src/path.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 <sys/inotify.h>
  23 #include <sys/epoll.h>
  24 #include <sys/ioctl.h>
  25 #include <errno.h>
  26 #include <unistd.h>
  27
  28 #include "unit.h"
  29 #include "unit-name.h"
  30 #include "path.h"
  31 #include "dbus-path.h"
  32 #include "special.h"
  33 #include "bus-errors.h"
  34
  35 static const UnitActiveState state_translation_table[_PATH_STATE_MAX] = {
  36         [PATH_DEAD] = UNIT_INACTIVE,
  37         [PATH_WAITING] = UNIT_ACTIVE,
  38         [PATH_RUNNING] = UNIT_ACTIVE,
  39         [PATH_FAILED] = UNIT_FAILED
  40 };
  41
  42 static void path_unwatch_one(Path *p, PathSpec *s) {
  43
  44         if (s->inotify_fd < 0)
  45                 return;
  46
  47         unit_unwatch_fd(UNIT(p), &s->watch);
  48
  49         close_nointr_nofail(s->inotify_fd);
  50         s->inotify_fd = -1;
  51 }
  52
  53 static void path_done(Unit *u) {
  54         Path *p = PATH(u);
  55         PathSpec *s;
  56
  57         assert(p);
  58
  59         while ((s = p->specs)) {
  60                 path_unwatch_one(p, s);
  61                 LIST_REMOVE(PathSpec, spec, p->specs, s);
  62                 free(s->path);
  63                 free(s);
  64         }
  65 }
  66
  67 int path_add_one_mount_link(Path *p, Mount *m) {
  68         PathSpec *s;
  69         int r;
  70
  71         assert(p);
  72         assert(m);
  73
  74         if (p->meta.load_state != UNIT_LOADED ||
  75             m->meta.load_state != UNIT_LOADED)
  76                 return 0;
  77
  78         LIST_FOREACH(spec, s, p->specs) {
  79
  80                 if (!path_startswith(s->path, m->where))
  81                         continue;
  82
  83                 if ((r = unit_add_two_dependencies(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, UNIT(m), true)) < 0)
  84                         return r;
  85         }
  86
  87         return 0;
  88 }
  89
  90 static int path_add_mount_links(Path *p) {
  91         Meta *other;
  92         int r;
  93
  94         assert(p);
  95
  96         LIST_FOREACH(units_per_type, other, p->meta.manager->units_per_type[UNIT_MOUNT])
  97                 if ((r = path_add_one_mount_link(p, (Mount*) other)) < 0)
  98                         return r;
  99
 100         return 0;
 101 }
 102
 103 static int path_verify(Path *p) {
 104         assert(p);
 105
 106         if (p->meta.load_state != UNIT_LOADED)
 107                 return 0;
 108
 109         if (!p->specs) {
 110                 log_error("%s lacks path setting. Refusing.", p->meta.id);
 111                 return -EINVAL;
 112         }
 113
 114         return 0;
 115 }
 116
 117 static int path_add_default_dependencies(Path *p) {
 118         int r;
 119
 120         assert(p);
 121
 122         if (p->meta.manager->running_as == MANAGER_SYSTEM) {
 123                 if ((r = unit_add_dependency_by_name(UNIT(p), UNIT_BEFORE, SPECIAL_BASIC_TARGET, NULL, true)) < 0)
 124                         return r;
 125
 126                 if ((r = unit_add_two_dependencies_by_name(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, NULL, true)) < 0)
 127                         return r;
 128         }
 129
 130         return unit_add_two_dependencies_by_name(UNIT(p), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true);
 131 }
 132
 133 static int path_load(Unit *u) {
 134         Path *p = PATH(u);
 135         int r;
 136
 137         assert(u);
 138         assert(u->meta.load_state == UNIT_STUB);
 139
 140         if ((r = unit_load_fragment_and_dropin(u)) < 0)
 141                 return r;
 142
 143         if (u->meta.load_state == UNIT_LOADED) {
 144
 145                 if (!p->unit)
 146                         if ((r = unit_load_related_unit(u, ".service", &p->unit)))
 147                                 return r;
 148
 149                 if ((r = unit_add_dependency(u, UNIT_BEFORE, p->unit, true)) < 0)
 150                         return r;
 151
 152                 if ((r = path_add_mount_links(p)) < 0)
 153                         return r;
 154
 155                 if (p->meta.default_dependencies)
 156                         if ((r = path_add_default_dependencies(p)) < 0)
 157                                 return r;
 158         }
 159
 160         return path_verify(p);
 161 }
 162
 163 static void path_dump(Unit *u, FILE *f, const char *prefix) {
 164         Path *p = PATH(u);
 165         PathSpec *s;
 166
 167         assert(p);
 168         assert(f);
 169
 170         fprintf(f,
 171                 "%sPath State: %s\n"
 172                 "%sUnit: %s\n",
 173                 prefix, path_state_to_string(p->state),
 174                 prefix, p->unit->meta.id);
 175
 176         LIST_FOREACH(spec, s, p->specs)
 177                 fprintf(f,
 178                         "%s%s: %s\n",
 179                         prefix,
 180                         path_type_to_string(s->type),
 181                         s->path);
 182 }
 183
 184 static int path_watch_one(Path *p, PathSpec *s) {
 185         static const int flags_table[_PATH_TYPE_MAX] = {
 186                 [PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
 187                 [PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
 188                 [PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO
 189         };
 190
 191         bool exists = false;
 192         char *k, *slash;
 193         int r;
 194
 195         assert(p);
 196         assert(s);
 197
 198         path_unwatch_one(p, s);
 199
 200         if (!(k = strdup(s->path)))
 201                 return -ENOMEM;
 202
 203         if ((s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC)) < 0) {
 204                 r = -errno;
 205                 goto fail;
 206         }
 207
 208         if (unit_watch_fd(UNIT(p), s->inotify_fd, EPOLLIN, &s->watch) < 0) {
 209                 r = -errno;
 210                 goto fail;
 211         }
 212
 213         if ((s->primary_wd = inotify_add_watch(s->inotify_fd, k, flags_table[s->type])) >= 0)
 214                 exists = true;
 215
 216         do {
 217                 int flags;
 218
 219                 /* This assumes the path was passed through path_kill_slashes()! */
 220                 if (!(slash = strrchr(k, '/')))
 221                         break;
 222
 223                 /* Trim the path at the last slash. Keep the slash if it's the root dir. */
 224                 slash[slash == k] = 0;
 225
 226                 flags = IN_MOVE_SELF;
 227                 if (!exists)
 228                         flags |= IN_DELETE_SELF | IN_ATTRIB | IN_CREATE | IN_MOVED_TO;
 229
 230                 if (inotify_add_watch(s->inotify_fd, k, flags) >= 0)
 231                         exists = true;
 232         } while (slash != k);
 233
 234         return 0;
 235
 236 fail:
 237         free(k);
 238
 239         path_unwatch_one(p, s);
 240         return r;
 241 }
 242
 243 static void path_unwatch(Path *p) {
 244         PathSpec *s;
 245
 246         assert(p);
 247
 248         LIST_FOREACH(spec, s, p->specs)
 249                 path_unwatch_one(p, s);
 250 }
 251
 252 static int path_watch(Path *p) {
 253         int r;
 254         PathSpec *s;
 255
 256         assert(p);
 257
 258         LIST_FOREACH(spec, s, p->specs)
 259                 if ((r = path_watch_one(p, s)) < 0)
 260                         return r;
 261
 262         return 0;
 263 }
 264
 265 static void path_set_state(Path *p, PathState state) {
 266         PathState old_state;
 267         assert(p);
 268
 269         old_state = p->state;
 270         p->state = state;
 271
 272         if (state != PATH_WAITING &&
 273             (state != PATH_RUNNING || p->inotify_triggered))
 274                 path_unwatch(p);
 275
 276         if (state != old_state)
 277                 log_debug("%s changed %s -> %s",
 278                           p->meta.id,
 279                           path_state_to_string(old_state),
 280                           path_state_to_string(state));
 281
 282         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state], true);
 283 }
 284
 285 static void path_enter_waiting(Path *p, bool initial, bool recheck, bool skip_watch);
 286
 287 static int path_coldplug(Unit *u) {
 288         Path *p = PATH(u);
 289
 290         assert(p);
 291         assert(p->state == PATH_DEAD);
 292
 293         if (p->deserialized_state != p->state) {
 294
 295                 if (p->deserialized_state == PATH_WAITING ||
 296                     p->deserialized_state == PATH_RUNNING)
 297                         path_enter_waiting(p, true, true, false);
 298                 else
 299                         path_set_state(p, p->deserialized_state);
 300         }
 301
 302         return 0;
 303 }
 304
 305 static void path_enter_dead(Path *p, bool success) {
 306         assert(p);
 307
 308         if (!success)
 309                 p->failure = true;
 310
 311         path_set_state(p, p->failure ? PATH_FAILED : PATH_DEAD);
 312 }
 313
 314 static void path_enter_running(Path *p) {
 315         int r;
 316         DBusError error;
 317
 318         assert(p);
 319         dbus_error_init(&error);
 320
 321         /* Don't start job if we are supposed to go down */
 322         if (p->meta.job && p->meta.job->type == JOB_STOP)
 323                 return;
 324
 325         if ((r = manager_add_job(p->meta.manager, JOB_START, p->unit, JOB_REPLACE, true, &error, NULL)) < 0)
 326                 goto fail;
 327
 328         p->inotify_triggered = false;
 329
 330         if ((r = path_watch(p)) < 0)
 331                 goto fail;
 332
 333         path_set_state(p, PATH_RUNNING);
 334         return;
 335
 336 fail:
 337         log_warning("%s failed to queue unit startup job: %s", p->meta.id, bus_error(&error, r));
 338         path_enter_dead(p, false);
 339
 340         dbus_error_free(&error);
 341 }
 342
 343
 344 static void path_enter_waiting(Path *p, bool initial, bool recheck, bool skip_watch) {
 345         PathSpec *s;
 346         int r;
 347         bool good = false;
 348
 349         if (!recheck)
 350                 goto waiting;
 351
 352         LIST_FOREACH(spec, s, p->specs) {
 353
 354                 switch (s->type) {
 355
 356                 case PATH_EXISTS:
 357                         good = access(s->path, F_OK) >= 0;
 358                         break;
 359
 360                 case PATH_DIRECTORY_NOT_EMPTY: {
 361                         int k;
 362
 363                         k = dir_is_empty(s->path);
 364                         good = !(k == -ENOENT || k > 0);
 365                         break;
 366                 }
 367
 368                 case PATH_CHANGED: {
 369                         bool b;
 370
 371                         b = access(s->path, F_OK) >= 0;
 372                         good = !initial && b != s->previous_exists;
 373                         s->previous_exists = b;
 374                         break;
 375                 }
 376
 377                 default:
 378                         ;
 379                 }
 380
 381                 if (good)
 382                         break;
 383         }
 384
 385         if (good) {
 386                 log_debug("%s got triggered.", p->meta.id);
 387                 path_enter_running(p);
 388                 return;
 389         }
 390
 391 waiting:
 392         if (!skip_watch) {
 393                 if ((r = path_watch(p)) < 0)
 394                         goto fail;
 395
 396                 /* Hmm, so now we have created inotify watches, but the file
 397                  * might have appeared/been removed by now, so we must
 398                  * recheck */
 399                 path_enter_waiting(p, false, true, true);
 400                 return;
 401         }
 402
 403         path_set_state(p, PATH_WAITING);
 404         return;
 405
 406 fail:
 407         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 408         path_enter_dead(p, false);
 409 }
 410
 411 static int path_start(Unit *u) {
 412         Path *p = PATH(u);
 413
 414         assert(p);
 415         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 416
 417         if (p->unit->meta.load_state != UNIT_LOADED)
 418                 return -ENOENT;
 419
 420         p->failure = false;
 421         path_enter_waiting(p, true, true, false);
 422
 423         return 0;
 424 }
 425
 426 static int path_stop(Unit *u) {
 427         Path *p = PATH(u);
 428
 429         assert(p);
 430         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 431
 432         path_enter_dead(p, true);
 433         return 0;
 434 }
 435
 436 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 437         Path *p = PATH(u);
 438
 439         assert(u);
 440         assert(f);
 441         assert(fds);
 442
 443         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 444
 445         return 0;
 446 }
 447
 448 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 449         Path *p = PATH(u);
 450
 451         assert(u);
 452         assert(key);
 453         assert(value);
 454         assert(fds);
 455
 456         if (streq(key, "state")) {
 457                 PathState state;
 458
 459                 if ((state = path_state_from_string(value)) < 0)
 460                         log_debug("Failed to parse state value %s", value);
 461                 else
 462                         p->deserialized_state = state;
 463         } else
 464                 log_debug("Unknown serialization key '%s'", key);
 465
 466         return 0;
 467 }
 468
 469 static UnitActiveState path_active_state(Unit *u) {
 470         assert(u);
 471
 472         return state_translation_table[PATH(u)->state];
 473 }
 474
 475 static const char *path_sub_state_to_string(Unit *u) {
 476         assert(u);
 477
 478         return path_state_to_string(PATH(u)->state);
 479 }
 480
 481 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 482         Path *p = PATH(u);
 483         int l;
 484         ssize_t k;
 485         uint8_t *buf = NULL;
 486         struct inotify_event *e;
 487         PathSpec *s;
 488         bool changed;
 489
 490         assert(p);
 491         assert(fd >= 0);
 492
 493         if (p->state != PATH_WAITING &&
 494             p->state != PATH_RUNNING)
 495                 return;
 496
 497         /* log_debug("inotify wakeup on %s.", u->meta.id); */
 498
 499         if (events != EPOLLIN) {
 500                 log_error("Got Invalid poll event on inotify.");
 501                 goto fail;
 502         }
 503
 504         LIST_FOREACH(spec, s, p->specs)
 505                 if (s->inotify_fd == fd)
 506                         break;
 507
 508         if (!s) {
 509                 log_error("Got event on unknown fd.");
 510                 goto fail;
 511         }
 512
 513         if (ioctl(fd, FIONREAD, &l) < 0) {
 514                 log_error("FIONREAD failed: %s", strerror(errno));
 515                 goto fail;
 516         }
 517
 518         if (!(buf = malloc(l))) {
 519                 log_error("Failed to allocate buffer: %s", strerror(-ENOMEM));
 520                 goto fail;
 521         }
 522
 523         if ((k = read(fd, buf, l)) < 0) {
 524                 log_error("Failed to read inotify event: %s", strerror(-errno));
 525                 goto fail;
 526         }
 527
 528         /* If we are already running, then remember that one event was
 529          * dispatched so that we restart the service only if something
 530          * actually changed on disk */
 531         p->inotify_triggered = true;
 532
 533         e = (struct inotify_event*) buf;
 534
 535         changed = false;
 536         while (k > 0) {
 537                 size_t step;
 538
 539                 if (s->type == PATH_CHANGED && s->primary_wd == e->wd)
 540                         changed = true;
 541
 542                 step = sizeof(struct inotify_event) + e->len;
 543                 assert(step <= (size_t) k);
 544
 545                 e = (struct inotify_event*) ((uint8_t*) e + step);
 546                 k -= step;
 547         }
 548
 549         if (changed)
 550                 path_enter_running(p);
 551         else
 552                 path_enter_waiting(p, false, true, false);
 553
 554         free(buf);
 555
 556         return;
 557
 558 fail:
 559         free(buf);
 560         path_enter_dead(p, false);
 561 }
 562
 563 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 564         char *n;
 565         int r;
 566         Iterator i;
 567
 568         if (u->meta.type == UNIT_PATH)
 569                 return;
 570
 571         SET_FOREACH(n, u->meta.names, i) {
 572                 char *k;
 573                 Unit *t;
 574                 Path *p;
 575
 576                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 577                         r = -ENOMEM;
 578                         goto fail;
 579                 }
 580
 581                 t = manager_get_unit(u->meta.manager, k);
 582                 free(k);
 583
 584                 if (!t)
 585                         continue;
 586
 587                 if (t->meta.load_state != UNIT_LOADED)
 588                         continue;
 589
 590                 p = PATH(t);
 591
 592                 if (p->unit != u)
 593                         continue;
 594
 595                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 596                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 597
 598                         /* Hmm, so inotify was triggered since the
 599                          * last activation, so I guess we need to
 600                          * recheck what is going on. */
 601                         path_enter_waiting(p, false, p->inotify_triggered, false);
 602                 }
 603         }
 604
 605         return;
 606
 607 fail:
 608         log_error("Failed find path unit: %s", strerror(-r));
 609 }
 610
 611 static void path_reset_failed(Unit *u) {
 612         Path *p = PATH(u);
 613
 614         assert(p);
 615
 616         if (p->state == PATH_FAILED)
 617                 path_set_state(p, PATH_DEAD);
 618
 619         p->failure = false;
 620 }
 621
 622 static const char* const path_state_table[_PATH_STATE_MAX] = {
 623         [PATH_DEAD] = "dead",
 624         [PATH_WAITING] = "waiting",
 625         [PATH_RUNNING] = "running",
 626         [PATH_FAILED] = "failed"
 627 };
 628
 629 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 630
 631 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 632         [PATH_EXISTS] = "PathExists",
 633         [PATH_CHANGED] = "PathChanged",
 634         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 635 };
 636
 637 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 638
 639 const UnitVTable path_vtable = {
 640         .suffix = ".path",
 641
 642         .done = path_done,
 643         .load = path_load,
 644
 645         .coldplug = path_coldplug,
 646
 647         .dump = path_dump,
 648
 649         .start = path_start,
 650         .stop = path_stop,
 651
 652         .serialize = path_serialize,
 653         .deserialize_item = path_deserialize_item,
 654
 655         .active_state = path_active_state,
 656         .sub_state_to_string = path_sub_state_to_string,
 657
 658         .fd_event = path_fd_event,
 659
 660         .reset_failed = path_reset_failed,
 661
 662         .bus_interface = "org.freedesktop.systemd1.Path",
 663         .bus_message_handler = bus_path_message_handler
 664 };