2 * udevd.c - hotplug event serializer
4 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
5 * Copyright (C) 2004 Chris Friesen <chris_friesen@sympatico.ca>
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the
10 * Free Software Foundation version 2 of the License.
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 675 Mass Ave, Cambridge, MA 02139, USA.
32 #include <sys/types.h>
33 #include <sys/socket.h>
36 #include <sys/sysinfo.h>
42 #include "udev_version.h"
46 static int pipefds[2];
47 static unsigned long long expected_seqnum = 0;
48 static volatile int sigchilds_waiting;
49 static volatile int run_msg_q;
50 static volatile int sig_flag;
51 static int run_exec_q;
53 static LIST_HEAD(msg_list);
54 static LIST_HEAD(exec_list);
55 static LIST_HEAD(running_list);
57 static void exec_queue_manager(void);
58 static void msg_queue_manager(void);
59 static void user_sighandler(void);
60 static void reap_sigchilds(void);
64 unsigned char logname[LOGNAME_SIZE];
65 void log_message (int level, const char *format, ...)
69 va_start(args, format);
70 vsyslog(level, format, args);
75 #define msg_dump(msg) \
76 dbg("msg_dump: sequence %llu, '%s', '%s', '%s'", \
77 msg->seqnum, msg->action, msg->devpath, msg->subsystem);
79 static void msg_dump_queue(void)
82 struct hotplug_msg *msg;
84 list_for_each_entry(msg, &msg_list, list)
85 dbg("sequence %llu in queue", msg->seqnum);
89 static struct hotplug_msg *msg_create(void)
91 struct hotplug_msg *new_msg;
93 new_msg = malloc(sizeof(struct hotplug_msg));
99 static void run_queue_delete(struct hotplug_msg *msg)
101 list_del(&msg->list);
105 /* orders the message in the queue by sequence number */
106 static void msg_queue_insert(struct hotplug_msg *msg)
108 struct hotplug_msg *loop_msg;
111 /* sort message by sequence number into list. events
112 * will tend to come in order, so scan the list backwards
114 list_for_each_entry_reverse(loop_msg, &msg_list, list)
115 if (loop_msg->seqnum < msg->seqnum)
118 /* store timestamp of queuing */
120 msg->queue_time = info.uptime;
122 list_add(&msg->list, &loop_msg->list);
123 dbg("queued message seq %llu", msg->seqnum);
125 /* run msg queue manager */
131 /* forks event and removes event from run queue when finished */
132 static void udev_run(struct hotplug_msg *msg)
135 char action[ACTION_SIZE];
136 char devpath[DEVPATH_SIZE];
137 char seqnum[SEQNUM_SIZE];
138 char *env[] = { action, devpath, seqnum, NULL };
140 snprintf(action, ACTION_SIZE-1, "ACTION=%s", msg->action);
141 action[ACTION_SIZE-1] = '\0';
142 snprintf(devpath, DEVPATH_SIZE-1, "DEVPATH=%s", msg->devpath);
143 devpath[DEVPATH_SIZE-1] = '\0';
144 sprintf(seqnum, "SEQNUM=%llu", msg->seqnum);
150 execle(udev_bin, "udev", msg->subsystem, NULL, env);
151 dbg("exec of child failed");
155 dbg("fork of child failed");
156 run_queue_delete(msg);
157 /* note: we never managed to run, so we had no impact on
158 * running_with_devpath(), so don't bother setting run_exec_q
162 /* get SIGCHLD in main loop */
163 dbg("==> exec seq %llu [%d] working at '%s'", msg->seqnum, pid, msg->devpath);
168 /* returns already running task with devpath */
169 static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
171 struct hotplug_msg *loop_msg;
172 list_for_each_entry(loop_msg, &running_list, list)
173 if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
178 /* exec queue management routine executes the events and delays events for the same devpath */
179 static void exec_queue_manager(void)
181 struct hotplug_msg *loop_msg;
182 struct hotplug_msg *tmp_msg;
183 struct hotplug_msg *msg;
185 list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
186 msg = running_with_devpath(loop_msg);
188 /* move event to run list */
189 list_move_tail(&loop_msg->list, &running_list);
191 dbg("moved seq %llu to running list", loop_msg->seqnum);
193 dbg("delay seq %llu, cause seq %llu already working on '%s'",
194 loop_msg->seqnum, msg->seqnum, msg->devpath);
199 static void msg_move_exec(struct hotplug_msg *msg)
201 list_move_tail(&msg->list, &exec_list);
203 expected_seqnum = msg->seqnum+1;
204 dbg("moved seq %llu to exec, next expected is %llu",
205 msg->seqnum, expected_seqnum);
208 /* msg queue management routine handles the timeouts and dispatches the events */
209 static void msg_queue_manager(void)
211 struct hotplug_msg *loop_msg;
212 struct hotplug_msg *tmp_msg;
216 dbg("msg queue manager, next expected is %llu", expected_seqnum);
218 list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
219 /* move event with expected sequence to the exec list */
220 if (loop_msg->seqnum == expected_seqnum) {
221 msg_move_exec(loop_msg);
225 /* move event with expired timeout to the exec list */
227 msg_age = info.uptime - loop_msg->queue_time;
228 dbg("seq %llu is %li seconds old", loop_msg->seqnum, msg_age);
229 if (msg_age > EVENT_TIMEOUT_SEC-1) {
230 msg_move_exec(loop_msg);
239 /* set timeout for remaining queued events */
240 if (list_empty(&msg_list) == 0) {
241 struct itimerval itv = {{0, 0}, {EVENT_TIMEOUT_SEC - msg_age, 0}};
242 dbg("next event expires in %li seconds", EVENT_TIMEOUT_SEC - msg_age);
243 setitimer(ITIMER_REAL, &itv, NULL);
247 /* receive the msg, do some basic sanity checks, and queue it */
248 static void handle_msg(int sock)
250 struct hotplug_msg *msg;
253 struct cmsghdr *cmsg;
256 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
260 dbg("unable to store message");
265 iov.iov_len = sizeof(struct hotplug_msg);
267 memset(&smsg, 0x00, sizeof(struct msghdr));
270 smsg.msg_control = cred_msg;
271 smsg.msg_controllen = sizeof(cred_msg);
273 retval = recvmsg(sock, &smsg, 0);
276 dbg("unable to receive message");
279 cmsg = CMSG_FIRSTHDR(&smsg);
280 cred = (struct ucred *) CMSG_DATA(cmsg);
282 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
283 dbg("no sender credentials received, message ignored");
287 if (cred->uid != 0) {
288 dbg("sender uid=%i, message ignored", cred->uid);
292 if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
293 dbg("message magic '%s' doesn't match, ignore it", msg->magic);
297 /* if no seqnum is given, we move straight to exec queue */
298 if (msg->seqnum == 0) {
299 list_add(&msg->list, &exec_list);
302 msg_queue_insert(msg);
311 static void asmlinkage sig_handler(int signum)
321 /* set flag, then write to pipe if needed */
326 /* set flag, then write to pipe if needed */
327 sigchilds_waiting = 1;
331 dbg("unhandled signal %d", signum);
336 /* if pipe is empty, write to pipe to force select to return
337 * immediately when it gets called
340 rc = write(pipefds[1],&signum,sizeof(signum));
342 dbg("unable to write to pipe");
348 static void udev_done(int pid)
350 /* find msg associated with pid and delete it */
351 struct hotplug_msg *msg;
353 list_for_each_entry(msg, &running_list, list) {
354 if (msg->pid == pid) {
355 dbg("<== exec seq %llu came back", msg->seqnum);
356 run_queue_delete(msg);
358 /* we want to run the exec queue manager since there may
359 * be events waiting with the devpath of the one that
368 static void reap_sigchilds(void)
371 int pid = waitpid(-1, NULL, WNOHANG);
372 if ((pid == -1) || (pid == 0))
378 /* just read everything from the pipe and clear the flag,
379 * the flags was set in the signal handler
381 static void user_sighandler(void)
385 int rc = read(pipefds[0], &sig, sizeof(sig));
393 int main(int argc, char *argv[], char *envp[])
395 int ssock, maxsockplus;
396 struct sockaddr_un saddr;
399 const int feature_on = 1;
400 struct sigaction act;
403 logging_init("udevd");
404 dbg("version %s", UDEV_VERSION);
407 dbg("need to be root, exit");
411 /* make sure we don't lock any path */
413 umask(umask(077) | 022);
415 /* Set fds to dev/null */
416 fd = open( "/dev/null", O_RDWR );
418 dbg("error opening /dev/null %s", strerror(errno));
427 /* become session leader */
430 /* setup signal handler pipe */
431 retval = pipe(pipefds);
433 dbg("error getting pipes: %s", strerror(errno));
437 retval = fcntl(pipefds[0], F_SETFL, O_NONBLOCK);
439 dbg("error fcntl on read pipe: %s", strerror(errno));
442 retval = fcntl(pipefds[0], F_SETFD, FD_CLOEXEC);
444 dbg("error fcntl on read pipe: %s", strerror(errno));
448 retval = fcntl(pipefds[1], F_SETFL, O_NONBLOCK);
450 dbg("error fcntl on write pipe: %s", strerror(errno));
453 retval = fcntl(pipefds[1], F_SETFD, FD_CLOEXEC);
455 dbg("error fcntl on write pipe: %s", strerror(errno));
459 /* set signal handlers */
460 act.sa_handler = (void (*) (int))sig_handler;
461 sigemptyset(&act.sa_mask);
462 act.sa_flags = SA_RESTART;
463 sigaction(SIGINT, &act, NULL);
464 sigaction(SIGTERM, &act, NULL);
465 sigaction(SIGALRM, &act, NULL);
466 sigaction(SIGCHLD, &act, NULL);
468 memset(&saddr, 0x00, sizeof(saddr));
469 saddr.sun_family = AF_LOCAL;
470 /* use abstract namespace for socket path */
471 strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
472 addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
474 ssock = socket(AF_LOCAL, SOCK_DGRAM, 0);
476 dbg("error getting socket, exit");
480 set_cloexec_flag(ssock, 1);
482 /* the bind takes care of ensuring only one copy running */
483 retval = bind(ssock, (struct sockaddr *) &saddr, addrlen);
485 dbg("bind failed, exit");
488 retval = fcntl(ssock, F_SETFD, FD_CLOEXEC);
490 dbg("error fcntl on ssock: %s", strerror(errno));
494 /* enable receiving of the sender credentials */
495 setsockopt(ssock, SOL_SOCKET, SO_PASSCRED, &feature_on, sizeof(feature_on));
497 /* possible override of udev binary, used for testing */
498 udev_bin = getenv("UDEV_BIN");
499 if (udev_bin != NULL)
500 dbg("udev binary is set to '%s'", udev_bin);
505 FD_SET(ssock, &readfds);
506 FD_SET(pipefds[0], &readfds);
507 maxsockplus = ssock+1;
509 fd_set workreadfds = readfds;
510 retval = select(maxsockplus, &workreadfds, NULL, NULL, NULL);
514 dbg("error in select: %s", strerror(errno));
518 if (FD_ISSET(ssock, &workreadfds))
521 if (FD_ISSET(pipefds[0], &workreadfds))
524 if (sigchilds_waiting) {
525 sigchilds_waiting = 0;
535 /* clean up running_list before calling exec_queue_manager() */
536 if (sigchilds_waiting) {
537 sigchilds_waiting = 0;
542 exec_queue_manager();