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) && !unit_matters_to_anchor(k->unit, k))
 384                                 /* Ok, we can drop this one, so let's
 385                                  * do so. */
 386                                 delete = k;
 387
 388                         /* Check if this in fact was the beginning of
 389                          * the cycle */
 390                         if (k == j)
 391                                 break;
 392                 }
 393
 394
 395                 if (delete) {
 396                         /* logging for j not k here here to provide consistent narrative */
 397                         log_unit_warning(j->unit,
 398                                          "Breaking ordering cycle by deleting job %s/%s",
 399                                          delete->unit->id, job_type_to_string(delete->type));
 400                         log_unit_error(delete->unit,
 401                                        "Job %s/%s deleted to break ordering cycle starting with %s/%s",
 402                                        delete->unit->id, job_type_to_string(delete->type),
 403                                        j->unit->id, job_type_to_string(j->type));
 404                         unit_status_printf(delete->unit, ANSI_HIGHLIGHT_RED_ON " SKIP " ANSI_HIGHLIGHT_OFF,
 405                                            "Ordering cycle found, skipping %s");
 406                         transaction_delete_unit(tr, delete->unit);
 407                         return -EAGAIN;
 408                 }
 409
 410                 log_error("Unable to break cycle");
 411
 412                 return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_ORDER_IS_CYCLIC,
 413                                          "Transaction order is cyclic. See system logs for details.");
 414         }
 415
 416         /* Make the marker point to where we come from, so that we can
 417          * find our way backwards if we want to break a cycle. We use
 418          * a special marker for the beginning: we point to
 419          * ourselves. */
 420         j->marker = from ? from : j;
 421         j->generation = generation;
 422
 423         /* We assume that the dependencies are bidirectional, and
 424          * hence can ignore UNIT_AFTER */
 425         SET_FOREACH(u, j->unit->dependencies[UNIT_BEFORE], i) {
 426                 Job *o;
 427
 428                 /* Is there a job for this unit? */
 429                 o = hashmap_get(tr->jobs, u);
 430                 if (!o) {
 431                         /* Ok, there is no job for this in the
 432                          * transaction, but maybe there is already one
 433                          * running? */
 434                         o = u->job;
 435                         if (!o)
 436                                 continue;
 437                 }
 438
 439                 r = transaction_verify_order_one(tr, o, j, generation, e);
 440                 if (r < 0)
 441                         return r;
 442         }
 443
 444         /* Ok, let's backtrack, and remember that this entry is not on
 445          * our path anymore. */
 446         j->marker = NULL;
 447
 448         return 0;
 449 }
 450
 451 static int transaction_verify_order(Transaction *tr, unsigned *generation, sd_bus_error *e) {
 452         Job *j;
 453         int r;
 454         Iterator i;
 455         unsigned g;
 456
 457         assert(tr);
 458         assert(generation);
 459
 460         /* Check if the ordering graph is cyclic. If it is, try to fix
 461          * that up by dropping one of the jobs. */
 462
 463         g = (*generation)++;
 464
 465         HASHMAP_FOREACH(j, tr->jobs, i) {
 466                 r = transaction_verify_order_one(tr, j, NULL, g, e);
 467                 if (r < 0)
 468                         return r;
 469         }
 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, "Unit %s is not loaded properly.", unit->id);
 865
 866         if (type != JOB_STOP && unit->load_state == UNIT_ERROR) {
 867                 if (unit->load_error == -ENOENT || unit->manager->test_run)
 868                         return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED,
 869                                                  "Unit %s failed to load: %s.",
 870                                                  unit->id,
 871                                                  strerror(-unit->load_error));
 872                 else
 873                         return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED,
 874                                                  "Unit %s failed to load: %s. "
 875                                                  "See system logs and 'systemctl status %s' for details.",
 876                                                  unit->id,
 877                                                  strerror(-unit->load_error),
 878                                                  unit->id);
 879         }
 880
 881         if (type != JOB_STOP && unit->load_state == UNIT_NOT_FOUND)
 882                 return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED,
 883                                          "Unit %s failed to load: %s.",
 884                                          unit->id, strerror(-unit->load_error));
 885
 886         if (type != JOB_STOP && unit->load_state == UNIT_MASKED)
 887                 return sd_bus_error_setf(e, BUS_ERROR_UNIT_MASKED,
 888                                          "Unit %s is masked.", unit->id);
 889
 890         if (!unit_job_is_applicable(unit, type))
 891                 return sd_bus_error_setf(e, BUS_ERROR_JOB_TYPE_NOT_APPLICABLE,
 892                                          "Job type %s is not applicable for unit %s.",
 893                                          job_type_to_string(type), unit->id);
 894
 895
 896         /* First add the job. */
 897         ret = transaction_add_one_job(tr, type, unit, override, &is_new);
 898         if (!ret)
 899                 return -ENOMEM;
 900
 901         ret->ignore_order = ret->ignore_order || ignore_order;
 902
 903         /* Then, add a link to the job. */
 904         if (by) {
 905                 if (!job_dependency_new(by, ret, matters, conflicts))
 906                         return -ENOMEM;
 907         } else {
 908                 /* If the job has no parent job, it is the anchor job. */
 909                 assert(!tr->anchor_job);
 910                 tr->anchor_job = ret;
 911         }
 912
 913         if (is_new && !ignore_requirements && type != JOB_NOP) {
 914                 Set *following;
 915
 916                 /* If we are following some other unit, make sure we
 917                  * add all dependencies of everybody following. */
 918                 if (unit_following_set(ret->unit, &following) > 0) {
 919                         SET_FOREACH(dep, following, i) {
 920                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, false, override, false, false, ignore_order, e);
 921                                 if (r < 0) {
 922                                         log_unit_warning(dep, "Cannot add dependency job for, ignoring: %s", bus_error_message(e, r));
 923                                         sd_bus_error_free(e);
 924                                 }
 925                         }
 926
 927                         set_free(following);
 928                 }
 929
 930                 /* Finally, recursively add in all dependencies. */
 931                 if (type == JOB_START || type == JOB_RESTART) {
 932                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUIRES], i) {
 933                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, override, false, false, ignore_order, e);
 934                                 if (r < 0) {
 935                                         if (r != -EBADR)
 936                                                 goto fail;
 937
 938                                         sd_bus_error_free(e);
 939                                 }
 940                         }
 941
 942                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_BINDS_TO], i) {
 943                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, override, false, false, ignore_order, e);
 944                                 if (r < 0) {
 945                                         if (r != -EBADR)
 946                                                 goto fail;
 947
 948                                         sd_bus_error_free(e);
 949                                 }
 950                         }
 951
 952                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUIRES_OVERRIDABLE], i) {
 953                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, !override, override, false, false, ignore_order, e);
 954                                 if (r < 0) {
 955                                         log_unit_full(dep,
 956                                                       r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, r,
 957                                                       "Cannot add dependency job, ignoring: %s",
 958                                                       bus_error_message(e, r));
 959                                         sd_bus_error_free(e);
 960                                 }
 961                         }
 962
 963                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_WANTS], i) {
 964                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, false, false, false, false, ignore_order, e);
 965                                 if (r < 0) {
 966                                         log_unit_full(dep,
 967                                                       r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, r,
 968                                                       "Cannot add dependency job, ignoring: %s",
 969                                                       bus_error_message(e, r));
 970                                         sd_bus_error_free(e);
 971                                 }
 972                         }
 973
 974                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUISITE], i) {
 975                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, true, override, false, false, ignore_order, e);
 976                                 if (r < 0) {
 977                                         if (r != -EBADR)
 978                                                 goto fail;
 979
 980                                         sd_bus_error_free(e);
 981                                 }
 982                         }
 983
 984                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUISITE_OVERRIDABLE], i) {
 985                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, !override, override, false, false, ignore_order, e);
 986                                 if (r < 0) {
 987                                         log_unit_full(dep,
 988                                                       r == -EADDRNOTAVAIL ? LOG_DEBUG : LOG_WARNING, r,
 989                                                       "Cannot add dependency job, ignoring: %s",
 990                                                       bus_error_message(e, r));
 991                                         sd_bus_error_free(e);
 992                                 }
 993                         }
 994
 995                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONFLICTS], i) {
 996                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, true, override, true, false, ignore_order, e);
 997                                 if (r < 0) {
 998                                         if (r != -EBADR)
 999                                                 goto fail;
1000
1001                                         sd_bus_error_free(e);
1002                                 }
1003                         }
1004
1005                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONFLICTED_BY], i) {
1006                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, false, override, false, false, ignore_order, e);
1007                                 if (r < 0) {
1008                                         log_unit_warning(dep,
1009                                                          "Cannot add dependency job, ignoring: %s",
1010                                                          bus_error_message(e, r));
1011                                         sd_bus_error_free(e);
1012                                 }
1013                         }
1014
1015                 }
1016
1017                 if (type == JOB_STOP || type == JOB_RESTART) {
1018                         static const UnitDependency propagate_deps[] = {
1019                                 UNIT_REQUIRED_BY,
1020                                 UNIT_REQUISITE_OF,
1021                                 UNIT_BOUND_BY,
1022                                 UNIT_CONSISTS_OF,
1023                         };
1024
1025                         JobType ptype;
1026                         unsigned j;
1027
1028                         /* We propagate STOP as STOP, but RESTART only
1029                          * as TRY_RESTART, in order not to start
1030                          * dependencies that are not around. */
1031                         ptype = type == JOB_RESTART ? JOB_TRY_RESTART : type;
1032
1033                         for (j = 0; j < ELEMENTSOF(propagate_deps); j++)
1034                                 SET_FOREACH(dep, ret->unit->dependencies[propagate_deps[j]], i) {
1035                                         JobType nt;
1036
1037                                         nt = job_type_collapse(ptype, dep);
1038                                         if (nt == JOB_NOP)
1039                                                 continue;
1040
1041                                         r = transaction_add_job_and_dependencies(tr, nt, dep, ret, true, override, false, false, ignore_order, e);
1042                                         if (r < 0) {
1043                                                 if (r != -EBADR)
1044                                                         goto fail;
1045
1046                                                 sd_bus_error_free(e);
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_unit_warning(dep,
1057                                                          "Cannot add dependency reload job, ignoring: %s",
1058                                                          bus_error_message(e, r));
1059                                         sd_bus_error_free(e);
1060                                 }
1061                         }
1062                 }
1063
1064                 /* JOB_VERIFY_STARTED require no dependency handling */
1065         }
1066
1067         return 0;
1068
1069 fail:
1070         return r;
1071 }
1072
1073 int transaction_add_isolate_jobs(Transaction *tr, Manager *m) {
1074         Iterator i;
1075         Unit *u;
1076         char *k;
1077         int r;
1078
1079         assert(tr);
1080         assert(m);
1081
1082         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
1083
1084                 /* ignore aliases */
1085                 if (u->id != k)
1086                         continue;
1087
1088                 if (u->ignore_on_isolate)
1089                         continue;
1090
1091                 /* No need to stop inactive jobs */
1092                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(u)) && !u->job)
1093                         continue;
1094
1095                 /* Is there already something listed for this? */
1096                 if (hashmap_get(tr->jobs, u))
1097                         continue;
1098
1099                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, u, tr->anchor_job, true, false, false, false, false, NULL);
1100                 if (r < 0)
1101                         log_unit_warning_errno(u, r, "Cannot add isolate job, ignoring: %m");
1102         }
1103
1104         return 0;
1105 }
1106
1107 Transaction *transaction_new(bool irreversible) {
1108         Transaction *tr;
1109
1110         tr = new0(Transaction, 1);
1111         if (!tr)
1112                 return NULL;
1113
1114         tr->jobs = hashmap_new(NULL);
1115         if (!tr->jobs) {
1116                 free(tr);
1117                 return NULL;
1118         }
1119
1120         tr->irreversible = irreversible;
1121
1122         return tr;
1123 }
1124
1125 void transaction_free(Transaction *tr) {
1126         assert(hashmap_isempty(tr->jobs));
1127         hashmap_free(tr->jobs);
1128         free(tr);
1129 }