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