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 strcpy(action, "ACTION=");
143 strfieldcat(action, msg->action);
144 strcpy(devpath, "DEVPATH=");
145 strfieldcat(devpath, msg->devpath);
151 execle(UDEV_BIN, "udev", msg->subsystem, NULL, env);
152 dbg("exec of child failed");
156 dbg("fork of child failed");
157 run_queue_delete(msg);
158 /* note: we never managed to run, so we had no impact on
159 * running_with_devpath(), so don't bother setting run_exec_q
163 /* get SIGCHLD in main loop */
164 dbg("==> exec seq %d [%d] working at '%s'", msg->seqnum, pid, msg->devpath);
169 /* returns already running task with devpath */
170 static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
172 struct hotplug_msg *loop_msg;
173 list_for_each_entry(loop_msg, &running_list, list)
174 if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
179 /* exec queue management routine executes the events and delays events for the same devpath */
180 static void exec_queue_manager()
182 struct hotplug_msg *loop_msg;
183 struct hotplug_msg *tmp_msg;
184 struct hotplug_msg *msg;
186 list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
187 msg = running_with_devpath(loop_msg);
189 /* move event to run list */
190 list_move_tail(&loop_msg->list, &running_list);
192 dbg("moved seq %d to running list", loop_msg->seqnum);
194 dbg("delay seq %d, cause seq %d already working on '%s'",
195 loop_msg->seqnum, msg->seqnum, msg->devpath);
200 static void msg_move_exec(struct hotplug_msg *msg)
202 list_move_tail(&msg->list, &exec_list);
204 expected_seqnum = msg->seqnum+1;
205 dbg("moved seq %d to exec, next expected is %d",
206 msg->seqnum, expected_seqnum);
209 /* msg queue management routine handles the timeouts and dispatches the events */
210 static void msg_queue_manager()
212 struct hotplug_msg *loop_msg;
213 struct hotplug_msg *tmp_msg;
217 dbg("msg queue manager, next expected is %d", expected_seqnum);
219 list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
220 /* move event with expected sequence to the exec list */
221 if (loop_msg->seqnum == expected_seqnum) {
222 msg_move_exec(loop_msg);
226 /* move event with expired timeout to the exec list */
228 msg_age = info.uptime - loop_msg->queue_time;
229 dbg("seq %d is %li seconds old", loop_msg->seqnum, msg_age);
230 if (msg_age > EVENT_TIMEOUT_SEC-1) {
231 msg_move_exec(loop_msg);
240 /* set timeout for remaining queued events */
241 if (list_empty(&msg_list) == 0) {
242 struct itimerval itv = {{0, 0}, {EVENT_TIMEOUT_SEC - msg_age, 0}};
243 dbg("next event expires in %li seconds", EVENT_TIMEOUT_SEC - msg_age);
244 setitimer(ITIMER_REAL, &itv, 0);
248 /* receive the msg, do some basic sanity checks, and queue it */
249 static void handle_msg(int sock)
251 struct hotplug_msg *msg;
254 struct cmsghdr *cmsg;
257 char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
261 dbg("unable to store message");
266 iov.iov_len = sizeof(struct hotplug_msg);
268 memset(&smsg, 0x00, sizeof(struct msghdr));
271 smsg.msg_control = cred_msg;
272 smsg.msg_controllen = sizeof(cred_msg);
274 retval = recvmsg(sock, &smsg, 0);
277 dbg("unable to receive message");
280 cmsg = CMSG_FIRSTHDR(&smsg);
281 cred = (struct ucred *) CMSG_DATA(cmsg);
283 if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
284 dbg("no sender credentials received, message ignored");
288 if (cred->uid != 0) {
289 dbg("sender uid=%i, message ignored", cred->uid);
293 if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
294 dbg("message magic '%s' doesn't match, ignore it", msg->magic);
298 /* if no seqnum is given, we move straight to exec queue */
299 if (msg->seqnum == -1) {
300 list_add(&msg->list, &exec_list);
303 msg_queue_insert(msg);
312 static void sig_handler(int signum)
321 /* set flag, then write to pipe if needed */
326 /* set flag, then write to pipe if needed */
327 children_waiting = 1;
331 dbg("unhandled signal");
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 %d 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_kids()
370 /* reap all dead children */
372 int pid = waitpid(-1, 0, WNOHANG);
373 if ((pid == -1) || (pid == 0))
379 /* just read everything from the pipe and clear the flag,
380 * the useful flags were set in the signal handler
382 static void user_sighandler()
386 int rc = read(pipefds[0],&sig,sizeof(sig));
395 int main(int argc, char *argv[])
397 int ssock, maxsockplus;
398 struct sockaddr_un saddr;
402 struct sigaction act;
405 init_logging("udevd");
406 dbg("version %s", UDEV_VERSION);
409 dbg("need to be root, exit");
413 /* setup signal handler pipe */
414 retval = pipe(pipefds);
416 dbg("error getting pipes: %s", strerror(errno));
420 retval = fcntl(pipefds[0], F_SETFL, O_NONBLOCK);
422 dbg("error fcntl on read pipe: %s", strerror(errno));
426 retval = fcntl(pipefds[1], F_SETFL, O_NONBLOCK);
428 dbg("error fcntl on write pipe: %s", strerror(errno));
432 /* set signal handlers */
433 act.sa_handler = sig_handler;
434 sigemptyset(&act.sa_mask);
435 act.sa_flags = SA_RESTART;
436 sigaction(SIGINT, &act, NULL);
437 sigaction(SIGTERM, &act, NULL);
438 sigaction(SIGALRM, &act, NULL);
439 sigaction(SIGCHLD, &act, NULL);
441 memset(&saddr, 0x00, sizeof(saddr));
442 saddr.sun_family = AF_LOCAL;
443 /* use abstract namespace for socket path */
444 strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
445 addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
447 ssock = socket(AF_LOCAL, SOCK_DGRAM, 0);
449 dbg("error getting socket, exit");
453 /* the bind takes care of ensuring only one copy running */
454 retval = bind(ssock, (struct sockaddr *) &saddr, addrlen);
456 dbg("bind failed, exit");
460 /* enable receiving of the sender credentials */
461 setsockopt(ssock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
464 FD_SET(ssock, &readfds);
465 FD_SET(pipefds[0], &readfds);
466 maxsockplus = ssock+1;
468 fd_set workreadfds = readfds;
469 retval = select(maxsockplus, &workreadfds, NULL, NULL, NULL);
473 dbg("error in select: %s", strerror(errno));
477 if (FD_ISSET(ssock, &workreadfds))
480 if (FD_ISSET(pipefds[0], &workreadfds))
483 if (children_waiting) {
484 children_waiting = 0;
494 /* this is tricky. exec_queue_manager() loops over exec_list, and
495 * calls running_with_devpath(), which loops over running_list. This gives
496 * O(N*M), which can get *nasty*. Clean up running_list before
497 * calling exec_queue_manager().
499 if (children_waiting) {
500 children_waiting = 0;
505 exec_queue_manager();