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 int manager_setup_signals(Manager *m) {
  21         sigset_t mask;
  22         struct epoll_event ev;
  23
  24         assert(m);
  25
  26         assert_se(reset_all_signal_handlers() == 0);
  27
  28         assert_se(sigemptyset(&mask) == 0);
  29         assert_se(sigaddset(&mask, SIGCHLD) == 0);
  30         assert_se(sigaddset(&mask, SIGINT) == 0);   /* Kernel sends us this on control-alt-del */
  31         assert_se(sigaddset(&mask, SIGWINCH) == 0); /* Kernel sends us this on kbrequest (alt-arrowup) */
  32         assert_se(sigaddset(&mask, SIGTERM) == 0);
  33         assert_se(sigaddset(&mask, SIGHUP) == 0);
  34         assert_se(sigaddset(&mask, SIGUSR1) == 0);
  35         assert_se(sigaddset(&mask, SIGUSR2) == 0);
  36         assert_se(sigaddset(&mask, SIGPIPE) == 0);
  37         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
  38
  39         m->signal_watch.type = WATCH_SIGNAL;
  40         if ((m->signal_watch.fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0)
  41                 return -errno;
  42
  43         zero(ev);
  44         ev.events = EPOLLIN;
  45         ev.data.ptr = &m->signal_watch;
  46
  47         if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->signal_watch.fd, &ev) < 0)
  48                 return -errno;
  49
  50         return 0;
  51 }
  52
  53 Manager* manager_new(void) {
  54         Manager *m;
  55
  56         if (!(m = new0(Manager, 1)))
  57                 return NULL;
  58
  59         m->signal_watch.fd = m->mount_watch.fd = m->udev_watch.fd = m->epoll_fd = -1;
  60
  61         if (!(m->units = hashmap_new(string_hash_func, string_compare_func)))
  62                 goto fail;
  63
  64         if (!(m->jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
  65                 goto fail;
  66
  67         if (!(m->transaction_jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
  68                 goto fail;
  69
  70         if (!(m->watch_pids = hashmap_new(trivial_hash_func, trivial_compare_func)))
  71                 goto fail;
  72
  73         if ((m->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0)
  74                 goto fail;
  75
  76         if (manager_setup_signals(m) < 0)
  77                 goto fail;
  78
  79         return m;
  80
  81 fail:
  82         manager_free(m);
  83         return NULL;
  84 }
  85
  86 void manager_free(Manager *m) {
  87         UnitType c;
  88         Unit *u;
  89         Job *j;
  90
  91         assert(m);
  92
  93         while ((j = hashmap_first(m->transaction_jobs)))
  94                 job_free(j);
  95
  96         while ((u = hashmap_first(m->units)))
  97                 unit_free(u);
  98
  99         for (c = 0; c < _UNIT_TYPE_MAX; c++)
 100                 if (unit_vtable[c]->shutdown)
 101                         unit_vtable[c]->shutdown(m);
 102
 103         hashmap_free(m->units);
 104         hashmap_free(m->jobs);
 105         hashmap_free(m->transaction_jobs);
 106         hashmap_free(m->watch_pids);
 107
 108         if (m->epoll_fd >= 0)
 109                 close_nointr(m->epoll_fd);
 110         if (m->signal_watch.fd >= 0)
 111                 close_nointr(m->signal_watch.fd);
 112
 113         free(m);
 114 }
 115
 116 int manager_coldplug(Manager *m) {
 117         int r;
 118         UnitType c;
 119         Iterator i;
 120         Unit *u;
 121         char *k;
 122
 123         assert(m);
 124
 125         /* First, let's ask every type to load all units from
 126          * disk/kernel that it might know */
 127         for (c = 0; c < _UNIT_TYPE_MAX; c++)
 128                 if (unit_vtable[c]->enumerate)
 129                         if ((r = unit_vtable[c]->enumerate(m)) < 0)
 130                                 return r;
 131
 132         manager_dispatch_load_queue(m);
 133
 134         /* Then, let's set up their initial state. */
 135         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
 136
 137                 /* ignore aliases */
 138                 if (unit_id(u) != k)
 139                         continue;
 140
 141                 if (UNIT_VTABLE(u)->coldplug)
 142                         if ((r = UNIT_VTABLE(u)->coldplug(u)) < 0)
 143                                 return r;
 144         }
 145
 146         return 0;
 147 }
 148
 149 static void transaction_delete_job(Manager *m, Job *j) {
 150         assert(m);
 151         assert(j);
 152
 153         /* Deletes one job from the transaction */
 154
 155         manager_transaction_unlink_job(m, j);
 156
 157         if (!j->installed)
 158                 job_free(j);
 159 }
 160
 161 static void transaction_delete_unit(Manager *m, Unit *u) {
 162         Job *j;
 163
 164         /* Deletes all jobs associated with a certain unit from the
 165          * transaction */
 166
 167         while ((j = hashmap_get(m->transaction_jobs, u)))
 168                 transaction_delete_job(m, j);
 169 }
 170
 171 static void transaction_clean_dependencies(Manager *m) {
 172         Iterator i;
 173         Job *j;
 174
 175         assert(m);
 176
 177         /* Drops all dependencies of all installed jobs */
 178
 179         HASHMAP_FOREACH(j, m->jobs, i) {
 180                 while (j->subject_list)
 181                         job_dependency_free(j->subject_list);
 182                 while (j->object_list)
 183                         job_dependency_free(j->object_list);
 184         }
 185
 186         assert(!m->transaction_anchor);
 187 }
 188
 189 static void transaction_abort(Manager *m) {
 190         Job *j;
 191
 192         assert(m);
 193
 194         while ((j = hashmap_first(m->transaction_jobs)))
 195                 if (j->installed)
 196                         transaction_delete_job(m, j);
 197                 else
 198                         job_free(j);
 199
 200         assert(hashmap_isempty(m->transaction_jobs));
 201
 202         transaction_clean_dependencies(m);
 203 }
 204
 205 static void transaction_find_jobs_that_matter_to_anchor(Manager *m, Job *j, unsigned generation) {
 206         JobDependency *l;
 207
 208         assert(m);
 209
 210         /* A recursive sweep through the graph that marks all units
 211          * that matter to the anchor job, i.e. are directly or
 212          * indirectly a dependency of the anchor job via paths that
 213          * are fully marked as mattering. */
 214
 215         if (j)
 216                 l = j->subject_list;
 217         else
 218                 l = m->transaction_anchor;
 219
 220         LIST_FOREACH(subject, l, l) {
 221
 222                 /* This link does not matter */
 223                 if (!l->matters)
 224                         continue;
 225
 226                 /* This unit has already been marked */
 227                 if (l->object->generation == generation)
 228                         continue;
 229
 230                 l->object->matters_to_anchor = true;
 231                 l->object->generation = generation;
 232
 233                 transaction_find_jobs_that_matter_to_anchor(m, l->object, generation);
 234         }
 235 }
 236
 237 static void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, JobType t) {
 238         JobDependency *l, *last;
 239
 240         assert(j);
 241         assert(other);
 242         assert(j->unit == other->unit);
 243         assert(!j->installed);
 244
 245         /* Merges 'other' into 'j' and then deletes j. */
 246
 247         j->type = t;
 248         j->state = JOB_WAITING;
 249         j->forced = j->forced || other->forced;
 250
 251         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
 252
 253         /* Patch us in as new owner of the JobDependency objects */
 254         last = NULL;
 255         LIST_FOREACH(subject, l, other->subject_list) {
 256                 assert(l->subject == other);
 257                 l->subject = j;
 258                 last = l;
 259         }
 260
 261         /* Merge both lists */
 262         if (last) {
 263                 last->subject_next = j->subject_list;
 264                 if (j->subject_list)
 265                         j->subject_list->subject_prev = last;
 266                 j->subject_list = other->subject_list;
 267         }
 268
 269         /* Patch us in as new owner of the JobDependency objects */
 270         last = NULL;
 271         LIST_FOREACH(object, l, other->object_list) {
 272                 assert(l->object == other);
 273                 l->object = j;
 274                 last = l;
 275         }
 276
 277         /* Merge both lists */
 278         if (last) {
 279                 last->object_next = j->object_list;
 280                 if (j->object_list)
 281                         j->object_list->object_prev = last;
 282                 j->object_list = other->object_list;
 283         }
 284
 285         /* Kill the other job */
 286         other->subject_list = NULL;
 287         other->object_list = NULL;
 288         transaction_delete_job(m, other);
 289 }
 290
 291 static int delete_one_unmergeable_job(Manager *m, Job *j) {
 292         Job *k;
 293
 294         assert(j);
 295
 296         /* Tries to delete one item in the linked list
 297          * j->transaction_next->transaction_next->... that conflicts
 298          * whith another one, in an attempt to make an inconsistent
 299          * transaction work. */
 300
 301         /* We rely here on the fact that if a merged with b does not
 302          * merge with c, either a or b merge with c neither */
 303         LIST_FOREACH(transaction, j, j)
 304                 LIST_FOREACH(transaction, k, j->transaction_next) {
 305                         Job *d;
 306
 307                         /* Is this one mergeable? Then skip it */
 308                         if (job_type_is_mergeable(j->type, k->type))
 309                                 continue;
 310
 311                         /* Ok, we found two that conflict, let's see if we can
 312                          * drop one of them */
 313                         if (!j->matters_to_anchor)
 314                                 d = j;
 315                         else if (!k->matters_to_anchor)
 316                                 d = k;
 317                         else
 318                                 return -ENOEXEC;
 319
 320                         /* Ok, we can drop one, so let's do so. */
 321                         log_debug("Try to fix job merging by deleting job %s/%s", unit_id(d->unit), job_type_to_string(d->type));
 322                         transaction_delete_job(m, d);
 323                         return 0;
 324                 }
 325
 326         return -EINVAL;
 327 }
 328
 329 static int transaction_merge_jobs(Manager *m) {
 330         Job *j;
 331         Iterator i;
 332         int r;
 333
 334         assert(m);
 335
 336         /* First step, check whether any of the jobs for one specific
 337          * task conflict. If so, try to drop one of them. */
 338         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 339                 JobType t;
 340                 Job *k;
 341
 342                 t = j->type;
 343                 LIST_FOREACH(transaction, k, j->transaction_next) {
 344                         if ((r = job_type_merge(&t, k->type)) >= 0)
 345                                 continue;
 346
 347                         /* OK, we could not merge all jobs for this
 348                          * action. Let's see if we can get rid of one
 349                          * of them */
 350
 351                         if ((r = delete_one_unmergeable_job(m, j)) >= 0)
 352                                 /* Ok, we managed to drop one, now
 353                                  * let's ask our callers to call us
 354                                  * again after garbage collecting */
 355                                 return -EAGAIN;
 356
 357                         /* We couldn't merge anything. Failure */
 358                         return r;
 359                 }
 360         }
 361
 362         /* Second step, merge the jobs. */
 363         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 364                 JobType t = j->type;
 365                 Job *k;
 366
 367                 /* Merge all transactions */
 368                 LIST_FOREACH(transaction, k, j->transaction_next)
 369                         assert_se(job_type_merge(&t, k->type) == 0);
 370
 371                 /* If an active job is mergeable, merge it too */
 372                 if (j->unit->meta.job)
 373                         job_type_merge(&t, j->unit->meta.job->type); /* Might fail. Which is OK */
 374
 375                 while ((k = j->transaction_next)) {
 376                         if (j->installed) {
 377                                 transaction_merge_and_delete_job(m, k, j, t);
 378                                 j = k;
 379                         } else
 380                                 transaction_merge_and_delete_job(m, j, k, t);
 381                 }
 382
 383                 assert(!j->transaction_next);
 384                 assert(!j->transaction_prev);
 385         }
 386
 387         return 0;
 388 }
 389
 390 static bool unit_matters_to_anchor(Unit *u, Job *j) {
 391         assert(u);
 392         assert(!j->transaction_prev);
 393
 394         /* Checks whether at least one of the jobs for this unit
 395          * matters to the anchor. */
 396
 397         LIST_FOREACH(transaction, j, j)
 398                 if (j->matters_to_anchor)
 399                         return true;
 400
 401         return false;
 402 }
 403
 404 static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
 405         Iterator i;
 406         Unit *u;
 407         int r;
 408
 409         assert(m);
 410         assert(j);
 411         assert(!j->transaction_prev);
 412
 413         /* Does a recursive sweep through the ordering graph, looking
 414          * for a cycle. If we find cycle we try to break it. */
 415
 416         /* Did we find a cycle? */
 417         if (j->marker && j->generation == generation) {
 418                 Job *k;
 419
 420                 /* So, we already have been here. We have a
 421                  * cycle. Let's try to break it. We go backwards in
 422                  * our path and try to find a suitable job to
 423                  * remove. We use the marker to find our way back,
 424                  * since smart how we are we stored our way back in
 425                  * there. */
 426
 427                 log_debug("Found cycle on %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 428
 429                 for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
 430
 431                         log_debug("Walked on cycle path to %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 432
 433                         if (!k->installed &&
 434                             !unit_matters_to_anchor(k->unit, k)) {
 435                                 /* Ok, we can drop this one, so let's
 436                                  * do so. */
 437                                 log_debug("Breaking order cycle by deleting job %s/%s", unit_id(k->unit), job_type_to_string(k->type));
 438                                 transaction_delete_unit(m, k->unit);
 439                                 return -EAGAIN;
 440                         }
 441
 442                         /* Check if this in fact was the beginning of
 443                          * the cycle */
 444                         if (k == j)
 445                                 break;
 446                 }
 447
 448                 log_debug("Unable to break cycle");
 449
 450                 return -ENOEXEC;
 451         }
 452
 453         /* Make the marker point to where we come from, so that we can
 454          * find our way backwards if we want to break a cycle */
 455         j->marker = from;
 456         j->generation = generation;
 457
 458         /* We assume that the the dependencies are bidirectional, and
 459          * hence can ignore UNIT_AFTER */
 460         SET_FOREACH(u, j->unit->meta.dependencies[UNIT_BEFORE], i) {
 461                 Job *o;
 462
 463                 /* Is there a job for this unit? */
 464                 if (!(o = hashmap_get(m->transaction_jobs, u)))
 465
 466                         /* Ok, there is no job for this in the
 467                          * transaction, but maybe there is already one
 468                          * running? */
 469                         if (!(o = u->meta.job))
 470                                 continue;
 471
 472                 if ((r = transaction_verify_order_one(m, o, j, generation)) < 0)
 473                         return r;
 474         }
 475
 476         /* Ok, let's backtrack, and remember that this entry is not on
 477          * our path anymore. */
 478         j->marker = NULL;
 479
 480         return 0;
 481 }
 482
 483 static int transaction_verify_order(Manager *m, unsigned *generation) {
 484         Job *j;
 485         int r;
 486         Iterator i;
 487
 488         assert(m);
 489         assert(generation);
 490
 491         /* Check if the ordering graph is cyclic. If it is, try to fix
 492          * that up by dropping one of the jobs. */
 493
 494         HASHMAP_FOREACH(j, m->transaction_jobs, i)
 495                 if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
 496                         return r;
 497
 498         return 0;
 499 }
 500
 501 static void transaction_collect_garbage(Manager *m) {
 502         bool again;
 503
 504         assert(m);
 505
 506         /* Drop jobs that are not required by any other job */
 507
 508         do {
 509                 Iterator i;
 510                 Job *j;
 511
 512                 again = false;
 513
 514                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 515                         if (j->object_list)
 516                                 continue;
 517
 518                         log_debug("Garbage collecting job %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 519                         transaction_delete_job(m, j);
 520                         again = true;
 521                         break;
 522                 }
 523
 524         } while (again);
 525 }
 526
 527 static int transaction_is_destructive(Manager *m, JobMode mode) {
 528         Iterator i;
 529         Job *j;
 530
 531         assert(m);
 532
 533         /* Checks whether applying this transaction means that
 534          * existing jobs would be replaced */
 535
 536         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 537
 538                 /* Assume merged */
 539                 assert(!j->transaction_prev);
 540                 assert(!j->transaction_next);
 541
 542                 if (j->unit->meta.job &&
 543                     j->unit->meta.job != j &&
 544                     !job_type_is_superset(j->type, j->unit->meta.job->type))
 545                         return -EEXIST;
 546         }
 547
 548         return 0;
 549 }
 550
 551 static void transaction_minimize_impact(Manager *m) {
 552         bool again;
 553         assert(m);
 554
 555         /* Drops all unnecessary jobs that reverse already active jobs
 556          * or that stop a running service. */
 557
 558         do {
 559                 Job *j;
 560                 Iterator i;
 561
 562                 again = false;
 563
 564                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 565                         LIST_FOREACH(transaction, j, j) {
 566                                 bool stops_running_service, changes_existing_job;
 567
 568                                 /* If it matters, we shouldn't drop it */
 569                                 if (j->matters_to_anchor)
 570                                         continue;
 571
 572                                 /* Would this stop a running service?
 573                                  * Would this change an existing job?
 574                                  * If so, let's drop this entry */
 575
 576                                 stops_running_service =
 577                                         j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 578
 579                                 changes_existing_job =
 580                                         j->unit->meta.job && job_type_is_conflicting(j->type, j->unit->meta.job->state);
 581
 582                                 if (!stops_running_service && !changes_existing_job)
 583                                         continue;
 584
 585                                 if (stops_running_service)
 586                                         log_debug("%s/%s would stop a running service.", unit_id(j->unit), job_type_to_string(j->type));
 587
 588                                 if (changes_existing_job)
 589                                         log_debug("%s/%s would change existing job.", unit_id(j->unit), job_type_to_string(j->type));
 590
 591                                 /* Ok, let's get rid of this */
 592                                 log_debug("Deleting %s/%s to minimize impact.", unit_id(j->unit), job_type_to_string(j->type));
 593
 594                                 transaction_delete_job(m, j);
 595                                 again = true;
 596                                 break;
 597                         }
 598
 599                         if (again)
 600                                 break;
 601                 }
 602
 603         } while (again);
 604 }
 605
 606 static int transaction_apply(Manager *m, JobMode mode) {
 607         Iterator i;
 608         Job *j;
 609         int r;
 610
 611         /* Moves the transaction jobs to the set of active jobs */
 612
 613         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 614                 /* Assume merged */
 615                 assert(!j->transaction_prev);
 616                 assert(!j->transaction_next);
 617
 618                 if (j->installed)
 619                         continue;
 620
 621                 if ((r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j)) < 0)
 622                         goto rollback;
 623         }
 624
 625         while ((j = hashmap_steal_first(m->transaction_jobs))) {
 626                 if (j->installed)
 627                         continue;
 628
 629                 if (j->unit->meta.job)
 630                         job_free(j->unit->meta.job);
 631
 632                 j->unit->meta.job = j;
 633                 j->installed = true;
 634
 635                 /* We're fully installed. Now let's free data we don't
 636                  * need anymore. */
 637
 638                 assert(!j->transaction_next);
 639                 assert(!j->transaction_prev);
 640
 641                 job_schedule_run(j);
 642         }
 643
 644         /* As last step, kill all remaining job dependencies. */
 645         transaction_clean_dependencies(m);
 646
 647         return 0;
 648
 649 rollback:
 650
 651         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 652                 if (j->installed)
 653                         continue;
 654
 655                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 656         }
 657
 658         return r;
 659 }
 660
 661 static int transaction_activate(Manager *m, JobMode mode) {
 662         int r;
 663         unsigned generation = 1;
 664
 665         assert(m);
 666
 667         /* This applies the changes recorded in transaction_jobs to
 668          * the actual list of jobs, if possible. */
 669
 670         /* First step: figure out which jobs matter */
 671         transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
 672
 673         /* Second step: Try not to stop any running services if
 674          * we don't have to. Don't try to reverse running
 675          * jobs if we don't have to. */
 676         transaction_minimize_impact(m);
 677
 678         for (;;) {
 679                 /* Third step: Let's remove unneeded jobs that might
 680                  * be lurking. */
 681                 transaction_collect_garbage(m);
 682
 683                 /* Fourth step: verify order makes sense and correct
 684                  * cycles if necessary and possible */
 685                 if ((r = transaction_verify_order(m, &generation)) >= 0)
 686                         break;
 687
 688                 if (r != -EAGAIN) {
 689                         log_debug("Requested transaction contains an unfixable cyclic ordering dependency: %s", strerror(-r));
 690                         goto rollback;
 691                 }
 692
 693                 /* Let's see if the resulting transaction ordering
 694                  * graph is still cyclic... */
 695         }
 696
 697         for (;;) {
 698                 /* Fifth step: let's drop unmergeable entries if
 699                  * necessary and possible, merge entries we can
 700                  * merge */
 701                 if ((r = transaction_merge_jobs(m)) >= 0)
 702                         break;
 703
 704                 if (r != -EAGAIN) {
 705                         log_debug("Requested transaction contains unmergable jobs: %s", strerror(-r));
 706                         goto rollback;
 707                 }
 708
 709                 /* Sixth step: an entry got dropped, let's garbage
 710                  * collect its dependencies. */
 711                 transaction_collect_garbage(m);
 712
 713                 /* Let's see if the resulting transaction still has
 714                  * unmergeable entries ... */
 715         }
 716
 717         /* Seventh step: check whether we can actually apply this */
 718         if (mode == JOB_FAIL)
 719                 if ((r = transaction_is_destructive(m, mode)) < 0) {
 720                         log_debug("Requested transaction contradicts existing jobs: %s", strerror(-r));
 721                         goto rollback;
 722                 }
 723
 724         /* Eights step: apply changes */
 725         if ((r = transaction_apply(m, mode)) < 0) {
 726                 log_debug("Failed to apply transaction: %s", strerror(-r));
 727                 goto rollback;
 728         }
 729
 730         assert(hashmap_isempty(m->transaction_jobs));
 731         assert(!m->transaction_anchor);
 732
 733         return 0;
 734
 735 rollback:
 736         transaction_abort(m);
 737         return r;
 738 }
 739
 740 static Job* transaction_add_one_job(Manager *m, JobType type, Unit *unit, bool force, bool *is_new) {
 741         Job *j, *f;
 742         int r;
 743
 744         assert(m);
 745         assert(unit);
 746
 747         /* Looks for an axisting prospective job and returns that. If
 748          * it doesn't exist it is created and added to the prospective
 749          * jobs list. */
 750
 751         f = hashmap_get(m->transaction_jobs, unit);
 752
 753         LIST_FOREACH(transaction, j, f) {
 754                 assert(j->unit == unit);
 755
 756                 if (j->type == type) {
 757                         if (is_new)
 758                                 *is_new = false;
 759                         return j;
 760                 }
 761         }
 762
 763         if (unit->meta.job && unit->meta.job->type == type)
 764                 j = unit->meta.job;
 765         else if (!(j = job_new(m, type, unit)))
 766                 return NULL;
 767
 768         j->generation = 0;
 769         j->marker = NULL;
 770         j->matters_to_anchor = false;
 771         j->forced = force;
 772
 773         LIST_PREPEND(Job, transaction, f, j);
 774
 775         if ((r = hashmap_replace(m->transaction_jobs, unit, f)) < 0) {
 776                 job_free(j);
 777                 return NULL;
 778         }
 779
 780         if (is_new)
 781                 *is_new = true;
 782
 783         return j;
 784 }
 785
 786 void manager_transaction_unlink_job(Manager *m, Job *j) {
 787         assert(m);
 788         assert(j);
 789
 790         if (j->transaction_prev)
 791                 j->transaction_prev->transaction_next = j->transaction_next;
 792         else if (j->transaction_next)
 793                 hashmap_replace(m->transaction_jobs, j->unit, j->transaction_next);
 794         else
 795                 hashmap_remove_value(m->transaction_jobs, j->unit, j);
 796
 797         if (j->transaction_next)
 798                 j->transaction_next->transaction_prev = j->transaction_prev;
 799
 800         j->transaction_prev = j->transaction_next = NULL;
 801
 802         while (j->subject_list)
 803                 job_dependency_free(j->subject_list);
 804
 805         while (j->object_list) {
 806                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 807
 808                 job_dependency_free(j->object_list);
 809
 810                 if (other) {
 811                         log_debug("Deleting job %s/%s as dependency of job %s/%s",
 812                                   unit_id(other->unit), job_type_to_string(other->type),
 813                                   unit_id(j->unit), job_type_to_string(j->type));
 814                         transaction_delete_job(m, other);
 815                 }
 816         }
 817 }
 818
 819 static int transaction_add_job_and_dependencies(Manager *m, JobType type, Unit *unit, Job *by, bool matters, bool force, Job **_ret) {
 820         Job *ret;
 821         Iterator i;
 822         Unit *dep;
 823         int r;
 824         bool is_new;
 825
 826         assert(m);
 827         assert(type < _JOB_TYPE_MAX);
 828         assert(unit);
 829
 830         if (unit->meta.load_state != UNIT_LOADED)
 831                 return -EINVAL;
 832
 833         if (!unit_job_is_applicable(unit, type))
 834                 return -EBADR;
 835
 836         /* First add the job. */
 837         if (!(ret = transaction_add_one_job(m, type, unit, force, &is_new)))
 838                 return -ENOMEM;
 839
 840         /* Then, add a link to the job. */
 841         if (!job_dependency_new(by, ret, matters))
 842                 return -ENOMEM;
 843
 844         if (is_new) {
 845                 /* Finally, recursively add in all dependencies. */
 846                 if (type == JOB_START || type == JOB_RELOAD_OR_START) {
 847                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRES], i)
 848                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 849                                         goto fail;
 850                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUIRES], i)
 851                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
 852                                         goto fail;
 853                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_WANTS], i)
 854                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, force, NULL)) < 0 && r != -EBADR)
 855                                         goto fail;
 856                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUISITE], i)
 857                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 858                                         goto fail;
 859                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUISITE], i)
 860                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
 861                                         goto fail;
 862                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_CONFLICTS], i)
 863                                 if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 864                                         goto fail;
 865
 866                 } else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
 867
 868                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRED_BY], i)
 869                                 if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 870                                         goto fail;
 871                 }
 872
 873                 /* JOB_VERIFY_STARTED, JOB_RELOAD require no dependency handling */
 874         }
 875
 876         return 0;
 877
 878 fail:
 879         return r;
 880 }
 881
 882 int manager_add_job(Manager *m, JobType type, Unit *unit, JobMode mode, bool force, Job **_ret) {
 883         int r;
 884         Job *ret;
 885
 886         assert(m);
 887         assert(type < _JOB_TYPE_MAX);
 888         assert(unit);
 889         assert(mode < _JOB_MODE_MAX);
 890
 891         log_debug("Trying to enqueue job %s/%s", unit_id(unit), job_type_to_string(type));
 892
 893         if ((r = transaction_add_job_and_dependencies(m, type, unit, NULL, true, force, &ret))) {
 894                 transaction_abort(m);
 895                 return r;
 896         }
 897
 898         if ((r = transaction_activate(m, mode)) < 0)
 899                 return r;
 900
 901         log_debug("Enqueued job %s/%s", unit_id(unit), job_type_to_string(type));
 902
 903         if (_ret)
 904                 *_ret = ret;
 905
 906         return 0;
 907 }
 908
 909 Job *manager_get_job(Manager *m, uint32_t id) {
 910         assert(m);
 911
 912         return hashmap_get(m->jobs, UINT32_TO_PTR(id));
 913 }
 914
 915 Unit *manager_get_unit(Manager *m, const char *name) {
 916         assert(m);
 917         assert(name);
 918
 919         return hashmap_get(m->units, name);
 920 }
 921
 922 void manager_dispatch_load_queue(Manager *m) {
 923         Meta *meta;
 924
 925         assert(m);
 926
 927         /* Make sure we are not run recursively */
 928         if (m->dispatching_load_queue)
 929                 return;
 930
 931         m->dispatching_load_queue = true;
 932
 933         /* Dispatches the load queue. Takes a unit from the queue and
 934          * tries to load its data until the queue is empty */
 935
 936         while ((meta = m->load_queue)) {
 937                 assert(meta->in_load_queue);
 938
 939                 unit_load(UNIT(meta));
 940         }
 941
 942         m->dispatching_load_queue = false;
 943 }
 944
 945 int manager_load_unit(Manager *m, const char *path, Unit **_ret) {
 946         Unit *ret;
 947         int r;
 948         const char *name;
 949
 950         assert(m);
 951         assert(path);
 952         assert(_ret);
 953
 954         /* This will load the service information files, but not actually
 955          * start any services or anything. */
 956
 957         name = file_name_from_path(path);
 958
 959         if ((ret = manager_get_unit(m, name))) {
 960                 *_ret = ret;
 961                 return 0;
 962         }
 963
 964         if (!(ret = unit_new(m)))
 965                 return -ENOMEM;
 966
 967         if (is_path(path)) {
 968                 if (!(ret->meta.load_path = strdup(path))) {
 969                         unit_free(ret);
 970                         return -ENOMEM;
 971                 }
 972         }
 973
 974         if ((r = unit_add_name(ret, name)) < 0) {
 975                 unit_free(ret);
 976                 return r;
 977         }
 978
 979         unit_add_to_load_queue(ret);
 980         manager_dispatch_load_queue(m);
 981
 982         *_ret = ret;
 983         return 0;
 984 }
 985
 986 void manager_dump_jobs(Manager *s, FILE *f, const char *prefix) {
 987         Iterator i;
 988         Job *j;
 989
 990         assert(s);
 991         assert(f);
 992
 993         HASHMAP_FOREACH(j, s->jobs, i)
 994                 job_dump(j, f, prefix);
 995 }
 996
 997 void manager_dump_units(Manager *s, FILE *f, const char *prefix) {
 998         Iterator i;
 999         Unit *u;
1000         const char *t;
1001
1002         assert(s);
1003         assert(f);
1004
1005         HASHMAP_FOREACH_KEY(u, t, s->units, i)
1006                 if (unit_id(u) == t)
1007                         unit_dump(u, f, prefix);
1008 }
1009
1010 void manager_clear_jobs(Manager *m) {
1011         Job *j;
1012
1013         assert(m);
1014
1015         transaction_abort(m);
1016
1017         while ((j = hashmap_first(m->jobs)))
1018                 job_free(j);
1019 }
1020
1021 void manager_dispatch_run_queue(Manager *m) {
1022         Job *j;
1023
1024         if (m->dispatching_run_queue)
1025                 return;
1026
1027         m->dispatching_run_queue = true;
1028
1029         while ((j = m->run_queue)) {
1030                 assert(j->installed);
1031                 assert(j->in_run_queue);
1032
1033                 job_run_and_invalidate(j);
1034         }
1035
1036         m->dispatching_run_queue = false;
1037 }
1038
1039 static int manager_dispatch_sigchld(Manager *m) {
1040         assert(m);
1041
1042         log_debug("dispatching SIGCHLD");
1043
1044         for (;;) {
1045                 siginfo_t si;
1046                 Unit *u;
1047
1048                 zero(si);
1049                 if (waitid(P_ALL, 0, &si, WEXITED|WNOHANG) < 0) {
1050
1051                         if (errno == ECHILD)
1052                                 break;
1053
1054                         return -errno;
1055                 }
1056
1057                 if (si.si_pid == 0)
1058                         break;
1059
1060                 if (si.si_code != CLD_EXITED && si.si_code != CLD_KILLED && si.si_code != CLD_DUMPED)
1061                         continue;
1062
1063                 log_debug("child %llu died (code=%s, status=%i)", (long long unsigned) si.si_pid, sigchld_code(si.si_code), si.si_status);
1064
1065                 if (!(u = hashmap_remove(m->watch_pids, UINT32_TO_PTR(si.si_pid))))
1066                         continue;
1067
1068                 UNIT_VTABLE(u)->sigchld_event(u, si.si_pid, si.si_code, si.si_status);
1069         }
1070
1071         return 0;
1072 }
1073
1074 static int manager_process_signal_fd(Manager *m, bool *quit) {
1075         ssize_t n;
1076         struct signalfd_siginfo sfsi;
1077         bool sigchld = false;
1078
1079         assert(m);
1080
1081         for (;;) {
1082                 if ((n = read(m->signal_watch.fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
1083
1084                         if (n >= 0)
1085                                 return -EIO;
1086
1087                         if (errno == EAGAIN)
1088                                 break;
1089
1090                         return -errno;
1091                 }
1092
1093                 switch (sfsi.ssi_signo) {
1094
1095                 case SIGCHLD:
1096                         sigchld = true;
1097                         break;
1098
1099                 case SIGINT:
1100                 case SIGTERM:
1101                         *quit = true;
1102                         return 0;
1103
1104                 default:
1105                         log_info("Got unhandled signal <%s>.", strsignal(sfsi.ssi_signo));
1106                 }
1107         }
1108
1109         if (sigchld)
1110                 return manager_dispatch_sigchld(m);
1111
1112         return 0;
1113 }
1114
1115 static int process_event(Manager *m, struct epoll_event *ev, bool *quit) {
1116         int r;
1117         Watch *w;
1118
1119         assert(m);
1120         assert(ev);
1121
1122         assert(w = ev->data.ptr);
1123
1124         switch (w->type) {
1125
1126         case WATCH_SIGNAL:
1127
1128                 /* An incoming signal? */
1129                 if (ev->events != EPOLLIN)
1130                         return -EINVAL;
1131
1132                 if ((r = manager_process_signal_fd(m, quit)) < 0)
1133                         return r;
1134
1135                 break;
1136
1137         case WATCH_FD:
1138
1139                 /* Some fd event, to be dispatched to the units */
1140                 UNIT_VTABLE(w->unit)->fd_event(w->unit, w->fd, ev->events, w);
1141                 break;
1142
1143         case WATCH_TIMER: {
1144                 uint64_t v;
1145                 ssize_t k;
1146
1147                 /* Some timer event, to be dispatched to the units */
1148                 if ((k = read(ev->data.fd, &v, sizeof(v))) != sizeof(v)) {
1149
1150                         if (k < 0 && (errno == EINTR || errno == EAGAIN))
1151                                 break;
1152
1153                         return k < 0 ? -errno : -EIO;
1154                 }
1155
1156                 UNIT_VTABLE(w->unit)->timer_event(w->unit, v, w);
1157                 break;
1158         }
1159
1160         case WATCH_MOUNT:
1161                 /* Some mount table change, intended for the mount subsystem */
1162                 mount_fd_event(m, ev->events);
1163                 break;
1164
1165         case WATCH_UDEV:
1166                 /* Some notification from udev, intended for the device subsystem */
1167                 device_fd_event(m, ev->events);
1168                 break;
1169
1170         default:
1171                 assert_not_reached("Unknown epoll event type.");
1172         }
1173
1174         return 0;
1175 }
1176
1177 int manager_loop(Manager *m) {
1178         int r;
1179         bool quit = false;
1180
1181         assert(m);
1182
1183         for (;;) {
1184                 struct epoll_event event;
1185                 int n;
1186
1187                 manager_dispatch_run_queue(m);
1188
1189                 if ((n = epoll_wait(m->epoll_fd, &event, 1, -1)) < 0) {
1190
1191                         if (errno == -EINTR)
1192                                 continue;
1193
1194                         return -errno;
1195                 }
1196
1197                 assert(n == 1);
1198
1199                 if ((r = process_event(m, &event, &quit)) < 0)
1200                         return r;
1201
1202                 if (quit)
1203                         return 0;
1204         }
1205 }