src/device.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <sys/epoll.h>
  24 #include <libudev.h>
  25
  26 #include "unit.h"
  27 #include "device.h"
  28 #include "strv.h"
  29 #include "log.h"
  30 #include "unit-name.h"
  31 #include "dbus-device.h"
  32
  33 static const UnitActiveState state_translation_table[_DEVICE_STATE_MAX] = {
  34         [DEVICE_DEAD] = UNIT_INACTIVE,
  35         [DEVICE_PLUGGED] = UNIT_ACTIVE
  36 };
  37
  38 static void device_unset_sysfs(Device *d) {
  39         Device *first;
  40
  41         assert(d);
  42
  43         if (!d->sysfs)
  44                 return;
  45
  46         /* Remove this unit from the chain of devices which share the
  47          * same sysfs path. */
  48         first = hashmap_get(d->meta.manager->devices_by_sysfs, d->sysfs);
  49         LIST_REMOVE(Device, same_sysfs, first, d);
  50
  51         if (first)
  52                 hashmap_remove_and_replace(d->meta.manager->devices_by_sysfs, d->sysfs, first->sysfs, first);
  53         else
  54                 hashmap_remove(d->meta.manager->devices_by_sysfs, d->sysfs);
  55
  56         free(d->sysfs);
  57         d->sysfs = NULL;
  58 }
  59
  60 static void device_init(Unit *u) {
  61         Device *d = DEVICE(u);
  62
  63         assert(d);
  64         assert(d->meta.load_state == UNIT_STUB);
  65
  66         /* In contrast to all other unit types we timeout jobs waiting
  67          * for devices by default. This is because they otherwise wait
  68          * indefinetely for plugged in devices, something which cannot
  69          * happen for the other units since their operations time out
  70          * anyway. */
  71         d->meta.job_timeout = DEFAULT_TIMEOUT_USEC;
  72
  73         /* We enable recursive stopping by default for all
  74         devices. This enables the user to use Requires= to make a
  75         service go a way when a device goes away, and Wants=
  76         otherwise. */
  77         d->meta.recursive_stop = true;
  78 }
  79
  80 static void device_done(Unit *u) {
  81         Device *d = DEVICE(u);
  82
  83         assert(d);
  84
  85         device_unset_sysfs(d);
  86 }
  87
  88 static void device_set_state(Device *d, DeviceState state) {
  89         DeviceState old_state;
  90         assert(d);
  91
  92         old_state = d->state;
  93         d->state = state;
  94
  95         if (state != old_state)
  96                 log_debug("%s changed %s -> %s",
  97                           d->meta.id,
  98                           device_state_to_string(old_state),
  99                           device_state_to_string(state));
 100
 101         unit_notify(UNIT(d), state_translation_table[old_state], state_translation_table[state]);
 102 }
 103
 104 static int device_coldplug(Unit *u) {
 105         Device *d = DEVICE(u);
 106
 107         assert(d);
 108         assert(d->state == DEVICE_DEAD);
 109
 110         if (d->sysfs)
 111                 device_set_state(d, DEVICE_PLUGGED);
 112
 113         return 0;
 114 }
 115
 116 static void device_dump(Unit *u, FILE *f, const char *prefix) {
 117         Device *d = DEVICE(u);
 118
 119         assert(d);
 120
 121         fprintf(f,
 122                 "%sDevice State: %s\n"
 123                 "%sSysfs Path: %s\n",
 124                 prefix, device_state_to_string(d->state),
 125                 prefix, strna(d->sysfs));
 126 }
 127
 128 static UnitActiveState device_active_state(Unit *u) {
 129         assert(u);
 130
 131         return state_translation_table[DEVICE(u)->state];
 132 }
 133
 134 static const char *device_sub_state_to_string(Unit *u) {
 135         assert(u);
 136
 137         return device_state_to_string(DEVICE(u)->state);
 138 }
 139
 140 static int device_add_escaped_name(Unit *u, const char *dn) {
 141         char *e;
 142         int r;
 143
 144         assert(u);
 145         assert(dn);
 146         assert(dn[0] == '/');
 147
 148         if (!(e = unit_name_from_path(dn, ".device")))
 149                 return -ENOMEM;
 150
 151         r = unit_add_name(u, e);
 152         free(e);
 153
 154         if (r < 0 && r != -EEXIST)
 155                 return r;
 156
 157         return 0;
 158 }
 159
 160 static int device_find_escape_name(Manager *m, const char *dn, Unit **_u) {
 161         char *e;
 162         Unit *u;
 163
 164         assert(m);
 165         assert(dn);
 166         assert(dn[0] == '/');
 167         assert(_u);
 168
 169         if (!(e = unit_name_from_path(dn, ".device")))
 170                 return -ENOMEM;
 171
 172         u = manager_get_unit(m, e);
 173         free(e);
 174
 175         if (u) {
 176                 *_u = u;
 177                 return 1;
 178         }
 179
 180         return 0;
 181 }
 182
 183 static int device_update_unit(Manager *m, struct udev_device *dev, const char *path, bool main) {
 184         const char *sysfs, *model;
 185         Unit *u = NULL;
 186         int r;
 187         bool delete;
 188
 189         assert(m);
 190
 191         if (!(sysfs = udev_device_get_syspath(dev)))
 192                 return -ENOMEM;
 193
 194         if ((r = device_find_escape_name(m, path, &u)) < 0)
 195                 return r;
 196
 197         if (u && DEVICE(u)->sysfs && !path_equal(DEVICE(u)->sysfs, sysfs))
 198                 return -EEXIST;
 199
 200         if (!u) {
 201                 delete = true;
 202
 203                 if (!(u = unit_new(m)))
 204                         return -ENOMEM;
 205
 206                 if ((r = device_add_escaped_name(u, path)) < 0)
 207                         goto fail;
 208
 209                 unit_add_to_load_queue(u);
 210         } else
 211                 delete = false;
 212
 213         /* If this was created via some dependency and has not
 214          * actually been seen yet ->sysfs will not be
 215          * initialized. Hence initialize it if necessary. */
 216
 217         if (!DEVICE(u)->sysfs) {
 218                 Device *first;
 219
 220                 if (!(DEVICE(u)->sysfs = strdup(sysfs))) {
 221                         r = -ENOMEM;
 222                         goto fail;
 223                 }
 224
 225                 if (!m->devices_by_sysfs)
 226                         if (!(m->devices_by_sysfs = hashmap_new(string_hash_func, string_compare_func))) {
 227                                 r = -ENOMEM;
 228                                 goto fail;
 229                         }
 230
 231                 first = hashmap_get(m->devices_by_sysfs, sysfs);
 232                 LIST_PREPEND(Device, same_sysfs, first, DEVICE(u));
 233
 234                 if ((r = hashmap_replace(m->devices_by_sysfs, DEVICE(u)->sysfs, first)) < 0)
 235                         goto fail;
 236         }
 237
 238         if ((model = udev_device_get_property_value(dev, "ID_MODEL_FROM_DATABASE")) ||
 239             (model = udev_device_get_property_value(dev, "ID_MODEL"))) {
 240                 if ((r = unit_set_description(u, model)) < 0)
 241                         goto fail;
 242         } else
 243                 if ((r = unit_set_description(u, path)) < 0)
 244                         goto fail;
 245
 246         if (main) {
 247                 /* The additional systemd udev properties we only
 248                  * interpret for the main object */
 249                 const char *wants, *alias;
 250
 251                 if ((alias = udev_device_get_property_value(dev, "SYSTEMD_ALIAS"))) {
 252                         if (!is_path(alias))
 253                                 log_warning("SYSTEMD_ALIAS for %s is not a path, ignoring: %s", sysfs, alias);
 254                         else {
 255                                 if ((r = device_add_escaped_name(u, alias)) < 0)
 256                                         goto fail;
 257                         }
 258                 }
 259
 260                 if ((wants = udev_device_get_property_value(dev, "SYSTEMD_WANTS"))) {
 261                         char *state, *w;
 262                         size_t l;
 263
 264                         FOREACH_WORD_QUOTED(w, l, wants, state) {
 265                                 char *e;
 266
 267                                 if (!(e = strndup(w, l))) {
 268                                         r = -ENOMEM;
 269                                         goto fail;
 270                                 }
 271
 272                                 r = unit_add_dependency_by_name(u, UNIT_WANTS, e, NULL, true);
 273                                 free(e);
 274
 275                                 if (r < 0)
 276                                         goto fail;
 277                         }
 278                 }
 279         }
 280
 281         unit_add_to_dbus_queue(u);
 282         return 0;
 283
 284 fail:
 285         log_warning("Failed to load device unit: %s", strerror(-r));
 286
 287         if (delete && u)
 288                 unit_free(u);
 289
 290         return r;
 291 }
 292
 293 static int device_process_new_device(Manager *m, struct udev_device *dev, bool update_state) {
 294         const char *sysfs, *dn;
 295         struct udev_list_entry *item = NULL, *first = NULL;
 296
 297         assert(m);
 298
 299         if (!(sysfs = udev_device_get_syspath(dev)))
 300                 return -ENOMEM;
 301
 302         /* Add the main unit named after the sysfs path */
 303         device_update_unit(m, dev, sysfs, true);
 304
 305         /* Add an additional unit for the device node */
 306         if ((dn = udev_device_get_devnode(dev)))
 307                 device_update_unit(m, dev, dn, false);
 308
 309         /* Add additional units for all symlinks */
 310         first = udev_device_get_devlinks_list_entry(dev);
 311         udev_list_entry_foreach(item, first) {
 312                 const char *p;
 313                 struct stat st;
 314
 315                 /* Don't bother with the /dev/block links */
 316                 p = udev_list_entry_get_name(item);
 317
 318                 if (path_startswith(p, "/dev/block/") ||
 319                     path_startswith(p, "/dev/char/"))
 320                         continue;
 321
 322                 /* Verify that the symlink in the FS actually belongs
 323                  * to this device. This is useful to deal with
 324                  * conflicting devices, e.g. when two disks want the
 325                  * same /dev/disk/by-label/xxx link because they have
 326                  * the same label. We want to make sure that the same
 327                  * device that won the symlink wins in systemd, so we
 328                  * check the device node major/minor*/
 329                 if (stat(p, &st) >= 0)
 330                         if ((!S_ISBLK(st.st_mode) && !S_ISCHR(st.st_mode)) ||
 331                             st.st_rdev != udev_device_get_devnum(dev))
 332                                 continue;
 333
 334                 device_update_unit(m, dev, p, false);
 335         }
 336
 337         if (update_state) {
 338                 Device *d, *l;
 339
 340                 manager_dispatch_load_queue(m);
 341
 342                 l = hashmap_get(m->devices_by_sysfs, sysfs);
 343                 LIST_FOREACH(same_sysfs, d, l)
 344                         device_set_state(d, DEVICE_PLUGGED);
 345         }
 346
 347         return 0;
 348 }
 349
 350 static int device_process_path(Manager *m, const char *path, bool update_state) {
 351         int r;
 352         struct udev_device *dev;
 353
 354         assert(m);
 355         assert(path);
 356
 357         if (!(dev = udev_device_new_from_syspath(m->udev, path))) {
 358                 log_warning("Failed to get udev device object from udev for path %s.", path);
 359                 return -ENOMEM;
 360         }
 361
 362         r = device_process_new_device(m, dev, update_state);
 363         udev_device_unref(dev);
 364         return r;
 365 }
 366
 367 static int device_process_removed_device(Manager *m, struct udev_device *dev) {
 368         const char *sysfs;
 369         Device *d;
 370
 371         assert(m);
 372         assert(dev);
 373
 374         if (!(sysfs = udev_device_get_syspath(dev)))
 375                 return -ENOMEM;
 376
 377         /* Remove all units of this sysfs path */
 378         while ((d = hashmap_get(m->devices_by_sysfs, sysfs))) {
 379                 device_unset_sysfs(d);
 380                 device_set_state(d, DEVICE_DEAD);
 381         }
 382
 383         return 0;
 384 }
 385
 386 static Unit *device_following(Unit *u) {
 387         Device *d = DEVICE(u);
 388         Device *other, *first = NULL;
 389
 390         assert(d);
 391
 392         if (startswith(u->meta.id, "sys-"))
 393                 return NULL;
 394
 395         /* Make everybody follow the unit that's named after the sysfs path */
 396         for (other = d->same_sysfs_next; other; other = other->same_sysfs_next)
 397                 if (startswith(other->meta.id, "sys-"))
 398                         return UNIT(other);
 399
 400         for (other = d->same_sysfs_prev; other; other = other->same_sysfs_prev) {
 401                 if (startswith(other->meta.id, "sys-"))
 402                         return UNIT(other);
 403
 404                 first = other;
 405         }
 406
 407         return UNIT(first);
 408 }
 409
 410 static void device_shutdown(Manager *m) {
 411         assert(m);
 412
 413         if (m->udev_monitor) {
 414                 udev_monitor_unref(m->udev_monitor);
 415                 m->udev_monitor = NULL;
 416         }
 417
 418         if (m->udev) {
 419                 udev_unref(m->udev);
 420                 m->udev = NULL;
 421         }
 422
 423         hashmap_free(m->devices_by_sysfs);
 424         m->devices_by_sysfs = NULL;
 425 }
 426
 427 static int device_enumerate(Manager *m) {
 428         struct epoll_event ev;
 429         int r;
 430         struct udev_enumerate *e = NULL;
 431         struct udev_list_entry *item = NULL, *first = NULL;
 432
 433         assert(m);
 434
 435         if (!m->udev) {
 436                 if (!(m->udev = udev_new()))
 437                         return -ENOMEM;
 438
 439                 if (!(m->udev_monitor = udev_monitor_new_from_netlink(m->udev, "udev"))) {
 440                         r = -ENOMEM;
 441                         goto fail;
 442                 }
 443
 444                 if (udev_monitor_filter_add_match_tag(m->udev_monitor, "systemd") < 0) {
 445                         r = -ENOMEM;
 446                         goto fail;
 447                 }
 448
 449                 if (udev_monitor_enable_receiving(m->udev_monitor) < 0) {
 450                         r = -EIO;
 451                         goto fail;
 452                 }
 453
 454                 m->udev_watch.type = WATCH_UDEV;
 455                 m->udev_watch.fd = udev_monitor_get_fd(m->udev_monitor);
 456
 457                 zero(ev);
 458                 ev.events = EPOLLIN;
 459                 ev.data.ptr = &m->udev_watch;
 460
 461                 if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->udev_watch.fd, &ev) < 0)
 462                         return -errno;
 463         }
 464
 465         if (!(e = udev_enumerate_new(m->udev))) {
 466                 r = -ENOMEM;
 467                 goto fail;
 468         }
 469         if (udev_enumerate_add_match_tag(e, "systemd") < 0) {
 470                 r = -EIO;
 471                 goto fail;
 472         }
 473
 474         if (udev_enumerate_scan_devices(e) < 0) {
 475                 r = -EIO;
 476                 goto fail;
 477         }
 478
 479         first = udev_enumerate_get_list_entry(e);
 480         udev_list_entry_foreach(item, first)
 481                 device_process_path(m, udev_list_entry_get_name(item), false);
 482
 483         udev_enumerate_unref(e);
 484         return 0;
 485
 486 fail:
 487         if (e)
 488                 udev_enumerate_unref(e);
 489
 490         device_shutdown(m);
 491         return r;
 492 }
 493
 494 void device_fd_event(Manager *m, int events) {
 495         struct udev_device *dev;
 496         int r;
 497         const char *action;
 498
 499         assert(m);
 500         assert(events == EPOLLIN);
 501
 502         if (!(dev = udev_monitor_receive_device(m->udev_monitor))) {
 503                 log_error("Failed to receive device.");
 504                 return;
 505         }
 506
 507         if (!(action = udev_device_get_action(dev))) {
 508                 log_error("Failed to get udev action string.");
 509                 goto fail;
 510         }
 511
 512         if (streq(action, "remove")) {
 513                 if ((r = device_process_removed_device(m, dev)) < 0) {
 514                         log_error("Failed to process udev device event: %s", strerror(-r));
 515                         goto fail;
 516                 }
 517         } else {
 518                 if ((r = device_process_new_device(m, dev, true)) < 0) {
 519                         log_error("Failed to process udev device event: %s", strerror(-r));
 520                         goto fail;
 521                 }
 522         }
 523
 524 fail:
 525         udev_device_unref(dev);
 526 }
 527
 528 static const char* const device_state_table[_DEVICE_STATE_MAX] = {
 529         [DEVICE_DEAD] = "dead",
 530         [DEVICE_PLUGGED] = "plugged"
 531 };
 532
 533 DEFINE_STRING_TABLE_LOOKUP(device_state, DeviceState);
 534
 535 const UnitVTable device_vtable = {
 536         .suffix = ".device",
 537
 538         .no_requires = true,
 539         .no_instances = true,
 540         .no_snapshots = true,
 541         .no_isolate = true,
 542
 543         .init = device_init,
 544
 545         .load = unit_load_fragment_and_dropin_optional,
 546         .done = device_done,
 547         .coldplug = device_coldplug,
 548
 549         .dump = device_dump,
 550
 551         .active_state = device_active_state,
 552         .sub_state_to_string = device_sub_state_to_string,
 553
 554         .bus_interface = "org.freedesktop.systemd1.Device",
 555         .bus_message_handler = bus_device_message_handler,
 556         .bus_invalidating_properties =  bus_device_invalidating_properties,
 557
 558         .following = device_following,
 559
 560         .enumerate = device_enumerate,
 561         .shutdown = device_shutdown
 562 };