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 }