src/core/transaction.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 Lennart Poettering
   6 ***/
   7
   8 #include <fcntl.h>
   9 #include <unistd.h>
  10
  11 #include "alloc-util.h"
  12 #include "bus-common-errors.h"
  13 #include "bus-error.h"
  14 #include "terminal-util.h"
  15 #include "transaction.h"
  16 #include "dbus-unit.h"
  17
  18 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies);
  19
  20 static void transaction_delete_job(Transaction *tr, Job *j, bool delete_dependencies) {
  21         assert(tr);
  22         assert(j);
  23
  24         /* Deletes one job from the transaction */
  25
  26         transaction_unlink_job(tr, j, delete_dependencies);
  27
  28         job_free(j);
  29 }
  30
  31 static void transaction_delete_unit(Transaction *tr, Unit *u) {
  32         Job *j;
  33
  34         /* Deletes all jobs associated with a certain unit from the
  35          * transaction */
  36
  37         while ((j = hashmap_get(tr->jobs, u)))
  38                 transaction_delete_job(tr, j, true);
  39 }
  40
  41 void transaction_abort(Transaction *tr) {
  42         Job *j;
  43
  44         assert(tr);
  45
  46         while ((j = hashmap_first(tr->jobs)))
  47                 transaction_delete_job(tr, j, false);
  48
  49         assert(hashmap_isempty(tr->jobs));
  50 }
  51
  52 static void transaction_find_jobs_that_matter_to_anchor(Job *j, unsigned generation) {
  53         JobDependency *l;
  54
  55         /* A recursive sweep through the graph that marks all units
  56          * that matter to the anchor job, i.e. are directly or
  57          * indirectly a dependency of the anchor job via paths that
  58          * are fully marked as mattering. */
  59
  60         j->matters_to_anchor = true;
  61         j->generation = generation;
  62
  63         LIST_FOREACH(subject, l, j->subject_list) {
  64
  65                 /* This link does not matter */
  66                 if (!l->matters)
  67                         continue;
  68
  69                 /* This unit has already been marked */
  70                 if (l->object->generation == generation)
  71                         continue;
  72
  73                 transaction_find_jobs_that_matter_to_anchor(l->object, generation);
  74         }
  75 }
  76
  77 static void transaction_merge_and_delete_job(Transaction *tr, Job *j, Job *other, JobType t) {
  78         JobDependency *l, *last;
  79
  80         assert(j);
  81         assert(other);
  82         assert(j->unit == other->unit);
  83         assert(!j->installed);
  84
  85         /* Merges 'other' into 'j' and then deletes 'other'. */
  86
  87         j->type = t;
  88         j->state = JOB_WAITING;
  89         j->irreversible = j->irreversible || other->irreversible;
  90         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
  91
  92         /* Patch us in as new owner of the JobDependency objects */
  93         last = NULL;
  94         LIST_FOREACH(subject, l, other->subject_list) {
  95                 assert(l->subject == other);
  96                 l->subject = j;
  97                 last = l;
  98         }
  99
 100         /* Merge both lists */
 101         if (last) {
 102                 last->subject_next = j->subject_list;
 103                 if (j->subject_list)
 104                         j->subject_list->subject_prev = last;
 105                 j->subject_list = other->subject_list;
 106         }
 107
 108         /* Patch us in as new owner of the JobDependency objects */
 109         last = NULL;
 110         LIST_FOREACH(object, l, other->object_list) {
 111                 assert(l->object == other);
 112                 l->object = j;
 113                 last = l;
 114         }
 115
 116         /* Merge both lists */
 117         if (last) {
 118                 last->object_next = j->object_list;
 119                 if (j->object_list)
 120                         j->object_list->object_prev = last;
 121                 j->object_list = other->object_list;
 122         }
 123
 124         /* Kill the other job */
 125         other->subject_list = NULL;
 126         other->object_list = NULL;
 127         transaction_delete_job(tr, other, true);
 128 }
 129
 130 _pure_ static bool job_is_conflicted_by(Job *j) {
 131         JobDependency *l;
 132
 133         assert(j);
 134
 135         /* Returns true if this job is pulled in by a least one
 136          * ConflictedBy dependency. */
 137
 138         LIST_FOREACH(object, l, j->object_list)
 139                 if (l->conflicts)
 140                         return true;
 141
 142         return false;
 143 }
 144
 145 static int delete_one_unmergeable_job(Transaction *tr, Job *j) {
 146         Job *k;
 147
 148         assert(j);
 149
 150         /* Tries to delete one item in the linked list
 151          * j->transaction_next->transaction_next->... that conflicts
 152          * with another one, in an attempt to make an inconsistent
 153          * transaction work. */
 154
 155         /* We rely here on the fact that if a merged with b does not
 156          * merge with c, either a or b merge with c neither */
 157         LIST_FOREACH(transaction, j, j)
 158                 LIST_FOREACH(transaction, k, j->transaction_next) {
 159                         Job *d;
 160
 161                         /* Is this one mergeable? Then skip it */
 162                         if (job_type_is_mergeable(j->type, k->type))
 163                                 continue;
 164
 165                         /* Ok, we found two that conflict, let's see if we can
 166                          * drop one of them */
 167                         if (!j->matters_to_anchor && !k->matters_to_anchor) {
 168
 169                                 /* Both jobs don't matter, so let's
 170                                  * find the one that is smarter to
 171                                  * remove. Let's think positive and
 172                                  * rather remove stops then starts --
 173                                  * except if something is being
 174                                  * stopped because it is conflicted by
 175                                  * another unit in which case we
 176                                  * rather remove the start. */
 177
 178                                 log_unit_debug(j->unit,
 179                                                "Looking at job %s/%s conflicted_by=%s",
 180                                                j->unit->id, job_type_to_string(j->type),
 181                                                yes_no(j->type == JOB_STOP && job_is_conflicted_by(j)));
 182                                 log_unit_debug(k->unit,
 183                                                "Looking at job %s/%s conflicted_by=%s",
 184                                                k->unit->id, job_type_to_string(k->type),
 185                                                yes_no(k->type == JOB_STOP && job_is_conflicted_by(k)));
 186
 187                                 if (j->type == JOB_STOP) {
 188
 189                                         if (job_is_conflicted_by(j))
 190                                                 d = k;
 191                                         else
 192                                                 d = j;
 193
 194                                 } else if (k->type == JOB_STOP) {
 195
 196                                         if (job_is_conflicted_by(k))
 197                                                 d = j;
 198                                         else
 199                                                 d = k;
 200                                 } else
 201                                         d = j;
 202
 203                         } else if (!j->matters_to_anchor)
 204                                 d = j;
 205                         else if (!k->matters_to_anchor)
 206                                 d = k;
 207                         else
 208                                 return -ENOEXEC;
 209
 210                         /* Ok, we can drop one, so let's do so. */
 211                         log_unit_debug(d->unit,
 212                                        "Fixing conflicting jobs %s/%s,%s/%s by deleting job %s/%s",
 213                                        j->unit->id, job_type_to_string(j->type),
 214                                        k->unit->id, job_type_to_string(k->type),
 215                                        d->unit->id, job_type_to_string(d->type));
 216                         transaction_delete_job(tr, d, true);
 217                         return 0;
 218                 }
 219
 220         return -EINVAL;
 221 }
 222
 223 static int transaction_merge_jobs(Transaction *tr, sd_bus_error *e) {
 224         Job *j;
 225         Iterator i;
 226         int r;
 227
 228         assert(tr);
 229
 230         /* First step, check whether any of the jobs for one specific
 231          * task conflict. If so, try to drop one of them. */
 232         HASHMAP_FOREACH(j, tr->jobs, i) {
 233                 JobType t;
 234                 Job *k;
 235
 236                 t = j->type;
 237                 LIST_FOREACH(transaction, k, j->transaction_next) {
 238                         if (job_type_merge_and_collapse(&t, k->type, j->unit) >= 0)
 239                                 continue;
 240
 241                         /* OK, we could not merge all jobs for this
 242                          * action. Let's see if we can get rid of one
 243                          * of them */
 244
 245                         r = delete_one_unmergeable_job(tr, j);
 246                         if (r >= 0)
 247                                 /* Ok, we managed to drop one, now
 248                                  * let's ask our callers to call us
 249                                  * again after garbage collecting */
 250                                 return -EAGAIN;
 251
 252                         /* We couldn't merge anything. Failure */
 253                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_JOBS_CONFLICTING,
 254                                                  "Transaction contains conflicting jobs '%s' and '%s' for %s. "
 255                                                  "Probably contradicting requirement dependencies configured.",
 256                                                  job_type_to_string(t),
 257                                                  job_type_to_string(k->type),
 258                                                  k->unit->id);
 259                 }
 260         }
 261
 262         /* Second step, merge the jobs. */
 263         HASHMAP_FOREACH(j, tr->jobs, i) {
 264                 JobType t = j->type;
 265                 Job *k;
 266
 267                 /* Merge all transaction jobs for j->unit */
 268                 LIST_FOREACH(transaction, k, j->transaction_next)
 269                         assert_se(job_type_merge_and_collapse(&t, k->type, j->unit) == 0);
 270
 271                 while ((k = j->transaction_next)) {
 272                         if (tr->anchor_job == k) {
 273                                 transaction_merge_and_delete_job(tr, k, j, t);
 274                                 j = k;
 275                         } else
 276                                 transaction_merge_and_delete_job(tr, j, k, t);
 277                 }
 278
 279                 assert(!j->transaction_next);
 280                 assert(!j->transaction_prev);
 281         }
 282
 283         return 0;
 284 }
 285
 286 static void transaction_drop_redundant(Transaction *tr) {
 287         Job *j;
 288         Iterator i;
 289
 290         /* Goes through the transaction and removes all jobs of the units
 291          * whose jobs are all noops. If not all of a unit's jobs are
 292          * redundant, they are kept. */
 293
 294         assert(tr);
 295
 296 rescan:
 297         HASHMAP_FOREACH(j, tr->jobs, i) {
 298                 Job *k;
 299
 300                 LIST_FOREACH(transaction, k, j) {
 301
 302                         if (tr->anchor_job == k ||
 303                             !job_type_is_redundant(k->type, unit_active_state(k->unit)) ||
 304                             (k->unit->job && job_type_is_conflicting(k->type, k->unit->job->type)))
 305                                 goto next_unit;
 306                 }
 307
 308                 /* log_debug("Found redundant job %s/%s, dropping.", j->unit->id, job_type_to_string(j->type)); */
 309                 transaction_delete_job(tr, j, false);
 310                 goto rescan;
 311         next_unit:;
 312         }
 313 }
 314
 315 _pure_ static bool unit_matters_to_anchor(Unit *u, Job *j) {
 316         assert(u);
 317         assert(!j->transaction_prev);
 318
 319         /* Checks whether at least one of the jobs for this unit
 320          * matters to the anchor. */
 321
 322         LIST_FOREACH(transaction, j, j)
 323                 if (j->matters_to_anchor)
 324                         return true;
 325
 326         return false;
 327 }
 328
 329 static char* merge_unit_ids(const char* unit_log_field, char **pairs) {
 330         char **unit_id, **job_type, *ans = NULL;
 331         size_t alloc = 0, size = 0, next;
 332
 333         STRV_FOREACH_PAIR(unit_id, job_type, pairs) {
 334                 next = strlen(unit_log_field) + strlen(*unit_id);
 335                 if (!GREEDY_REALLOC(ans, alloc, size + next + 1)) {
 336                         return mfree(ans);
 337                 }
 338
 339                 sprintf(ans + size, "%s%s", unit_log_field, *unit_id);
 340                 if (*(unit_id+1))
 341                         ans[size + next] =  '\n';
 342                 size += next + 1;
 343         }
 344
 345         return ans;
 346 }
 347
 348 static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsigned generation, sd_bus_error *e) {
 349         Iterator i;
 350         Unit *u;
 351         void *v;
 352         int r;
 353
 354         assert(tr);
 355         assert(j);
 356         assert(!j->transaction_prev);
 357
 358         /* Does a recursive sweep through the ordering graph, looking
 359          * for a cycle. If we find a cycle we try to break it. */
 360
 361         /* Have we seen this before? */
 362         if (j->generation == generation) {
 363                 Job *k, *delete = NULL;
 364                 _cleanup_free_ char **array = NULL, *unit_ids = NULL;
 365                 char **unit_id, **job_type;
 366
 367                 /* If the marker is NULL we have been here already and
 368                  * decided the job was loop-free from here. Hence
 369                  * shortcut things and return right-away. */
 370                 if (!j->marker)
 371                         return 0;
 372
 373                 /* So, the marker is not NULL and we already have been here. We have
 374                  * a cycle. Let's try to break it. We go backwards in our path and
 375                  * try to find a suitable job to remove. We use the marker to find
 376                  * our way back, since smart how we are we stored our way back in
 377                  * there. */
 378
 379                 for (k = from; k; k = ((k->generation == generation && k->marker != k) ? k->marker : NULL)) {
 380
 381                         /* For logging below */
 382                         if (strv_push_pair(&array, k->unit->id, (char*) job_type_to_string(k->type)) < 0)
 383                                 log_oom();
 384
 385                         if (!delete && hashmap_get(tr->jobs, k->unit) && !unit_matters_to_anchor(k->unit, k))
 386                                 /* Ok, we can drop this one, so let's do so. */
 387                                 delete = k;
 388
 389                         /* Check if this in fact was the beginning of the cycle */
 390                         if (k == j)
 391                                 break;
 392                 }
 393
 394                 unit_ids = merge_unit_ids(j->manager->unit_log_field, array); /* ignore error */
 395
 396                 STRV_FOREACH_PAIR(unit_id, job_type, array)
 397                         /* logging for j not k here to provide a consistent narrative */
 398                         log_struct(LOG_WARNING,
 399                                    "MESSAGE=%s: Found %s on %s/%s",
 400                                    j->unit->id,
 401                                    unit_id == array ? "ordering cycle" : "dependency",
 402                                    *unit_id, *job_type,
 403                                    unit_ids);
 404
 405                 if (delete) {
 406                         const char *status;
 407                         /* logging for j not k here to provide a consistent narrative */
 408                         log_struct(LOG_ERR,
 409                                    "MESSAGE=%s: Job %s/%s deleted to break ordering cycle starting with %s/%s",
 410                                    j->unit->id, delete->unit->id, job_type_to_string(delete->type),
 411                                    j->unit->id, job_type_to_string(j->type),
 412                                    unit_ids);
 413
 414                         if (log_get_show_color())
 415                                 status = ANSI_HIGHLIGHT_RED " SKIP " ANSI_NORMAL;
 416                         else
 417                                 status = " SKIP ";
 418
 419                         unit_status_printf(delete->unit, status,
 420                                            "Ordering cycle found, skipping %s");
 421                         transaction_delete_unit(tr, delete->unit);
 422                         return -EAGAIN;
 423                 }
 424
 425                 log_struct(LOG_ERR,
 426                            "MESSAGE=%s: Unable to break cycle starting with %s/%s",
 427                            j->unit->id, j->unit->id, job_type_to_string(j->type),
 428                            unit_ids);
 429
 430                 return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_ORDER_IS_CYCLIC,
 431                                          "Transaction order is cyclic. See system logs for details.");
 432         }
 433
 434         /* Make the marker point to where we come from, so that we can
 435          * find our way backwards if we want to break a cycle. We use
 436          * a special marker for the beginning: we point to
 437          * ourselves. */
 438         j->marker = from ? from : j;
 439         j->generation = generation;
 440
 441         /* We assume that the dependencies are bidirectional, and
 442          * hence can ignore UNIT_AFTER */
 443         HASHMAP_FOREACH_KEY(v, u, j->unit->dependencies[UNIT_BEFORE], i) {
 444                 Job *o;
 445
 446                 /* Is there a job for this unit? */
 447                 o = hashmap_get(tr->jobs, u);
 448                 if (!o) {
 449                         /* Ok, there is no job for this in the
 450                          * transaction, but maybe there is already one
 451                          * running? */
 452                         o = u->job;
 453                         if (!o)
 454                                 continue;
 455                 }
 456
 457                 r = transaction_verify_order_one(tr, o, j, generation, e);
 458                 if (r < 0)
 459                         return r;
 460         }
 461
 462         /* Ok, let's backtrack, and remember that this entry is not on
 463          * our path anymore. */
 464         j->marker = NULL;
 465
 466         return 0;
 467 }
 468
 469 static int transaction_verify_order(Transaction *tr, unsigned *generation, sd_bus_error *e) {
 470         Job *j;
 471         int r;
 472         Iterator i;
 473         unsigned g;
 474
 475         assert(tr);
 476         assert(generation);
 477
 478         /* Check if the ordering graph is cyclic. If it is, try to fix
 479          * that up by dropping one of the jobs. */
 480
 481         g = (*generation)++;
 482
 483         HASHMAP_FOREACH(j, tr->jobs, i) {
 484                 r = transaction_verify_order_one(tr, j, NULL, g, e);
 485                 if (r < 0)
 486                         return r;
 487         }
 488
 489         return 0;
 490 }
 491
 492 static void transaction_collect_garbage(Transaction *tr) {
 493         Iterator i;
 494         Job *j;
 495
 496         assert(tr);
 497
 498         /* Drop jobs that are not required by any other job */
 499
 500 rescan:
 501         HASHMAP_FOREACH(j, tr->jobs, i) {
 502                 if (tr->anchor_job == j || j->object_list) {
 503                         /* log_debug("Keeping job %s/%s because of %s/%s", */
 504                         /*           j->unit->id, job_type_to_string(j->type), */
 505                         /*           j->object_list->subject ? j->object_list->subject->unit->id : "root", */
 506                         /*           j->object_list->subject ? job_type_to_string(j->object_list->subject->type) : "root"); */
 507                         continue;
 508                 }
 509
 510                 /* log_debug("Garbage collecting job %s/%s", j->unit->id, job_type_to_string(j->type)); */
 511                 transaction_delete_job(tr, j, true);
 512                 goto rescan;
 513         }
 514 }
 515
 516 static int transaction_is_destructive(Transaction *tr, JobMode mode, sd_bus_error *e) {
 517         Iterator i;
 518         Job *j;
 519
 520         assert(tr);
 521
 522         /* Checks whether applying this transaction means that
 523          * existing jobs would be replaced */
 524
 525         HASHMAP_FOREACH(j, tr->jobs, i) {
 526
 527                 /* Assume merged */
 528                 assert(!j->transaction_prev);
 529                 assert(!j->transaction_next);
 530
 531                 if (j->unit->job && (mode == JOB_FAIL || j->unit->job->irreversible) &&
 532                     job_type_is_conflicting(j->unit->job->type, j->type))
 533                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_IS_DESTRUCTIVE,
 534                                                  "Transaction is destructive.");
 535         }
 536
 537         return 0;
 538 }
 539
 540 static void transaction_minimize_impact(Transaction *tr) {
 541         Job *j;
 542         Iterator i;
 543
 544         assert(tr);
 545
 546         /* Drops all unnecessary jobs that reverse already active jobs
 547          * or that stop a running service. */
 548
 549 rescan:
 550         HASHMAP_FOREACH(j, tr->jobs, i) {
 551                 LIST_FOREACH(transaction, j, j) {
 552                         bool stops_running_service, changes_existing_job;
 553
 554                         /* If it matters, we shouldn't drop it */
 555                         if (j->matters_to_anchor)
 556                                 continue;
 557
 558                         /* Would this stop a running service?
 559                          * Would this change an existing job?
 560                          * If so, let's drop this entry */
 561
 562                         stops_running_service =
 563                                 j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 564
 565                         changes_existing_job =
 566                                 j->unit->job &&
 567                                 job_type_is_conflicting(j->type, j->unit->job->type);
 568
 569                         if (!stops_running_service && !changes_existing_job)
 570                                 continue;
 571
 572                         if (stops_running_service)
 573                                 log_unit_debug(j->unit,
 574                                                "%s/%s would stop a running service.",
 575                                                j->unit->id, job_type_to_string(j->type));
 576
 577                         if (changes_existing_job)
 578                                 log_unit_debug(j->unit,
 579                                                "%s/%s would change existing job.",
 580                                                j->unit->id, job_type_to_string(j->type));
 581
 582                         /* Ok, let's get rid of this */
 583                         log_unit_debug(j->unit,
 584                                        "Deleting %s/%s to minimize impact.",
 585                                        j->unit->id, job_type_to_string(j->type));
 586
 587                         transaction_delete_job(tr, j, true);
 588                         goto rescan;
 589                 }
 590         }
 591 }
 592
 593 static int transaction_apply(Transaction *tr, Manager *m, JobMode mode) {
 594         Iterator i;
 595         Job *j;
 596         int r;
 597
 598         /* Moves the transaction jobs to the set of active jobs */
 599
 600         if (IN_SET(mode, JOB_ISOLATE, JOB_FLUSH)) {
 601
 602                 /* When isolating first kill all installed jobs which
 603                  * aren't part of the new transaction */
 604                 HASHMAP_FOREACH(j, m->jobs, i) {
 605                         assert(j->installed);
 606
 607                         if (j->unit->ignore_on_isolate)
 608                                 continue;
 609
 610                         if (hashmap_get(tr->jobs, j->unit))
 611                                 continue;
 612
 613                         /* Not invalidating recursively. Avoids triggering
 614                          * OnFailure= actions of dependent jobs. Also avoids
 615                          * invalidating our iterator. */
 616                         job_finish_and_invalidate(j, JOB_CANCELED, false, false);
 617                 }
 618         }
 619
 620         HASHMAP_FOREACH(j, tr->jobs, i) {
 621                 /* Assume merged */
 622                 assert(!j->transaction_prev);
 623                 assert(!j->transaction_next);
 624
 625                 r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j);
 626                 if (r < 0)
 627                         goto rollback;
 628         }
 629
 630         while ((j = hashmap_steal_first(tr->jobs))) {
 631                 Job *installed_job;
 632
 633                 /* Clean the job dependencies */
 634                 transaction_unlink_job(tr, j, false);
 635
 636                 installed_job = job_install(j);
 637                 if (installed_job != j) {
 638                         /* j has been merged into a previously installed job */
 639                         if (tr->anchor_job == j)
 640                                 tr->anchor_job = installed_job;
 641                         hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 642                         job_free(j);
 643                         j = installed_job;
 644                 }
 645
 646                 job_add_to_run_queue(j);
 647                 job_add_to_dbus_queue(j);
 648                 job_start_timer(j, false);
 649                 job_shutdown_magic(j);
 650         }
 651
 652         return 0;
 653
 654 rollback:
 655
 656         HASHMAP_FOREACH(j, tr->jobs, i)
 657                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 658
 659         return r;
 660 }
 661
 662 int transaction_activate(Transaction *tr, Manager *m, JobMode mode, sd_bus_error *e) {
 663         Iterator i;
 664         Job *j;
 665         int r;
 666         unsigned generation = 1;
 667
 668         assert(tr);
 669
 670         /* This applies the changes recorded in tr->jobs to
 671          * the actual list of jobs, if possible. */
 672
 673         /* Reset the generation counter of all installed jobs. The detection of cycles
 674          * looks at installed jobs. If they had a non-zero generation from some previous
 675          * walk of the graph, the algorithm would break. */
 676         HASHMAP_FOREACH(j, m->jobs, i)
 677                 j->generation = 0;
 678
 679         /* First step: figure out which jobs matter */
 680         transaction_find_jobs_that_matter_to_anchor(tr->anchor_job, generation++);
 681
 682         /* Second step: Try not to stop any running services if
 683          * we don't have to. Don't try to reverse running
 684          * jobs if we don't have to. */
 685         if (mode == JOB_FAIL)
 686                 transaction_minimize_impact(tr);
 687
 688         /* Third step: Drop redundant jobs */
 689         transaction_drop_redundant(tr);
 690
 691         for (;;) {
 692                 /* Fourth step: Let's remove unneeded jobs that might
 693                  * be lurking. */
 694                 if (mode != JOB_ISOLATE)
 695                         transaction_collect_garbage(tr);
 696
 697                 /* Fifth step: verify order makes sense and correct
 698                  * cycles if necessary and possible */
 699                 r = transaction_verify_order(tr, &generation, e);
 700                 if (r >= 0)
 701                         break;
 702
 703                 if (r != -EAGAIN) {
 704                         log_warning("Requested transaction contains an unfixable cyclic ordering dependency: %s", bus_error_message(e, r));
 705                         return r;
 706                 }
 707
 708                 /* Let's see if the resulting transaction ordering
 709                  * graph is still cyclic... */
 710         }
 711
 712         for (;;) {
 713                 /* Sixth step: let's drop unmergeable entries if
 714                  * necessary and possible, merge entries we can
 715                  * merge */
 716                 r = transaction_merge_jobs(tr, e);
 717                 if (r >= 0)
 718                         break;
 719
 720                 if (r != -EAGAIN) {
 721                         log_warning("Requested transaction contains unmergeable jobs: %s", bus_error_message(e, r));
 722                         return r;
 723                 }
 724
 725                 /* Seventh step: an entry got dropped, let's garbage
 726                  * collect its dependencies. */
 727                 if (mode != JOB_ISOLATE)
 728                         transaction_collect_garbage(tr);
 729
 730                 /* Let's see if the resulting transaction still has
 731                  * unmergeable entries ... */
 732         }
 733
 734         /* Eights step: Drop redundant jobs again, if the merging now allows us to drop more. */
 735         transaction_drop_redundant(tr);
 736
 737         /* Ninth step: check whether we can actually apply this */
 738         r = transaction_is_destructive(tr, mode, e);
 739         if (r < 0) {
 740                 log_notice("Requested transaction contradicts existing jobs: %s", bus_error_message(e, r));
 741                 return r;
 742         }
 743
 744         /* Tenth step: apply changes */
 745         r = transaction_apply(tr, m, mode);
 746         if (r < 0)
 747                 return log_warning_errno(r, "Failed to apply transaction: %m");
 748
 749         assert(hashmap_isempty(tr->jobs));
 750
 751         if (!hashmap_isempty(m->jobs)) {
 752                 /* Are there any jobs now? Then make sure we have the
 753                  * idle pipe around. We don't really care too much
 754                  * whether this works or not, as the idle pipe is a
 755                  * feature for cosmetics, not actually useful for
 756                  * anything beyond that. */
 757
 758                 if (m->idle_pipe[0] < 0 && m->idle_pipe[1] < 0 &&
 759                     m->idle_pipe[2] < 0 && m->idle_pipe[3] < 0) {
 760                         (void) pipe2(m->idle_pipe, O_NONBLOCK|O_CLOEXEC);
 761                         (void) pipe2(m->idle_pipe + 2, O_NONBLOCK|O_CLOEXEC);
 762                 }
 763         }
 764
 765         return 0;
 766 }
 767
 768 static Job* transaction_add_one_job(Transaction *tr, JobType type, Unit *unit, bool *is_new) {
 769         Job *j, *f;
 770
 771         assert(tr);
 772         assert(unit);
 773
 774         /* Looks for an existing prospective job and returns that. If
 775          * it doesn't exist it is created and added to the prospective
 776          * jobs list. */
 777
 778         f = hashmap_get(tr->jobs, unit);
 779
 780         LIST_FOREACH(transaction, j, f) {
 781                 assert(j->unit == unit);
 782
 783                 if (j->type == type) {
 784                         if (is_new)
 785                                 *is_new = false;
 786                         return j;
 787                 }
 788         }
 789
 790         j = job_new(unit, type);
 791         if (!j)
 792                 return NULL;
 793
 794         j->generation = 0;
 795         j->marker = NULL;
 796         j->matters_to_anchor = false;
 797         j->irreversible = tr->irreversible;
 798
 799         LIST_PREPEND(transaction, f, j);
 800
 801         if (hashmap_replace(tr->jobs, unit, f) < 0) {
 802                 LIST_REMOVE(transaction, f, j);
 803                 job_free(j);
 804                 return NULL;
 805         }
 806
 807         if (is_new)
 808                 *is_new = true;
 809
 810         /* log_debug("Added job %s/%s to transaction.", unit->id, job_type_to_string(type)); */
 811
 812         return j;
 813 }
 814
 815 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies) {
 816         assert(tr);
 817         assert(j);
 818
 819         if (j->transaction_prev)
 820                 j->transaction_prev->transaction_next = j->transaction_next;
 821         else if (j->transaction_next)
 822                 hashmap_replace(tr->jobs, j->unit, j->transaction_next);
 823         else
 824                 hashmap_remove_value(tr->jobs, j->unit, j);
 825
 826         if (j->transaction_next)
 827                 j->transaction_next->transaction_prev = j->transaction_prev;
 828
 829         j->transaction_prev = j->transaction_next = NULL;
 830
 831         while (j->subject_list)
 832                 job_dependency_free(j->subject_list);
 833
 834         while (j->object_list) {
 835                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 836
 837                 job_dependency_free(j->object_list);
 838
 839                 if (other && delete_dependencies) {
 840                         log_unit_debug(other->unit,
 841                                        "Deleting job %s/%s as dependency of job %s/%s",
 842                                        other->unit->id, job_type_to_string(other->type),
 843                                        j->unit->id, job_type_to_string(j->type));
 844                         transaction_delete_job(tr, other, delete_dependencies);
 845                 }
 846         }
 847 }
 848
 849 void transaction_add_propagate_reload_jobs(Transaction *tr, Unit *unit, Job *by, bool ignore_order, sd_bus_error *e) {
 850         Iterator i;
 851         JobType nt;
 852         Unit *dep;
 853         void *v;
 854         int r;
 855
 856         assert(tr);
 857         assert(unit);
 858
 859         HASHMAP_FOREACH_KEY(v, dep, unit->dependencies[UNIT_PROPAGATES_RELOAD_TO], i) {
 860                 nt = job_type_collapse(JOB_TRY_RELOAD, dep);
 861                 if (nt == JOB_NOP)
 862                         continue;
 863
 864                 r = transaction_add_job_and_dependencies(tr, nt, dep, by, false, false, false, ignore_order, e);
 865                 if (r < 0) {
 866                         log_unit_warning(dep,
 867                                          "Cannot add dependency reload job, ignoring: %s",
 868                                          bus_error_message(e, r));
 869                         sd_bus_error_free(e);
 870                 }
 871         }
 872 }
 873
 874 int transaction_add_job_and_dependencies(
 875                 Transaction *tr,
 876                 JobType type,
 877                 Unit *unit,
 878                 Job *by,
 879                 bool matters,
 880                 bool conflicts,
 881                 bool ignore_requirements,
 882                 bool ignore_order,
 883                 sd_bus_error *e) {
 884
 885         bool is_new;
 886         Iterator i;
 887         Unit *dep;
 888         Job *ret;
 889         void *v;
 890         int r;
 891
 892         assert(tr);
 893         assert(type < _JOB_TYPE_MAX);
 894         assert(type < _JOB_TYPE_MAX_IN_TRANSACTION);
 895         assert(unit);
 896
 897         /* Before adding jobs for this unit, let's ensure that its state has been loaded
 898          * This matters when jobs are spawned as part of coldplugging itself (see e. g. path_coldplug()).
 899          * This way, we "recursively" coldplug units, ensuring that we do not look at state of
 900          * not-yet-coldplugged units. */
 901         if (MANAGER_IS_RELOADING(unit->manager))
 902                 unit_coldplug(unit);
 903
 904         /* log_debug("Pulling in %s/%s from %s/%s", */
 905         /*           unit->id, job_type_to_string(type), */
 906         /*           by ? by->unit->id : "NA", */
 907         /*           by ? job_type_to_string(by->type) : "NA"); */
 908
 909         if (!IN_SET(unit->load_state, UNIT_LOADED, UNIT_ERROR, UNIT_NOT_FOUND, UNIT_MASKED))
 910                 return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED, "Unit %s is not loaded properly.", unit->id);
 911
 912         if (type != JOB_STOP) {
 913                 r = bus_unit_check_load_state(unit, e);
 914                 if (r < 0)
 915                         return r;
 916         }
 917
 918         if (!unit_job_is_applicable(unit, type))
 919                 return sd_bus_error_setf(e, BUS_ERROR_JOB_TYPE_NOT_APPLICABLE,
 920                                          "Job type %s is not applicable for unit %s.",
 921                                          job_type_to_string(type), unit->id);
 922
 923         /* First add the job. */
 924         ret = transaction_add_one_job(tr, type, unit, &is_new);
 925         if (!ret)
 926                 return -ENOMEM;
 927
 928         ret->ignore_order = ret->ignore_order || ignore_order;
 929
 930         /* Then, add a link to the job. */
 931         if (by) {
 932                 if (!job_dependency_new(by, ret, matters, conflicts))
 933                         return -ENOMEM;
 934         } else {
 935                 /* If the job has no parent job, it is the anchor job. */
 936                 assert(!tr->anchor_job);
 937                 tr->anchor_job = ret;
 938         }
 939
 940         if (is_new && !ignore_requirements && type != JOB_NOP) {
 941                 Set *following;
 942
 943                 /* If we are following some other unit, make sure we
 944                  * add all dependencies of everybody following. */
 945                 if (unit_following_set(ret->unit, &following) > 0) {
 946                         SET_FOREACH(dep, following, i) {
 947                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, false, false, false, ignore_order, e);
 948                                 if (r < 0) {
 949                                         log_unit_full(dep,
 950                                                       r == -ERFKILL ? LOG_INFO : LOG_WARNING,
 951                                                       r, "Cannot add dependency job, ignoring: %s",
 952                                                       bus_error_message(e, r));
 953                                         sd_bus_error_free(e);
 954                                 }
 955                         }
 956
 957                         set_free(following);
 958                 }
 959
 960                 /* Finally, recursively add in all dependencies. */
 961                 if (IN_SET(type, JOB_START, JOB_RESTART)) {
 962                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_REQUIRES], i) {
 963                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, false, false, ignore_order, e);
 964                                 if (r < 0) {
 965                                         if (r != -EBADR) /* job type not applicable */
 966                                                 goto fail;
 967
 968                                         sd_bus_error_free(e);
 969                                 }
 970                         }
 971
 972                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_BINDS_TO], i) {
 973                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, false, false, ignore_order, e);
 974                                 if (r < 0) {
 975                                         if (r != -EBADR) /* job type not applicable */
 976                                                 goto fail;
 977
 978                                         sd_bus_error_free(e);
 979                                 }
 980                         }
 981
 982                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_WANTS], i) {
 983                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, false, false, false, ignore_order, e);
 984                                 if (r < 0) {
 985                                         /* unit masked, job type not applicable and unit not found are not considered as errors. */
 986                                         log_unit_full(dep,
 987                                                       IN_SET(r, -ERFKILL, -EBADR, -ENOENT) ? LOG_DEBUG : LOG_WARNING,
 988                                                       r, "Cannot add dependency job, ignoring: %s",
 989                                                       bus_error_message(e, r));
 990                                         sd_bus_error_free(e);
 991                                 }
 992                         }
 993
 994                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_REQUISITE], i) {
 995                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, true, false, false, ignore_order, e);
 996                                 if (r < 0) {
 997                                         if (r != -EBADR) /* job type not applicable */
 998                                                 goto fail;
 999
1000                                         sd_bus_error_free(e);
1001                                 }
1002                         }
1003
1004                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_CONFLICTS], i) {
1005                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, true, true, false, ignore_order, e);
1006                                 if (r < 0) {
1007                                         if (r != -EBADR) /* job type not applicable */
1008                                                 goto fail;
1009
1010                                         sd_bus_error_free(e);
1011                                 }
1012                         }
1013
1014                         HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[UNIT_CONFLICTED_BY], i) {
1015                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, false, false, false, ignore_order, e);
1016                                 if (r < 0) {
1017                                         log_unit_warning(dep,
1018                                                          "Cannot add dependency job, ignoring: %s",
1019                                                          bus_error_message(e, r));
1020                                         sd_bus_error_free(e);
1021                                 }
1022                         }
1023
1024                 }
1025
1026                 if (IN_SET(type, JOB_STOP, JOB_RESTART)) {
1027                         static const UnitDependency propagate_deps[] = {
1028                                 UNIT_REQUIRED_BY,
1029                                 UNIT_REQUISITE_OF,
1030                                 UNIT_BOUND_BY,
1031                                 UNIT_CONSISTS_OF,
1032                         };
1033
1034                         JobType ptype;
1035                         unsigned j;
1036
1037                         /* We propagate STOP as STOP, but RESTART only
1038                          * as TRY_RESTART, in order not to start
1039                          * dependencies that are not around. */
1040                         ptype = type == JOB_RESTART ? JOB_TRY_RESTART : type;
1041
1042                         for (j = 0; j < ELEMENTSOF(propagate_deps); j++)
1043                                 HASHMAP_FOREACH_KEY(v, dep, ret->unit->dependencies[propagate_deps[j]], i) {
1044                                         JobType nt;
1045
1046                                         nt = job_type_collapse(ptype, dep);
1047                                         if (nt == JOB_NOP)
1048                                                 continue;
1049
1050                                         r = transaction_add_job_and_dependencies(tr, nt, dep, ret, true, false, false, ignore_order, e);
1051                                         if (r < 0) {
1052                                                 if (r != -EBADR) /* job type not applicable */
1053                                                         goto fail;
1054
1055                                                 sd_bus_error_free(e);
1056                                         }
1057                                 }
1058                 }
1059
1060                 if (type == JOB_RELOAD)
1061                         transaction_add_propagate_reload_jobs(tr, ret->unit, ret, ignore_order, e);
1062
1063                 /* JOB_VERIFY_STARTED require no dependency handling */
1064         }
1065
1066         return 0;
1067
1068 fail:
1069         return r;
1070 }
1071
1072 int transaction_add_isolate_jobs(Transaction *tr, Manager *m) {
1073         Iterator i;
1074         Unit *u;
1075         char *k;
1076         int r;
1077
1078         assert(tr);
1079         assert(m);
1080
1081         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
1082
1083                 /* ignore aliases */
1084                 if (u->id != k)
1085                         continue;
1086
1087                 if (u->ignore_on_isolate)
1088                         continue;
1089
1090                 /* No need to stop inactive jobs */
1091                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(u)) && !u->job)
1092                         continue;
1093
1094                 /* Is there already something listed for this? */
1095                 if (hashmap_get(tr->jobs, u))
1096                         continue;
1097
1098                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, u, tr->anchor_job, true, false, false, false, NULL);
1099                 if (r < 0)
1100                         log_unit_warning_errno(u, r, "Cannot add isolate job, ignoring: %m");
1101         }
1102
1103         return 0;
1104 }
1105
1106 Transaction *transaction_new(bool irreversible) {
1107         Transaction *tr;
1108
1109         tr = new0(Transaction, 1);
1110         if (!tr)
1111                 return NULL;
1112
1113         tr->jobs = hashmap_new(NULL);
1114         if (!tr->jobs)
1115                 return mfree(tr);
1116
1117         tr->irreversible = irreversible;
1118
1119         return tr;
1120 }
1121
1122 void transaction_free(Transaction *tr) {
1123         assert(hashmap_isempty(tr->jobs));
1124         hashmap_free(tr->jobs);
1125         free(tr);
1126 }