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 pathspec_watch(PathSpec *s, Unit *u) {
  43         static const int flags_table[_PATH_TYPE_MAX] = {
  44                 [PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
  45                 [PATH_EXISTS_GLOB] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
  46                 [PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
  47                 [PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO
  48         };
  49
  50         bool exists = false;
  51         char *k, *slash;
  52         int r;
  53
  54         assert(u);
  55         assert(s);
  56
  57         pathspec_unwatch(s, u);
  58
  59         if (!(k = strdup(s->path)))
  60                 return -ENOMEM;
  61
  62         if ((s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC)) < 0) {
  63                 r = -errno;
  64                 goto fail;
  65         }
  66
  67         if (unit_watch_fd(u, s->inotify_fd, EPOLLIN, &s->watch) < 0) {
  68                 r = -errno;
  69                 goto fail;
  70         }
  71
  72         if ((s->primary_wd = inotify_add_watch(s->inotify_fd, k, flags_table[s->type])) >= 0)
  73                 exists = true;
  74
  75         do {
  76                 int flags;
  77
  78                 /* This assumes the path was passed through path_kill_slashes()! */
  79                 if (!(slash = strrchr(k, '/')))
  80                         break;
  81
  82                 /* Trim the path at the last slash. Keep the slash if it's the root dir. */
  83                 slash[slash == k] = 0;
  84
  85                 flags = IN_MOVE_SELF;
  86                 if (!exists)
  87                         flags |= IN_DELETE_SELF | IN_ATTRIB | IN_CREATE | IN_MOVED_TO;
  88
  89                 if (inotify_add_watch(s->inotify_fd, k, flags) >= 0)
  90                         exists = true;
  91         } while (slash != k);
  92
  93         return 0;
  94
  95 fail:
  96         free(k);
  97
  98         pathspec_unwatch(s, u);
  99         return r;
 100 }
 101
 102 void pathspec_unwatch(PathSpec *s, Unit *u) {
 103
 104         if (s->inotify_fd < 0)
 105                 return;
 106
 107         unit_unwatch_fd(u, &s->watch);
 108
 109         close_nointr_nofail(s->inotify_fd);
 110         s->inotify_fd = -1;
 111 }
 112
 113 int pathspec_fd_event(PathSpec *s, uint32_t events) {
 114         uint8_t *buf = NULL;
 115         struct inotify_event *e;
 116         ssize_t k;
 117         int l;
 118         int r = 0;
 119
 120         if (events != EPOLLIN) {
 121                 log_error("Got Invalid poll event on inotify.");
 122                 r = -EINVAL;
 123                 goto out;
 124         }
 125
 126         if (ioctl(s->inotify_fd, FIONREAD, &l) < 0) {
 127                 log_error("FIONREAD failed: %m");
 128                 r = -errno;
 129                 goto out;
 130         }
 131
 132         assert(l > 0);
 133
 134         if (!(buf = malloc(l))) {
 135                 log_error("Failed to allocate buffer: %m");
 136                 r = -errno;
 137                 goto out;
 138         }
 139
 140         if ((k = read(s->inotify_fd, buf, l)) < 0) {
 141                 log_error("Failed to read inotify event: %m");
 142                 r = -errno;
 143                 goto out;
 144         }
 145
 146         e = (struct inotify_event*) buf;
 147
 148         while (k > 0) {
 149                 size_t step;
 150
 151                 if (s->type == PATH_CHANGED && s->primary_wd == e->wd)
 152                         r = 1;
 153
 154                 step = sizeof(struct inotify_event) + e->len;
 155                 assert(step <= (size_t) k);
 156
 157                 e = (struct inotify_event*) ((uint8_t*) e + step);
 158                 k -= step;
 159         }
 160 out:
 161         free(buf);
 162         return r;
 163 }
 164
 165 static bool pathspec_check_good(PathSpec *s, bool initial) {
 166         bool good = false;
 167
 168         switch (s->type) {
 169
 170         case PATH_EXISTS:
 171                 good = access(s->path, F_OK) >= 0;
 172                 break;
 173
 174         case PATH_EXISTS_GLOB:
 175                 good = glob_exists(s->path) > 0;
 176                 break;
 177
 178         case PATH_DIRECTORY_NOT_EMPTY: {
 179                 int k;
 180
 181                 k = dir_is_empty(s->path);
 182                 good = !(k == -ENOENT || k > 0);
 183                 break;
 184         }
 185
 186         case PATH_CHANGED: {
 187                 bool b;
 188
 189                 b = access(s->path, F_OK) >= 0;
 190                 good = !initial && b != s->previous_exists;
 191                 s->previous_exists = b;
 192                 break;
 193         }
 194
 195         default:
 196                 ;
 197         }
 198
 199         return good;
 200 }
 201
 202 static bool pathspec_startswith(PathSpec *s, const char *what) {
 203         return path_startswith(s->path, what);
 204 }
 205
 206 static void pathspec_mkdir(PathSpec *s, mode_t mode) {
 207         int r;
 208
 209         if (s->type == PATH_EXISTS || s->type == PATH_EXISTS_GLOB)
 210                 return;
 211
 212         if ((r = mkdir_p(s->path, mode)) < 0)
 213                 log_warning("mkdir(%s) failed: %s", s->path, strerror(-r));
 214 }
 215
 216 static void pathspec_dump(PathSpec *s, FILE *f, const char *prefix) {
 217         fprintf(f,
 218                 "%s%s: %s\n",
 219                 prefix,
 220                 path_type_to_string(s->type),
 221                 s->path);
 222 }
 223
 224 void pathspec_done(PathSpec *s) {
 225         assert(s->inotify_fd == -1);
 226         free(s->path);
 227 }
 228
 229 static void path_init(Unit *u) {
 230         Path *p = PATH(u);
 231
 232         assert(u);
 233         assert(u->meta.load_state == UNIT_STUB);
 234
 235         p->directory_mode = 0755;
 236 }
 237
 238 static void path_done(Unit *u) {
 239         Path *p = PATH(u);
 240         PathSpec *s;
 241
 242         assert(p);
 243
 244         while ((s = p->specs)) {
 245                 pathspec_unwatch(s, u);
 246                 LIST_REMOVE(PathSpec, spec, p->specs, s);
 247                 pathspec_done(s);
 248                 free(s);
 249         }
 250 }
 251
 252 int path_add_one_mount_link(Path *p, Mount *m) {
 253         PathSpec *s;
 254         int r;
 255
 256         assert(p);
 257         assert(m);
 258
 259         if (p->meta.load_state != UNIT_LOADED ||
 260             m->meta.load_state != UNIT_LOADED)
 261                 return 0;
 262
 263         LIST_FOREACH(spec, s, p->specs) {
 264
 265                 if (!pathspec_startswith(s, m->where))
 266                         continue;
 267
 268                 if ((r = unit_add_two_dependencies(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, UNIT(m), true)) < 0)
 269                         return r;
 270         }
 271
 272         return 0;
 273 }
 274
 275 static int path_add_mount_links(Path *p) {
 276         Meta *other;
 277         int r;
 278
 279         assert(p);
 280
 281         LIST_FOREACH(units_by_type, other, p->meta.manager->units_by_type[UNIT_MOUNT])
 282                 if ((r = path_add_one_mount_link(p, (Mount*) other)) < 0)
 283                         return r;
 284
 285         return 0;
 286 }
 287
 288 static int path_verify(Path *p) {
 289         assert(p);
 290
 291         if (p->meta.load_state != UNIT_LOADED)
 292                 return 0;
 293
 294         if (!p->specs) {
 295                 log_error("%s lacks path setting. Refusing.", p->meta.id);
 296                 return -EINVAL;
 297         }
 298
 299         return 0;
 300 }
 301
 302 static int path_add_default_dependencies(Path *p) {
 303         int r;
 304
 305         assert(p);
 306
 307         if (p->meta.manager->running_as == MANAGER_SYSTEM) {
 308                 if ((r = unit_add_dependency_by_name(UNIT(p), UNIT_BEFORE, SPECIAL_BASIC_TARGET, NULL, true)) < 0)
 309                         return r;
 310
 311                 if ((r = unit_add_two_dependencies_by_name(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, NULL, true)) < 0)
 312                         return r;
 313         }
 314
 315         return unit_add_two_dependencies_by_name(UNIT(p), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true);
 316 }
 317
 318 static int path_load(Unit *u) {
 319         Path *p = PATH(u);
 320         int r;
 321
 322         assert(u);
 323         assert(u->meta.load_state == UNIT_STUB);
 324
 325         if ((r = unit_load_fragment_and_dropin(u)) < 0)
 326                 return r;
 327
 328         if (u->meta.load_state == UNIT_LOADED) {
 329
 330                 if (!p->unit)
 331                         if ((r = unit_load_related_unit(u, ".service", &p->unit)))
 332                                 return r;
 333
 334                 if ((r = unit_add_dependency(u, UNIT_BEFORE, p->unit, true)) < 0)
 335                         return r;
 336
 337                 if ((r = path_add_mount_links(p)) < 0)
 338                         return r;
 339
 340                 if (p->meta.default_dependencies)
 341                         if ((r = path_add_default_dependencies(p)) < 0)
 342                                 return r;
 343         }
 344
 345         return path_verify(p);
 346 }
 347
 348 static void path_dump(Unit *u, FILE *f, const char *prefix) {
 349         Path *p = PATH(u);
 350         PathSpec *s;
 351
 352         assert(p);
 353         assert(f);
 354
 355         fprintf(f,
 356                 "%sPath State: %s\n"
 357                 "%sUnit: %s\n"
 358                 "%sMakeDirectory: %s\n"
 359                 "%sDirectoryMode: %04o\n",
 360                 prefix, path_state_to_string(p->state),
 361                 prefix, p->unit->meta.id,
 362                 prefix, yes_no(p->make_directory),
 363                 prefix, p->directory_mode);
 364
 365         LIST_FOREACH(spec, s, p->specs)
 366                 pathspec_dump(s, f, prefix);
 367 }
 368
 369 static void path_unwatch(Path *p) {
 370         PathSpec *s;
 371
 372         assert(p);
 373
 374         LIST_FOREACH(spec, s, p->specs)
 375                 pathspec_unwatch(s, UNIT(p));
 376 }
 377
 378 static int path_watch(Path *p) {
 379         int r;
 380         PathSpec *s;
 381
 382         assert(p);
 383
 384         LIST_FOREACH(spec, s, p->specs)
 385                 if ((r = pathspec_watch(s, UNIT(p))) < 0)
 386                         return r;
 387
 388         return 0;
 389 }
 390
 391 static void path_set_state(Path *p, PathState state) {
 392         PathState old_state;
 393         assert(p);
 394
 395         old_state = p->state;
 396         p->state = state;
 397
 398         if (state != PATH_WAITING &&
 399             (state != PATH_RUNNING || p->inotify_triggered))
 400                 path_unwatch(p);
 401
 402         if (state != old_state)
 403                 log_debug("%s changed %s -> %s",
 404                           p->meta.id,
 405                           path_state_to_string(old_state),
 406                           path_state_to_string(state));
 407
 408         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state], true);
 409 }
 410
 411 static void path_enter_waiting(Path *p, bool initial, bool recheck);
 412
 413 static int path_coldplug(Unit *u) {
 414         Path *p = PATH(u);
 415
 416         assert(p);
 417         assert(p->state == PATH_DEAD);
 418
 419         if (p->deserialized_state != p->state) {
 420
 421                 if (p->deserialized_state == PATH_WAITING ||
 422                     p->deserialized_state == PATH_RUNNING)
 423                         path_enter_waiting(p, true, true);
 424                 else
 425                         path_set_state(p, p->deserialized_state);
 426         }
 427
 428         return 0;
 429 }
 430
 431 static void path_enter_dead(Path *p, bool success) {
 432         assert(p);
 433
 434         if (!success)
 435                 p->failure = true;
 436
 437         path_set_state(p, p->failure ? PATH_FAILED : PATH_DEAD);
 438 }
 439
 440 static void path_enter_running(Path *p) {
 441         int r;
 442         DBusError error;
 443
 444         assert(p);
 445         dbus_error_init(&error);
 446
 447         /* Don't start job if we are supposed to go down */
 448         if (p->meta.job && p->meta.job->type == JOB_STOP)
 449                 return;
 450
 451         if ((r = manager_add_job(p->meta.manager, JOB_START, p->unit, JOB_REPLACE, true, &error, NULL)) < 0)
 452                 goto fail;
 453
 454         p->inotify_triggered = false;
 455
 456         if ((r = path_watch(p)) < 0)
 457                 goto fail;
 458
 459         path_set_state(p, PATH_RUNNING);
 460         return;
 461
 462 fail:
 463         log_warning("%s failed to queue unit startup job: %s", p->meta.id, bus_error(&error, r));
 464         path_enter_dead(p, false);
 465
 466         dbus_error_free(&error);
 467 }
 468
 469 static bool path_check_good(Path *p, bool initial) {
 470         PathSpec *s;
 471         bool good = false;
 472
 473         assert(p);
 474
 475         LIST_FOREACH(spec, s, p->specs) {
 476                 good = pathspec_check_good(s, initial);
 477
 478                 if (good)
 479                         break;
 480         }
 481
 482         return good;
 483 }
 484
 485 static void path_enter_waiting(Path *p, bool initial, bool recheck) {
 486         int r;
 487
 488         if (recheck)
 489                 if (path_check_good(p, initial)) {
 490                         log_debug("%s got triggered.", p->meta.id);
 491                         path_enter_running(p);
 492                         return;
 493                 }
 494
 495         if ((r = path_watch(p)) < 0)
 496                 goto fail;
 497
 498         /* Hmm, so now we have created inotify watches, but the file
 499          * might have appeared/been removed by now, so we must
 500          * recheck */
 501
 502         if (recheck)
 503                 if (path_check_good(p, false)) {
 504                         log_debug("%s got triggered.", p->meta.id);
 505                         path_enter_running(p);
 506                         return;
 507                 }
 508
 509         path_set_state(p, PATH_WAITING);
 510         return;
 511
 512 fail:
 513         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 514         path_enter_dead(p, false);
 515 }
 516
 517 static void path_mkdir(Path *p) {
 518         PathSpec *s;
 519
 520         assert(p);
 521
 522         if (!p->make_directory)
 523                 return;
 524
 525         LIST_FOREACH(spec, s, p->specs)
 526                 pathspec_mkdir(s, p->directory_mode);
 527 }
 528
 529 static int path_start(Unit *u) {
 530         Path *p = PATH(u);
 531
 532         assert(p);
 533         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 534
 535         if (p->unit->meta.load_state != UNIT_LOADED)
 536                 return -ENOENT;
 537
 538         path_mkdir(p);
 539
 540         p->failure = false;
 541         path_enter_waiting(p, true, true);
 542
 543         return 0;
 544 }
 545
 546 static int path_stop(Unit *u) {
 547         Path *p = PATH(u);
 548
 549         assert(p);
 550         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 551
 552         path_enter_dead(p, true);
 553         return 0;
 554 }
 555
 556 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 557         Path *p = PATH(u);
 558
 559         assert(u);
 560         assert(f);
 561         assert(fds);
 562
 563         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 564
 565         return 0;
 566 }
 567
 568 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 569         Path *p = PATH(u);
 570
 571         assert(u);
 572         assert(key);
 573         assert(value);
 574         assert(fds);
 575
 576         if (streq(key, "state")) {
 577                 PathState state;
 578
 579                 if ((state = path_state_from_string(value)) < 0)
 580                         log_debug("Failed to parse state value %s", value);
 581                 else
 582                         p->deserialized_state = state;
 583         } else
 584                 log_debug("Unknown serialization key '%s'", key);
 585
 586         return 0;
 587 }
 588
 589 static UnitActiveState path_active_state(Unit *u) {
 590         assert(u);
 591
 592         return state_translation_table[PATH(u)->state];
 593 }
 594
 595 static const char *path_sub_state_to_string(Unit *u) {
 596         assert(u);
 597
 598         return path_state_to_string(PATH(u)->state);
 599 }
 600
 601 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 602         Path *p = PATH(u);
 603         PathSpec *s;
 604         int changed;
 605
 606         assert(p);
 607         assert(fd >= 0);
 608
 609         if (p->state != PATH_WAITING &&
 610             p->state != PATH_RUNNING)
 611                 return;
 612
 613         /* log_debug("inotify wakeup on %s.", u->meta.id); */
 614
 615         LIST_FOREACH(spec, s, p->specs)
 616                 if (pathspec_owns_inotify_fd(s, fd))
 617                         break;
 618
 619         if (!s) {
 620                 log_error("Got event on unknown fd.");
 621                 goto fail;
 622         }
 623
 624         changed = pathspec_fd_event(s, events);
 625         if (changed < 0)
 626                 goto fail;
 627
 628         /* If we are already running, then remember that one event was
 629          * dispatched so that we restart the service only if something
 630          * actually changed on disk */
 631         p->inotify_triggered = true;
 632
 633         if (changed)
 634                 path_enter_running(p);
 635         else
 636                 path_enter_waiting(p, false, true);
 637
 638         return;
 639
 640 fail:
 641         path_enter_dead(p, false);
 642 }
 643
 644 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 645         char *n;
 646         int r;
 647         Iterator i;
 648
 649         if (u->meta.type == UNIT_PATH)
 650                 return;
 651
 652         SET_FOREACH(n, u->meta.names, i) {
 653                 char *k;
 654                 Unit *t;
 655                 Path *p;
 656
 657                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 658                         r = -ENOMEM;
 659                         goto fail;
 660                 }
 661
 662                 t = manager_get_unit(u->meta.manager, k);
 663                 free(k);
 664
 665                 if (!t)
 666                         continue;
 667
 668                 if (t->meta.load_state != UNIT_LOADED)
 669                         continue;
 670
 671                 p = PATH(t);
 672
 673                 if (p->unit != u)
 674                         continue;
 675
 676                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 677                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 678
 679                         /* Hmm, so inotify was triggered since the
 680                          * last activation, so I guess we need to
 681                          * recheck what is going on. */
 682                         path_enter_waiting(p, false, p->inotify_triggered);
 683                 }
 684         }
 685
 686         return;
 687
 688 fail:
 689         log_error("Failed find path unit: %s", strerror(-r));
 690 }
 691
 692 static void path_reset_failed(Unit *u) {
 693         Path *p = PATH(u);
 694
 695         assert(p);
 696
 697         if (p->state == PATH_FAILED)
 698                 path_set_state(p, PATH_DEAD);
 699
 700         p->failure = false;
 701 }
 702
 703 static const char* const path_state_table[_PATH_STATE_MAX] = {
 704         [PATH_DEAD] = "dead",
 705         [PATH_WAITING] = "waiting",
 706         [PATH_RUNNING] = "running",
 707         [PATH_FAILED] = "failed"
 708 };
 709
 710 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 711
 712 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 713         [PATH_EXISTS] = "PathExists",
 714         [PATH_EXISTS_GLOB] = "PathExistsGlob",
 715         [PATH_CHANGED] = "PathChanged",
 716         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 717 };
 718
 719 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 720
 721 const UnitVTable path_vtable = {
 722         .suffix = ".path",
 723         .sections =
 724                 "Unit\0"
 725                 "Path\0"
 726                 "Install\0",
 727
 728         .init = path_init,
 729         .done = path_done,
 730         .load = path_load,
 731
 732         .coldplug = path_coldplug,
 733
 734         .dump = path_dump,
 735
 736         .start = path_start,
 737         .stop = path_stop,
 738
 739         .serialize = path_serialize,
 740         .deserialize_item = path_deserialize_item,
 741
 742         .active_state = path_active_state,
 743         .sub_state_to_string = path_sub_state_to_string,
 744
 745         .fd_event = path_fd_event,
 746
 747         .reset_failed = path_reset_failed,
 748
 749         .bus_interface = "org.freedesktop.systemd1.Path",
 750         .bus_message_handler = bus_path_message_handler
 751 };