diff options
Diffstat (limited to 'src/libudev/libudev-monitor.c')
| -rw-r--r-- | src/libudev/libudev-monitor.c | 782 |
1 files changed, 782 insertions, 0 deletions
diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c new file mode 100644 index 0000000000..4406b55f97 --- /dev/null +++ b/src/libudev/libudev-monitor.c @@ -0,0 +1,782 @@ +/* + * libudev - interface to udev device information + * + * Copyright (C) 2008-2010 Kay Sievers <kay.sievers@vrfy.org> + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <stddef.h> +#include <unistd.h> +#include <errno.h> +#include <string.h> +#include <dirent.h> +#include <sys/poll.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <sys/un.h> +#include <arpa/inet.h> +#include <linux/netlink.h> +#include <linux/filter.h> + +#include "libudev.h" +#include "libudev-private.h" +#include "socket-util.h" + +/** + * SECTION:libudev-monitor + * @short_description: device event source + * + * Connects to a device event source. + */ + +/** + * udev_monitor: + * + * Opaque object handling an event source. + */ +struct udev_monitor { + struct udev *udev; + int refcount; + int sock; + union sockaddr_union snl; + union sockaddr_union snl_trusted_sender; + union sockaddr_union snl_destination; + socklen_t addrlen; + struct udev_list filter_subsystem_list; + struct udev_list filter_tag_list; + bool bound; +}; + +enum udev_monitor_netlink_group { + UDEV_MONITOR_NONE, + UDEV_MONITOR_KERNEL, + UDEV_MONITOR_UDEV, +}; + +#define UDEV_MONITOR_MAGIC 0xfeedcafe +struct udev_monitor_netlink_header { + /* "libudev" prefix to distinguish libudev and kernel messages */ + char prefix[8]; + /* + * magic to protect against daemon <-> library message format mismatch + * used in the kernel from socket filter rules; needs to be stored in network order + */ + unsigned int magic; + /* total length of header structure known to the sender */ + unsigned int header_size; + /* properties string buffer */ + unsigned int properties_off; + unsigned int properties_len; + /* + * hashes of primary device properties strings, to let libudev subscribers + * use in-kernel socket filters; values need to be stored in network order + */ + unsigned int filter_subsystem_hash; + unsigned int filter_devtype_hash; + unsigned int filter_tag_bloom_hi; + unsigned int filter_tag_bloom_lo; +}; + +static struct udev_monitor *udev_monitor_new(struct udev *udev) +{ + struct udev_monitor *udev_monitor; + + udev_monitor = calloc(1, sizeof(struct udev_monitor)); + if (udev_monitor == NULL) + return NULL; + udev_monitor->refcount = 1; + udev_monitor->udev = udev; + udev_list_init(udev, &udev_monitor->filter_subsystem_list, false); + udev_list_init(udev, &udev_monitor->filter_tag_list, true); + return udev_monitor; +} + +/** + * udev_monitor_new_from_socket: + * @udev: udev library context + * @socket_path: unix socket path + * + * This function is removed from libudev and will not do anything. + * + * Returns: #NULL + **/ +_public_ struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path) +{ + errno = ENOSYS; + return NULL; +} + +struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd) +{ + struct udev_monitor *udev_monitor; + unsigned int group; + + if (udev == NULL) + return NULL; + + if (name == NULL) + group = UDEV_MONITOR_NONE; + else if (strcmp(name, "udev") == 0) + group = UDEV_MONITOR_UDEV; + else if (strcmp(name, "kernel") == 0) + group = UDEV_MONITOR_KERNEL; + else + return NULL; + + udev_monitor = udev_monitor_new(udev); + if (udev_monitor == NULL) + return NULL; + + if (fd < 0) { + udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT); + if (udev_monitor->sock == -1) { + err(udev, "error getting socket: %m\n"); + free(udev_monitor); + return NULL; + } + } else { + udev_monitor->bound = true; + udev_monitor->sock = fd; + } + + udev_monitor->snl.nl.nl_family = AF_NETLINK; + udev_monitor->snl.nl.nl_groups = group; + + /* default destination for sending */ + udev_monitor->snl_destination.nl.nl_family = AF_NETLINK; + udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV; + + return udev_monitor; +} + +/** + * udev_monitor_new_from_netlink: + * @udev: udev library context + * @name: name of event source + * + * Create new udev monitor and connect to a specified event + * source. Valid sources identifiers are "udev" and "kernel". + * + * Applications should usually not connect directly to the + * "kernel" events, because the devices might not be useable + * at that time, before udev has configured them, and created + * device nodes. Accessing devices at the same time as udev, + * might result in unpredictable behavior. The "udev" events + * are sent out after udev has finished its event processing, + * all rules have been processed, and needed device nodes are + * created. + * + * The initial refcount is 1, and needs to be decremented to + * release the resources of the udev monitor. + * + * Returns: a new udev monitor, or #NULL, in case of an error + **/ +_public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name) +{ + return udev_monitor_new_from_netlink_fd(udev, name, -1); +} + +static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i, + unsigned short code, unsigned int data) +{ + struct sock_filter *ins = &inss[*i]; + + ins->code = code; + ins->k = data; + (*i)++; +} + +static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i, + unsigned short code, unsigned int data, + unsigned short jt, unsigned short jf) +{ + struct sock_filter *ins = &inss[*i]; + + ins->code = code; + ins->jt = jt; + ins->jf = jf; + ins->k = data; + (*i)++; +} + +/** + * udev_monitor_filter_update: + * @udev_monitor: monitor + * + * Update the installed socket filter. This is only needed, + * if the filter was removed or changed. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor) +{ + struct sock_filter ins[512]; + struct sock_fprog filter; + unsigned int i; + struct udev_list_entry *list_entry; + int err; + + if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL && + udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL) + return 0; + + memset(ins, 0x00, sizeof(ins)); + i = 0; + + /* load magic in A */ + bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic)); + /* jump if magic matches */ + bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0); + /* wrong magic, pass packet */ + bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); + + if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) { + int tag_matches; + + /* count tag matches, to calculate end of tag match block */ + tag_matches = 0; + udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) + tag_matches++; + + /* add all tags matches */ + udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) { + uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry)); + uint32_t tag_bloom_hi = tag_bloom_bits >> 32; + uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff; + + /* load device bloom bits in A */ + bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi)); + /* clear bits (tag bits & bloom bits) */ + bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi); + /* jump to next tag if it does not match */ + bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3); + + /* load device bloom bits in A */ + bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo)); + /* clear bits (tag bits & bloom bits) */ + bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo); + /* jump behind end of tag match block if tag matches */ + tag_matches--; + bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0); + } + + /* nothing matched, drop packet */ + bpf_stmt(ins, &i, BPF_RET|BPF_K, 0); + } + + /* add all subsystem matches */ + if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) { + udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) { + unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry)); + + /* load device subsystem value in A */ + bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash)); + if (udev_list_entry_get_value(list_entry) == NULL) { + /* jump if subsystem does not match */ + bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1); + } else { + /* jump if subsystem does not match */ + bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3); + + /* load device devtype value in A */ + bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash)); + /* jump if value does not match */ + hash = util_string_hash32(udev_list_entry_get_value(list_entry)); + bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1); + } + + /* matched, pass packet */ + bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); + + if (i+1 >= ARRAY_SIZE(ins)) + return -1; + } + + /* nothing matched, drop packet */ + bpf_stmt(ins, &i, BPF_RET|BPF_K, 0); + } + + /* matched, pass packet */ + bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff); + + /* install filter */ + memset(&filter, 0x00, sizeof(filter)); + filter.len = i; + filter.filter = ins; + err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); + return err; +} + +int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender) +{ + udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid; + return 0; +} +/** + * udev_monitor_enable_receiving: + * @udev_monitor: the monitor which should receive events + * + * Binds the @udev_monitor socket to the event source. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor) +{ + int err = 0; + const int on = 1; + + if (udev_monitor->snl.nl.nl_family == 0) + return -EINVAL; + + udev_monitor_filter_update(udev_monitor); + + if (!udev_monitor->bound) { + err = bind(udev_monitor->sock, + &udev_monitor->snl.sa, sizeof(struct sockaddr_nl)); + if (err == 0) + udev_monitor->bound = true; + } + + if (err >= 0) { + union sockaddr_union snl; + socklen_t addrlen; + + /* + * get the address the kernel has assigned us + * it is usually, but not necessarily the pid + */ + addrlen = sizeof(struct sockaddr_nl); + err = getsockname(udev_monitor->sock, &snl.sa, &addrlen); + if (err == 0) + udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid; + } else { + err(udev_monitor->udev, "bind failed: %m\n"); + return err; + } + + /* enable receiving of sender credentials */ + setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)); + return 0; +} + +/** + * udev_monitor_set_receive_buffer_size: + * @udev_monitor: the monitor which should receive events + * @size: the size in bytes + * + * Set the size of the kernel socket buffer. This call needs the + * appropriate privileges to succeed. + * + * Returns: 0 on success, otherwise -1 on error. + */ +_public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size) +{ + if (udev_monitor == NULL) + return -1; + return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size)); +} + +int udev_monitor_disconnect(struct udev_monitor *udev_monitor) +{ + int err; + + err = close(udev_monitor->sock); + udev_monitor->sock = -1; + return err; +} + +/** + * udev_monitor_ref: + * @udev_monitor: udev monitor + * + * Take a reference of a udev monitor. + * + * Returns: the passed udev monitor + **/ +_public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor) +{ + if (udev_monitor == NULL) + return NULL; + udev_monitor->refcount++; + return udev_monitor; +} + +/** + * udev_monitor_unref: + * @udev_monitor: udev monitor + * + * Drop a reference of a udev monitor. If the refcount reaches zero, + * the bound socket will be closed, and the resources of the monitor + * will be released. + * + **/ +_public_ void udev_monitor_unref(struct udev_monitor *udev_monitor) +{ + if (udev_monitor == NULL) + return; + udev_monitor->refcount--; + if (udev_monitor->refcount > 0) + return; + if (udev_monitor->sock >= 0) + close(udev_monitor->sock); + udev_list_cleanup(&udev_monitor->filter_subsystem_list); + udev_list_cleanup(&udev_monitor->filter_tag_list); + free(udev_monitor); +} + +/** + * udev_monitor_get_udev: + * @udev_monitor: udev monitor + * + * Retrieve the udev library context the monitor was created with. + * + * Returns: the udev library context + **/ +_public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor) +{ + if (udev_monitor == NULL) + return NULL; + return udev_monitor->udev; +} + +/** + * udev_monitor_get_fd: + * @udev_monitor: udev monitor + * + * Retrieve the socket file descriptor associated with the monitor. + * + * Returns: the socket file descriptor + **/ +_public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor) +{ + if (udev_monitor == NULL) + return -1; + return udev_monitor->sock; +} + +static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device) +{ + struct udev_list_entry *list_entry; + + if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL) + goto tag; + udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) { + const char *subsys = udev_list_entry_get_name(list_entry); + const char *dsubsys = udev_device_get_subsystem(udev_device); + const char *devtype; + const char *ddevtype; + + if (strcmp(dsubsys, subsys) != 0) + continue; + + devtype = udev_list_entry_get_value(list_entry); + if (devtype == NULL) + goto tag; + ddevtype = udev_device_get_devtype(udev_device); + if (ddevtype == NULL) + continue; + if (strcmp(ddevtype, devtype) == 0) + goto tag; + } + return 0; + +tag: + if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL) + return 1; + udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) { + const char *tag = udev_list_entry_get_name(list_entry); + + if (udev_device_has_tag(udev_device, tag)) + return 1; + } + return 0; +} + +/** + * udev_monitor_receive_device: + * @udev_monitor: udev monitor + * + * Receive data from the udev monitor socket, allocate a new udev + * device, fill in the received data, and return the device. + * + * Only socket connections with uid=0 are accepted. + * + * The initial refcount is 1, and needs to be decremented to + * release the resources of the udev device. + * + * Returns: a new udev device, or #NULL, in case of an error + **/ +_public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor) +{ + struct udev_device *udev_device; + struct msghdr smsg; + struct iovec iov; + char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; + struct cmsghdr *cmsg; + union sockaddr_union snl; + struct ucred *cred; + char buf[8192]; + ssize_t buflen; + ssize_t bufpos; + struct udev_monitor_netlink_header *nlh; + +retry: + if (udev_monitor == NULL) + return NULL; + 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); + + if (udev_monitor->snl.nl.nl_family != 0) { + smsg.msg_name = &snl; + smsg.msg_namelen = sizeof(snl); + } + + buflen = recvmsg(udev_monitor->sock, &smsg, 0); + if (buflen < 0) { + if (errno != EINTR) + dbg(udev_monitor->udev, "unable to receive message\n"); + return NULL; + } + + if (buflen < 32 || (size_t)buflen >= sizeof(buf)) { + dbg(udev_monitor->udev, "invalid message length\n"); + return NULL; + } + + if (udev_monitor->snl.nl.nl_family != 0) { + if (snl.nl.nl_groups == 0) { + /* unicast message, check if we trust the sender */ + if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 || + snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) { + dbg(udev_monitor->udev, "unicast netlink message ignored\n"); + return NULL; + } + } else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) { + if (snl.nl.nl_pid > 0) { + dbg(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n", + snl.nl.nl_pid); + return NULL; + } + } + } + + cmsg = CMSG_FIRSTHDR(&smsg); + if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) { + dbg(udev_monitor->udev, "no sender credentials received, message ignored\n"); + return NULL; + } + + cred = (struct ucred *)CMSG_DATA(cmsg); + if (cred->uid != 0) { + dbg(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid); + return NULL; + } + + if (memcmp(buf, "libudev", 8) == 0) { + /* udev message needs proper version magic */ + nlh = (struct udev_monitor_netlink_header *) buf; + if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) { + err(udev_monitor->udev, "unrecognized message signature (%x != %x)\n", + nlh->magic, htonl(UDEV_MONITOR_MAGIC)); + return NULL; + } + if (nlh->properties_off+32 > buflen) + return NULL; + bufpos = nlh->properties_off; + } else { + /* kernel message with header */ + bufpos = strlen(buf) + 1; + if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) { + dbg(udev_monitor->udev, "invalid message length\n"); + return NULL; + } + + /* check message header */ + if (strstr(buf, "@/") == NULL) { + dbg(udev_monitor->udev, "unrecognized message header\n"); + return NULL; + } + } + + udev_device = udev_device_new(udev_monitor->udev); + if (udev_device == NULL) + return NULL; + udev_device_set_info_loaded(udev_device); + + while (bufpos < buflen) { + char *key; + size_t keylen; + + key = &buf[bufpos]; + keylen = strlen(key); + if (keylen == 0) + break; + bufpos += keylen + 1; + udev_device_add_property_from_string_parse(udev_device, key); + } + + if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) { + dbg(udev_monitor->udev, "missing values, invalid device\n"); + udev_device_unref(udev_device); + return NULL; + } + + /* skip device, if it does not pass the current filter */ + if (!passes_filter(udev_monitor, udev_device)) { + struct pollfd pfd[1]; + int rc; + + udev_device_unref(udev_device); + + /* if something is queued, get next device */ + pfd[0].fd = udev_monitor->sock; + pfd[0].events = POLLIN; + rc = poll(pfd, 1, 0); + if (rc > 0) + goto retry; + return NULL; + } + + return udev_device; +} + +int udev_monitor_send_device(struct udev_monitor *udev_monitor, + struct udev_monitor *destination, struct udev_device *udev_device) +{ + const char *buf; + ssize_t blen; + ssize_t count; + struct msghdr smsg; + struct iovec iov[2]; + const char *val; + struct udev_monitor_netlink_header nlh; + struct udev_list_entry *list_entry; + uint64_t tag_bloom_bits; + + if (udev_monitor->snl.nl.nl_family == 0) + return -EINVAL; + + blen = udev_device_get_properties_monitor_buf(udev_device, &buf); + if (blen < 32) + return -EINVAL; + + /* add versioned header */ + memset(&nlh, 0x00, sizeof(struct udev_monitor_netlink_header)); + memcpy(nlh.prefix, "libudev", 8); + nlh.magic = htonl(UDEV_MONITOR_MAGIC); + nlh.header_size = sizeof(struct udev_monitor_netlink_header); + val = udev_device_get_subsystem(udev_device); + nlh.filter_subsystem_hash = htonl(util_string_hash32(val)); + val = udev_device_get_devtype(udev_device); + if (val != NULL) + nlh.filter_devtype_hash = htonl(util_string_hash32(val)); + iov[0].iov_base = &nlh; + iov[0].iov_len = sizeof(struct udev_monitor_netlink_header); + + /* add tag bloom filter */ + tag_bloom_bits = 0; + udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device)) + tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry)); + if (tag_bloom_bits > 0) { + nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32); + nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff); + } + + /* add properties list */ + nlh.properties_off = iov[0].iov_len; + nlh.properties_len = blen; + iov[1].iov_base = (char *)buf; + iov[1].iov_len = blen; + + memset(&smsg, 0x00, sizeof(struct msghdr)); + smsg.msg_iov = iov; + smsg.msg_iovlen = 2; + /* + * Use custom address for target, or the default one. + * + * If we send to a multicast group, we will get + * ECONNREFUSED, which is expected. + */ + if (destination != NULL) + smsg.msg_name = &destination->snl; + else + smsg.msg_name = &udev_monitor->snl_destination; + smsg.msg_namelen = sizeof(struct sockaddr_nl); + count = sendmsg(udev_monitor->sock, &smsg, 0); + dbg(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor); + return count; +} + +/** + * udev_monitor_filter_add_match_subsystem_devtype: + * @udev_monitor: the monitor + * @subsystem: the subsystem value to match the incoming devices against + * @devtype: the devtype value to match the incoming devices against + * + * This filter is efficiently executed inside the kernel, and libudev subscribers + * will usually not be woken up for devices which do not match. + * + * The filter must be installed before the monitor is switched to listening mode. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype) +{ + if (udev_monitor == NULL) + return -EINVAL; + if (subsystem == NULL) + return -EINVAL; + if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL) + return -ENOMEM; + return 0; +} + +/** + * udev_monitor_filter_add_match_tag: + * @udev_monitor: the monitor + * @tag: the name of a tag + * + * This filter is efficiently executed inside the kernel, and libudev subscribers + * will usually not be woken up for devices which do not match. + * + * The filter must be installed before the monitor is switched to listening mode. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag) +{ + if (udev_monitor == NULL) + return -EINVAL; + if (tag == NULL) + return -EINVAL; + if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL) + return -ENOMEM; + return 0; +} + +/** + * udev_monitor_filter_remove: + * @udev_monitor: monitor + * + * Remove all filters from monitor. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor) +{ + static struct sock_fprog filter = { 0, NULL }; + + udev_list_cleanup(&udev_monitor->filter_subsystem_list); + return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); +} |