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->type == PATH_MODIFIED) &&
 153                     s->primary_wd == e->wd)
 154                         r = 1;
 155
 156                 step = sizeof(struct inotify_event) + e->len;
 157                 assert(step <= (size_t) k);
 158
 159                 e = (struct inotify_event*) ((uint8_t*) e + step);
 160                 k -= step;
 161         }
 162 out:
 163         free(buf);
 164         return r;
 165 }
 166
 167 static bool pathspec_check_good(PathSpec *s, bool initial) {
 168         bool good = false;
 169
 170         switch (s->type) {
 171
 172         case PATH_EXISTS:
 173                 good = access(s->path, F_OK) >= 0;
 174                 break;
 175
 176         case PATH_EXISTS_GLOB:
 177                 good = glob_exists(s->path) > 0;
 178                 break;
 179
 180         case PATH_DIRECTORY_NOT_EMPTY: {
 181                 int k;
 182
 183                 k = dir_is_empty(s->path);
 184                 good = !(k == -ENOENT || k > 0);
 185                 break;
 186         }
 187
 188         case PATH_CHANGED:
 189         case PATH_MODIFIED: {
 190                 bool b;
 191
 192                 b = access(s->path, F_OK) >= 0;
 193                 good = !initial && b != s->previous_exists;
 194                 s->previous_exists = b;
 195                 break;
 196         }
 197
 198         default:
 199                 ;
 200         }
 201
 202         return good;
 203 }
 204
 205 static bool pathspec_startswith(PathSpec *s, const char *what) {
 206         return path_startswith(s->path, what);
 207 }
 208
 209 static void pathspec_mkdir(PathSpec *s, mode_t mode) {
 210         int r;
 211
 212         if (s->type == PATH_EXISTS || s->type == PATH_EXISTS_GLOB)
 213                 return;
 214
 215         if ((r = mkdir_p(s->path, mode)) < 0)
 216                 log_warning("mkdir(%s) failed: %s", s->path, strerror(-r));
 217 }
 218
 219 static void pathspec_dump(PathSpec *s, FILE *f, const char *prefix) {
 220         fprintf(f,
 221                 "%s%s: %s\n",
 222                 prefix,
 223                 path_type_to_string(s->type),
 224                 s->path);
 225 }
 226
 227 void pathspec_done(PathSpec *s) {
 228         assert(s->inotify_fd == -1);
 229         free(s->path);
 230 }
 231
 232 static void path_init(Unit *u) {
 233         Path *p = PATH(u);
 234
 235         assert(u);
 236         assert(u->meta.load_state == UNIT_STUB);
 237
 238         p->directory_mode = 0755;
 239 }
 240
 241 static void path_done(Unit *u) {
 242         Path *p = PATH(u);
 243         PathSpec *s;
 244
 245         assert(p);
 246
 247         while ((s = p->specs)) {
 248                 pathspec_unwatch(s, u);
 249                 LIST_REMOVE(PathSpec, spec, p->specs, s);
 250                 pathspec_done(s);
 251                 free(s);
 252         }
 253 }
 254
 255 int path_add_one_mount_link(Path *p, Mount *m) {
 256         PathSpec *s;
 257         int r;
 258
 259         assert(p);
 260         assert(m);
 261
 262         if (p->meta.load_state != UNIT_LOADED ||
 263             m->meta.load_state != UNIT_LOADED)
 264                 return 0;
 265
 266         LIST_FOREACH(spec, s, p->specs) {
 267
 268                 if (!pathspec_startswith(s, m->where))
 269                         continue;
 270
 271                 if ((r = unit_add_two_dependencies(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, UNIT(m), true)) < 0)
 272                         return r;
 273         }
 274
 275         return 0;
 276 }
 277
 278 static int path_add_mount_links(Path *p) {
 279         Meta *other;
 280         int r;
 281
 282         assert(p);
 283
 284         LIST_FOREACH(units_by_type, other, p->meta.manager->units_by_type[UNIT_MOUNT])
 285                 if ((r = path_add_one_mount_link(p, (Mount*) other)) < 0)
 286                         return r;
 287
 288         return 0;
 289 }
 290
 291 static int path_verify(Path *p) {
 292         assert(p);
 293
 294         if (p->meta.load_state != UNIT_LOADED)
 295                 return 0;
 296
 297         if (!p->specs) {
 298                 log_error("%s lacks path setting. Refusing.", p->meta.id);
 299                 return -EINVAL;
 300         }
 301
 302         return 0;
 303 }
 304
 305 static int path_add_default_dependencies(Path *p) {
 306         int r;
 307
 308         assert(p);
 309
 310         if (p->meta.manager->running_as == MANAGER_SYSTEM) {
 311                 if ((r = unit_add_dependency_by_name(UNIT(p), UNIT_BEFORE, SPECIAL_BASIC_TARGET, NULL, true)) < 0)
 312                         return r;
 313
 314                 if ((r = unit_add_two_dependencies_by_name(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, NULL, true)) < 0)
 315                         return r;
 316         }
 317
 318         return unit_add_two_dependencies_by_name(UNIT(p), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true);
 319 }
 320
 321 static int path_load(Unit *u) {
 322         Path *p = PATH(u);
 323         int r;
 324
 325         assert(u);
 326         assert(u->meta.load_state == UNIT_STUB);
 327
 328         if ((r = unit_load_fragment_and_dropin(u)) < 0)
 329                 return r;
 330
 331         if (u->meta.load_state == UNIT_LOADED) {
 332
 333                 if (!p->unit)
 334                         if ((r = unit_load_related_unit(u, ".service", &p->unit)))
 335                                 return r;
 336
 337                 if ((r = unit_add_dependency(u, UNIT_BEFORE, p->unit, true)) < 0)
 338                         return r;
 339
 340                 if ((r = path_add_mount_links(p)) < 0)
 341                         return r;
 342
 343                 if (p->meta.default_dependencies)
 344                         if ((r = path_add_default_dependencies(p)) < 0)
 345                                 return r;
 346         }
 347
 348         return path_verify(p);
 349 }
 350
 351 static void path_dump(Unit *u, FILE *f, const char *prefix) {
 352         Path *p = PATH(u);
 353         PathSpec *s;
 354
 355         assert(p);
 356         assert(f);
 357
 358         fprintf(f,
 359                 "%sPath State: %s\n"
 360                 "%sUnit: %s\n"
 361                 "%sMakeDirectory: %s\n"
 362                 "%sDirectoryMode: %04o\n",
 363                 prefix, path_state_to_string(p->state),
 364                 prefix, p->unit->meta.id,
 365                 prefix, yes_no(p->make_directory),
 366                 prefix, p->directory_mode);
 367
 368         LIST_FOREACH(spec, s, p->specs)
 369                 pathspec_dump(s, f, prefix);
 370 }
 371
 372 static void path_unwatch(Path *p) {
 373         PathSpec *s;
 374
 375         assert(p);
 376
 377         LIST_FOREACH(spec, s, p->specs)
 378                 pathspec_unwatch(s, UNIT(p));
 379 }
 380
 381 static int path_watch(Path *p) {
 382         int r;
 383         PathSpec *s;
 384
 385         assert(p);
 386
 387         LIST_FOREACH(spec, s, p->specs)
 388                 if ((r = pathspec_watch(s, UNIT(p))) < 0)
 389                         return r;
 390
 391         return 0;
 392 }
 393
 394 static void path_set_state(Path *p, PathState state) {
 395         PathState old_state;
 396         assert(p);
 397
 398         old_state = p->state;
 399         p->state = state;
 400
 401         if (state != PATH_WAITING &&
 402             (state != PATH_RUNNING || p->inotify_triggered))
 403                 path_unwatch(p);
 404
 405         if (state != old_state)
 406                 log_debug("%s changed %s -> %s",
 407                           p->meta.id,
 408                           path_state_to_string(old_state),
 409                           path_state_to_string(state));
 410
 411         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state], true);
 412 }
 413
 414 static void path_enter_waiting(Path *p, bool initial, bool recheck);
 415
 416 static int path_coldplug(Unit *u) {
 417         Path *p = PATH(u);
 418
 419         assert(p);
 420         assert(p->state == PATH_DEAD);
 421
 422         if (p->deserialized_state != p->state) {
 423
 424                 if (p->deserialized_state == PATH_WAITING ||
 425                     p->deserialized_state == PATH_RUNNING)
 426                         path_enter_waiting(p, true, true);
 427                 else
 428                         path_set_state(p, p->deserialized_state);
 429         }
 430
 431         return 0;
 432 }
 433
 434 static void path_enter_dead(Path *p, bool success) {
 435         assert(p);
 436
 437         if (!success)
 438                 p->failure = true;
 439
 440         path_set_state(p, p->failure ? PATH_FAILED : PATH_DEAD);
 441 }
 442
 443 static void path_enter_running(Path *p) {
 444         int r;
 445         DBusError error;
 446
 447         assert(p);
 448         dbus_error_init(&error);
 449
 450         /* Don't start job if we are supposed to go down */
 451         if (p->meta.job && p->meta.job->type == JOB_STOP)
 452                 return;
 453
 454         if ((r = manager_add_job(p->meta.manager, JOB_START, p->unit, JOB_REPLACE, true, &error, NULL)) < 0)
 455                 goto fail;
 456
 457         p->inotify_triggered = false;
 458
 459         if ((r = path_watch(p)) < 0)
 460                 goto fail;
 461
 462         path_set_state(p, PATH_RUNNING);
 463         return;
 464
 465 fail:
 466         log_warning("%s failed to queue unit startup job: %s", p->meta.id, bus_error(&error, r));
 467         path_enter_dead(p, false);
 468
 469         dbus_error_free(&error);
 470 }
 471
 472 static bool path_check_good(Path *p, bool initial) {
 473         PathSpec *s;
 474         bool good = false;
 475
 476         assert(p);
 477
 478         LIST_FOREACH(spec, s, p->specs) {
 479                 good = pathspec_check_good(s, initial);
 480
 481                 if (good)
 482                         break;
 483         }
 484
 485         return good;
 486 }
 487
 488 static void path_enter_waiting(Path *p, bool initial, bool recheck) {
 489         int r;
 490
 491         if (recheck)
 492                 if (path_check_good(p, initial)) {
 493                         log_debug("%s got triggered.", p->meta.id);
 494                         path_enter_running(p);
 495                         return;
 496                 }
 497
 498         if ((r = path_watch(p)) < 0)
 499                 goto fail;
 500
 501         /* Hmm, so now we have created inotify watches, but the file
 502          * might have appeared/been removed by now, so we must
 503          * recheck */
 504
 505         if (recheck)
 506                 if (path_check_good(p, false)) {
 507                         log_debug("%s got triggered.", p->meta.id);
 508                         path_enter_running(p);
 509                         return;
 510                 }
 511
 512         path_set_state(p, PATH_WAITING);
 513         return;
 514
 515 fail:
 516         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 517         path_enter_dead(p, false);
 518 }
 519
 520 static void path_mkdir(Path *p) {
 521         PathSpec *s;
 522
 523         assert(p);
 524
 525         if (!p->make_directory)
 526                 return;
 527
 528         LIST_FOREACH(spec, s, p->specs)
 529                 pathspec_mkdir(s, p->directory_mode);
 530 }
 531
 532 static int path_start(Unit *u) {
 533         Path *p = PATH(u);
 534
 535         assert(p);
 536         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 537
 538         if (p->unit->meta.load_state != UNIT_LOADED)
 539                 return -ENOENT;
 540
 541         path_mkdir(p);
 542
 543         p->failure = false;
 544         path_enter_waiting(p, true, true);
 545
 546         return 0;
 547 }
 548
 549 static int path_stop(Unit *u) {
 550         Path *p = PATH(u);
 551
 552         assert(p);
 553         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 554
 555         path_enter_dead(p, true);
 556         return 0;
 557 }
 558
 559 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 560         Path *p = PATH(u);
 561
 562         assert(u);
 563         assert(f);
 564         assert(fds);
 565
 566         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 567
 568         return 0;
 569 }
 570
 571 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 572         Path *p = PATH(u);
 573
 574         assert(u);
 575         assert(key);
 576         assert(value);
 577         assert(fds);
 578
 579         if (streq(key, "state")) {
 580                 PathState state;
 581
 582                 if ((state = path_state_from_string(value)) < 0)
 583                         log_debug("Failed to parse state value %s", value);
 584                 else
 585                         p->deserialized_state = state;
 586         } else
 587                 log_debug("Unknown serialization key '%s'", key);
 588
 589         return 0;
 590 }
 591
 592 static UnitActiveState path_active_state(Unit *u) {
 593         assert(u);
 594
 595         return state_translation_table[PATH(u)->state];
 596 }
 597
 598 static const char *path_sub_state_to_string(Unit *u) {
 599         assert(u);
 600
 601         return path_state_to_string(PATH(u)->state);
 602 }
 603
 604 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 605         Path *p = PATH(u);
 606         PathSpec *s;
 607         int changed;
 608
 609         assert(p);
 610         assert(fd >= 0);
 611
 612         if (p->state != PATH_WAITING &&
 613             p->state != PATH_RUNNING)
 614                 return;
 615
 616         /* log_debug("inotify wakeup on %s.", u->meta.id); */
 617
 618         LIST_FOREACH(spec, s, p->specs)
 619                 if (pathspec_owns_inotify_fd(s, fd))
 620                         break;
 621
 622         if (!s) {
 623                 log_error("Got event on unknown fd.");
 624                 goto fail;
 625         }
 626
 627         changed = pathspec_fd_event(s, events);
 628         if (changed < 0)
 629                 goto fail;
 630
 631         /* If we are already running, then remember that one event was
 632          * dispatched so that we restart the service only if something
 633          * actually changed on disk */
 634         p->inotify_triggered = true;
 635
 636         if (changed)
 637                 path_enter_running(p);
 638         else
 639                 path_enter_waiting(p, false, true);
 640
 641         return;
 642
 643 fail:
 644         path_enter_dead(p, false);
 645 }
 646
 647 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 648         char *n;
 649         int r;
 650         Iterator i;
 651
 652         if (u->meta.type == UNIT_PATH)
 653                 return;
 654
 655         SET_FOREACH(n, u->meta.names, i) {
 656                 char *k;
 657                 Unit *t;
 658                 Path *p;
 659
 660                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 661                         r = -ENOMEM;
 662                         goto fail;
 663                 }
 664
 665                 t = manager_get_unit(u->meta.manager, k);
 666                 free(k);
 667
 668                 if (!t)
 669                         continue;
 670
 671                 if (t->meta.load_state != UNIT_LOADED)
 672                         continue;
 673
 674                 p = PATH(t);
 675
 676                 if (p->unit != u)
 677                         continue;
 678
 679                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 680                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 681
 682                         /* Hmm, so inotify was triggered since the
 683                          * last activation, so I guess we need to
 684                          * recheck what is going on. */
 685                         path_enter_waiting(p, false, p->inotify_triggered);
 686                 }
 687         }
 688
 689         return;
 690
 691 fail:
 692         log_error("Failed find path unit: %s", strerror(-r));
 693 }
 694
 695 static void path_reset_failed(Unit *u) {
 696         Path *p = PATH(u);
 697
 698         assert(p);
 699
 700         if (p->state == PATH_FAILED)
 701                 path_set_state(p, PATH_DEAD);
 702
 703         p->failure = false;
 704 }
 705
 706 static const char* const path_state_table[_PATH_STATE_MAX] = {
 707         [PATH_DEAD] = "dead",
 708         [PATH_WAITING] = "waiting",
 709         [PATH_RUNNING] = "running",
 710         [PATH_FAILED] = "failed"
 711 };
 712
 713 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 714
 715 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 716         [PATH_EXISTS] = "PathExists",
 717         [PATH_EXISTS_GLOB] = "PathExistsGlob",
 718         [PATH_CHANGED] = "PathChanged",
 719         [PATH_MODIFIED] = "PathModified",
 720         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 721 };
 722
 723 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 724
 725 const UnitVTable path_vtable = {
 726         .suffix = ".path",
 727         .sections =
 728                 "Unit\0"
 729                 "Path\0"
 730                 "Install\0",
 731
 732         .init = path_init,
 733         .done = path_done,
 734         .load = path_load,
 735
 736         .coldplug = path_coldplug,
 737
 738         .dump = path_dump,
 739
 740         .start = path_start,
 741         .stop = path_stop,
 742
 743         .serialize = path_serialize,
 744         .deserialize_item = path_deserialize_item,
 745
 746         .active_state = path_active_state,
 747         .sub_state_to_string = path_sub_state_to_string,
 748
 749         .fd_event = path_fd_event,
 750
 751         .reset_failed = path_reset_failed,
 752
 753         .bus_interface = "org.freedesktop.systemd1.Path",
 754         .bus_message_handler = bus_path_message_handler
 755 };