manager.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   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 General Public License as published by
  10   the Free Software Foundation; either version 2 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   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <assert.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <sys/epoll.h>
  26 #include <signal.h>
  27 #include <sys/signalfd.h>
  28 #include <sys/wait.h>
  29 #include <unistd.h>
  30 #include <sys/poll.h>
  31
  32 #include "manager.h"
  33 #include "hashmap.h"
  34 #include "macro.h"
  35 #include "strv.h"
  36 #include "log.h"
  37 #include "util.h"
  38 #include "ratelimit.h"
  39
  40 static int manager_setup_signals(Manager *m) {
  41         sigset_t mask;
  42         struct epoll_event ev;
  43
  44         assert(m);
  45
  46         assert_se(reset_all_signal_handlers() == 0);
  47
  48         assert_se(sigemptyset(&mask) == 0);
  49         assert_se(sigaddset(&mask, SIGCHLD) == 0);
  50         assert_se(sigaddset(&mask, SIGINT) == 0);   /* Kernel sends us this on control-alt-del */
  51         assert_se(sigaddset(&mask, SIGWINCH) == 0); /* Kernel sends us this on kbrequest (alt-arrowup) */
  52         assert_se(sigaddset(&mask, SIGTERM) == 0);
  53         assert_se(sigaddset(&mask, SIGHUP) == 0);
  54         assert_se(sigaddset(&mask, SIGUSR1) == 0);
  55         assert_se(sigaddset(&mask, SIGUSR2) == 0);
  56         assert_se(sigaddset(&mask, SIGPIPE) == 0);
  57         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
  58
  59         m->signal_watch.type = WATCH_SIGNAL;
  60         if ((m->signal_watch.fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0)
  61                 return -errno;
  62
  63         zero(ev);
  64         ev.events = EPOLLIN;
  65         ev.data.ptr = &m->signal_watch;
  66
  67         if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->signal_watch.fd, &ev) < 0)
  68                 return -errno;
  69
  70         return 0;
  71 }
  72
  73 Manager* manager_new(void) {
  74         Manager *m;
  75
  76         if (!(m = new0(Manager, 1)))
  77                 return NULL;
  78
  79         m->signal_watch.fd = m->mount_watch.fd = m->udev_watch.fd = m->epoll_fd = -1;
  80         m->current_job_id = 1; /* start as id #1, so that we can leave #0 around as "null-like" value */
  81
  82         if (!(m->units = hashmap_new(string_hash_func, string_compare_func)))
  83                 goto fail;
  84
  85         if (!(m->jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
  86                 goto fail;
  87
  88         if (!(m->transaction_jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
  89                 goto fail;
  90
  91         if (!(m->watch_pids = hashmap_new(trivial_hash_func, trivial_compare_func)))
  92                 goto fail;
  93
  94         if ((m->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0)
  95                 goto fail;
  96
  97         if (manager_setup_signals(m) < 0)
  98                 goto fail;
  99
 100         /* FIXME: this should be called only when the D-Bus bus daemon is running */
 101         if (bus_init(m) < 0)
 102                 goto fail;
 103
 104         return m;
 105
 106 fail:
 107         manager_free(m);
 108         return NULL;
 109 }
 110
 111 void manager_free(Manager *m) {
 112         UnitType c;
 113         Unit *u;
 114         Job *j;
 115
 116         assert(m);
 117
 118         while ((j = hashmap_first(m->transaction_jobs)))
 119                 job_free(j);
 120
 121         while ((u = hashmap_first(m->units)))
 122                 unit_free(u);
 123
 124         for (c = 0; c < _UNIT_TYPE_MAX; c++)
 125                 if (unit_vtable[c]->shutdown)
 126                         unit_vtable[c]->shutdown(m);
 127
 128         bus_done(m);
 129
 130         hashmap_free(m->units);
 131         hashmap_free(m->jobs);
 132         hashmap_free(m->transaction_jobs);
 133         hashmap_free(m->watch_pids);
 134
 135         if (m->epoll_fd >= 0)
 136                 close_nointr(m->epoll_fd);
 137         if (m->signal_watch.fd >= 0)
 138                 close_nointr(m->signal_watch.fd);
 139
 140         free(m);
 141 }
 142
 143 int manager_coldplug(Manager *m) {
 144         int r;
 145         UnitType c;
 146         Iterator i;
 147         Unit *u;
 148         char *k;
 149
 150         assert(m);
 151
 152         /* First, let's ask every type to load all units from
 153          * disk/kernel that it might know */
 154         for (c = 0; c < _UNIT_TYPE_MAX; c++)
 155                 if (unit_vtable[c]->enumerate)
 156                         if ((r = unit_vtable[c]->enumerate(m)) < 0)
 157                                 return r;
 158
 159         manager_dispatch_load_queue(m);
 160
 161         /* Then, let's set up their initial state. */
 162         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
 163
 164                 /* ignore aliases */
 165                 if (unit_id(u) != k)
 166                         continue;
 167
 168                 if (UNIT_VTABLE(u)->coldplug)
 169                         if ((r = UNIT_VTABLE(u)->coldplug(u)) < 0)
 170                                 return r;
 171         }
 172
 173         return 0;
 174 }
 175
 176 static void transaction_delete_job(Manager *m, Job *j) {
 177         assert(m);
 178         assert(j);
 179
 180         /* Deletes one job from the transaction */
 181
 182         manager_transaction_unlink_job(m, j);
 183
 184         if (!j->installed)
 185                 job_free(j);
 186 }
 187
 188 static void transaction_delete_unit(Manager *m, Unit *u) {
 189         Job *j;
 190
 191         /* Deletes all jobs associated with a certain unit from the
 192          * transaction */
 193
 194         while ((j = hashmap_get(m->transaction_jobs, u)))
 195                 transaction_delete_job(m, j);
 196 }
 197
 198 static void transaction_clean_dependencies(Manager *m) {
 199         Iterator i;
 200         Job *j;
 201
 202         assert(m);
 203
 204         /* Drops all dependencies of all installed jobs */
 205
 206         HASHMAP_FOREACH(j, m->jobs, i) {
 207                 while (j->subject_list)
 208                         job_dependency_free(j->subject_list);
 209                 while (j->object_list)
 210                         job_dependency_free(j->object_list);
 211         }
 212
 213         assert(!m->transaction_anchor);
 214 }
 215
 216 static void transaction_abort(Manager *m) {
 217         Job *j;
 218
 219         assert(m);
 220
 221         while ((j = hashmap_first(m->transaction_jobs)))
 222                 if (j->installed)
 223                         transaction_delete_job(m, j);
 224                 else
 225                         job_free(j);
 226
 227         assert(hashmap_isempty(m->transaction_jobs));
 228
 229         transaction_clean_dependencies(m);
 230 }
 231
 232 static void transaction_find_jobs_that_matter_to_anchor(Manager *m, Job *j, unsigned generation) {
 233         JobDependency *l;
 234
 235         assert(m);
 236
 237         /* A recursive sweep through the graph that marks all units
 238          * that matter to the anchor job, i.e. are directly or
 239          * indirectly a dependency of the anchor job via paths that
 240          * are fully marked as mattering. */
 241
 242         if (j)
 243                 l = j->subject_list;
 244         else
 245                 l = m->transaction_anchor;
 246
 247         LIST_FOREACH(subject, l, l) {
 248
 249                 /* This link does not matter */
 250                 if (!l->matters)
 251                         continue;
 252
 253                 /* This unit has already been marked */
 254                 if (l->object->generation == generation)
 255                         continue;
 256
 257                 l->object->matters_to_anchor = true;
 258                 l->object->generation = generation;
 259
 260                 transaction_find_jobs_that_matter_to_anchor(m, l->object, generation);
 261         }
 262 }
 263
 264 static void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, JobType t) {
 265         JobDependency *l, *last;
 266
 267         assert(j);
 268         assert(other);
 269         assert(j->unit == other->unit);
 270         assert(!j->installed);
 271
 272         /* Merges 'other' into 'j' and then deletes j. */
 273
 274         j->type = t;
 275         j->state = JOB_WAITING;
 276         j->forced = j->forced || other->forced;
 277
 278         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
 279
 280         /* Patch us in as new owner of the JobDependency objects */
 281         last = NULL;
 282         LIST_FOREACH(subject, l, other->subject_list) {
 283                 assert(l->subject == other);
 284                 l->subject = j;
 285                 last = l;
 286         }
 287
 288         /* Merge both lists */
 289         if (last) {
 290                 last->subject_next = j->subject_list;
 291                 if (j->subject_list)
 292                         j->subject_list->subject_prev = last;
 293                 j->subject_list = other->subject_list;
 294         }
 295
 296         /* Patch us in as new owner of the JobDependency objects */
 297         last = NULL;
 298         LIST_FOREACH(object, l, other->object_list) {
 299                 assert(l->object == other);
 300                 l->object = j;
 301                 last = l;
 302         }
 303
 304         /* Merge both lists */
 305         if (last) {
 306                 last->object_next = j->object_list;
 307                 if (j->object_list)
 308                         j->object_list->object_prev = last;
 309                 j->object_list = other->object_list;
 310         }
 311
 312         /* Kill the other job */
 313         other->subject_list = NULL;
 314         other->object_list = NULL;
 315         transaction_delete_job(m, other);
 316 }
 317
 318 static int delete_one_unmergeable_job(Manager *m, Job *j) {
 319         Job *k;
 320
 321         assert(j);
 322
 323         /* Tries to delete one item in the linked list
 324          * j->transaction_next->transaction_next->... that conflicts
 325          * whith another one, in an attempt to make an inconsistent
 326          * transaction work. */
 327
 328         /* We rely here on the fact that if a merged with b does not
 329          * merge with c, either a or b merge with c neither */
 330         LIST_FOREACH(transaction, j, j)
 331                 LIST_FOREACH(transaction, k, j->transaction_next) {
 332                         Job *d;
 333
 334                         /* Is this one mergeable? Then skip it */
 335                         if (job_type_is_mergeable(j->type, k->type))
 336                                 continue;
 337
 338                         /* Ok, we found two that conflict, let's see if we can
 339                          * drop one of them */
 340                         if (!j->matters_to_anchor)
 341                                 d = j;
 342                         else if (!k->matters_to_anchor)
 343                                 d = k;
 344                         else
 345                                 return -ENOEXEC;
 346
 347                         /* Ok, we can drop one, so let's do so. */
 348                         log_debug("Try to fix job merging by deleting job %s/%s", unit_id(d->unit), job_type_to_string(d->type));
 349                         transaction_delete_job(m, d);
 350                         return 0;
 351                 }
 352
 353         return -EINVAL;
 354 }
 355
 356 static int transaction_merge_jobs(Manager *m) {
 357         Job *j;
 358         Iterator i;
 359         int r;
 360
 361         assert(m);
 362
 363         /* First step, check whether any of the jobs for one specific
 364          * task conflict. If so, try to drop one of them. */
 365         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 366                 JobType t;
 367                 Job *k;
 368
 369                 t = j->type;
 370                 LIST_FOREACH(transaction, k, j->transaction_next) {
 371                         if ((r = job_type_merge(&t, k->type)) >= 0)
 372                                 continue;
 373
 374                         /* OK, we could not merge all jobs for this
 375                          * action. Let's see if we can get rid of one
 376                          * of them */
 377
 378                         if ((r = delete_one_unmergeable_job(m, j)) >= 0)
 379                                 /* Ok, we managed to drop one, now
 380                                  * let's ask our callers to call us
 381                                  * again after garbage collecting */
 382                                 return -EAGAIN;
 383
 384                         /* We couldn't merge anything. Failure */
 385                         return r;
 386                 }
 387         }
 388
 389         /* Second step, merge the jobs. */
 390         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 391                 JobType t = j->type;
 392                 Job *k;
 393
 394                 /* Merge all transactions */
 395                 LIST_FOREACH(transaction, k, j->transaction_next)
 396                         assert_se(job_type_merge(&t, k->type) == 0);
 397
 398                 /* If an active job is mergeable, merge it too */
 399                 if (j->unit->meta.job)
 400                         job_type_merge(&t, j->unit->meta.job->type); /* Might fail. Which is OK */
 401
 402                 while ((k = j->transaction_next)) {
 403                         if (j->installed) {
 404                                 transaction_merge_and_delete_job(m, k, j, t);
 405                                 j = k;
 406                         } else
 407                                 transaction_merge_and_delete_job(m, j, k, t);
 408                 }
 409
 410                 assert(!j->transaction_next);
 411                 assert(!j->transaction_prev);
 412         }
 413
 414         return 0;
 415 }
 416
 417 static bool unit_matters_to_anchor(Unit *u, Job *j) {
 418         assert(u);
 419         assert(!j->transaction_prev);
 420
 421         /* Checks whether at least one of the jobs for this unit
 422          * matters to the anchor. */
 423
 424         LIST_FOREACH(transaction, j, j)
 425                 if (j->matters_to_anchor)
 426                         return true;
 427
 428         return false;
 429 }
 430
 431 static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
 432         Iterator i;
 433         Unit *u;
 434         int r;
 435
 436         assert(m);
 437         assert(j);
 438         assert(!j->transaction_prev);
 439
 440         /* Does a recursive sweep through the ordering graph, looking
 441          * for a cycle. If we find cycle we try to break it. */
 442
 443         /* Did we find a cycle? */
 444         if (j->marker && j->generation == generation) {
 445                 Job *k;
 446
 447                 /* So, we already have been here. We have a
 448                  * cycle. Let's try to break it. We go backwards in
 449                  * our path and try to find a suitable job to
 450                  * remove. We use the marker to find our way back,
 451                  * since smart how we are we stored our way back in
 452                  * there. */
 453
 454                 log_debug("Found cycle on %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 455
 456                 for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
 457
 458                         log_debug("Walked on cycle path to %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 459
 460                         if (!k->installed &&
 461                             !unit_matters_to_anchor(k->unit, k)) {
 462                                 /* Ok, we can drop this one, so let's
 463                                  * do so. */
 464                                 log_debug("Breaking order cycle by deleting job %s/%s", unit_id(k->unit), job_type_to_string(k->type));
 465                                 transaction_delete_unit(m, k->unit);
 466                                 return -EAGAIN;
 467                         }
 468
 469                         /* Check if this in fact was the beginning of
 470                          * the cycle */
 471                         if (k == j)
 472                                 break;
 473                 }
 474
 475                 log_debug("Unable to break cycle");
 476
 477                 return -ENOEXEC;
 478         }
 479
 480         /* Make the marker point to where we come from, so that we can
 481          * find our way backwards if we want to break a cycle */
 482         j->marker = from;
 483         j->generation = generation;
 484
 485         /* We assume that the the dependencies are bidirectional, and
 486          * hence can ignore UNIT_AFTER */
 487         SET_FOREACH(u, j->unit->meta.dependencies[UNIT_BEFORE], i) {
 488                 Job *o;
 489
 490                 /* Is there a job for this unit? */
 491                 if (!(o = hashmap_get(m->transaction_jobs, u)))
 492
 493                         /* Ok, there is no job for this in the
 494                          * transaction, but maybe there is already one
 495                          * running? */
 496                         if (!(o = u->meta.job))
 497                                 continue;
 498
 499                 if ((r = transaction_verify_order_one(m, o, j, generation)) < 0)
 500                         return r;
 501         }
 502
 503         /* Ok, let's backtrack, and remember that this entry is not on
 504          * our path anymore. */
 505         j->marker = NULL;
 506
 507         return 0;
 508 }
 509
 510 static int transaction_verify_order(Manager *m, unsigned *generation) {
 511         Job *j;
 512         int r;
 513         Iterator i;
 514
 515         assert(m);
 516         assert(generation);
 517
 518         /* Check if the ordering graph is cyclic. If it is, try to fix
 519          * that up by dropping one of the jobs. */
 520
 521         HASHMAP_FOREACH(j, m->transaction_jobs, i)
 522                 if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
 523                         return r;
 524
 525         return 0;
 526 }
 527
 528 static void transaction_collect_garbage(Manager *m) {
 529         bool again;
 530
 531         assert(m);
 532
 533         /* Drop jobs that are not required by any other job */
 534
 535         do {
 536                 Iterator i;
 537                 Job *j;
 538
 539                 again = false;
 540
 541                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 542                         if (j->object_list)
 543                                 continue;
 544
 545                         log_debug("Garbage collecting job %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 546                         transaction_delete_job(m, j);
 547                         again = true;
 548                         break;
 549                 }
 550
 551         } while (again);
 552 }
 553
 554 static int transaction_is_destructive(Manager *m, JobMode mode) {
 555         Iterator i;
 556         Job *j;
 557
 558         assert(m);
 559
 560         /* Checks whether applying this transaction means that
 561          * existing jobs would be replaced */
 562
 563         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 564
 565                 /* Assume merged */
 566                 assert(!j->transaction_prev);
 567                 assert(!j->transaction_next);
 568
 569                 if (j->unit->meta.job &&
 570                     j->unit->meta.job != j &&
 571                     !job_type_is_superset(j->type, j->unit->meta.job->type))
 572                         return -EEXIST;
 573         }
 574
 575         return 0;
 576 }
 577
 578 static void transaction_minimize_impact(Manager *m) {
 579         bool again;
 580         assert(m);
 581
 582         /* Drops all unnecessary jobs that reverse already active jobs
 583          * or that stop a running service. */
 584
 585         do {
 586                 Job *j;
 587                 Iterator i;
 588
 589                 again = false;
 590
 591                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 592                         LIST_FOREACH(transaction, j, j) {
 593                                 bool stops_running_service, changes_existing_job;
 594
 595                                 /* If it matters, we shouldn't drop it */
 596                                 if (j->matters_to_anchor)
 597                                         continue;
 598
 599                                 /* Would this stop a running service?
 600                                  * Would this change an existing job?
 601                                  * If so, let's drop this entry */
 602
 603                                 stops_running_service =
 604                                         j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 605
 606                                 changes_existing_job =
 607                                         j->unit->meta.job && job_type_is_conflicting(j->type, j->unit->meta.job->state);
 608
 609                                 if (!stops_running_service && !changes_existing_job)
 610                                         continue;
 611
 612                                 if (stops_running_service)
 613                                         log_debug("%s/%s would stop a running service.", unit_id(j->unit), job_type_to_string(j->type));
 614
 615                                 if (changes_existing_job)
 616                                         log_debug("%s/%s would change existing job.", unit_id(j->unit), job_type_to_string(j->type));
 617
 618                                 /* Ok, let's get rid of this */
 619                                 log_debug("Deleting %s/%s to minimize impact.", unit_id(j->unit), job_type_to_string(j->type));
 620
 621                                 transaction_delete_job(m, j);
 622                                 again = true;
 623                                 break;
 624                         }
 625
 626                         if (again)
 627                                 break;
 628                 }
 629
 630         } while (again);
 631 }
 632
 633 static int transaction_apply(Manager *m, JobMode mode) {
 634         Iterator i;
 635         Job *j;
 636         int r;
 637
 638         /* Moves the transaction jobs to the set of active jobs */
 639
 640         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 641                 /* Assume merged */
 642                 assert(!j->transaction_prev);
 643                 assert(!j->transaction_next);
 644
 645                 if (j->installed)
 646                         continue;
 647
 648                 if ((r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j)) < 0)
 649                         goto rollback;
 650         }
 651
 652         while ((j = hashmap_steal_first(m->transaction_jobs))) {
 653                 if (j->installed)
 654                         continue;
 655
 656                 if (j->unit->meta.job)
 657                         job_free(j->unit->meta.job);
 658
 659                 j->unit->meta.job = j;
 660                 j->installed = true;
 661
 662                 /* We're fully installed. Now let's free data we don't
 663                  * need anymore. */
 664
 665                 assert(!j->transaction_next);
 666                 assert(!j->transaction_prev);
 667
 668                 job_schedule_run(j);
 669         }
 670
 671         /* As last step, kill all remaining job dependencies. */
 672         transaction_clean_dependencies(m);
 673
 674         return 0;
 675
 676 rollback:
 677
 678         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 679                 if (j->installed)
 680                         continue;
 681
 682                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 683         }
 684
 685         return r;
 686 }
 687
 688 static int transaction_activate(Manager *m, JobMode mode) {
 689         int r;
 690         unsigned generation = 1;
 691
 692         assert(m);
 693
 694         /* This applies the changes recorded in transaction_jobs to
 695          * the actual list of jobs, if possible. */
 696
 697         /* First step: figure out which jobs matter */
 698         transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
 699
 700         /* Second step: Try not to stop any running services if
 701          * we don't have to. Don't try to reverse running
 702          * jobs if we don't have to. */
 703         transaction_minimize_impact(m);
 704
 705         for (;;) {
 706                 /* Third step: Let's remove unneeded jobs that might
 707                  * be lurking. */
 708                 transaction_collect_garbage(m);
 709
 710                 /* Fourth step: verify order makes sense and correct
 711                  * cycles if necessary and possible */
 712                 if ((r = transaction_verify_order(m, &generation)) >= 0)
 713                         break;
 714
 715                 if (r != -EAGAIN) {
 716                         log_debug("Requested transaction contains an unfixable cyclic ordering dependency: %s", strerror(-r));
 717                         goto rollback;
 718                 }
 719
 720                 /* Let's see if the resulting transaction ordering
 721                  * graph is still cyclic... */
 722         }
 723
 724         for (;;) {
 725                 /* Fifth step: let's drop unmergeable entries if
 726                  * necessary and possible, merge entries we can
 727                  * merge */
 728                 if ((r = transaction_merge_jobs(m)) >= 0)
 729                         break;
 730
 731                 if (r != -EAGAIN) {
 732                         log_debug("Requested transaction contains unmergable jobs: %s", strerror(-r));
 733                         goto rollback;
 734                 }
 735
 736                 /* Sixth step: an entry got dropped, let's garbage
 737                  * collect its dependencies. */
 738                 transaction_collect_garbage(m);
 739
 740                 /* Let's see if the resulting transaction still has
 741                  * unmergeable entries ... */
 742         }
 743
 744         /* Seventh step: check whether we can actually apply this */
 745         if (mode == JOB_FAIL)
 746                 if ((r = transaction_is_destructive(m, mode)) < 0) {
 747                         log_debug("Requested transaction contradicts existing jobs: %s", strerror(-r));
 748                         goto rollback;
 749                 }
 750
 751         /* Eights step: apply changes */
 752         if ((r = transaction_apply(m, mode)) < 0) {
 753                 log_debug("Failed to apply transaction: %s", strerror(-r));
 754                 goto rollback;
 755         }
 756
 757         assert(hashmap_isempty(m->transaction_jobs));
 758         assert(!m->transaction_anchor);
 759
 760         return 0;
 761
 762 rollback:
 763         transaction_abort(m);
 764         return r;
 765 }
 766
 767 static Job* transaction_add_one_job(Manager *m, JobType type, Unit *unit, bool force, bool *is_new) {
 768         Job *j, *f;
 769         int r;
 770
 771         assert(m);
 772         assert(unit);
 773
 774         /* Looks for an axisting prospective job and returns that. If
 775          * it doesn't exist it is created and added to the prospective
 776          * jobs list. */
 777
 778         f = hashmap_get(m->transaction_jobs, unit);
 779
 780         LIST_FOREACH(transaction, j, f) {
 781                 assert(j->unit == unit);
 782
 783                 if (j->type == type) {
 784                         if (is_new)
 785                                 *is_new = false;
 786                         return j;
 787                 }
 788         }
 789
 790         if (unit->meta.job && unit->meta.job->type == type)
 791                 j = unit->meta.job;
 792         else if (!(j = job_new(m, type, unit)))
 793                 return NULL;
 794
 795         j->generation = 0;
 796         j->marker = NULL;
 797         j->matters_to_anchor = false;
 798         j->forced = force;
 799
 800         LIST_PREPEND(Job, transaction, f, j);
 801
 802         if ((r = hashmap_replace(m->transaction_jobs, unit, f)) < 0) {
 803                 job_free(j);
 804                 return NULL;
 805         }
 806
 807         if (is_new)
 808                 *is_new = true;
 809
 810         return j;
 811 }
 812
 813 void manager_transaction_unlink_job(Manager *m, Job *j) {
 814         assert(m);
 815         assert(j);
 816
 817         if (j->transaction_prev)
 818                 j->transaction_prev->transaction_next = j->transaction_next;
 819         else if (j->transaction_next)
 820                 hashmap_replace(m->transaction_jobs, j->unit, j->transaction_next);
 821         else
 822                 hashmap_remove_value(m->transaction_jobs, j->unit, j);
 823
 824         if (j->transaction_next)
 825                 j->transaction_next->transaction_prev = j->transaction_prev;
 826
 827         j->transaction_prev = j->transaction_next = NULL;
 828
 829         while (j->subject_list)
 830                 job_dependency_free(j->subject_list);
 831
 832         while (j->object_list) {
 833                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 834
 835                 job_dependency_free(j->object_list);
 836
 837                 if (other) {
 838                         log_debug("Deleting job %s/%s as dependency of job %s/%s",
 839                                   unit_id(other->unit), job_type_to_string(other->type),
 840                                   unit_id(j->unit), job_type_to_string(j->type));
 841                         transaction_delete_job(m, other);
 842                 }
 843         }
 844 }
 845
 846 static int transaction_add_job_and_dependencies(Manager *m, JobType type, Unit *unit, Job *by, bool matters, bool force, Job **_ret) {
 847         Job *ret;
 848         Iterator i;
 849         Unit *dep;
 850         int r;
 851         bool is_new;
 852
 853         assert(m);
 854         assert(type < _JOB_TYPE_MAX);
 855         assert(unit);
 856
 857         if (unit->meta.load_state != UNIT_LOADED)
 858                 return -EINVAL;
 859
 860         if (!unit_job_is_applicable(unit, type))
 861                 return -EBADR;
 862
 863         /* First add the job. */
 864         if (!(ret = transaction_add_one_job(m, type, unit, force, &is_new)))
 865                 return -ENOMEM;
 866
 867         /* Then, add a link to the job. */
 868         if (!job_dependency_new(by, ret, matters))
 869                 return -ENOMEM;
 870
 871         if (is_new) {
 872                 /* Finally, recursively add in all dependencies. */
 873                 if (type == JOB_START || type == JOB_RELOAD_OR_START) {
 874                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRES], i)
 875                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 876                                         goto fail;
 877                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUIRES], i)
 878                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
 879                                         goto fail;
 880                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_WANTS], i)
 881                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, force, NULL)) < 0 && r != -EBADR)
 882                                         goto fail;
 883                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUISITE], i)
 884                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 885                                         goto fail;
 886                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUISITE], i)
 887                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
 888                                         goto fail;
 889                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_CONFLICTS], i)
 890                                 if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 891                                         goto fail;
 892
 893                 } else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
 894
 895                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRED_BY], i)
 896                                 if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 897                                         goto fail;
 898                 }
 899
 900                 /* JOB_VERIFY_STARTED, JOB_RELOAD require no dependency handling */
 901         }
 902
 903         return 0;
 904
 905 fail:
 906         return r;
 907 }
 908
 909 int manager_add_job(Manager *m, JobType type, Unit *unit, JobMode mode, bool force, Job **_ret) {
 910         int r;
 911         Job *ret;
 912
 913         assert(m);
 914         assert(type < _JOB_TYPE_MAX);
 915         assert(unit);
 916         assert(mode < _JOB_MODE_MAX);
 917
 918         log_debug("Trying to enqueue job %s/%s", unit_id(unit), job_type_to_string(type));
 919
 920         if ((r = transaction_add_job_and_dependencies(m, type, unit, NULL, true, force, &ret))) {
 921                 transaction_abort(m);
 922                 return r;
 923         }
 924
 925         if ((r = transaction_activate(m, mode)) < 0)
 926                 return r;
 927
 928         log_debug("Enqueued job %s/%s", unit_id(unit), job_type_to_string(type));
 929
 930         if (_ret)
 931                 *_ret = ret;
 932
 933         return 0;
 934 }
 935
 936 Job *manager_get_job(Manager *m, uint32_t id) {
 937         assert(m);
 938
 939         return hashmap_get(m->jobs, UINT32_TO_PTR(id));
 940 }
 941
 942 Unit *manager_get_unit(Manager *m, const char *name) {
 943         assert(m);
 944         assert(name);
 945
 946         return hashmap_get(m->units, name);
 947 }
 948
 949 void manager_dispatch_load_queue(Manager *m) {
 950         Meta *meta;
 951
 952         assert(m);
 953
 954         /* Make sure we are not run recursively */
 955         if (m->dispatching_load_queue)
 956                 return;
 957
 958         m->dispatching_load_queue = true;
 959
 960         /* Dispatches the load queue. Takes a unit from the queue and
 961          * tries to load its data until the queue is empty */
 962
 963         while ((meta = m->load_queue)) {
 964                 assert(meta->in_load_queue);
 965
 966                 unit_load(UNIT(meta));
 967         }
 968
 969         m->dispatching_load_queue = false;
 970 }
 971
 972 int manager_load_unit(Manager *m, const char *path, Unit **_ret) {
 973         Unit *ret;
 974         int r;
 975         const char *name;
 976
 977         assert(m);
 978         assert(path);
 979         assert(_ret);
 980
 981         /* This will load the service information files, but not actually
 982          * start any services or anything. */
 983
 984         name = file_name_from_path(path);
 985
 986         if ((ret = manager_get_unit(m, name))) {
 987                 *_ret = ret;
 988                 return 0;
 989         }
 990
 991         if (!(ret = unit_new(m)))
 992                 return -ENOMEM;
 993
 994         if (is_path(path)) {
 995                 if (!(ret->meta.load_path = strdup(path))) {
 996                         unit_free(ret);
 997                         return -ENOMEM;
 998                 }
 999         }
1000
1001         if ((r = unit_add_name(ret, name)) < 0) {
1002                 unit_free(ret);
1003                 return r;
1004         }
1005
1006         unit_add_to_load_queue(ret);
1007         manager_dispatch_load_queue(m);
1008
1009         *_ret = ret;
1010         return 0;
1011 }
1012
1013 void manager_dump_jobs(Manager *s, FILE *f, const char *prefix) {
1014         Iterator i;
1015         Job *j;
1016
1017         assert(s);
1018         assert(f);
1019
1020         HASHMAP_FOREACH(j, s->jobs, i)
1021                 job_dump(j, f, prefix);
1022 }
1023
1024 void manager_dump_units(Manager *s, FILE *f, const char *prefix) {
1025         Iterator i;
1026         Unit *u;
1027         const char *t;
1028
1029         assert(s);
1030         assert(f);
1031
1032         HASHMAP_FOREACH_KEY(u, t, s->units, i)
1033                 if (unit_id(u) == t)
1034                         unit_dump(u, f, prefix);
1035 }
1036
1037 void manager_clear_jobs(Manager *m) {
1038         Job *j;
1039
1040         assert(m);
1041
1042         transaction_abort(m);
1043
1044         while ((j = hashmap_first(m->jobs)))
1045                 job_free(j);
1046 }
1047
1048 void manager_dispatch_run_queue(Manager *m) {
1049         Job *j;
1050
1051         if (m->dispatching_run_queue)
1052                 return;
1053
1054         m->dispatching_run_queue = true;
1055
1056         while ((j = m->run_queue)) {
1057                 assert(j->installed);
1058                 assert(j->in_run_queue);
1059
1060                 job_run_and_invalidate(j);
1061         }
1062
1063         m->dispatching_run_queue = false;
1064 }
1065
1066 static int manager_dispatch_sigchld(Manager *m) {
1067         assert(m);
1068
1069         log_debug("dispatching SIGCHLD");
1070
1071         for (;;) {
1072                 siginfo_t si;
1073                 Unit *u;
1074
1075                 zero(si);
1076                 if (waitid(P_ALL, 0, &si, WEXITED|WNOHANG) < 0) {
1077
1078                         if (errno == ECHILD)
1079                                 break;
1080
1081                         return -errno;
1082                 }
1083
1084                 if (si.si_pid == 0)
1085                         break;
1086
1087                 if (si.si_code != CLD_EXITED && si.si_code != CLD_KILLED && si.si_code != CLD_DUMPED)
1088                         continue;
1089
1090                 log_debug("child %llu died (code=%s, status=%i)", (long long unsigned) si.si_pid, sigchld_code_to_string(si.si_code), si.si_status);
1091
1092                 if (!(u = hashmap_remove(m->watch_pids, UINT32_TO_PTR(si.si_pid))))
1093                         continue;
1094
1095                 UNIT_VTABLE(u)->sigchld_event(u, si.si_pid, si.si_code, si.si_status);
1096         }
1097
1098         return 0;
1099 }
1100
1101 static int manager_process_signal_fd(Manager *m, bool *quit) {
1102         ssize_t n;
1103         struct signalfd_siginfo sfsi;
1104         bool sigchld = false;
1105
1106         assert(m);
1107
1108         for (;;) {
1109                 if ((n = read(m->signal_watch.fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
1110
1111                         if (n >= 0)
1112                                 return -EIO;
1113
1114                         if (errno == EAGAIN)
1115                                 break;
1116
1117                         return -errno;
1118                 }
1119
1120                 switch (sfsi.ssi_signo) {
1121
1122                 case SIGCHLD:
1123                         sigchld = true;
1124                         break;
1125
1126                 case SIGINT:
1127                 case SIGTERM:
1128                         *quit = true;
1129                         return 0;
1130
1131                 default:
1132                         log_info("Got unhandled signal <%s>.", strsignal(sfsi.ssi_signo));
1133                 }
1134         }
1135
1136         if (sigchld)
1137                 return manager_dispatch_sigchld(m);
1138
1139         return 0;
1140 }
1141
1142 static int process_event(Manager *m, struct epoll_event *ev, bool *quit) {
1143         int r;
1144         Watch *w;
1145
1146         assert(m);
1147         assert(ev);
1148
1149         assert(w = ev->data.ptr);
1150
1151         switch (w->type) {
1152
1153         case WATCH_SIGNAL:
1154
1155                 /* An incoming signal? */
1156                 if (ev->events != EPOLLIN)
1157                         return -EINVAL;
1158
1159                 if ((r = manager_process_signal_fd(m, quit)) < 0)
1160                         return r;
1161
1162                 break;
1163
1164         case WATCH_FD:
1165
1166                 /* Some fd event, to be dispatched to the units */
1167                 UNIT_VTABLE(w->data.unit)->fd_event(w->data.unit, w->fd, ev->events, w);
1168                 break;
1169
1170         case WATCH_TIMER: {
1171                 uint64_t v;
1172                 ssize_t k;
1173
1174                 /* Some timer event, to be dispatched to the units */
1175                 if ((k = read(ev->data.fd, &v, sizeof(v))) != sizeof(v)) {
1176
1177                         if (k < 0 && (errno == EINTR || errno == EAGAIN))
1178                                 break;
1179
1180                         return k < 0 ? -errno : -EIO;
1181                 }
1182
1183                 UNIT_VTABLE(w->data.unit)->timer_event(w->data.unit, v, w);
1184                 break;
1185         }
1186
1187         case WATCH_MOUNT:
1188                 /* Some mount table change, intended for the mount subsystem */
1189                 mount_fd_event(m, ev->events);
1190                 break;
1191
1192         case WATCH_UDEV:
1193                 /* Some notification from udev, intended for the device subsystem */
1194                 device_fd_event(m, ev->events);
1195                 break;
1196
1197         case WATCH_DBUS_WATCH:
1198                 bus_watch_event(m, w, ev->events);
1199                 break;
1200
1201         case WATCH_DBUS_TIMEOUT:
1202                 bus_timeout_event(m, w, ev->events);
1203                 break;
1204
1205         default:
1206                 assert_not_reached("Unknown epoll event type.");
1207         }
1208
1209         return 0;
1210 }
1211
1212 int manager_loop(Manager *m) {
1213         int r;
1214         bool quit = false;
1215
1216         RATELIMIT_DEFINE(rl, 1*USEC_PER_SEC, 1000);
1217
1218         assert(m);
1219
1220         for (;;) {
1221                 struct epoll_event event;
1222                 int n;
1223
1224                 if (!ratelimit_test(&rl)) {
1225                         /* Yay, something is going seriously wrong, pause a little */
1226                         log_warning("Looping too fast. Throttling execution a little.");
1227                         sleep(1);
1228                 }
1229
1230                 manager_dispatch_run_queue(m);
1231
1232                 if (m->request_bus_dispatch) {
1233                         bus_dispatch(m);
1234                         continue;
1235                 }
1236
1237                 if ((n = epoll_wait(m->epoll_fd, &event, 1, -1)) < 0) {
1238
1239                         if (errno == -EINTR)
1240                                 continue;
1241
1242                         return -errno;
1243                 }
1244
1245                 assert(n == 1);
1246
1247                 if ((r = process_event(m, &event, &quit)) < 0)
1248                         return r;
1249
1250                 if (quit)
1251                         return 0;
1252         }
1253 }
1254
1255 int manager_get_unit_from_dbus_path(Manager *m, const char *s, Unit **_u) {
1256         char *n;
1257         Unit *u;
1258
1259         assert(m);
1260         assert(s);
1261         assert(_u);
1262
1263         if (!startswith(s, "/org/freedesktop/systemd1/unit/"))
1264                 return -EINVAL;
1265
1266         if (!(n = bus_path_unescape(s+31)))
1267                 return -ENOMEM;
1268
1269         u = manager_get_unit(m, n);
1270         free(n);
1271
1272         if (!u)
1273                 return -ENOENT;
1274
1275         *_u = u;
1276
1277         return 0;
1278 }
1279
1280 int manager_get_job_from_dbus_path(Manager *m, const char *s, Job **_j) {
1281         Job *j;
1282         unsigned id;
1283         int r;
1284
1285         assert(m);
1286         assert(s);
1287         assert(_j);
1288
1289         if (!startswith(s, "/org/freedesktop/systemd1/job/"))
1290                 return -EINVAL;
1291
1292         if ((r = safe_atou(s + 30, &id)) < 0)
1293                 return r;
1294
1295         if (!(j = manager_get_job(m, id)))
1296                 return -ENOENT;
1297
1298         *_j = j;
1299
1300         return 0;
1301 }