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/>.
21 #include <linux/filter.h>
22 #include <linux/netlink.h>
28 #include <sys/socket.h>
33 #include "alloc-util.h"
36 #include "formats-util.h"
37 #include "libudev-private.h"
39 #include "mount-util.h"
40 #include "socket-util.h"
41 #include "string-util.h"
44 * SECTION:libudev-monitor
45 * @short_description: device event source
47 * Connects to a device event source.
53 * Opaque object handling an event source.
59 union sockaddr_union snl
;
60 union sockaddr_union snl_trusted_sender
;
61 union sockaddr_union snl_destination
;
63 struct udev_list filter_subsystem_list
;
64 struct udev_list filter_tag_list
;
68 enum udev_monitor_netlink_group
{
74 #define UDEV_MONITOR_MAGIC 0xfeedcafe
75 struct udev_monitor_netlink_header
{
76 /* "libudev" prefix to distinguish libudev and kernel messages */
79 * magic to protect against daemon <-> library message format mismatch
80 * used in the kernel from socket filter rules; needs to be stored in network order
83 /* total length of header structure known to the sender */
84 unsigned int header_size
;
85 /* properties string buffer */
86 unsigned int properties_off
;
87 unsigned int properties_len
;
89 * hashes of primary device properties strings, to let libudev subscribers
90 * use in-kernel socket filters; values need to be stored in network order
92 unsigned int filter_subsystem_hash
;
93 unsigned int filter_devtype_hash
;
94 unsigned int filter_tag_bloom_hi
;
95 unsigned int filter_tag_bloom_lo
;
98 static struct udev_monitor
*udev_monitor_new(struct udev
*udev
)
100 struct udev_monitor
*udev_monitor
;
102 udev_monitor
= new0(struct udev_monitor
, 1);
103 if (udev_monitor
== NULL
)
105 udev_monitor
->refcount
= 1;
106 udev_monitor
->udev
= udev
;
107 udev_list_init(udev
, &udev_monitor
->filter_subsystem_list
, false);
108 udev_list_init(udev
, &udev_monitor
->filter_tag_list
, true);
112 /* we consider udev running when /dev is on devtmpfs */
113 static bool udev_has_devtmpfs(struct udev
*udev
) {
115 union file_handle_union h
= FILE_HANDLE_INIT
;
116 _cleanup_fclose_
FILE *f
= NULL
;
117 char line
[LINE_MAX
], *e
;
121 r
= name_to_handle_at(AT_FDCWD
, "/dev", &h
.handle
, &mount_id
, 0);
123 if (errno
!= EOPNOTSUPP
)
124 log_debug_errno(errno
, "name_to_handle_at on /dev: %m");
128 f
= fopen("/proc/self/mountinfo", "re");
132 FOREACH_LINE(line
, f
, return false) {
135 if (sscanf(line
, "%i", &mid
) != 1)
141 e
= strstr(line
, " - ");
145 /* accept any name that starts with the currently expected type */
146 if (startswith(e
+ 3, "devtmpfs"))
153 static void monitor_set_nl_address(struct udev_monitor
*udev_monitor
) {
154 union sockaddr_union snl
;
158 assert(udev_monitor
);
160 /* get the address the kernel has assigned us
161 * it is usually, but not necessarily the pid
163 addrlen
= sizeof(struct sockaddr_nl
);
164 r
= getsockname(udev_monitor
->sock
, &snl
.sa
, &addrlen
);
166 udev_monitor
->snl
.nl
.nl_pid
= snl
.nl
.nl_pid
;
169 struct udev_monitor
*udev_monitor_new_from_netlink_fd(struct udev
*udev
, const char *name
, int fd
)
171 struct udev_monitor
*udev_monitor
;
178 group
= UDEV_MONITOR_NONE
;
179 else if (streq(name
, "udev")) {
181 * We do not support subscribing to uevents if no instance of
182 * udev is running. Uevents would otherwise broadcast the
183 * processing data of the host into containers, which is not
186 * Containers will currently not get any udev uevents, until
187 * a supporting infrastructure is available.
189 * We do not set a netlink multicast group here, so the socket
190 * will not receive any messages.
192 if (access("/run/udev/control", F_OK
) < 0 && !udev_has_devtmpfs(udev
)) {
193 log_debug("the udev service seems not to be active, disable the monitor");
194 group
= UDEV_MONITOR_NONE
;
196 group
= UDEV_MONITOR_UDEV
;
197 } else if (streq(name
, "kernel"))
198 group
= UDEV_MONITOR_KERNEL
;
202 udev_monitor
= udev_monitor_new(udev
);
203 if (udev_monitor
== NULL
)
207 udev_monitor
->sock
= socket(PF_NETLINK
, SOCK_RAW
|SOCK_CLOEXEC
|SOCK_NONBLOCK
, NETLINK_KOBJECT_UEVENT
);
208 if (udev_monitor
->sock
< 0) {
209 log_debug_errno(errno
, "error getting socket: %m");
214 udev_monitor
->bound
= true;
215 udev_monitor
->sock
= fd
;
216 monitor_set_nl_address(udev_monitor
);
219 udev_monitor
->snl
.nl
.nl_family
= AF_NETLINK
;
220 udev_monitor
->snl
.nl
.nl_groups
= group
;
222 /* default destination for sending */
223 udev_monitor
->snl_destination
.nl
.nl_family
= AF_NETLINK
;
224 udev_monitor
->snl_destination
.nl
.nl_groups
= UDEV_MONITOR_UDEV
;
230 * udev_monitor_new_from_netlink:
231 * @udev: udev library context
232 * @name: name of event source
234 * Create new udev monitor and connect to a specified event
235 * source. Valid sources identifiers are "udev" and "kernel".
237 * Applications should usually not connect directly to the
238 * "kernel" events, because the devices might not be useable
239 * at that time, before udev has configured them, and created
240 * device nodes. Accessing devices at the same time as udev,
241 * might result in unpredictable behavior. The "udev" events
242 * are sent out after udev has finished its event processing,
243 * all rules have been processed, and needed device nodes are
246 * The initial refcount is 1, and needs to be decremented to
247 * release the resources of the udev monitor.
249 * Returns: a new udev monitor, or #NULL, in case of an error
251 _public_
struct udev_monitor
*udev_monitor_new_from_netlink(struct udev
*udev
, const char *name
)
253 return udev_monitor_new_from_netlink_fd(udev
, name
, -1);
256 static inline void bpf_stmt(struct sock_filter
*inss
, unsigned int *i
,
257 unsigned short code
, unsigned int data
)
259 struct sock_filter
*ins
= &inss
[*i
];
266 static inline void bpf_jmp(struct sock_filter
*inss
, unsigned int *i
,
267 unsigned short code
, unsigned int data
,
268 unsigned short jt
, unsigned short jf
)
270 struct sock_filter
*ins
= &inss
[*i
];
280 * udev_monitor_filter_update:
281 * @udev_monitor: monitor
283 * Update the installed socket filter. This is only needed,
284 * if the filter was removed or changed.
286 * Returns: 0 on success, otherwise a negative error value.
288 _public_
int udev_monitor_filter_update(struct udev_monitor
*udev_monitor
)
290 struct sock_filter ins
[512];
291 struct sock_fprog filter
;
293 struct udev_list_entry
*list_entry
;
296 if (udev_list_get_entry(&udev_monitor
->filter_subsystem_list
) == NULL
&&
297 udev_list_get_entry(&udev_monitor
->filter_tag_list
) == NULL
)
300 memzero(ins
, sizeof(ins
));
303 /* load magic in A */
304 bpf_stmt(ins
, &i
, BPF_LD
|BPF_W
|BPF_ABS
, offsetof(struct udev_monitor_netlink_header
, magic
));
305 /* jump if magic matches */
306 bpf_jmp(ins
, &i
, BPF_JMP
|BPF_JEQ
|BPF_K
, UDEV_MONITOR_MAGIC
, 1, 0);
307 /* wrong magic, pass packet */
308 bpf_stmt(ins
, &i
, BPF_RET
|BPF_K
, 0xffffffff);
310 if (udev_list_get_entry(&udev_monitor
->filter_tag_list
) != NULL
) {
313 /* count tag matches, to calculate end of tag match block */
315 udev_list_entry_foreach(list_entry
, udev_list_get_entry(&udev_monitor
->filter_tag_list
))
318 /* add all tags matches */
319 udev_list_entry_foreach(list_entry
, udev_list_get_entry(&udev_monitor
->filter_tag_list
)) {
320 uint64_t tag_bloom_bits
= util_string_bloom64(udev_list_entry_get_name(list_entry
));
321 uint32_t tag_bloom_hi
= tag_bloom_bits
>> 32;
322 uint32_t tag_bloom_lo
= tag_bloom_bits
& 0xffffffff;
324 /* load device bloom bits in A */
325 bpf_stmt(ins
, &i
, BPF_LD
|BPF_W
|BPF_ABS
, offsetof(struct udev_monitor_netlink_header
, filter_tag_bloom_hi
));
326 /* clear bits (tag bits & bloom bits) */
327 bpf_stmt(ins
, &i
, BPF_ALU
|BPF_AND
|BPF_K
, tag_bloom_hi
);
328 /* jump to next tag if it does not match */
329 bpf_jmp(ins
, &i
, BPF_JMP
|BPF_JEQ
|BPF_K
, tag_bloom_hi
, 0, 3);
331 /* load device bloom bits in A */
332 bpf_stmt(ins
, &i
, BPF_LD
|BPF_W
|BPF_ABS
, offsetof(struct udev_monitor_netlink_header
, filter_tag_bloom_lo
));
333 /* clear bits (tag bits & bloom bits) */
334 bpf_stmt(ins
, &i
, BPF_ALU
|BPF_AND
|BPF_K
, tag_bloom_lo
);
335 /* jump behind end of tag match block if tag matches */
337 bpf_jmp(ins
, &i
, BPF_JMP
|BPF_JEQ
|BPF_K
, tag_bloom_lo
, 1 + (tag_matches
* 6), 0);
340 /* nothing matched, drop packet */
341 bpf_stmt(ins
, &i
, BPF_RET
|BPF_K
, 0);
344 /* add all subsystem matches */
345 if (udev_list_get_entry(&udev_monitor
->filter_subsystem_list
) != NULL
) {
346 udev_list_entry_foreach(list_entry
, udev_list_get_entry(&udev_monitor
->filter_subsystem_list
)) {
347 unsigned int hash
= util_string_hash32(udev_list_entry_get_name(list_entry
));
349 /* load device subsystem value in A */
350 bpf_stmt(ins
, &i
, BPF_LD
|BPF_W
|BPF_ABS
, offsetof(struct udev_monitor_netlink_header
, filter_subsystem_hash
));
351 if (udev_list_entry_get_value(list_entry
) == NULL
) {
352 /* jump if subsystem does not match */
353 bpf_jmp(ins
, &i
, BPF_JMP
|BPF_JEQ
|BPF_K
, hash
, 0, 1);
355 /* jump if subsystem does not match */
356 bpf_jmp(ins
, &i
, BPF_JMP
|BPF_JEQ
|BPF_K
, hash
, 0, 3);
358 /* load device devtype value in A */
359 bpf_stmt(ins
, &i
, BPF_LD
|BPF_W
|BPF_ABS
, offsetof(struct udev_monitor_netlink_header
, filter_devtype_hash
));
360 /* jump if value does not match */
361 hash
= util_string_hash32(udev_list_entry_get_value(list_entry
));
362 bpf_jmp(ins
, &i
, BPF_JMP
|BPF_JEQ
|BPF_K
, hash
, 0, 1);
365 /* matched, pass packet */
366 bpf_stmt(ins
, &i
, BPF_RET
|BPF_K
, 0xffffffff);
368 if (i
+1 >= ELEMENTSOF(ins
))
372 /* nothing matched, drop packet */
373 bpf_stmt(ins
, &i
, BPF_RET
|BPF_K
, 0);
376 /* matched, pass packet */
377 bpf_stmt(ins
, &i
, BPF_RET
|BPF_K
, 0xffffffff);
380 memzero(&filter
, sizeof(filter
));
383 err
= setsockopt(udev_monitor
->sock
, SOL_SOCKET
, SO_ATTACH_FILTER
, &filter
, sizeof(filter
));
384 return err
< 0 ? -errno
: 0;
387 int udev_monitor_allow_unicast_sender(struct udev_monitor
*udev_monitor
, struct udev_monitor
*sender
)
389 udev_monitor
->snl_trusted_sender
.nl
.nl_pid
= sender
->snl
.nl
.nl_pid
;
394 * udev_monitor_enable_receiving:
395 * @udev_monitor: the monitor which should receive events
397 * Binds the @udev_monitor socket to the event source.
399 * Returns: 0 on success, otherwise a negative error value.
401 _public_
int udev_monitor_enable_receiving(struct udev_monitor
*udev_monitor
)
406 udev_monitor_filter_update(udev_monitor
);
408 if (!udev_monitor
->bound
) {
409 err
= bind(udev_monitor
->sock
,
410 &udev_monitor
->snl
.sa
, sizeof(struct sockaddr_nl
));
412 udev_monitor
->bound
= true;
416 monitor_set_nl_address(udev_monitor
);
418 return log_debug_errno(errno
, "bind failed: %m");
420 /* enable receiving of sender credentials */
421 err
= setsockopt(udev_monitor
->sock
, SOL_SOCKET
, SO_PASSCRED
, &on
, sizeof(on
));
423 log_debug_errno(errno
, "setting SO_PASSCRED failed: %m");
429 * udev_monitor_set_receive_buffer_size:
430 * @udev_monitor: the monitor which should receive events
431 * @size: the size in bytes
433 * Set the size of the kernel socket buffer. This call needs the
434 * appropriate privileges to succeed.
436 * Returns: 0 on success, otherwise -1 on error.
438 _public_
int udev_monitor_set_receive_buffer_size(struct udev_monitor
*udev_monitor
, int size
)
440 if (udev_monitor
== NULL
)
442 return setsockopt(udev_monitor
->sock
, SOL_SOCKET
, SO_RCVBUFFORCE
, &size
, sizeof(size
));
445 int udev_monitor_disconnect(struct udev_monitor
*udev_monitor
)
449 err
= close(udev_monitor
->sock
);
450 udev_monitor
->sock
= -1;
451 return err
< 0 ? -errno
: 0;
456 * @udev_monitor: udev monitor
458 * Take a reference of a udev monitor.
460 * Returns: the passed udev monitor
462 _public_
struct udev_monitor
*udev_monitor_ref(struct udev_monitor
*udev_monitor
)
464 if (udev_monitor
== NULL
)
466 udev_monitor
->refcount
++;
471 * udev_monitor_unref:
472 * @udev_monitor: udev monitor
474 * Drop a reference of a udev monitor. If the refcount reaches zero,
475 * the bound socket will be closed, and the resources of the monitor
480 _public_
struct udev_monitor
*udev_monitor_unref(struct udev_monitor
*udev_monitor
)
482 if (udev_monitor
== NULL
)
484 udev_monitor
->refcount
--;
485 if (udev_monitor
->refcount
> 0)
487 if (udev_monitor
->sock
>= 0)
488 close(udev_monitor
->sock
);
489 udev_list_cleanup(&udev_monitor
->filter_subsystem_list
);
490 udev_list_cleanup(&udev_monitor
->filter_tag_list
);
496 * udev_monitor_get_udev:
497 * @udev_monitor: udev monitor
499 * Retrieve the udev library context the monitor was created with.
501 * Returns: the udev library context
503 _public_
struct udev
*udev_monitor_get_udev(struct udev_monitor
*udev_monitor
)
505 if (udev_monitor
== NULL
)
507 return udev_monitor
->udev
;
511 * udev_monitor_get_fd:
512 * @udev_monitor: udev monitor
514 * Retrieve the socket file descriptor associated with the monitor.
516 * Returns: the socket file descriptor
518 _public_
int udev_monitor_get_fd(struct udev_monitor
*udev_monitor
)
520 if (udev_monitor
== NULL
)
522 return udev_monitor
->sock
;
525 static int passes_filter(struct udev_monitor
*udev_monitor
, struct udev_device
*udev_device
)
527 struct udev_list_entry
*list_entry
;
529 if (udev_list_get_entry(&udev_monitor
->filter_subsystem_list
) == NULL
)
531 udev_list_entry_foreach(list_entry
, udev_list_get_entry(&udev_monitor
->filter_subsystem_list
)) {
532 const char *subsys
= udev_list_entry_get_name(list_entry
);
533 const char *dsubsys
= udev_device_get_subsystem(udev_device
);
535 const char *ddevtype
;
537 if (!streq(dsubsys
, subsys
))
540 devtype
= udev_list_entry_get_value(list_entry
);
543 ddevtype
= udev_device_get_devtype(udev_device
);
544 if (ddevtype
== NULL
)
546 if (streq(ddevtype
, devtype
))
552 if (udev_list_get_entry(&udev_monitor
->filter_tag_list
) == NULL
)
554 udev_list_entry_foreach(list_entry
, udev_list_get_entry(&udev_monitor
->filter_tag_list
)) {
555 const char *tag
= udev_list_entry_get_name(list_entry
);
557 if (udev_device_has_tag(udev_device
, tag
))
564 * udev_monitor_receive_device:
565 * @udev_monitor: udev monitor
567 * Receive data from the udev monitor socket, allocate a new udev
568 * device, fill in the received data, and return the device.
570 * Only socket connections with uid=0 are accepted.
572 * The monitor socket is by default set to NONBLOCK. A variant of poll() on
573 * the file descriptor returned by udev_monitor_get_fd() should to be used to
574 * wake up when new devices arrive, or alternatively the file descriptor
575 * switched into blocking mode.
577 * The initial refcount is 1, and needs to be decremented to
578 * release the resources of the udev device.
580 * Returns: a new udev device, or #NULL, in case of an error
582 _public_
struct udev_device
*udev_monitor_receive_device(struct udev_monitor
*udev_monitor
)
584 struct udev_device
*udev_device
;
587 char cred_msg
[CMSG_SPACE(sizeof(struct ucred
))];
588 struct cmsghdr
*cmsg
;
589 union sockaddr_union snl
;
592 struct udev_monitor_netlink_header nlh
;
597 bool is_initialized
= false;
600 if (udev_monitor
== NULL
)
603 iov
.iov_len
= sizeof(buf
);
604 memzero(&smsg
, sizeof(struct msghdr
));
607 smsg
.msg_control
= cred_msg
;
608 smsg
.msg_controllen
= sizeof(cred_msg
);
609 smsg
.msg_name
= &snl
;
610 smsg
.msg_namelen
= sizeof(snl
);
612 buflen
= recvmsg(udev_monitor
->sock
, &smsg
, 0);
615 log_debug("unable to receive message");
619 if (buflen
< 32 || (smsg
.msg_flags
& MSG_TRUNC
)) {
620 log_debug("invalid message length");
624 if (snl
.nl
.nl_groups
== 0) {
625 /* unicast message, check if we trust the sender */
626 if (udev_monitor
->snl_trusted_sender
.nl
.nl_pid
== 0 ||
627 snl
.nl
.nl_pid
!= udev_monitor
->snl_trusted_sender
.nl
.nl_pid
) {
628 log_debug("unicast netlink message ignored");
631 } else if (snl
.nl
.nl_groups
== UDEV_MONITOR_KERNEL
) {
632 if (snl
.nl
.nl_pid
> 0) {
633 log_debug("multicast kernel netlink message from PID %"PRIu32
" ignored",
639 cmsg
= CMSG_FIRSTHDR(&smsg
);
640 if (cmsg
== NULL
|| cmsg
->cmsg_type
!= SCM_CREDENTIALS
) {
641 log_debug("no sender credentials received, message ignored");
645 cred
= (struct ucred
*)CMSG_DATA(cmsg
);
646 if (cred
->uid
!= 0) {
647 log_debug("sender uid="UID_FMT
", message ignored", cred
->uid
);
651 if (memcmp(buf
.raw
, "libudev", 8) == 0) {
652 /* udev message needs proper version magic */
653 if (buf
.nlh
.magic
!= htobe32(UDEV_MONITOR_MAGIC
)) {
654 log_debug("unrecognized message signature (%x != %x)",
655 buf
.nlh
.magic
, htobe32(UDEV_MONITOR_MAGIC
));
658 if (buf
.nlh
.properties_off
+32 > (size_t)buflen
) {
659 log_debug("message smaller than expected (%u > %zd)",
660 buf
.nlh
.properties_off
+32, buflen
);
664 bufpos
= buf
.nlh
.properties_off
;
666 /* devices received from udev are always initialized */
667 is_initialized
= true;
669 /* kernel message with header */
670 bufpos
= strlen(buf
.raw
) + 1;
671 if ((size_t)bufpos
< sizeof("a@/d") || bufpos
>= buflen
) {
672 log_debug("invalid message length");
676 /* check message header */
677 if (strstr(buf
.raw
, "@/") == NULL
) {
678 log_debug("unrecognized message header");
683 udev_device
= udev_device_new_from_nulstr(udev_monitor
->udev
, &buf
.raw
[bufpos
], buflen
- bufpos
);
685 log_debug("could not create device: %m");
690 udev_device_set_is_initialized(udev_device
);
692 /* skip device, if it does not pass the current filter */
693 if (!passes_filter(udev_monitor
, udev_device
)) {
694 struct pollfd pfd
[1];
697 udev_device_unref(udev_device
);
699 /* if something is queued, get next device */
700 pfd
[0].fd
= udev_monitor
->sock
;
701 pfd
[0].events
= POLLIN
;
702 rc
= poll(pfd
, 1, 0);
711 int udev_monitor_send_device(struct udev_monitor
*udev_monitor
,
712 struct udev_monitor
*destination
, struct udev_device
*udev_device
)
714 const char *buf
, *val
;
716 struct udev_monitor_netlink_header nlh
= {
718 .magic
= htobe32(UDEV_MONITOR_MAGIC
),
719 .header_size
= sizeof nlh
,
721 struct iovec iov
[2] = {
722 { .iov_base
= &nlh
, .iov_len
= sizeof nlh
},
724 struct msghdr smsg
= {
728 struct udev_list_entry
*list_entry
;
729 uint64_t tag_bloom_bits
;
731 blen
= udev_device_get_properties_monitor_buf(udev_device
, &buf
);
733 log_debug("device buffer is too small to contain a valid device");
737 /* fill in versioned header */
738 val
= udev_device_get_subsystem(udev_device
);
739 nlh
.filter_subsystem_hash
= htobe32(util_string_hash32(val
));
741 val
= udev_device_get_devtype(udev_device
);
743 nlh
.filter_devtype_hash
= htobe32(util_string_hash32(val
));
745 /* add tag bloom filter */
747 udev_list_entry_foreach(list_entry
, udev_device_get_tags_list_entry(udev_device
))
748 tag_bloom_bits
|= util_string_bloom64(udev_list_entry_get_name(list_entry
));
749 if (tag_bloom_bits
> 0) {
750 nlh
.filter_tag_bloom_hi
= htobe32(tag_bloom_bits
>> 32);
751 nlh
.filter_tag_bloom_lo
= htobe32(tag_bloom_bits
& 0xffffffff);
754 /* add properties list */
755 nlh
.properties_off
= iov
[0].iov_len
;
756 nlh
.properties_len
= blen
;
757 iov
[1].iov_base
= (char *)buf
;
758 iov
[1].iov_len
= blen
;
761 * Use custom address for target, or the default one.
763 * If we send to a multicast group, we will get
764 * ECONNREFUSED, which is expected.
767 smsg
.msg_name
= &destination
->snl
;
769 smsg
.msg_name
= &udev_monitor
->snl_destination
;
770 smsg
.msg_namelen
= sizeof(struct sockaddr_nl
);
771 count
= sendmsg(udev_monitor
->sock
, &smsg
, 0);
773 if (!destination
&& errno
== ECONNREFUSED
) {
774 log_debug("passed device to netlink monitor %p", udev_monitor
);
780 log_debug("passed %zi byte device to netlink monitor %p", count
, udev_monitor
);
785 * udev_monitor_filter_add_match_subsystem_devtype:
786 * @udev_monitor: the monitor
787 * @subsystem: the subsystem value to match the incoming devices against
788 * @devtype: the devtype value to match the incoming devices against
790 * This filter is efficiently executed inside the kernel, and libudev subscribers
791 * will usually not be woken up for devices which do not match.
793 * The filter must be installed before the monitor is switched to listening mode.
795 * Returns: 0 on success, otherwise a negative error value.
797 _public_
int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor
*udev_monitor
, const char *subsystem
, const char *devtype
)
799 if (udev_monitor
== NULL
)
801 if (subsystem
== NULL
)
803 if (udev_list_entry_add(&udev_monitor
->filter_subsystem_list
, subsystem
, devtype
) == NULL
)
809 * udev_monitor_filter_add_match_tag:
810 * @udev_monitor: the monitor
811 * @tag: the name of a tag
813 * This filter is efficiently executed inside the kernel, and libudev subscribers
814 * will usually not be woken up for devices which do not match.
816 * The filter must be installed before the monitor is switched to listening mode.
818 * Returns: 0 on success, otherwise a negative error value.
820 _public_
int udev_monitor_filter_add_match_tag(struct udev_monitor
*udev_monitor
, const char *tag
)
822 if (udev_monitor
== NULL
)
826 if (udev_list_entry_add(&udev_monitor
->filter_tag_list
, tag
, NULL
) == NULL
)
832 * udev_monitor_filter_remove:
833 * @udev_monitor: monitor
835 * Remove all filters from monitor.
837 * Returns: 0 on success, otherwise a negative error value.
839 _public_
int udev_monitor_filter_remove(struct udev_monitor
*udev_monitor
)
841 static struct sock_fprog filter
= { 0, NULL
};
843 udev_list_cleanup(&udev_monitor
->filter_subsystem_list
);
844 return setsockopt(udev_monitor
->sock
, SOL_SOCKET
, SO_ATTACH_FILTER
, &filter
, sizeof(filter
));