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 int path_spec_watch(PathSpec *s, Unit *u) {
  43
  44         static const int flags_table[_PATH_TYPE_MAX] = {
  45                 [PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
  46                 [PATH_EXISTS_GLOB] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
  47                 [PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
  48                 [PATH_MODIFIED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO|IN_MODIFY,
  49                 [PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO
  50         };
  51
  52         bool exists = false;
  53         char *k, *slash;
  54         int r;
  55
  56         assert(u);
  57         assert(s);
  58
  59         path_spec_unwatch(s, u);
  60
  61         if (!(k = strdup(s->path)))
  62                 return -ENOMEM;
  63
  64         if ((s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC)) < 0) {
  65                 r = -errno;
  66                 goto fail;
  67         }
  68
  69         if (unit_watch_fd(u, s->inotify_fd, EPOLLIN, &s->watch) < 0) {
  70                 r = -errno;
  71                 goto fail;
  72         }
  73
  74         if ((s->primary_wd = inotify_add_watch(s->inotify_fd, k, flags_table[s->type])) >= 0)
  75                 exists = true;
  76
  77         do {
  78                 int flags;
  79
  80                 /* This assumes the path was passed through path_kill_slashes()! */
  81                 if (!(slash = strrchr(k, '/')))
  82                         break;
  83
  84                 /* Trim the path at the last slash. Keep the slash if it's the root dir. */
  85                 slash[slash == k] = 0;
  86
  87                 flags = IN_MOVE_SELF;
  88                 if (!exists)
  89                         flags |= IN_DELETE_SELF | IN_ATTRIB | IN_CREATE | IN_MOVED_TO;
  90
  91                 if (inotify_add_watch(s->inotify_fd, k, flags) >= 0)
  92                         exists = true;
  93         } while (slash != k);
  94
  95         return 0;
  96
  97 fail:
  98         free(k);
  99
 100         path_spec_unwatch(s, u);
 101         return r;
 102 }
 103
 104 void path_spec_unwatch(PathSpec *s, Unit *u) {
 105
 106         if (s->inotify_fd < 0)
 107                 return;
 108
 109         unit_unwatch_fd(u, &s->watch);
 110
 111         close_nointr_nofail(s->inotify_fd);
 112         s->inotify_fd = -1;
 113 }
 114
 115 int path_spec_fd_event(PathSpec *s, uint32_t events) {
 116         uint8_t *buf = NULL;
 117         struct inotify_event *e;
 118         ssize_t k;
 119         int l;
 120         int r = 0;
 121
 122         if (events != EPOLLIN) {
 123                 log_error("Got Invalid poll event on inotify.");
 124                 r = -EINVAL;
 125                 goto out;
 126         }
 127
 128         if (ioctl(s->inotify_fd, FIONREAD, &l) < 0) {
 129                 log_error("FIONREAD failed: %m");
 130                 r = -errno;
 131                 goto out;
 132         }
 133
 134         assert(l > 0);
 135
 136         if (!(buf = malloc(l))) {
 137                 log_error("Failed to allocate buffer: %m");
 138                 r = -errno;
 139                 goto out;
 140         }
 141
 142         if ((k = read(s->inotify_fd, buf, l)) < 0) {
 143                 log_error("Failed to read inotify event: %m");
 144                 r = -errno;
 145                 goto out;
 146         }
 147
 148         e = (struct inotify_event*) buf;
 149
 150         while (k > 0) {
 151                 size_t step;
 152
 153                 if ((s->type == PATH_CHANGED || s->type == PATH_MODIFIED) &&
 154                     s->primary_wd == e->wd)
 155                         r = 1;
 156
 157                 step = sizeof(struct inotify_event) + e->len;
 158                 assert(step <= (size_t) k);
 159
 160                 e = (struct inotify_event*) ((uint8_t*) e + step);
 161                 k -= step;
 162         }
 163 out:
 164         free(buf);
 165         return r;
 166 }
 167
 168 static bool path_spec_check_good(PathSpec *s, bool initial) {
 169         bool good = false;
 170
 171         switch (s->type) {
 172
 173         case PATH_EXISTS:
 174                 good = access(s->path, F_OK) >= 0;
 175                 break;
 176
 177         case PATH_EXISTS_GLOB:
 178                 good = glob_exists(s->path) > 0;
 179                 break;
 180
 181         case PATH_DIRECTORY_NOT_EMPTY: {
 182                 int k;
 183
 184                 k = dir_is_empty(s->path);
 185                 good = !(k == -ENOENT || k > 0);
 186                 break;
 187         }
 188
 189         case PATH_CHANGED:
 190         case PATH_MODIFIED: {
 191                 bool b;
 192
 193                 b = access(s->path, F_OK) >= 0;
 194                 good = !initial && b != s->previous_exists;
 195                 s->previous_exists = b;
 196                 break;
 197         }
 198
 199         default:
 200                 ;
 201         }
 202
 203         return good;
 204 }
 205
 206 static bool path_spec_startswith(PathSpec *s, const char *what) {
 207         return path_startswith(s->path, what);
 208 }
 209
 210 static void path_spec_mkdir(PathSpec *s, mode_t mode) {
 211         int r;
 212
 213         if (s->type == PATH_EXISTS || s->type == PATH_EXISTS_GLOB)
 214                 return;
 215
 216         if ((r = mkdir_p(s->path, mode)) < 0)
 217                 log_warning("mkdir(%s) failed: %s", s->path, strerror(-r));
 218 }
 219
 220 static void path_spec_dump(PathSpec *s, FILE *f, const char *prefix) {
 221         fprintf(f,
 222                 "%s%s: %s\n",
 223                 prefix,
 224                 path_type_to_string(s->type),
 225                 s->path);
 226 }
 227
 228 void path_spec_done(PathSpec *s) {
 229         assert(s);
 230         assert(s->inotify_fd == -1);
 231
 232         free(s->path);
 233 }
 234
 235 static void path_init(Unit *u) {
 236         Path *p = PATH(u);
 237
 238         assert(u);
 239         assert(u->load_state == UNIT_STUB);
 240
 241         p->directory_mode = 0755;
 242 }
 243
 244 static void path_done(Unit *u) {
 245         Path *p = PATH(u);
 246         PathSpec *s;
 247
 248         assert(p);
 249
 250         unit_ref_unset(&p->unit);
 251
 252         while ((s = p->specs)) {
 253                 path_spec_unwatch(s, u);
 254                 LIST_REMOVE(PathSpec, spec, p->specs, s);
 255                 path_spec_done(s);
 256                 free(s);
 257         }
 258 }
 259
 260 int path_add_one_mount_link(Path *p, Mount *m) {
 261         PathSpec *s;
 262         int r;
 263
 264         assert(p);
 265         assert(m);
 266
 267         if (p->meta.load_state != UNIT_LOADED ||
 268             m->meta.load_state != UNIT_LOADED)
 269                 return 0;
 270
 271         LIST_FOREACH(spec, s, p->specs) {
 272
 273                 if (!path_spec_startswith(s, m->where))
 274                         continue;
 275
 276                 if ((r = unit_add_two_dependencies(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, UNIT(m), true)) < 0)
 277                         return r;
 278         }
 279
 280         return 0;
 281 }
 282
 283 static int path_add_mount_links(Path *p) {
 284         Unit *other;
 285         int r;
 286
 287         assert(p);
 288
 289         LIST_FOREACH(units_by_type, other, p->meta.manager->units_by_type[UNIT_MOUNT])
 290                 if ((r = path_add_one_mount_link(p, (Mount*) other)) < 0)
 291                         return r;
 292
 293         return 0;
 294 }
 295
 296 static int path_verify(Path *p) {
 297         assert(p);
 298
 299         if (p->meta.load_state != UNIT_LOADED)
 300                 return 0;
 301
 302         if (!p->specs) {
 303                 log_error("%s lacks path setting. Refusing.", p->meta.id);
 304                 return -EINVAL;
 305         }
 306
 307         return 0;
 308 }
 309
 310 static int path_add_default_dependencies(Path *p) {
 311         int r;
 312
 313         assert(p);
 314
 315         if (p->meta.manager->running_as == MANAGER_SYSTEM) {
 316                 if ((r = unit_add_dependency_by_name(UNIT(p), UNIT_BEFORE, SPECIAL_BASIC_TARGET, NULL, true)) < 0)
 317                         return r;
 318
 319                 if ((r = unit_add_two_dependencies_by_name(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, NULL, true)) < 0)
 320                         return r;
 321         }
 322
 323         return unit_add_two_dependencies_by_name(UNIT(p), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true);
 324 }
 325
 326 static int path_load(Unit *u) {
 327         Path *p = PATH(u);
 328         int r;
 329
 330         assert(u);
 331         assert(u->load_state == UNIT_STUB);
 332
 333         if ((r = unit_load_fragment_and_dropin(u)) < 0)
 334                 return r;
 335
 336         if (u->load_state == UNIT_LOADED) {
 337
 338                 if (!UNIT_DEREF(p->unit)) {
 339                         Unit *x;
 340
 341                         r = unit_load_related_unit(u, ".service", &x);
 342                         if (r < 0)
 343                                 return r;
 344
 345                         unit_ref_set(&p->unit, x);
 346                 }
 347
 348                 r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, UNIT_DEREF(p->unit), true);
 349                 if (r < 0)
 350                         return r;
 351
 352                 if ((r = path_add_mount_links(p)) < 0)
 353                         return r;
 354
 355                 if (p->meta.default_dependencies)
 356                         if ((r = path_add_default_dependencies(p)) < 0)
 357                                 return r;
 358         }
 359
 360         return path_verify(p);
 361 }
 362
 363 static void path_dump(Unit *u, FILE *f, const char *prefix) {
 364         Path *p = PATH(u);
 365         PathSpec *s;
 366
 367         assert(p);
 368         assert(f);
 369
 370         fprintf(f,
 371                 "%sPath State: %s\n"
 372                 "%sUnit: %s\n"
 373                 "%sMakeDirectory: %s\n"
 374                 "%sDirectoryMode: %04o\n",
 375                 prefix, path_state_to_string(p->state),
 376                 prefix, UNIT_DEREF(p->unit)->id,
 377                 prefix, yes_no(p->make_directory),
 378                 prefix, p->directory_mode);
 379
 380         LIST_FOREACH(spec, s, p->specs)
 381                 path_spec_dump(s, f, prefix);
 382 }
 383
 384 static void path_unwatch(Path *p) {
 385         PathSpec *s;
 386
 387         assert(p);
 388
 389         LIST_FOREACH(spec, s, p->specs)
 390                 path_spec_unwatch(s, UNIT(p));
 391 }
 392
 393 static int path_watch(Path *p) {
 394         int r;
 395         PathSpec *s;
 396
 397         assert(p);
 398
 399         LIST_FOREACH(spec, s, p->specs)
 400                 if ((r = path_spec_watch(s, UNIT(p))) < 0)
 401                         return r;
 402
 403         return 0;
 404 }
 405
 406 static void path_set_state(Path *p, PathState state) {
 407         PathState old_state;
 408         assert(p);
 409
 410         old_state = p->state;
 411         p->state = state;
 412
 413         if (state != PATH_WAITING &&
 414             (state != PATH_RUNNING || p->inotify_triggered))
 415                 path_unwatch(p);
 416
 417         if (state != old_state)
 418                 log_debug("%s changed %s -> %s",
 419                           p->meta.id,
 420                           path_state_to_string(old_state),
 421                           path_state_to_string(state));
 422
 423         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state], true);
 424 }
 425
 426 static void path_enter_waiting(Path *p, bool initial, bool recheck);
 427
 428 static int path_coldplug(Unit *u) {
 429         Path *p = PATH(u);
 430
 431         assert(p);
 432         assert(p->state == PATH_DEAD);
 433
 434         if (p->deserialized_state != p->state) {
 435
 436                 if (p->deserialized_state == PATH_WAITING ||
 437                     p->deserialized_state == PATH_RUNNING)
 438                         path_enter_waiting(p, true, true);
 439                 else
 440                         path_set_state(p, p->deserialized_state);
 441         }
 442
 443         return 0;
 444 }
 445
 446 static void path_enter_dead(Path *p, bool success) {
 447         assert(p);
 448
 449         if (!success)
 450                 p->failure = true;
 451
 452         path_set_state(p, p->failure ? PATH_FAILED : PATH_DEAD);
 453 }
 454
 455 static void path_enter_running(Path *p) {
 456         int r;
 457         DBusError error;
 458
 459         assert(p);
 460         dbus_error_init(&error);
 461
 462         /* Don't start job if we are supposed to go down */
 463         if (p->meta.job && p->meta.job->type == JOB_STOP)
 464                 return;
 465
 466         if ((r = manager_add_job(p->meta.manager, JOB_START, UNIT_DEREF(p->unit), JOB_REPLACE, true, &error, NULL)) < 0)
 467                 goto fail;
 468
 469         p->inotify_triggered = false;
 470
 471         if ((r = path_watch(p)) < 0)
 472                 goto fail;
 473
 474         path_set_state(p, PATH_RUNNING);
 475         return;
 476
 477 fail:
 478         log_warning("%s failed to queue unit startup job: %s", p->meta.id, bus_error(&error, r));
 479         path_enter_dead(p, false);
 480
 481         dbus_error_free(&error);
 482 }
 483
 484 static bool path_check_good(Path *p, bool initial) {
 485         PathSpec *s;
 486         bool good = false;
 487
 488         assert(p);
 489
 490         LIST_FOREACH(spec, s, p->specs) {
 491                 good = path_spec_check_good(s, initial);
 492
 493                 if (good)
 494                         break;
 495         }
 496
 497         return good;
 498 }
 499
 500 static void path_enter_waiting(Path *p, bool initial, bool recheck) {
 501         int r;
 502
 503         if (recheck)
 504                 if (path_check_good(p, initial)) {
 505                         log_debug("%s got triggered.", p->meta.id);
 506                         path_enter_running(p);
 507                         return;
 508                 }
 509
 510         if ((r = path_watch(p)) < 0)
 511                 goto fail;
 512
 513         /* Hmm, so now we have created inotify watches, but the file
 514          * might have appeared/been removed by now, so we must
 515          * recheck */
 516
 517         if (recheck)
 518                 if (path_check_good(p, false)) {
 519                         log_debug("%s got triggered.", p->meta.id);
 520                         path_enter_running(p);
 521                         return;
 522                 }
 523
 524         path_set_state(p, PATH_WAITING);
 525         return;
 526
 527 fail:
 528         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 529         path_enter_dead(p, false);
 530 }
 531
 532 static void path_mkdir(Path *p) {
 533         PathSpec *s;
 534
 535         assert(p);
 536
 537         if (!p->make_directory)
 538                 return;
 539
 540         LIST_FOREACH(spec, s, p->specs)
 541                 path_spec_mkdir(s, p->directory_mode);
 542 }
 543
 544 static int path_start(Unit *u) {
 545         Path *p = PATH(u);
 546
 547         assert(p);
 548         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 549
 550         if (UNIT_DEREF(p->unit)->load_state != UNIT_LOADED)
 551                 return -ENOENT;
 552
 553         path_mkdir(p);
 554
 555         p->failure = false;
 556         path_enter_waiting(p, true, true);
 557
 558         return 0;
 559 }
 560
 561 static int path_stop(Unit *u) {
 562         Path *p = PATH(u);
 563
 564         assert(p);
 565         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 566
 567         path_enter_dead(p, true);
 568         return 0;
 569 }
 570
 571 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 572         Path *p = PATH(u);
 573
 574         assert(u);
 575         assert(f);
 576         assert(fds);
 577
 578         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 579
 580         return 0;
 581 }
 582
 583 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 584         Path *p = PATH(u);
 585
 586         assert(u);
 587         assert(key);
 588         assert(value);
 589         assert(fds);
 590
 591         if (streq(key, "state")) {
 592                 PathState state;
 593
 594                 if ((state = path_state_from_string(value)) < 0)
 595                         log_debug("Failed to parse state value %s", value);
 596                 else
 597                         p->deserialized_state = state;
 598         } else
 599                 log_debug("Unknown serialization key '%s'", key);
 600
 601         return 0;
 602 }
 603
 604 static UnitActiveState path_active_state(Unit *u) {
 605         assert(u);
 606
 607         return state_translation_table[PATH(u)->state];
 608 }
 609
 610 static const char *path_sub_state_to_string(Unit *u) {
 611         assert(u);
 612
 613         return path_state_to_string(PATH(u)->state);
 614 }
 615
 616 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 617         Path *p = PATH(u);
 618         PathSpec *s;
 619         int changed;
 620
 621         assert(p);
 622         assert(fd >= 0);
 623
 624         if (p->state != PATH_WAITING &&
 625             p->state != PATH_RUNNING)
 626                 return;
 627
 628         /* log_debug("inotify wakeup on %s.", u->id); */
 629
 630         LIST_FOREACH(spec, s, p->specs)
 631                 if (path_spec_owns_inotify_fd(s, fd))
 632                         break;
 633
 634         if (!s) {
 635                 log_error("Got event on unknown fd.");
 636                 goto fail;
 637         }
 638
 639         changed = path_spec_fd_event(s, events);
 640         if (changed < 0)
 641                 goto fail;
 642
 643         /* If we are already running, then remember that one event was
 644          * dispatched so that we restart the service only if something
 645          * actually changed on disk */
 646         p->inotify_triggered = true;
 647
 648         if (changed)
 649                 path_enter_running(p);
 650         else
 651                 path_enter_waiting(p, false, true);
 652
 653         return;
 654
 655 fail:
 656         path_enter_dead(p, false);
 657 }
 658
 659 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 660         Iterator i;
 661         Unit *k;
 662
 663         if (u->type == UNIT_PATH)
 664                 return;
 665
 666         SET_FOREACH(k, u->dependencies[UNIT_TRIGGERED_BY], i) {
 667                 Path *p;
 668
 669                 if (k->type != UNIT_PATH)
 670                         continue;
 671
 672                 if (k->load_state != UNIT_LOADED)
 673                         continue;
 674
 675                 p = PATH(k);
 676
 677                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 678                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 679
 680                         /* Hmm, so inotify was triggered since the
 681                          * last activation, so I guess we need to
 682                          * recheck what is going on. */
 683                         path_enter_waiting(p, false, p->inotify_triggered);
 684                 }
 685         }
 686 }
 687
 688 static void path_reset_failed(Unit *u) {
 689         Path *p = PATH(u);
 690
 691         assert(p);
 692
 693         if (p->state == PATH_FAILED)
 694                 path_set_state(p, PATH_DEAD);
 695
 696         p->failure = false;
 697 }
 698
 699 static const char* const path_state_table[_PATH_STATE_MAX] = {
 700         [PATH_DEAD] = "dead",
 701         [PATH_WAITING] = "waiting",
 702         [PATH_RUNNING] = "running",
 703         [PATH_FAILED] = "failed"
 704 };
 705
 706 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 707
 708 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 709         [PATH_EXISTS] = "PathExists",
 710         [PATH_EXISTS_GLOB] = "PathExistsGlob",
 711         [PATH_CHANGED] = "PathChanged",
 712         [PATH_MODIFIED] = "PathModified",
 713         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 714 };
 715
 716 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 717
 718 const UnitVTable path_vtable = {
 719         .suffix = ".path",
 720         .object_size = sizeof(Path),
 721         .sections =
 722                 "Unit\0"
 723                 "Path\0"
 724                 "Install\0",
 725
 726         .init = path_init,
 727         .done = path_done,
 728         .load = path_load,
 729
 730         .coldplug = path_coldplug,
 731
 732         .dump = path_dump,
 733
 734         .start = path_start,
 735         .stop = path_stop,
 736
 737         .serialize = path_serialize,
 738         .deserialize_item = path_deserialize_item,
 739
 740         .active_state = path_active_state,
 741         .sub_state_to_string = path_sub_state_to_string,
 742
 743         .fd_event = path_fd_event,
 744
 745         .reset_failed = path_reset_failed,
 746
 747         .bus_interface = "org.freedesktop.systemd1.Path",
 748         .bus_message_handler = bus_path_message_handler
 749 };