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 "klibc_fixups.h"
38 #include <sys/sysinfo.h>
44 #include "udev_version.h"
48 static int pipefds[2];
49 static int expected_seqnum = 0;
50 volatile static int children_waiting;
51 volatile static int run_msg_q;
52 volatile static int sig_flag;
53 static int run_exec_q;
55 static LIST_HEAD(msg_list);
56 static LIST_HEAD(exec_list);
57 static LIST_HEAD(running_list);
59 static void exec_queue_manager(void);
60 static void msg_queue_manager(void);
61 static void user_sighandler(void);
62 static void reap_kids(void);
65 unsigned char logname[LOGNAME_SIZE];
66 void log_message (int level, const char *format, ...)
70 va_start(args, format);
71 vsyslog(level, format, args);
76 static void msg_dump_queue(void)
79 struct hotplug_msg *msg;
81 list_for_each_entry(msg, &msg_list, list)
82 dbg("sequence %d in queue", msg->seqnum);
86 static void msg_dump(struct hotplug_msg *msg)
88 dbg("sequence %d, '%s', '%s', '%s'",
89 msg->seqnum, msg->action, msg->devpath, msg->subsystem);
92 static struct hotplug_msg *msg_create(void)
94 struct hotplug_msg *new_msg;
96 new_msg = malloc(sizeof(struct hotplug_msg));
102 static void run_queue_delete(struct hotplug_msg *msg)
104 list_del(&msg->list);
108 /* orders the message in the queue by sequence number */
109 static void msg_queue_insert(struct hotplug_msg *msg)
111 struct hotplug_msg *loop_msg;
114 /* sort message by sequence number into list. events
115 * will tend to come in order, so scan the list backwards
117 list_for_each_entry_reverse(loop_msg, &msg_list, list)
118 if (loop_msg->seqnum < msg->seqnum)
121 /* store timestamp of queuing */
123 msg->queue_time = info.uptime;
125 list_add(&msg->list, &loop_msg->list);
126 dbg("queued message seq %d", msg->seqnum);
128 /* run msg queue manager */
134 /* forks event and removes event from run queue when finished */
135 static void udev_run(struct hotplug_msg *msg)
138 char action[ACTION_SIZE];
139 char devpath[DEVPATH_SIZE];
140 char *env[] = { action, devpath, NULL };
142 snprintf(action, sizeof(action), "ACTION=%s", msg->action);
143 snprintf(devpath, sizeof(devpath), "DEVPATH=%s", msg->devpath);
149 execle(UDEV_BIN, "udev", msg->subsystem, NULL, env);
150 dbg("exec of child failed");
154 dbg("fork of child failed");
155 run_queue_delete(msg);
156 /* note: we never managed to run, so we had no impact on
157 * running_with_devpath(), so don't bother setting run_exec_q
161 /* get SIGCHLD in main loop */
162 dbg("==> exec seq %d [%d] working at '%s'", msg->seqnum, pid, msg->devpath);
167 /* returns already running task with devpath */
168 static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
170 struct hotplug_msg *loop_msg;
171 list_for_each_entry(loop_msg, &running_list, list)
172 if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
177 /* exec queue management routine executes the events and delays events for the same devpath */
178 static void exec_queue_manager()
180 struct hotplug_msg *loop_msg;
181 struct hotplug_msg *tmp_msg;
182 struct hotplug_msg *msg;
184 list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
185 msg = running_with_devpath(loop_msg);
187 /* move event to run list */
188 list_move_tail(&loop_msg->list, &running_list);
190 dbg("moved seq %d to running list", loop_msg->seqnum);
192 dbg("delay seq %d, cause seq %d already working on '%s'",
193 loop_msg->seqnum, msg->seqnum, msg->devpath);
198 static void msg_move_exec(struct hotplug_msg *msg)
200 list_move_tail(&msg->list, &exec_list);
202 expected_seqnum = msg->seqnum+1;
203 dbg("moved seq %d to exec, next expected is %d",
204 msg->seqnum, expected_seqnum);
207 /* msg queue management routine handles the timeouts and dispatches the events */
208 static void msg_queue_manager()
210 struct hotplug_msg *loop_msg;
211 struct hotplug_msg *tmp_msg;
215 dbg("msg queue manager, next expected is %d", expected_seqnum);
217 list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
218 /* move event with expected sequence to the exec list */
219 if (loop_msg->seqnum == expected_seqnum) {
220 msg_move_exec(loop_msg);
224 /* move event with expired timeout to the exec list */
226 msg_age = info.uptime - loop_msg->queue_time;
227 dbg("seq %d is %li seconds old", loop_msg->seqnum, msg_age);
228 if (msg_age > EVENT_TIMEOUT_SEC-1) {
229 msg_move_exec(loop_msg);
238 /* set timeout for remaining queued events */
239 if (list_empty(&msg_list) == 0) {
240 struct itimerval itv = {{0, 0}, {EVENT_TIMEOUT_SEC - msg_age, 0}};
241 dbg("next event expires in %li seconds", EVENT_TIMEOUT_SEC - msg_age);
242 setitimer(ITIMER_REAL, &itv, 0);
246 /* receive the msg, do some basic sanity checks, and queue it */
247 static void handle_msg(int sock)
249 struct hotplug_msg *msg;
252 struct cmsghdr *cmsg;
255 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
259 dbg("unable to store message");
264 iov.iov_len = sizeof(struct hotplug_msg);
266 memset(&smsg, 0x00, sizeof(struct msghdr));
269 smsg.msg_control = cred_msg;
270 smsg.msg_controllen = sizeof(cred_msg);
272 retval = recvmsg(sock, &smsg, 0);
275 dbg("unable to receive message");
278 cmsg = CMSG_FIRSTHDR(&smsg);
279 cred = (struct ucred *) CMSG_DATA(cmsg);
281 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
282 dbg("no sender credentials received, message ignored");
286 if (cred->uid != 0) {
287 dbg("sender uid=%i, message ignored", cred->uid);
291 if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
292 dbg("message magic '%s' doesn't match, ignore it", msg->magic);
296 /* if no seqnum is given, we move straight to exec queue */
297 if (msg->seqnum == -1) {
298 list_add(&msg->list, &exec_list);
301 msg_queue_insert(msg);
310 static void sig_handler(int signum)
319 /* set flag, then write to pipe if needed */
324 /* set flag, then write to pipe if needed */
325 children_waiting = 1;
329 dbg("unhandled signal");
334 /* if pipe is empty, write to pipe to force select to return
335 * immediately when it gets called
338 rc = write(pipefds[1],&signum,sizeof(signum));
340 dbg("unable to write to pipe");
346 static void udev_done(int pid)
348 /* find msg associated with pid and delete it */
349 struct hotplug_msg *msg;
351 list_for_each_entry(msg, &running_list, list) {
352 if (msg->pid == pid) {
353 dbg("<== exec seq %d came back", msg->seqnum);
354 run_queue_delete(msg);
356 /* we want to run the exec queue manager since there may
357 * be events waiting with the devpath of the one that
366 static void reap_kids()
368 /* reap all dead children */
370 int pid = waitpid(-1, 0, WNOHANG);
371 if ((pid == -1) || (pid == 0))
377 /* just read everything from the pipe and clear the flag,
378 * the useful flags were set in the signal handler
380 static void user_sighandler()
384 int rc = read(pipefds[0],&sig,sizeof(sig));
393 int main(int argc, char *argv[])
395 int ssock, maxsockplus;
396 struct sockaddr_un saddr;
400 struct sigaction act;
403 init_logging("udevd");
404 dbg("version %s", UDEV_VERSION);
407 dbg("need to be root, exit");
411 /* setup signal handler pipe */
412 retval = pipe(pipefds);
414 dbg("error getting pipes: %s", strerror(errno));
418 retval = fcntl(pipefds[0], F_SETFL, O_NONBLOCK);
420 dbg("error fcntl on read pipe: %s", strerror(errno));
424 retval = fcntl(pipefds[1], F_SETFL, O_NONBLOCK);
426 dbg("error fcntl on write pipe: %s", strerror(errno));
430 /* set signal handlers */
431 act.sa_handler = sig_handler;
432 sigemptyset(&act.sa_mask);
433 act.sa_flags = SA_RESTART;
434 sigaction(SIGINT, &act, NULL);
435 sigaction(SIGTERM, &act, NULL);
436 sigaction(SIGALRM, &act, NULL);
437 sigaction(SIGCHLD, &act, NULL);
439 memset(&saddr, 0x00, sizeof(saddr));
440 saddr.sun_family = AF_LOCAL;
441 /* use abstract namespace for socket path */
442 strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
443 addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
445 ssock = socket(AF_LOCAL, SOCK_DGRAM, 0);
447 dbg("error getting socket, exit");
451 /* the bind takes care of ensuring only one copy running */
452 retval = bind(ssock, (struct sockaddr *) &saddr, addrlen);
454 dbg("bind failed, exit");
458 /* enable receiving of the sender credentials */
459 setsockopt(ssock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
462 FD_SET(ssock, &readfds);
463 FD_SET(pipefds[0], &readfds);
464 maxsockplus = ssock+1;
466 fd_set workreadfds = readfds;
467 retval = select(maxsockplus, &workreadfds, NULL, NULL, NULL);
471 dbg("error in select: %s", strerror(errno));
475 if (FD_ISSET(ssock, &workreadfds))
478 if (FD_ISSET(pipefds[0], &workreadfds))
481 if (children_waiting) {
482 children_waiting = 0;
492 /* this is tricky. exec_queue_manager() loops over exec_list, and
493 * calls running_with_devpath(), which loops over running_list. This gives
494 * O(N*M), which can get *nasty*. Clean up running_list before
495 * calling exec_queue_manager().
497 if (children_waiting) {
498 children_waiting = 0;
503 exec_queue_manager();