device.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   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
  31 static const UnitActiveState state_translation_table[_DEVICE_STATE_MAX] = {
  32         [DEVICE_DEAD] = UNIT_INACTIVE,
  33         [DEVICE_AVAILABLE] = UNIT_ACTIVE
  34 };
  35
  36 static const char* const state_string_table[_DEVICE_STATE_MAX] = {
  37         [DEVICE_DEAD] = "dead",
  38         [DEVICE_AVAILABLE] = "available"
  39 };
  40
  41 static void device_done(Unit *u) {
  42         Device *d = DEVICE(u);
  43
  44         assert(d);
  45         free(d->sysfs);
  46 }
  47
  48 static void device_set_state(Device *d, DeviceState state) {
  49         DeviceState old_state;
  50         assert(d);
  51
  52         if (state == d->state)
  53                 return;
  54
  55         old_state = d->state;
  56         d->state = state;
  57
  58         log_debug("%s changed %s → %s", unit_id(UNIT(d)), state_string_table[old_state], state_string_table[state]);
  59
  60         unit_notify(UNIT(d), state_translation_table[old_state], state_translation_table[state]);
  61 }
  62
  63 static int device_coldplug(Unit *u) {
  64         Device *d = DEVICE(u);
  65
  66         assert(d);
  67         assert(d->state == DEVICE_DEAD);
  68
  69         if (d->sysfs)
  70                 device_set_state(d, DEVICE_AVAILABLE);
  71
  72         return 0;
  73 }
  74
  75 static void device_dump(Unit *u, FILE *f, const char *prefix) {
  76         Device *d = DEVICE(u);
  77
  78         assert(d);
  79
  80         fprintf(f,
  81                 "%sDevice State: %s\n"
  82                 "%sSysfs Path: %s\n",
  83                 prefix, state_string_table[d->state],
  84                 prefix, strna(d->sysfs));
  85 }
  86
  87 static UnitActiveState device_active_state(Unit *u) {
  88         assert(u);
  89
  90         return state_translation_table[DEVICE(u)->state];
  91 }
  92
  93 static int device_add_escaped_name(Unit *u, const char *dn, bool make_id) {
  94         char *e;
  95         int r;
  96
  97         assert(u);
  98         assert(dn);
  99         assert(dn[0] == '/');
 100
 101         if (!(e = unit_name_escape_path(dn+1, ".device")))
 102                 return -ENOMEM;
 103
 104         r = unit_add_name(u, e);
 105
 106         if (r >= 0 && make_id)
 107                 unit_choose_id(u, e);
 108
 109         free(e);
 110
 111         if (r < 0 && r != -EEXIST)
 112                 return r;
 113
 114         return 0;
 115 }
 116
 117 static int device_find_escape_name(Manager *m, const char *dn, Unit **_u) {
 118         char *e;
 119         Unit *u;
 120
 121         assert(m);
 122         assert(dn);
 123         assert(dn[0] == '/');
 124         assert(_u);
 125
 126         if (!(e = unit_name_escape_path(dn+1, ".device")))
 127                 return -ENOMEM;
 128
 129         u = manager_get_unit(m, e);
 130         free(e);
 131
 132         if (u) {
 133                 *_u = u;
 134                 return 1;
 135         }
 136
 137         return 0;
 138 }
 139
 140 static bool devnode_is_api(const char *node) {
 141         unsigned i;
 142
 143         static const char * const table[] = {
 144                 "/dev/null",
 145                 "/dev/zero",
 146                 "/dev/urandom",
 147                 "/dev/random",
 148                 "/dev/port",
 149                 "/dev/oldmem",
 150                 "/dev/full",
 151                 "/dev/kmsg",
 152                 "/dev/mem"
 153         };
 154
 155         for (i = 0; i < ELEMENTSOF(table); i++)
 156                 if (streq(table[i], node))
 157                         return true;
 158
 159         return false;
 160 }
 161
 162 static int device_process_new_device(Manager *m, struct udev_device *dev, bool update_state) {
 163         const char *dn, *names, *wants, *sysfs, *expose, *model;
 164         Unit *u = NULL;
 165         int r;
 166         char *w, *state;
 167         size_t l;
 168         bool delete;
 169         struct udev_list_entry *item = NULL, *first = NULL;
 170
 171         assert(m);
 172
 173         if (!(sysfs = udev_device_get_syspath(dev)))
 174                 return -ENOMEM;
 175
 176         /* Check whether this entry is even relevant for us. */
 177         dn = udev_device_get_devnode(dev);
 178         expose = udev_device_get_property_value(dev, "SYSTEMD_EXPOSE");
 179         names = udev_device_get_property_value(dev, "SYSTEMD_NAMES");
 180         wants = udev_device_get_property_value(dev, "SYSTEMD_WANTS");
 181
 182         if (expose) {
 183                 int b;
 184
 185                 if ((b = parse_boolean(expose)) < 0) {
 186                         log_error("Failed to parse SYSTEMD_EXPOSE udev property for device %s: %s", sysfs, expose);
 187                         return 0;
 188                 }
 189
 190                 if (!b)
 191                         return 0;
 192         } else
 193                 if ((!dn || devnode_is_api(dn)) && !names && !wants)
 194                         return 0;
 195
 196         /* Ok, seems kinda interesting. Now, let's see if this one
 197          * already exists. */
 198
 199         if ((r = device_find_escape_name(m, sysfs, &u)) < 0)
 200                 return r;
 201
 202         if (r == 0 && dn)
 203                 if ((r = device_find_escape_name(m, dn, &u)) < 0)
 204                         return r;
 205
 206         if (r == 0) {
 207                 first = udev_device_get_devlinks_list_entry(dev);
 208                 udev_list_entry_foreach(item, first) {
 209                         if ((r = device_find_escape_name(m, udev_list_entry_get_name(item), &u)) < 0)
 210                                 return r;
 211
 212                         if (r > 0)
 213                                 break;
 214                 }
 215         }
 216
 217         /* FIXME: this needs proper merging */
 218
 219         assert((r > 0) == !!u);
 220
 221         /* If this is a different unit, then let's not merge things */
 222         if (u && DEVICE(u)->sysfs && !streq(DEVICE(u)->sysfs, sysfs))
 223                 u = NULL;
 224
 225         if (!u) {
 226                 delete = true;
 227
 228                 if (!(u = unit_new(m)))
 229                         return -ENOMEM;
 230
 231                 if ((r = device_add_escaped_name(u, sysfs, true)) < 0)
 232                         goto fail;
 233
 234                 if (!(DEVICE(u)->sysfs = strdup(sysfs))) {
 235                         r = -ENOMEM;
 236                         goto fail;
 237                 }
 238
 239                 unit_add_to_load_queue(u);
 240         } else
 241                 delete = false;
 242
 243         if (dn)
 244                 if ((r = device_add_escaped_name(u, dn, true)) < 0)
 245                         goto fail;
 246
 247         first = udev_device_get_devlinks_list_entry(dev);
 248         udev_list_entry_foreach(item, first)
 249                 if ((r = device_add_escaped_name(u, udev_list_entry_get_name(item), false)) < 0)
 250                         goto fail;
 251
 252         if ((model = udev_device_get_property_value(dev, "ID_MODEL_FROM_DATABASE")) ||
 253             (model = udev_device_get_property_value(dev, "ID_MODEL"))) {
 254                 if ((r = unit_set_description(u, model)) < 0)
 255                         goto fail;
 256         } else if (dn)
 257                 if ((r = unit_set_description(u, dn)) < 0)
 258                         goto fail;
 259
 260         /* We don't remove names that are gone. But that should be
 261          * fine and should probably be fixed only on a configuration
 262          * refresh. */
 263
 264         if (names) {
 265                 FOREACH_WORD(w, l, names, state) {
 266                         char *e;
 267
 268                         if (!(e = strndup(w, l))) {
 269                                 r = -ENOMEM;
 270                                 goto fail;
 271                         }
 272
 273                         r = unit_add_name(u, e);
 274                         free(e);
 275
 276                         if (r < 0 && r != -EEXIST)
 277                                 goto fail;
 278                 }
 279         }
 280
 281         if (wants) {
 282                 FOREACH_WORD(w, l, wants, state) {
 283                         char *e;
 284
 285                         if (!(e = strndup(w, l))) {
 286                                 r = -ENOMEM;
 287                                 goto fail;
 288                         }
 289
 290                         r = unit_add_dependency_by_name(u, UNIT_WANTS, e);
 291                         free(e);
 292
 293                         if (r < 0)
 294                                 goto fail;
 295                 }
 296         }
 297
 298         if (update_state) {
 299                 manager_dispatch_load_queue(u->meta.manager);
 300                 device_set_state(DEVICE(u), DEVICE_AVAILABLE);
 301         }
 302
 303         unit_add_to_dbus_queue(u);
 304
 305         return 0;
 306
 307 fail:
 308         if (delete && u)
 309                 unit_free(u);
 310         return r;
 311 }
 312
 313 static int device_process_path(Manager *m, const char *path, bool update_state) {
 314         int r;
 315         struct udev_device *dev;
 316
 317         assert(m);
 318         assert(path);
 319
 320         if (!(dev = udev_device_new_from_syspath(m->udev, path))) {
 321                 log_warning("Failed to get udev device object from udev for path %s.", path);
 322                 return -ENOMEM;
 323         }
 324
 325         r = device_process_new_device(m, dev, update_state);
 326         udev_device_unref(dev);
 327         return r;
 328 }
 329
 330 static int device_process_removed_device(Manager *m, struct udev_device *dev) {
 331         const char *sysfs;
 332         char *e;
 333         Unit *u;
 334         Device *d;
 335
 336         assert(m);
 337         assert(dev);
 338
 339         if (!(sysfs = udev_device_get_syspath(dev)))
 340                 return -ENOMEM;
 341
 342         assert(sysfs[0] == '/');
 343         if (!(e = unit_name_escape_path(sysfs+1, ".device")))
 344                 return -ENOMEM;
 345
 346         u = manager_get_unit(m, e);
 347         free(e);
 348
 349         if (!u)
 350                 return 0;
 351
 352         d = DEVICE(u);
 353         free(d->sysfs);
 354         d->sysfs = NULL;
 355
 356         device_set_state(d, DEVICE_DEAD);
 357         return 0;
 358 }
 359
 360 static void device_shutdown(Manager *m) {
 361         assert(m);
 362
 363         if (m->udev_monitor)
 364                 udev_monitor_unref(m->udev_monitor);
 365
 366         if (m->udev)
 367                 udev_unref(m->udev);
 368 }
 369
 370 static int device_enumerate(Manager *m) {
 371         struct epoll_event ev;
 372         int r;
 373         struct udev_enumerate *e = NULL;
 374         struct udev_list_entry *item = NULL, *first = NULL;
 375
 376         assert(m);
 377
 378         if (!(m->udev = udev_new()))
 379                 return -ENOMEM;
 380
 381         if (!(m->udev_monitor = udev_monitor_new_from_netlink(m->udev, "udev"))) {
 382                 r = -ENOMEM;
 383                 goto fail;
 384         }
 385
 386         if (udev_monitor_enable_receiving(m->udev_monitor) < 0) {
 387                 r = -EIO;
 388                 goto fail;
 389         }
 390
 391         m->udev_watch.type = WATCH_UDEV;
 392         m->udev_watch.fd = udev_monitor_get_fd(m->udev_monitor);
 393
 394         zero(ev);
 395         ev.events = EPOLLIN;
 396         ev.data.ptr = &m->udev_watch;
 397
 398         if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->udev_watch.fd, &ev) < 0)
 399                 return -errno;
 400
 401         if (!(e = udev_enumerate_new(m->udev))) {
 402                 r = -ENOMEM;
 403                 goto fail;
 404         }
 405
 406         if (udev_enumerate_scan_devices(e) < 0) {
 407                 r = -EIO;
 408                 goto fail;
 409         }
 410
 411         first = udev_enumerate_get_list_entry(e);
 412         udev_list_entry_foreach(item, first)
 413                 device_process_path(m, udev_list_entry_get_name(item), false);
 414
 415         udev_enumerate_unref(e);
 416         return 0;
 417
 418 fail:
 419         if (e)
 420                 udev_enumerate_unref(e);
 421
 422         device_shutdown(m);
 423         return r;
 424 }
 425
 426 void device_fd_event(Manager *m, int events) {
 427         struct udev_device *dev;
 428         int r;
 429         const char *action;
 430
 431         assert(m);
 432         assert(events == EPOLLIN);
 433
 434         if (!(dev = udev_monitor_receive_device(m->udev_monitor))) {
 435                 log_error("Failed to receive device.");
 436                 return;
 437         }
 438
 439         if (!(action = udev_device_get_action(dev))) {
 440                 log_error("Failed to get udev action string.");
 441                 goto fail;
 442         }
 443
 444         if (streq(action, "remove")) {
 445                 if ((r = device_process_removed_device(m, dev)) < 0) {
 446                         log_error("Failed to process udev device event: %s", strerror(-r));
 447                         goto fail;
 448                 }
 449         } else {
 450                 if ((r = device_process_new_device(m, dev, true)) < 0) {
 451                         log_error("Failed to process udev device event: %s", strerror(-r));
 452                         goto fail;
 453                 }
 454         }
 455
 456 fail:
 457         udev_device_unref(dev);
 458 }
 459
 460 const UnitVTable device_vtable = {
 461         .suffix = ".device",
 462
 463         .init = unit_load_fragment_and_dropin_optional,
 464         .done = device_done,
 465         .coldplug = device_coldplug,
 466
 467         .dump = device_dump,
 468
 469         .active_state = device_active_state,
 470
 471         .enumerate = device_enumerate,
 472         .shutdown = device_shutdown
 473 };