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