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_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
 201                 [PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CREATE|IN_MOVED_TO
 202         };
 203
 204         bool exists = false;
 205         char *k, *slash;
 206         int r;
 207
 208         assert(p);
 209         assert(s);
 210
 211         path_unwatch_one(p, s);
 212
 213         if (!(k = strdup(s->path)))
 214                 return -ENOMEM;
 215
 216         if ((s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC)) < 0) {
 217                 r = -errno;
 218                 goto fail;
 219         }
 220
 221         if (unit_watch_fd(UNIT(p), s->inotify_fd, EPOLLIN, &s->watch) < 0) {
 222                 r = -errno;
 223                 goto fail;
 224         }
 225
 226         if ((s->primary_wd = inotify_add_watch(s->inotify_fd, k, flags_table[s->type])) >= 0)
 227                 exists = true;
 228
 229         do {
 230                 int flags;
 231
 232                 /* This assumes the path was passed through path_kill_slashes()! */
 233                 if (!(slash = strrchr(k, '/')))
 234                         break;
 235
 236                 /* Trim the path at the last slash. Keep the slash if it's the root dir. */
 237                 slash[slash == k] = 0;
 238
 239                 flags = IN_MOVE_SELF;
 240                 if (!exists)
 241                         flags |= IN_DELETE_SELF | IN_ATTRIB | IN_CREATE | IN_MOVED_TO;
 242
 243                 if (inotify_add_watch(s->inotify_fd, k, flags) >= 0)
 244                         exists = true;
 245         } while (slash != k);
 246
 247         return 0;
 248
 249 fail:
 250         free(k);
 251
 252         path_unwatch_one(p, s);
 253         return r;
 254 }
 255
 256 static void path_unwatch(Path *p) {
 257         PathSpec *s;
 258
 259         assert(p);
 260
 261         LIST_FOREACH(spec, s, p->specs)
 262                 path_unwatch_one(p, s);
 263 }
 264
 265 static int path_watch(Path *p) {
 266         int r;
 267         PathSpec *s;
 268
 269         assert(p);
 270
 271         LIST_FOREACH(spec, s, p->specs)
 272                 if ((r = path_watch_one(p, s)) < 0)
 273                         return r;
 274
 275         return 0;
 276 }
 277
 278 static void path_set_state(Path *p, PathState state) {
 279         PathState old_state;
 280         assert(p);
 281
 282         old_state = p->state;
 283         p->state = state;
 284
 285         if (state != PATH_WAITING &&
 286             (state != PATH_RUNNING || p->inotify_triggered))
 287                 path_unwatch(p);
 288
 289         if (state != old_state)
 290                 log_debug("%s changed %s -> %s",
 291                           p->meta.id,
 292                           path_state_to_string(old_state),
 293                           path_state_to_string(state));
 294
 295         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state], true);
 296 }
 297
 298 static void path_enter_waiting(Path *p, bool initial, bool recheck);
 299
 300 static int path_coldplug(Unit *u) {
 301         Path *p = PATH(u);
 302
 303         assert(p);
 304         assert(p->state == PATH_DEAD);
 305
 306         if (p->deserialized_state != p->state) {
 307
 308                 if (p->deserialized_state == PATH_WAITING ||
 309                     p->deserialized_state == PATH_RUNNING)
 310                         path_enter_waiting(p, true, true);
 311                 else
 312                         path_set_state(p, p->deserialized_state);
 313         }
 314
 315         return 0;
 316 }
 317
 318 static void path_enter_dead(Path *p, bool success) {
 319         assert(p);
 320
 321         if (!success)
 322                 p->failure = true;
 323
 324         path_set_state(p, p->failure ? PATH_FAILED : PATH_DEAD);
 325 }
 326
 327 static void path_enter_running(Path *p) {
 328         int r;
 329         DBusError error;
 330
 331         assert(p);
 332         dbus_error_init(&error);
 333
 334         /* Don't start job if we are supposed to go down */
 335         if (p->meta.job && p->meta.job->type == JOB_STOP)
 336                 return;
 337
 338         if ((r = manager_add_job(p->meta.manager, JOB_START, p->unit, JOB_REPLACE, true, &error, NULL)) < 0)
 339                 goto fail;
 340
 341         p->inotify_triggered = false;
 342
 343         if ((r = path_watch(p)) < 0)
 344                 goto fail;
 345
 346         path_set_state(p, PATH_RUNNING);
 347         return;
 348
 349 fail:
 350         log_warning("%s failed to queue unit startup job: %s", p->meta.id, bus_error(&error, r));
 351         path_enter_dead(p, false);
 352
 353         dbus_error_free(&error);
 354 }
 355
 356 static bool path_check_good(Path *p, bool initial) {
 357         PathSpec *s;
 358         bool good = false;
 359
 360         assert(p);
 361
 362         LIST_FOREACH(spec, s, p->specs) {
 363
 364                 switch (s->type) {
 365
 366                 case PATH_EXISTS:
 367                         good = access(s->path, F_OK) >= 0;
 368                         break;
 369
 370                 case PATH_DIRECTORY_NOT_EMPTY: {
 371                         int k;
 372
 373                         k = dir_is_empty(s->path);
 374                         good = !(k == -ENOENT || k > 0);
 375                         break;
 376                 }
 377
 378                 case PATH_CHANGED: {
 379                         bool b;
 380
 381                         b = access(s->path, F_OK) >= 0;
 382                         good = !initial && b != s->previous_exists;
 383                         s->previous_exists = b;
 384                         break;
 385                 }
 386
 387                 default:
 388                         ;
 389                 }
 390
 391                 if (good)
 392                         break;
 393         }
 394
 395         return good;
 396 }
 397
 398 static void path_enter_waiting(Path *p, bool initial, bool recheck) {
 399         int r;
 400
 401         if (recheck)
 402                 if (path_check_good(p, initial)) {
 403                         log_debug("%s got triggered.", p->meta.id);
 404                         path_enter_running(p);
 405                         return;
 406                 }
 407
 408         if ((r = path_watch(p)) < 0)
 409                 goto fail;
 410
 411         /* Hmm, so now we have created inotify watches, but the file
 412          * might have appeared/been removed by now, so we must
 413          * recheck */
 414
 415         if (recheck)
 416                 if (path_check_good(p, false)) {
 417                         log_debug("%s got triggered.", p->meta.id);
 418                         path_enter_running(p);
 419                         return;
 420                 }
 421
 422         path_set_state(p, PATH_WAITING);
 423         return;
 424
 425 fail:
 426         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 427         path_enter_dead(p, false);
 428 }
 429
 430 static void path_mkdir(Path *p) {
 431         PathSpec *s;
 432
 433         assert(p);
 434
 435         if (!p->make_directory)
 436                 return;
 437
 438         LIST_FOREACH(spec, s, p->specs) {
 439                 int r;
 440
 441                 if (s->type == PATH_EXISTS)
 442                         continue;
 443
 444                 if ((r = mkdir_p(s->path, p->directory_mode)) < 0)
 445                         log_warning("mkdir(%s) failed: %s", s->path, strerror(-r));
 446         }
 447 }
 448
 449 static int path_start(Unit *u) {
 450         Path *p = PATH(u);
 451
 452         assert(p);
 453         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 454
 455         if (p->unit->meta.load_state != UNIT_LOADED)
 456                 return -ENOENT;
 457
 458         path_mkdir(p);
 459
 460         p->failure = false;
 461         path_enter_waiting(p, true, true);
 462
 463         return 0;
 464 }
 465
 466 static int path_stop(Unit *u) {
 467         Path *p = PATH(u);
 468
 469         assert(p);
 470         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 471
 472         path_enter_dead(p, true);
 473         return 0;
 474 }
 475
 476 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 477         Path *p = PATH(u);
 478
 479         assert(u);
 480         assert(f);
 481         assert(fds);
 482
 483         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 484
 485         return 0;
 486 }
 487
 488 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 489         Path *p = PATH(u);
 490
 491         assert(u);
 492         assert(key);
 493         assert(value);
 494         assert(fds);
 495
 496         if (streq(key, "state")) {
 497                 PathState state;
 498
 499                 if ((state = path_state_from_string(value)) < 0)
 500                         log_debug("Failed to parse state value %s", value);
 501                 else
 502                         p->deserialized_state = state;
 503         } else
 504                 log_debug("Unknown serialization key '%s'", key);
 505
 506         return 0;
 507 }
 508
 509 static UnitActiveState path_active_state(Unit *u) {
 510         assert(u);
 511
 512         return state_translation_table[PATH(u)->state];
 513 }
 514
 515 static const char *path_sub_state_to_string(Unit *u) {
 516         assert(u);
 517
 518         return path_state_to_string(PATH(u)->state);
 519 }
 520
 521 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 522         Path *p = PATH(u);
 523         int l;
 524         ssize_t k;
 525         uint8_t *buf = NULL;
 526         struct inotify_event *e;
 527         PathSpec *s;
 528         bool changed;
 529
 530         assert(p);
 531         assert(fd >= 0);
 532
 533         if (p->state != PATH_WAITING &&
 534             p->state != PATH_RUNNING)
 535                 return;
 536
 537         /* log_debug("inotify wakeup on %s.", u->meta.id); */
 538
 539         if (events != EPOLLIN) {
 540                 log_error("Got Invalid poll event on inotify.");
 541                 goto fail;
 542         }
 543
 544         LIST_FOREACH(spec, s, p->specs)
 545                 if (s->inotify_fd == fd)
 546                         break;
 547
 548         if (!s) {
 549                 log_error("Got event on unknown fd.");
 550                 goto fail;
 551         }
 552
 553         if (ioctl(fd, FIONREAD, &l) < 0) {
 554                 log_error("FIONREAD failed: %s", strerror(errno));
 555                 goto fail;
 556         }
 557
 558         assert(l > 0);
 559
 560         if (!(buf = malloc(l))) {
 561                 log_error("Failed to allocate buffer: %s", strerror(-ENOMEM));
 562                 goto fail;
 563         }
 564
 565         if ((k = read(fd, buf, l)) < 0) {
 566                 log_error("Failed to read inotify event: %s", strerror(-errno));
 567                 goto fail;
 568         }
 569
 570         /* If we are already running, then remember that one event was
 571          * dispatched so that we restart the service only if something
 572          * actually changed on disk */
 573         p->inotify_triggered = true;
 574
 575         e = (struct inotify_event*) buf;
 576
 577         changed = false;
 578         while (k > 0) {
 579                 size_t step;
 580
 581                 if (s->type == PATH_CHANGED && s->primary_wd == e->wd)
 582                         changed = true;
 583
 584                 step = sizeof(struct inotify_event) + e->len;
 585                 assert(step <= (size_t) k);
 586
 587                 e = (struct inotify_event*) ((uint8_t*) e + step);
 588                 k -= step;
 589         }
 590
 591         if (changed)
 592                 path_enter_running(p);
 593         else
 594                 path_enter_waiting(p, false, true);
 595
 596         free(buf);
 597
 598         return;
 599
 600 fail:
 601         free(buf);
 602         path_enter_dead(p, false);
 603 }
 604
 605 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 606         char *n;
 607         int r;
 608         Iterator i;
 609
 610         if (u->meta.type == UNIT_PATH)
 611                 return;
 612
 613         SET_FOREACH(n, u->meta.names, i) {
 614                 char *k;
 615                 Unit *t;
 616                 Path *p;
 617
 618                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 619                         r = -ENOMEM;
 620                         goto fail;
 621                 }
 622
 623                 t = manager_get_unit(u->meta.manager, k);
 624                 free(k);
 625
 626                 if (!t)
 627                         continue;
 628
 629                 if (t->meta.load_state != UNIT_LOADED)
 630                         continue;
 631
 632                 p = PATH(t);
 633
 634                 if (p->unit != u)
 635                         continue;
 636
 637                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 638                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 639
 640                         /* Hmm, so inotify was triggered since the
 641                          * last activation, so I guess we need to
 642                          * recheck what is going on. */
 643                         path_enter_waiting(p, false, p->inotify_triggered);
 644                 }
 645         }
 646
 647         return;
 648
 649 fail:
 650         log_error("Failed find path unit: %s", strerror(-r));
 651 }
 652
 653 static void path_reset_failed(Unit *u) {
 654         Path *p = PATH(u);
 655
 656         assert(p);
 657
 658         if (p->state == PATH_FAILED)
 659                 path_set_state(p, PATH_DEAD);
 660
 661         p->failure = false;
 662 }
 663
 664 static const char* const path_state_table[_PATH_STATE_MAX] = {
 665         [PATH_DEAD] = "dead",
 666         [PATH_WAITING] = "waiting",
 667         [PATH_RUNNING] = "running",
 668         [PATH_FAILED] = "failed"
 669 };
 670
 671 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 672
 673 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 674         [PATH_EXISTS] = "PathExists",
 675         [PATH_CHANGED] = "PathChanged",
 676         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 677 };
 678
 679 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 680
 681 const UnitVTable path_vtable = {
 682         .suffix = ".path",
 683
 684         .init = path_init,
 685         .done = path_done,
 686         .load = path_load,
 687
 688         .coldplug = path_coldplug,
 689
 690         .dump = path_dump,
 691
 692         .start = path_start,
 693         .stop = path_stop,
 694
 695         .serialize = path_serialize,
 696         .deserialize_item = path_deserialize_item,
 697
 698         .active_state = path_active_state,
 699         .sub_state_to_string = path_sub_state_to_string,
 700
 701         .fd_event = path_fd_event,
 702
 703         .reset_failed = path_reset_failed,
 704
 705         .bus_interface = "org.freedesktop.systemd1.Path",
 706         .bus_message_handler = bus_path_message_handler
 707 };