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_MODIFIED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO|IN_MODIFY,
  48                 [PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO
  49         };
  50
  51         bool exists = false;
  52         char *k, *slash;
  53         int r;
  54
  55         assert(u);
  56         assert(s);
  57
  58         pathspec_unwatch(s, u);
  59
  60         if (!(k = strdup(s->path)))
  61                 return -ENOMEM;
  62
  63         if ((s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC)) < 0) {
  64                 r = -errno;
  65                 goto fail;
  66         }
  67
  68         if (unit_watch_fd(u, s->inotify_fd, EPOLLIN, &s->watch) < 0) {
  69                 r = -errno;
  70                 goto fail;
  71         }
  72
  73         if ((s->primary_wd = inotify_add_watch(s->inotify_fd, k, flags_table[s->type])) >= 0)
  74                 exists = true;
  75
  76         do {
  77                 int flags;
  78
  79                 /* This assumes the path was passed through path_kill_slashes()! */
  80                 if (!(slash = strrchr(k, '/')))
  81                         break;
  82
  83                 /* Trim the path at the last slash. Keep the slash if it's the root dir. */
  84                 slash[slash == k] = 0;
  85
  86                 flags = IN_MOVE_SELF;
  87                 if (!exists)
  88                         flags |= IN_DELETE_SELF | IN_ATTRIB | IN_CREATE | IN_MOVED_TO;
  89
  90                 if (inotify_add_watch(s->inotify_fd, k, flags) >= 0)
  91                         exists = true;
  92         } while (slash != k);
  93
  94         return 0;
  95
  96 fail:
  97         free(k);
  98
  99         pathspec_unwatch(s, u);
 100         return r;
 101 }
 102
 103 void pathspec_unwatch(PathSpec *s, Unit *u) {
 104
 105         if (s->inotify_fd < 0)
 106                 return;
 107
 108         unit_unwatch_fd(u, &s->watch);
 109
 110         close_nointr_nofail(s->inotify_fd);
 111         s->inotify_fd = -1;
 112 }
 113
 114 int pathspec_fd_event(PathSpec *s, uint32_t events) {
 115         uint8_t *buf = NULL;
 116         struct inotify_event *e;
 117         ssize_t k;
 118         int l;
 119         int r = 0;
 120
 121         if (events != EPOLLIN) {
 122                 log_error("Got Invalid poll event on inotify.");
 123                 r = -EINVAL;
 124                 goto out;
 125         }
 126
 127         if (ioctl(s->inotify_fd, FIONREAD, &l) < 0) {
 128                 log_error("FIONREAD failed: %m");
 129                 r = -errno;
 130                 goto out;
 131         }
 132
 133         assert(l > 0);
 134
 135         if (!(buf = malloc(l))) {
 136                 log_error("Failed to allocate buffer: %m");
 137                 r = -errno;
 138                 goto out;
 139         }
 140
 141         if ((k = read(s->inotify_fd, buf, l)) < 0) {
 142                 log_error("Failed to read inotify event: %m");
 143                 r = -errno;
 144                 goto out;
 145         }
 146
 147         e = (struct inotify_event*) buf;
 148
 149         while (k > 0) {
 150                 size_t step;
 151
 152                 if (s->type == PATH_CHANGED && s->primary_wd == e->wd)
 153                         r = 1;
 154
 155                 step = sizeof(struct inotify_event) + e->len;
 156                 assert(step <= (size_t) k);
 157
 158                 e = (struct inotify_event*) ((uint8_t*) e + step);
 159                 k -= step;
 160         }
 161 out:
 162         free(buf);
 163         return r;
 164 }
 165
 166 static bool pathspec_check_good(PathSpec *s, bool initial) {
 167         bool good = false;
 168
 169         switch (s->type) {
 170
 171         case PATH_EXISTS:
 172                 good = access(s->path, F_OK) >= 0;
 173                 break;
 174
 175         case PATH_EXISTS_GLOB:
 176                 good = glob_exists(s->path) > 0;
 177                 break;
 178
 179         case PATH_DIRECTORY_NOT_EMPTY: {
 180                 int k;
 181
 182                 k = dir_is_empty(s->path);
 183                 good = !(k == -ENOENT || k > 0);
 184                 break;
 185         }
 186
 187         case PATH_CHANGED: {
 188                 bool b;
 189
 190                 b = access(s->path, F_OK) >= 0;
 191                 good = !initial && b != s->previous_exists;
 192                 s->previous_exists = b;
 193                 break;
 194         }
 195
 196         default:
 197                 ;
 198         }
 199
 200         return good;
 201 }
 202
 203 static bool pathspec_startswith(PathSpec *s, const char *what) {
 204         return path_startswith(s->path, what);
 205 }
 206
 207 static void pathspec_mkdir(PathSpec *s, mode_t mode) {
 208         int r;
 209
 210         if (s->type == PATH_EXISTS || s->type == PATH_EXISTS_GLOB)
 211                 return;
 212
 213         if ((r = mkdir_p(s->path, mode)) < 0)
 214                 log_warning("mkdir(%s) failed: %s", s->path, strerror(-r));
 215 }
 216
 217 static void pathspec_dump(PathSpec *s, FILE *f, const char *prefix) {
 218         fprintf(f,
 219                 "%s%s: %s\n",
 220                 prefix,
 221                 path_type_to_string(s->type),
 222                 s->path);
 223 }
 224
 225 void pathspec_done(PathSpec *s) {
 226         assert(s->inotify_fd == -1);
 227         free(s->path);
 228 }
 229
 230 static void path_init(Unit *u) {
 231         Path *p = PATH(u);
 232
 233         assert(u);
 234         assert(u->meta.load_state == UNIT_STUB);
 235
 236         p->directory_mode = 0755;
 237 }
 238
 239 static void path_done(Unit *u) {
 240         Path *p = PATH(u);
 241         PathSpec *s;
 242
 243         assert(p);
 244
 245         while ((s = p->specs)) {
 246                 pathspec_unwatch(s, u);
 247                 LIST_REMOVE(PathSpec, spec, p->specs, s);
 248                 pathspec_done(s);
 249                 free(s);
 250         }
 251 }
 252
 253 int path_add_one_mount_link(Path *p, Mount *m) {
 254         PathSpec *s;
 255         int r;
 256
 257         assert(p);
 258         assert(m);
 259
 260         if (p->meta.load_state != UNIT_LOADED ||
 261             m->meta.load_state != UNIT_LOADED)
 262                 return 0;
 263
 264         LIST_FOREACH(spec, s, p->specs) {
 265
 266                 if (!pathspec_startswith(s, m->where))
 267                         continue;
 268
 269                 if ((r = unit_add_two_dependencies(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, UNIT(m), true)) < 0)
 270                         return r;
 271         }
 272
 273         return 0;
 274 }
 275
 276 static int path_add_mount_links(Path *p) {
 277         Meta *other;
 278         int r;
 279
 280         assert(p);
 281
 282         LIST_FOREACH(units_by_type, other, p->meta.manager->units_by_type[UNIT_MOUNT])
 283                 if ((r = path_add_one_mount_link(p, (Mount*) other)) < 0)
 284                         return r;
 285
 286         return 0;
 287 }
 288
 289 static int path_verify(Path *p) {
 290         assert(p);
 291
 292         if (p->meta.load_state != UNIT_LOADED)
 293                 return 0;
 294
 295         if (!p->specs) {
 296                 log_error("%s lacks path setting. Refusing.", p->meta.id);
 297                 return -EINVAL;
 298         }
 299
 300         return 0;
 301 }
 302
 303 static int path_add_default_dependencies(Path *p) {
 304         int r;
 305
 306         assert(p);
 307
 308         if (p->meta.manager->running_as == MANAGER_SYSTEM) {
 309                 if ((r = unit_add_dependency_by_name(UNIT(p), UNIT_BEFORE, SPECIAL_BASIC_TARGET, NULL, true)) < 0)
 310                         return r;
 311
 312                 if ((r = unit_add_two_dependencies_by_name(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, NULL, true)) < 0)
 313                         return r;
 314         }
 315
 316         return unit_add_two_dependencies_by_name(UNIT(p), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true);
 317 }
 318
 319 static int path_load(Unit *u) {
 320         Path *p = PATH(u);
 321         int r;
 322
 323         assert(u);
 324         assert(u->meta.load_state == UNIT_STUB);
 325
 326         if ((r = unit_load_fragment_and_dropin(u)) < 0)
 327                 return r;
 328
 329         if (u->meta.load_state == UNIT_LOADED) {
 330
 331                 if (!p->unit)
 332                         if ((r = unit_load_related_unit(u, ".service", &p->unit)))
 333                                 return r;
 334
 335                 if ((r = unit_add_dependency(u, UNIT_BEFORE, p->unit, true)) < 0)
 336                         return r;
 337
 338                 if ((r = path_add_mount_links(p)) < 0)
 339                         return r;
 340
 341                 if (p->meta.default_dependencies)
 342                         if ((r = path_add_default_dependencies(p)) < 0)
 343                                 return r;
 344         }
 345
 346         return path_verify(p);
 347 }
 348
 349 static void path_dump(Unit *u, FILE *f, const char *prefix) {
 350         Path *p = PATH(u);
 351         PathSpec *s;
 352
 353         assert(p);
 354         assert(f);
 355
 356         fprintf(f,
 357                 "%sPath State: %s\n"
 358                 "%sUnit: %s\n"
 359                 "%sMakeDirectory: %s\n"
 360                 "%sDirectoryMode: %04o\n",
 361                 prefix, path_state_to_string(p->state),
 362                 prefix, p->unit->meta.id,
 363                 prefix, yes_no(p->make_directory),
 364                 prefix, p->directory_mode);
 365
 366         LIST_FOREACH(spec, s, p->specs)
 367                 pathspec_dump(s, f, prefix);
 368 }
 369
 370 static void path_unwatch(Path *p) {
 371         PathSpec *s;
 372
 373         assert(p);
 374
 375         LIST_FOREACH(spec, s, p->specs)
 376                 pathspec_unwatch(s, UNIT(p));
 377 }
 378
 379 static int path_watch(Path *p) {
 380         int r;
 381         PathSpec *s;
 382
 383         assert(p);
 384
 385         LIST_FOREACH(spec, s, p->specs)
 386                 if ((r = pathspec_watch(s, UNIT(p))) < 0)
 387                         return r;
 388
 389         return 0;
 390 }
 391
 392 static void path_set_state(Path *p, PathState state) {
 393         PathState old_state;
 394         assert(p);
 395
 396         old_state = p->state;
 397         p->state = state;
 398
 399         if (state != PATH_WAITING &&
 400             (state != PATH_RUNNING || p->inotify_triggered))
 401                 path_unwatch(p);
 402
 403         if (state != old_state)
 404                 log_debug("%s changed %s -> %s",
 405                           p->meta.id,
 406                           path_state_to_string(old_state),
 407                           path_state_to_string(state));
 408
 409         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state], true);
 410 }
 411
 412 static void path_enter_waiting(Path *p, bool initial, bool recheck);
 413
 414 static int path_coldplug(Unit *u) {
 415         Path *p = PATH(u);
 416
 417         assert(p);
 418         assert(p->state == PATH_DEAD);
 419
 420         if (p->deserialized_state != p->state) {
 421
 422                 if (p->deserialized_state == PATH_WAITING ||
 423                     p->deserialized_state == PATH_RUNNING)
 424                         path_enter_waiting(p, true, true);
 425                 else
 426                         path_set_state(p, p->deserialized_state);
 427         }
 428
 429         return 0;
 430 }
 431
 432 static void path_enter_dead(Path *p, bool success) {
 433         assert(p);
 434
 435         if (!success)
 436                 p->failure = true;
 437
 438         path_set_state(p, p->failure ? PATH_FAILED : PATH_DEAD);
 439 }
 440
 441 static void path_enter_running(Path *p) {
 442         int r;
 443         DBusError error;
 444
 445         assert(p);
 446         dbus_error_init(&error);
 447
 448         /* Don't start job if we are supposed to go down */
 449         if (p->meta.job && p->meta.job->type == JOB_STOP)
 450                 return;
 451
 452         if ((r = manager_add_job(p->meta.manager, JOB_START, p->unit, JOB_REPLACE, true, &error, NULL)) < 0)
 453                 goto fail;
 454
 455         p->inotify_triggered = false;
 456
 457         if ((r = path_watch(p)) < 0)
 458                 goto fail;
 459
 460         path_set_state(p, PATH_RUNNING);
 461         return;
 462
 463 fail:
 464         log_warning("%s failed to queue unit startup job: %s", p->meta.id, bus_error(&error, r));
 465         path_enter_dead(p, false);
 466
 467         dbus_error_free(&error);
 468 }
 469
 470 static bool path_check_good(Path *p, bool initial) {
 471         PathSpec *s;
 472         bool good = false;
 473
 474         assert(p);
 475
 476         LIST_FOREACH(spec, s, p->specs) {
 477                 good = pathspec_check_good(s, initial);
 478
 479                 if (good)
 480                         break;
 481         }
 482
 483         return good;
 484 }
 485
 486 static void path_enter_waiting(Path *p, bool initial, bool recheck) {
 487         int r;
 488
 489         if (recheck)
 490                 if (path_check_good(p, initial)) {
 491                         log_debug("%s got triggered.", p->meta.id);
 492                         path_enter_running(p);
 493                         return;
 494                 }
 495
 496         if ((r = path_watch(p)) < 0)
 497                 goto fail;
 498
 499         /* Hmm, so now we have created inotify watches, but the file
 500          * might have appeared/been removed by now, so we must
 501          * recheck */
 502
 503         if (recheck)
 504                 if (path_check_good(p, false)) {
 505                         log_debug("%s got triggered.", p->meta.id);
 506                         path_enter_running(p);
 507                         return;
 508                 }
 509
 510         path_set_state(p, PATH_WAITING);
 511         return;
 512
 513 fail:
 514         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 515         path_enter_dead(p, false);
 516 }
 517
 518 static void path_mkdir(Path *p) {
 519         PathSpec *s;
 520
 521         assert(p);
 522
 523         if (!p->make_directory)
 524                 return;
 525
 526         LIST_FOREACH(spec, s, p->specs)
 527                 pathspec_mkdir(s, p->directory_mode);
 528 }
 529
 530 static int path_start(Unit *u) {
 531         Path *p = PATH(u);
 532
 533         assert(p);
 534         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 535
 536         if (p->unit->meta.load_state != UNIT_LOADED)
 537                 return -ENOENT;
 538
 539         path_mkdir(p);
 540
 541         p->failure = false;
 542         path_enter_waiting(p, true, true);
 543
 544         return 0;
 545 }
 546
 547 static int path_stop(Unit *u) {
 548         Path *p = PATH(u);
 549
 550         assert(p);
 551         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 552
 553         path_enter_dead(p, true);
 554         return 0;
 555 }
 556
 557 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 558         Path *p = PATH(u);
 559
 560         assert(u);
 561         assert(f);
 562         assert(fds);
 563
 564         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 565
 566         return 0;
 567 }
 568
 569 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 570         Path *p = PATH(u);
 571
 572         assert(u);
 573         assert(key);
 574         assert(value);
 575         assert(fds);
 576
 577         if (streq(key, "state")) {
 578                 PathState state;
 579
 580                 if ((state = path_state_from_string(value)) < 0)
 581                         log_debug("Failed to parse state value %s", value);
 582                 else
 583                         p->deserialized_state = state;
 584         } else
 585                 log_debug("Unknown serialization key '%s'", key);
 586
 587         return 0;
 588 }
 589
 590 static UnitActiveState path_active_state(Unit *u) {
 591         assert(u);
 592
 593         return state_translation_table[PATH(u)->state];
 594 }
 595
 596 static const char *path_sub_state_to_string(Unit *u) {
 597         assert(u);
 598
 599         return path_state_to_string(PATH(u)->state);
 600 }
 601
 602 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 603         Path *p = PATH(u);
 604         PathSpec *s;
 605         int changed;
 606
 607         assert(p);
 608         assert(fd >= 0);
 609
 610         if (p->state != PATH_WAITING &&
 611             p->state != PATH_RUNNING)
 612                 return;
 613
 614         /* log_debug("inotify wakeup on %s.", u->meta.id); */
 615
 616         LIST_FOREACH(spec, s, p->specs)
 617                 if (pathspec_owns_inotify_fd(s, fd))
 618                         break;
 619
 620         if (!s) {
 621                 log_error("Got event on unknown fd.");
 622                 goto fail;
 623         }
 624
 625         changed = pathspec_fd_event(s, events);
 626         if (changed < 0)
 627                 goto fail;
 628
 629         /* If we are already running, then remember that one event was
 630          * dispatched so that we restart the service only if something
 631          * actually changed on disk */
 632         p->inotify_triggered = true;
 633
 634         if (changed)
 635                 path_enter_running(p);
 636         else
 637                 path_enter_waiting(p, false, true);
 638
 639         return;
 640
 641 fail:
 642         path_enter_dead(p, false);
 643 }
 644
 645 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 646         char *n;
 647         int r;
 648         Iterator i;
 649
 650         if (u->meta.type == UNIT_PATH)
 651                 return;
 652
 653         SET_FOREACH(n, u->meta.names, i) {
 654                 char *k;
 655                 Unit *t;
 656                 Path *p;
 657
 658                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 659                         r = -ENOMEM;
 660                         goto fail;
 661                 }
 662
 663                 t = manager_get_unit(u->meta.manager, k);
 664                 free(k);
 665
 666                 if (!t)
 667                         continue;
 668
 669                 if (t->meta.load_state != UNIT_LOADED)
 670                         continue;
 671
 672                 p = PATH(t);
 673
 674                 if (p->unit != u)
 675                         continue;
 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         return;
 688
 689 fail:
 690         log_error("Failed find path unit: %s", strerror(-r));
 691 }
 692
 693 static void path_reset_failed(Unit *u) {
 694         Path *p = PATH(u);
 695
 696         assert(p);
 697
 698         if (p->state == PATH_FAILED)
 699                 path_set_state(p, PATH_DEAD);
 700
 701         p->failure = false;
 702 }
 703
 704 static const char* const path_state_table[_PATH_STATE_MAX] = {
 705         [PATH_DEAD] = "dead",
 706         [PATH_WAITING] = "waiting",
 707         [PATH_RUNNING] = "running",
 708         [PATH_FAILED] = "failed"
 709 };
 710
 711 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 712
 713 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 714         [PATH_EXISTS] = "PathExists",
 715         [PATH_EXISTS_GLOB] = "PathExistsGlob",
 716         [PATH_CHANGED] = "PathChanged",
 717         [PATH_MODIFIED] = "PathModified",
 718         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 719 };
 720
 721 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 722
 723 const UnitVTable path_vtable = {
 724         .suffix = ".path",
 725         .sections =
 726                 "Unit\0"
 727                 "Path\0"
 728                 "Install\0",
 729
 730         .init = path_init,
 731         .done = path_done,
 732         .load = path_load,
 733
 734         .coldplug = path_coldplug,
 735
 736         .dump = path_dump,
 737
 738         .start = path_start,
 739         .stop = path_stop,
 740
 741         .serialize = path_serialize,
 742         .deserialize_item = path_deserialize_item,
 743
 744         .active_state = path_active_state,
 745         .sub_state_to_string = path_sub_state_to_string,
 746
 747         .fd_event = path_fd_event,
 748
 749         .reset_failed = path_reset_failed,
 750
 751         .bus_interface = "org.freedesktop.systemd1.Path",
 752         .bus_message_handler = bus_path_message_handler
 753 };