src/path.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/inotify.h>
  23 #include <sys/epoll.h>
  24 #include <sys/ioctl.h>
  25 #include <errno.h>
  26 #include <unistd.h>
  27
  28 #include "unit.h"
  29 #include "unit-name.h"
  30 #include "path.h"
  31 #include "dbus-path.h"
  32 #include "special.h"
  33 #include "bus-errors.h"
  34
  35 static const UnitActiveState state_translation_table[_PATH_STATE_MAX] = {
  36         [PATH_DEAD] = UNIT_INACTIVE,
  37         [PATH_WAITING] = UNIT_ACTIVE,
  38         [PATH_RUNNING] = UNIT_ACTIVE,
  39         [PATH_FAILED] = UNIT_FAILED
  40 };
  41
  42 static void path_init(Unit *u) {
  43         Path *p = PATH(u);
  44
  45         assert(u);
  46         assert(u->meta.load_state == UNIT_STUB);
  47
  48         p->directory_mode = 0755;
  49 }
  50
  51 static void path_unwatch_one(Path *p, PathSpec *s) {
  52
  53         if (s->inotify_fd < 0)
  54                 return;
  55
  56         unit_unwatch_fd(UNIT(p), &s->watch);
  57
  58         close_nointr_nofail(s->inotify_fd);
  59         s->inotify_fd = -1;
  60 }
  61
  62 static void path_done(Unit *u) {
  63         Path *p = PATH(u);
  64         PathSpec *s;
  65
  66         assert(p);
  67
  68         while ((s = p->specs)) {
  69                 path_unwatch_one(p, s);
  70                 LIST_REMOVE(PathSpec, spec, p->specs, s);
  71                 free(s->path);
  72                 free(s);
  73         }
  74 }
  75
  76 int path_add_one_mount_link(Path *p, Mount *m) {
  77         PathSpec *s;
  78         int r;
  79
  80         assert(p);
  81         assert(m);
  82
  83         if (p->meta.load_state != UNIT_LOADED ||
  84             m->meta.load_state != UNIT_LOADED)
  85                 return 0;
  86
  87         LIST_FOREACH(spec, s, p->specs) {
  88
  89                 if (!path_startswith(s->path, m->where))
  90                         continue;
  91
  92                 if ((r = unit_add_two_dependencies(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, UNIT(m), true)) < 0)
  93                         return r;
  94         }
  95
  96         return 0;
  97 }
  98
  99 static int path_add_mount_links(Path *p) {
 100         Meta *other;
 101         int r;
 102
 103         assert(p);
 104
 105         LIST_FOREACH(units_by_type, other, p->meta.manager->units_by_type[UNIT_MOUNT])
 106                 if ((r = path_add_one_mount_link(p, (Mount*) other)) < 0)
 107                         return r;
 108
 109         return 0;
 110 }
 111
 112 static int path_verify(Path *p) {
 113         assert(p);
 114
 115         if (p->meta.load_state != UNIT_LOADED)
 116                 return 0;
 117
 118         if (!p->specs) {
 119                 log_error("%s lacks path setting. Refusing.", p->meta.id);
 120                 return -EINVAL;
 121         }
 122
 123         return 0;
 124 }
 125
 126 static int path_add_default_dependencies(Path *p) {
 127         int r;
 128
 129         assert(p);
 130
 131         if (p->meta.manager->running_as == MANAGER_SYSTEM) {
 132                 if ((r = unit_add_dependency_by_name(UNIT(p), UNIT_BEFORE, SPECIAL_BASIC_TARGET, NULL, true)) < 0)
 133                         return r;
 134
 135                 if ((r = unit_add_two_dependencies_by_name(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, NULL, true)) < 0)
 136                         return r;
 137         }
 138
 139         return unit_add_two_dependencies_by_name(UNIT(p), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true);
 140 }
 141
 142 static int path_load(Unit *u) {
 143         Path *p = PATH(u);
 144         int r;
 145
 146         assert(u);
 147         assert(u->meta.load_state == UNIT_STUB);
 148
 149         if ((r = unit_load_fragment_and_dropin(u)) < 0)
 150                 return r;
 151
 152         if (u->meta.load_state == UNIT_LOADED) {
 153
 154                 if (!p->unit)
 155                         if ((r = unit_load_related_unit(u, ".service", &p->unit)))
 156                                 return r;
 157
 158                 if ((r = unit_add_dependency(u, UNIT_BEFORE, p->unit, true)) < 0)
 159                         return r;
 160
 161                 if ((r = path_add_mount_links(p)) < 0)
 162                         return r;
 163
 164                 if (p->meta.default_dependencies)
 165                         if ((r = path_add_default_dependencies(p)) < 0)
 166                                 return r;
 167         }
 168
 169         return path_verify(p);
 170 }
 171
 172 static void path_dump(Unit *u, FILE *f, const char *prefix) {
 173         Path *p = PATH(u);
 174         PathSpec *s;
 175
 176         assert(p);
 177         assert(f);
 178
 179         fprintf(f,
 180                 "%sPath State: %s\n"
 181                 "%sUnit: %s\n"
 182                 "%sMakeDirectory: %s\n"
 183                 "%sDirectoryMode: %04o\n",
 184                 prefix, path_state_to_string(p->state),
 185                 prefix, p->unit->meta.id,
 186                 prefix, yes_no(p->make_directory),
 187                 prefix, p->directory_mode);
 188
 189         LIST_FOREACH(spec, s, p->specs)
 190                 fprintf(f,
 191                         "%s%s: %s\n",
 192                         prefix,
 193                         path_type_to_string(s->type),
 194                         s->path);
 195 }
 196
 197 static int path_watch_one(Path *p, PathSpec *s) {
 198         static const int flags_table[_PATH_TYPE_MAX] = {
 199                 [PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
 200                 [PATH_EXISTS_GLOB] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB,
 201                 [PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
 202                 [PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO
 203         };
 204
 205         bool exists = false;
 206         char *k, *slash;
 207         int r;
 208
 209         assert(p);
 210         assert(s);
 211
 212         path_unwatch_one(p, s);
 213
 214         if (!(k = strdup(s->path)))
 215                 return -ENOMEM;
 216
 217         if ((s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC)) < 0) {
 218                 r = -errno;
 219                 goto fail;
 220         }
 221
 222         if (unit_watch_fd(UNIT(p), s->inotify_fd, EPOLLIN, &s->watch) < 0) {
 223                 r = -errno;
 224                 goto fail;
 225         }
 226
 227         if ((s->primary_wd = inotify_add_watch(s->inotify_fd, k, flags_table[s->type])) >= 0)
 228                 exists = true;
 229
 230         do {
 231                 int flags;
 232
 233                 /* This assumes the path was passed through path_kill_slashes()! */
 234                 if (!(slash = strrchr(k, '/')))
 235                         break;
 236
 237                 /* Trim the path at the last slash. Keep the slash if it's the root dir. */
 238                 slash[slash == k] = 0;
 239
 240                 flags = IN_MOVE_SELF;
 241                 if (!exists)
 242                         flags |= IN_DELETE_SELF | IN_ATTRIB | IN_CREATE | IN_MOVED_TO;
 243
 244                 if (inotify_add_watch(s->inotify_fd, k, flags) >= 0)
 245                         exists = true;
 246         } while (slash != k);
 247
 248         return 0;
 249
 250 fail:
 251         free(k);
 252
 253         path_unwatch_one(p, s);
 254         return r;
 255 }
 256
 257 static void path_unwatch(Path *p) {
 258         PathSpec *s;
 259
 260         assert(p);
 261
 262         LIST_FOREACH(spec, s, p->specs)
 263                 path_unwatch_one(p, s);
 264 }
 265
 266 static int path_watch(Path *p) {
 267         int r;
 268         PathSpec *s;
 269
 270         assert(p);
 271
 272         LIST_FOREACH(spec, s, p->specs)
 273                 if ((r = path_watch_one(p, s)) < 0)
 274                         return r;
 275
 276         return 0;
 277 }
 278
 279 static void path_set_state(Path *p, PathState state) {
 280         PathState old_state;
 281         assert(p);
 282
 283         old_state = p->state;
 284         p->state = state;
 285
 286         if (state != PATH_WAITING &&
 287             (state != PATH_RUNNING || p->inotify_triggered))
 288                 path_unwatch(p);
 289
 290         if (state != old_state)
 291                 log_debug("%s changed %s -> %s",
 292                           p->meta.id,
 293                           path_state_to_string(old_state),
 294                           path_state_to_string(state));
 295
 296         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state], true);
 297 }
 298
 299 static void path_enter_waiting(Path *p, bool initial, bool recheck);
 300
 301 static int path_coldplug(Unit *u) {
 302         Path *p = PATH(u);
 303
 304         assert(p);
 305         assert(p->state == PATH_DEAD);
 306
 307         if (p->deserialized_state != p->state) {
 308
 309                 if (p->deserialized_state == PATH_WAITING ||
 310                     p->deserialized_state == PATH_RUNNING)
 311                         path_enter_waiting(p, true, true);
 312                 else
 313                         path_set_state(p, p->deserialized_state);
 314         }
 315
 316         return 0;
 317 }
 318
 319 static void path_enter_dead(Path *p, bool success) {
 320         assert(p);
 321
 322         if (!success)
 323                 p->failure = true;
 324
 325         path_set_state(p, p->failure ? PATH_FAILED : PATH_DEAD);
 326 }
 327
 328 static void path_enter_running(Path *p) {
 329         int r;
 330         DBusError error;
 331
 332         assert(p);
 333         dbus_error_init(&error);
 334
 335         /* Don't start job if we are supposed to go down */
 336         if (p->meta.job && p->meta.job->type == JOB_STOP)
 337                 return;
 338
 339         if ((r = manager_add_job(p->meta.manager, JOB_START, p->unit, JOB_REPLACE, true, &error, NULL)) < 0)
 340                 goto fail;
 341
 342         p->inotify_triggered = false;
 343
 344         if ((r = path_watch(p)) < 0)
 345                 goto fail;
 346
 347         path_set_state(p, PATH_RUNNING);
 348         return;
 349
 350 fail:
 351         log_warning("%s failed to queue unit startup job: %s", p->meta.id, bus_error(&error, r));
 352         path_enter_dead(p, false);
 353
 354         dbus_error_free(&error);
 355 }
 356
 357 static bool path_check_good(Path *p, bool initial) {
 358         PathSpec *s;
 359         bool good = false;
 360
 361         assert(p);
 362
 363         LIST_FOREACH(spec, s, p->specs) {
 364
 365                 switch (s->type) {
 366
 367                 case PATH_EXISTS:
 368                         good = access(s->path, F_OK) >= 0;
 369                         break;
 370
 371                 case PATH_EXISTS_GLOB:
 372                         good = glob_exists(s->path) > 0;
 373                         break;
 374
 375                 case PATH_DIRECTORY_NOT_EMPTY: {
 376                         int k;
 377
 378                         k = dir_is_empty(s->path);
 379                         good = !(k == -ENOENT || k > 0);
 380                         break;
 381                 }
 382
 383                 case PATH_CHANGED: {
 384                         bool b;
 385
 386                         b = access(s->path, F_OK) >= 0;
 387                         good = !initial && b != s->previous_exists;
 388                         s->previous_exists = b;
 389                         break;
 390                 }
 391
 392                 default:
 393                         ;
 394                 }
 395
 396                 if (good)
 397                         break;
 398         }
 399
 400         return good;
 401 }
 402
 403 static void path_enter_waiting(Path *p, bool initial, bool recheck) {
 404         int r;
 405
 406         if (recheck)
 407                 if (path_check_good(p, initial)) {
 408                         log_debug("%s got triggered.", p->meta.id);
 409                         path_enter_running(p);
 410                         return;
 411                 }
 412
 413         if ((r = path_watch(p)) < 0)
 414                 goto fail;
 415
 416         /* Hmm, so now we have created inotify watches, but the file
 417          * might have appeared/been removed by now, so we must
 418          * recheck */
 419
 420         if (recheck)
 421                 if (path_check_good(p, false)) {
 422                         log_debug("%s got triggered.", p->meta.id);
 423                         path_enter_running(p);
 424                         return;
 425                 }
 426
 427         path_set_state(p, PATH_WAITING);
 428         return;
 429
 430 fail:
 431         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 432         path_enter_dead(p, false);
 433 }
 434
 435 static void path_mkdir(Path *p) {
 436         PathSpec *s;
 437
 438         assert(p);
 439
 440         if (!p->make_directory)
 441                 return;
 442
 443         LIST_FOREACH(spec, s, p->specs) {
 444                 int r;
 445
 446                 if (s->type == PATH_EXISTS || s->type == PATH_EXISTS_GLOB)
 447                         continue;
 448
 449                 if ((r = mkdir_p(s->path, p->directory_mode)) < 0)
 450                         log_warning("mkdir(%s) failed: %s", s->path, strerror(-r));
 451         }
 452 }
 453
 454 static int path_start(Unit *u) {
 455         Path *p = PATH(u);
 456
 457         assert(p);
 458         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 459
 460         if (p->unit->meta.load_state != UNIT_LOADED)
 461                 return -ENOENT;
 462
 463         path_mkdir(p);
 464
 465         p->failure = false;
 466         path_enter_waiting(p, true, true);
 467
 468         return 0;
 469 }
 470
 471 static int path_stop(Unit *u) {
 472         Path *p = PATH(u);
 473
 474         assert(p);
 475         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 476
 477         path_enter_dead(p, true);
 478         return 0;
 479 }
 480
 481 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 482         Path *p = PATH(u);
 483
 484         assert(u);
 485         assert(f);
 486         assert(fds);
 487
 488         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 489
 490         return 0;
 491 }
 492
 493 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 494         Path *p = PATH(u);
 495
 496         assert(u);
 497         assert(key);
 498         assert(value);
 499         assert(fds);
 500
 501         if (streq(key, "state")) {
 502                 PathState state;
 503
 504                 if ((state = path_state_from_string(value)) < 0)
 505                         log_debug("Failed to parse state value %s", value);
 506                 else
 507                         p->deserialized_state = state;
 508         } else
 509                 log_debug("Unknown serialization key '%s'", key);
 510
 511         return 0;
 512 }
 513
 514 static UnitActiveState path_active_state(Unit *u) {
 515         assert(u);
 516
 517         return state_translation_table[PATH(u)->state];
 518 }
 519
 520 static const char *path_sub_state_to_string(Unit *u) {
 521         assert(u);
 522
 523         return path_state_to_string(PATH(u)->state);
 524 }
 525
 526 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 527         Path *p = PATH(u);
 528         int l;
 529         ssize_t k;
 530         uint8_t *buf = NULL;
 531         struct inotify_event *e;
 532         PathSpec *s;
 533         bool changed;
 534
 535         assert(p);
 536         assert(fd >= 0);
 537
 538         if (p->state != PATH_WAITING &&
 539             p->state != PATH_RUNNING)
 540                 return;
 541
 542         /* log_debug("inotify wakeup on %s.", u->meta.id); */
 543
 544         if (events != EPOLLIN) {
 545                 log_error("Got Invalid poll event on inotify.");
 546                 goto fail;
 547         }
 548
 549         LIST_FOREACH(spec, s, p->specs)
 550                 if (s->inotify_fd == fd)
 551                         break;
 552
 553         if (!s) {
 554                 log_error("Got event on unknown fd.");
 555                 goto fail;
 556         }
 557
 558         if (ioctl(fd, FIONREAD, &l) < 0) {
 559                 log_error("FIONREAD failed: %s", strerror(errno));
 560                 goto fail;
 561         }
 562
 563         assert(l > 0);
 564
 565         if (!(buf = malloc(l))) {
 566                 log_error("Failed to allocate buffer: %s", strerror(-ENOMEM));
 567                 goto fail;
 568         }
 569
 570         if ((k = read(fd, buf, l)) < 0) {
 571                 log_error("Failed to read inotify event: %s", strerror(-errno));
 572                 goto fail;
 573         }
 574
 575         /* If we are already running, then remember that one event was
 576          * dispatched so that we restart the service only if something
 577          * actually changed on disk */
 578         p->inotify_triggered = true;
 579
 580         e = (struct inotify_event*) buf;
 581
 582         changed = false;
 583         while (k > 0) {
 584                 size_t step;
 585
 586                 if (s->type == PATH_CHANGED && s->primary_wd == e->wd)
 587                         changed = true;
 588
 589                 step = sizeof(struct inotify_event) + e->len;
 590                 assert(step <= (size_t) k);
 591
 592                 e = (struct inotify_event*) ((uint8_t*) e + step);
 593                 k -= step;
 594         }
 595
 596         if (changed)
 597                 path_enter_running(p);
 598         else
 599                 path_enter_waiting(p, false, true);
 600
 601         free(buf);
 602
 603         return;
 604
 605 fail:
 606         free(buf);
 607         path_enter_dead(p, false);
 608 }
 609
 610 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 611         char *n;
 612         int r;
 613         Iterator i;
 614
 615         if (u->meta.type == UNIT_PATH)
 616                 return;
 617
 618         SET_FOREACH(n, u->meta.names, i) {
 619                 char *k;
 620                 Unit *t;
 621                 Path *p;
 622
 623                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 624                         r = -ENOMEM;
 625                         goto fail;
 626                 }
 627
 628                 t = manager_get_unit(u->meta.manager, k);
 629                 free(k);
 630
 631                 if (!t)
 632                         continue;
 633
 634                 if (t->meta.load_state != UNIT_LOADED)
 635                         continue;
 636
 637                 p = PATH(t);
 638
 639                 if (p->unit != u)
 640                         continue;
 641
 642                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 643                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 644
 645                         /* Hmm, so inotify was triggered since the
 646                          * last activation, so I guess we need to
 647                          * recheck what is going on. */
 648                         path_enter_waiting(p, false, p->inotify_triggered);
 649                 }
 650         }
 651
 652         return;
 653
 654 fail:
 655         log_error("Failed find path unit: %s", strerror(-r));
 656 }
 657
 658 static void path_reset_failed(Unit *u) {
 659         Path *p = PATH(u);
 660
 661         assert(p);
 662
 663         if (p->state == PATH_FAILED)
 664                 path_set_state(p, PATH_DEAD);
 665
 666         p->failure = false;
 667 }
 668
 669 static const char* const path_state_table[_PATH_STATE_MAX] = {
 670         [PATH_DEAD] = "dead",
 671         [PATH_WAITING] = "waiting",
 672         [PATH_RUNNING] = "running",
 673         [PATH_FAILED] = "failed"
 674 };
 675
 676 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 677
 678 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 679         [PATH_EXISTS] = "PathExists",
 680         [PATH_EXISTS_GLOB] = "PathExistsGlob",
 681         [PATH_CHANGED] = "PathChanged",
 682         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 683 };
 684
 685 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 686
 687 const UnitVTable path_vtable = {
 688         .suffix = ".path",
 689
 690         .init = path_init,
 691         .done = path_done,
 692         .load = path_load,
 693
 694         .coldplug = path_coldplug,
 695
 696         .dump = path_dump,
 697
 698         .start = path_start,
 699         .stop = path_stop,
 700
 701         .serialize = path_serialize,
 702         .deserialize_item = path_deserialize_item,
 703
 704         .active_state = path_active_state,
 705         .sub_state_to_string = path_sub_state_to_string,
 706
 707         .fd_event = path_fd_event,
 708
 709         .reset_failed = path_reset_failed,
 710
 711         .bus_interface = "org.freedesktop.systemd1.Path",
 712         .bus_message_handler = bus_path_message_handler
 713 };