/*
* uevent.c - trigger upon netlink uevents from the kernel
*
* Only kernels from version 2.6.10* on provide the uevent netlink socket.
* Until the libc-kernel-headers are updated, you need to compile with:
*
* gcc -I /lib/modules/`uname -r`/build/include -o uevent_listen uevent_listen.c
*
* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation version 2 of the License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <unistd.h>
#include <stdio.h>
#include <stdbool.h>
#include <errno.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <sys/socket.h>
#include <sys/user.h>
#include <sys/un.h>
#include <poll.h>
#include <linux/types.h>
#include <linux/netlink.h>
#include <pthread.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <libudev.h>
#include <errno.h>
#include "memory.h"
#include "debug.h"
#include "list.h"
#include "uevent.h"
#include "vector.h"
#include "structs.h"
#include "util.h"
#include "config.h"
#include "blacklist.h"
#include "devmapper.h"
#define MAX_ACCUMULATION_COUNT 2048
#define MAX_ACCUMULATION_TIME 30*1000
#define MIN_BURST_SPEED 10
typedef int (uev_trigger)(struct uevent *, void * trigger_data);
LIST_HEAD(uevq);
pthread_mutex_t uevq_lock = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t *uevq_lockp = &uevq_lock;
pthread_cond_t uev_cond = PTHREAD_COND_INITIALIZER;
pthread_cond_t *uev_condp = &uev_cond;
uev_trigger *my_uev_trigger;
void * my_trigger_data;
int servicing_uev;
int is_uevent_busy(void)
{
int empty;
pthread_mutex_lock(uevq_lockp);
empty = list_empty(&uevq);
pthread_mutex_unlock(uevq_lockp);
return (!empty || servicing_uev);
}
struct uevent * alloc_uevent (void)
{
struct uevent *uev = MALLOC(sizeof(struct uevent));
if (uev) {
INIT_LIST_HEAD(&uev->node);
INIT_LIST_HEAD(&uev->merge_node);
}
return uev;
}
void
uevq_cleanup(struct list_head *tmpq)
{
struct uevent *uev, *tmp;
list_for_each_entry_safe(uev, tmp, tmpq, node) {
list_del_init(&uev->node);
if (uev->udev)
udev_device_unref(uev->udev);
FREE(uev);
}
}
static const char* uevent_get_env_var(const struct uevent *uev,
const char *attr)
{
int i;
size_t len;
const char *p = NULL;
if (attr == NULL)
goto invalid;
len = strlen(attr);
if (len == 0)
goto invalid;
for (i = 0; uev->envp[i] != NULL; i++) {
const char *var = uev->envp[i];
if (strlen(var) > len &&
!memcmp(var, attr, len) && var[len] == '=') {
p = var + len + 1;
break;
}
}
condlog(4, "%s: %s -> '%s'", __func__, attr, p);
return p;
invalid:
condlog(2, "%s: empty variable name", __func__);
return NULL;
}
static int uevent_get_env_positive_int(const struct uevent *uev,
const char *attr)
{
const char *p = uevent_get_env_var(uev, attr);
char *q;
int ret;
if (p == NULL || *p == '\0')
return -1;
ret = strtoul(p, &q, 10);
if (*q != '\0' || ret < 0) {
condlog(2, "%s: invalid %s: '%s'", __func__, attr, p);
return -1;
}
return ret;
}
void
uevent_get_wwid(struct uevent *uev)
{
char *uid_attribute;
const char *val;
struct config * conf;
conf = get_multipath_config();
pthread_cleanup_push(put_multipath_config, conf);
uid_attribute = get_uid_attribute_by_attrs(conf, uev->kernel);
pthread_cleanup_pop(1);
val = uevent_get_env_var(uev, uid_attribute);
if (val)
uev->wwid = val;
}
bool
uevent_need_merge(void)
{
struct config * conf;
bool need_merge = false;
conf = get_multipath_config();
if (VECTOR_SIZE(&conf->uid_attrs) > 0)
need_merge = true;
put_multipath_config(conf);
return need_merge;
}
bool
uevent_can_discard(struct uevent *uev)
{
int invalid = 0;
struct config * conf;
/*
* do not filter dm devices by devnode
*/
if (!strncmp(uev->kernel, "dm-", 3))
return false;
/*
* filter paths devices by devnode
*/
conf = get_multipath_config();
pthread_cleanup_push(put_multipath_config, conf);
if (filter_devnode(conf->blist_devnode, conf->elist_devnode,
uev->kernel) > 0)
invalid = 1;
pthread_cleanup_pop(1);
if (invalid)
return true;
return false;
}
bool
uevent_can_filter(struct uevent *earlier, struct uevent *later)
{
/*
* filter earlier uvents if path has removed later. Eg:
* "add path1 |chang path1 |add path2 |remove path1"
* can filter as:
* "add path2 |remove path1"
* uevents "add path1" and "chang path1" are filtered out
*/
if (!strcmp(earlier->kernel, later->kernel) &&
!strcmp(later->action, "remove") &&
strncmp(later->kernel, "dm-", 3)) {
return true;
}
/*
* filter change uvents if add uevents exist. Eg:
* "change path1| add path1 |add path2"
* can filter as:
* "add path1 |add path2"
* uevent "chang path1" is filtered out
*/
if (!strcmp(earlier->kernel, later->kernel) &&
!strcmp(earlier->action, "change") &&
!strcmp(later->action, "add") &&
strncmp(later->kernel, "dm-", 3)) {
return true;
}
return false;
}
bool
merge_need_stop(struct uevent *earlier, struct uevent *later)
{
/*
* dm uevent do not try to merge with left uevents
*/
if (!strncmp(later->kernel, "dm-", 3))
return true;
/*
* we can not make a jugement without wwid,
* so it is sensible to stop merging
*/
if (!earlier->wwid || !later->wwid)
return true;
/*
* uevents merging stopped
* when we meet an opposite action uevent from the same LUN to AVOID
* "add path1 |remove path1 |add path2 |remove path2 |add path3"
* to merge as "remove path1, path2" and "add path1, path2, path3"
* OR
* "remove path1 |add path1 |remove path2 |add path2 |remove path3"
* to merge as "add path1, path2" and "remove path1, path2, path3"
* SO
* when we meet a non-change uevent from the same LUN
* with the same wwid and different action
* it would be better to stop merging.
*/
if (!strcmp(earlier->wwid, later->wwid) &&
strcmp(earlier->action, later->action) &&
strcmp(earlier->action, "change") &&
strcmp(later->action, "change"))
return true;
return false;
}
bool
uevent_can_merge(struct uevent *earlier, struct uevent *later)
{
/* merge paths uevents
* whose wwids exsit and are same
* and actions are same,
* and actions are addition or deletion
*/
if (earlier->wwid && later->wwid &&
!strcmp(earlier->wwid, later->wwid) &&
!strcmp(earlier->action, later->action) &&
strncmp(earlier->action, "change", 6) &&
strncmp(earlier->kernel, "dm-", 3)) {
return true;
}
return false;
}
void
uevent_prepare(struct list_head *tmpq)
{
struct uevent *uev, *tmp;
list_for_each_entry_reverse_safe(uev, tmp, tmpq, node) {
if (uevent_can_discard(uev)) {
list_del_init(&uev->node);
if (uev->udev)
udev_device_unref(uev->udev);
FREE(uev);
continue;
}
if (strncmp(uev->kernel, "dm-", 3) &&
uevent_need_merge())
uevent_get_wwid(uev);
}
}
void
uevent_filter(struct uevent *later, struct list_head *tmpq)
{
struct uevent *earlier, *tmp;
list_for_some_entry_reverse_safe(earlier, tmp, &later->node, tmpq, node) {
/*
* filter unnessary earlier uevents
* by the later uevent
*/
if (uevent_can_filter(earlier, later)) {
condlog(3, "uevent: %s-%s has filtered by uevent: %s-%s",
earlier->kernel, earlier->action,
later->kernel, later->action);
list_del_init(&earlier->node);
if (earlier->udev)
udev_device_unref(earlier->udev);
FREE(earlier);
}
}
}
void
uevent_merge(struct uevent *later, struct list_head *tmpq)
{
struct uevent *earlier, *tmp;
list_for_some_entry_reverse_safe(earlier, tmp, &later->node, tmpq, node) {
if (merge_need_stop(earlier, later))
break;
/*
* merge earlier uevents to the later uevent
*/
if (uevent_can_merge(earlier, later)) {
condlog(3, "merged uevent: %s-%s-%s with uevent: %s-%s-%s",
earlier->action, earlier->kernel, earlier->wwid,
later->action, later->kernel, later->wwid);
list_move(&earlier->node, &later->merge_node);
}
}
}
void
merge_uevq(struct list_head *tmpq)
{
struct uevent *later;
uevent_prepare(tmpq);
list_for_each_entry_reverse(later, tmpq, node) {
uevent_filter(later, tmpq);
if(uevent_need_merge())
uevent_merge(later, tmpq);
}
}
void
service_uevq(struct list_head *tmpq)
{
struct uevent *uev, *tmp;
list_for_each_entry_safe(uev, tmp, tmpq, node) {
list_del_init(&uev->node);
if (my_uev_trigger && my_uev_trigger(uev, my_trigger_data))
condlog(0, "uevent trigger error");
uevq_cleanup(&uev->merge_node);
if (uev->udev)
udev_device_unref(uev->udev);
FREE(uev);
}
}
static void uevent_cleanup(void *arg)
{
struct udev *udev = arg;
condlog(3, "Releasing uevent_listen() resources");
udev_unref(udev);
}
static void monitor_cleanup(void *arg)
{
struct udev_monitor *monitor = arg;
condlog(3, "Releasing uevent_monitor() resources");
udev_monitor_unref(monitor);
}
/*
* Service the uevent queue.
*/
int uevent_dispatch(int (*uev_trigger)(struct uevent *, void * trigger_data),
void * trigger_data)
{
my_uev_trigger = uev_trigger;
my_trigger_data = trigger_data;
mlockall(MCL_CURRENT | MCL_FUTURE);
while (1) {
LIST_HEAD(uevq_tmp);
pthread_mutex_lock(uevq_lockp);
servicing_uev = 0;
/*
* Condition signals are unreliable,
* so make sure we only wait if we have to.
*/
if (list_empty(&uevq)) {
pthread_cond_wait(uev_condp, uevq_lockp);
}
servicing_uev = 1;
list_splice_init(&uevq, &uevq_tmp);
pthread_mutex_unlock(uevq_lockp);
if (!my_uev_trigger)
break;
merge_uevq(&uevq_tmp);
service_uevq(&uevq_tmp);
}
condlog(3, "Terminating uev service queue");
uevq_cleanup(&uevq);
return 0;
}
struct uevent *uevent_from_buffer(char *buf, ssize_t buflen)
{
struct uevent *uev;
char *buffer;
size_t bufpos;
int i;
char *pos;
uev = alloc_uevent();
if (!uev) {
condlog(1, "lost uevent, oom");
return NULL;
}
if ((size_t)buflen > sizeof(buf)-1)
buflen = sizeof(buf)-1;
/*
* Copy the shared receive buffer contents to buffer private
* to this uevent so we can immediately reuse the shared buffer.
*/
memcpy(uev->buffer, buf, HOTPLUG_BUFFER_SIZE + OBJECT_SIZE);
buffer = uev->buffer;
buffer[buflen] = '\0';
/* save start of payload */
bufpos = strlen(buffer) + 1;
/* action string */
uev->action = buffer;
pos = strchr(buffer, '@');
if (!pos) {
condlog(3, "bad action string '%s'", buffer);
FREE(uev);
return NULL;
}
pos[0] = '\0';
/* sysfs path */
uev->devpath = &pos[1];
/* hotplug events have the environment attached - reconstruct envp[] */
for (i = 0; (bufpos < (size_t)buflen) && (i < HOTPLUG_NUM_ENVP-1); i++) {
int keylen;
char *key;
key = &buffer[bufpos];
keylen = strlen(key);
uev->envp[i] = key;
/* Filter out sequence number */
if (strncmp(key, "SEQNUM=", 7) == 0) {
char *eptr;
uev->seqnum = strtoul(key + 7, &eptr, 10);
if (eptr == key + 7)
uev->seqnum = -1;
}
bufpos += keylen + 1;
}
uev->envp[i] = NULL;
condlog(3, "uevent %ld '%s' from '%s'", uev->seqnum,
uev->action, uev->devpath);
uev->kernel = strrchr(uev->devpath, '/');
if (uev->kernel)
uev->kernel++;
/* print payload environment */
for (i = 0; uev->envp[i] != NULL; i++)
condlog(5, "%s", uev->envp[i]);
return uev;
}
int failback_listen(void)
{
int sock;
struct sockaddr_nl snl;
struct sockaddr_un sun;
socklen_t addrlen;
int retval;
int rcvbufsz = 128*1024;
int rcvsz = 0;
int rcvszsz = sizeof(rcvsz);
unsigned int *prcvszsz = (unsigned int *)&rcvszsz;
const int feature_on = 1;
/*
* First check whether we have a udev socket
*/
memset(&sun, 0x00, sizeof(struct sockaddr_un));
sun.sun_family = AF_LOCAL;
strcpy(&sun.sun_path[1], "/org/kernel/dm/multipath_event");
addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(sun.sun_path+1) + 1;
sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
if (sock >= 0) {
condlog(3, "reading events from udev socket.");
/* the bind takes care of ensuring only one copy running */
retval = bind(sock, (struct sockaddr *) &sun, addrlen);
if (retval < 0) {
condlog(0, "bind failed, exit");
goto exit;
}
/* enable receiving of the sender credentials */
retval = setsockopt(sock, SOL_SOCKET, SO_PASSCRED,
&feature_on, sizeof(feature_on));
if (retval < 0) {
condlog(0, "failed to enable credential passing, exit");
goto exit;
}
} else {
/* Fallback to read kernel netlink events */
memset(&snl, 0x00, sizeof(struct sockaddr_nl));
snl.nl_family = AF_NETLINK;
snl.nl_pid = getpid();
snl.nl_groups = 0x01;
sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
if (sock == -1) {
condlog(0, "error getting socket, exit");
return 1;
}
condlog(3, "reading events from kernel.");
/*
* try to avoid dropping uevents, even so, this is not a guarantee,
* but it does help to change the netlink uevent socket's
* receive buffer threshold from the default value of 106,496 to
* the maximum value of 262,142.
*/
retval = setsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvbufsz,
sizeof(rcvbufsz));
if (retval < 0) {
condlog(0, "error setting receive buffer size for socket, exit");
exit(1);
}
retval = getsockopt(sock, SOL_SOCKET, SO_RCVBUF, &rcvsz, prcvszsz);
if (retval < 0) {
condlog(0, "error setting receive buffer size for socket, exit");
exit(1);
}
condlog(3, "receive buffer size for socket is %u.", rcvsz);
/* enable receiving of the sender credentials */
if (setsockopt(sock, SOL_SOCKET, SO_PASSCRED,
&feature_on, sizeof(feature_on)) < 0) {
condlog(0, "error on enabling credential passing for socket");
exit(1);
}
retval = bind(sock, (struct sockaddr *) &snl,
sizeof(struct sockaddr_nl));
if (retval < 0) {
condlog(0, "bind failed, exit");
goto exit;
}
}
while (1) {
size_t bufpos;
ssize_t buflen;
struct uevent *uev;
struct msghdr smsg;
struct iovec iov;
char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
struct cmsghdr *cmsg;
struct ucred *cred;
static char buf[HOTPLUG_BUFFER_SIZE + OBJECT_SIZE];
memset(buf, 0x00, sizeof(buf));
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);
buflen = recvmsg(sock, &smsg, 0);
if (buflen < 0) {
if (errno != EINTR)
condlog(0, "error receiving message, errno %d", errno);
continue;
}
cmsg = CMSG_FIRSTHDR(&smsg);
if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
condlog(3, "no sender credentials received, message ignored");
continue;
}
cred = (struct ucred *)CMSG_DATA(cmsg);
if (cred->uid != 0) {
condlog(3, "sender uid=%d, message ignored", cred->uid);
continue;
}
/* skip header */
bufpos = strlen(buf) + 1;
if (bufpos < sizeof("a@/d") || bufpos >= sizeof(buf)) {
condlog(3, "invalid message length");
continue;
}
/* check message header */
if (strstr(buf, "@/") == NULL) {
condlog(3, "unrecognized message header");
continue;
}
if ((size_t)buflen > sizeof(buf)-1) {
condlog(2, "buffer overflow for received uevent");
buflen = sizeof(buf)-1;
}
uev = uevent_from_buffer(buf, buflen);
if (!uev)
continue;
/*
* Queue uevent and poke service pthread.
*/
pthread_mutex_lock(uevq_lockp);
list_add_tail(&uev->node, &uevq);
pthread_cond_signal(uev_condp);
pthread_mutex_unlock(uevq_lockp);
}
exit:
close(sock);
return 1;
}
struct uevent *uevent_from_udev_device(struct udev_device *dev)
{
struct uevent *uev;
int i = 0;
char *pos, *end;
struct udev_list_entry *list_entry;
uev = alloc_uevent();
if (!uev) {
udev_device_unref(dev);
condlog(1, "lost uevent, oom");
return NULL;
}
pos = uev->buffer;
end = pos + HOTPLUG_BUFFER_SIZE + OBJECT_SIZE - 1;
udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(dev)) {
const char *name, *value;
int bytes;
name = udev_list_entry_get_name(list_entry);
if (!name)
name = "(null)";
value = udev_list_entry_get_value(list_entry);
if (!value)
value = "(null)";
bytes = snprintf(pos, end - pos, "%s=%s", name, value);
if (pos + bytes >= end) {
condlog(2, "buffer overflow for uevent");
break;
}
uev->envp[i] = pos;
pos += bytes;
*pos = '\0';
pos++;
if (strcmp(name, "DEVPATH") == 0)
uev->devpath = uev->envp[i] + 8;
if (strcmp(name, "ACTION") == 0)
uev->action = uev->envp[i] + 7;
i++;
if (i == HOTPLUG_NUM_ENVP - 1)
break;
}
if (!uev->devpath || ! uev->action) {
udev_device_unref(dev);
condlog(1, "uevent missing necessary fields");
FREE(uev);
return NULL;
}
uev->udev = dev;
uev->envp[i] = NULL;
condlog(3, "uevent '%s' from '%s'", uev->action, uev->devpath);
uev->kernel = strrchr(uev->devpath, '/');
if (uev->kernel)
uev->kernel++;
/* print payload environment */
for (i = 0; uev->envp[i] != NULL; i++)
condlog(5, "%s", uev->envp[i]);
return uev;
}
bool uevent_burst(struct timeval *start_time, int events)
{
struct timeval diff_time, end_time;
unsigned long speed;
unsigned long eclipse_ms;
if(events > MAX_ACCUMULATION_COUNT) {
condlog(2, "burst got %u uevents, too much uevents, stopped", events);
return false;
}
gettimeofday(&end_time, NULL);
timersub(&end_time, start_time, &diff_time);
eclipse_ms = diff_time.tv_sec * 1000 + diff_time.tv_usec / 1000;
if (eclipse_ms == 0)
return true;
if (eclipse_ms > MAX_ACCUMULATION_TIME) {
condlog(2, "burst continued %lu ms, too long time, stopped", eclipse_ms);
return false;
}
speed = (events * 1000) / eclipse_ms;
if (speed > MIN_BURST_SPEED)
return true;
return false;
}
int uevent_listen(struct udev *udev)
{
int err = 2;
struct udev_monitor *monitor = NULL;
int fd, socket_flags, events;
struct timeval start_time;
int need_failback = 1;
int timeout = 30;
LIST_HEAD(uevlisten_tmp);
/*
* Queue uevents for service by dedicated thread so that the uevent
* listening thread does not block on multipathd locks (vecs->lock)
* thereby not getting to empty the socket's receive buffer queue
* often enough.
*/
if (!udev) {
condlog(1, "no udev context");
return 1;
}
udev_ref(udev);
pthread_cleanup_push(uevent_cleanup, udev);
monitor = udev_monitor_new_from_netlink(udev, "udev");
if (!monitor) {
condlog(2, "failed to create udev monitor");
goto failback;
}
pthread_cleanup_push(monitor_cleanup, monitor);
#ifdef LIBUDEV_API_RECVBUF
if (udev_monitor_set_receive_buffer_size(monitor, 128 * 1024 * 1024))
condlog(2, "failed to increase buffer size");
#endif
fd = udev_monitor_get_fd(monitor);
if (fd < 0) {
condlog(2, "failed to get monitor fd");
goto out;
}
socket_flags = fcntl(fd, F_GETFL);
if (socket_flags < 0) {
condlog(2, "failed to get monitor socket flags : %s",
strerror(errno));
goto out;
}
if (fcntl(fd, F_SETFL, socket_flags & ~O_NONBLOCK) < 0) {
condlog(2, "failed to set monitor socket flags : %s",
strerror(errno));
goto out;
}
err = udev_monitor_filter_add_match_subsystem_devtype(monitor, "block",
"disk");
if (err)
condlog(2, "failed to create filter : %s", strerror(-err));
err = udev_monitor_enable_receiving(monitor);
if (err) {
condlog(2, "failed to enable receiving : %s", strerror(-err));
goto out;
}
events = 0;
gettimeofday(&start_time, NULL);
while (1) {
struct uevent *uev;
struct udev_device *dev;
struct pollfd ev_poll;
int poll_timeout;
int fdcount;
memset(&ev_poll, 0, sizeof(struct pollfd));
ev_poll.fd = fd;
ev_poll.events = POLLIN;
poll_timeout = timeout * 1000;
errno = 0;
fdcount = poll(&ev_poll, 1, poll_timeout);
if (fdcount > 0 && ev_poll.revents & POLLIN) {
timeout = uevent_burst(&start_time, events + 1) ? 1 : 0;
dev = udev_monitor_receive_device(monitor);
if (!dev) {
condlog(0, "failed getting udev device");
continue;
}
uev = uevent_from_udev_device(dev);
if (!uev)
continue;
list_add_tail(&uev->node, &uevlisten_tmp);
events++;
continue;
}
if (fdcount < 0) {
if (errno == EINTR)
continue;
condlog(0, "error receiving "
"uevent message: %m");
err = -errno;
break;
}
if (!list_empty(&uevlisten_tmp)) {
/*
* Queue uevents and poke service pthread.
*/
condlog(3, "Forwarding %d uevents", events);
pthread_mutex_lock(uevq_lockp);
list_splice_tail_init(&uevlisten_tmp, &uevq);
pthread_cond_signal(uev_condp);
pthread_mutex_unlock(uevq_lockp);
events = 0;
}
gettimeofday(&start_time, NULL);
timeout = 30;
}
need_failback = 0;
out:
pthread_cleanup_pop(1);
failback:
if (need_failback)
err = failback_listen();
pthread_cleanup_pop(1);
return err;
}
int uevent_get_major(const struct uevent *uev)
{
return uevent_get_env_positive_int(uev, "MAJOR");
}
int uevent_get_minor(const struct uevent *uev)
{
return uevent_get_env_positive_int(uev, "MINOR");
}
int uevent_get_disk_ro(const struct uevent *uev)
{
return uevent_get_env_positive_int(uev, "DISK_RO");
}
static char *uevent_get_dm_str(const struct uevent *uev, char *attr)
{
const char *tmp = uevent_get_env_var(uev, attr);
if (tmp == NULL)
return NULL;
return strdup(tmp);
}
char *uevent_get_dm_name(const struct uevent *uev)
{
return uevent_get_dm_str(uev, "DM_NAME");
}
char *uevent_get_dm_path(const struct uevent *uev)
{
return uevent_get_dm_str(uev, "DM_PATH");
}
char *uevent_get_dm_action(const struct uevent *uev)
{
return uevent_get_dm_str(uev, "DM_ACTION");
}
bool uevent_is_mpath(const struct uevent *uev)
{
const char *uuid = uevent_get_env_var(uev, "DM_UUID");
if (uuid == NULL)
return false;
if (strncmp(uuid, UUID_PREFIX, UUID_PREFIX_LEN))
return false;
return uuid[UUID_PREFIX_LEN] != '\0';
}