src/core/transaction.c

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