src/core/transaction.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <fcntl.h>
   4 #include <unistd.h>
   5
   6 #include "alloc-util.h"
   7 #include "bus-common-errors.h"
   8 #include "bus-error.h"
   9 #include "dbus-unit.h"
  10 #include "strv.h"
  11 #include "terminal-util.h"
  12 #include "transaction.h"
  13
  14 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies);
  15
  16 static void transaction_delete_job(Transaction *tr, Job *j, bool delete_dependencies) {
  17         assert(tr);
  18         assert(j);
  19
  20         /* Deletes one job from the transaction */
  21
  22         transaction_unlink_job(tr, j, delete_dependencies);
  23
  24         job_free(j);
  25 }
  26
  27 static void transaction_delete_unit(Transaction *tr, Unit *u) {
  28         Job *j;
  29
  30         /* Deletes all jobs associated with a certain unit from the
  31          * transaction */
  32
  33         while ((j = hashmap_get(tr->jobs, u)))
  34                 transaction_delete_job(tr, j, true);
  35 }
  36
  37 static void transaction_abort(Transaction *tr) {
  38         Job *j;
  39
  40         assert(tr);
  41
  42         while ((j = hashmap_first(tr->jobs)))
  43                 transaction_delete_job(tr, j, false);
  44
  45         assert(hashmap_isempty(tr->jobs));
  46 }
  47
  48 static void transaction_find_jobs_that_matter_to_anchor(Job *j, unsigned generation) {
  49         assert(j);
  50
  51         /* A recursive sweep through the graph that marks all units
  52          * that matter to the anchor job, i.e. are directly or
  53          * indirectly a dependency of the anchor job via paths that
  54          * are fully marked as mattering. */
  55
  56         j->matters_to_anchor = true;
  57         j->generation = generation;
  58
  59         LIST_FOREACH(subject, l, j->subject_list) {
  60
  61                 /* This link does not matter */
  62                 if (!l->matters)
  63                         continue;
  64
  65                 /* This unit has already been marked */
  66                 if (l->object->generation == generation)
  67                         continue;
  68
  69                 transaction_find_jobs_that_matter_to_anchor(l->object, generation);
  70         }
  71 }
  72
  73 static void transaction_merge_and_delete_job(Transaction *tr, Job *j, Job *other, JobType t) {
  74         JobDependency *last;
  75
  76         assert(j);
  77         assert(other);
  78         assert(j->unit == other->unit);
  79         assert(!j->installed);
  80
  81         /* Merges 'other' into 'j' and then deletes 'other'. */
  82
  83         j->type = t;
  84         j->state = JOB_WAITING;
  85         j->irreversible = j->irreversible || other->irreversible;
  86         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
  87
  88         /* Patch us in as new owner of the JobDependency objects */
  89         last = NULL;
  90         LIST_FOREACH(subject, l, other->subject_list) {
  91                 assert(l->subject == other);
  92                 l->subject = j;
  93                 last = l;
  94         }
  95
  96         /* Merge both lists */
  97         if (last) {
  98                 last->subject_next = j->subject_list;
  99                 if (j->subject_list)
 100                         j->subject_list->subject_prev = last;
 101                 j->subject_list = other->subject_list;
 102         }
 103
 104         /* Patch us in as new owner of the JobDependency objects */
 105         last = NULL;
 106         LIST_FOREACH(object, l, other->object_list) {
 107                 assert(l->object == other);
 108                 l->object = j;
 109                 last = l;
 110         }
 111
 112         /* Merge both lists */
 113         if (last) {
 114                 last->object_next = j->object_list;
 115                 if (j->object_list)
 116                         j->object_list->object_prev = last;
 117                 j->object_list = other->object_list;
 118         }
 119
 120         /* Kill the other job */
 121         other->subject_list = NULL;
 122         other->object_list = NULL;
 123         transaction_delete_job(tr, other, true);
 124 }
 125
 126 _pure_ static bool job_is_conflicted_by(Job *j) {
 127         assert(j);
 128
 129         /* Returns true if this job is pulled in by a least one
 130          * ConflictedBy dependency. */
 131
 132         LIST_FOREACH(object, l, j->object_list)
 133                 if (l->conflicts)
 134                         return true;
 135
 136         return false;
 137 }
 138
 139 static int delete_one_unmergeable_job(Transaction *tr, Job *job) {
 140         assert(job);
 141
 142         /* Tries to delete one item in the linked list
 143          * j->transaction_next->transaction_next->... that conflicts
 144          * with another one, in an attempt to make an inconsistent
 145          * transaction work. */
 146
 147         /* We rely here on the fact that if a merged with b does not
 148          * merge with c, either a or b merge with c neither */
 149         LIST_FOREACH(transaction, j, job)
 150                 LIST_FOREACH(transaction, k, j->transaction_next) {
 151                         Job *d;
 152
 153                         /* Is this one mergeable? Then skip it */
 154                         if (job_type_is_mergeable(j->type, k->type))
 155                                 continue;
 156
 157                         /* Ok, we found two that conflict, let's see if we can
 158                          * drop one of them */
 159                         if (!j->matters_to_anchor && !k->matters_to_anchor) {
 160
 161                                 /* Both jobs don't matter, so let's
 162                                  * find the one that is smarter to
 163                                  * remove. Let's think positive and
 164                                  * rather remove stops then starts --
 165                                  * except if something is being
 166                                  * stopped because it is conflicted by
 167                                  * another unit in which case we
 168                                  * rather remove the start. */
 169
 170                                 log_unit_debug(j->unit,
 171                                                "Looking at job %s/%s conflicted_by=%s",
 172                                                j->unit->id, job_type_to_string(j->type),
 173                                                yes_no(j->type == JOB_STOP && job_is_conflicted_by(j)));
 174                                 log_unit_debug(k->unit,
 175                                                "Looking at job %s/%s conflicted_by=%s",
 176                                                k->unit->id, job_type_to_string(k->type),
 177                                                yes_no(k->type == JOB_STOP && job_is_conflicted_by(k)));
 178
 179                                 if (j->type == JOB_STOP) {
 180
 181                                         if (job_is_conflicted_by(j))
 182                                                 d = k;
 183                                         else
 184                                                 d = j;
 185
 186                                 } else if (k->type == JOB_STOP) {
 187
 188                                         if (job_is_conflicted_by(k))
 189                                                 d = j;
 190                                         else
 191                                                 d = k;
 192                                 } else
 193                                         d = j;
 194
 195                         } else if (!j->matters_to_anchor)
 196                                 d = j;
 197                         else if (!k->matters_to_anchor)
 198                                 d = k;
 199                         else
 200                                 return -ENOEXEC;
 201
 202                         /* Ok, we can drop one, so let's do so. */
 203                         log_unit_debug(d->unit,
 204                                        "Fixing conflicting jobs %s/%s,%s/%s by deleting job %s/%s",
 205                                        j->unit->id, job_type_to_string(j->type),
 206                                        k->unit->id, job_type_to_string(k->type),
 207                                        d->unit->id, job_type_to_string(d->type));
 208                         transaction_delete_job(tr, d, true);
 209                         return 0;
 210                 }
 211
 212         return -EINVAL;
 213 }
 214
 215 static int transaction_merge_jobs(Transaction *tr, sd_bus_error *e) {
 216         Job *j;
 217         int r;
 218
 219         assert(tr);
 220
 221         /* First step, check whether any of the jobs for one specific
 222          * task conflict. If so, try to drop one of them. */
 223         HASHMAP_FOREACH(j, tr->jobs) {
 224                 JobType t;
 225
 226                 t = j->type;
 227                 LIST_FOREACH(transaction, k, j->transaction_next) {
 228                         if (job_type_merge_and_collapse(&t, k->type, j->unit) >= 0)
 229                                 continue;
 230
 231                         /* OK, we could not merge all jobs for this
 232                          * action. Let's see if we can get rid of one
 233                          * of them */
 234
 235                         r = delete_one_unmergeable_job(tr, j);
 236                         if (r >= 0)
 237                                 /* Ok, we managed to drop one, now
 238                                  * let's ask our callers to call us
 239                                  * again after garbage collecting */
 240                                 return -EAGAIN;
 241
 242                         /* We couldn't merge anything. Failure */
 243                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_JOBS_CONFLICTING,
 244                                                  "Transaction contains conflicting jobs '%s' and '%s' for %s. "
 245                                                  "Probably contradicting requirement dependencies configured.",
 246                                                  job_type_to_string(t),
 247                                                  job_type_to_string(k->type),
 248                                                  k->unit->id);
 249                 }
 250         }
 251
 252         /* Second step, merge the jobs. */
 253         HASHMAP_FOREACH(j, tr->jobs) {
 254                 JobType t = j->type;
 255
 256                 /* Merge all transaction jobs for j->unit */
 257                 LIST_FOREACH(transaction, k, j->transaction_next)
 258                         assert_se(job_type_merge_and_collapse(&t, k->type, j->unit) == 0);
 259
 260                 Job *k;
 261                 while ((k = j->transaction_next)) {
 262                         if (tr->anchor_job == k) {
 263                                 transaction_merge_and_delete_job(tr, k, j, t);
 264                                 j = k;
 265                         } else
 266                                 transaction_merge_and_delete_job(tr, j, k, t);
 267                 }
 268
 269                 assert(!j->transaction_next);
 270                 assert(!j->transaction_prev);
 271         }
 272
 273         return 0;
 274 }
 275
 276 static void transaction_drop_redundant(Transaction *tr) {
 277         bool again;
 278
 279         /* Goes through the transaction and removes all jobs of the units whose jobs are all noops. If not
 280          * all of a unit's jobs are redundant, they are kept. */
 281
 282         assert(tr);
 283
 284         do {
 285                 Job *j;
 286
 287                 again = false;
 288
 289                 HASHMAP_FOREACH(j, tr->jobs) {
 290                         bool keep = false;
 291
 292                         LIST_FOREACH(transaction, k, j)
 293                                 if (tr->anchor_job == k ||
 294                                     !job_type_is_redundant(k->type, unit_active_state(k->unit)) ||
 295                                     (k->unit->job && job_type_is_conflicting(k->type, k->unit->job->type))) {
 296                                         keep = true;
 297                                         break;
 298                                 }
 299
 300                         if (!keep) {
 301                                 log_trace("Found redundant job %s/%s, dropping from transaction.",
 302                                           j->unit->id, job_type_to_string(j->type));
 303                                 transaction_delete_job(tr, j, false);
 304                                 again = true;
 305                                 break;
 306                         }
 307                 }
 308         } while (again);
 309 }
 310
 311 _pure_ static bool job_matters_to_anchor(Job *job) {
 312         assert(job);
 313         assert(!job->transaction_prev);
 314
 315         /* Checks whether at least one of the jobs for this transaction matters to the anchor. */
 316
 317         LIST_FOREACH(transaction, j, job)
 318                 if (j->matters_to_anchor)
 319                         return true;
 320
 321         return false;
 322 }
 323
 324 static char* merge_unit_ids(const char* unit_log_field, char * const* pairs) {
 325         _cleanup_free_ char *ans = NULL;
 326         size_t size = 0;
 327
 328         assert(unit_log_field);
 329
 330         STRV_FOREACH_PAIR(unit_id, job_type, pairs) {
 331                 size_t next;
 332
 333                 if (size > 0)
 334                         ans[size - 1] = '\n';
 335
 336                 next = strlen(unit_log_field) + strlen(*unit_id);
 337                 if (!GREEDY_REALLOC(ans, size + next + 1))
 338                         return NULL;
 339
 340                 sprintf(ans + size, "%s%s", unit_log_field, *unit_id);
 341                 size += next + 1;
 342         }
 343
 344         if (!ans)
 345                 return strdup("");
 346
 347         return TAKE_PTR(ans);
 348 }
 349
 350 static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsigned generation, sd_bus_error *e) {
 351
 352         static const UnitDependencyAtom directions[] = {
 353                 UNIT_ATOM_BEFORE,
 354                 UNIT_ATOM_AFTER,
 355         };
 356
 357         int r;
 358
 359         assert(tr);
 360         assert(j);
 361         assert(!j->transaction_prev);
 362
 363         /* Does a recursive sweep through the ordering graph, looking for a cycle. If we find a cycle we try
 364          * to break it. */
 365
 366         /* Have we seen this before? */
 367         if (j->generation == generation) {
 368                 Job *k, *delete = NULL;
 369                 _cleanup_free_ char **array = NULL, *unit_ids = NULL;
 370
 371                 /* If the marker is NULL we have been here already and decided the job was loop-free from
 372                  * here. Hence shortcut things and return right-away. */
 373                 if (!j->marker)
 374                         return 0;
 375
 376                 /* So, the marker is not NULL and we already have been here. We have a cycle. Let's try to
 377                  * break it. We go backwards in our path and try to find a suitable job to remove. We use the
 378                  * marker to find our way back, since smart how we are we stored our way back in there. */
 379                 for (k = from; k; k = ((k->generation == generation && k->marker != k) ? k->marker : NULL)) {
 380
 381                         /* For logging below */
 382                         if (strv_push_pair(&array, k->unit->id, (char*) job_type_to_string(k->type)) < 0)
 383                                 log_oom();
 384
 385                         if (!delete && hashmap_contains(tr->jobs, k->unit) && !job_matters_to_anchor(k))
 386                                 /* Ok, we can drop this one, so let's do so. */
 387                                 delete = k;
 388
 389                         /* Check if this in fact was the beginning of the cycle */
 390                         if (k == j)
 391                                 break;
 392                 }
 393
 394                 unit_ids = merge_unit_ids(j->manager->unit_log_field, array); /* ignore error */
 395
 396                 STRV_FOREACH_PAIR(unit_id, job_type, array)
 397                         /* logging for j not k here to provide a consistent narrative */
 398                         log_struct(LOG_WARNING,
 399                                    LOG_UNIT_MESSAGE(j->unit,
 400                                                     "Found %s on %s/%s",
 401                                                     unit_id == array ? "ordering cycle" : "dependency",
 402                                                     *unit_id, *job_type),
 403                                    "%s", strna(unit_ids));
 404
 405                 if (delete) {
 406                         const char *status;
 407                         /* logging for j not k here to provide a consistent narrative */
 408                         log_struct(LOG_ERR,
 409                                    LOG_UNIT_MESSAGE(j->unit,
 410                                                     "Job %s/%s deleted to break ordering cycle starting with %s/%s",
 411                                                     delete->unit->id, job_type_to_string(delete->type),
 412                                                     j->unit->id, job_type_to_string(j->type)),
 413                                    "%s", strna(unit_ids));
 414
 415                         if (log_get_show_color())
 416                                 status = ANSI_HIGHLIGHT_RED " SKIP " ANSI_NORMAL;
 417                         else
 418                                 status = " SKIP ";
 419
 420                         unit_status_printf(delete->unit,
 421                                            STATUS_TYPE_NOTICE,
 422                                            status,
 423                                            "Ordering cycle found, skipping %s",
 424                                            unit_status_string(delete->unit, NULL));
 425                         transaction_delete_unit(tr, delete->unit);
 426                         return -EAGAIN;
 427                 }
 428
 429                 log_struct(LOG_ERR,
 430                            LOG_UNIT_MESSAGE(j->unit, "Unable to break cycle starting with %s/%s",
 431                                             j->unit->id, job_type_to_string(j->type)),
 432                            "%s", strna(unit_ids));
 433
 434                 return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_ORDER_IS_CYCLIC,
 435                                          "Transaction order is cyclic. See system logs for details.");
 436         }
 437
 438         /* Make the marker point to where we come from, so that we can
 439          * find our way backwards if we want to break a cycle. We use
 440          * a special marker for the beginning: we point to
 441          * ourselves. */
 442         j->marker = from ?: j;
 443         j->generation = generation;
 444
 445         /* Actual ordering of jobs depends on the unit ordering dependency and job types. We need to traverse
 446          * the graph over 'before' edges in the actual job execution order. We traverse over both unit
 447          * ordering dependencies and we test with job_compare() whether it is the 'before' edge in the job
 448          * execution ordering. */
 449         for (size_t d = 0; d < ELEMENTSOF(directions); d++) {
 450                 Unit *u;
 451
 452                 UNIT_FOREACH_DEPENDENCY(u, j->unit, directions[d]) {
 453                         Job *o;
 454
 455                         /* Is there a job for this unit? */
 456                         o = hashmap_get(tr->jobs, u);
 457                         if (!o) {
 458                                 /* Ok, there is no job for this in the transaction, but maybe there is
 459                                  * already one running? */
 460                                 o = u->job;
 461                                 if (!o)
 462                                         continue;
 463                         }
 464
 465                         /* Cut traversing if the job j is not really *before* o. */
 466                         if (job_compare(j, o, directions[d]) >= 0)
 467                                 continue;
 468
 469                         r = transaction_verify_order_one(tr, o, j, generation, e);
 470                         if (r < 0)
 471                                 return r;
 472                 }
 473         }
 474
 475         /* Ok, let's backtrack, and remember that this entry is not on
 476          * our path anymore. */
 477         j->marker = NULL;
 478
 479         return 0;
 480 }
 481
 482 static int transaction_verify_order(Transaction *tr, unsigned *generation, sd_bus_error *e) {
 483         Job *j;
 484         int r;
 485         unsigned g;
 486
 487         assert(tr);
 488         assert(generation);
 489
 490         /* Check if the ordering graph is cyclic. If it is, try to fix
 491          * that up by dropping one of the jobs. */
 492
 493         g = (*generation)++;
 494
 495         HASHMAP_FOREACH(j, tr->jobs) {
 496                 r = transaction_verify_order_one(tr, j, NULL, g, e);
 497                 if (r < 0)
 498                         return r;
 499         }
 500
 501         return 0;
 502 }
 503
 504 static void transaction_collect_garbage(Transaction *tr) {
 505         bool again;
 506
 507         assert(tr);
 508
 509         /* Drop jobs that are not required by any other job */
 510
 511         do {
 512                 Job *j;
 513
 514                 again = false;
 515
 516                 HASHMAP_FOREACH(j, tr->jobs) {
 517                         if (tr->anchor_job == j)
 518                                 continue;
 519
 520                         if (!j->object_list) {
 521                                 log_trace("Garbage collecting job %s/%s", j->unit->id, job_type_to_string(j->type));
 522                                 transaction_delete_job(tr, j, true);
 523                                 again = true;
 524                                 break;
 525                         }
 526
 527                         log_trace("Keeping job %s/%s because of %s/%s",
 528                                   j->unit->id, job_type_to_string(j->type),
 529                                   j->object_list->subject ? j->object_list->subject->unit->id : "root",
 530                                   j->object_list->subject ? job_type_to_string(j->object_list->subject->type) : "root");
 531                 }
 532
 533         } while (again);
 534 }
 535
 536 static int transaction_is_destructive(Transaction *tr, JobMode mode, sd_bus_error *e) {
 537         Job *j;
 538
 539         assert(tr);
 540
 541         /* Checks whether applying this transaction means that
 542          * existing jobs would be replaced */
 543
 544         HASHMAP_FOREACH(j, tr->jobs) {
 545
 546                 /* Assume merged */
 547                 assert(!j->transaction_prev);
 548                 assert(!j->transaction_next);
 549
 550                 if (j->unit->job && (mode == JOB_FAIL || j->unit->job->irreversible) &&
 551                     job_type_is_conflicting(j->unit->job->type, j->type))
 552                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_IS_DESTRUCTIVE,
 553                                                  "Transaction for %s/%s is destructive (%s has '%s' job queued, but '%s' is included in transaction).",
 554                                                  tr->anchor_job->unit->id, job_type_to_string(tr->anchor_job->type),
 555                                                  j->unit->id, job_type_to_string(j->unit->job->type), job_type_to_string(j->type));
 556         }
 557
 558         return 0;
 559 }
 560
 561 static void transaction_minimize_impact(Transaction *tr) {
 562         Job *head;
 563
 564         assert(tr);
 565
 566         /* Drops all unnecessary jobs that reverse already active jobs
 567          * or that stop a running service. */
 568
 569 rescan:
 570         HASHMAP_FOREACH(head, tr->jobs) {
 571                 LIST_FOREACH(transaction, j, head) {
 572                         bool stops_running_service, changes_existing_job;
 573
 574                         /* If it matters, we shouldn't drop it */
 575                         if (j->matters_to_anchor)
 576                                 continue;
 577
 578                         /* Would this stop a running service?
 579                          * Would this change an existing job?
 580                          * If so, let's drop this entry */
 581
 582                         stops_running_service =
 583                                 j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 584
 585                         changes_existing_job =
 586                                 j->unit->job &&
 587                                 job_type_is_conflicting(j->type, j->unit->job->type);
 588
 589                         if (!stops_running_service && !changes_existing_job)
 590                                 continue;
 591
 592                         if (stops_running_service)
 593                                 log_unit_debug(j->unit,
 594                                                "%s/%s would stop a running service.",
 595                                                j->unit->id, job_type_to_string(j->type));
 596
 597                         if (changes_existing_job)
 598                                 log_unit_debug(j->unit,
 599                                                "%s/%s would change existing job.",
 600                                                j->unit->id, job_type_to_string(j->type));
 601
 602                         /* Ok, let's get rid of this */
 603                         log_unit_debug(j->unit,
 604                                        "Deleting %s/%s to minimize impact.",
 605                                        j->unit->id, job_type_to_string(j->type));
 606
 607                         transaction_delete_job(tr, j, true);
 608                         goto rescan;
 609                 }
 610         }
 611 }
 612
 613 static int transaction_apply(
 614                 Transaction *tr,
 615                 Manager *m,
 616                 JobMode mode,
 617                 Set *affected_jobs) {
 618
 619         Job *j;
 620         int r;
 621
 622         /* Moves the transaction jobs to the set of active jobs */
 623
 624         if (IN_SET(mode, JOB_ISOLATE, JOB_FLUSH)) {
 625
 626                 /* When isolating first kill all installed jobs which
 627                  * aren't part of the new transaction */
 628                 HASHMAP_FOREACH(j, m->jobs) {
 629                         assert(j->installed);
 630
 631                         if (j->unit->ignore_on_isolate)
 632                                 continue;
 633
 634                         if (hashmap_contains(tr->jobs, j->unit))
 635                                 continue;
 636
 637                         /* Not invalidating recursively. Avoids triggering
 638                          * OnFailure= actions of dependent jobs. Also avoids
 639                          * invalidating our iterator. */
 640                         job_finish_and_invalidate(j, JOB_CANCELED, false, false);
 641                 }
 642         }
 643
 644         HASHMAP_FOREACH(j, tr->jobs) {
 645                 /* Assume merged */
 646                 assert(!j->transaction_prev);
 647                 assert(!j->transaction_next);
 648
 649                 r = hashmap_ensure_put(&m->jobs, NULL, UINT32_TO_PTR(j->id), j);
 650                 if (r < 0)
 651                         goto rollback;
 652         }
 653
 654         while ((j = hashmap_steal_first(tr->jobs))) {
 655                 Job *installed_job;
 656
 657                 /* Clean the job dependencies */
 658                 transaction_unlink_job(tr, j, false);
 659
 660                 installed_job = job_install(j);
 661                 if (installed_job != j) {
 662                         /* j has been merged into a previously installed job */
 663                         if (tr->anchor_job == j)
 664                                 tr->anchor_job = installed_job;
 665                         hashmap_remove_value(m->jobs, UINT32_TO_PTR(j->id), j);
 666                         job_free(j);
 667                         j = installed_job;
 668                 }
 669
 670                 job_add_to_run_queue(j);
 671                 job_add_to_dbus_queue(j);
 672                 job_start_timer(j, false);
 673                 job_shutdown_magic(j);
 674
 675                 /* When 'affected' is specified, let's track all in it all jobs that were touched because of
 676                  * this transaction. */
 677                 if (affected_jobs)
 678                         (void) set_put(affected_jobs, j);
 679         }
 680
 681         return 0;
 682
 683 rollback:
 684
 685         HASHMAP_FOREACH(j, tr->jobs)
 686                 hashmap_remove_value(m->jobs, UINT32_TO_PTR(j->id), j);
 687
 688         return r;
 689 }
 690
 691 int transaction_activate(
 692                 Transaction *tr,
 693                 Manager *m,
 694                 JobMode mode,
 695                 Set *affected_jobs,
 696                 sd_bus_error *e) {
 697
 698         Job *j;
 699         int r;
 700         unsigned generation = 1;
 701
 702         assert(tr);
 703
 704         /* This applies the changes recorded in tr->jobs to
 705          * the actual list of jobs, if possible. */
 706
 707         /* Reset the generation counter of all installed jobs. The detection of cycles
 708          * looks at installed jobs. If they had a non-zero generation from some previous
 709          * walk of the graph, the algorithm would break. */
 710         HASHMAP_FOREACH(j, m->jobs)
 711                 j->generation = 0;
 712
 713         /* First step: figure out which jobs matter */
 714         transaction_find_jobs_that_matter_to_anchor(tr->anchor_job, generation++);
 715
 716         /* Second step: Try not to stop any running services if
 717          * we don't have to. Don't try to reverse running
 718          * jobs if we don't have to. */
 719         if (mode == JOB_FAIL)
 720                 transaction_minimize_impact(tr);
 721
 722         /* Third step: Drop redundant jobs */
 723         transaction_drop_redundant(tr);
 724
 725         for (;;) {
 726                 /* Fourth step: Let's remove unneeded jobs that might
 727                  * be lurking. */
 728                 if (mode != JOB_ISOLATE)
 729                         transaction_collect_garbage(tr);
 730
 731                 /* Fifth step: verify order makes sense and correct
 732                  * cycles if necessary and possible */
 733                 r = transaction_verify_order(tr, &generation, e);
 734                 if (r >= 0)
 735                         break;
 736
 737                 if (r != -EAGAIN)
 738                         return log_warning_errno(r, "Requested transaction contains an unfixable cyclic ordering dependency: %s", bus_error_message(e, r));
 739
 740                 /* Let's see if the resulting transaction ordering
 741                  * graph is still cyclic... */
 742         }
 743
 744         for (;;) {
 745                 /* Sixth step: let's drop unmergeable entries if
 746                  * necessary and possible, merge entries we can
 747                  * merge */
 748                 r = transaction_merge_jobs(tr, e);
 749                 if (r >= 0)
 750                         break;
 751
 752                 if (r != -EAGAIN)
 753                         return log_warning_errno(r, "Requested transaction contains unmergeable jobs: %s", bus_error_message(e, r));
 754
 755                 /* Seventh step: an entry got dropped, let's garbage
 756                  * collect its dependencies. */
 757                 if (mode != JOB_ISOLATE)
 758                         transaction_collect_garbage(tr);
 759
 760                 /* Let's see if the resulting transaction still has
 761                  * unmergeable entries ... */
 762         }
 763
 764         /* Eights step: Drop redundant jobs again, if the merging now allows us to drop more. */
 765         transaction_drop_redundant(tr);
 766
 767         /* Ninth step: check whether we can actually apply this */
 768         r = transaction_is_destructive(tr, mode, e);
 769         if (r < 0)
 770                 return log_notice_errno(r, "Requested transaction contradicts existing jobs: %s", bus_error_message(e, r));
 771
 772         /* Tenth step: apply changes */
 773         r = transaction_apply(tr, m, mode, affected_jobs);
 774         if (r < 0)
 775                 return log_warning_errno(r, "Failed to apply transaction: %m");
 776
 777         assert(hashmap_isempty(tr->jobs));
 778
 779         if (!hashmap_isempty(m->jobs)) {
 780                 /* Are there any jobs now? Then make sure we have the
 781                  * idle pipe around. We don't really care too much
 782                  * whether this works or not, as the idle pipe is a
 783                  * feature for cosmetics, not actually useful for
 784                  * anything beyond that. */
 785
 786                 if (m->idle_pipe[0] < 0 && m->idle_pipe[1] < 0 &&
 787                     m->idle_pipe[2] < 0 && m->idle_pipe[3] < 0) {
 788                         (void) pipe2(m->idle_pipe, O_NONBLOCK|O_CLOEXEC);
 789                         (void) pipe2(m->idle_pipe + 2, O_NONBLOCK|O_CLOEXEC);
 790                 }
 791         }
 792
 793         return 0;
 794 }
 795
 796 static Job* transaction_add_one_job(Transaction *tr, JobType type, Unit *unit, bool *is_new) {
 797         Job *j, *f;
 798
 799         assert(tr);
 800         assert(unit);
 801
 802         /* Looks for an existing prospective job and returns that. If
 803          * it doesn't exist it is created and added to the prospective
 804          * jobs list. */
 805
 806         f = hashmap_get(tr->jobs, unit);
 807
 808         LIST_FOREACH(transaction, i, f) {
 809                 assert(i->unit == unit);
 810
 811                 if (i->type == type) {
 812                         if (is_new)
 813                                 *is_new = false;
 814                         return i;
 815                 }
 816         }
 817
 818         j = job_new(unit, type);
 819         if (!j)
 820                 return NULL;
 821
 822         j->generation = 0;
 823         j->marker = NULL;
 824         j->matters_to_anchor = false;
 825         j->irreversible = tr->irreversible;
 826
 827         LIST_PREPEND(transaction, f, j);
 828
 829         if (hashmap_replace(tr->jobs, unit, f) < 0) {
 830                 LIST_REMOVE(transaction, f, j);
 831                 job_free(j);
 832                 return NULL;
 833         }
 834
 835         if (is_new)
 836                 *is_new = true;
 837
 838         log_trace("Added job %s/%s to transaction.", unit->id, job_type_to_string(type));
 839
 840         return j;
 841 }
 842
 843 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies) {
 844         assert(tr);
 845         assert(j);
 846
 847         if (j->transaction_prev)
 848                 j->transaction_prev->transaction_next = j->transaction_next;
 849         else if (j->transaction_next)
 850                 hashmap_replace(tr->jobs, j->unit, j->transaction_next);
 851         else
 852                 hashmap_remove_value(tr->jobs, j->unit, j);
 853
 854         if (j->transaction_next)
 855                 j->transaction_next->transaction_prev = j->transaction_prev;
 856
 857         j->transaction_prev = j->transaction_next = NULL;
 858
 859         while (j->subject_list)
 860                 job_dependency_free(j->subject_list);
 861
 862         while (j->object_list) {
 863                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 864
 865                 job_dependency_free(j->object_list);
 866
 867                 if (other && delete_dependencies) {
 868                         log_unit_debug(other->unit,
 869                                        "Deleting job %s/%s as dependency of job %s/%s",
 870                                        other->unit->id, job_type_to_string(other->type),
 871                                        j->unit->id, job_type_to_string(j->type));
 872                         transaction_delete_job(tr, other, delete_dependencies);
 873                 }
 874         }
 875 }
 876
 877 void transaction_add_propagate_reload_jobs(
 878                 Transaction *tr,
 879                 Unit *unit,
 880                 Job *by,
 881                 TransactionAddFlags flags) {
 882
 883         JobType nt;
 884         Unit *dep;
 885         int r;
 886
 887         assert(tr);
 888         assert(unit);
 889
 890         UNIT_FOREACH_DEPENDENCY(dep, unit, UNIT_ATOM_PROPAGATES_RELOAD_TO) {
 891                 _cleanup_(sd_bus_error_free) sd_bus_error e = SD_BUS_ERROR_NULL;
 892
 893                 nt = job_type_collapse(JOB_TRY_RELOAD, dep);
 894                 if (nt == JOB_NOP)
 895                         continue;
 896
 897                 r = transaction_add_job_and_dependencies(tr, nt, dep, by, flags, &e);
 898                 if (r < 0)
 899                         log_unit_warning(dep,
 900                                          "Cannot add dependency reload job, ignoring: %s",
 901                                          bus_error_message(&e, r));
 902         }
 903 }
 904
 905 int transaction_add_job_and_dependencies(
 906                 Transaction *tr,
 907                 JobType type,
 908                 Unit *unit,
 909                 Job *by,
 910                 TransactionAddFlags flags,
 911                 sd_bus_error *e) {
 912
 913         bool is_new;
 914         Job *ret;
 915         int r;
 916
 917         assert(tr);
 918         assert(type < _JOB_TYPE_MAX);
 919         assert(type < _JOB_TYPE_MAX_IN_TRANSACTION);
 920         assert(unit);
 921
 922         /* Before adding jobs for this unit, let's ensure that its state has been loaded This matters when
 923          * jobs are spawned as part of coldplugging itself (see e. g. path_coldplug()).  This way, we
 924          * "recursively" coldplug units, ensuring that we do not look at state of not-yet-coldplugged
 925          * units. */
 926         if (MANAGER_IS_RELOADING(unit->manager))
 927                 unit_coldplug(unit);
 928
 929         if (by)
 930                 log_trace("Pulling in %s/%s from %s/%s", unit->id, job_type_to_string(type), by->unit->id, job_type_to_string(by->type));
 931
 932         /* Safety check that the unit is a valid state, i.e. not in UNIT_STUB or UNIT_MERGED which should only be set
 933          * temporarily. */
 934         if (!UNIT_IS_LOAD_COMPLETE(unit->load_state))
 935                 return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED, "Unit %s is not loaded properly.", unit->id);
 936
 937         if (type != JOB_STOP) {
 938                 r = bus_unit_validate_load_state(unit, e);
 939                 /* The time-based cache allows to start new units without daemon-reload, but if they are
 940                  * already referenced (because of dependencies or ordering) then we have to force a load of
 941                  * the fragment. As an optimization, check first if anything in the usual paths was modified
 942                  * since the last time the cache was loaded. Also check if the last time an attempt to load
 943                  * the unit was made was before the most recent cache refresh, so that we know we need to try
 944                  * again — even if the cache is current, it might have been updated in a different context
 945                  * before we had a chance to retry loading this particular unit.
 946                  *
 947                  * Given building up the transaction is a synchronous operation, attempt
 948                  * to load the unit immediately. */
 949                 if (r < 0 && manager_unit_cache_should_retry_load(unit)) {
 950                         sd_bus_error_free(e);
 951                         unit->load_state = UNIT_STUB;
 952                         r = unit_load(unit);
 953                         if (r < 0 || unit->load_state == UNIT_STUB)
 954                                 unit->load_state = UNIT_NOT_FOUND;
 955                         r = bus_unit_validate_load_state(unit, e);
 956                 }
 957                 if (r < 0)
 958                         return r;
 959         }
 960
 961         if (!unit_job_is_applicable(unit, type))
 962                 return sd_bus_error_setf(e, BUS_ERROR_JOB_TYPE_NOT_APPLICABLE,
 963                                          "Job type %s is not applicable for unit %s.",
 964                                          job_type_to_string(type), unit->id);
 965
 966         /* First add the job. */
 967         ret = transaction_add_one_job(tr, type, unit, &is_new);
 968         if (!ret)
 969                 return -ENOMEM;
 970
 971         if (FLAGS_SET(flags, TRANSACTION_IGNORE_ORDER))
 972                 ret->ignore_order = true;
 973
 974         /* Then, add a link to the job. */
 975         if (by) {
 976                 if (!job_dependency_new(by, ret, FLAGS_SET(flags, TRANSACTION_MATTERS), FLAGS_SET(flags, TRANSACTION_CONFLICTS)))
 977                         return -ENOMEM;
 978         } else {
 979                 /* If the job has no parent job, it is the anchor job. */
 980                 assert(!tr->anchor_job);
 981                 tr->anchor_job = ret;
 982         }
 983
 984         if (!is_new || FLAGS_SET(flags, TRANSACTION_IGNORE_REQUIREMENTS) || type == JOB_NOP)
 985                 return 0;
 986
 987         _cleanup_set_free_ Set *following = NULL;
 988         Unit *dep;
 989
 990         /* If we are following some other unit, make sure we add all dependencies of everybody following. */
 991         if (unit_following_set(ret->unit, &following) > 0)
 992                 SET_FOREACH(dep, following) {
 993                         r = transaction_add_job_and_dependencies(tr, type, dep, ret, flags & TRANSACTION_IGNORE_ORDER, e);
 994                         if (r < 0) {
 995                                 log_unit_full_errno(dep, r == -ERFKILL ? LOG_INFO : LOG_WARNING, r,
 996                                                     "Cannot add dependency job, ignoring: %s",
 997                                                     bus_error_message(e, r));
 998                                 sd_bus_error_free(e);
 999                         }
1000                 }
1001
1002         /* Finally, recursively add in all dependencies. */
1003         if (IN_SET(type, JOB_START, JOB_RESTART)) {
1004                 UNIT_FOREACH_DEPENDENCY(dep, ret->unit, UNIT_ATOM_PULL_IN_START) {
1005                         r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, TRANSACTION_MATTERS | (flags & TRANSACTION_IGNORE_ORDER), e);
1006                         if (r < 0) {
1007                                 if (r != -EBADR) /* job type not applicable */
1008                                         goto fail;
1009
1010                                 sd_bus_error_free(e);
1011                         }
1012                 }
1013
1014                 UNIT_FOREACH_DEPENDENCY(dep, ret->unit, UNIT_ATOM_PULL_IN_START_IGNORED) {
1015                         r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, flags & TRANSACTION_IGNORE_ORDER, e);
1016                         if (r < 0) {
1017                                 /* unit masked, job type not applicable and unit not found are not considered
1018                                  * as errors. */
1019                                 log_unit_full_errno(dep,
1020                                                     IN_SET(r, -ERFKILL, -EBADR, -ENOENT) ? LOG_DEBUG : LOG_WARNING,
1021                                                     r, "Cannot add dependency job, ignoring: %s",
1022                                                     bus_error_message(e, r));
1023                                 sd_bus_error_free(e);
1024                         }
1025                 }
1026
1027                 UNIT_FOREACH_DEPENDENCY(dep, ret->unit, UNIT_ATOM_PULL_IN_VERIFY) {
1028                         r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, TRANSACTION_MATTERS | (flags & TRANSACTION_IGNORE_ORDER), e);
1029                         if (r < 0) {
1030                                 if (r != -EBADR) /* job type not applicable */
1031                                         goto fail;
1032
1033                                 sd_bus_error_free(e);
1034                         }
1035                 }
1036
1037                 UNIT_FOREACH_DEPENDENCY(dep, ret->unit, UNIT_ATOM_PULL_IN_STOP) {
1038                         r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, TRANSACTION_MATTERS | TRANSACTION_CONFLICTS | (flags & TRANSACTION_IGNORE_ORDER), e);
1039                         if (r < 0) {
1040                                 if (r != -EBADR) /* job type not applicable */
1041                                         goto fail;
1042
1043                                 sd_bus_error_free(e);
1044                         }
1045                 }
1046
1047                 UNIT_FOREACH_DEPENDENCY(dep, ret->unit, UNIT_ATOM_PULL_IN_STOP_IGNORED) {
1048                         r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, flags & TRANSACTION_IGNORE_ORDER, e);
1049                         if (r < 0) {
1050                                 log_unit_warning(dep,
1051                                                  "Cannot add dependency job, ignoring: %s",
1052                                                  bus_error_message(e, r));
1053                                 sd_bus_error_free(e);
1054                         }
1055                 }
1056         }
1057
1058         _cleanup_set_free_ Set *propagated_restart = NULL;
1059
1060         if (type == JOB_RESTART || (type == JOB_START && FLAGS_SET(flags, TRANSACTION_PROPAGATE_START_AS_RESTART))) {
1061
1062                 /* We propagate RESTART only as TRY_RESTART, in order not to start dependencies that
1063                  * are not around. */
1064
1065                 UNIT_FOREACH_DEPENDENCY(dep, ret->unit, UNIT_ATOM_PROPAGATE_RESTART) {
1066                         JobType nt;
1067
1068                         r = set_ensure_put(&propagated_restart, NULL, dep);
1069                         if (r < 0)
1070                                 return r;
1071
1072                         nt = job_type_collapse(JOB_TRY_RESTART, dep);
1073                         if (nt == JOB_NOP)
1074                                 continue;
1075
1076                         r = transaction_add_job_and_dependencies(tr, nt, dep, ret, TRANSACTION_MATTERS | (flags & TRANSACTION_IGNORE_ORDER), e);
1077                         if (r < 0) {
1078                                 if (r != -EBADR) /* job type not applicable */
1079                                         return r;
1080
1081                                 sd_bus_error_free(e);
1082                         }
1083                 }
1084         }
1085
1086         if (type == JOB_STOP) {
1087                 /* The 'stop' part of a restart job is also propagated to units with UNIT_ATOM_PROPAGATE_STOP. */
1088
1089                 UNIT_FOREACH_DEPENDENCY(dep, ret->unit, UNIT_ATOM_PROPAGATE_STOP) {
1090                         /* Units experienced restart propagation are skipped */
1091                         if (set_contains(propagated_restart, dep))
1092                                 continue;
1093
1094                         r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, TRANSACTION_MATTERS | (flags & TRANSACTION_IGNORE_ORDER), e);
1095                         if (r < 0) {
1096                                 if (r != -EBADR) /* job type not applicable */
1097                                         return r;
1098
1099                                 sd_bus_error_free(e);
1100                         }
1101                 }
1102         }
1103
1104         if (type == JOB_RELOAD)
1105                 transaction_add_propagate_reload_jobs(tr, ret->unit, ret, flags & TRANSACTION_IGNORE_ORDER);
1106
1107         /* JOB_VERIFY_ACTIVE requires no dependency handling */
1108
1109         return 0;
1110
1111 fail:
1112         /* Recursive call failed to add required jobs so let's drop top level job as well. */
1113         log_unit_debug_errno(unit, r, "Cannot add dependency job to transaction, deleting job %s/%s again: %s",
1114                              unit->id, job_type_to_string(type), bus_error_message(e, r));
1115
1116         transaction_delete_job(tr, ret, /* delete_dependencies= */ false);
1117         return r;
1118 }
1119
1120 static bool shall_stop_on_isolate(Transaction *tr, Unit *u) {
1121         assert(tr);
1122         assert(u);
1123
1124         if (u->ignore_on_isolate)
1125                 return false;
1126
1127         /* Is there already something listed for this? */
1128         if (hashmap_contains(tr->jobs, u))
1129                 return false;
1130
1131         return true;
1132 }
1133
1134 int transaction_add_isolate_jobs(Transaction *tr, Manager *m) {
1135         Unit *u;
1136         char *k;
1137         int r;
1138
1139         assert(tr);
1140         assert(m);
1141
1142         HASHMAP_FOREACH_KEY(u, k, m->units) {
1143                 _cleanup_(sd_bus_error_free) sd_bus_error e = SD_BUS_ERROR_NULL;
1144                 Unit *o;
1145
1146                 /* Ignore aliases */
1147                 if (u->id != k)
1148                         continue;
1149
1150                 /* No need to stop inactive units */
1151                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(u)) && !u->job)
1152                         continue;
1153
1154                 if (!shall_stop_on_isolate(tr, u))
1155                         continue;
1156
1157                 /* Keep units that are triggered by units we want to keep around. */
1158                 bool keep = false;
1159                 UNIT_FOREACH_DEPENDENCY(o, u, UNIT_ATOM_TRIGGERED_BY)
1160                         if (!shall_stop_on_isolate(tr, o)) {
1161                                 keep = true;
1162                                 break;
1163                         }
1164                 if (keep)
1165                         continue;
1166
1167                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, u, tr->anchor_job, TRANSACTION_MATTERS, &e);
1168                 if (r < 0)
1169                         log_unit_warning_errno(u, r, "Cannot add isolate job, ignoring: %s", bus_error_message(&e, r));
1170         }
1171
1172         return 0;
1173 }
1174
1175 int transaction_add_triggering_jobs(Transaction *tr, Unit *u) {
1176         Unit *trigger;
1177         int r;
1178
1179         assert(tr);
1180         assert(u);
1181
1182         UNIT_FOREACH_DEPENDENCY(trigger, u, UNIT_ATOM_TRIGGERED_BY) {
1183                 _cleanup_(sd_bus_error_free) sd_bus_error e = SD_BUS_ERROR_NULL;
1184
1185                 /* No need to stop inactive jobs */
1186                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(trigger)) && !trigger->job)
1187                         continue;
1188
1189                 /* Is there already something listed for this? */
1190                 if (hashmap_contains(tr->jobs, trigger))
1191                         continue;
1192
1193                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, trigger, tr->anchor_job, TRANSACTION_MATTERS, &e);
1194                 if (r < 0)
1195                         log_unit_warning_errno(u, r, "Cannot add triggered by job, ignoring: %s", bus_error_message(&e, r));
1196         }
1197
1198         return 0;
1199 }
1200
1201 Transaction *transaction_new(bool irreversible) {
1202         Transaction *tr;
1203
1204         tr = new0(Transaction, 1);
1205         if (!tr)
1206                 return NULL;
1207
1208         tr->jobs = hashmap_new(NULL);
1209         if (!tr->jobs)
1210                 return mfree(tr);
1211
1212         tr->irreversible = irreversible;
1213
1214         return tr;
1215 }
1216
1217 Transaction *transaction_free(Transaction *tr) {
1218         if (!tr)
1219                 return NULL;
1220
1221         assert(hashmap_isempty(tr->jobs));
1222         hashmap_free(tr->jobs);
1223
1224         return mfree(tr);
1225 }
1226
1227 Transaction *transaction_abort_and_free(Transaction *tr) {
1228         if (!tr)
1229                 return NULL;
1230
1231         transaction_abort(tr);
1232
1233         return transaction_free(tr);
1234 }