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         Job *j;
 283         Iterator i;
 284
 285         /* Goes through the transaction and removes all jobs of the units
 286          * whose jobs are all noops. If not all of a unit's jobs are
 287          * redundant, they are kept. */
 288
 289         assert(tr);
 290
 291 rescan:
 292         HASHMAP_FOREACH(j, tr->jobs, i) {
 293                 Job *k;
 294
 295                 LIST_FOREACH(transaction, k, j) {
 296
 297                         if (tr->anchor_job == k ||
 298                             !job_type_is_redundant(k->type, unit_active_state(k->unit)) ||
 299                             (k->unit->job && job_type_is_conflicting(k->type, k->unit->job->type)))
 300                                 goto next_unit;
 301                 }
 302
 303                 log_trace("Found redundant job %s/%s, dropping from transaction.", j->unit->id, job_type_to_string(j->type));
 304                 transaction_delete_job(tr, j, false);
 305                 goto rescan;
 306         next_unit:;
 307         }
 308 }
 309
 310 _pure_ static bool unit_matters_to_anchor(Unit *u, Job *j) {
 311         assert(u);
 312         assert(!j->transaction_prev);
 313
 314         /* Checks whether at least one of the jobs for this unit
 315          * matters to the anchor. */
 316
 317         LIST_FOREACH(transaction, j, j)
 318                 if (j->matters_to_anchor)
 319                         return true;
 320
 321         return false;
 322 }
 323
 324 static char* merge_unit_ids(const char* unit_log_field, char **pairs) {
 325         char **unit_id, **job_type, *ans = NULL;
 326         size_t alloc = 0, size = 0, next;
 327
 328         STRV_FOREACH_PAIR(unit_id, job_type, pairs) {
 329                 next = strlen(unit_log_field) + strlen(*unit_id);
 330                 if (!GREEDY_REALLOC(ans, alloc, size + next + 1)) {
 331                         return mfree(ans);
 332                 }
 333
 334                 sprintf(ans + size, "%s%s", unit_log_field, *unit_id);
 335                 if (*(unit_id+1))
 336                         ans[size + next] =  '\n';
 337                 size += next + 1;
 338         }
 339
 340         return ans;
 341 }
 342
 343 static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsigned generation, sd_bus_error *e) {
 344         Iterator i;
 345         Unit *u;
 346         void *v;
 347         int r;
 348
 349         assert(tr);
 350         assert(j);
 351         assert(!j->transaction_prev);
 352
 353         /* Does a recursive sweep through the ordering graph, looking
 354          * for a cycle. If we find a cycle we try to break it. */
 355
 356         /* Have we seen this before? */
 357         if (j->generation == generation) {
 358                 Job *k, *delete = NULL;
 359                 _cleanup_free_ char **array = NULL, *unit_ids = NULL;
 360                 char **unit_id, **job_type;
 361
 362                 /* If the marker is NULL we have been here already and
 363                  * decided the job was loop-free from here. Hence
 364                  * shortcut things and return right-away. */
 365                 if (!j->marker)
 366                         return 0;
 367
 368                 /* So, the marker is not NULL and we already have been here. We have
 369                  * a cycle. Let's try to break it. We go backwards in our path and
 370                  * try to find a suitable job to remove. We use the marker to find
 371                  * our way back, since smart how we are we stored our way back in
 372                  * there. */
 373
 374                 for (k = from; k; k = ((k->generation == generation && k->marker != k) ? k->marker : NULL)) {
 375
 376                         /* For logging below */
 377                         if (strv_push_pair(&array, k->unit->id, (char*) job_type_to_string(k->type)) < 0)
 378                                 log_oom();
 379
 380                         if (!delete && hashmap_get(tr->jobs, k->unit) && !unit_matters_to_anchor(k->unit, k))
 381                                 /* Ok, we can drop this one, so let's do so. */
 382                                 delete = k;
 383
 384                         /* Check if this in fact was the beginning of the cycle */
 385                         if (k == j)
 386                                 break;
 387                 }
 388
 389                 unit_ids = merge_unit_ids(j->manager->unit_log_field, array); /* ignore error */
 390
 391                 STRV_FOREACH_PAIR(unit_id, job_type, array)
 392                         /* logging for j not k here to provide a consistent narrative */
 393                         log_struct(LOG_WARNING,
 394                                    "MESSAGE=%s: Found %s on %s/%s",
 395                                    j->unit->id,
 396                                    unit_id == array ? "ordering cycle" : "dependency",
 397                                    *unit_id, *job_type,
 398                                    unit_ids);
 399
 400                 if (delete) {
 401                         const char *status;
 402                         /* logging for j not k here to provide a consistent narrative */
 403                         log_struct(LOG_ERR,
 404                                    "MESSAGE=%s: Job %s/%s deleted to break ordering cycle starting with %s/%s",
 405                                    j->unit->id, delete->unit->id, job_type_to_string(delete->type),
 406                                    j->unit->id, job_type_to_string(j->type),
 407                                    unit_ids);
 408
 409                         if (log_get_show_color())
 410                                 status = ANSI_HIGHLIGHT_RED " SKIP " ANSI_NORMAL;
 411                         else
 412                                 status = " SKIP ";
 413
 414                         unit_status_printf(delete->unit, status,
 415                                            "Ordering cycle found, skipping %s");
 416                         transaction_delete_unit(tr, delete->unit);
 417                         return -EAGAIN;
 418                 }
 419
 420                 log_struct(LOG_ERR,
 421                            "MESSAGE=%s: Unable to break cycle starting with %s/%s",
 422                            j->unit->id, j->unit->id, job_type_to_string(j->type),
 423                            unit_ids);
 424
 425                 return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_ORDER_IS_CYCLIC,
 426                                          "Transaction order is cyclic. See system logs for details.");
 427         }
 428
 429         /* Make the marker point to where we come from, so that we can
 430          * find our way backwards if we want to break a cycle. We use
 431          * a special marker for the beginning: we point to
 432          * ourselves. */
 433         j->marker = from ? from : j;
 434         j->generation = generation;
 435
 436         /* We assume that the dependencies are bidirectional, and
 437          * hence can ignore UNIT_AFTER */
 438         HASHMAP_FOREACH_KEY(v, u, j->unit->dependencies[UNIT_BEFORE], i) {
 439                 Job *o;
 440
 441                 /* Is there a job for this unit? */
 442                 o = hashmap_get(tr->jobs, u);
 443                 if (!o) {
 444                         /* Ok, there is no job for this in the
 445                          * transaction, but maybe there is already one
 446                          * running? */
 447                         o = u->job;
 448                         if (!o)
 449                                 continue;
 450                 }
 451
 452                 r = transaction_verify_order_one(tr, o, j, generation, e);
 453                 if (r < 0)
 454                         return r;
 455         }
 456
 457         /* Ok, let's backtrack, and remember that this entry is not on
 458          * our path anymore. */
 459         j->marker = NULL;
 460
 461         return 0;
 462 }
 463
 464 static int transaction_verify_order(Transaction *tr, unsigned *generation, sd_bus_error *e) {
 465         Job *j;
 466         int r;
 467         Iterator i;
 468         unsigned g;
 469
 470         assert(tr);
 471         assert(generation);
 472
 473         /* Check if the ordering graph is cyclic. If it is, try to fix
 474          * that up by dropping one of the jobs. */
 475
 476         g = (*generation)++;
 477
 478         HASHMAP_FOREACH(j, tr->jobs, i) {
 479                 r = transaction_verify_order_one(tr, j, NULL, g, e);
 480                 if (r < 0)
 481                         return r;
 482         }
 483
 484         return 0;
 485 }
 486
 487 static void transaction_collect_garbage(Transaction *tr) {
 488         Iterator i;
 489         Job *j;
 490
 491         assert(tr);
 492
 493         /* Drop jobs that are not required by any other job */
 494
 495 rescan:
 496         HASHMAP_FOREACH(j, tr->jobs, i) {
 497                 if (tr->anchor_job == j)
 498                         continue;
 499                 if (j->object_list) {
 500                         log_trace("Keeping job %s/%s because of %s/%s",
 501                                   j->unit->id, job_type_to_string(j->type),
 502                                   j->object_list->subject ? j->object_list->subject->unit->id : "root",
 503                                   j->object_list->subject ? job_type_to_string(j->object_list->subject->type) : "root");
 504                         continue;
 505                 }
 506
 507                 log_trace("Garbage collecting job %s/%s", j->unit->id, job_type_to_string(j->type));
 508                 transaction_delete_job(tr, j, true);
 509                 goto rescan;
 510         }
 511 }
 512
 513 static int transaction_is_destructive(Transaction *tr, JobMode mode, sd_bus_error *e) {
 514         Iterator i;
 515         Job *j;
 516
 517         assert(tr);
 518
 519         /* Checks whether applying this transaction means that
 520          * existing jobs would be replaced */
 521
 522         HASHMAP_FOREACH(j, tr->jobs, i) {
 523
 524                 /* Assume merged */
 525                 assert(!j->transaction_prev);
 526                 assert(!j->transaction_next);
 527
 528                 if (j->unit->job && (mode == JOB_FAIL || j->unit->job->irreversible) &&
 529                     job_type_is_conflicting(j->unit->job->type, j->type))
 530                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_IS_DESTRUCTIVE,
 531                                                  "Transaction for %s/%s is destructive (%s has '%s' job queued, but '%s' is included in transaction).",
 532                                                  tr->anchor_job->unit->id, job_type_to_string(tr->anchor_job->type),
 533                                                  j->unit->id, job_type_to_string(j->unit->job->type), job_type_to_string(j->type));
 534         }
 535
 536         return 0;
 537 }
 538
 539 static void transaction_minimize_impact(Transaction *tr) {
 540         Job *j;
 541         Iterator i;
 542
 543         assert(tr);
 544
 545         /* Drops all unnecessary jobs that reverse already active jobs
 546          * or that stop a running service. */
 547
 548 rescan:
 549         HASHMAP_FOREACH(j, tr->jobs, i) {
 550                 LIST_FOREACH(transaction, j, j) {
 551                         bool stops_running_service, changes_existing_job;
 552
 553                         /* If it matters, we shouldn't drop it */
 554                         if (j->matters_to_anchor)
 555                                 continue;
 556
 557                         /* Would this stop a running service?
 558                          * Would this change an existing job?
 559                          * If so, let's drop this entry */
 560
 561                         stops_running_service =
 562                                 j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 563
 564                         changes_existing_job =
 565                                 j->unit->job &&
 566                                 job_type_is_conflicting(j->type, j->unit->job->type);
 567
 568                         if (!stops_running_service && !changes_existing_job)
 569                                 continue;
 570
 571                         if (stops_running_service)
 572                                 log_unit_debug(j->unit,
 573                                                "%s/%s would stop a running service.",
 574                                                j->unit->id, job_type_to_string(j->type));
 575
 576                         if (changes_existing_job)
 577                                 log_unit_debug(j->unit,
 578                                                "%s/%s would change existing job.",
 579                                                j->unit->id, job_type_to_string(j->type));
 580
 581                         /* Ok, let's get rid of this */
 582                         log_unit_debug(j->unit,
 583                                        "Deleting %s/%s to minimize impact.",
 584                                        j->unit->id, job_type_to_string(j->type));
 585
 586                         transaction_delete_job(tr, j, true);
 587                         goto rescan;
 588                 }
 589         }
 590 }
 591
 592 static int transaction_apply(Transaction *tr, Manager *m, JobMode mode) {
 593         Iterator i;
 594         Job *j;
 595         int r;
 596
 597         /* Moves the transaction jobs to the set of active jobs */
 598
 599         if (IN_SET(mode, JOB_ISOLATE, JOB_FLUSH)) {
 600
 601                 /* When isolating first kill all installed jobs which
 602                  * aren't part of the new transaction */
 603                 HASHMAP_FOREACH(j, m->jobs, i) {
 604                         assert(j->installed);
 605
 606                         if (j->unit->ignore_on_isolate)
 607                                 continue;
 608
 609                         if (hashmap_get(tr->jobs, j->unit))
 610                                 continue;
 611
 612                         /* Not invalidating recursively. Avoids triggering
 613                          * OnFailure= actions of dependent jobs. Also avoids
 614                          * invalidating our iterator. */
 615                         job_finish_and_invalidate(j, JOB_CANCELED, false, false);
 616                 }
 617         }
 618
 619         HASHMAP_FOREACH(j, tr->jobs, i) {
 620                 /* Assume merged */
 621                 assert(!j->transaction_prev);
 622                 assert(!j->transaction_next);
 623
 624                 r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j);
 625                 if (r < 0)
 626                         goto rollback;
 627         }
 628
 629         while ((j = hashmap_steal_first(tr->jobs))) {
 630                 Job *installed_job;
 631
 632                 /* Clean the job dependencies */
 633                 transaction_unlink_job(tr, j, false);
 634
 635                 installed_job = job_install(j);
 636                 if (installed_job != j) {
 637                         /* j has been merged into a previously installed job */
 638                         if (tr->anchor_job == j)
 639                                 tr->anchor_job = installed_job;
 640                         hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 641                         job_free(j);
 642                         j = installed_job;
 643                 }
 644
 645                 job_add_to_run_queue(j);
 646                 job_add_to_dbus_queue(j);
 647                 job_start_timer(j, false);
 648                 job_shutdown_magic(j);
 649         }
 650
 651         return 0;
 652
 653 rollback:
 654
 655         HASHMAP_FOREACH(j, tr->jobs, i)
 656                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 657
 658         return r;
 659 }
 660
 661 int transaction_activate(Transaction *tr, Manager *m, JobMode mode, sd_bus_error *e) {
 662         Iterator i;
 663         Job *j;
 664         int r;
 665         unsigned generation = 1;
 666
 667         assert(tr);
 668
 669         /* This applies the changes recorded in tr->jobs to
 670          * the actual list of jobs, if possible. */
 671
 672         /* Reset the generation counter of all installed jobs. The detection of cycles
 673          * looks at installed jobs. If they had a non-zero generation from some previous
 674          * walk of the graph, the algorithm would break. */
 675         HASHMAP_FOREACH(j, m->jobs, i)
 676                 j->generation = 0;
 677
 678         /* First step: figure out which jobs matter */
 679         transaction_find_jobs_that_matter_to_anchor(tr->anchor_job, generation++);
 680
 681         /* Second step: Try not to stop any running services if
 682          * we don't have to. Don't try to reverse running
 683          * jobs if we don't have to. */
 684         if (mode == JOB_FAIL)
 685                 transaction_minimize_impact(tr);
 686
 687         /* Third step: Drop redundant jobs */
 688         transaction_drop_redundant(tr);
 689
 690         for (;;) {
 691                 /* Fourth step: Let's remove unneeded jobs that might
 692                  * be lurking. */
 693                 if (mode != JOB_ISOLATE)
 694                         transaction_collect_garbage(tr);
 695
 696                 /* Fifth step: verify order makes sense and correct
 697                  * cycles if necessary and possible */
 698                 r = transaction_verify_order(tr, &generation, e);
 699                 if (r >= 0)
 700                         break;
 701
 702                 if (r != -EAGAIN)
 703                         return log_warning_errno(r, "Requested transaction contains an unfixable cyclic ordering dependency: %s", bus_error_message(e, r));
 704
 705                 /* Let's see if the resulting transaction ordering
 706                  * graph is still cyclic... */
 707         }
 708
 709         for (;;) {
 710                 /* Sixth step: let's drop unmergeable entries if
 711                  * necessary and possible, merge entries we can
 712                  * merge */
 713                 r = transaction_merge_jobs(tr, e);
 714                 if (r >= 0)
 715                         break;
 716
 717                 if (r != -EAGAIN)
 718                         return log_warning_errno(r, "Requested transaction contains unmergeable jobs: %s", bus_error_message(e, r));
 719
 720                 /* Seventh step: an entry got dropped, let's garbage
 721                  * collect its dependencies. */
 722                 if (mode != JOB_ISOLATE)
 723                         transaction_collect_garbage(tr);
 724
 725                 /* Let's see if the resulting transaction still has
 726                  * unmergeable entries ... */
 727         }
 728
 729         /* Eights step: Drop redundant jobs again, if the merging now allows us to drop more. */
 730         transaction_drop_redundant(tr);
 731
 732         /* Ninth step: check whether we can actually apply this */
 733         r = transaction_is_destructive(tr, mode, e);
 734         if (r < 0)
 735                 return log_notice_errno(r, "Requested transaction contradicts existing jobs: %s", bus_error_message(e, r));
 736
 737         /* Tenth step: apply changes */
 738         r = transaction_apply(tr, m, mode);
 739         if (r < 0)
 740                 return log_warning_errno(r, "Failed to apply transaction: %m");
 741
 742         assert(hashmap_isempty(tr->jobs));
 743
 744         if (!hashmap_isempty(m->jobs)) {
 745                 /* Are there any jobs now? Then make sure we have the
 746                  * idle pipe around. We don't really care too much
 747                  * whether this works or not, as the idle pipe is a
 748                  * feature for cosmetics, not actually useful for
 749                  * anything beyond that. */
 750
 751                 if (m->idle_pipe[0] < 0 && m->idle_pipe[1] < 0 &&
 752                     m->idle_pipe[2] < 0 && m->idle_pipe[3] < 0) {
 753                         (void) pipe2(m->idle_pipe, O_NONBLOCK|O_CLOEXEC);
 754                         (void) pipe2(m->idle_pipe + 2, O_NONBLOCK|O_CLOEXEC);
 755                 }
 756         }
 757
 758         return 0;
 759 }
 760
 761 static Job* transaction_add_one_job(Transaction *tr, JobType type, Unit *unit, bool *is_new) {
 762         Job *j, *f;
 763
 764         assert(tr);
 765         assert(unit);
 766
 767         /* Looks for an existing prospective job and returns that. If
 768          * it doesn't exist it is created and added to the prospective
 769          * jobs list. */
 770
 771         f = hashmap_get(tr->jobs, unit);
 772
 773         LIST_FOREACH(transaction, j, f) {
 774                 assert(j->unit == unit);
 775
 776                 if (j->type == type) {
 777                         if (is_new)
 778                                 *is_new = false;
 779                         return j;
 780                 }
 781         }
 782
 783         j = job_new(unit, type);
 784         if (!j)
 785                 return NULL;
 786
 787         j->generation = 0;
 788         j->marker = NULL;
 789         j->matters_to_anchor = false;
 790         j->irreversible = tr->irreversible;
 791
 792         LIST_PREPEND(transaction, f, j);
 793
 794         if (hashmap_replace(tr->jobs, unit, f) < 0) {
 795                 LIST_REMOVE(transaction, f, j);
 796                 job_free(j);
 797                 return NULL;
 798         }
 799
 800         if (is_new)
 801                 *is_new = true;
 802
 803         log_trace("Added job %s/%s to transaction.", unit->id, job_type_to_string(type));
 804
 805         return j;
 806 }
 807
 808 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies) {
 809         assert(tr);
 810         assert(j);
 811
 812         if (j->transaction_prev)
 813                 j->transaction_prev->transaction_next = j->transaction_next;
 814         else if (j->transaction_next)
 815                 hashmap_replace(tr->jobs, j->unit, j->transaction_next);
 816         else
 817                 hashmap_remove_value(tr->jobs, j->unit, j);
 818
 819         if (j->transaction_next)
 820                 j->transaction_next->transaction_prev = j->transaction_prev;
 821
 822         j->transaction_prev = j->transaction_next = NULL;
 823
 824         while (j->subject_list)
 825                 job_dependency_free(j->subject_list);
 826
 827         while (j->object_list) {
 828                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 829
 830                 job_dependency_free(j->object_list);
 831
 832                 if (other && delete_dependencies) {
 833                         log_unit_debug(other->unit,
 834                                        "Deleting job %s/%s as dependency of job %s/%s",
 835                                        other->unit->id, job_type_to_string(other->type),
 836                                        j->unit->id, job_type_to_string(j->type));
 837                         transaction_delete_job(tr, other, delete_dependencies);
 838                 }
 839         }
 840 }
 841
 842 void transaction_add_propagate_reload_jobs(Transaction *tr, Unit *unit, Job *by, bool ignore_order, sd_bus_error *e) {
 843         Iterator i;
 844         JobType nt;
 845         Unit *dep;
 846         void *v;
 847         int r;
 848
 849         assert(tr);
 850         assert(unit);
 851
 852         HASHMAP_FOREACH_KEY(v, dep, unit->dependencies[UNIT_PROPAGATES_RELOAD_TO], i) {
 853                 nt = job_type_collapse(JOB_TRY_RELOAD, dep);
 854                 if (nt == JOB_NOP)
 855                         continue;
 856
 857                 r = transaction_add_job_and_dependencies(tr, nt, dep, by, false, false, false, ignore_order, e);
 858                 if (r < 0) {
 859                         log_unit_warning(dep,
 860                                          "Cannot add dependency reload job, ignoring: %s",
 861                                          bus_error_message(e, r));
 862                         sd_bus_error_free(e);
 863                 }
 864         }
 865 }
 866
 867 int transaction_add_job_and_dependencies(
 868                 Transaction *tr,
 869                 JobType type,
 870                 Unit *unit,
 871                 Job *by,
 872                 bool matters,
 873                 bool conflicts,
 874                 bool ignore_requirements,
 875                 bool ignore_order,
 876                 sd_bus_error *e) {
 877
 878         bool is_new;
 879         Iterator i;
 880         Unit *dep;
 881         Job *ret;
 882         void *v;
 883         int r;
 884
 885         assert(tr);
 886         assert(type < _JOB_TYPE_MAX);
 887         assert(type < _JOB_TYPE_MAX_IN_TRANSACTION);
 888         assert(unit);
 889
 890         /* Before adding jobs for this unit, let's ensure that its state has been loaded
 891          * This matters when jobs are spawned as part of coldplugging itself (see e. g. path_coldplug()).
 892          * This way, we "recursively" coldplug units, ensuring that we do not look at state of
 893          * not-yet-coldplugged units. */
 894         if (MANAGER_IS_RELOADING(unit->manager))
 895                 unit_coldplug(unit);
 896
 897         if (by)
 898                 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));
 899
 900         /* Safety check that the unit is a valid state, i.e. not in UNIT_STUB or UNIT_MERGED which should only be set
 901          * temporarily. */
 902         if (!IN_SET(unit->load_state, UNIT_LOADED, UNIT_ERROR, UNIT_NOT_FOUND, UNIT_BAD_SETTING, UNIT_MASKED))
 903                 return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED, "Unit %s is not loaded properly.", unit->id);
 904
 905         if (type != JOB_STOP) {
 906                 r = bus_unit_validate_load_state(unit, e);
 907                 if (r < 0)
 908                         return r;
 909         }
 910
 911         if (!unit_job_is_applicable(unit, type))
 912                 return sd_bus_error_setf(e, BUS_ERROR_JOB_TYPE_NOT_APPLICABLE,
 913                                          "Job type %s is not applicable for unit %s.",
 914                                          job_type_to_string(type), unit->id);
 915
 916         /* First add the job. */
 917         ret = transaction_add_one_job(tr, type, unit, &is_new);
 918         if (!ret)
 919                 return -ENOMEM;
 920
 921         ret->ignore_order = ret->ignore_order || ignore_order;
 922
 923         /* Then, add a link to the job. */
 924         if (by) {
 925                 if (!job_dependency_new(by, ret, matters, conflicts))
 926                         return -ENOMEM;
 927         } else {
 928                 /* If the job has no parent job, it is the anchor job. */
 929                 assert(!tr->anchor_job);
 930                 tr->anchor_job = ret;
 931         }
 932
 933         if (is_new && !ignore_requirements && type != JOB_NOP) {
 934                 Set *following;
 935
 936                 /* If we are following some other unit, make sure we
 937                  * add all dependencies of everybody following. */
 938                 if (unit_following_set(ret->unit, &following) > 0) {
 939                         SET_FOREACH(dep, following, i) {
 940                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, false, false, false, ignore_order, e);
 941                                 if (r < 0) {
 942                                         log_unit_full(dep,
 943                                                       r == -ERFKILL ? LOG_INFO : LOG_WARNING,
 944                                                       r, "Cannot add dependency job, ignoring: %s",
 945                                                       bus_error_message(e, r));
 946                                         sd_bus_error_free(e);
 947                                 }
 948                         }
 949
 950                         set_free(following);
 951                 }
 952
 953                 /* Finally, recursively add in all dependencies. */
 954                 if (IN_SET(type, JOB_START, JOB_RESTART)) {
 955                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_REQUIRES], i) {
 956                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, false, false, ignore_order, e);
 957                                 if (r < 0) {
 958                                         if (r != -EBADR) /* job type not applicable */
 959                                                 goto fail;
 960
 961                                         sd_bus_error_free(e);
 962                                 }
 963                         }
 964
 965                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_BINDS_TO], i) {
 966                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, false, false, ignore_order, e);
 967                                 if (r < 0) {
 968                                         if (r != -EBADR) /* job type not applicable */
 969                                                 goto fail;
 970
 971                                         sd_bus_error_free(e);
 972                                 }
 973                         }
 974
 975                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_WANTS], i) {
 976                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, false, false, false, ignore_order, e);
 977                                 if (r < 0) {
 978                                         /* unit masked, job type not applicable and unit not found are not considered as errors. */
 979                                         log_unit_full(dep,
 980                                                       IN_SET(r, -ERFKILL, -EBADR, -ENOENT) ? LOG_DEBUG : LOG_WARNING,
 981                                                       r, "Cannot add dependency job, ignoring: %s",
 982                                                       bus_error_message(e, r));
 983                                         sd_bus_error_free(e);
 984                                 }
 985                         }
 986
 987                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_REQUISITE], i) {
 988                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, true, false, false, ignore_order, e);
 989                                 if (r < 0) {
 990                                         if (r != -EBADR) /* job type not applicable */
 991                                                 goto fail;
 992
 993                                         sd_bus_error_free(e);
 994                                 }
 995                         }
 996
 997                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_CONFLICTS], i) {
 998                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, true, true, false, ignore_order, e);
 999                                 if (r < 0) {
1000                                         if (r != -EBADR) /* job type not applicable */
1001                                                 goto fail;
1002
1003                                         sd_bus_error_free(e);
1004                                 }
1005                         }
1006
1007                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_CONFLICTED_BY], i) {
1008                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, false, false, false, ignore_order, e);
1009                                 if (r < 0) {
1010                                         log_unit_warning(dep,
1011                                                          "Cannot add dependency job, ignoring: %s",
1012                                                          bus_error_message(e, r));
1013                                         sd_bus_error_free(e);
1014                                 }
1015                         }
1016
1017                 }
1018
1019                 if (IN_SET(type, JOB_STOP, JOB_RESTART)) {
1020                         static const UnitDependency propagate_deps[] = {
1021                                 UNIT_REQUIRED_BY,
1022                                 UNIT_REQUISITE_OF,
1023                                 UNIT_BOUND_BY,
1024                                 UNIT_CONSISTS_OF,
1025                         };
1026
1027                         JobType ptype;
1028                         unsigned j;
1029
1030                         /* We propagate STOP as STOP, but RESTART only
1031                          * as TRY_RESTART, in order not to start
1032                          * dependencies that are not around. */
1033                         ptype = type == JOB_RESTART ? JOB_TRY_RESTART : type;
1034
1035                         for (j = 0; j < ELEMENTSOF(propagate_deps); j++)
1036                                 HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[propagate_deps[j]], i) {
1037                                         JobType nt;
1038
1039                                         nt = job_type_collapse(ptype, dep);
1040                                         if (nt == JOB_NOP)
1041                                                 continue;
1042
1043                                         r = transaction_add_job_and_dependencies(tr, nt, dep, ret, true, false, false, ignore_order, e);
1044                                         if (r < 0) {
1045                                                 if (r != -EBADR) /* job type not applicable */
1046                                                         goto fail;
1047
1048                                                 sd_bus_error_free(e);
1049                                         }
1050                                 }
1051                 }
1052
1053                 if (type == JOB_RELOAD)
1054                         transaction_add_propagate_reload_jobs(tr, ret->unit, ret, ignore_order, e);
1055
1056                 /* JOB_VERIFY_ACTIVE requires no dependency handling */
1057         }
1058
1059         return 0;
1060
1061 fail:
1062         return r;
1063 }
1064
1065 int transaction_add_isolate_jobs(Transaction *tr, Manager *m) {
1066         Iterator i;
1067         Unit *u;
1068         char *k;
1069         int r;
1070
1071         assert(tr);
1072         assert(m);
1073
1074         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
1075
1076                 /* ignore aliases */
1077                 if (u->id != k)
1078                         continue;
1079
1080                 if (u->ignore_on_isolate)
1081                         continue;
1082
1083                 /* No need to stop inactive jobs */
1084                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(u)) && !u->job)
1085                         continue;
1086
1087                 /* Is there already something listed for this? */
1088                 if (hashmap_get(tr->jobs, u))
1089                         continue;
1090
1091                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, u, tr->anchor_job, true, false, false, false, NULL);
1092                 if (r < 0)
1093                         log_unit_warning_errno(u, r, "Cannot add isolate job, ignoring: %m");
1094         }
1095
1096         return 0;
1097 }
1098
1099 Transaction *transaction_new(bool irreversible) {
1100         Transaction *tr;
1101
1102         tr = new0(Transaction, 1);
1103         if (!tr)
1104                 return NULL;
1105
1106         tr->jobs = hashmap_new(NULL);
1107         if (!tr->jobs)
1108                 return mfree(tr);
1109
1110         tr->irreversible = irreversible;
1111
1112         return tr;
1113 }
1114
1115 void transaction_free(Transaction *tr) {
1116         assert(hashmap_isempty(tr->jobs));
1117         hashmap_free(tr->jobs);
1118         free(tr);
1119 }