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 }