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