 if (snl.nl_pid > 0) {
623 dbg(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
630 cmsg = CMSG_FIRSTHDR(&smsg);
631 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
632 dbg(udev_monitor->udev, "no sender credentials received, message ignored\n");
636 cred = (struct ucred *)CMSG_DATA(cmsg);
637 if (cred->uid != 0) {
638 dbg(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
642 if (memcmp(buf, "libudev", 8) == 0) {
643 /* udev message needs proper version magic */
644 nlh = (struct udev_monitor_netlink_header *) buf;
645 if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) {
646 err(udev_monitor->udev, "unrecognized message signature (%x != %x)\n",
647 nlh->magic, htonl(UDEV_MONITOR_MAGIC));
650 if (nlh->properties_off+32 > buflen)
652 bufpos = nlh->properties_off;
654 /* kernel message with header */
655 bufpos = strlen(buf) + 1;
656 if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
657 dbg(udev_monitor->udev, "invalid message length\n");
661 /* check message header */
662 if (strstr(buf, "@/") == NULL) {
663 dbg(udev_monitor->udev, "unrecognized message header\n");
668 udev_device = udev_device_new(udev_monitor->udev);
669 if (udev_device == NULL)
671 udev_device_set_info_loaded(udev_device);
673 while (bufpos < buflen) {
678 keylen = strlen(key);
681 bufpos += keylen + 1;
682 udev_device_add_property_from_string_parse(udev_device, key);
685 if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
686 dbg(udev_monitor->udev, "missing values, invalid device\n");
687 udev_device_unref(udev_device);
691 /* skip device, if it does not pass the current filter */
692 if (!passes_filter(udev_monitor, udev_device)) {
693 struct pollfd pfd[1];
696 udev_device_unref(udev_device);
698 /* if something is queued, get next device */
699 pfd[0].fd = udev_monitor->sock;
700 pfd[0].events = POLLIN;
701 rc = poll(pfd, 1, 0);
710 int udev_monitor_send_device(struct udev_monitor *udev_monitor,
711 struct udev_monitor *destination, struct udev_device *udev_device)
717 blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
721 if (udev_monitor->sun.sun_family != 0) {
728 /* header <action>@<devpath> */
729 action = udev_device_get_action(udev_device);
733 if (util_strpcpyl(&s, sizeof(header), action, "@", udev_device_get_devpath(udev_device), NULL) == 0)
735 iov[0].iov_base = header;
736 iov[0].iov_len = (s - header)+1;
738 /* add properties list */
739 iov[1].iov_base = (char *)buf;
740 iov[1].iov_len = blen;
742 memset(&smsg, 0x00, sizeof(struct msghdr));
745 smsg.msg_name = &udev_monitor->sun;
746 smsg.msg_namelen = udev_monitor->addrlen;
747 count = sendmsg(udev_monitor->sock, &smsg, 0);
748 dbg(udev_monitor->udev, "passed %zi bytes to socket monitor %p\n", count, udev_monitor);
752 if (udev_monitor->snl.nl_family != 0) {
756 struct udev_monitor_netlink_header nlh;
757 struct udev_list_entry *list_entry;
758 uint64_t tag_bloom_bits;
760 /* add versioned header */
761 memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header));
762 memcpy(nlh.prefix, "libudev", 8);
763 nlh.magic = htonl(UDEV_MONITOR_MAGIC);
764 nlh.header_size = sizeof(struct udev_monitor_netlink_header);
765 val = udev_device_get_subsystem(udev_device);
766 nlh.filter_subsystem_hash = htonl(util_string_hash32(val));
767 val = udev_device_get_devtype(udev_device);
769 nlh.filter_devtype_hash = htonl(util_string_hash32(val));
770 iov[0].iov_base = &nlh;
771 iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
773 /* add tag bloom filter */
775 udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
776 tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry));
777 if (tag_bloom_bits > 0) {
778 nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32);
779 nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff);
782 /* add properties list */
783 nlh.properties_off = iov[0].iov_len;
784 nlh.properties_len = blen;
785 iov[1].iov_base = (char *)buf;
786 iov[1].iov_len = blen;
788 memset(&smsg, 0x00, sizeof(struct msghdr));
792 * Use custom address for target, or the default one.
794 * If we send to a multicast group, we will get
795 * ECONNREFUSED, which is expected.
797 if (destination != NULL)
798 smsg.msg_name = &destination->snl;
800 smsg.msg_name = &udev_monitor->snl_destination;
801 smsg.msg_namelen = sizeof(struct sockaddr_nl);
802 count = sendmsg(udev_monitor->sock, &smsg, 0);
803 dbg(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor);
811 * udev_monitor_filter_add_match_subsystem_devtype:
812 * @udev_monitor: the monitor
813 * @subsystem: the subsystem value to match the incoming devices against
814 * @devtype: the devtype value to match the incoming devices against
816 * This filter is efficiently executed inside the kernel, and libudev subscribers
817 * will usually not be woken up for devices which do not match.
819 * The filter must be installed before the monitor is switched to listening mode.
821 * Returns: 0 on success, otherwise a negative error value.
823 _public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
825 if (udev_monitor == NULL)
827 if (subsystem == NULL)
829 if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL)
835 * udev_monitor_filter_add_match_tag:
836 * @udev_monitor: the monitor
837 * @tag: the name of a tag
839 * This filter is efficiently executed inside the kernel, and libudev subscribers
840 * will usually not be woken up for devices which do not match.
842 * The filter must be installed before the monitor is switched to listening mode.
844 * Returns: 0 on success, otherwise a negative error value.
846 _public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
848 if (udev_monitor == NULL)
852 if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL)
858 * udev_monitor_filter_remove:
859 * @udev_monitor: monitor
861 * Remove all filters from monitor.
863 * Returns: 0 on success, otherwise a negative error value.
865 _public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
867 static struct sock_fprog filter = { 0, NULL };
869 udev_list_cleanup(&udev_monitor->filter_subsystem_list);
870 return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));