manager.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   2
   3 #include <assert.h>
   4 #include <errno.h>
   5 #include <string.h>
   6 #include <sys/epoll.h>
   7 #include <signal.h>
   8 #include <sys/signalfd.h>
   9 #include <sys/wait.h>
  10 #include <unistd.h>
  11 #include <sys/poll.h>
  12
  13 #include "manager.h"
  14 #include "hashmap.h"
  15 #include "macro.h"
  16 #include "strv.h"
  17 #include "log.h"
  18 #include "util.h"
  19
  20 static const char * const special_table[_SPECIAL_UNIT_MAX] = {
  21         [SPECIAL_SYSLOG_SERVICE] = "syslog.service",
  22         [SPECIAL_DBUS_SERVICE] = "messagebus.service",
  23         [SPECIAL_LOGGER_SOCKET] = "systemd-logger.socket",
  24         [SPECIAL_KBREQUEST_TARGET] = "kbrequest.target",
  25         [SPECIAL_CTRL_ALT_DEL_TARGET] = "ctrl-alt-del.target"
  26 };
  27
  28 static int manager_setup_signals(Manager *m) {
  29         sigset_t mask;
  30         struct epoll_event ev;
  31
  32         assert(m);
  33
  34         assert_se(reset_all_signal_handlers() == 0);
  35
  36         assert_se(sigemptyset(&mask) == 0);
  37         assert_se(sigaddset(&mask, SIGCHLD) == 0);
  38         assert_se(sigaddset(&mask, SIGINT) == 0);   /* Kernel sends us this on control-alt-del */
  39         assert_se(sigaddset(&mask, SIGWINCH) == 0); /* Kernel sends us this on kbrequest (alt-arrowup) */
  40         assert_se(sigaddset(&mask, SIGTERM) == 0);
  41         assert_se(sigaddset(&mask, SIGHUP) == 0);
  42         assert_se(sigaddset(&mask, SIGUSR1) == 0);
  43         assert_se(sigaddset(&mask, SIGUSR2) == 0);
  44         assert_se(sigaddset(&mask, SIGPIPE) == 0);
  45         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
  46
  47         m->signal_watch.type = WATCH_SIGNAL_FD;
  48         if ((m->signal_watch.fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0)
  49                 return -errno;
  50
  51         zero(ev);
  52         ev.events = EPOLLIN;
  53         ev.data.ptr = &m->signal_watch;
  54
  55         if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->signal_watch.fd, &ev) < 0)
  56                 return -errno;
  57
  58         return 0;
  59 }
  60
  61 static int manager_load_special_units(Manager *m) {
  62         SpecialUnit c;
  63         int r;
  64
  65         assert(m);
  66
  67         /* Loads all 'special' units, so that we have easy access to them later */
  68
  69         for (c = 0; c < _SPECIAL_UNIT_MAX; c++)
  70                 if ((r = manager_load_unit(m, special_table[c], m->special_units+c)) < 0)
  71                         return r;
  72
  73         return 0;
  74 };
  75
  76 Manager* manager_new(void) {
  77         Manager *m;
  78
  79         if (!(m = new0(Manager, 1)))
  80                 return NULL;
  81
  82         m->signal_watch.fd = m->epoll_fd = -1;
  83
  84         if (!(m->units = hashmap_new(string_hash_func, string_compare_func)))
  85                 goto fail;
  86
  87         if (!(m->jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
  88                 goto fail;
  89
  90         if (!(m->transaction_jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
  91                 goto fail;
  92
  93         if (!(m->watch_pids = hashmap_new(trivial_hash_func, trivial_compare_func)))
  94                 goto fail;
  95
  96         if ((m->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0)
  97                 goto fail;
  98
  99         if (manager_setup_signals(m) < 0)
 100                 goto fail;
 101
 102         if (manager_load_special_units(m) < 0)
 103                 goto fail;
 104
 105         return m;
 106
 107 fail:
 108         manager_free(m);
 109         return NULL;
 110 }
 111
 112 void manager_free(Manager *m) {
 113         Unit *u;
 114         Job *j;
 115
 116         assert(m);
 117
 118         while ((j = hashmap_first(m->transaction_jobs)))
 119                 job_free(j);
 120
 121         while ((u = hashmap_first(m->units)))
 122                 unit_free(u);
 123
 124         hashmap_free(m->units);
 125         hashmap_free(m->jobs);
 126         hashmap_free(m->transaction_jobs);
 127         hashmap_free(m->watch_pids);
 128
 129         if (m->epoll_fd >= 0)
 130                 close_nointr(m->epoll_fd);
 131         if (m->signal_watch.fd >= 0)
 132                 close_nointr(m->signal_watch.fd);
 133
 134         free(m);
 135 }
 136
 137 static void transaction_delete_job(Manager *m, Job *j) {
 138         assert(m);
 139         assert(j);
 140
 141         /* Deletes one job from the transaction */
 142
 143         manager_transaction_unlink_job(m, j);
 144
 145         if (!j->installed)
 146                 job_free(j);
 147 }
 148
 149 static void transaction_delete_unit(Manager *m, Unit *u) {
 150         Job *j;
 151
 152         /* Deletes all jobs associated with a certain unit from the
 153          * transaction */
 154
 155         while ((j = hashmap_get(m->transaction_jobs, u)))
 156                 transaction_delete_job(m, j);
 157 }
 158
 159 static void transaction_clean_dependencies(Manager *m) {
 160         Iterator i;
 161         Job *j;
 162
 163         assert(m);
 164
 165         /* Drops all dependencies of all installed jobs */
 166
 167         HASHMAP_FOREACH(j, m->jobs, i) {
 168                 while (j->subject_list)
 169                         job_dependency_free(j->subject_list);
 170                 while (j->object_list)
 171                         job_dependency_free(j->object_list);
 172         }
 173
 174         assert(!m->transaction_anchor);
 175 }
 176
 177 static void transaction_abort(Manager *m) {
 178         Job *j;
 179
 180         assert(m);
 181
 182         while ((j = hashmap_first(m->transaction_jobs)))
 183                 if (j->installed)
 184                         transaction_delete_job(m, j);
 185                 else
 186                         job_free(j);
 187
 188         assert(hashmap_isempty(m->transaction_jobs));
 189
 190         transaction_clean_dependencies(m);
 191 }
 192
 193 static void transaction_find_jobs_that_matter_to_anchor(Manager *m, Job *j, unsigned generation) {
 194         JobDependency *l;
 195
 196         assert(m);
 197
 198         /* A recursive sweep through the graph that marks all units
 199          * that matter to the anchor job, i.e. are directly or
 200          * indirectly a dependency of the anchor job via paths that
 201          * are fully marked as mattering. */
 202
 203         if (j)
 204                 l = j->subject_list;
 205         else
 206                 l = m->transaction_anchor;
 207
 208         LIST_FOREACH(subject, l, l) {
 209
 210                 /* This link does not matter */
 211                 if (!l->matters)
 212                         continue;
 213
 214                 /* This unit has already been marked */
 215                 if (l->object->generation == generation)
 216                         continue;
 217
 218                 l->object->matters_to_anchor = true;
 219                 l->object->generation = generation;
 220
 221                 transaction_find_jobs_that_matter_to_anchor(m, l->object, generation);
 222         }
 223 }
 224
 225 static void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, JobType t) {
 226         JobDependency *l, *last;
 227
 228         assert(j);
 229         assert(other);
 230         assert(j->unit == other->unit);
 231         assert(!j->installed);
 232
 233         /* Merges 'other' into 'j' and then deletes j. */
 234
 235         j->type = t;
 236         j->state = JOB_WAITING;
 237         j->forced = j->forced || other->forced;
 238
 239         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
 240
 241         /* Patch us in as new owner of the JobDependency objects */
 242         last = NULL;
 243         LIST_FOREACH(subject, l, other->subject_list) {
 244                 assert(l->subject == other);
 245                 l->subject = j;
 246                 last = l;
 247         }
 248
 249         /* Merge both lists */
 250         if (last) {
 251                 last->subject_next = j->subject_list;
 252                 if (j->subject_list)
 253                         j->subject_list->subject_prev = last;
 254                 j->subject_list = other->subject_list;
 255         }
 256
 257         /* Patch us in as new owner of the JobDependency objects */
 258         last = NULL;
 259         LIST_FOREACH(object, l, other->object_list) {
 260                 assert(l->object == other);
 261                 l->object = j;
 262                 last = l;
 263         }
 264
 265         /* Merge both lists */
 266         if (last) {
 267                 last->object_next = j->object_list;
 268                 if (j->object_list)
 269                         j->object_list->object_prev = last;
 270                 j->object_list = other->object_list;
 271         }
 272
 273         /* Kill the other job */
 274         other->subject_list = NULL;
 275         other->object_list = NULL;
 276         transaction_delete_job(m, other);
 277 }
 278
 279 static int delete_one_unmergeable_job(Manager *m, Job *j) {
 280         Job *k;
 281
 282         assert(j);
 283
 284         /* Tries to delete one item in the linked list
 285          * j->transaction_next->transaction_next->... that conflicts
 286          * whith another one, in an attempt to make an inconsistent
 287          * transaction work. */
 288
 289         /* We rely here on the fact that if a merged with b does not
 290          * merge with c, either a or b merge with c neither */
 291         LIST_FOREACH(transaction, j, j)
 292                 LIST_FOREACH(transaction, k, j->transaction_next) {
 293                         Job *d;
 294
 295                         /* Is this one mergeable? Then skip it */
 296                         if (job_type_is_mergeable(j->type, k->type))
 297                                 continue;
 298
 299                         /* Ok, we found two that conflict, let's see if we can
 300                          * drop one of them */
 301                         if (!j->matters_to_anchor)
 302                                 d = j;
 303                         else if (!k->matters_to_anchor)
 304                                 d = k;
 305                         else
 306                                 return -ENOEXEC;
 307
 308                         /* Ok, we can drop one, so let's do so. */
 309                         log_debug("Try to fix job merging by deleting job %s/%s", unit_id(d->unit), job_type_to_string(d->type));
 310                         transaction_delete_job(m, d);
 311                         return 0;
 312                 }
 313
 314         return -EINVAL;
 315 }
 316
 317 static int transaction_merge_jobs(Manager *m) {
 318         Job *j;
 319         Iterator i;
 320         int r;
 321
 322         assert(m);
 323
 324         /* First step, check whether any of the jobs for one specific
 325          * task conflict. If so, try to drop one of them. */
 326         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 327                 JobType t;
 328                 Job *k;
 329
 330                 t = j->type;
 331                 LIST_FOREACH(transaction, k, j->transaction_next) {
 332                         if ((r = job_type_merge(&t, k->type)) >= 0)
 333                                 continue;
 334
 335                         /* OK, we could not merge all jobs for this
 336                          * action. Let's see if we can get rid of one
 337                          * of them */
 338
 339                         if ((r = delete_one_unmergeable_job(m, j)) >= 0)
 340                                 /* Ok, we managed to drop one, now
 341                                  * let's ask our callers to call us
 342                                  * again after garbage collecting */
 343                                 return -EAGAIN;
 344
 345                         /* We couldn't merge anything. Failure */
 346                         return r;
 347                 }
 348         }
 349
 350         /* Second step, merge the jobs. */
 351         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 352                 JobType t = j->type;
 353                 Job *k;
 354
 355                 /* Merge all transactions */
 356                 LIST_FOREACH(transaction, k, j->transaction_next)
 357                         assert_se(job_type_merge(&t, k->type) == 0);
 358
 359                 /* If an active job is mergeable, merge it too */
 360                 if (j->unit->meta.job)
 361                         job_type_merge(&t, j->unit->meta.job->type); /* Might fail. Which is OK */
 362
 363                 while ((k = j->transaction_next)) {
 364                         if (j->installed) {
 365                                 transaction_merge_and_delete_job(m, k, j, t);
 366                                 j = k;
 367                         } else
 368                                 transaction_merge_and_delete_job(m, j, k, t);
 369                 }
 370
 371                 assert(!j->transaction_next);
 372                 assert(!j->transaction_prev);
 373         }
 374
 375         return 0;
 376 }
 377
 378 static bool unit_matters_to_anchor(Unit *u, Job *j) {
 379         assert(u);
 380         assert(!j->transaction_prev);
 381
 382         /* Checks whether at least one of the jobs for this unit
 383          * matters to the anchor. */
 384
 385         LIST_FOREACH(transaction, j, j)
 386                 if (j->matters_to_anchor)
 387                         return true;
 388
 389         return false;
 390 }
 391
 392 static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
 393         Iterator i;
 394         Unit *u;
 395         int r;
 396
 397         assert(m);
 398         assert(j);
 399         assert(!j->transaction_prev);
 400
 401         /* Does a recursive sweep through the ordering graph, looking
 402          * for a cycle. If we find cycle we try to break it. */
 403
 404         /* Did we find a cycle? */
 405         if (j->marker && j->generation == generation) {
 406                 Job *k;
 407
 408                 /* So, we already have been here. We have a
 409                  * cycle. Let's try to break it. We go backwards in
 410                  * our path and try to find a suitable job to
 411                  * remove. We use the marker to find our way back,
 412                  * since smart how we are we stored our way back in
 413                  * there. */
 414
 415                 for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
 416
 417                         if (!k->installed &&
 418                             !unit_matters_to_anchor(k->unit, k)) {
 419                                 /* Ok, we can drop this one, so let's
 420                                  * do so. */
 421                                 log_debug("Breaking order cycle by deleting job %s/%s", unit_id(k->unit), job_type_to_string(k->type));
 422                                 transaction_delete_unit(m, k->unit);
 423                                 return -EAGAIN;
 424                         }
 425
 426                         /* Check if this in fact was the beginning of
 427                          * the cycle */
 428                         if (k == j)
 429                                 break;
 430                 }
 431
 432                 return -ENOEXEC;
 433         }
 434
 435         /* Make the marker point to where we come from, so that we can
 436          * find our way backwards if we want to break a cycle */
 437         j->marker = from;
 438         j->generation = generation;
 439
 440         /* We assume that the the dependencies are bidirectional, and
 441          * hence can ignore UNIT_AFTER */
 442         SET_FOREACH(u, j->unit->meta.dependencies[UNIT_BEFORE], i) {
 443                 Job *o;
 444
 445                 /* Is there a job for this unit? */
 446                 if (!(o = hashmap_get(m->transaction_jobs, u)))
 447
 448                         /* Ok, there is no job for this in the
 449                          * transaction, but maybe there is already one
 450                          * running? */
 451                         if (!(o = u->meta.job))
 452                                 continue;
 453
 454                 if ((r = transaction_verify_order_one(m, o, j, generation)) < 0)
 455                         return r;
 456         }
 457
 458         return 0;
 459 }
 460
 461 static int transaction_verify_order(Manager *m, unsigned *generation) {
 462         Job *j;
 463         int r;
 464         Iterator i;
 465
 466         assert(m);
 467         assert(generation);
 468
 469         /* Check if the ordering graph is cyclic. If it is, try to fix
 470          * that up by dropping one of the jobs. */
 471
 472         HASHMAP_FOREACH(j, m->transaction_jobs, i)
 473                 if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
 474                         return r;
 475
 476         return 0;
 477 }
 478
 479 static void transaction_collect_garbage(Manager *m) {
 480         bool again;
 481
 482         assert(m);
 483
 484         /* Drop jobs that are not required by any other job */
 485
 486         do {
 487                 Iterator i;
 488                 Job *j;
 489
 490                 again = false;
 491
 492                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 493                         if (j->object_list)
 494                                 continue;
 495
 496                         log_debug("Garbage collecting job %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 497                         transaction_delete_job(m, j);
 498                         again = true;
 499                         break;
 500                 }
 501
 502         } while (again);
 503 }
 504
 505 static int transaction_is_destructive(Manager *m, JobMode mode) {
 506         Iterator i;
 507         Job *j;
 508
 509         assert(m);
 510
 511         /* Checks whether applying this transaction means that
 512          * existing jobs would be replaced */
 513
 514         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 515
 516                 /* Assume merged */
 517                 assert(!j->transaction_prev);
 518                 assert(!j->transaction_next);
 519
 520                 if (j->unit->meta.job &&
 521                     j->unit->meta.job != j &&
 522                     !job_type_is_superset(j->type, j->unit->meta.job->type))
 523                         return -EEXIST;
 524         }
 525
 526         return 0;
 527 }
 528
 529 static void transaction_minimize_impact(Manager *m) {
 530         bool again;
 531         assert(m);
 532
 533         /* Drops all unnecessary jobs that reverse already active jobs
 534          * or that stop a running service. */
 535
 536         do {
 537                 Job *j;
 538                 Iterator i;
 539
 540                 again = false;
 541
 542                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 543                         LIST_FOREACH(transaction, j, j) {
 544
 545                                 /* If it matters, we shouldn't drop it */
 546                                 if (j->matters_to_anchor)
 547                                         continue;
 548
 549                                 /* Would this stop a running service?
 550                                  * Would this change an existing job?
 551                                  * If so, let's drop this entry */
 552                                 if ((j->type != JOB_STOP || UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(j->unit))) &&
 553                                     (!j->unit->meta.job  || job_type_is_conflicting(j->type, j->unit->meta.job->state)))
 554                                         continue;
 555
 556                                 /* Ok, let's get rid of this */
 557                                 log_debug("Deleting %s/%s to minimize impact", unit_id(j->unit), job_type_to_string(j->type));
 558                                 transaction_delete_job(m, j);
 559                                 again = true;
 560                                 break;
 561                         }
 562
 563                         if (again)
 564                                 break;
 565                 }
 566
 567         } while (again);
 568 }
 569
 570 static int transaction_apply(Manager *m, JobMode mode) {
 571         Iterator i;
 572         Job *j;
 573         int r;
 574
 575         /* Moves the transaction jobs to the set of active jobs */
 576
 577         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 578                 /* Assume merged */
 579                 assert(!j->transaction_prev);
 580                 assert(!j->transaction_next);
 581
 582                 if (j->installed)
 583                         continue;
 584
 585                 if ((r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j)) < 0)
 586                         goto rollback;
 587         }
 588
 589         while ((j = hashmap_steal_first(m->transaction_jobs))) {
 590                 if (j->installed)
 591                         continue;
 592
 593                 if (j->unit->meta.job)
 594                         job_free(j->unit->meta.job);
 595
 596                 j->unit->meta.job = j;
 597                 j->installed = true;
 598
 599                 /* We're fully installed. Now let's free data we don't
 600                  * need anymore. */
 601
 602                 assert(!j->transaction_next);
 603                 assert(!j->transaction_prev);
 604
 605                 job_schedule_run(j);
 606         }
 607
 608         /* As last step, kill all remaining job dependencies. */
 609         transaction_clean_dependencies(m);
 610
 611         return 0;
 612
 613 rollback:
 614
 615         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 616                 if (j->installed)
 617                         continue;
 618
 619                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 620         }
 621
 622         return r;
 623 }
 624
 625 static int transaction_activate(Manager *m, JobMode mode) {
 626         int r;
 627         unsigned generation = 1;
 628
 629         assert(m);
 630
 631         /* This applies the changes recorded in transaction_jobs to
 632          * the actual list of jobs, if possible. */
 633
 634         /* First step: figure out which jobs matter */
 635         transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
 636
 637         /* Second step: Try not to stop any running services if
 638          * we don't have to. Don't try to reverse running
 639          * jobs if we don't have to. */
 640         transaction_minimize_impact(m);
 641
 642         for (;;) {
 643                 /* Third step: Let's remove unneeded jobs that might
 644                  * be lurking. */
 645                 transaction_collect_garbage(m);
 646
 647                 /* Fourth step: verify order makes sense and correct
 648                  * cycles if necessary and possible */
 649                 if ((r = transaction_verify_order(m, &generation)) >= 0)
 650                         break;
 651
 652                 if (r != -EAGAIN)
 653                         goto rollback;
 654
 655                 /* Let's see if the resulting transaction ordering
 656                  * graph is still cyclic... */
 657         }
 658
 659         for (;;) {
 660                 /* Fifth step: let's drop unmergeable entries if
 661                  * necessary and possible, merge entries we can
 662                  * merge */
 663                 if ((r = transaction_merge_jobs(m)) >= 0)
 664                         break;
 665
 666                 if (r != -EAGAIN)
 667                         goto rollback;
 668
 669                 /* Sixth step: an entry got dropped, let's garbage
 670                  * collect its dependencies. */
 671                 transaction_collect_garbage(m);
 672
 673                 /* Let's see if the resulting transaction still has
 674                  * unmergeable entries ... */
 675         }
 676
 677         /* Seventh step: check whether we can actually apply this */
 678         if (mode == JOB_FAIL)
 679                 if ((r = transaction_is_destructive(m, mode)) < 0)
 680                         goto rollback;
 681
 682         /* Eights step: apply changes */
 683         if ((r = transaction_apply(m, mode)) < 0)
 684                 goto rollback;
 685
 686         assert(hashmap_isempty(m->transaction_jobs));
 687         assert(!m->transaction_anchor);
 688
 689         return 0;
 690
 691 rollback:
 692         transaction_abort(m);
 693         return r;
 694 }
 695
 696 static Job* transaction_add_one_job(Manager *m, JobType type, Unit *unit, bool force, bool *is_new) {
 697         Job *j, *f;
 698         int r;
 699
 700         assert(m);
 701         assert(unit);
 702
 703         /* Looks for an axisting prospective job and returns that. If
 704          * it doesn't exist it is created and added to the prospective
 705          * jobs list. */
 706
 707         f = hashmap_get(m->transaction_jobs, unit);
 708
 709         LIST_FOREACH(transaction, j, f) {
 710                 assert(j->unit == unit);
 711
 712                 if (j->type == type) {
 713                         if (is_new)
 714                                 *is_new = false;
 715                         return j;
 716                 }
 717         }
 718
 719         if (unit->meta.job && unit->meta.job->type == type)
 720                 j = unit->meta.job;
 721         else if (!(j = job_new(m, type, unit)))
 722                 return NULL;
 723
 724         j->generation = 0;
 725         j->marker = NULL;
 726         j->matters_to_anchor = false;
 727         j->forced = force;
 728
 729         LIST_PREPEND(Job, transaction, f, j);
 730
 731         if ((r = hashmap_replace(m->transaction_jobs, unit, f)) < 0) {
 732                 job_free(j);
 733                 return NULL;
 734         }
 735
 736         if (is_new)
 737                 *is_new = true;
 738
 739         return j;
 740 }
 741
 742 void manager_transaction_unlink_job(Manager *m, Job *j) {
 743         assert(m);
 744         assert(j);
 745
 746         if (j->transaction_prev)
 747                 j->transaction_prev->transaction_next = j->transaction_next;
 748         else if (j->transaction_next)
 749                 hashmap_replace(m->transaction_jobs, j->unit, j->transaction_next);
 750         else
 751                 hashmap_remove_value(m->transaction_jobs, j->unit, j);
 752
 753         if (j->transaction_next)
 754                 j->transaction_next->transaction_prev = j->transaction_prev;
 755
 756         j->transaction_prev = j->transaction_next = NULL;
 757
 758         while (j->subject_list)
 759                 job_dependency_free(j->subject_list);
 760
 761         while (j->object_list) {
 762                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 763
 764                 job_dependency_free(j->object_list);
 765
 766                 if (other) {
 767                         log_debug("Deleting job %s/%s as dependency of job %s/%s",
 768                                   unit_id(other->unit), job_type_to_string(other->type),
 769                                   unit_id(j->unit), job_type_to_string(j->type));
 770                         transaction_delete_job(m, other);
 771                 }
 772         }
 773 }
 774
 775 static int transaction_add_job_and_dependencies(Manager *m, JobType type, Unit *unit, Job *by, bool matters, bool force, Job **_ret) {
 776         Job *ret;
 777         Iterator i;
 778         Unit *dep;
 779         int r;
 780         bool is_new;
 781
 782         assert(m);
 783         assert(type < _JOB_TYPE_MAX);
 784         assert(unit);
 785
 786         if (unit->meta.load_state != UNIT_LOADED)
 787                 return -EINVAL;
 788
 789         if (!unit_job_is_applicable(unit, type))
 790                 return -EBADR;
 791
 792         /* First add the job. */
 793         if (!(ret = transaction_add_one_job(m, type, unit, force, &is_new)))
 794                 return -ENOMEM;
 795
 796         /* Then, add a link to the job. */
 797         if (!job_dependency_new(by, ret, matters))
 798                 return -ENOMEM;
 799
 800         if (is_new) {
 801                 /* Finally, recursively add in all dependencies. */
 802                 if (type == JOB_START || type == JOB_RELOAD_OR_START) {
 803                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRES], i)
 804                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 805                                         goto fail;
 806                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUIRES], i)
 807                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
 808                                         goto fail;
 809                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_WANTS], i)
 810                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, force, NULL)) < 0 && r != -EBADR)
 811                                         goto fail;
 812                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUISITE], i)
 813                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 814                                         goto fail;
 815                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUISITE], i)
 816                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
 817                                         goto fail;
 818                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_CONFLICTS], i)
 819                                 if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 820                                         goto fail;
 821
 822                 } else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
 823
 824                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRED_BY], i)
 825                                 if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 826                                         goto fail;
 827                 }
 828
 829                 /* JOB_VERIFY_STARTED, JOB_RELOAD require no dependency handling */
 830         }
 831
 832         return 0;
 833
 834 fail:
 835         return r;
 836 }
 837
 838 int manager_add_job(Manager *m, JobType type, Unit *unit, JobMode mode, bool force, Job **_ret) {
 839         int r;
 840         Job *ret;
 841
 842         assert(m);
 843         assert(type < _JOB_TYPE_MAX);
 844         assert(unit);
 845         assert(mode < _JOB_MODE_MAX);
 846
 847         if ((r = transaction_add_job_and_dependencies(m, type, unit, NULL, true, force, &ret))) {
 848                 transaction_abort(m);
 849                 return r;
 850         }
 851
 852         if ((r = transaction_activate(m, mode)) < 0)
 853                 return r;
 854
 855         if (_ret)
 856                 *_ret = ret;
 857
 858         return 0;
 859 }
 860
 861 Job *manager_get_job(Manager *m, uint32_t id) {
 862         assert(m);
 863
 864         return hashmap_get(m->jobs, UINT32_TO_PTR(id));
 865 }
 866
 867 Unit *manager_get_unit(Manager *m, const char *name) {
 868         assert(m);
 869         assert(name);
 870
 871         return hashmap_get(m->units, name);
 872 }
 873
 874 static void dispatch_load_queue(Manager *m) {
 875         Meta *meta;
 876
 877         assert(m);
 878
 879         /* Make sure we are not run recursively */
 880         if (m->dispatching_load_queue)
 881                 return;
 882
 883         m->dispatching_load_queue = true;
 884
 885         /* Dispatches the load queue. Takes a unit from the queue and
 886          * tries to load its data until the queue is empty */
 887
 888         while ((meta = m->load_queue)) {
 889                 assert(meta->in_load_queue);
 890
 891                 unit_load(UNIT(meta));
 892         }
 893
 894         m->dispatching_load_queue = false;
 895 }
 896
 897 int manager_load_unit(Manager *m, const char *path, Unit **_ret) {
 898         Unit *ret;
 899         int r;
 900         const char *name;
 901
 902         assert(m);
 903         assert(path);
 904         assert(_ret);
 905
 906         /* This will load the service information files, but not actually
 907          * start any services or anything. */
 908
 909         name = file_name_from_path(path);
 910
 911         if ((ret = manager_get_unit(m, name))) {
 912                 *_ret = ret;
 913                 return 0;
 914         }
 915
 916         if (!(ret = unit_new(m)))
 917                 return -ENOMEM;
 918
 919         if (is_path(path)) {
 920                 if (!(ret->meta.load_path = strdup(path))) {
 921                         unit_free(ret);
 922                         return -ENOMEM;
 923                 }
 924         }
 925
 926         if ((r = unit_add_name(ret, name)) < 0) {
 927                 unit_free(ret);
 928                 return r;
 929         }
 930
 931         unit_add_to_load_queue(ret);
 932         dispatch_load_queue(m);
 933
 934         *_ret = ret;
 935         return 0;
 936 }
 937
 938 void manager_dump_jobs(Manager *s, FILE *f, const char *prefix) {
 939         Iterator i;
 940         Job *j;
 941
 942         assert(s);
 943         assert(f);
 944
 945         HASHMAP_FOREACH(j, s->jobs, i)
 946                 job_dump(j, f, prefix);
 947 }
 948
 949 void manager_dump_units(Manager *s, FILE *f, const char *prefix) {
 950         Iterator i;
 951         Unit *u;
 952         const char *t;
 953
 954         assert(s);
 955         assert(f);
 956
 957         HASHMAP_FOREACH_KEY(u, t, s->units, i)
 958                 if (unit_id(u) == t)
 959                         unit_dump(u, f, prefix);
 960 }
 961
 962 void manager_clear_jobs(Manager *m) {
 963         Job *j;
 964
 965         assert(m);
 966
 967         transaction_abort(m);
 968
 969         while ((j = hashmap_first(m->jobs)))
 970                 job_free(j);
 971 }
 972
 973 void manager_dispatch_run_queue(Manager *m) {
 974         Job *j;
 975
 976         if (m->dispatching_run_queue)
 977                 return;
 978
 979         m->dispatching_run_queue = true;
 980
 981         while ((j = m->run_queue)) {
 982                 assert(j->installed);
 983                 assert(j->in_run_queue);
 984
 985                 job_run_and_invalidate(j);
 986         }
 987
 988         m->dispatching_run_queue = false;
 989 }
 990
 991 static int manager_dispatch_sigchld(Manager *m) {
 992         assert(m);
 993
 994         log_debug("dispatching SIGCHLD");
 995
 996         for (;;) {
 997                 siginfo_t si;
 998                 Unit *u;
 999
1000                 zero(si);
1001                 if (waitid(P_ALL, 0, &si, WEXITED|WNOHANG) < 0) {
1002
1003                         if (errno == ECHILD)
1004                                 break;
1005
1006                         return -errno;
1007                 }
1008
1009                 if (si.si_pid == 0)
1010                         break;
1011
1012                 if (si.si_code != CLD_EXITED && si.si_code != CLD_KILLED && si.si_code != CLD_DUMPED)
1013                         continue;
1014
1015                 log_debug("child %llu died (code=%s, status=%i)", (long long unsigned) si.si_pid, sigchld_code(si.si_code), si.si_status);
1016
1017                 if (!(u = hashmap_remove(m->watch_pids, UINT32_TO_PTR(si.si_pid))))
1018                         continue;
1019
1020                 UNIT_VTABLE(u)->sigchld_event(u, si.si_pid, si.si_code, si.si_status);
1021         }
1022
1023         return 0;
1024 }
1025
1026 static int manager_process_signal_fd(Manager *m, bool *quit) {
1027         ssize_t n;
1028         struct signalfd_siginfo sfsi;
1029         bool sigchld = false;
1030
1031         assert(m);
1032
1033         for (;;) {
1034                 if ((n = read(m->signal_watch.fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
1035
1036                         if (n >= 0)
1037                                 return -EIO;
1038
1039                         if (errno == EAGAIN)
1040                                 break;
1041
1042                         return -errno;
1043                 }
1044
1045                 switch (sfsi.ssi_signo) {
1046
1047                 case SIGCHLD:
1048                         sigchld = true;
1049                         break;
1050
1051                 case SIGINT:
1052                 case SIGTERM:
1053                         *quit = true;
1054                         return 0;
1055
1056                 default:
1057                         log_info("Got unhandled signal <%s>.", strsignal(sfsi.ssi_signo));
1058                 }
1059         }
1060
1061         if (sigchld)
1062                 return manager_dispatch_sigchld(m);
1063
1064         return 0;
1065 }
1066
1067 static int process_event(Manager *m, struct epoll_event *ev, bool *quit) {
1068         int r;
1069         Watch *w;
1070
1071         assert(m);
1072         assert(ev);
1073
1074         assert(w = ev->data.ptr);
1075
1076         switch (w->type) {
1077
1078         case WATCH_SIGNAL_FD:
1079
1080                 /* An incoming signal? */
1081                 if (ev->events != POLLIN)
1082                         return -EINVAL;
1083
1084                 if ((r = manager_process_signal_fd(m, quit)) < 0)
1085                         return r;
1086
1087                 break;
1088
1089         case WATCH_FD:
1090
1091                 /* Some fd event, to be dispatched to the units */
1092                 UNIT_VTABLE(w->unit)->fd_event(w->unit, w->fd, ev->events, w);
1093                 break;
1094
1095         case WATCH_TIMER: {
1096                 uint64_t v;
1097                 ssize_t k;
1098
1099                 /* Some timer event, to be dispatched to the units */
1100                 if ((k = read(ev->data.fd, &v, sizeof(v))) != sizeof(v)) {
1101
1102                         if (k < 0 && (errno == EINTR || errno == EAGAIN))
1103                                 break;
1104
1105                         return k < 0 ? -errno : -EIO;
1106                 }
1107
1108                 UNIT_VTABLE(w->unit)->timer_event(w->unit, v, w);
1109                 break;
1110         }
1111
1112         default:
1113                 assert_not_reached("Unknown epoll event type.");
1114         }
1115
1116         return 0;
1117 }
1118
1119 int manager_loop(Manager *m) {
1120         int r;
1121         bool quit = false;
1122
1123         assert(m);
1124
1125         for (;;) {
1126                 struct epoll_event event;
1127                 int n;
1128
1129                 manager_dispatch_run_queue(m);
1130
1131                 if ((n = epoll_wait(m->epoll_fd, &event, 1, -1)) < 0) {
1132
1133                         if (errno == -EINTR)
1134                                 continue;
1135
1136                         return -errno;
1137                 }
1138
1139                 assert(n == 1);
1140
1141                 if ((r = process_event(m, &event, &quit)) < 0)
1142                         return r;
1143
1144                 if (quit)
1145                         return 0;
1146         }
1147 }