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 "transaction.h"
  26 #include "bus-errors.h"
  27 #include "dbus-common.h"
  28
  29 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies);
  30
  31 static void transaction_delete_job(Transaction *tr, Job *j, bool delete_dependencies) {
  32         assert(tr);
  33         assert(j);
  34
  35         /* Deletes one job from the transaction */
  36
  37         transaction_unlink_job(tr, j, delete_dependencies);
  38
  39         job_free(j);
  40 }
  41
  42 static void transaction_delete_unit(Transaction *tr, Unit *u) {
  43         Job *j;
  44
  45         /* Deletes all jobs associated with a certain unit from the
  46          * transaction */
  47
  48         while ((j = hashmap_get(tr->jobs, u)))
  49                 transaction_delete_job(tr, j, true);
  50 }
  51
  52 void transaction_abort(Transaction *tr) {
  53         Job *j;
  54
  55         assert(tr);
  56
  57         while ((j = hashmap_first(tr->jobs)))
  58                 transaction_delete_job(tr, j, false);
  59
  60         assert(hashmap_isempty(tr->jobs));
  61 }
  62
  63 static void transaction_find_jobs_that_matter_to_anchor(Job *j, unsigned generation) {
  64         JobDependency *l;
  65
  66         /* A recursive sweep through the graph that marks all units
  67          * that matter to the anchor job, i.e. are directly or
  68          * indirectly a dependency of the anchor job via paths that
  69          * are fully marked as mattering. */
  70
  71         j->matters_to_anchor = true;
  72         j->generation = generation;
  73
  74         LIST_FOREACH(subject, l, j->subject_list) {
  75
  76                 /* This link does not matter */
  77                 if (!l->matters)
  78                         continue;
  79
  80                 /* This unit has already been marked */
  81                 if (l->object->generation == generation)
  82                         continue;
  83
  84                 transaction_find_jobs_that_matter_to_anchor(l->object, generation);
  85         }
  86 }
  87
  88 static void transaction_merge_and_delete_job(Transaction *tr, Job *j, Job *other, JobType t) {
  89         JobDependency *l, *last;
  90
  91         assert(j);
  92         assert(other);
  93         assert(j->unit == other->unit);
  94         assert(!j->installed);
  95
  96         /* Merges 'other' into 'j' and then deletes 'other'. */
  97
  98         j->type = t;
  99         j->state = JOB_WAITING;
 100         j->override = j->override || other->override;
 101         j->irreversible = j->irreversible || other->irreversible;
 102
 103         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
 104
 105         /* Patch us in as new owner of the JobDependency objects */
 106         last = NULL;
 107         LIST_FOREACH(subject, l, other->subject_list) {
 108                 assert(l->subject == other);
 109                 l->subject = j;
 110                 last = l;
 111         }
 112
 113         /* Merge both lists */
 114         if (last) {
 115                 last->subject_next = j->subject_list;
 116                 if (j->subject_list)
 117                         j->subject_list->subject_prev = last;
 118                 j->subject_list = other->subject_list;
 119         }
 120
 121         /* Patch us in as new owner of the JobDependency objects */
 122         last = NULL;
 123         LIST_FOREACH(object, l, other->object_list) {
 124                 assert(l->object == other);
 125                 l->object = j;
 126                 last = l;
 127         }
 128
 129         /* Merge both lists */
 130         if (last) {
 131                 last->object_next = j->object_list;
 132                 if (j->object_list)
 133                         j->object_list->object_prev = last;
 134                 j->object_list = other->object_list;
 135         }
 136
 137         /* Kill the other job */
 138         other->subject_list = NULL;
 139         other->object_list = NULL;
 140         transaction_delete_job(tr, other, true);
 141 }
 142
 143 _pure_ static bool job_is_conflicted_by(Job *j) {
 144         JobDependency *l;
 145
 146         assert(j);
 147
 148         /* Returns true if this job is pulled in by a least one
 149          * ConflictedBy dependency. */
 150
 151         LIST_FOREACH(object, l, j->object_list)
 152                 if (l->conflicts)
 153                         return true;
 154
 155         return false;
 156 }
 157
 158 static int delete_one_unmergeable_job(Transaction *tr, Job *j) {
 159         Job *k;
 160
 161         assert(j);
 162
 163         /* Tries to delete one item in the linked list
 164          * j->transaction_next->transaction_next->... that conflicts
 165          * with another one, in an attempt to make an inconsistent
 166          * transaction work. */
 167
 168         /* We rely here on the fact that if a merged with b does not
 169          * merge with c, either a or b merge with c neither */
 170         LIST_FOREACH(transaction, j, j)
 171                 LIST_FOREACH(transaction, k, j->transaction_next) {
 172                         Job *d;
 173
 174                         /* Is this one mergeable? Then skip it */
 175                         if (job_type_is_mergeable(j->type, k->type))
 176                                 continue;
 177
 178                         /* Ok, we found two that conflict, let's see if we can
 179                          * drop one of them */
 180                         if (!j->matters_to_anchor && !k->matters_to_anchor) {
 181
 182                                 /* Both jobs don't matter, so let's
 183                                  * find the one that is smarter to
 184                                  * remove. Let's think positive and
 185                                  * rather remove stops then starts --
 186                                  * except if something is being
 187                                  * stopped because it is conflicted by
 188                                  * another unit in which case we
 189                                  * rather remove the start. */
 190
 191                                 log_debug_unit(j->unit->id,
 192                                                "Looking at job %s/%s conflicted_by=%s",
 193                                                j->unit->id, job_type_to_string(j->type),
 194                                                yes_no(j->type == JOB_STOP && job_is_conflicted_by(j)));
 195                                 log_debug_unit(k->unit->id,
 196                                                "Looking at job %s/%s conflicted_by=%s",
 197                                                k->unit->id, job_type_to_string(k->type),
 198                                                yes_no(k->type == JOB_STOP && job_is_conflicted_by(k)));
 199
 200                                 if (j->type == JOB_STOP) {
 201
 202                                         if (job_is_conflicted_by(j))
 203                                                 d = k;
 204                                         else
 205                                                 d = j;
 206
 207                                 } else if (k->type == JOB_STOP) {
 208
 209                                         if (job_is_conflicted_by(k))
 210                                                 d = j;
 211                                         else
 212                                                 d = k;
 213                                 } else
 214                                         d = j;
 215
 216                         } else if (!j->matters_to_anchor)
 217                                 d = j;
 218                         else if (!k->matters_to_anchor)
 219                                 d = k;
 220                         else
 221                                 return -ENOEXEC;
 222
 223                         /* Ok, we can drop one, so let's do so. */
 224                         log_debug_unit(d->unit->id,
 225                                        "Fixing conflicting jobs by deleting job %s/%s",
 226                                        d->unit->id, job_type_to_string(d->type));
 227                         transaction_delete_job(tr, d, true);
 228                         return 0;
 229                 }
 230
 231         return -EINVAL;
 232 }
 233
 234 static int transaction_merge_jobs(Transaction *tr, DBusError *e) {
 235         Job *j;
 236         Iterator i;
 237         int r;
 238
 239         assert(tr);
 240
 241         /* First step, check whether any of the jobs for one specific
 242          * task conflict. If so, try to drop one of them. */
 243         HASHMAP_FOREACH(j, tr->jobs, i) {
 244                 JobType t;
 245                 Job *k;
 246
 247                 t = j->type;
 248                 LIST_FOREACH(transaction, k, j->transaction_next) {
 249                         if (job_type_merge_and_collapse(&t, k->type, j->unit) >= 0)
 250                                 continue;
 251
 252                         /* OK, we could not merge all jobs for this
 253                          * action. Let's see if we can get rid of one
 254                          * of them */
 255
 256                         r = delete_one_unmergeable_job(tr, j);
 257                         if (r >= 0)
 258                                 /* Ok, we managed to drop one, now
 259                                  * let's ask our callers to call us
 260                                  * again after garbage collecting */
 261                                 return -EAGAIN;
 262
 263                         /* We couldn't merge anything. Failure */
 264                         dbus_set_error(e, BUS_ERROR_TRANSACTION_JOBS_CONFLICTING, "Transaction contains conflicting jobs '%s' and '%s' for %s. Probably contradicting requirement dependencies configured.",
 265                                        job_type_to_string(t), job_type_to_string(k->type), k->unit->id);
 266                         return r;
 267                 }
 268         }
 269
 270         /* Second step, merge the jobs. */
 271         HASHMAP_FOREACH(j, tr->jobs, i) {
 272                 JobType t = j->type;
 273                 Job *k;
 274
 275                 /* Merge all transaction jobs for j->unit */
 276                 LIST_FOREACH(transaction, k, j->transaction_next)
 277                         assert_se(job_type_merge_and_collapse(&t, k->type, j->unit) == 0);
 278
 279                 while ((k = j->transaction_next)) {
 280                         if (tr->anchor_job == k) {
 281                                 transaction_merge_and_delete_job(tr, k, j, t);
 282                                 j = k;
 283                         } else
 284                                 transaction_merge_and_delete_job(tr, j, k, t);
 285                 }
 286
 287                 assert(!j->transaction_next);
 288                 assert(!j->transaction_prev);
 289         }
 290
 291         return 0;
 292 }
 293
 294 static void transaction_drop_redundant(Transaction *tr) {
 295         Job *j;
 296         Iterator i;
 297
 298         /* Goes through the transaction and removes all jobs of the units
 299          * whose jobs are all noops. If not all of a unit's jobs are
 300          * redundant, they are kept. */
 301
 302         assert(tr);
 303
 304 rescan:
 305         HASHMAP_FOREACH(j, tr->jobs, i) {
 306                 Job *k;
 307
 308                 LIST_FOREACH(transaction, k, j) {
 309
 310                         if (tr->anchor_job == k ||
 311                             !job_type_is_redundant(k->type, unit_active_state(k->unit)) ||
 312                             (k->unit->job && job_type_is_conflicting(k->type, k->unit->job->type)))
 313                                 goto next_unit;
 314                 }
 315
 316                 /* log_debug("Found redundant job %s/%s, dropping.", j->unit->id, job_type_to_string(j->type)); */
 317                 transaction_delete_job(tr, j, false);
 318                 goto rescan;
 319         next_unit:;
 320         }
 321 }
 322
 323 _pure_ static bool unit_matters_to_anchor(Unit *u, Job *j) {
 324         assert(u);
 325         assert(!j->transaction_prev);
 326
 327         /* Checks whether at least one of the jobs for this unit
 328          * matters to the anchor. */
 329
 330         LIST_FOREACH(transaction, j, j)
 331                 if (j->matters_to_anchor)
 332                         return true;
 333
 334         return false;
 335 }
 336
 337 static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsigned generation, DBusError *e) {
 338         Iterator i;
 339         Unit *u;
 340         int r;
 341
 342         assert(tr);
 343         assert(j);
 344         assert(!j->transaction_prev);
 345
 346         /* Does a recursive sweep through the ordering graph, looking
 347          * for a cycle. If we find cycle we try to break it. */
 348
 349         /* Have we seen this before? */
 350         if (j->generation == generation) {
 351                 Job *k, *delete;
 352
 353                 /* If the marker is NULL we have been here already and
 354                  * decided the job was loop-free from here. Hence
 355                  * shortcut things and return right-away. */
 356                 if (!j->marker)
 357                         return 0;
 358
 359                 /* So, the marker is not NULL and we already have been
 360                  * here. We have a cycle. Let's try to break it. We go
 361                  * backwards in our path and try to find a suitable
 362                  * job to remove. We use the marker to find our way
 363                  * back, since smart how we are we stored our way back
 364                  * in there. */
 365                 log_warning_unit(j->unit->id,
 366                                  "Found ordering cycle on %s/%s",
 367                                  j->unit->id, job_type_to_string(j->type));
 368
 369                 delete = NULL;
 370                 for (k = from; k; k = ((k->generation == generation && k->marker != k) ? k->marker : NULL)) {
 371
 372                         /* logging for j not k here here to provide consistent narrative */
 373                         log_info_unit(j->unit->id,
 374                                       "Walked on cycle path to %s/%s",
 375                                       k->unit->id, job_type_to_string(k->type));
 376
 377                         if (!delete &&
 378                             !unit_matters_to_anchor(k->unit, k)) {
 379                                 /* Ok, we can drop this one, so let's
 380                                  * do so. */
 381                                 delete = k;
 382                         }
 383
 384                         /* Check if this in fact was the beginning of
 385                          * the cycle */
 386                         if (k == j)
 387                                 break;
 388                 }
 389
 390
 391                 if (delete) {
 392                         /* logging for j not k here here to provide consistent narrative */
 393                         log_warning_unit(j->unit->id,
 394                                          "Breaking ordering cycle by deleting job %s/%s",
 395                                          delete->unit->id, job_type_to_string(delete->type));
 396                         log_error_unit(delete->unit->id,
 397                                        "Job %s/%s deleted to break ordering cycle starting with %s/%s",
 398                                        delete->unit->id, job_type_to_string(delete->type),
 399                                        j->unit->id, job_type_to_string(j->type));
 400                         unit_status_printf(delete->unit, ANSI_HIGHLIGHT_RED_ON " SKIP " ANSI_HIGHLIGHT_OFF,
 401                                            "Ordering cycle found, skipping %s");
 402                         transaction_delete_unit(tr, delete->unit);
 403                         return -EAGAIN;
 404                 }
 405
 406                 log_error("Unable to break cycle");
 407
 408                 dbus_set_error(e, BUS_ERROR_TRANSACTION_ORDER_IS_CYCLIC,
 409                                "Transaction order is cyclic. See system logs for details.");
 410                 return -ENOEXEC;
 411         }
 412
 413         /* Make the marker point to where we come from, so that we can
 414          * find our way backwards if we want to break a cycle. We use
 415          * a special marker for the beginning: we point to
 416          * ourselves. */
 417         j->marker = from ? from : j;
 418         j->generation = generation;
 419
 420         /* We assume that the dependencies are bidirectional, and
 421          * hence can ignore UNIT_AFTER */
 422         SET_FOREACH(u, j->unit->dependencies[UNIT_BEFORE], i) {
 423                 Job *o;
 424
 425                 /* Is there a job for this unit? */
 426                 o = hashmap_get(tr->jobs, u);
 427                 if (!o) {
 428                         /* Ok, there is no job for this in the
 429                          * transaction, but maybe there is already one
 430                          * running? */
 431                         o = u->job;
 432                         if (!o)
 433                                 continue;
 434                 }
 435
 436                 r = transaction_verify_order_one(tr, o, j, generation, e);
 437                 if (r < 0)
 438                         return r;
 439         }
 440
 441         /* Ok, let's backtrack, and remember that this entry is not on
 442          * our path anymore. */
 443         j->marker = NULL;
 444
 445         return 0;
 446 }
 447
 448 static int transaction_verify_order(Transaction *tr, unsigned *generation, DBusError *e) {
 449         Job *j;
 450         int r;
 451         Iterator i;
 452         unsigned g;
 453
 454         assert(tr);
 455         assert(generation);
 456
 457         /* Check if the ordering graph is cyclic. If it is, try to fix
 458          * that up by dropping one of the jobs. */
 459
 460         g = (*generation)++;
 461
 462         HASHMAP_FOREACH(j, tr->jobs, i)
 463                 if ((r = transaction_verify_order_one(tr, j, NULL, g, e)) < 0)
 464                         return r;
 465
 466         return 0;
 467 }
 468
 469 static void transaction_collect_garbage(Transaction *tr) {
 470         Iterator i;
 471         Job *j;
 472
 473         assert(tr);
 474
 475         /* Drop jobs that are not required by any other job */
 476
 477 rescan:
 478         HASHMAP_FOREACH(j, tr->jobs, i) {
 479                 if (tr->anchor_job == j || j->object_list) {
 480                         /* log_debug("Keeping job %s/%s because of %s/%s", */
 481                         /*           j->unit->id, job_type_to_string(j->type), */
 482                         /*           j->object_list->subject ? j->object_list->subject->unit->id : "root", */
 483                         /*           j->object_list->subject ? job_type_to_string(j->object_list->subject->type) : "root"); */
 484                         continue;
 485                 }
 486
 487                 /* log_debug("Garbage collecting job %s/%s", j->unit->id, job_type_to_string(j->type)); */
 488                 transaction_delete_job(tr, j, true);
 489                 goto rescan;
 490         }
 491 }
 492
 493 static int transaction_is_destructive(Transaction *tr, JobMode mode, DBusError *e) {
 494         Iterator i;
 495         Job *j;
 496
 497         assert(tr);
 498
 499         /* Checks whether applying this transaction means that
 500          * existing jobs would be replaced */
 501
 502         HASHMAP_FOREACH(j, tr->jobs, i) {
 503
 504                 /* Assume merged */
 505                 assert(!j->transaction_prev);
 506                 assert(!j->transaction_next);
 507
 508                 if (j->unit->job && (mode == JOB_FAIL || j->unit->job->irreversible) &&
 509                     !job_type_is_superset(j->type, j->unit->job->type)) {
 510
 511                         dbus_set_error(e, BUS_ERROR_TRANSACTION_IS_DESTRUCTIVE, "Transaction is destructive.");
 512                         return -EEXIST;
 513                 }
 514         }
 515
 516         return 0;
 517 }
 518
 519 static void transaction_minimize_impact(Transaction *tr) {
 520         Job *j;
 521         Iterator i;
 522
 523         assert(tr);
 524
 525         /* Drops all unnecessary jobs that reverse already active jobs
 526          * or that stop a running service. */
 527
 528 rescan:
 529         HASHMAP_FOREACH(j, tr->jobs, i) {
 530                 LIST_FOREACH(transaction, j, j) {
 531                         bool stops_running_service, changes_existing_job;
 532
 533                         /* If it matters, we shouldn't drop it */
 534                         if (j->matters_to_anchor)
 535                                 continue;
 536
 537                         /* Would this stop a running service?
 538                          * Would this change an existing job?
 539                          * If so, let's drop this entry */
 540
 541                         stops_running_service =
 542                                 j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 543
 544                         changes_existing_job =
 545                                 j->unit->job &&
 546                                 job_type_is_conflicting(j->type, j->unit->job->type);
 547
 548                         if (!stops_running_service && !changes_existing_job)
 549                                 continue;
 550
 551                         if (stops_running_service)
 552                                 log_debug_unit(j->unit->id,
 553                                                "%s/%s would stop a running service.",
 554                                                j->unit->id, job_type_to_string(j->type));
 555
 556                         if (changes_existing_job)
 557                                 log_debug_unit(j->unit->id,
 558                                                "%s/%s would change existing job.",
 559                                                j->unit->id, job_type_to_string(j->type));
 560
 561                         /* Ok, let's get rid of this */
 562                         log_debug_unit(j->unit->id,
 563                                        "Deleting %s/%s to minimize impact.",
 564                                        j->unit->id, job_type_to_string(j->type));
 565
 566                         transaction_delete_job(tr, j, true);
 567                         goto rescan;
 568                 }
 569         }
 570 }
 571
 572 static int transaction_apply(Transaction *tr, Manager *m, JobMode mode) {
 573         Iterator i;
 574         Job *j;
 575         int r;
 576
 577         /* Moves the transaction jobs to the set of active jobs */
 578
 579         if (mode == JOB_ISOLATE) {
 580
 581                 /* When isolating first kill all installed jobs which
 582                  * aren't part of the new transaction */
 583                 HASHMAP_FOREACH(j, m->jobs, i) {
 584                         assert(j->installed);
 585
 586                         if (hashmap_get(tr->jobs, j->unit))
 587                                 continue;
 588
 589                         /* Not invalidating recursively. Avoids triggering
 590                          * OnFailure= actions of dependent jobs. Also avoids
 591                          * invalidating our iterator. */
 592                         job_finish_and_invalidate(j, JOB_CANCELED, false);
 593                 }
 594         }
 595
 596         HASHMAP_FOREACH(j, tr->jobs, i) {
 597                 /* Assume merged */
 598                 assert(!j->transaction_prev);
 599                 assert(!j->transaction_next);
 600
 601                 r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j);
 602                 if (r < 0)
 603                         goto rollback;
 604         }
 605
 606         while ((j = hashmap_steal_first(tr->jobs))) {
 607                 Job *installed_job;
 608
 609                 /* Clean the job dependencies */
 610                 transaction_unlink_job(tr, j, false);
 611
 612                 installed_job = job_install(j);
 613                 if (installed_job != j) {
 614                         /* j has been merged into a previously installed job */
 615                         if (tr->anchor_job == j)
 616                                 tr->anchor_job = installed_job;
 617                         hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 618                         job_free(j);
 619                         j = installed_job;
 620                 }
 621
 622                 job_add_to_run_queue(j);
 623                 job_add_to_dbus_queue(j);
 624                 job_start_timer(j);
 625                 job_shutdown_magic(j);
 626         }
 627
 628         return 0;
 629
 630 rollback:
 631
 632         HASHMAP_FOREACH(j, tr->jobs, i)
 633                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 634
 635         return r;
 636 }
 637
 638 int transaction_activate(Transaction *tr, Manager *m, JobMode mode, DBusError *e) {
 639         Iterator i;
 640         Job *j;
 641         int r;
 642         unsigned generation = 1;
 643
 644         assert(tr);
 645
 646         /* This applies the changes recorded in tr->jobs to
 647          * the actual list of jobs, if possible. */
 648
 649         /* Reset the generation counter of all installed jobs. The detection of cycles
 650          * looks at installed jobs. If they had a non-zero generation from some previous
 651          * walk of the graph, the algorithm would break. */
 652         HASHMAP_FOREACH(j, m->jobs, i)
 653                 j->generation = 0;
 654
 655         /* First step: figure out which jobs matter */
 656         transaction_find_jobs_that_matter_to_anchor(tr->anchor_job, generation++);
 657
 658         /* Second step: Try not to stop any running services if
 659          * we don't have to. Don't try to reverse running
 660          * jobs if we don't have to. */
 661         if (mode == JOB_FAIL)
 662                 transaction_minimize_impact(tr);
 663
 664         /* Third step: Drop redundant jobs */
 665         transaction_drop_redundant(tr);
 666
 667         for (;;) {
 668                 /* Fourth step: Let's remove unneeded jobs that might
 669                  * be lurking. */
 670                 if (mode != JOB_ISOLATE)
 671                         transaction_collect_garbage(tr);
 672
 673                 /* Fifth step: verify order makes sense and correct
 674                  * cycles if necessary and possible */
 675                 r = transaction_verify_order(tr, &generation, e);
 676                 if (r >= 0)
 677                         break;
 678
 679                 if (r != -EAGAIN) {
 680                         log_warning("Requested transaction contains an unfixable cyclic ordering dependency: %s", bus_error(e, r));
 681                         return r;
 682                 }
 683
 684                 /* Let's see if the resulting transaction ordering
 685                  * graph is still cyclic... */
 686         }
 687
 688         for (;;) {
 689                 /* Sixth step: let's drop unmergeable entries if
 690                  * necessary and possible, merge entries we can
 691                  * merge */
 692                 r = transaction_merge_jobs(tr, e);
 693                 if (r >= 0)
 694                         break;
 695
 696                 if (r != -EAGAIN) {
 697                         log_warning("Requested transaction contains unmergeable jobs: %s", bus_error(e, r));
 698                         return r;
 699                 }
 700
 701                 /* Seventh step: an entry got dropped, let's garbage
 702                  * collect its dependencies. */
 703                 if (mode != JOB_ISOLATE)
 704                         transaction_collect_garbage(tr);
 705
 706                 /* Let's see if the resulting transaction still has
 707                  * unmergeable entries ... */
 708         }
 709
 710         /* Eights step: Drop redundant jobs again, if the merging now allows us to drop more. */
 711         transaction_drop_redundant(tr);
 712
 713         /* Ninth step: check whether we can actually apply this */
 714         r = transaction_is_destructive(tr, mode, e);
 715         if (r < 0) {
 716                 log_notice("Requested transaction contradicts existing jobs: %s", bus_error(e, r));
 717                 return r;
 718         }
 719
 720         /* Tenth step: apply changes */
 721         r = transaction_apply(tr, m, mode);
 722         if (r < 0) {
 723                 log_warning("Failed to apply transaction: %s", strerror(-r));
 724                 return r;
 725         }
 726
 727         assert(hashmap_isempty(tr->jobs));
 728
 729         if (!hashmap_isempty(m->jobs)) {
 730                 /* Are there any jobs now? Then make sure we have the
 731                  * idle pipe around. We don't really care too much
 732                  * whether this works or not, as the idle pipe is a
 733                  * feature for cosmetics, not actually useful for
 734                  * anything beyond that. */
 735
 736                 if (m->idle_pipe[0] < 0 && m->idle_pipe[1] < 0)
 737                         pipe2(m->idle_pipe, O_NONBLOCK|O_CLOEXEC);
 738         }
 739
 740         return 0;
 741 }
 742
 743 static Job* transaction_add_one_job(Transaction *tr, JobType type, Unit *unit, bool override, bool *is_new) {
 744         Job *j, *f;
 745
 746         assert(tr);
 747         assert(unit);
 748
 749         /* Looks for an existing prospective job and returns that. If
 750          * it doesn't exist it is created and added to the prospective
 751          * jobs list. */
 752
 753         f = hashmap_get(tr->jobs, unit);
 754
 755         LIST_FOREACH(transaction, j, f) {
 756                 assert(j->unit == unit);
 757
 758                 if (j->type == type) {
 759                         if (is_new)
 760                                 *is_new = false;
 761                         return j;
 762                 }
 763         }
 764
 765         j = job_new(unit, type);
 766         if (!j)
 767                 return NULL;
 768
 769         j->generation = 0;
 770         j->marker = NULL;
 771         j->matters_to_anchor = false;
 772         j->override = override;
 773         j->irreversible = tr->irreversible;
 774
 775         LIST_PREPEND(Job, transaction, f, j);
 776
 777         if (hashmap_replace(tr->jobs, unit, f) < 0) {
 778                 LIST_REMOVE(Job, transaction, f, j);
 779                 job_free(j);
 780                 return NULL;
 781         }
 782
 783         if (is_new)
 784                 *is_new = true;
 785
 786         /* log_debug("Added job %s/%s to transaction.", unit->id, job_type_to_string(type)); */
 787
 788         return j;
 789 }
 790
 791 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies) {
 792         assert(tr);
 793         assert(j);
 794
 795         if (j->transaction_prev)
 796                 j->transaction_prev->transaction_next = j->transaction_next;
 797         else if (j->transaction_next)
 798                 hashmap_replace(tr->jobs, j->unit, j->transaction_next);
 799         else
 800                 hashmap_remove_value(tr->jobs, j->unit, j);
 801
 802         if (j->transaction_next)
 803                 j->transaction_next->transaction_prev = j->transaction_prev;
 804
 805         j->transaction_prev = j->transaction_next = NULL;
 806
 807         while (j->subject_list)
 808                 job_dependency_free(j->subject_list);
 809
 810         while (j->object_list) {
 811                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 812
 813                 job_dependency_free(j->object_list);
 814
 815                 if (other && delete_dependencies) {
 816                         log_debug_unit(other->unit->id,
 817                                        "Deleting job %s/%s as dependency of job %s/%s",
 818                                        other->unit->id, job_type_to_string(other->type),
 819                                        j->unit->id, job_type_to_string(j->type));
 820                         transaction_delete_job(tr, other, delete_dependencies);
 821                 }
 822         }
 823 }
 824
 825 int transaction_add_job_and_dependencies(
 826                 Transaction *tr,
 827                 JobType type,
 828                 Unit *unit,
 829                 Job *by,
 830                 bool matters,
 831                 bool override,
 832                 bool conflicts,
 833                 bool ignore_requirements,
 834                 bool ignore_order,
 835                 DBusError *e) {
 836         Job *ret;
 837         Iterator i;
 838         Unit *dep;
 839         int r;
 840         bool is_new;
 841
 842         assert(tr);
 843         assert(type < _JOB_TYPE_MAX);
 844         assert(type < _JOB_TYPE_MAX_IN_TRANSACTION);
 845         assert(unit);
 846
 847         /* log_debug("Pulling in %s/%s from %s/%s", */
 848         /*           unit->id, job_type_to_string(type), */
 849         /*           by ? by->unit->id : "NA", */
 850         /*           by ? job_type_to_string(by->type) : "NA"); */
 851
 852         if (unit->load_state != UNIT_LOADED &&
 853             unit->load_state != UNIT_ERROR &&
 854             unit->load_state != UNIT_NOT_FOUND &&
 855             unit->load_state != UNIT_MASKED) {
 856                 dbus_set_error(e, BUS_ERROR_LOAD_FAILED, "Unit %s is not loaded properly.", unit->id);
 857                 return -EINVAL;
 858         }
 859
 860         if (type != JOB_STOP && (unit->load_state == UNIT_ERROR || unit->load_state == UNIT_NOT_FOUND)) {
 861                 dbus_set_error(e, BUS_ERROR_LOAD_FAILED,
 862                                "Unit %s failed to load: %s. "
 863                                "See system logs and 'systemctl status %s' for details.",
 864                                unit->id,
 865                                strerror(-unit->load_error),
 866                                unit->id);
 867                 return -EINVAL;
 868         }
 869
 870         if (type != JOB_STOP && unit->load_state == UNIT_MASKED) {
 871                 dbus_set_error(e, BUS_ERROR_MASKED, "Unit %s is masked.", unit->id);
 872                 return -EADDRNOTAVAIL;
 873         }
 874
 875         if (!unit_job_is_applicable(unit, type)) {
 876                 dbus_set_error(e, BUS_ERROR_JOB_TYPE_NOT_APPLICABLE, "Job type %s is not applicable for unit %s.", job_type_to_string(type), unit->id);
 877                 return -EBADR;
 878         }
 879
 880         /* First add the job. */
 881         ret = transaction_add_one_job(tr, type, unit, override, &is_new);
 882         if (!ret)
 883                 return -ENOMEM;
 884
 885         ret->ignore_order = ret->ignore_order || ignore_order;
 886
 887         /* Then, add a link to the job. */
 888         if (by) {
 889                 if (!job_dependency_new(by, ret, matters, conflicts))
 890                         return -ENOMEM;
 891         } else {
 892                 /* If the job has no parent job, it is the anchor job. */
 893                 assert(!tr->anchor_job);
 894                 tr->anchor_job = ret;
 895         }
 896
 897         if (is_new && !ignore_requirements && type != JOB_NOP) {
 898                 Set *following;
 899
 900                 /* If we are following some other unit, make sure we
 901                  * add all dependencies of everybody following. */
 902                 if (unit_following_set(ret->unit, &following) > 0) {
 903                         SET_FOREACH(dep, following, i) {
 904                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, false, override, false, false, ignore_order, e);
 905                                 if (r < 0) {
 906                                         log_warning_unit(dep->id,
 907                                                          "Cannot add dependency job for unit %s, ignoring: %s",
 908                                                          dep->id, bus_error(e, r));
 909
 910                                         if (e)
 911                                                 dbus_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, override, false, false, ignore_order, e);
 922                                 if (r < 0) {
 923                                         if (r != -EBADR)
 924                                                 goto fail;
 925
 926                                         if (e)
 927                                                 dbus_error_free(e);
 928                                 }
 929                         }
 930
 931                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_BINDS_TO], i) {
 932                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, override, false, false, ignore_order, e);
 933                                 if (r < 0) {
 934                                         if (r != -EBADR)
 935                                                 goto fail;
 936
 937                                         if (e)
 938                                                 dbus_error_free(e);
 939                                 }
 940                         }
 941
 942                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUIRES_OVERRIDABLE], i) {
 943                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, !override, override, false, false, ignore_order, e);
 944                                 if (r < 0) {
 945                                         log_full_unit(r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, dep->id,
 946                                                       "Cannot add dependency job for unit %s, ignoring: %s",
 947                                                       dep->id, bus_error(e, r));
 948
 949                                         if (e)
 950                                                 dbus_error_free(e);
 951                                 }
 952                         }
 953
 954                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_WANTS], i) {
 955                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, false, false, false, false, ignore_order, e);
 956                                 if (r < 0) {
 957                                         log_full_unit(r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, dep->id,
 958                                                       "Cannot add dependency job for unit %s, ignoring: %s",
 959                                                       dep->id, bus_error(e, r));
 960
 961                                         if (e)
 962                                                 dbus_error_free(e);
 963                                 }
 964                         }
 965
 966                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUISITE], i) {
 967                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, true, override, false, false, ignore_order, e);
 968                                 if (r < 0) {
 969                                         if (r != -EBADR)
 970                                                 goto fail;
 971
 972                                         if (e)
 973                                                 dbus_error_free(e);
 974                                 }
 975                         }
 976
 977                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUISITE_OVERRIDABLE], i) {
 978                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, !override, override, false, false, ignore_order, e);
 979                                 if (r < 0) {
 980                                         log_full_unit(r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, dep->id,
 981                                                       "Cannot add dependency job for unit %s, ignoring: %s",
 982                                                       dep->id, bus_error(e, r));
 983
 984                                         if (e)
 985                                                 dbus_error_free(e);
 986                                 }
 987                         }
 988
 989                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONFLICTS], i) {
 990                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, true, override, true, false, ignore_order, e);
 991                                 if (r < 0) {
 992                                         if (r != -EBADR)
 993                                                 goto fail;
 994
 995                                         if (e)
 996                                                 dbus_error_free(e);
 997                                 }
 998                         }
 999
1000                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONFLICTED_BY], i) {
1001                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, false, override, false, false, ignore_order, e);
1002                                 if (r < 0) {
1003                                         log_warning_unit(dep->id,
1004                                                          "Cannot add dependency job for unit %s, ignoring: %s",
1005                                                          dep->id, bus_error(e, r));
1006
1007                                         if (e)
1008                                                 dbus_error_free(e);
1009                                 }
1010                         }
1011
1012                 }
1013
1014                 if (type == JOB_STOP || type == JOB_RESTART) {
1015
1016                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUIRED_BY], i) {
1017                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, true, override, false, false, ignore_order, e);
1018                                 if (r < 0) {
1019                                         if (r != -EBADR)
1020                                                 goto fail;
1021
1022                                         if (e)
1023                                                 dbus_error_free(e);
1024                                 }
1025                         }
1026
1027                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_BOUND_BY], i) {
1028                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, true, override, false, false, ignore_order, e);
1029                                 if (r < 0) {
1030                                         if (r != -EBADR)
1031                                                 goto fail;
1032
1033                                         if (e)
1034                                                 dbus_error_free(e);
1035                                 }
1036                         }
1037
1038                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONSISTS_OF], i) {
1039                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, true, override, false, false, ignore_order, e);
1040                                 if (r < 0) {
1041                                         if (r != -EBADR)
1042                                                 goto fail;
1043
1044                                         if (e)
1045                                                 dbus_error_free(e);
1046                                 }
1047                         }
1048
1049                 }
1050
1051                 if (type == JOB_RELOAD) {
1052
1053                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_PROPAGATES_RELOAD_TO], i) {
1054                                 r = transaction_add_job_and_dependencies(tr, JOB_RELOAD, dep, ret, false, override, false, false, ignore_order, e);
1055                                 if (r < 0) {
1056                                         log_warning_unit(dep->id,
1057                                                          "Cannot add dependency reload job for unit %s, ignoring: %s",
1058                                                          dep->id, bus_error(e, r));
1059
1060                                         if (e)
1061                                                 dbus_error_free(e);
1062                                 }
1063                         }
1064                 }
1065
1066                 /* JOB_VERIFY_STARTED require no dependency handling */
1067         }
1068
1069         return 0;
1070
1071 fail:
1072         return r;
1073 }
1074
1075 int transaction_add_isolate_jobs(Transaction *tr, Manager *m) {
1076         Iterator i;
1077         Unit *u;
1078         char *k;
1079         int r;
1080
1081         assert(tr);
1082         assert(m);
1083
1084         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
1085
1086                 /* ignore aliases */
1087                 if (u->id != k)
1088                         continue;
1089
1090                 if (u->ignore_on_isolate)
1091                         continue;
1092
1093                 /* No need to stop inactive jobs */
1094                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(u)) && !u->job)
1095                         continue;
1096
1097                 /* Is there already something listed for this? */
1098                 if (hashmap_get(tr->jobs, u))
1099                         continue;
1100
1101                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, u, tr->anchor_job, true, false, false, false, false, NULL);
1102                 if (r < 0)
1103                         log_warning_unit(u->id,
1104                                          "Cannot add isolate job for unit %s, ignoring: %s",
1105                                          u->id, strerror(-r));
1106         }
1107
1108         return 0;
1109 }
1110
1111 Transaction *transaction_new(bool irreversible) {
1112         Transaction *tr;
1113
1114         tr = new0(Transaction, 1);
1115         if (!tr)
1116                 return NULL;
1117
1118         tr->jobs = hashmap_new(trivial_hash_func, trivial_compare_func);
1119         if (!tr->jobs) {
1120                 free(tr);
1121                 return NULL;
1122         }
1123
1124         tr->irreversible = irreversible;
1125
1126         return tr;
1127 }
1128
1129 void transaction_free(Transaction *tr) {
1130         assert(hashmap_isempty(tr->jobs));
1131         hashmap_free(tr->jobs);
1132         free(tr);
1133 }