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 #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_MAINTENANCE] = UNIT_MAINTENANCE
  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_load(Unit *u) {
 105         Path *p = PATH(u);
 106         int r;
 107
 108         assert(u);
 109         assert(u->meta.load_state == UNIT_STUB);
 110
 111         if ((r = unit_load_fragment_and_dropin(u)) < 0)
 112                 return r;
 113
 114         if (u->meta.load_state == UNIT_LOADED) {
 115
 116                 if (!p->unit)
 117                         if ((r = unit_load_related_unit(u, ".service", &p->unit)))
 118                                 return r;
 119
 120                 if ((r = unit_add_dependency(u, UNIT_BEFORE, p->unit, true)) < 0)
 121                         return r;
 122
 123                 if ((r = path_add_mount_links(p)) < 0)
 124                         return r;
 125
 126                 /* Path units shouldn't stay around on shutdown */
 127                 if (p->meta.default_dependencies)
 128                         if ((r = unit_add_two_dependencies_by_name(u, UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true)) < 0)
 129                                 return r;
 130         }
 131
 132         return path_verify(p);
 133 }
 134
 135 static void path_dump(Unit *u, FILE *f, const char *prefix) {
 136         Path *p = PATH(u);
 137         const char *prefix2;
 138         char *p2;
 139         PathSpec *s;
 140
 141         p2 = strappend(prefix, "\t");
 142         prefix2 = p2 ? p2 : prefix;
 143
 144         fprintf(f,
 145                 "%sPath State: %s\n"
 146                 "%sUnit: %s\n",
 147                 prefix, path_state_to_string(p->state),
 148                 prefix, p->unit->meta.id);
 149
 150         LIST_FOREACH(spec, s, p->specs)
 151                 fprintf(f,
 152                         "%s%s: %s\n",
 153                         prefix,
 154                         path_type_to_string(s->type),
 155                         s->path);
 156
 157         free(p2);
 158 }
 159
 160 static void path_unwatch_one(Path *p, PathSpec *s) {
 161
 162         if (s->inotify_fd < 0)
 163                 return;
 164
 165         unit_unwatch_fd(UNIT(p), &s->watch);
 166
 167         close_nointr_nofail(s->inotify_fd);
 168         s->inotify_fd = -1;
 169 }
 170
 171 static int path_watch_one(Path *p, PathSpec *s) {
 172         static const int flags_table[_PATH_TYPE_MAX] = {
 173                 [PATH_EXISTS] = IN_DELETE_SELF|IN_MOVE_SELF,
 174                 [PATH_CHANGED] = IN_DELETE_SELF|IN_MOVE_SELF|IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO,
 175                 [PATH_DIRECTORY_NOT_EMPTY] = IN_DELETE_SELF|IN_MOVE_SELF|IN_CREATE|IN_MOVED_TO
 176         };
 177
 178         bool exists = false;
 179         char *k;
 180         int r;
 181
 182         assert(p);
 183         assert(s);
 184
 185         path_unwatch_one(p, s);
 186
 187         if (!(k = strdup(s->path)))
 188                 return -ENOMEM;
 189
 190         if ((s->inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC)) < 0) {
 191                 r = -errno;
 192                 goto fail;
 193         }
 194
 195         if (unit_watch_fd(UNIT(p), s->inotify_fd, EPOLLIN, &s->watch) < 0) {
 196                 r = -errno;
 197                 goto fail;
 198         }
 199
 200         if ((s->primary_wd = inotify_add_watch(s->inotify_fd, k, flags_table[s->type])) >= 0)
 201                 exists = true;
 202
 203         for (;;) {
 204                 int flags;
 205                 char *slash;
 206
 207                 /* This assumes the path was passed through path_kill_slashes()! */
 208                 if (!(slash = strrchr(k, '/')))
 209                         break;
 210
 211                 *slash = 0;
 212
 213                 flags = IN_DELETE_SELF|IN_MOVE_SELF;
 214                 if (!exists)
 215                         flags |= IN_CREATE | IN_MOVED_TO | IN_ATTRIB;
 216
 217                 if (inotify_add_watch(s->inotify_fd, k, flags) >= 0)
 218                         exists = true;
 219         }
 220
 221         return 0;
 222
 223 fail:
 224         free(k);
 225
 226         path_unwatch_one(p, s);
 227         return r;
 228 }
 229
 230 static void path_unwatch(Path *p) {
 231         PathSpec *s;
 232
 233         assert(p);
 234
 235         LIST_FOREACH(spec, s, p->specs)
 236                 path_unwatch_one(p, s);
 237 }
 238
 239 static int path_watch(Path *p) {
 240         int r;
 241         PathSpec *s;
 242
 243         assert(p);
 244
 245         LIST_FOREACH(spec, s, p->specs)
 246                 if ((r = path_watch_one(p, s)) < 0)
 247                         return r;
 248
 249         return 0;
 250 }
 251
 252 static void path_set_state(Path *p, PathState state) {
 253         PathState old_state;
 254         assert(p);
 255
 256         old_state = p->state;
 257         p->state = state;
 258
 259         if (state != PATH_WAITING)
 260                 path_unwatch(p);
 261
 262         if (state != old_state)
 263                 log_debug("%s changed %s -> %s",
 264                           p->meta.id,
 265                           path_state_to_string(old_state),
 266                           path_state_to_string(state));
 267
 268         unit_notify(UNIT(p), state_translation_table[old_state], state_translation_table[state]);
 269 }
 270
 271 static void path_enter_waiting(Path *p, bool initial);
 272
 273 static int path_coldplug(Unit *u) {
 274         Path *p = PATH(u);
 275
 276         assert(p);
 277         assert(p->state == PATH_DEAD);
 278
 279         if (p->deserialized_state != p->state) {
 280
 281                 if (p->deserialized_state == PATH_WAITING ||
 282                     p->deserialized_state == PATH_RUNNING)
 283                         path_enter_waiting(p, true);
 284                 else
 285                         path_set_state(p, p->deserialized_state);
 286         }
 287
 288         return 0;
 289 }
 290
 291 static void path_enter_dead(Path *p, bool success) {
 292         assert(p);
 293
 294         if (!success)
 295                 p->failure = true;
 296
 297         path_set_state(p, p->failure ? PATH_MAINTENANCE : PATH_DEAD);
 298 }
 299
 300 static void path_enter_running(Path *p) {
 301         int r;
 302         DBusError error;
 303
 304         assert(p);
 305         dbus_error_init(&error);
 306
 307         if ((r = manager_add_job(p->meta.manager, JOB_START, p->unit, JOB_REPLACE, true, &error, NULL)) < 0)
 308                 goto fail;
 309
 310         path_set_state(p, PATH_RUNNING);
 311         return;
 312
 313 fail:
 314         log_warning("%s failed to queue unit startup job: %s", p->meta.id, bus_error(&error, r));
 315         path_enter_dead(p, false);
 316
 317         dbus_error_free(&error);
 318 }
 319
 320
 321 static void path_enter_waiting(Path *p, bool initial) {
 322         PathSpec *s;
 323         int r;
 324         bool good = false;
 325
 326         LIST_FOREACH(spec, s, p->specs) {
 327
 328                 switch (s->type) {
 329
 330                 case PATH_EXISTS:
 331                         good = access(s->path, F_OK) >= 0;
 332                         break;
 333
 334                 case PATH_DIRECTORY_NOT_EMPTY:
 335                         good = dir_is_empty(s->path) == 0;
 336                         break;
 337
 338                 case PATH_CHANGED: {
 339                         bool b;
 340
 341                         b = access(s->path, F_OK) >= 0;
 342                         good = !initial && b != s->previous_exists;
 343                         s->previous_exists = b;
 344                         break;
 345                 }
 346
 347                 default:
 348                         ;
 349                 }
 350
 351                 if (good)
 352                         break;
 353         }
 354
 355         if (good) {
 356                 path_enter_running(p);
 357                 return;
 358         }
 359
 360         if ((r = path_watch(p)) < 0)
 361                 goto fail;
 362
 363         path_set_state(p, PATH_WAITING);
 364         return;
 365
 366 fail:
 367         log_warning("%s failed to enter waiting state: %s", p->meta.id, strerror(-r));
 368         path_enter_dead(p, false);
 369 }
 370
 371 static int path_start(Unit *u) {
 372         Path *p = PATH(u);
 373
 374         assert(p);
 375         assert(p->state == PATH_DEAD || p->state == PATH_MAINTENANCE);
 376
 377         if (p->unit->meta.load_state != UNIT_LOADED)
 378                 return -ENOENT;
 379
 380         p->failure = false;
 381 path_enter_waiting(p, true);
 382         return 0;
 383 }
 384
 385 static int path_stop(Unit *u) {
 386         Path *p = PATH(u);
 387
 388         assert(p);
 389         assert(p->state == PATH_WAITING || p->state == PATH_RUNNING);
 390
 391         path_enter_dead(p, true);
 392         return 0;
 393 }
 394
 395 static int path_serialize(Unit *u, FILE *f, FDSet *fds) {
 396         Path *p = PATH(u);
 397
 398         assert(u);
 399         assert(f);
 400         assert(fds);
 401
 402         unit_serialize_item(u, f, "state", path_state_to_string(p->state));
 403
 404         return 0;
 405 }
 406
 407 static int path_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 408         Path *p = PATH(u);
 409
 410         assert(u);
 411         assert(key);
 412         assert(value);
 413         assert(fds);
 414
 415         if (streq(key, "state")) {
 416                 PathState state;
 417
 418                 if ((state = path_state_from_string(value)) < 0)
 419                         log_debug("Failed to parse state value %s", value);
 420                 else
 421                         p->deserialized_state = state;
 422         } else
 423                 log_debug("Unknown serialization key '%s'", key);
 424
 425         return 0;
 426 }
 427
 428 static UnitActiveState path_active_state(Unit *u) {
 429         assert(u);
 430
 431         return state_translation_table[PATH(u)->state];
 432 }
 433
 434 static const char *path_sub_state_to_string(Unit *u) {
 435         assert(u);
 436
 437         return path_state_to_string(PATH(u)->state);
 438 }
 439
 440 static void path_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
 441         Path *p = PATH(u);
 442         int l;
 443         ssize_t k;
 444         struct inotify_event *buf = NULL;
 445         PathSpec *s;
 446
 447         assert(p);
 448         assert(fd >= 0);
 449
 450         if (p->state != PATH_WAITING)
 451                 return;
 452
 453         log_debug("inotify wakeup on %s.", u->meta.id);
 454
 455         if (events != EPOLLIN) {
 456                 log_error("Got Invalid poll event on inotify.");
 457                 goto fail;
 458         }
 459
 460         LIST_FOREACH(spec, s, p->specs)
 461                 if (s->inotify_fd == fd)
 462                         break;
 463
 464         if (!s) {
 465                 log_error("Got event on unknown fd.");
 466                 goto fail;
 467         }
 468
 469         if (ioctl(fd, FIONREAD, &l) < 0) {
 470                 log_error("FIONREAD failed: %s", strerror(errno));
 471                 goto fail;
 472         }
 473
 474         if (!(buf = malloc(l))) {
 475                 log_error("Failed to allocate buffer: %s", strerror(-ENOMEM));
 476                 goto fail;
 477         }
 478
 479         if ((k = read(fd, buf, l)) < 0) {
 480                 log_error("Failed to read inotify event: %s", strerror(-errno));
 481                 goto fail;
 482         }
 483
 484         if ((size_t) k < sizeof(struct inotify_event) ||
 485             (size_t) k < sizeof(struct inotify_event) + buf->len) {
 486                 log_error("inotify event too small.");
 487                 goto fail;
 488         }
 489
 490         if (s->type == PATH_CHANGED && s->primary_wd == buf->wd)
 491                 path_enter_running(p);
 492         else
 493                 path_enter_waiting(p, false);
 494
 495         free(buf);
 496
 497         return;
 498
 499 fail:
 500         free(buf);
 501         path_enter_dead(p, false);
 502 }
 503
 504 void path_unit_notify(Unit *u, UnitActiveState new_state) {
 505         char *n;
 506         int r;
 507         Iterator i;
 508
 509         if (u->meta.type == UNIT_PATH)
 510                 return;
 511
 512         SET_FOREACH(n, u->meta.names, i) {
 513                 char *k;
 514                 Unit *t;
 515                 Path *p;
 516
 517                 if (!(k = unit_name_change_suffix(n, ".path"))) {
 518                         r = -ENOMEM;
 519                         goto fail;
 520                 }
 521
 522                 t = manager_get_unit(u->meta.manager, k);
 523                 free(k);
 524
 525                 if (!t)
 526                         continue;
 527
 528                 if (t->meta.load_state != UNIT_LOADED)
 529                         continue;
 530
 531                 p = PATH(t);
 532
 533                 if (p->unit != u)
 534                         continue;
 535
 536                 if (p->state == PATH_RUNNING && new_state == UNIT_INACTIVE) {
 537                         log_debug("%s got notified about unit deactivation.", p->meta.id);
 538                         path_enter_waiting(p, false);
 539                 }
 540         }
 541
 542         return;
 543
 544 fail:
 545         log_error("Failed find path unit: %s", strerror(-r));
 546 }
 547
 548 static const char* const path_state_table[_PATH_STATE_MAX] = {
 549         [PATH_DEAD] = "dead",
 550         [PATH_WAITING] = "waiting",
 551         [PATH_RUNNING] = "running",
 552         [PATH_MAINTENANCE] = "maintenance"
 553 };
 554
 555 DEFINE_STRING_TABLE_LOOKUP(path_state, PathState);
 556
 557 static const char* const path_type_table[_PATH_TYPE_MAX] = {
 558         [PATH_EXISTS] = "PathExists",
 559         [PATH_CHANGED] = "PathChanged",
 560         [PATH_DIRECTORY_NOT_EMPTY] = "DirectoryNotEmpty"
 561 };
 562
 563 DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
 564
 565 const UnitVTable path_vtable = {
 566         .suffix = ".path",
 567
 568         .done = path_done,
 569         .load = path_load,
 570
 571         .coldplug = path_coldplug,
 572
 573         .dump = path_dump,
 574
 575         .start = path_start,
 576         .stop = path_stop,
 577
 578         .serialize = path_serialize,
 579         .deserialize_item = path_deserialize_item,
 580
 581         .active_state = path_active_state,
 582         .sub_state_to_string = path_sub_state_to_string,
 583
 584         .fd_event = path_fd_event,
 585
 586         .bus_message_handler = bus_path_message_handler
 587 };