src/core/transaction.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <fcntl.h>
  21 #include <unistd.h>
  22
  23 #include "alloc-util.h"
  24 #include "bus-common-errors.h"
  25 #include "bus-error.h"
  26 #include "terminal-util.h"
  27 #include "transaction.h"
  28 #include "dbus-unit.h"
  29
  30 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies);
  31
  32 static void transaction_delete_job(Transaction *tr, Job *j, bool delete_dependencies) {
  33         assert(tr);
  34         assert(j);
  35
  36         /* Deletes one job from the transaction */
  37
  38         transaction_unlink_job(tr, j, delete_dependencies);
  39
  40         job_free(j);
  41 }
  42
  43 static void transaction_delete_unit(Transaction *tr, Unit *u) {
  44         Job *j;
  45
  46         /* Deletes all jobs associated with a certain unit from the
  47          * transaction */
  48
  49         while ((j = hashmap_get(tr->jobs, u)))
  50                 transaction_delete_job(tr, j, true);
  51 }
  52
  53 void transaction_abort(Transaction *tr) {
  54         Job *j;
  55
  56         assert(tr);
  57
  58         while ((j = hashmap_first(tr->jobs)))
  59                 transaction_delete_job(tr, j, false);
  60
  61         assert(hashmap_isempty(tr->jobs));
  62 }
  63
  64 static void transaction_find_jobs_that_matter_to_anchor(Job *j, unsigned generation) {
  65         JobDependency *l;
  66
  67         /* A recursive sweep through the graph that marks all units
  68          * that matter to the anchor job, i.e. are directly or
  69          * indirectly a dependency of the anchor job via paths that
  70          * are fully marked as mattering. */
  71
  72         j->matters_to_anchor = true;
  73         j->generation = generation;
  74
  75         LIST_FOREACH(subject, l, j->subject_list) {
  76
  77                 /* This link does not matter */
  78                 if (!l->matters)
  79                         continue;
  80
  81                 /* This unit has already been marked */
  82                 if (l->object->generation == generation)
  83                         continue;
  84
  85                 transaction_find_jobs_that_matter_to_anchor(l->object, generation);
  86         }
  87 }
  88
  89 static void transaction_merge_and_delete_job(Transaction *tr, Job *j, Job *other, JobType t) {
  90         JobDependency *l, *last;
  91
  92         assert(j);
  93         assert(other);
  94         assert(j->unit == other->unit);
  95         assert(!j->installed);
  96
  97         /* Merges 'other' into 'j' and then deletes 'other'. */
  98
  99         j->type = t;
 100         j->state = JOB_WAITING;
 101         j->irreversible = j->irreversible || other->irreversible;
 102         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
 103
 104         /* Patch us in as new owner of the JobDependency objects */
 105         last = NULL;
 106         LIST_FOREACH(subject, l, other->subject_list) {
 107                 assert(l->subject == other);
 108                 l->subject = j;
 109                 last = l;
 110         }
 111
 112         /* Merge both lists */
 113         if (last) {
 114                 last->subject_next = j->subject_list;
 115                 if (j->subject_list)
 116                         j->subject_list->subject_prev = last;
 117                 j->subject_list = other->subject_list;
 118         }
 119
 120         /* Patch us in as new owner of the JobDependency objects */
 121         last = NULL;
 122         LIST_FOREACH(object, l, other->object_list) {
 123                 assert(l->object == other);
 124                 l->object = j;
 125                 last = l;
 126         }
 127
 128         /* Merge both lists */
 129         if (last) {
 130                 last->object_next = j->object_list;
 131                 if (j->object_list)
 132                         j->object_list->object_prev = last;
 133                 j->object_list = other->object_list;
 134         }
 135
 136         /* Kill the other job */
 137         other->subject_list = NULL;
 138         other->object_list = NULL;
 139         transaction_delete_job(tr, other, true);
 140 }
 141
 142 _pure_ static bool job_is_conflicted_by(Job *j) {
 143         JobDependency *l;
 144
 145         assert(j);
 146
 147         /* Returns true if this job is pulled in by a least one
 148          * ConflictedBy dependency. */
 149
 150         LIST_FOREACH(object, l, j->object_list)
 151                 if (l->conflicts)
 152                         return true;
 153
 154         return false;
 155 }
 156
 157 static int delete_one_unmergeable_job(Transaction *tr, Job *j) {
 158         Job *k;
 159
 160         assert(j);
 161
 162         /* Tries to delete one item in the linked list
 163          * j->transaction_next->transaction_next->... that conflicts
 164          * with another one, in an attempt to make an inconsistent
 165          * transaction work. */
 166
 167         /* We rely here on the fact that if a merged with b does not
 168          * merge with c, either a or b merge with c neither */
 169         LIST_FOREACH(transaction, j, j)
 170                 LIST_FOREACH(transaction, k, j->transaction_next) {
 171                         Job *d;
 172
 173                         /* Is this one mergeable? Then skip it */
 174                         if (job_type_is_mergeable(j->type, k->type))
 175                                 continue;
 176
 177                         /* Ok, we found two that conflict, let's see if we can
 178                          * drop one of them */
 179                         if (!j->matters_to_anchor && !k->matters_to_anchor) {
 180
 181                                 /* Both jobs don't matter, so let's
 182                                  * find the one that is smarter to
 183                                  * remove. Let's think positive and
 184                                  * rather remove stops then starts --
 185                                  * except if something is being
 186                                  * stopped because it is conflicted by
 187                                  * another unit in which case we
 188                                  * rather remove the start. */
 189
 190                                 log_unit_debug(j->unit,
 191                                                "Looking at job %s/%s conflicted_by=%s",
 192                                                j->unit->id, job_type_to_string(j->type),
 193                                                yes_no(j->type == JOB_STOP && job_is_conflicted_by(j)));
 194                                 log_unit_debug(k->unit,
 195                                                "Looking at job %s/%s conflicted_by=%s",
 196                                                k->unit->id, job_type_to_string(k->type),
 197                                                yes_no(k->type == JOB_STOP && job_is_conflicted_by(k)));
 198
 199                                 if (j->type == JOB_STOP) {
 200
 201                                         if (job_is_conflicted_by(j))
 202                                                 d = k;
 203                                         else
 204                                                 d = j;
 205
 206                                 } else if (k->type == JOB_STOP) {
 207
 208                                         if (job_is_conflicted_by(k))
 209                                                 d = j;
 210                                         else
 211                                                 d = k;
 212                                 } else
 213                                         d = j;
 214
 215                         } else if (!j->matters_to_anchor)
 216                                 d = j;
 217                         else if (!k->matters_to_anchor)
 218                                 d = k;
 219                         else
 220                                 return -ENOEXEC;
 221
 222                         /* Ok, we can drop one, so let's do so. */
 223                         log_unit_debug(d->unit,
 224                                        "Fixing conflicting jobs %s/%s,%s/%s by deleting job %s/%s",
 225                                        j->unit->id, job_type_to_string(j->type),
 226                                        k->unit->id, job_type_to_string(k->type),
 227                                        d->unit->id, job_type_to_string(d->type));
 228                         transaction_delete_job(tr, d, true);
 229                         return 0;
 230                 }
 231
 232         return -EINVAL;
 233 }
 234
 235 static int transaction_merge_jobs(Transaction *tr, sd_bus_error *e) {
 236         Job *j;
 237         Iterator i;
 238         int r;
 239
 240         assert(tr);
 241
 242         /* First step, check whether any of the jobs for one specific
 243          * task conflict. If so, try to drop one of them. */
 244         HASHMAP_FOREACH(j, tr->jobs, i) {
 245                 JobType t;
 246                 Job *k;
 247
 248                 t = j->type;
 249                 LIST_FOREACH(transaction, k, j->transaction_next) {
 250                         if (job_type_merge_and_collapse(&t, k->type, j->unit) >= 0)
 251                                 continue;
 252
 253                         /* OK, we could not merge all jobs for this
 254                          * action. Let's see if we can get rid of one
 255                          * of them */
 256
 257                         r = delete_one_unmergeable_job(tr, j);
 258                         if (r >= 0)
 259                                 /* Ok, we managed to drop one, now
 260                                  * let's ask our callers to call us
 261                                  * again after garbage collecting */
 262                                 return -EAGAIN;
 263
 264                         /* We couldn't merge anything. Failure */
 265                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_JOBS_CONFLICTING,
 266                                                  "Transaction contains conflicting jobs '%s' and '%s' for %s. "
 267                                                  "Probably contradicting requirement dependencies configured.",
 268                                                  job_type_to_string(t),
 269                                                  job_type_to_string(k->type),
 270                                                  k->unit->id);
 271                 }
 272         }
 273
 274         /* Second step, merge the jobs. */
 275         HASHMAP_FOREACH(j, tr->jobs, i) {
 276                 JobType t = j->type;
 277                 Job *k;
 278
 279                 /* Merge all transaction jobs for j->unit */
 280                 LIST_FOREACH(transaction, k, j->transaction_next)
 281                         assert_se(job_type_merge_and_collapse(&t, k->type, j->unit) == 0);
 282
 283                 while ((k = j->transaction_next)) {
 284                         if (tr->anchor_job == k) {
 285                                 transaction_merge_and_delete_job(tr, k, j, t);
 286                                 j = k;
 287                         } else
 288                                 transaction_merge_and_delete_job(tr, j, k, t);
 289                 }
 290
 291                 assert(!j->transaction_next);
 292                 assert(!j->transaction_prev);
 293         }
 294
 295         return 0;
 296 }
 297
 298 static void transaction_drop_redundant(Transaction *tr) {
 299         Job *j;
 300         Iterator i;
 301
 302         /* Goes through the transaction and removes all jobs of the units
 303          * whose jobs are all noops. If not all of a unit's jobs are
 304          * redundant, they are kept. */
 305
 306         assert(tr);
 307
 308 rescan:
 309         HASHMAP_FOREACH(j, tr->jobs, i) {
 310                 Job *k;
 311
 312                 LIST_FOREACH(transaction, k, j) {
 313
 314                         if (tr->anchor_job == k ||
 315                             !job_type_is_redundant(k->type, unit_active_state(k->unit)) ||
 316                             (k->unit->job && job_type_is_conflicting(k->type, k->unit->job->type)))
 317                                 goto next_unit;
 318                 }
 319
 320                 /* log_debug("Found redundant job %s/%s, dropping.", j->unit->id, job_type_to_string(j->type)); */
 321                 transaction_delete_job(tr, j, false);
 322                 goto rescan;
 323         next_unit:;
 324         }
 325 }
 326
 327 _pure_ static bool unit_matters_to_anchor(Unit *u, Job *j) {
 328         assert(u);
 329         assert(!j->transaction_prev);
 330
 331         /* Checks whether at least one of the jobs for this unit
 332          * matters to the anchor. */
 333
 334         LIST_FOREACH(transaction, j, j)
 335                 if (j->matters_to_anchor)
 336                         return true;
 337
 338         return false;
 339 }
 340
 341 static char* merge_unit_ids(const char* unit_log_field, char **pairs) {
 342         char **unit_id, **job_type, *ans = NULL;
 343         size_t alloc = 0, size = 0, next;
 344
 345         STRV_FOREACH_PAIR(unit_id, job_type, pairs) {
 346                 next = strlen(unit_log_field) + strlen(*unit_id);
 347                 if (!GREEDY_REALLOC(ans, alloc, size + next + 1)) {
 348                         free(ans);
 349                         return NULL;
 350                 }
 351
 352                 sprintf(ans + size, "%s%s", unit_log_field, *unit_id);
 353                 if (*(unit_id+1))
 354                         ans[size + next] =  '\n';
 355                 size += next + 1;
 356         }
 357
 358         return ans;
 359 }
 360
 361 static int transaction_verify_order_one(Transaction *tr, Job *j, Job *from, unsigned generation, sd_bus_error *e) {
 362         Iterator i;
 363         Unit *u;
 364         int r;
 365
 366         assert(tr);
 367         assert(j);
 368         assert(!j->transaction_prev);
 369
 370         /* Does a recursive sweep through the ordering graph, looking
 371          * for a cycle. If we find a cycle we try to break it. */
 372
 373         /* Have we seen this before? */
 374         if (j->generation == generation) {
 375                 Job *k, *delete = NULL;
 376                 _cleanup_free_ char **array = NULL, *unit_ids = NULL;
 377                 char **unit_id, **job_type;
 378
 379                 /* If the marker is NULL we have been here already and
 380                  * decided the job was loop-free from here. Hence
 381                  * shortcut things and return right-away. */
 382                 if (!j->marker)
 383                         return 0;
 384
 385                 /* So, the marker is not NULL and we already have been here. We have
 386                  * a cycle. Let's try to break it. We go backwards in our path and
 387                  * try to find a suitable job to remove. We use the marker to find
 388                  * our way back, since smart how we are we stored our way back in
 389                  * there. */
 390
 391                 for (k = from; k; k = ((k->generation == generation && k->marker != k) ? k->marker : NULL)) {
 392
 393                         /* For logging below */
 394                         if (strv_push_pair(&array, k->unit->id, (char*) job_type_to_string(k->type)) < 0)
 395                                 log_oom();
 396
 397                         if (!delete && hashmap_get(tr->jobs, k->unit) && !unit_matters_to_anchor(k->unit, k))
 398                                 /* Ok, we can drop this one, so let's do so. */
 399                                 delete = k;
 400
 401                         /* Check if this in fact was the beginning of the cycle */
 402                         if (k == j)
 403                                 break;
 404                 }
 405
 406                 unit_ids = merge_unit_ids(j->manager->unit_log_field, array); /* ignore error */
 407
 408                 STRV_FOREACH_PAIR(unit_id, job_type, array)
 409                         /* logging for j not k here to provide a consistent narrative */
 410                         log_struct(LOG_WARNING,
 411                                    "MESSAGE=%s: Found %s on %s/%s",
 412                                    j->unit->id,
 413                                    unit_id == array ? "ordering cycle" : "dependency",
 414                                    *unit_id, *job_type,
 415                                    unit_ids, NULL);
 416
 417                 if (delete) {
 418                         const char *status;
 419                         /* logging for j not k here to provide a consistent narrative */
 420                         log_struct(LOG_ERR,
 421                                    "MESSAGE=%s: Job %s/%s deleted to break ordering cycle starting with %s/%s",
 422                                    j->unit->id, delete->unit->id, job_type_to_string(delete->type),
 423                                    j->unit->id, job_type_to_string(j->type),
 424                                    unit_ids, NULL);
 425
 426                         if (log_get_show_color())
 427                                 status = ANSI_HIGHLIGHT_RED " SKIP " ANSI_NORMAL;
 428                         else
 429                                 status = " SKIP ";
 430
 431                         unit_status_printf(delete->unit, status,
 432                                            "Ordering cycle found, skipping %s");
 433                         transaction_delete_unit(tr, delete->unit);
 434                         return -EAGAIN;
 435                 }
 436
 437                 log_struct(LOG_ERR,
 438                            "MESSAGE=%s: Unable to break cycle starting with %s/%s",
 439                            j->unit->id, j->unit->id, job_type_to_string(j->type),
 440                            unit_ids, NULL);
 441
 442                 return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_ORDER_IS_CYCLIC,
 443                                          "Transaction order is cyclic. See system logs for details.");
 444         }
 445
 446         /* Make the marker point to where we come from, so that we can
 447          * find our way backwards if we want to break a cycle. We use
 448          * a special marker for the beginning: we point to
 449          * ourselves. */
 450         j->marker = from ? from : j;
 451         j->generation = generation;
 452
 453         /* We assume that the dependencies are bidirectional, and
 454          * hence can ignore UNIT_AFTER */
 455         SET_FOREACH(u, j->unit->dependencies[UNIT_BEFORE], i) {
 456                 Job *o;
 457
 458                 /* Is there a job for this unit? */
 459                 o = hashmap_get(tr->jobs, u);
 460                 if (!o) {
 461                         /* Ok, there is no job for this in the
 462                          * transaction, but maybe there is already one
 463                          * running? */
 464                         o = u->job;
 465                         if (!o)
 466                                 continue;
 467                 }
 468
 469                 r = transaction_verify_order_one(tr, o, j, generation, e);
 470                 if (r < 0)
 471                         return r;
 472         }
 473
 474         /* Ok, let's backtrack, and remember that this entry is not on
 475          * our path anymore. */
 476         j->marker = NULL;
 477
 478         return 0;
 479 }
 480
 481 static int transaction_verify_order(Transaction *tr, unsigned *generation, sd_bus_error *e) {
 482         Job *j;
 483         int r;
 484         Iterator i;
 485         unsigned g;
 486
 487         assert(tr);
 488         assert(generation);
 489
 490         /* Check if the ordering graph is cyclic. If it is, try to fix
 491          * that up by dropping one of the jobs. */
 492
 493         g = (*generation)++;
 494
 495         HASHMAP_FOREACH(j, tr->jobs, i) {
 496                 r = transaction_verify_order_one(tr, j, NULL, g, e);
 497                 if (r < 0)
 498                         return r;
 499         }
 500
 501         return 0;
 502 }
 503
 504 static void transaction_collect_garbage(Transaction *tr) {
 505         Iterator i;
 506         Job *j;
 507
 508         assert(tr);
 509
 510         /* Drop jobs that are not required by any other job */
 511
 512 rescan:
 513         HASHMAP_FOREACH(j, tr->jobs, i) {
 514                 if (tr->anchor_job == j || j->object_list) {
 515                         /* log_debug("Keeping job %s/%s because of %s/%s", */
 516                         /*           j->unit->id, job_type_to_string(j->type), */
 517                         /*           j->object_list->subject ? j->object_list->subject->unit->id : "root", */
 518                         /*           j->object_list->subject ? job_type_to_string(j->object_list->subject->type) : "root"); */
 519                         continue;
 520                 }
 521
 522                 /* log_debug("Garbage collecting job %s/%s", j->unit->id, job_type_to_string(j->type)); */
 523                 transaction_delete_job(tr, j, true);
 524                 goto rescan;
 525         }
 526 }
 527
 528 static int transaction_is_destructive(Transaction *tr, JobMode mode, sd_bus_error *e) {
 529         Iterator i;
 530         Job *j;
 531
 532         assert(tr);
 533
 534         /* Checks whether applying this transaction means that
 535          * existing jobs would be replaced */
 536
 537         HASHMAP_FOREACH(j, tr->jobs, i) {
 538
 539                 /* Assume merged */
 540                 assert(!j->transaction_prev);
 541                 assert(!j->transaction_next);
 542
 543                 if (j->unit->job && (mode == JOB_FAIL || j->unit->job->irreversible) &&
 544                     job_type_is_conflicting(j->unit->job->type, j->type))
 545                         return sd_bus_error_setf(e, BUS_ERROR_TRANSACTION_IS_DESTRUCTIVE,
 546                                                  "Transaction is destructive.");
 547         }
 548
 549         return 0;
 550 }
 551
 552 static void transaction_minimize_impact(Transaction *tr) {
 553         Job *j;
 554         Iterator i;
 555
 556         assert(tr);
 557
 558         /* Drops all unnecessary jobs that reverse already active jobs
 559          * or that stop a running service. */
 560
 561 rescan:
 562         HASHMAP_FOREACH(j, tr->jobs, i) {
 563                 LIST_FOREACH(transaction, j, j) {
 564                         bool stops_running_service, changes_existing_job;
 565
 566                         /* If it matters, we shouldn't drop it */
 567                         if (j->matters_to_anchor)
 568                                 continue;
 569
 570                         /* Would this stop a running service?
 571                          * Would this change an existing job?
 572                          * If so, let's drop this entry */
 573
 574                         stops_running_service =
 575                                 j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 576
 577                         changes_existing_job =
 578                                 j->unit->job &&
 579                                 job_type_is_conflicting(j->type, j->unit->job->type);
 580
 581                         if (!stops_running_service && !changes_existing_job)
 582                                 continue;
 583
 584                         if (stops_running_service)
 585                                 log_unit_debug(j->unit,
 586                                                "%s/%s would stop a running service.",
 587                                                j->unit->id, job_type_to_string(j->type));
 588
 589                         if (changes_existing_job)
 590                                 log_unit_debug(j->unit,
 591                                                "%s/%s would change existing job.",
 592                                                j->unit->id, job_type_to_string(j->type));
 593
 594                         /* Ok, let's get rid of this */
 595                         log_unit_debug(j->unit,
 596                                        "Deleting %s/%s to minimize impact.",
 597                                        j->unit->id, job_type_to_string(j->type));
 598
 599                         transaction_delete_job(tr, j, true);
 600                         goto rescan;
 601                 }
 602         }
 603 }
 604
 605 static int transaction_apply(Transaction *tr, Manager *m, JobMode mode) {
 606         Iterator i;
 607         Job *j;
 608         int r;
 609
 610         /* Moves the transaction jobs to the set of active jobs */
 611
 612         if (IN_SET(mode, JOB_ISOLATE, JOB_FLUSH)) {
 613
 614                 /* When isolating first kill all installed jobs which
 615                  * aren't part of the new transaction */
 616                 HASHMAP_FOREACH(j, m->jobs, i) {
 617                         assert(j->installed);
 618
 619                         if (j->unit->ignore_on_isolate)
 620                                 continue;
 621
 622                         if (hashmap_get(tr->jobs, j->unit))
 623                                 continue;
 624
 625                         /* Not invalidating recursively. Avoids triggering
 626                          * OnFailure= actions of dependent jobs. Also avoids
 627                          * invalidating our iterator. */
 628                         job_finish_and_invalidate(j, JOB_CANCELED, false, false);
 629                 }
 630         }
 631
 632         HASHMAP_FOREACH(j, tr->jobs, i) {
 633                 /* Assume merged */
 634                 assert(!j->transaction_prev);
 635                 assert(!j->transaction_next);
 636
 637                 r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j);
 638                 if (r < 0)
 639                         goto rollback;
 640         }
 641
 642         while ((j = hashmap_steal_first(tr->jobs))) {
 643                 Job *installed_job;
 644
 645                 /* Clean the job dependencies */
 646                 transaction_unlink_job(tr, j, false);
 647
 648                 installed_job = job_install(j);
 649                 if (installed_job != j) {
 650                         /* j has been merged into a previously installed job */
 651                         if (tr->anchor_job == j)
 652                                 tr->anchor_job = installed_job;
 653                         hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 654                         job_free(j);
 655                         j = installed_job;
 656                 }
 657
 658                 job_add_to_run_queue(j);
 659                 job_add_to_dbus_queue(j);
 660                 job_start_timer(j, false);
 661                 job_shutdown_magic(j);
 662         }
 663
 664         return 0;
 665
 666 rollback:
 667
 668         HASHMAP_FOREACH(j, tr->jobs, i)
 669                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 670
 671         return r;
 672 }
 673
 674 int transaction_activate(Transaction *tr, Manager *m, JobMode mode, sd_bus_error *e) {
 675         Iterator i;
 676         Job *j;
 677         int r;
 678         unsigned generation = 1;
 679
 680         assert(tr);
 681
 682         /* This applies the changes recorded in tr->jobs to
 683          * the actual list of jobs, if possible. */
 684
 685         /* Reset the generation counter of all installed jobs. The detection of cycles
 686          * looks at installed jobs. If they had a non-zero generation from some previous
 687          * walk of the graph, the algorithm would break. */
 688         HASHMAP_FOREACH(j, m->jobs, i)
 689                 j->generation = 0;
 690
 691         /* First step: figure out which jobs matter */
 692         transaction_find_jobs_that_matter_to_anchor(tr->anchor_job, generation++);
 693
 694         /* Second step: Try not to stop any running services if
 695          * we don't have to. Don't try to reverse running
 696          * jobs if we don't have to. */
 697         if (mode == JOB_FAIL)
 698                 transaction_minimize_impact(tr);
 699
 700         /* Third step: Drop redundant jobs */
 701         transaction_drop_redundant(tr);
 702
 703         for (;;) {
 704                 /* Fourth step: Let's remove unneeded jobs that might
 705                  * be lurking. */
 706                 if (mode != JOB_ISOLATE)
 707                         transaction_collect_garbage(tr);
 708
 709                 /* Fifth step: verify order makes sense and correct
 710                  * cycles if necessary and possible */
 711                 r = transaction_verify_order(tr, &generation, e);
 712                 if (r >= 0)
 713                         break;
 714
 715                 if (r != -EAGAIN) {
 716                         log_warning("Requested transaction contains an unfixable cyclic ordering dependency: %s", bus_error_message(e, r));
 717                         return r;
 718                 }
 719
 720                 /* Let's see if the resulting transaction ordering
 721                  * graph is still cyclic... */
 722         }
 723
 724         for (;;) {
 725                 /* Sixth step: let's drop unmergeable entries if
 726                  * necessary and possible, merge entries we can
 727                  * merge */
 728                 r = transaction_merge_jobs(tr, e);
 729                 if (r >= 0)
 730                         break;
 731
 732                 if (r != -EAGAIN) {
 733                         log_warning("Requested transaction contains unmergeable jobs: %s", bus_error_message(e, r));
 734                         return r;
 735                 }
 736
 737                 /* Seventh step: an entry got dropped, let's garbage
 738                  * collect its dependencies. */
 739                 if (mode != JOB_ISOLATE)
 740                         transaction_collect_garbage(tr);
 741
 742                 /* Let's see if the resulting transaction still has
 743                  * unmergeable entries ... */
 744         }
 745
 746         /* Eights step: Drop redundant jobs again, if the merging now allows us to drop more. */
 747         transaction_drop_redundant(tr);
 748
 749         /* Ninth step: check whether we can actually apply this */
 750         r = transaction_is_destructive(tr, mode, e);
 751         if (r < 0) {
 752                 log_notice("Requested transaction contradicts existing jobs: %s", bus_error_message(e, r));
 753                 return r;
 754         }
 755
 756         /* Tenth step: apply changes */
 757         r = transaction_apply(tr, m, mode);
 758         if (r < 0)
 759                 return log_warning_errno(r, "Failed to apply transaction: %m");
 760
 761         assert(hashmap_isempty(tr->jobs));
 762
 763         if (!hashmap_isempty(m->jobs)) {
 764                 /* Are there any jobs now? Then make sure we have the
 765                  * idle pipe around. We don't really care too much
 766                  * whether this works or not, as the idle pipe is a
 767                  * feature for cosmetics, not actually useful for
 768                  * anything beyond that. */
 769
 770                 if (m->idle_pipe[0] < 0 && m->idle_pipe[1] < 0 &&
 771                     m->idle_pipe[2] < 0 && m->idle_pipe[3] < 0) {
 772                         (void) pipe2(m->idle_pipe, O_NONBLOCK|O_CLOEXEC);
 773                         (void) pipe2(m->idle_pipe + 2, O_NONBLOCK|O_CLOEXEC);
 774                 }
 775         }
 776
 777         return 0;
 778 }
 779
 780 static Job* transaction_add_one_job(Transaction *tr, JobType type, Unit *unit, bool *is_new) {
 781         Job *j, *f;
 782
 783         assert(tr);
 784         assert(unit);
 785
 786         /* Looks for an existing prospective job and returns that. If
 787          * it doesn't exist it is created and added to the prospective
 788          * jobs list. */
 789
 790         f = hashmap_get(tr->jobs, unit);
 791
 792         LIST_FOREACH(transaction, j, f) {
 793                 assert(j->unit == unit);
 794
 795                 if (j->type == type) {
 796                         if (is_new)
 797                                 *is_new = false;
 798                         return j;
 799                 }
 800         }
 801
 802         j = job_new(unit, type);
 803         if (!j)
 804                 return NULL;
 805
 806         j->generation = 0;
 807         j->marker = NULL;
 808         j->matters_to_anchor = false;
 809         j->irreversible = tr->irreversible;
 810
 811         LIST_PREPEND(transaction, f, j);
 812
 813         if (hashmap_replace(tr->jobs, unit, f) < 0) {
 814                 LIST_REMOVE(transaction, f, j);
 815                 job_free(j);
 816                 return NULL;
 817         }
 818
 819         if (is_new)
 820                 *is_new = true;
 821
 822         /* log_debug("Added job %s/%s to transaction.", unit->id, job_type_to_string(type)); */
 823
 824         return j;
 825 }
 826
 827 static void transaction_unlink_job(Transaction *tr, Job *j, bool delete_dependencies) {
 828         assert(tr);
 829         assert(j);
 830
 831         if (j->transaction_prev)
 832                 j->transaction_prev->transaction_next = j->transaction_next;
 833         else if (j->transaction_next)
 834                 hashmap_replace(tr->jobs, j->unit, j->transaction_next);
 835         else
 836                 hashmap_remove_value(tr->jobs, j->unit, j);
 837
 838         if (j->transaction_next)
 839                 j->transaction_next->transaction_prev = j->transaction_prev;
 840
 841         j->transaction_prev = j->transaction_next = NULL;
 842
 843         while (j->subject_list)
 844                 job_dependency_free(j->subject_list);
 845
 846         while (j->object_list) {
 847                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 848
 849                 job_dependency_free(j->object_list);
 850
 851                 if (other && delete_dependencies) {
 852                         log_unit_debug(other->unit,
 853                                        "Deleting job %s/%s as dependency of job %s/%s",
 854                                        other->unit->id, job_type_to_string(other->type),
 855                                        j->unit->id, job_type_to_string(j->type));
 856                         transaction_delete_job(tr, other, delete_dependencies);
 857                 }
 858         }
 859 }
 860
 861 void transaction_add_propagate_reload_jobs(Transaction *tr, Unit *unit, Job *by, bool ignore_order, sd_bus_error *e) {
 862         Iterator i;
 863         Unit *dep;
 864         JobType nt;
 865         int r;
 866
 867         assert(tr);
 868         assert(unit);
 869
 870         SET_FOREACH(dep, unit->dependencies[UNIT_PROPAGATES_RELOAD_TO], i) {
 871                 nt = job_type_collapse(JOB_TRY_RELOAD, dep);
 872                 if (nt == JOB_NOP)
 873                         continue;
 874
 875                 r = transaction_add_job_and_dependencies(tr, nt, dep, by, false, false, false, ignore_order, e);
 876                 if (r < 0) {
 877                         log_unit_warning(dep,
 878                                          "Cannot add dependency reload job, ignoring: %s",
 879                                          bus_error_message(e, r));
 880                         sd_bus_error_free(e);
 881                 }
 882         }
 883 }
 884
 885 int transaction_add_job_and_dependencies(
 886                 Transaction *tr,
 887                 JobType type,
 888                 Unit *unit,
 889                 Job *by,
 890                 bool matters,
 891                 bool conflicts,
 892                 bool ignore_requirements,
 893                 bool ignore_order,
 894                 sd_bus_error *e) {
 895         Job *ret;
 896         Iterator i;
 897         Unit *dep;
 898         int r;
 899         bool is_new;
 900
 901         assert(tr);
 902         assert(type < _JOB_TYPE_MAX);
 903         assert(type < _JOB_TYPE_MAX_IN_TRANSACTION);
 904         assert(unit);
 905
 906         /* Before adding jobs for this unit, let's ensure that its state has been loaded
 907          * This matters when jobs are spawned as part of coldplugging itself (see e. g. path_coldplug()).
 908          * This way, we "recursively" coldplug units, ensuring that we do not look at state of
 909          * not-yet-coldplugged units. */
 910         if (MANAGER_IS_RELOADING(unit->manager))
 911                 unit_coldplug(unit);
 912
 913         /* log_debug("Pulling in %s/%s from %s/%s", */
 914         /*           unit->id, job_type_to_string(type), */
 915         /*           by ? by->unit->id : "NA", */
 916         /*           by ? job_type_to_string(by->type) : "NA"); */
 917
 918         if (!IN_SET(unit->load_state, UNIT_LOADED, UNIT_ERROR, UNIT_NOT_FOUND, UNIT_MASKED))
 919                 return sd_bus_error_setf(e, BUS_ERROR_LOAD_FAILED, "Unit %s is not loaded properly.", unit->id);
 920
 921         if (type != JOB_STOP) {
 922                 r = bus_unit_check_load_state(unit, e);
 923                 if (r < 0)
 924                         return r;
 925         }
 926
 927         if (!unit_job_is_applicable(unit, type))
 928                 return sd_bus_error_setf(e, BUS_ERROR_JOB_TYPE_NOT_APPLICABLE,
 929                                          "Job type %s is not applicable for unit %s.",
 930                                          job_type_to_string(type), unit->id);
 931
 932
 933         /* First add the job. */
 934         ret = transaction_add_one_job(tr, type, unit, &is_new);
 935         if (!ret)
 936                 return -ENOMEM;
 937
 938         ret->ignore_order = ret->ignore_order || ignore_order;
 939
 940         /* Then, add a link to the job. */
 941         if (by) {
 942                 if (!job_dependency_new(by, ret, matters, conflicts))
 943                         return -ENOMEM;
 944         } else {
 945                 /* If the job has no parent job, it is the anchor job. */
 946                 assert(!tr->anchor_job);
 947                 tr->anchor_job = ret;
 948         }
 949
 950         if (is_new && !ignore_requirements && type != JOB_NOP) {
 951                 Set *following;
 952
 953                 /* If we are following some other unit, make sure we
 954                  * add all dependencies of everybody following. */
 955                 if (unit_following_set(ret->unit, &following) > 0) {
 956                         SET_FOREACH(dep, following, i) {
 957                                 r = transaction_add_job_and_dependencies(tr, type, dep, ret, false, false, false, ignore_order, e);
 958                                 if (r < 0) {
 959                                         log_unit_full(dep,
 960                                                       r == -ERFKILL ? LOG_INFO : LOG_WARNING,
 961                                                       r, "Cannot add dependency job, ignoring: %s",
 962                                                       bus_error_message(e, r));
 963                                         sd_bus_error_free(e);
 964                                 }
 965                         }
 966
 967                         set_free(following);
 968                 }
 969
 970                 /* Finally, recursively add in all dependencies. */
 971                 if (IN_SET(type, JOB_START, JOB_RESTART)) {
 972                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUIRES], i) {
 973                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, false, false, ignore_order, e);
 974                                 if (r < 0) {
 975                                         if (r != -EBADR) /* job type not applicable */
 976                                                 goto fail;
 977
 978                                         sd_bus_error_free(e);
 979                                 }
 980                         }
 981
 982                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_BINDS_TO], i) {
 983                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, true, false, false, ignore_order, e);
 984                                 if (r < 0) {
 985                                         if (r != -EBADR) /* job type not applicable */
 986                                                 goto fail;
 987
 988                                         sd_bus_error_free(e);
 989                                 }
 990                         }
 991
 992                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_WANTS], i) {
 993                                 r = transaction_add_job_and_dependencies(tr, JOB_START, dep, ret, false, false, false, ignore_order, e);
 994                                 if (r < 0) {
 995                                         /* unit masked, job type not applicable and unit not found are not considered as errors. */
 996                                         log_unit_full(dep,
 997                                                       IN_SET(r, -ERFKILL, -EBADR, -ENOENT) ? LOG_DEBUG : LOG_WARNING,
 998                                                       r, "Cannot add dependency job, ignoring: %s",
 999                                                       bus_error_message(e, r));
1000                                         sd_bus_error_free(e);
1001                                 }
1002                         }
1003
1004                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_REQUISITE], i) {
1005                                 r = transaction_add_job_and_dependencies(tr, JOB_VERIFY_ACTIVE, dep, ret, true, false, false, ignore_order, e);
1006                                 if (r < 0) {
1007                                         if (r != -EBADR) /* job type not applicable */
1008                                                 goto fail;
1009
1010                                         sd_bus_error_free(e);
1011                                 }
1012                         }
1013
1014                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONFLICTS], i) {
1015                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, true, true, false, ignore_order, e);
1016                                 if (r < 0) {
1017                                         if (r != -EBADR) /* job type not applicable */
1018                                                 goto fail;
1019
1020                                         sd_bus_error_free(e);
1021                                 }
1022                         }
1023
1024                         SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONFLICTED_BY], i) {
1025                                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, dep, ret, false, false, false, ignore_order, e);
1026                                 if (r < 0) {
1027                                         log_unit_warning(dep,
1028                                                          "Cannot add dependency job, ignoring: %s",
1029                                                          bus_error_message(e, r));
1030                                         sd_bus_error_free(e);
1031                                 }
1032                         }
1033
1034                 }
1035
1036                 if (IN_SET(type, JOB_STOP, JOB_RESTART)) {
1037                         static const UnitDependency propagate_deps[] = {
1038                                 UNIT_REQUIRED_BY,
1039                                 UNIT_REQUISITE_OF,
1040                                 UNIT_BOUND_BY,
1041                                 UNIT_CONSISTS_OF,
1042                         };
1043
1044                         JobType ptype;
1045                         unsigned j;
1046
1047                         /* We propagate STOP as STOP, but RESTART only
1048                          * as TRY_RESTART, in order not to start
1049                          * dependencies that are not around. */
1050                         ptype = type == JOB_RESTART ? JOB_TRY_RESTART : type;
1051
1052                         for (j = 0; j < ELEMENTSOF(propagate_deps); j++)
1053                                 SET_FOREACH(dep, ret->unit->dependencies[propagate_deps[j]], i) {
1054                                         JobType nt;
1055
1056                                         nt = job_type_collapse(ptype, dep);
1057                                         if (nt == JOB_NOP)
1058                                                 continue;
1059
1060                                         r = transaction_add_job_and_dependencies(tr, nt, dep, ret, true, false, false, ignore_order, e);
1061                                         if (r < 0) {
1062                                                 if (r != -EBADR) /* job type not applicable */
1063                                                         goto fail;
1064
1065                                                 sd_bus_error_free(e);
1066                                         }
1067                                 }
1068                 }
1069
1070                 if (type == JOB_RELOAD)
1071                         transaction_add_propagate_reload_jobs(tr, ret->unit, ret, ignore_order, e);
1072
1073                 /* JOB_VERIFY_STARTED require no dependency handling */
1074         }
1075
1076         return 0;
1077
1078 fail:
1079         return r;
1080 }
1081
1082 int transaction_add_isolate_jobs(Transaction *tr, Manager *m) {
1083         Iterator i;
1084         Unit *u;
1085         char *k;
1086         int r;
1087
1088         assert(tr);
1089         assert(m);
1090
1091         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
1092
1093                 /* ignore aliases */
1094                 if (u->id != k)
1095                         continue;
1096
1097                 if (u->ignore_on_isolate)
1098                         continue;
1099
1100                 /* No need to stop inactive jobs */
1101                 if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(u)) && !u->job)
1102                         continue;
1103
1104                 /* Is there already something listed for this? */
1105                 if (hashmap_get(tr->jobs, u))
1106                         continue;
1107
1108                 r = transaction_add_job_and_dependencies(tr, JOB_STOP, u, tr->anchor_job, true, false, false, false, NULL);
1109                 if (r < 0)
1110                         log_unit_warning_errno(u, r, "Cannot add isolate job, ignoring: %m");
1111         }
1112
1113         return 0;
1114 }
1115
1116 Transaction *transaction_new(bool irreversible) {
1117         Transaction *tr;
1118
1119         tr = new0(Transaction, 1);
1120         if (!tr)
1121                 return NULL;
1122
1123         tr->jobs = hashmap_new(NULL);
1124         if (!tr->jobs)
1125                 return mfree(tr);
1126
1127         tr->irreversible = irreversible;
1128
1129         return tr;
1130 }
1131
1132 void transaction_free(Transaction *tr) {
1133         assert(hashmap_isempty(tr->jobs));
1134         hashmap_free(tr->jobs);
1135         free(tr);
1136 }