src/path.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   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
  34 static const UnitActiveState state_translation_table[_PATH_STATE_MAX] = {
  35         [PATH_DEAD] = UNIT_INACTIVE,
  36         [PATH_WAITING] = UNIT_ACTIVE,
  37         [PATH_RUNNING] = UNIT_ACTIVE,
  38         [PATH_MAINTENANCE] = UNIT_MAINTENANCE
  39 };
  40
  41 static void path_done(Unit *u) {
  42         Path *p = PATH(u);
  43         PathSpec *s;
  44
  45         assert(p);
  46
  47         while ((s = p->specs)) {
  48                 LIST_REMOVE(PathSpec, spec, p->specs, s);
  49                 free(s);
  50         }
  51 }
  52
  53 int path_add_one_mount_link(Path *p, Mount *m) {
  54         PathSpec *s;
  55         int r;
  56
  57         assert(p);
  58         assert(m);
  59
  60         if (p->meta.load_state != UNIT_LOADED ||
  61             m->meta.load_state != UNIT_LOADED)
  62                 return 0;
  63
  64         LIST_FOREACH(spec, s, p->specs) {
  65
  66                 if (!path_startswith(s->path, m->where))
  67                         continue;
  68
  69                 if ((r = unit_add_two_dependencies(UNIT(p), UNIT_AFTER, UNIT_REQUIRES, UNIT(m), true)) < 0)
  70                         return r;
  71         }
  72
  73         return 0;
  74 }
  75
  76 static int path_add_mount_links(Path *p) {
  77         Meta *other;
  78         int r;
  79
  80         assert(p);
  81
  82         LIST_FOREACH(units_per_type, other, p->meta.manager->units_per_type[UNIT_MOUNT])
  83                 if ((r = path_add_one_mount_link(p, (Mount*) other)) < 0)
  84                         return r;
  85
  86         return 0;
  87 }
  88
  89 static int path_verify(Path *p) {
  90         assert(p);
  91
  92         if (p->meta.load_state != UNIT_LOADED)
  93                 return 0;
  94
  95         if (!p->specs) {
  96                 log_error("%s lacks path setting. Refusing.", p->meta.id);
  97                 return -EINVAL;
  98         }
  99
 100         return 0;
 101 }
 102
 103 static int path_load(Unit *u) {
 104         Path *p = PATH(u);
 105         int r;
 106
 107         assert(u);
 108         assert(u->meta.load_state == UNIT_STUB);
 109
 110         if ((r = unit_load_fragment_and_dropin(u)) < 0)
 111                 return r;
 112
 113         if (u->meta.load_state == UNIT_LOADED) {
 114
 115                 if (!p->unit)
 116                         if ((r = unit_load_related_unit(u, ".service", &p->unit)))
 117                                 return r;
 118
 119                 if ((r = unit_add_dependency(u, UNIT_BEFORE, p->unit, true)) < 0)
 120                         return r;
 121
 122                 if ((r = path_add_mount_links(p)) < 0)
 123                         return r;
 124
 125                 /* Path units shouldn't stay around on shutdown */
 126                 if (p->meta.default_dependencies)
 127                         if ((r = unit_add_two_dependencies_by_name(u, UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true)) < 0)
 128                                 return r;
 129         }
 130
 131         return path_verify(p);
 132 }
 133
 134 static void path_dump(Unit *u, FILE *f, const char *prefix) {
 135         Path *p = PATH(u);
 136         const char *prefix2;
 137         char *p2;
 138         PathSpec *s;
 139
 140         p2 = strappend(prefix, "\t");
 141         prefix2 = p2 ? p2 : prefix;
 142
 143         fprintf(f,
 144                 "%sPath State: %s\n"
 145                 "%sUnit: %s\n",
 146                 prefix, path_state_to_string(p->state),
 147                 prefix, p->unit->meta.id);
 148
 149         LIST_FOREACH(spec, s, p->specs)
 150                 fprintf(f,
 151                         "%s%s: %s\n",
 152                         prefix,
 153                         path_type_to_string(s->type),
 154                         s->path);
 155
 156         free(p2);
 157 }
 158
 159 static void path_unwatch_one(Path *p, PathSpec *s) {
 160
 161         if (s->inotify_fd < 0)
 162                 return;
 163
 164         unit_unwatch_fd(UNIT(p), &s->watch);
 165
 166         close_nointr_nofail(s->inotify_fd);
 167         s->inotify_fd = -1;
 168 }
 169
 170 static int path_watch_one(Path *p, PathSpec *s) {
 171         static const int flags_table[_PATH_TYPE_MAX] = {
 172                 [PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF,
 173                 [PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
 174                 [PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_CREATE|IN_MOVED_TO
 175         };
 176
 177         bool exists = false;
 178         char *k;
 179         int r;
 180
 181         assert(p);
 182         assert(s);
 183
 184         path_unwatch_one(p, s);
 185
 186         if (!(k = strdup(s->path)))
 187                 return -ENOMEM;
 188
 189         if ((s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC)) < 0) {
 190                 r = -errno;
 191                 goto fail;
 192         }
 193
 194         if (unit_watch_fd(UNIT(p), s->inotify_fd, EPOLLIN, &s->watch) < 0) {
 195                 r = -errno;
 196                 goto fail;
 197         }
 198
 199         if ((s->primary_wd = inotify_add_watch(s->inotify_fd, k, flags_table[s->type])) >= 0)
 200                 exists = true;
 201
 202         for (;;) {
 203                 int flags;
 204                 char *slash;
 205
 206                 /* This assumes the path was passed through path_kill_slashes()! */
 207                 if (!(slash = strrchr(k, '/')))
 208                         break;
 209
 210                 *slash = 0;
 211
 212                 flags = IN_DELETE_SELF|IN_MOVE_SELF;
 213                 if (!exists)
 214                         flags |= IN_CREATE | IN_MOVED_TO | IN_ATTRIB;
 215
 216                 if (inotify_add_watch(s->inotify_fd, k, flags) >= 0)
 217                         exists = true;
 218         }
 219
 220         return 0;
 221
 222 fail:
 223         free(k);
 224
 225         path_unwatch_one(p, s);
 226         return r;
 227 }
 228
 229 static void path_unwatch(Path *p) {
 230         PathSpec *s;
 231
 232         assert(p);
 233
 234         LIST_FOREACH(spec, s, p->specs)
 235                 path_unwatch_one(p, s);
 236 }
 237
 238 static int path_watch(Path *p) {
 239         int r;
 240         PathSpec *s;
 241
 242         assert(p);
 243
 244         LIST_FOREACH(spec, s, p->specs)
 245                 if ((r = path_watch_one(p, s)) < 0)
 246                         return r;
 247
 248         return 0;
 249 }
 250
 251 static void path_set_state(Path *p, PathState state) {
 252         PathState old_state;
 253         assert(p);
 254
 255         old_state = p->state;
 256         p->state = state;
 257
 258         if (state != PATH_WAITING)
 259                 path_unwatch(p);
 260
 261         if (state != old_state)
 262                 log_debug("%s changed %s -> %s",
 263                           p->meta.id,
 264                           path_state_to_string(old_state),
 265                           path_state_to_string(state));
 266
 267         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state]);
 268 }
 269
 270 static void path_enter_waiting(Path *p, bool initial);
 271
 272 static int path_coldplug(Unit *u) {
 273         Path *p = PATH(u);
 274
 275         assert(p);
 276         assert(p->state == PATH_DEAD);
 277
 278         if (p->deserialized_state != p->state) {
 279
 280                 if (p->deserialized_state == PATH_WAITING ||
 281                     p->deserialized_state == PATH_RUNNING)
 282                         path_enter_waiting(p, true);
 283                 else
 284                         path_set_state(p, p->deserialized_state);
 285         }
 286
 287         return 0;
 288 }
 289
 290 static void path_enter_dead(Path *p, bool success) {
 291         assert(p);
 292
 293         if (!success)
 294                 p->failure = true;
 295
 296         path_set_state(p, p->failure ? PATH_MAINTENANCE : PATH_DEAD);
 297 }
 298
 299 static void path_enter_running(Path *p) {
 300         int r;
 301         assert(p);
 302
 303         if ((r = manager_add_job(p->meta.manager, JOB_START, p->unit, JOB_REPLACE, true, NULL)) < 0)
 304                 goto fail;
 305
 306         path_set_state(p, PATH_RUNNING);
 307         return;
 308
 309 fail:
 310         log_warning("%s failed to queue unit startup job: %s", p->meta.id, strerror(-r));
 311         path_enter_dead(p, false);
 312 }
 313
 314
 315 static void path_enter_waiting(Path *p, bool initial) {
 316         PathSpec *s;
 317         int r;
 318         bool good = false;
 319
 320         LIST_FOREACH(spec, s, p->specs) {
 321
 322                 switch (s->type) {
 323
 324                 case PATH_EXISTS:
 325                         good = access(s->path, F_OK) >= 0;
 326                         break;
 327
 328                 case PATH_DIRECTORY_NOT_EMPTY:
 329                         good = dir_is_empty(s->path) == 0;
 330                         break;
 331
 332                 case PATH_CHANGED: {
 333                         bool b;
 334
 335                         b = access(s->path, F_OK) >= 0;
 336                         good = !initial && b != s->previous_exists;
 337                         s->previous_exists = b;
 338                         break;
 339                 }
 340
 341                 default:
 342                         ;
 343                 }
 344
 345                 if (good)
 346                         break;
 347         }
 348
 349         if (good) {
 350                 path_enter_running(p);
 351                 return;
 352         }
 353
 354         if ((r = path_watch(p)) < 0)
 355                 goto fail;
 356
 357         path_set_state(p, PATH_WAITING);
 358         return;
 359
 360 fail:
 361         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 362         path_enter_dead(p, false);
 363 }
 364
 365 static int path_start(Unit *u) {
 366         Path *p = PATH(u);
 367
 368         assert(p);
 369         assert(p->state == PATH_DEAD || p->state == PATH_MAINTENANCE);
 370
 371         if (p->unit->meta.load_state != UNIT_LOADED)
 372                 return -ENOENT;
 373
 374         p->failure = false;
 375 path_enter_waiting(p, true);
 376         return 0;
 377 }
 378
 379 static int path_stop(Unit *u) {
 380         Path *p = PATH(u);
 381
 382         assert(p);
 383         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 384
 385         path_enter_dead(p, true);
 386         return 0;
 387 }
 388
 389 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 390         Path *p = PATH(u);
 391
 392         assert(u);
 393         assert(f);
 394         assert(fds);
 395
 396         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 397
 398         return 0;
 399 }
 400
 401 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 402         Path *p = PATH(u);
 403
 404         assert(u);
 405         assert(key);
 406         assert(value);
 407         assert(fds);
 408
 409         if (streq(key, "state")) {
 410                 PathState state;
 411
 412                 if ((state = path_state_from_string(value)) < 0)
 413                         log_debug("Failed to parse state value %s", value);
 414                 else
 415                         p->deserialized_state = state;
 416         } else
 417                 log_debug("Unknown serialization key '%s'", key);
 418
 419         return 0;
 420 }
 421
 422 static UnitActiveState path_active_state(Unit *u) {
 423         assert(u);
 424
 425         return state_translation_table[PATH(u)->state];
 426 }
 427
 428 static const char *path_sub_state_to_string(Unit *u) {
 429         assert(u);
 430
 431         return path_state_to_string(PATH(u)->state);
 432 }
 433
 434 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 435         Path *p = PATH(u);
 436         int l;
 437         ssize_t k;
 438         struct inotify_event *buf = NULL;
 439         PathSpec *s;
 440
 441         assert(p);
 442         assert(fd >= 0);
 443
 444         if (p->state != PATH_WAITING)
 445                 return;
 446
 447         log_debug("inotify wakeup on %s.", u->meta.id);
 448
 449         if (events != EPOLLIN) {
 450                 log_error("Got Invalid poll event on inotify.");
 451                 goto fail;
 452         }
 453
 454         LIST_FOREACH(spec, s, p->specs)
 455                 if (s->inotify_fd == fd)
 456                         break;
 457
 458         if (!s) {
 459                 log_error("Got event on unknown fd.");
 460                 goto fail;
 461         }
 462
 463         if (ioctl(fd, FIONREAD, &l) < 0) {
 464                 log_error("FIONREAD failed: %s", strerror(errno));
 465                 goto fail;
 466         }
 467
 468         if (!(buf = malloc(l))) {
 469                 log_error("Failed to allocate buffer: %s", strerror(-ENOMEM));
 470                 goto fail;
 471         }
 472
 473         if ((k = read(fd, buf, l)) < 0) {
 474                 log_error("Failed to read inotify event: %s", strerror(-errno));
 475                 goto fail;
 476         }
 477
 478         if ((size_t) k < sizeof(struct inotify_event) ||
 479             (size_t) k < sizeof(struct inotify_event) + buf->len) {
 480                 log_error("inotify event too small.");
 481                 goto fail;
 482         }
 483
 484         if (s->type == PATH_CHANGED && s->primary_wd == buf->wd)
 485                 path_enter_running(p);
 486         else
 487                 path_enter_waiting(p, false);
 488
 489         free(buf);
 490
 491         return;
 492
 493 fail:
 494         free(buf);
 495         path_enter_dead(p, false);
 496 }
 497
 498 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 499         char *n;
 500         int r;
 501         Iterator i;
 502
 503         if (u->meta.type == UNIT_PATH)
 504                 return;
 505
 506         SET_FOREACH(n, u->meta.names, i) {
 507                 char *k;
 508                 Unit *t;
 509                 Path *p;
 510
 511                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 512                         r = -ENOMEM;
 513                         goto fail;
 514                 }
 515
 516                 t = manager_get_unit(u->meta.manager, k);
 517                 free(k);
 518
 519                 if (!t)
 520                         continue;
 521
 522                 if (t->meta.load_state != UNIT_LOADED)
 523                         continue;
 524
 525                 p = PATH(t);
 526
 527                 if (p->unit != u)
 528                         continue;
 529
 530                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 531                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 532                         path_enter_waiting(p, false);
 533                 }
 534         }
 535
 536         return;
 537
 538 fail:
 539         log_error("Failed find path unit: %s", strerror(-r));
 540 }
 541
 542 static const char* const path_state_table[_PATH_STATE_MAX] = {
 543         [PATH_DEAD] = "dead",
 544         [PATH_WAITING] = "waiting",
 545         [PATH_RUNNING] = "running",
 546         [PATH_MAINTENANCE] = "maintenance"
 547 };
 548
 549 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 550
 551 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 552         [PATH_EXISTS] = "PathExists",
 553         [PATH_CHANGED] = "PathChanged",
 554         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 555 };
 556
 557 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 558
 559 const UnitVTable path_vtable = {
 560         .suffix = ".path",
 561
 562         .done = path_done,
 563         .load = path_load,
 564
 565         .coldplug = path_coldplug,
 566
 567         .dump = path_dump,
 568
 569         .start = path_start,
 570         .stop = path_stop,
 571
 572         .serialize = path_serialize,
 573         .deserialize_item = path_deserialize_item,
 574
 575         .active_state = path_active_state,
 576         .sub_state_to_string = path_sub_state_to_string,
 577
 578         .fd_event = path_fd_event,
 579
 580         .bus_message_handler = bus_path_message_handler
 581 };