chiark / gitweb /
3ce8c8b07dbe56003f80324bb84aec66cfc4d980
[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/wait.h>
25 #include <signal.h>
26 #include <unistd.h>
27 #include <errno.h>
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <time.h>
32 #include <sys/types.h>
33 #include <sys/socket.h>
34 #include <sys/un.h>
35
36 #include "list.h"
37 #include "udev.h"
38 #include "udev_version.h"
39 #include "udevd.h"
40 #include "logging.h"
41
42
43 unsigned char logname[42];
44 static pthread_mutex_t  msg_lock;
45 static pthread_mutex_t  msg_active_lock;
46 static pthread_cond_t msg_active;
47 static pthread_mutex_t  exec_lock;
48 static pthread_mutex_t  exec_active_lock;
49 static pthread_cond_t exec_active;
50 static pthread_mutex_t  running_lock;
51 static pthread_attr_t thr_attr;
52 static int expected_seqnum = 0;
53
54 LIST_HEAD(msg_list);
55 LIST_HEAD(exec_list);
56 LIST_HEAD(running_list);
57
58
59 static void msg_dump_queue(void)
60 {
61         struct hotplug_msg *msg;
62
63         list_for_each_entry(msg, &msg_list, list)
64                 dbg("sequence %d in queue", msg->seqnum);
65 }
66
67 static void msg_dump(struct hotplug_msg *msg)
68 {
69         dbg("sequence %d, '%s', '%s', '%s'",
70             msg->seqnum, msg->action, msg->devpath, msg->subsystem);
71 }
72
73 static struct hotplug_msg *msg_create(void)
74 {
75         struct hotplug_msg *new_msg;
76
77         new_msg = malloc(sizeof(struct hotplug_msg));
78         if (new_msg == NULL) {
79                 dbg("error malloc");
80                 return NULL;
81         }
82         return new_msg;
83 }
84
85 static void msg_delete(struct hotplug_msg *msg)
86 {
87         if (msg != NULL)
88                 free(msg);
89 }
90
91 /* orders the message in the queue by sequence number */
92 static void msg_queue_insert(struct hotplug_msg *msg)
93 {
94         struct hotplug_msg *loop_msg;
95
96         /* sort message by sequence number into list*/
97         list_for_each_entry(loop_msg, &msg_list, list)
98                 if (loop_msg->seqnum > msg->seqnum)
99                         break;
100         list_add_tail(&msg->list, &loop_msg->list);
101         dbg("queued message seq %d", msg->seqnum);
102
103         /* store timestamp of queuing */
104         msg->queue_time = time(NULL);
105
106         /* signal queue activity to manager */
107         pthread_mutex_lock(&msg_active_lock);
108         pthread_cond_signal(&msg_active);
109         pthread_mutex_unlock(&msg_active_lock);
110
111         return ;
112 }
113
114 /* forks event and removes event from run queue when finished */
115 static void *run_threads(void * parm)
116 {
117         pid_t pid;
118         struct hotplug_msg *msg;
119
120         msg = parm;
121         setenv("ACTION", msg->action, 1);
122         setenv("DEVPATH", msg->devpath, 1);
123
124         pid = fork();
125         switch (pid) {
126         case 0:
127                 /* child */
128                 execl(UDEV_BIN, "udev", msg->subsystem, NULL);
129                 dbg("exec of child failed");
130                 exit(1);
131                 break;
132         case -1:
133                 dbg("fork of child failed");
134                 goto exit;
135         default:
136                 /* wait for exit of child */
137                 dbg("==> exec seq %d [%d] working at '%s'",
138                     msg->seqnum, pid, msg->devpath);
139                 wait(NULL);
140                 dbg("<== exec seq %d came back", msg->seqnum);
141         }
142
143 exit:
144         /* remove event from run list */
145         pthread_mutex_lock(&running_lock);
146         list_del_init(&msg->list);
147         pthread_mutex_unlock(&running_lock);
148
149         msg_delete(msg);
150
151         /* signal queue activity to exec manager */
152         pthread_mutex_lock(&exec_active_lock);
153         pthread_cond_signal(&exec_active);
154         pthread_mutex_unlock(&exec_active_lock);
155
156         pthread_exit(0);
157 }
158
159 /* returns already running task with devpath */
160 static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
161 {
162         struct hotplug_msg *loop_msg;
163         struct hotplug_msg *tmp_msg;
164
165         list_for_each_entry_safe(loop_msg, tmp_msg, &running_list, list)
166                 if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
167                         return loop_msg;
168         return NULL;
169 }
170
171 /* queue management executes the events and delays events for the same devpath */
172 static void *exec_queue_manager(void * parm)
173 {
174         struct hotplug_msg *loop_msg;
175         struct hotplug_msg *tmp_msg;
176         struct hotplug_msg *msg;
177         pthread_t run_tid;
178
179         while (1) {
180                 pthread_mutex_lock(&exec_lock);
181                 list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
182                         msg = running_with_devpath(loop_msg);
183                         if (msg == NULL) {
184                                 /* move event to run list */
185                                 pthread_mutex_lock(&running_lock);
186                                 list_move_tail(&loop_msg->list, &running_list);
187                                 pthread_mutex_unlock(&running_lock);
188
189                                 pthread_create(&run_tid, &thr_attr, run_threads, (void *) loop_msg);
190
191                                 dbg("moved seq %d to running list", loop_msg->seqnum);
192                         } else {
193                                 dbg("delay seq %d, cause seq %d already working on '%s'",
194                                     loop_msg->seqnum, msg->seqnum, msg->devpath);
195                         }
196                 }
197                 pthread_mutex_unlock(&exec_lock);
198
199                 /* wait for activation, new events or childs coming back */
200                 pthread_mutex_lock(&exec_active_lock);
201                 pthread_cond_wait(&exec_active, &exec_active_lock);
202                 pthread_mutex_unlock(&exec_active_lock);
203         }
204 }
205
206 static void exec_queue_activate(void)
207 {
208         pthread_mutex_lock(&exec_active_lock);
209         pthread_cond_signal(&exec_active);
210         pthread_mutex_unlock(&exec_active_lock);
211 }
212
213 /* move message from incoming to exec queue */
214 static void msg_move_exec(struct list_head *head)
215 {
216         list_move_tail(head, &exec_list);
217         exec_queue_activate();
218 }
219
220 /* queue management thread handles the timeouts and dispatches the events */
221 static void *msg_queue_manager(void * parm)
222 {
223         struct hotplug_msg *loop_msg;
224         struct hotplug_msg *tmp_msg;
225         time_t msg_age = 0;
226         struct timespec tv;
227
228         while (1) {
229                 dbg("msg queue manager, next expected is %d", expected_seqnum);
230                 pthread_mutex_lock(&msg_lock);
231                 pthread_mutex_lock(&exec_lock);
232 recheck:
233                 list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
234                         /* move event with expected sequence to the exec list */
235                         if (loop_msg->seqnum == expected_seqnum) {
236                                 msg_move_exec(&loop_msg->list);
237                                 expected_seqnum++;
238                                 dbg("moved seq %d to exec, next expected is %d",
239                                     loop_msg->seqnum, expected_seqnum);
240                                 continue;
241                         }
242
243                         /* move event with expired timeout to the exec list */
244                         msg_age = time(NULL) - loop_msg->queue_time;
245                         if (msg_age > EVENT_TIMEOUT_SEC-1) {
246                                 msg_move_exec(&loop_msg->list);
247                                 expected_seqnum = loop_msg->seqnum+1;
248                                 dbg("moved seq %d to exec, reset next expected to %d",
249                                     loop_msg->seqnum, expected_seqnum);
250                                 goto recheck;
251                         } else {
252                                 break;
253                         }
254                 }
255
256                 msg_dump_queue();
257                 pthread_mutex_unlock(&exec_lock);
258                 pthread_mutex_unlock(&msg_lock);
259
260                 /* wait until queue gets active or next message timeout expires */
261                 pthread_mutex_lock(&msg_active_lock);
262
263                 if (list_empty(&msg_list) == 0) {
264                         tv.tv_sec = time(NULL) + EVENT_TIMEOUT_SEC - msg_age;
265                         tv.tv_nsec = 0;
266                         dbg("next event expires in %li seconds",
267                             EVENT_TIMEOUT_SEC - msg_age);
268                         pthread_cond_timedwait(&msg_active, &msg_active_lock, &tv);
269                 } else {
270                         pthread_cond_wait(&msg_active, &msg_active_lock);
271                 }
272                 pthread_mutex_unlock(&msg_active_lock);
273         }
274 }
275
276 /* every connect creates a thread which gets the msg, queues it and exits */
277 static void *client_threads(void * parm)
278 {
279         int sock;
280         struct hotplug_msg *msg;
281         int retval;
282
283         sock = (int) parm;
284
285         msg = msg_create();
286         if (msg == NULL) {
287                 dbg("unable to store message");
288                 goto exit;
289         }
290
291         retval = recv(sock, msg, sizeof(struct hotplug_msg), 0);
292         if (retval <  0) {
293                 dbg("unable to receive message");
294                 goto exit;
295         }
296
297         if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
298                 dbg("message magic '%s' doesn't match, ignore it", msg->magic);
299                 msg_delete(msg);
300                 goto exit;
301         }
302
303         /* if no seqnum is given, we move straight to exec queue */
304         if (msg->seqnum == 0) {
305                 pthread_mutex_lock(&exec_lock);
306                 list_add(&msg->list, &exec_list);
307                 exec_queue_activate();
308                 pthread_mutex_unlock(&exec_lock);
309         } else {
310                 pthread_mutex_lock(&msg_lock);
311                 msg_queue_insert(msg);
312                 pthread_mutex_unlock(&msg_lock);
313         }
314
315 exit:
316         close(sock);
317         pthread_exit(0);
318 }
319
320 static void sig_handler(int signum)
321 {
322         switch (signum) {
323                 case SIGINT:
324                 case SIGTERM:
325                         exit(20 + signum);
326                         break;
327                 default:
328                         dbg("unhandled signal");
329         }
330 }
331
332 int main(int argc, char *argv[])
333 {
334         int ssock;
335         int csock;
336         struct sockaddr_un saddr;
337         struct sockaddr_un caddr;
338         socklen_t addrlen;
339         socklen_t clen;
340         pthread_t cli_tid;
341         pthread_t mgr_msg_tid;
342         pthread_t mgr_exec_tid;
343         int retval;
344
345         init_logging("udevd");
346
347         signal(SIGINT, sig_handler);
348         signal(SIGTERM, sig_handler);
349
350         memset(&saddr, 0x00, sizeof(saddr));
351         saddr.sun_family = AF_LOCAL;
352         /* use abstract namespace for socket path */
353         strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
354         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
355
356         ssock = socket(AF_LOCAL, SOCK_STREAM, 0);
357         if (ssock == -1) {
358                 dbg("error getting socket");
359                 exit(1);
360         }
361
362         retval = bind(ssock, &saddr, addrlen);
363         if (retval < 0) {
364                 dbg("bind failed\n");
365                 goto exit;
366         }
367
368         retval = listen(ssock, SOMAXCONN);
369         if (retval < 0) {
370                 dbg("listen failed\n");
371                 goto exit;
372         }
373
374         pthread_mutex_init(&msg_lock, NULL);
375         pthread_mutex_init(&msg_active_lock, NULL);
376         pthread_mutex_init(&exec_lock, NULL);
377         pthread_mutex_init(&exec_active_lock, NULL);
378         pthread_mutex_init(&running_lock, NULL);
379
380         /* set default attributes for created threads */
381         pthread_attr_init(&thr_attr);
382         pthread_attr_setdetachstate(&thr_attr, PTHREAD_CREATE_DETACHED);
383         pthread_attr_setstacksize(&thr_attr, 16 * 1024);
384
385         /* init queue management */
386         pthread_create(&mgr_msg_tid, &thr_attr, msg_queue_manager, NULL);
387         pthread_create(&mgr_exec_tid, &thr_attr, exec_queue_manager, NULL);
388
389         clen = sizeof(caddr);
390         /* main loop */
391         while (1) {
392                 csock = accept(ssock, &caddr, &clen);
393                 if (csock < 0) {
394                         dbg("client accept failed\n");
395                         continue;
396                 }
397                 pthread_create(&cli_tid, &thr_attr, client_threads, (void *) csock);
398         }
399 exit:
400         close(ssock);
401         exit(1);
402 }