src/core/transaction.c

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