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_per_type, other, p->meta.manager->units_per_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, bool skip_watch);
 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, false);
 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
 357 static void path_enter_waiting(Path *p, bool initial, bool recheck, bool skip_watch) {
 358         PathSpec *s;
 359         int r;
 360         bool good = false;
 361
 362         if (!recheck)
 363                 goto waiting;
 364
 365         LIST_FOREACH(spec, s, p->specs) {
 366
 367                 switch (s->type) {
 368
 369                 case PATH_EXISTS:
 370                         good = access(s->path, F_OK) >= 0;
 371                         break;
 372
 373                 case PATH_DIRECTORY_NOT_EMPTY: {
 374                         int k;
 375
 376                         k = dir_is_empty(s->path);
 377                         good = !(k == -ENOENT || k > 0);
 378                         break;
 379                 }
 380
 381                 case PATH_CHANGED: {
 382                         bool b;
 383
 384                         b = access(s->path, F_OK) >= 0;
 385                         good = !initial && b != s->previous_exists;
 386                         s->previous_exists = b;
 387                         break;
 388                 }
 389
 390                 default:
 391                         ;
 392                 }
 393
 394                 if (good)
 395                         break;
 396         }
 397
 398         if (good) {
 399                 log_debug("%s got triggered.", p->meta.id);
 400                 path_enter_running(p);
 401                 return;
 402         }
 403
 404 waiting:
 405         if (!skip_watch) {
 406                 if ((r = path_watch(p)) < 0)
 407                         goto fail;
 408
 409                 /* Hmm, so now we have created inotify watches, but the file
 410                  * might have appeared/been removed by now, so we must
 411                  * recheck */
 412                 path_enter_waiting(p, false, true, true);
 413                 return;
 414         }
 415
 416         path_set_state(p, PATH_WAITING);
 417         return;
 418
 419 fail:
 420         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 421         path_enter_dead(p, false);
 422 }
 423
 424 static void path_mkdir(Path *p) {
 425         PathSpec *s;
 426
 427         assert(p);
 428
 429         if (!p->make_directory)
 430                 return;
 431
 432         LIST_FOREACH(spec, s, p->specs) {
 433                 int r;
 434
 435                 if (s->type == PATH_EXISTS)
 436                         continue;
 437
 438                 if ((r = mkdir_p(s->path, p->directory_mode)) < 0)
 439                         log_warning("mkdir(%s) failed: %s", s->path, strerror(-r));
 440         }
 441 }
 442
 443 static int path_start(Unit *u) {
 444         Path *p = PATH(u);
 445
 446         assert(p);
 447         assert(p->state == PATH_DEAD || p->state == PATH_FAILED);
 448
 449         if (p->unit->meta.load_state != UNIT_LOADED)
 450                 return -ENOENT;
 451
 452         path_mkdir(p);
 453
 454         p->failure = false;
 455         path_enter_waiting(p, true, true, false);
 456
 457         return 0;
 458 }
 459
 460 static int path_stop(Unit *u) {
 461         Path *p = PATH(u);
 462
 463         assert(p);
 464         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 465
 466         path_enter_dead(p, true);
 467         return 0;
 468 }
 469
 470 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 471         Path *p = PATH(u);
 472
 473         assert(u);
 474         assert(f);
 475         assert(fds);
 476
 477         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 478
 479         return 0;
 480 }
 481
 482 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 483         Path *p = PATH(u);
 484
 485         assert(u);
 486         assert(key);
 487         assert(value);
 488         assert(fds);
 489
 490         if (streq(key, "state")) {
 491                 PathState state;
 492
 493                 if ((state = path_state_from_string(value)) < 0)
 494                         log_debug("Failed to parse state value %s", value);
 495                 else
 496                         p->deserialized_state = state;
 497         } else
 498                 log_debug("Unknown serialization key '%s'", key);
 499
 500         return 0;
 501 }
 502
 503 static UnitActiveState path_active_state(Unit *u) {
 504         assert(u);
 505
 506         return state_translation_table[PATH(u)->state];
 507 }
 508
 509 static const char *path_sub_state_to_string(Unit *u) {
 510         assert(u);
 511
 512         return path_state_to_string(PATH(u)->state);
 513 }
 514
 515 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 516         Path *p = PATH(u);
 517         int l;
 518         ssize_t k;
 519         uint8_t *buf = NULL;
 520         struct inotify_event *e;
 521         PathSpec *s;
 522         bool changed;
 523
 524         assert(p);
 525         assert(fd >= 0);
 526
 527         if (p->state != PATH_WAITING &&
 528             p->state != PATH_RUNNING)
 529                 return;
 530
 531         /* log_debug("inotify wakeup on %s.", u->meta.id); */
 532
 533         if (events != EPOLLIN) {
 534                 log_error("Got Invalid poll event on inotify.");
 535                 goto fail;
 536         }
 537
 538         LIST_FOREACH(spec, s, p->specs)
 539                 if (s->inotify_fd == fd)
 540                         break;
 541
 542         if (!s) {
 543                 log_error("Got event on unknown fd.");
 544                 goto fail;
 545         }
 546
 547         if (ioctl(fd, FIONREAD, &l) < 0) {
 548                 log_error("FIONREAD failed: %s", strerror(errno));
 549                 goto fail;
 550         }
 551
 552         if (!(buf = malloc(l))) {
 553                 log_error("Failed to allocate buffer: %s", strerror(-ENOMEM));
 554                 goto fail;
 555         }
 556
 557         if ((k = read(fd, buf, l)) < 0) {
 558                 log_error("Failed to read inotify event: %s", strerror(-errno));
 559                 goto fail;
 560         }
 561
 562         /* If we are already running, then remember that one event was
 563          * dispatched so that we restart the service only if something
 564          * actually changed on disk */
 565         p->inotify_triggered = true;
 566
 567         e = (struct inotify_event*) buf;
 568
 569         changed = false;
 570         while (k > 0) {
 571                 size_t step;
 572
 573                 if (s->type == PATH_CHANGED && s->primary_wd == e->wd)
 574                         changed = true;
 575
 576                 step = sizeof(struct inotify_event) + e->len;
 577                 assert(step <= (size_t) k);
 578
 579                 e = (struct inotify_event*) ((uint8_t*) e + step);
 580                 k -= step;
 581         }
 582
 583         if (changed)
 584                 path_enter_running(p);
 585         else
 586                 path_enter_waiting(p, false, true, false);
 587
 588         free(buf);
 589
 590         return;
 591
 592 fail:
 593         free(buf);
 594         path_enter_dead(p, false);
 595 }
 596
 597 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 598         char *n;
 599         int r;
 600         Iterator i;
 601
 602         if (u->meta.type == UNIT_PATH)
 603                 return;
 604
 605         SET_FOREACH(n, u->meta.names, i) {
 606                 char *k;
 607                 Unit *t;
 608                 Path *p;
 609
 610                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 611                         r = -ENOMEM;
 612                         goto fail;
 613                 }
 614
 615                 t = manager_get_unit(u->meta.manager, k);
 616                 free(k);
 617
 618                 if (!t)
 619                         continue;
 620
 621                 if (t->meta.load_state != UNIT_LOADED)
 622                         continue;
 623
 624                 p = PATH(t);
 625
 626                 if (p->unit != u)
 627                         continue;
 628
 629                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 630                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 631
 632                         /* Hmm, so inotify was triggered since the
 633                          * last activation, so I guess we need to
 634                          * recheck what is going on. */
 635                         path_enter_waiting(p, false, p->inotify_triggered, false);
 636                 }
 637         }
 638
 639         return;
 640
 641 fail:
 642         log_error("Failed find path unit: %s", strerror(-r));
 643 }
 644
 645 static void path_reset_failed(Unit *u) {
 646         Path *p = PATH(u);
 647
 648         assert(p);
 649
 650         if (p->state == PATH_FAILED)
 651                 path_set_state(p, PATH_DEAD);
 652
 653         p->failure = false;
 654 }
 655
 656 static const char* const path_state_table[_PATH_STATE_MAX] = {
 657         [PATH_DEAD] = "dead",
 658         [PATH_WAITING] = "waiting",
 659         [PATH_RUNNING] = "running",
 660         [PATH_FAILED] = "failed"
 661 };
 662
 663 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 664
 665 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 666         [PATH_EXISTS] = "PathExists",
 667         [PATH_CHANGED] = "PathChanged",
 668         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 669 };
 670
 671 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 672
 673 const UnitVTable path_vtable = {
 674         .suffix = ".path",
 675
 676         .init = path_init,
 677         .done = path_done,
 678         .load = path_load,
 679
 680         .coldplug = path_coldplug,
 681
 682         .dump = path_dump,
 683
 684         .start = path_start,
 685         .stop = path_stop,
 686
 687         .serialize = path_serialize,
 688         .deserialize_item = path_deserialize_item,
 689
 690         .active_state = path_active_state,
 691         .sub_state_to_string = path_sub_state_to_string,
 692
 693         .fd_event = path_fd_event,
 694
 695         .reset_failed = path_reset_failed,
 696
 697         .bus_interface = "org.freedesktop.systemd1.Path",
 698         .bus_message_handler = bus_path_message_handler
 699 };