src/core/transaction.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <unistd.h>
  23 #include <fcntl.h>
  24
  25 #include "bus-common-errors.h"
  26 #include "bus-error.h"
  27 #include "transaction.h"
  28 #include "terminal-util.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->override = j->override || other->override;
 102         j->irreversible = j->irreversible || other->irreversible;
 103
 104         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
 105
 106         /* Patch us in as new owner of the JobDependency objects */
 107         last = NULL;
 108         LIST_FOREACH(subject, l, other->subject_list) {
 109                 assert(l->subject == other);
 110                 l->subject = j;
 111                 last = l;
 112         }
 113
 114         /* Merge both lists */
 115         if (last) {
 116                 last->subject_next = j->subject_list;
 117                 if (j->subject_list)
 118                         j->subject_list->subject_prev = last;
 119                 j->subject_list = other->subject_list;
 120         }
 121
 122         /* Patch us in as new owner of the JobDependency objects */
 123         last = NULL;
 124         LIST_FOREACH(object, l, other->object_list) {
 125                 assert(l->object == other);
 126                 l->object = j;
 127                 last = l;
 128         }
 129
 130         /* Merge both lists */
 131         if (last) {
 132                 last->object_next = j->object_list;
 133                 if (j->object_list)
 134                         j->object_list->object_prev = last;
 135                 j->object_list = other->object_list;
 136         }
 137
 138         /* Kill the other job */
 139         other->subject_list = NULL;
 140         other->object_list = NULL;
 141         transaction_delete_job(tr, other, true);
 142 }
 143
 144 _pure_ static bool job_is_conflicted_by(Job *j) {
 145         JobDependency *l;
 146
 147         assert(j);
 148
 149         /* Returns true if this job is pulled in by a least one
 150          * ConflictedBy dependency. */
 151
 152         LIST_FOREACH(object, l, j->object_list)
 153                 if (l->conflicts)
 154                         return true;
 155
 156         return false;
 157 }
 158
 159 static int delete_one_unmergeable_job(Transaction *tr, Job *j) {
 160         Job *k;
 161
 162         assert(j);
 163
 164         /* Tries to delete one item in the linked list
 165          * j->transaction_next->transaction_next->... that conflicts
 166          * with another one, in an attempt to make an inconsistent
 167          * transaction work. */
 168
 169         /* We rely here on the fact that if a merged with b does not
 170          * merge with c, either a or b merge with c neither */
 171         LIST_FOREACH(transaction, j, j)
 172                 LIST_FOREACH(transaction, k, j->transaction_next) {
 173                         Job *d;
 174
 175                         /* Is this one mergeable? Then skip it */
 176                         if (job_type_is_mergeable(j->type, k->type))
 177                                 continue;
 178
 179                         /* Ok, we found two that conflict, let's see if we can
 180                          * drop one of them */
 181                         if (!j->matters_to_anchor && !k->matters_to_anchor) {
 182
 183                                 /* Both jobs don't matter, so let's
 184                                  * find the one that is smarter to
 185                                  * remove. Let's think positive and
 186                                  * rather remove stops then starts --
 187                                  * except if something is being
 188                                  * stopped because it is conflicted by
 189                                  * another unit in which case we
 190                                  * rather remove the start. */
 191
 192                                 log_unit_debug(j->unit,
 193                                                "Looking at job %s/%s conflicted_by=%s",
 194                                                j->unit->id, job_type_to_string(j->type),
 195                                                yes_no(j->type == JOB_STOP && job_is_conflicted_by(j)));
 196                                 log_unit_debug(k->unit,
 197                                                "Looking at job %s/%s conflicted_by=%s",
 198                                                k->unit->id, job_type_to_string(k->type),
 199                                                yes_no(k->type == JOB_STOP && job_is_conflicted_by(k)));
 200
 201                                 if (j->type == JOB_STOP) {
 202
 203                                         if (job_is_conflicted_by(j))
 204                                                 d = k;
 205                                         else
 206                                                 d = j;
 207
 208                                 } else if (k->type == JOB_STOP) {
 209
 210                                         if (job_is_conflicted_by(k))
 211                                                 d = j;
 212                                         else
 213                                                 d = k;
 214                                 } else
 215                                         d = j;
 216
 217                         } else if (!j->matters_to_anchor)
 218                                 d = j;
 219                         else if (!k->matters_to_anchor)
 220                                 d = k;
 221                         else
 222                                 return -ENOEXEC;
 223
 224                         /* Ok, we can drop one, so let's do so. */
 225                         log_unit_debug(d->unit,
 226                                        "Fixing conflicting jobs %s/%s,%s/%s by deleting job %s/%s",
 227                                        j->unit->id, job_type_to_string(j->type),
 228                                        k->unit->id, job_type_to_string(k->type),
 229                                        d->unit->id, job_type_to_string(d->type));
 230                         transaction_delete_job(tr, d, true);
 231                         return 0;
 232                 }
 233
 234         return -EINVAL;
 235 }
 236
 237 static int transaction_merge_jobs(Transaction *tr, sd_bus_error *e) {
 238         Job *j;
 239         Iterator i;
 240         int r;
 241
 242         assert(tr);
 243
 244         /* First step, check whether any of the jobs for one specific
 245          * task conflict. If so, try to drop one of them. */
 246         HASHMAP_FOREACH(j, tr->jobs, i) {
 247                 JobType t;
 248                 Job *k;
 249
 250                 t = j->type;
 251                 LIST_FOREACH(transaction, k, j->transaction_next) {
 252                         if (job_type_merge_and_collapse(&t, k->type, j->unit) >= 0)
 253                                 continue;
 254
 255                         /* OK, we could not merge all jobs for this
 256                          * action. Let's see if we can get rid of one
 257                          * of them */
 258
 259                         r = delete_one_unmergeable_job(tr, j);
 260                         if (r >= 0)
 261                                 /* Ok, we managed to drop one, now
 262                                  * let's ask our callers to call us
 263                                  * again after garbage collecting */
 264                                 return -EAGAIN;
 265
 266                         /* We couldn't merge anything. Failure */
 267                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_JOBS_CONFLICTING,
 268                                                  "Transaction contains conflicting jobs '%s' and '%s' for %s. "
 269                                                  "Probably contradicting requirement dependencies configured.",
 270                                                  job_type_to_string(t),
 271                                                  job_type_to_string(k->type),
 272                                                  k->unit->id);
 273                 }
 274         }
 275
 276         /* Second step, merge the jobs. */
 277         HASHMAP_FOREACH(j, tr->jobs, i) {
 278                 JobType t = j->type;
 279                 Job *k;
 280
 281                 /* Merge all transaction jobs for j->unit */
 282                 LIST_FOREACH(transaction, k, j->transaction_next)
 283                         assert_se(job_type_merge_and_collapse(&t, k->type, j->unit) == 0);
 284
 285                 while ((k = j->transaction_next)) {
 286                         if (tr->anchor_job == k) {
 287                                 transaction_merge_and_delete_job(tr, k, j, t);
 288                                 j = k;
 289                         } else
 290                                 transaction_merge_and_delete_job(tr, j, k, t);
 291                 }
 292
 293                 assert(!j->transaction_next);
 294                 assert(!j->transaction_prev);
 295         }
 296
 297         return 0;
 298 }
 299
 300 static void transaction_drop_redundant(Transaction *tr) {
 301         Job *j;
 302         Iterator i;
 303
 304         /* Goes through the transaction and removes all jobs of the units
 305          * whose jobs are all noops. If not all of a unit's jobs are
 306          * redundant, they are kept. */
 307
 308         assert(tr);
 309
 310 rescan:
 311         HASHMAP_FOREACH(j, tr->jobs, i) {
 312                 Job *k;
 313
 314                 LIST_FOREACH(transaction, k, j) {
 315
 316                         if (tr->anchor_job == k ||
 317                             !job_type_is_redundant(k->type, unit_active_state(k->unit)) ||
 318                             (k->unit->job && job_type_is_conflicting(k->type, k->unit->job->type)))
 319                                 goto next_unit;
 320                 }
 321
 322                 /* log_debug("Found redundant job %s/%s, dropping.", j->unit->id, job_type_to_string(j->type)); */
 323                 transaction_delete_job(tr, j, false);
 324                 goto rescan;
 325         next_unit:;
 326         }
 327 }
 328
 329 _pure_ static bool unit_matters_to_anchor(Unit *u, Job *j) {
 330         assert(u);
 331         assert(!j->transaction_prev);
 332
 333         /* Checks whether at least one of the jobs for this unit
 334          * matters to the anchor. */
 335
 336         LIST_FOREACH(transaction, j, j)
 337                 if (j->matters_to_anchor)
 338                         return true;
 339
 340         return false;
 341 }
 342
 343 static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsigned generation, sd_bus_error *e) {
 344         Iterator i;
 345         Unit *u;
 346         int r;
 347
 348         assert(tr);
 349         assert(j);
 350         assert(!j->transaction_prev);
 351
 352         /* Does a recursive sweep through the ordering graph, looking
 353          * for a cycle. If we find a cycle we try to break it. */
 354
 355         /* Have we seen this before? */
 356         if (j->generation == generation) {
 357                 Job *k, *delete;
 358
 359                 /* If the marker is NULL we have been here already and
 360                  * decided the job was loop-free from here. Hence
 361                  * shortcut things and return right-away. */
 362                 if (!j->marker)
 363                         return 0;
 364
 365                 /* So, the marker is not NULL and we already have been
 366                  * here. We have a cycle. Let's try to break it. We go
 367                  * backwards in our path and try to find a suitable
 368                  * job to remove. We use the marker to find our way
 369                  * back, since smart how we are we stored our way back
 370                  * in there. */
 371                 log_unit_warning(j->unit,
 372                                  "Found ordering cycle on %s/%s",
 373                                  j->unit->id, job_type_to_string(j->type));
 374
 375                 delete = NULL;
 376                 for (k = from; k; k = ((k->generation == generation && k->marker != k) ? k->marker : NULL)) {
 377
 378                         /* logging for j not k here here to provide consistent narrative */
 379                         log_unit_warning(j->unit,
 380                                          "Found dependency on %s/%s",
 381                                          k->unit->id, job_type_to_string(k->type));
 382
 383                         if (!delete && hashmap_get(tr->jobs, k->unit) &&
 384                             !unit_matters_to_anchor(k->unit, k)) {
 385                                 /* Ok, we can drop this one, so let's
 386                                  * do so. */
 387                                 delete = k;
 388                         }
 389
 390                         /* Check if this in fact was the beginning of
 391                          * the cycle */
 392                         if (k == j)
 393                                 break;
 394                 }
 395
 396
 397                 if (delete) {
 398                         /* logging for j not k here here to provide consistent narrative */
 399                         log_unit_warning(j->unit,
 400                                          "Breaking ordering cycle by deleting job %s/%s",
 401                                          delete->unit->id, job_type_to_string(delete->type));
 402                         log_unit_error(delete->unit,
 403                                        "Job %s/%s deleted to break ordering cycle starting with %s/%s",
 404                                        delete->unit->id, job_type_to_string(delete->type),
 405                                        j->unit->id, job_type_to_string(j->type));
 406                         unit_status_printf(delete->unit, ANSI_HIGHLIGHT_RED_ON " SKIP " ANSI_HIGHLIGHT_OFF,
 407                                            "Ordering cycle found, skipping %s");
 408                         transaction_delete_unit(tr, delete->unit);
 409                         return -EAGAIN;
 410                 }
 411
 412                 log_error("Unable to break cycle");
 413
 414                 return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_ORDER_IS_CYCLIC,
 415                                          "Transaction order is cyclic. See system logs for details.");
 416         }
 417
 418         /* Make the marker point to where we come from, so that we can
 419          * find our way backwards if we want to break a cycle. We use
 420          * a special marker for the beginning: we point to
 421          * ourselves. */
 422         j->marker = from ? from : j;
 423         j->generation = generation;
 424
 425         /* We assume that the dependencies are bidirectional, and
 426          * hence can ignore UNIT_AFTER */
 427         SET_FOREACH(u, j->unit->dependencies[UNIT_BEFORE], i) {
 428                 Job *o;
 429
 430                 /* Is there a job for this unit? */
 431                 o = hashmap_get(tr->jobs, u);
 432                 if (!o) {
 433                         /* Ok, there is no job for this in the
 434                          * transaction, but maybe there is already one
 435                          * running? */
 436                         o = u->job;
 437                         if (!o)
 438                                 continue;
 439                 }
 440
 441                 r = transaction_verify_order_one(tr, o, j, generation, e);
 442                 if (r < 0)
 443                         return r;
 444         }
 445
 446         /* Ok, let's backtrack, and remember that this entry is not on
 447          * our path anymore. */
 448         j->marker = NULL;
 449
 450         return 0;
 451 }
 452
 453 static int transaction_verify_order(Transaction *tr, unsigned *generation, sd_bus_error *e) {
 454         Job *j;
 455         int r;
 456         Iterator i;
 457         unsigned g;
 458
 459         assert(tr);
 460         assert(generation);
 461
 462         /* Check if the ordering graph is cyclic. If it is, try to fix
 463          * that up by dropping one of the jobs. */
 464
 465         g = (*generation)++;
 466
 467         HASHMAP_FOREACH(j, tr->jobs, i)
 468                 if ((r = transaction_verify_order_one(tr, j, NULL, g, e)) < 0)
 469                         return r;
 470
 471         return 0;
 472 }
 473
 474 static void transaction_collect_garbage(Transaction *tr) {
 475         Iterator i;
 476         Job *j;
 477
 478         assert(tr);
 479
 480         /* Drop jobs that are not required by any other job */
 481
 482 rescan:
 483         HASHMAP_FOREACH(j, tr->jobs, i) {
 484                 if (tr->anchor_job == j || j->object_list) {
 485                         /* log_debug("Keeping job %s/%s because of %s/%s", */
 486                         /*           j->unit->id, job_type_to_string(j->type), */
 487                         /*           j->object_list->subject ? j->object_list->subject->unit->id : "root", */
 488                         /*           j->object_list->subject ? job_type_to_string(j->object_list->subject->type) : "root"); */
 489                         continue;
 490                 }
 491
 492                 /* log_debug("Garbage collecting job %s/%s", j->unit->id, job_type_to_string(j->type)); */
 493                 transaction_delete_job(tr, j, true);
 494                 goto rescan;
 495         }
 496 }
 497
 498 static int transaction_is_destructive(Transaction *tr, JobMode mode, sd_bus_error *e) {
 499         Iterator i;
 500         Job *j;
 501
 502         assert(tr);
 503
 504         /* Checks whether applying this transaction means that
 505          * existing jobs would be replaced */
 506
 507         HASHMAP_FOREACH(j, tr->jobs, i) {
 508
 509                 /* Assume merged */
 510                 assert(!j->transaction_prev);
 511                 assert(!j->transaction_next);
 512
 513                 if (j->unit->job && (mode == JOB_FAIL || j->unit->job->irreversible) &&
 514                     job_type_is_conflicting(j->unit->job->type, j->type))
 515                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_IS_DESTRUCTIVE,
 516                                                  "Transaction is destructive.");
 517         }
 518
 519         return 0;
 520 }
 521
 522 static void transaction_minimize_impact(Transaction *tr) {
 523         Job *j;
 524         Iterator i;
 525
 526         assert(tr);
 527
 528         /* Drops all unnecessary jobs that reverse already active jobs
 529          * or that stop a running service. */
 530
 531 rescan:
 532         HASHMAP_FOREACH(j, tr->jobs, i) {
 533                 LIST_FOREACH(transaction, j, j) {
 534                         bool stops_running_service, changes_existing_job;
 535
 536                         /* If it matters, we shouldn't drop it */
 537                         if (j->matters_to_anchor)
 538                                 continue;
 539
 540                         /* Would this stop a running service?
 541                          * Would this change an existing job?
 542                          * If so, let's drop this entry */
 543
 544                         stops_running_service =
 545                                 j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 546
 547                         changes_existing_job =
 548                                 j->unit->job &&
 549                                 job_type_is_conflicting(j->type, j->unit->job->type);
 550
 551                         if (!stops_running_service && !changes_existing_job)
 552                                 continue;
 553
 554                         if (stops_running_service)
 555                                 log_unit_debug(j->unit,
 556                                                "%s/%s would stop a running service.",
 557                                                j->unit->id, job_type_to_string(j->type));
 558
 559                         if (changes_existing_job)
 560                                 log_unit_debug(j->unit,
 561                                                "%s/%s would change existing job.",
 562                                                j->unit->id, job_type_to_string(j->type));
 563
 564                         /* Ok, let's get rid of this */
 565                         log_unit_debug(j->unit,
 566                                        "Deleting %s/%s to minimize impact.",
 567                                        j->unit->id, job_type_to_string(j->type));
 568
 569                         transaction_delete_job(tr, j, true);
 570                         goto rescan;
 571                 }
 572         }
 573 }
 574
 575 static int transaction_apply(Transaction *tr, Manager *m, JobMode mode) {
 576         Iterator i;
 577         Job *j;
 578         int r;
 579
 580         /* Moves the transaction jobs to the set of active jobs */
 581
 582         if (mode == JOB_ISOLATE || mode == JOB_FLUSH) {
 583
 584                 /* When isolating first kill all installed jobs which
 585                  * aren't part of the new transaction */
 586                 HASHMAP_FOREACH(j, m->jobs, i) {
 587                         assert(j->installed);
 588
 589                         if (hashmap_get(tr->jobs, j->unit))
 590                                 continue;
 591
 592                         /* Not invalidating recursively. Avoids triggering
 593                          * OnFailure= actions of dependent jobs. Also avoids
 594                          * invalidating our iterator. */
 595                         job_finish_and_invalidate(j, JOB_CANCELED, false);
 596                 }
 597         }
 598
 599         HASHMAP_FOREACH(j, tr->jobs, i) {
 600                 /* Assume merged */
 601                 assert(!j->transaction_prev);
 602                 assert(!j->transaction_next);
 603
 604                 r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j);
 605                 if (r < 0)
 606                         goto rollback;
 607         }
 608
 609         while ((j = hashmap_steal_first(tr->jobs))) {
 610                 Job *installed_job;
 611
 612                 /* Clean the job dependencies */
 613                 transaction_unlink_job(tr, j, false);
 614
 615                 installed_job = job_install(j);
 616                 if (installed_job != j) {
 617                         /* j has been merged into a previously installed job */
 618                         if (tr->anchor_job == j)
 619                                 tr->anchor_job = installed_job;
 620                         hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 621                         job_free(j);
 622                         j = installed_job;
 623                 }
 624
 625                 job_add_to_run_queue(j);
 626                 job_add_to_dbus_queue(j);
 627                 job_start_timer(j);
 628                 job_shutdown_magic(j);
 629         }
 630
 631         return 0;
 632
 633 rollback:
 634
 635         HASHMAP_FOREACH(j, tr->jobs, i)
 636                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 637
 638         return r;
 639 }
 640
 641 int transaction_activate(Transaction *tr, Manager *m, JobMode mode, sd_bus_error *e) {
 642         Iterator i;
 643         Job *j;
 644         int r;
 645         unsigned generation = 1;
 646
 647         assert(tr);
 648
 649         /* This applies the changes recorded in tr->jobs to
 650          * the actual list of jobs, if possible. */
 651
 652         /* Reset the generation counter of all installed jobs. The detection of cycles
 653          * looks at installed jobs. If they had a non-zero generation from some previous
 654          * walk of the graph, the algorithm would break. */
 655         HASHMAP_FOREACH(j, m->jobs, i)
 656                 j->generation = 0;
 657
 658         /* First step: figure out which jobs matter */
 659         transaction_find_jobs_that_matter_to_anchor(tr->anchor_job, generation++);
 660
 661         /* Second step: Try not to stop any running services if
 662          * we don't have to. Don't try to reverse running
 663          * jobs if we don't have to. */
 664         if (mode == JOB_FAIL)
 665                 transaction_minimize_impact(tr);
 666
 667         /* Third step: Drop redundant jobs */
 668         transaction_drop_redundant(tr);
 669
 670         for (;;) {
 671                 /* Fourth step: Let's remove unneeded jobs that might
 672                  * be lurking. */
 673                 if (mode != JOB_ISOLATE)
 674                         transaction_collect_garbage(tr);
 675
 676                 /* Fifth step: verify order makes sense and correct
 677                  * cycles if necessary and possible */
 678                 r = transaction_verify_order(tr, &generation, e);
 679                 if (r >= 0)
 680                         break;
 681
 682                 if (r != -EAGAIN) {
 683                         log_warning("Requested transaction contains an unfixable cyclic ordering dependency: %s", bus_error_message(e, r));
 684                         return r;
 685                 }
 686
 687                 /* Let's see if the resulting transaction ordering
 688                  * graph is still cyclic... */
 689         }
 690
 691         for (;;) {
 692                 /* Sixth step: let's drop unmergeable entries if
 693                  * necessary and possible, merge entries we can
 694                  * merge */
 695                 r = transaction_merge_jobs(tr, e);
 696                 if (r >= 0)
 697                         break;
 698
 699                 if (r != -EAGAIN) {
 700                         log_warning("Requested transaction contains unmergeable jobs: %s", bus_error_message(e, r));
 701                         return r;
 702                 }
 703
 704                 /* Seventh step: an entry got dropped, let's garbage
 705                  * collect its dependencies. */
 706                 if (mode != JOB_ISOLATE)
 707                         transaction_collect_garbage(tr);
 708
 709                 /* Let's see if the resulting transaction still has
 710                  * unmergeable entries ... */
 711         }
 712
 713         /* Eights step: Drop redundant jobs again, if the merging now allows us to drop more. */
 714         transaction_drop_redundant(tr);
 715
 716         /* Ninth step: check whether we can actually apply this */
 717         r = transaction_is_destructive(tr, mode, e);
 718         if (r < 0) {
 719                 log_notice("Requested transaction contradicts existing jobs: %s", bus_error_message(e, r));
 720                 return r;
 721         }
 722
 723         /* Tenth step: apply changes */
 724         r = transaction_apply(tr, m, mode);
 725         if (r < 0)
 726                 return log_warning_errno(r, "Failed to apply transaction: %m");
 727
 728         assert(hashmap_isempty(tr->jobs));
 729
 730         if (!hashmap_isempty(m->jobs)) {
 731                 /* Are there any jobs now? Then make sure we have the
 732                  * idle pipe around. We don't really care too much
 733                  * whether this works or not, as the idle pipe is a
 734                  * feature for cosmetics, not actually useful for
 735                  * anything beyond that. */
 736
 737                 if (m->idle_pipe[0] < 0 && m->idle_pipe[1] < 0 &&
 738                     m->idle_pipe[2] < 0 && m->idle_pipe[3] < 0) {
 739                         pipe2(m->idle_pipe, O_NONBLOCK|O_CLOEXEC);
 740                         pipe2(m->idle_pipe + 2, O_NONBLOCK|O_CLOEXEC);
 741                 }
 742         }
 743
 744         return 0;
 745 }
 746
 747 static Job* transaction_add_one_job(Transaction *tr, JobType type, Unit *unit, bool override, bool *is_new) {
 748         Job *j, *f;
 749
 750         assert(tr);
 751         assert(unit);
 752
 753         /* Looks for an existing prospective job and returns that. If
 754          * it doesn't exist it is created and added to the prospective
 755          * jobs list. */
 756
 757         f = hashmap_get(tr->jobs, unit);
 758
 759         LIST_FOREACH(transaction, j, f) {
 760                 assert(j->unit == unit);
 761
 762                 if (j->type == type) {
 763                         if (is_new)
 764                                 *is_new = false;
 765                         return j;
 766                 }
 767         }
 768
 769         j = job_new(unit, type);
 770         if (!j)
 771                 return NULL;
 772
 773         j->generation = 0;
 774         j->marker = NULL;
 775         j->matters_to_anchor = false;
 776         j->override = override;
 777         j->irreversible = tr->irreversible;
 778
 779         LIST_PREPEND(transaction, f, j);
 780
 781         if (hashmap_replace(tr->jobs, unit, f) < 0) {
 782                 LIST_REMOVE(transaction, f, j);
 783                 job_free(j);
 784                 return NULL;
 785         }
 786
 787         if (is_new)
 788                 *is_new = true;
 789
 790         /* log_debug("Added job %s/%s to transaction.", unit->id, job_type_to_string(type)); */
 791
 792         return j;
 793 }
 794
 795 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies) {
 796         assert(tr);
 797         assert(j);
 798
 799         if (j->transaction_prev)
 800                 j->transaction_prev->transaction_next = j->transaction_next;
 801         else if (j->transaction_next)
 802                 hashmap_replace(tr->jobs, j->unit, j->transaction_next);
 803         else
 804                 hashmap_remove_value(tr->jobs, j->unit, j);
 805
 806         if (j->transaction_next)
 807                 j->transaction_next->transaction_prev = j->transaction_prev;
 808
 809         j->transaction_prev = j->transaction_next = NULL;
 810
 811         while (j->subject_list)
 812                 job_dependency_free(j->subject_list);
 813
 814         while (j->object_list) {
 815                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 816
 817                 job_dependency_free(j->object_list);
 818
 819                 if (other && delete_dependencies) {
 820                         log_unit_debug(other->unit,
 821                                        "Deleting job %s/%s as dependency of job %s/%s",
 822                                        other->unit->id, job_type_to_string(other->type),
 823                                        j->unit->id, job_type_to_string(j->type));
 824                         transaction_delete_job(tr, other, delete_dependencies);
 825                 }
 826         }
 827 }
 828
 829 int transaction_add_job_and_dependencies(
 830                 Transaction *tr,
 831                 JobType type,
 832                 Unit *unit,
 833                 Job *by,
 834                 bool matters,
 835                 bool override,
 836                 bool conflicts,
 837                 bool ignore_requirements,
 838                 bool ignore_order,
 839                 sd_bus_error *e) {
 840         Job *ret;
 841         Iterator i;
 842         Unit *dep;
 843         int r;
 844         bool is_new;
 845
 846         assert(tr);
 847         assert(type < _JOB_TYPE_MAX);
 848         assert(type < _JOB_TYPE_MAX_IN_TRANSACTION);
 849         assert(unit);
 850
 851         /* Before adding jobs for this unit, let's ensure that its state has been loaded
 852          * This matters when jobs are spawned as part of coldplugging itself (see e. g. path_coldplug()).
 853          * This way, we "recursively" coldplug units, ensuring that we do not look at state of
 854          * not-yet-coldplugged units. */
 855         if (unit->manager->n_reloading > 0)
 856                 unit_coldplug(unit);
 857
 858         /* log_debug("Pulling in %s/%s from %s/%s", */
 859         /*           unit->id, job_type_to_string(type), */
 860         /*           by ? by->unit->id : "NA", */
 861         /*           by ? job_type_to_string(by->type) : "NA"); */
 862
 863         if (!IN_SET(unit->load_state, UNIT_LOADED, UNIT_ERROR, UNIT_NOT_FOUND, UNIT_MASKED))
 864                 return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED,
 865                                          "Unit %s is not loaded properly.", unit->id);
 866
 867         if (type != JOB_STOP && unit->load_state == UNIT_ERROR) {
 868                 if (unit->load_error == -ENOENT || unit->manager->test_run)
 869                         return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED,
 870                                                  "Unit %s failed to load: %s.",
 871                                                  unit->id,
 872                                                  strerror(-unit->load_error));
 873                 else
 874                         return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED,
 875                                                  "Unit %s failed to load: %s. "
 876                                                  "See system logs and 'systemctl status %s' for details.",
 877                                                  unit->id,
 878                                                  strerror(-unit->load_error),
 879                                                  unit->id);
 880         }
 881
 882         if (type != JOB_STOP && unit->load_state == UNIT_NOT_FOUND)
 883                 return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED,
 884                                          "Unit %s failed to load: %s.",
 885                                          unit->id, strerror(-unit->load_error));
 886
 887         if (type != JOB_STOP && unit->load_state == UNIT_MASKED)
 888                 return sd_bus_error_setf(e, BUS_ERROR_UNIT_MASKED,
 889                                          "Unit %s is masked.", unit->id);
 890
 891         if (!unit_job_is_applicable(unit, type))
 892                 return sd_bus_error_setf(e, BUS_ERROR_JOB_TYPE_NOT_APPLICABLE,
 893                                          "Job type %s is not applicable for unit %s.",
 894                                          job_type_to_string(type), unit->id);
 895
 896
 897         /* First add the job. */
 898         ret = transaction_add_one_job(tr, type, unit, override, &is_new);
 899         if (!ret)
 900                 return -ENOMEM;
 901
 902         ret->ignore_order = ret->ignore_order || ignore_order;
 903
 904         /* Then, add a link to the job. */
 905         if (by) {
 906                 if (!job_dependency_new(by, ret, matters, conflicts))
 907                         return -ENOMEM;
 908         } else {
 909                 /* If the job has no parent job, it is the anchor job. */
 910                 assert(!tr->anchor_job);
 911                 tr->anchor_job = ret;
 912         }
 913
 914         if (is_new && !ignore_requirements && type != JOB_NOP) {
 915                 Set *following;
 916
 917                 /* If we are following some other unit, make sure we
 918                  * add all dependencies of everybody following. */
 919                 if (unit_following_set(ret->unit, &following) > 0) {
 920                         SET_FOREACH(dep, following, i) {
 921                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, false, override, false, false, ignore_order, e);
 922                                 if (r < 0) {
 923                                         log_unit_warning(dep, "Cannot add dependency job for, ignoring: %s", bus_error_message(e, r));
 924
 925                                         if (e)
 926                                                 sd_bus_error_free(e);
 927                                 }
 928                         }
 929
 930                         set_free(following);
 931                 }
 932
 933                 /* Finally, recursively add in all dependencies. */
 934                 if (type == JOB_START || type == JOB_RESTART) {
 935                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUIRES], i) {
 936                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, override, false, false, ignore_order, e);
 937                                 if (r < 0) {
 938                                         if (r != -EBADR)
 939                                                 goto fail;
 940
 941                                         if (e)
 942                                                 sd_bus_error_free(e);
 943                                 }
 944                         }
 945
 946                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_BINDS_TO], i) {
 947                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, override, false, false, ignore_order, e);
 948                                 if (r < 0) {
 949                                         if (r != -EBADR)
 950                                                 goto fail;
 951
 952                                         if (e)
 953                                                 sd_bus_error_free(e);
 954                                 }
 955                         }
 956
 957                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUIRES_OVERRIDABLE], i) {
 958                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, !override, override, false, false, ignore_order, e);
 959                                 if (r < 0) {
 960                                         log_unit_full(dep,
 961                                                       r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, r,
 962                                                       "Cannot add dependency job, ignoring: %s",
 963                                                       bus_error_message(e, r));
 964
 965                                         if (e)
 966                                                 sd_bus_error_free(e);
 967                                 }
 968                         }
 969
 970                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_WANTS], i) {
 971                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, false, false, false, false, ignore_order, e);
 972                                 if (r < 0) {
 973                                         log_unit_full(dep,
 974                                                       r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, r,
 975                                                       "Cannot add dependency job, ignoring: %s",
 976                                                       bus_error_message(e, r));
 977
 978                                         if (e)
 979                                                 sd_bus_error_free(e);
 980                                 }
 981                         }
 982
 983                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUISITE], i) {
 984                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, true, override, false, false, ignore_order, e);
 985                                 if (r < 0) {
 986                                         if (r != -EBADR)
 987                                                 goto fail;
 988
 989                                         if (e)
 990                                                 sd_bus_error_free(e);
 991                                 }
 992                         }
 993
 994                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUISITE_OVERRIDABLE], i) {
 995                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, !override, override, false, false, ignore_order, e);
 996                                 if (r < 0) {
 997                                         log_unit_full(dep,
 998                                                       r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, r,
 999                                                       "Cannot add dependency job, ignoring: %s",
1000                                                       bus_error_message(e, r));
1001
1002                                         if (e)
1003                                                 sd_bus_error_free(e);
1004                                 }
1005                         }
1006
1007                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONFLICTS], i) {
1008                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, true, override, true, false, ignore_order, e);
1009                                 if (r < 0) {
1010                                         if (r != -EBADR)
1011                                                 goto fail;
1012
1013                                         if (e)
1014                                                 sd_bus_error_free(e);
1015                                 }
1016                         }
1017
1018                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONFLICTED_BY], i) {
1019                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, false, override, false, false, ignore_order, e);
1020                                 if (r < 0) {
1021                                         log_unit_warning(dep,
1022                                                          "Cannot add dependency job, ignoring: %s",
1023                                                          bus_error_message(e, r));
1024
1025                                         if (e)
1026                                                 sd_bus_error_free(e);
1027                                 }
1028                         }
1029
1030                 }
1031
1032                 if (type == JOB_STOP || type == JOB_RESTART) {
1033                         static const UnitDependency propagate_deps[] = {
1034                                 UNIT_REQUIRED_BY,
1035                                 UNIT_REQUISITE_OF,
1036                                 UNIT_BOUND_BY,
1037                                 UNIT_CONSISTS_OF,
1038                         };
1039
1040                         unsigned j;
1041
1042                         for (j = 0; j < ELEMENTSOF(propagate_deps); j++)
1043                                 SET_FOREACH(dep, ret->unit->dependencies[propagate_deps[j]], i) {
1044
1045                                         r = transaction_add_job_and_dependencies(tr, type, dep, ret, true, override, false, false, ignore_order, e);
1046                                         if (r < 0) {
1047                                                 if (r != -EBADR)
1048                                                         goto fail;
1049
1050                                                 sd_bus_error_free(e);
1051                                         }
1052                                 }
1053                 }
1054
1055                 if (type == JOB_RELOAD) {
1056
1057                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_PROPAGATES_RELOAD_TO], i) {
1058                                 r = transaction_add_job_and_dependencies(tr, JOB_RELOAD, dep, ret, false, override, false, false, ignore_order, e);
1059                                 if (r < 0) {
1060                                         log_unit_warning(dep,
1061                                                          "Cannot add dependency reload job, ignoring: %s",
1062                                                          bus_error_message(e, r));
1063
1064                                         if (e)
1065                                                 sd_bus_error_free(e);
1066                                 }
1067                         }
1068                 }
1069
1070                 /* JOB_VERIFY_STARTED require no dependency handling */
1071         }
1072
1073         return 0;
1074
1075 fail:
1076         return r;
1077 }
1078
1079 int transaction_add_isolate_jobs(Transaction *tr, Manager *m) {
1080         Iterator i;
1081         Unit *u;
1082         char *k;
1083         int r;
1084
1085         assert(tr);
1086         assert(m);
1087
1088         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
1089
1090                 /* ignore aliases */
1091                 if (u->id != k)
1092                         continue;
1093
1094                 if (u->ignore_on_isolate)
1095                         continue;
1096
1097                 /* No need to stop inactive jobs */
1098                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(u)) && !u->job)
1099                         continue;
1100
1101                 /* Is there already something listed for this? */
1102                 if (hashmap_get(tr->jobs, u))
1103                         continue;
1104
1105                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, u, tr->anchor_job, true, false, false, false, false, NULL);
1106                 if (r < 0)
1107                         log_unit_warning_errno(u, r, "Cannot add isolate job, ignoring: %m");
1108         }
1109
1110         return 0;
1111 }
1112
1113 Transaction *transaction_new(bool irreversible) {
1114         Transaction *tr;
1115
1116         tr = new0(Transaction, 1);
1117         if (!tr)
1118                 return NULL;
1119
1120         tr->jobs = hashmap_new(NULL);
1121         if (!tr->jobs) {
1122                 free(tr);
1123                 return NULL;
1124         }
1125
1126         tr->irreversible = irreversible;
1127
1128         return tr;
1129 }
1130
1131 void transaction_free(Transaction *tr) {
1132         assert(hashmap_isempty(tr->jobs));
1133         hashmap_free(tr->jobs);
1134         free(tr);
1135 }