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[PATCH] make udevsend binary even smaller
[elogind.git] / udevd.c
1 /*
2  * udevd.c - hotplug event serializer
3  *
4  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
5  *
6  *
7  *      This program is free software; you can redistribute it and/or modify it
8  *      under the terms of the GNU General Public License as published by the
9  *      Free Software Foundation version 2 of the License.
10  *
11  *      This program is distributed in the hope that it will be useful, but
12  *      WITHOUT ANY WARRANTY; without even the implied warranty of
13  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  *      General Public License for more details.
15  *
16  *      You should have received a copy of the GNU General Public License along
17  *      with this program; if not, write to the Free Software Foundation, Inc.,
18  *      675 Mass Ave, Cambridge, MA 02139, USA.
19  *
20  */
21
22 #include <pthread.h>
23 #include <stddef.h>
24 #include <sys/types.h>
25 #include <sys/wait.h>
26 #include <signal.h>
27 #include <unistd.h>
28 #include <errno.h>
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <time.h>
33 #include <fcntl.h>
34 #include <sys/types.h>
35 #include <sys/socket.h>
36 #include <sys/un.h>
37
38 #include "list.h"
39 #include "udev.h"
40 #include "udev_version.h"
41 #include "udevd.h"
42 #include "logging.h"
43
44
45 unsigned char logname[42];
46 static pthread_mutex_t  msg_lock;
47 static pthread_mutex_t  msg_active_lock;
48 static pthread_cond_t msg_active;
49 static pthread_mutex_t  exec_lock;
50 static pthread_mutex_t  exec_active_lock;
51 static pthread_cond_t exec_active;
52 static pthread_mutex_t  running_lock;
53 static pthread_attr_t thr_attr;
54 static int expected_seqnum = 0;
55
56 LIST_HEAD(msg_list);
57 LIST_HEAD(exec_list);
58 LIST_HEAD(running_list);
59
60
61 static void msg_dump_queue(void)
62 {
63         struct hotplug_msg *msg;
64
65         list_for_each_entry(msg, &msg_list, list)
66                 dbg("sequence %d in queue", msg->seqnum);
67 }
68
69 static void msg_dump(struct hotplug_msg *msg)
70 {
71         dbg("sequence %d, '%s', '%s', '%s'",
72             msg->seqnum, msg->action, msg->devpath, msg->subsystem);
73 }
74
75 static struct hotplug_msg *msg_create(void)
76 {
77         struct hotplug_msg *new_msg;
78
79         new_msg = malloc(sizeof(struct hotplug_msg));
80         if (new_msg == NULL) {
81                 dbg("error malloc");
82                 return NULL;
83         }
84         return new_msg;
85 }
86
87 static void msg_delete(struct hotplug_msg *msg)
88 {
89         if (msg != NULL)
90                 free(msg);
91 }
92
93 /* orders the message in the queue by sequence number */
94 static void msg_queue_insert(struct hotplug_msg *msg)
95 {
96         struct hotplug_msg *loop_msg;
97
98         /* sort message by sequence number into list*/
99         list_for_each_entry(loop_msg, &msg_list, list)
100                 if (loop_msg->seqnum > msg->seqnum)
101                         break;
102         list_add_tail(&msg->list, &loop_msg->list);
103         dbg("queued message seq %d", msg->seqnum);
104
105         /* store timestamp of queuing */
106         msg->queue_time = time(NULL);
107
108         /* signal queue activity to manager */
109         pthread_mutex_lock(&msg_active_lock);
110         pthread_cond_signal(&msg_active);
111         pthread_mutex_unlock(&msg_active_lock);
112
113         return ;
114 }
115
116 /* forks event and removes event from run queue when finished */
117 static void *run_threads(void * parm)
118 {
119         pid_t pid;
120         struct hotplug_msg *msg;
121
122         msg = parm;
123         setenv("ACTION", msg->action, 1);
124         setenv("DEVPATH", msg->devpath, 1);
125
126         pid = fork();
127         switch (pid) {
128         case 0:
129                 /* child */
130                 execl(UDEV_BIN, "udev", msg->subsystem, NULL);
131                 dbg("exec of child failed");
132                 exit(1);
133                 break;
134         case -1:
135                 dbg("fork of child failed");
136                 goto exit;
137         default:
138                 /* wait for exit of child */
139                 dbg("==> exec seq %d [%d] working at '%s'",
140                     msg->seqnum, pid, msg->devpath);
141                 wait(NULL);
142                 dbg("<== exec seq %d came back", msg->seqnum);
143         }
144
145 exit:
146         /* remove event from run list */
147         pthread_mutex_lock(&running_lock);
148         list_del_init(&msg->list);
149         pthread_mutex_unlock(&running_lock);
150
151         msg_delete(msg);
152
153         /* signal queue activity to exec manager */
154         pthread_mutex_lock(&exec_active_lock);
155         pthread_cond_signal(&exec_active);
156         pthread_mutex_unlock(&exec_active_lock);
157
158         pthread_exit(0);
159 }
160
161 /* returns already running task with devpath */
162 static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
163 {
164         struct hotplug_msg *loop_msg;
165         struct hotplug_msg *tmp_msg;
166
167         list_for_each_entry_safe(loop_msg, tmp_msg, &running_list, list)
168                 if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
169                         return loop_msg;
170         return NULL;
171 }
172
173 /* queue management executes the events and delays events for the same devpath */
174 static void *exec_queue_manager(void * parm)
175 {
176         struct hotplug_msg *loop_msg;
177         struct hotplug_msg *tmp_msg;
178         struct hotplug_msg *msg;
179         pthread_t run_tid;
180
181         while (1) {
182                 pthread_mutex_lock(&exec_lock);
183                 list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
184                         msg = running_with_devpath(loop_msg);
185                         if (msg == NULL) {
186                                 /* move event to run list */
187                                 pthread_mutex_lock(&running_lock);
188                                 list_move_tail(&loop_msg->list, &running_list);
189                                 pthread_mutex_unlock(&running_lock);
190
191                                 pthread_create(&run_tid, &thr_attr, run_threads, (void *) loop_msg);
192
193                                 dbg("moved seq %d to running list", loop_msg->seqnum);
194                         } else {
195                                 dbg("delay seq %d, cause seq %d already working on '%s'",
196                                     loop_msg->seqnum, msg->seqnum, msg->devpath);
197                         }
198                 }
199                 pthread_mutex_unlock(&exec_lock);
200
201                 /* wait for activation, new events or childs coming back */
202                 pthread_mutex_lock(&exec_active_lock);
203                 pthread_cond_wait(&exec_active, &exec_active_lock);
204                 pthread_mutex_unlock(&exec_active_lock);
205         }
206 }
207
208 /* move message from incoming to exec queue */
209 static void msg_move_exec(struct list_head *head)
210 {
211         list_move_tail(head, &exec_list);
212         /* signal queue activity to manager */
213         pthread_mutex_lock(&exec_active_lock);
214         pthread_cond_signal(&exec_active);
215         pthread_mutex_unlock(&exec_active_lock);
216 }
217
218 /* queue management thread handles the timeouts and dispatches the events */
219 static void *msg_queue_manager(void * parm)
220 {
221         struct hotplug_msg *loop_msg;
222         struct hotplug_msg *tmp_msg;
223         time_t msg_age = 0;
224         struct timespec tv;
225
226         while (1) {
227                 dbg("msg queue manager, next expected is %d", expected_seqnum);
228                 pthread_mutex_lock(&msg_lock);
229                 pthread_mutex_lock(&exec_lock);
230 recheck:
231                 list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
232                         /* move event with expected sequence to the exec list */
233                         if (loop_msg->seqnum == expected_seqnum) {
234                                 msg_move_exec(&loop_msg->list);
235                                 expected_seqnum++;
236                                 dbg("moved seq %d to exec, next expected is %d",
237                                     loop_msg->seqnum, expected_seqnum);
238                                 continue;
239                         }
240
241                         /* move event with expired timeout to the exec list */
242                         msg_age = time(NULL) - loop_msg->queue_time;
243                         if (msg_age > EVENT_TIMEOUT_SEC-1) {
244                                 msg_move_exec(&loop_msg->list);
245                                 expected_seqnum = loop_msg->seqnum+1;
246                                 dbg("moved seq %d to exec, reset next expected to %d",
247                                     loop_msg->seqnum, expected_seqnum);
248                                 goto recheck;
249                         } else {
250                                 break;
251                         }
252                 }
253
254                 msg_dump_queue();
255                 pthread_mutex_unlock(&exec_lock);
256                 pthread_mutex_unlock(&msg_lock);
257
258                 /* wait until queue gets active or next message timeout expires */
259                 pthread_mutex_lock(&msg_active_lock);
260
261                 if (list_empty(&msg_list) == 0) {
262                         tv.tv_sec = time(NULL) + EVENT_TIMEOUT_SEC - msg_age;
263                         tv.tv_nsec = 0;
264                         dbg("next event expires in %li seconds",
265                             EVENT_TIMEOUT_SEC - msg_age);
266                         pthread_cond_timedwait(&msg_active, &msg_active_lock, &tv);
267                 } else {
268                         pthread_cond_wait(&msg_active, &msg_active_lock);
269                 }
270                 pthread_mutex_unlock(&msg_active_lock);
271         }
272 }
273
274 /* every connect creates a thread which gets the msg, queues it and exits */
275 static void *client_threads(void * parm)
276 {
277         int sock;
278         struct hotplug_msg *msg;
279         int retval;
280
281         sock = (int) parm;
282
283         msg = msg_create();
284         if (msg == NULL) {
285                 dbg("unable to store message");
286                 goto exit;
287         }
288
289         retval = recv(sock, msg, sizeof(struct hotplug_msg), 0);
290         if (retval <  0) {
291                 dbg("unable to receive message");
292                 goto exit;
293         }
294
295         if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
296                 dbg("message magic '%s' doesn't match, ignore it", msg->magic);
297                 msg_delete(msg);
298                 goto exit;
299         }
300
301         pthread_mutex_lock(&msg_lock);
302         msg_queue_insert(msg);
303         pthread_mutex_unlock(&msg_lock);
304
305 exit:
306         close(sock);
307         pthread_exit(0);
308 }
309
310 static void sig_handler(int signum)
311 {
312         switch (signum) {
313                 case SIGINT:
314                 case SIGTERM:
315                         unlink(UDEVD_LOCK);
316                         unlink(UDEVD_SOCK);
317                         exit(20 + signum);
318                         break;
319                 default:
320                         dbg("unhandled signal");
321         }
322 }
323
324 static int one_and_only(void)
325 {
326         char string[50];
327         int lock_file;
328
329         lock_file = open(UDEVD_LOCK, O_RDWR | O_CREAT, 0x640);
330         if (lock_file < 0)
331                 return -1;
332
333         /* see if we can lock */
334         if (lockf(lock_file, F_TLOCK, 0) < 0) {
335                 dbg("file is already locked, exit");
336                 close(lock_file);
337                 return -1;
338         }
339
340         snprintf(string, sizeof(string), "%d\n", getpid());
341         write(lock_file, string, strlen(string));
342
343         return 0;
344 }
345
346 int main(int argc, char *argv[])
347 {
348         int ssock;
349         int csock;
350         struct sockaddr_un saddr;
351         struct sockaddr_un caddr;
352         socklen_t clen;
353         pthread_t cli_tid;
354         pthread_t mgr_msg_tid;
355         pthread_t mgr_exec_tid;
356         int retval;
357
358         init_logging("udevd");
359
360         /* only let one version of the daemon run at any one time */
361         if (one_and_only() != 0)
362                 exit(0);
363
364         signal(SIGINT, sig_handler);
365         signal(SIGTERM, sig_handler);
366
367         memset(&saddr, 0x00, sizeof(saddr));
368         saddr.sun_family = AF_LOCAL;
369         strcpy(saddr.sun_path, UDEVD_SOCK);
370
371         unlink(UDEVD_SOCK);
372         ssock = socket(AF_LOCAL, SOCK_STREAM, 0);
373         if (ssock == -1) {
374                 dbg("error getting socket");
375                 exit(1);
376         }
377
378         retval = bind(ssock, &saddr, sizeof(saddr));
379         if (retval < 0) {
380                 dbg("bind failed\n");
381                 goto exit;
382         }
383
384         retval = listen(ssock, SOMAXCONN);
385         if (retval < 0) {
386                 dbg("listen failed\n");
387                 goto exit;
388         }
389
390         pthread_mutex_init(&msg_lock, NULL);
391         pthread_mutex_init(&msg_active_lock, NULL);
392         pthread_mutex_init(&exec_lock, NULL);
393         pthread_mutex_init(&exec_active_lock, NULL);
394         pthread_mutex_init(&running_lock, NULL);
395
396         /* set default attributes for created threads */
397         pthread_attr_init(&thr_attr);
398         pthread_attr_setdetachstate(&thr_attr, PTHREAD_CREATE_DETACHED);
399         pthread_attr_setstacksize(&thr_attr, 16 * 1024);
400
401         /* init queue management */
402         pthread_create(&mgr_msg_tid, &thr_attr, msg_queue_manager, NULL);
403         pthread_create(&mgr_exec_tid, &thr_attr, exec_queue_manager, NULL);
404
405         clen = sizeof(caddr);
406         /* main loop */
407         while (1) {
408                 csock = accept(ssock, &caddr, &clen);
409                 if (csock < 0) {
410                         dbg("client accept failed\n");
411                         continue;
412                 }
413                 pthread_create(&cli_tid, &thr_attr, client_threads, (void *) csock);
414         }
415 exit:
416         close(ssock);
417         unlink(UDEVD_SOCK);
418         exit(1);
419 }