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