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 #include <sys/reboot.h>
  32 #include <sys/ioctl.h>
  33 #include <linux/kd.h>
  34 #include <libcgroup.h>
  35
  36 #include "manager.h"
  37 #include "hashmap.h"
  38 #include "macro.h"
  39 #include "strv.h"
  40 #include "log.h"
  41 #include "util.h"
  42 #include "ratelimit.h"
  43 #include "cgroup.h"
  44 #include "mount-setup.h"
  45
  46 static int manager_setup_signals(Manager *m) {
  47         sigset_t mask;
  48         struct epoll_event ev;
  49
  50         assert(m);
  51
  52         assert_se(sigemptyset(&mask) == 0);
  53         assert_se(sigaddset(&mask, SIGCHLD) == 0);
  54         assert_se(sigaddset(&mask, SIGINT) == 0);   /* Kernel sends us this on control-alt-del */
  55         assert_se(sigaddset(&mask, SIGWINCH) == 0); /* Kernel sends us this on kbrequest (alt-arrowup) */
  56         assert_se(sigaddset(&mask, SIGTERM) == 0);
  57         assert_se(sigaddset(&mask, SIGHUP) == 0);
  58         assert_se(sigaddset(&mask, SIGUSR1) == 0);
  59         assert_se(sigaddset(&mask, SIGUSR2) == 0);
  60         assert_se(sigaddset(&mask, SIGPIPE) == 0);
  61         assert_se(sigaddset(&mask, SIGPWR) == 0);
  62         assert_se(sigaddset(&mask, SIGTTIN) == 0);
  63         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
  64
  65         m->signal_watch.type = WATCH_SIGNAL;
  66         if ((m->signal_watch.fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0)
  67                 return -errno;
  68
  69         zero(ev);
  70         ev.events = EPOLLIN;
  71         ev.data.ptr = &m->signal_watch;
  72
  73         if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->signal_watch.fd, &ev) < 0)
  74                 return -errno;
  75
  76         if (m->running_as == MANAGER_INIT) {
  77                 /* Enable that we get SIGINT on control-alt-del */
  78                 if (reboot(RB_DISABLE_CAD) < 0)
  79                         log_warning("Failed to enable ctrl-alt-del handling: %s", strerror(errno));
  80
  81                 /* Enable that we get SIGWINCH on kbrequest */
  82                 if (ioctl(0, KDSIGACCEPT, SIGWINCH) < 0)
  83                         log_warning("Failed to enable kbrequest handling: %s", strerror(errno));
  84         }
  85
  86         return 0;
  87 }
  88
  89 static char** session_dirs(void) {
  90         const char *home, *e;
  91         char *config_home = NULL, *data_home = NULL;
  92         char **config_dirs = NULL, **data_dirs = NULL;
  93         char **r = NULL, **t;
  94
  95         /* Implement the mechanisms defined in
  96          *
  97          * http://standards.freedesktop.org/basedir-spec/basedir-spec-0.6.html
  98          *
  99          * We look in both the config and the data dirs because we
 100          * want to encourage that distributors ship their unit files
 101          * as data, and allow overriding as configuration.
 102          */
 103
 104         home = getenv("HOME");
 105
 106         if ((e = getenv("XDG_CONFIG_HOME"))) {
 107                 if (asprintf(&config_home, "%s/systemd/session", e) < 0)
 108                         goto fail;
 109
 110         } else if (home) {
 111                 if (asprintf(&config_home, "%s/.config/systemd/session", home) < 0)
 112                         goto fail;
 113         }
 114
 115         if ((e = getenv("XDG_CONFIG_DIRS")))
 116                 config_dirs = strv_split(e, ":");
 117         else
 118                 config_dirs = strv_new("/etc/xdg", NULL);
 119
 120         if (!config_dirs)
 121                 goto fail;
 122
 123         if ((e = getenv("XDG_DATA_HOME"))) {
 124                 if (asprintf(&data_home, "%s/systemd/session", e) < 0)
 125                         goto fail;
 126
 127         } else if (home) {
 128                 if (asprintf(&data_home, "%s/.local/share/systemd/session", home) < 0)
 129                         goto fail;
 130         }
 131
 132         if ((e = getenv("XDG_DATA_DIRS")))
 133                 data_dirs = strv_split(e, ":");
 134         else
 135                 data_dirs = strv_new("/usr/local/share", "/usr/share", NULL);
 136
 137         if (!data_dirs)
 138                 goto fail;
 139
 140         /* Now merge everything we found. */
 141         if (config_home) {
 142                 if (!(t = strv_append(r, config_home)))
 143                         goto fail;
 144                 strv_free(r);
 145                 r = t;
 146         }
 147
 148         if (!(t = strv_merge_concat(r, config_dirs, "/systemd/session")))
 149                 goto finish;
 150         strv_free(r);
 151         r = t;
 152
 153         if (!(t = strv_append(r, SESSION_CONFIG_UNIT_PATH)))
 154                 goto fail;
 155         strv_free(r);
 156         r = t;
 157
 158         if (data_home) {
 159                 if (!(t = strv_append(r, data_home)))
 160                         goto fail;
 161                 strv_free(r);
 162                 r = t;
 163         }
 164
 165         if (!(t = strv_merge_concat(r, data_dirs, "/systemd/session")))
 166                 goto fail;
 167         strv_free(r);
 168         r = t;
 169
 170         if (!(t = strv_append(r, SESSION_DATA_UNIT_PATH)))
 171                 goto fail;
 172         strv_free(r);
 173         r = t;
 174
 175         if (!strv_path_make_absolute_cwd(r))
 176             goto fail;
 177
 178 finish:
 179         free(config_home);
 180         strv_free(config_dirs);
 181         free(data_home);
 182         strv_free(data_dirs);
 183
 184         return r;
 185
 186 fail:
 187         strv_free(r);
 188         r = NULL;
 189         goto finish;
 190 }
 191
 192 static int manager_find_paths(Manager *m) {
 193         const char *e;
 194         char *t;
 195
 196         assert(m);
 197
 198         /* First priority is whatever has been passed to us via env
 199          * vars */
 200         if ((e = getenv("SYSTEMD_UNIT_PATH")))
 201                 if (!(m->unit_path = split_path_and_make_absolute(e)))
 202                         return -ENOMEM;
 203
 204         if (strv_isempty(m->unit_path)) {
 205
 206                 /* Nothing is set, so let's figure something out. */
 207                 strv_free(m->unit_path);
 208
 209                 if (m->running_as == MANAGER_SESSION) {
 210                         if (!(m->unit_path = session_dirs()))
 211                                 return -ENOMEM;
 212                 } else
 213                         if (!(m->unit_path = strv_new(
 214                                               SYSTEM_CONFIG_UNIT_PATH,  /* /etc/systemd/system/ */
 215                                               SYSTEM_DATA_UNIT_PATH,    /* /lib/systemd/system/ */
 216                                               NULL)))
 217                                 return -ENOMEM;
 218         }
 219
 220         if (m->running_as == MANAGER_INIT) {
 221                 /* /etc/init.d/ compativility does not matter to users */
 222
 223                 if ((e = getenv("SYSTEMD_SYSVINIT_PATH")))
 224                         if (!(m->sysvinit_path = split_path_and_make_absolute(e)))
 225                                 return -ENOMEM;
 226
 227                 if (strv_isempty(m->sysvinit_path)) {
 228                         strv_free(m->sysvinit_path);
 229
 230                         if (!(m->sysvinit_path = strv_new(
 231                                               SYSTEM_SYSVINIT_PATH,     /* /etc/init.d/ */
 232                                               NULL)))
 233                                 return -ENOMEM;
 234                 }
 235         }
 236
 237         strv_uniq(m->unit_path);
 238         strv_uniq(m->sysvinit_path);
 239
 240         assert(!strv_isempty(m->unit_path));
 241         if (!(t = strv_join(m->unit_path, "\n\t")))
 242                 return -ENOMEM;
 243         log_debug("Looking for unit files in:\n\t%s", t);
 244         free(t);
 245
 246         if (!strv_isempty(m->sysvinit_path)) {
 247
 248                 if (!(t = strv_join(m->sysvinit_path, "\n\t")))
 249                         return -ENOMEM;
 250
 251                 log_debug("Looking for SysV init scripts in:\n\t%s", t);
 252                 free(t);
 253         } else
 254                 log_debug("Ignoring SysV init scripts.");
 255
 256         return 0;
 257 }
 258
 259 int manager_new(Manager **_m) {
 260         Manager *m;
 261         int r = -ENOMEM;
 262
 263         assert(_m);
 264
 265         if (!(m = new0(Manager, 1)))
 266                 return -ENOMEM;
 267
 268         m->signal_watch.fd = m->mount_watch.fd = m->udev_watch.fd = m->epoll_fd = -1;
 269         m->current_job_id = 1; /* start as id #1, so that we can leave #0 around as "null-like" value */
 270
 271         if (!(m->units = hashmap_new(string_hash_func, string_compare_func)))
 272                 goto fail;
 273
 274         if (!(m->jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
 275                 goto fail;
 276
 277         if (!(m->transaction_jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
 278                 goto fail;
 279
 280         if (!(m->watch_pids = hashmap_new(trivial_hash_func, trivial_compare_func)))
 281                 goto fail;
 282
 283         if (!(m->cgroup_bondings = hashmap_new(string_hash_func, string_compare_func)))
 284                 goto fail;
 285
 286         if ((m->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0)
 287                 goto fail;
 288
 289         if (getpid() == 1)
 290                 m->running_as = MANAGER_INIT;
 291         else if (getuid() == 0)
 292                 m->running_as = MANAGER_SYSTEM;
 293         else
 294                 m->running_as = MANAGER_SESSION;
 295
 296         log_debug("systemd running in %s mode.", manager_running_as_to_string(m->running_as));
 297
 298         if ((r = manager_find_paths(m)) < 0)
 299                 goto fail;
 300
 301         if ((r = manager_setup_signals(m)) < 0)
 302                 goto fail;
 303
 304         if ((r = manager_setup_cgroup(m)) < 0)
 305                 goto fail;
 306
 307         /* Try to connect to the busses, if possible. */
 308         if ((r = bus_init_system(m)) < 0 ||
 309             (r = bus_init_api(m)) < 0)
 310                 goto fail;
 311
 312         *_m = m;
 313         return 0;
 314
 315 fail:
 316         manager_free(m);
 317         return r;
 318 }
 319
 320 static unsigned manager_dispatch_cleanup_queue(Manager *m) {
 321         Meta *meta;
 322         unsigned n = 0;
 323
 324         assert(m);
 325
 326         while ((meta = m->cleanup_queue)) {
 327                 assert(meta->in_cleanup_queue);
 328
 329                 unit_free(UNIT(meta));
 330                 n++;
 331         }
 332
 333         return n;
 334 }
 335
 336 void manager_free(Manager *m) {
 337         UnitType c;
 338         Unit *u;
 339         Job *j;
 340
 341         assert(m);
 342
 343         while ((j = hashmap_first(m->transaction_jobs)))
 344                 job_free(j);
 345
 346         while ((u = hashmap_first(m->units)))
 347                 unit_free(u);
 348
 349         manager_dispatch_cleanup_queue(m);
 350
 351         for (c = 0; c < _UNIT_TYPE_MAX; c++)
 352                 if (unit_vtable[c]->shutdown)
 353                         unit_vtable[c]->shutdown(m);
 354
 355         manager_shutdown_cgroup(m);
 356
 357         bus_done_api(m);
 358         bus_done_system(m);
 359
 360         hashmap_free(m->units);
 361         hashmap_free(m->jobs);
 362         hashmap_free(m->transaction_jobs);
 363         hashmap_free(m->watch_pids);
 364
 365         if (m->epoll_fd >= 0)
 366                 close_nointr(m->epoll_fd);
 367         if (m->signal_watch.fd >= 0)
 368                 close_nointr(m->signal_watch.fd);
 369
 370         strv_free(m->unit_path);
 371         strv_free(m->sysvinit_path);
 372
 373         free(m->cgroup_controller);
 374         free(m->cgroup_hierarchy);
 375
 376         assert(hashmap_isempty(m->cgroup_bondings));
 377         hashmap_free(m->cgroup_bondings);
 378
 379         free(m);
 380 }
 381
 382 int manager_coldplug(Manager *m) {
 383         int r;
 384         UnitType c;
 385         Iterator i;
 386         Unit *u;
 387         char *k;
 388
 389         assert(m);
 390
 391         /* First, let's ask every type to load all units from
 392          * disk/kernel that it might know */
 393         for (c = 0; c < _UNIT_TYPE_MAX; c++)
 394                 if (unit_vtable[c]->enumerate)
 395                         if ((r = unit_vtable[c]->enumerate(m)) < 0)
 396                                 return r;
 397
 398         manager_dispatch_load_queue(m);
 399
 400         /* Then, let's set up their initial state. */
 401         HASHMAP_FOREACH_KEY(u, k, m->units, i) {
 402
 403                 /* ignore aliases */
 404                 if (unit_id(u) != k)
 405                         continue;
 406
 407                 if (UNIT_VTABLE(u)->coldplug)
 408                         if ((r = UNIT_VTABLE(u)->coldplug(u)) < 0)
 409                                 return r;
 410         }
 411
 412         return 0;
 413 }
 414
 415 static void transaction_delete_job(Manager *m, Job *j, bool delete_dependencies) {
 416         assert(m);
 417         assert(j);
 418
 419         /* Deletes one job from the transaction */
 420
 421         manager_transaction_unlink_job(m, j, delete_dependencies);
 422
 423         if (!j->installed)
 424                 job_free(j);
 425 }
 426
 427 static void transaction_delete_unit(Manager *m, Unit *u) {
 428         Job *j;
 429
 430         /* Deletes all jobs associated with a certain unit from the
 431          * transaction */
 432
 433         while ((j = hashmap_get(m->transaction_jobs, u)))
 434                 transaction_delete_job(m, j, true);
 435 }
 436
 437 static void transaction_clean_dependencies(Manager *m) {
 438         Iterator i;
 439         Job *j;
 440
 441         assert(m);
 442
 443         /* Drops all dependencies of all installed jobs */
 444
 445         HASHMAP_FOREACH(j, m->jobs, i) {
 446                 while (j->subject_list)
 447                         job_dependency_free(j->subject_list);
 448                 while (j->object_list)
 449                         job_dependency_free(j->object_list);
 450         }
 451
 452         assert(!m->transaction_anchor);
 453 }
 454
 455 static void transaction_abort(Manager *m) {
 456         Job *j;
 457
 458         assert(m);
 459
 460         while ((j = hashmap_first(m->transaction_jobs)))
 461                 if (j->installed)
 462                         transaction_delete_job(m, j, true);
 463                 else
 464                         job_free(j);
 465
 466         assert(hashmap_isempty(m->transaction_jobs));
 467
 468         transaction_clean_dependencies(m);
 469 }
 470
 471 static void transaction_find_jobs_that_matter_to_anchor(Manager *m, Job *j, unsigned generation) {
 472         JobDependency *l;
 473
 474         assert(m);
 475
 476         /* A recursive sweep through the graph that marks all units
 477          * that matter to the anchor job, i.e. are directly or
 478          * indirectly a dependency of the anchor job via paths that
 479          * are fully marked as mattering. */
 480
 481         if (j)
 482                 l = j->subject_list;
 483         else
 484                 l = m->transaction_anchor;
 485
 486         LIST_FOREACH(subject, l, l) {
 487
 488                 /* This link does not matter */
 489                 if (!l->matters)
 490                         continue;
 491
 492                 /* This unit has already been marked */
 493                 if (l->object->generation == generation)
 494                         continue;
 495
 496                 l->object->matters_to_anchor = true;
 497                 l->object->generation = generation;
 498
 499                 transaction_find_jobs_that_matter_to_anchor(m, l->object, generation);
 500         }
 501 }
 502
 503 static void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, JobType t) {
 504         JobDependency *l, *last;
 505
 506         assert(j);
 507         assert(other);
 508         assert(j->unit == other->unit);
 509         assert(!j->installed);
 510
 511         /* Merges 'other' into 'j' and then deletes j. */
 512
 513         j->type = t;
 514         j->state = JOB_WAITING;
 515         j->forced = j->forced || other->forced;
 516
 517         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
 518
 519         /* Patch us in as new owner of the JobDependency objects */
 520         last = NULL;
 521         LIST_FOREACH(subject, l, other->subject_list) {
 522                 assert(l->subject == other);
 523                 l->subject = j;
 524                 last = l;
 525         }
 526
 527         /* Merge both lists */
 528         if (last) {
 529                 last->subject_next = j->subject_list;
 530                 if (j->subject_list)
 531                         j->subject_list->subject_prev = last;
 532                 j->subject_list = other->subject_list;
 533         }
 534
 535         /* Patch us in as new owner of the JobDependency objects */
 536         last = NULL;
 537         LIST_FOREACH(object, l, other->object_list) {
 538                 assert(l->object == other);
 539                 l->object = j;
 540                 last = l;
 541         }
 542
 543         /* Merge both lists */
 544         if (last) {
 545                 last->object_next = j->object_list;
 546                 if (j->object_list)
 547                         j->object_list->object_prev = last;
 548                 j->object_list = other->object_list;
 549         }
 550
 551         /* Kill the other job */
 552         other->subject_list = NULL;
 553         other->object_list = NULL;
 554         transaction_delete_job(m, other, true);
 555 }
 556
 557 static int delete_one_unmergeable_job(Manager *m, Job *j) {
 558         Job *k;
 559
 560         assert(j);
 561
 562         /* Tries to delete one item in the linked list
 563          * j->transaction_next->transaction_next->... that conflicts
 564          * whith another one, in an attempt to make an inconsistent
 565          * transaction work. */
 566
 567         /* We rely here on the fact that if a merged with b does not
 568          * merge with c, either a or b merge with c neither */
 569         LIST_FOREACH(transaction, j, j)
 570                 LIST_FOREACH(transaction, k, j->transaction_next) {
 571                         Job *d;
 572
 573                         /* Is this one mergeable? Then skip it */
 574                         if (job_type_is_mergeable(j->type, k->type))
 575                                 continue;
 576
 577                         /* Ok, we found two that conflict, let's see if we can
 578                          * drop one of them */
 579                         if (!j->matters_to_anchor)
 580                                 d = j;
 581                         else if (!k->matters_to_anchor)
 582                                 d = k;
 583                         else
 584                                 return -ENOEXEC;
 585
 586                         /* Ok, we can drop one, so let's do so. */
 587                         log_debug("Trying to fix job merging by deleting job %s/%s", unit_id(d->unit), job_type_to_string(d->type));
 588                         transaction_delete_job(m, d, true);
 589                         return 0;
 590                 }
 591
 592         return -EINVAL;
 593 }
 594
 595 static int transaction_merge_jobs(Manager *m) {
 596         Job *j;
 597         Iterator i;
 598         int r;
 599
 600         assert(m);
 601
 602         /* First step, check whether any of the jobs for one specific
 603          * task conflict. If so, try to drop one of them. */
 604         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 605                 JobType t;
 606                 Job *k;
 607
 608                 t = j->type;
 609                 LIST_FOREACH(transaction, k, j->transaction_next) {
 610                         if ((r = job_type_merge(&t, k->type)) >= 0)
 611                                 continue;
 612
 613                         /* OK, we could not merge all jobs for this
 614                          * action. Let's see if we can get rid of one
 615                          * of them */
 616
 617                         if ((r = delete_one_unmergeable_job(m, j)) >= 0)
 618                                 /* Ok, we managed to drop one, now
 619                                  * let's ask our callers to call us
 620                                  * again after garbage collecting */
 621                                 return -EAGAIN;
 622
 623                         /* We couldn't merge anything. Failure */
 624                         return r;
 625                 }
 626         }
 627
 628         /* Second step, merge the jobs. */
 629         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 630                 JobType t = j->type;
 631                 Job *k;
 632
 633                 /* Merge all transactions */
 634                 LIST_FOREACH(transaction, k, j->transaction_next)
 635                         assert_se(job_type_merge(&t, k->type) == 0);
 636
 637                 /* If an active job is mergeable, merge it too */
 638                 if (j->unit->meta.job)
 639                         job_type_merge(&t, j->unit->meta.job->type); /* Might fail. Which is OK */
 640
 641                 while ((k = j->transaction_next)) {
 642                         if (j->installed) {
 643                                 transaction_merge_and_delete_job(m, k, j, t);
 644                                 j = k;
 645                         } else
 646                                 transaction_merge_and_delete_job(m, j, k, t);
 647                 }
 648
 649                 assert(!j->transaction_next);
 650                 assert(!j->transaction_prev);
 651         }
 652
 653         return 0;
 654 }
 655
 656 static void transaction_drop_redundant(Manager *m) {
 657         bool again;
 658
 659         assert(m);
 660
 661         /* Goes through the transaction and removes all jobs that are
 662          * a noop */
 663
 664         do {
 665                 Job *j;
 666                 Iterator i;
 667
 668                 again = false;
 669
 670                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 671                         bool changes_something = false;
 672                         Job *k;
 673
 674                         LIST_FOREACH(transaction, k, j) {
 675
 676                                 if (!job_is_anchor(k) &&
 677                                     job_type_is_redundant(k->type, unit_active_state(k->unit)))
 678                                         continue;
 679
 680                                 changes_something = true;
 681                                 break;
 682                         }
 683
 684                         if (changes_something)
 685                                 continue;
 686
 687                         log_debug("Found redundant job %s/%s, dropping.", unit_id(j->unit), job_type_to_string(j->type));
 688                         transaction_delete_job(m, j, false);
 689                         again = true;
 690                         break;
 691                 }
 692
 693         } while (again);
 694 }
 695
 696 static bool unit_matters_to_anchor(Unit *u, Job *j) {
 697         assert(u);
 698         assert(!j->transaction_prev);
 699
 700         /* Checks whether at least one of the jobs for this unit
 701          * matters to the anchor. */
 702
 703         LIST_FOREACH(transaction, j, j)
 704                 if (j->matters_to_anchor)
 705                         return true;
 706
 707         return false;
 708 }
 709
 710 static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
 711         Iterator i;
 712         Unit *u;
 713         int r;
 714
 715         assert(m);
 716         assert(j);
 717         assert(!j->transaction_prev);
 718
 719         /* Does a recursive sweep through the ordering graph, looking
 720          * for a cycle. If we find cycle we try to break it. */
 721
 722         /* Did we find a cycle? */
 723         if (j->marker && j->generation == generation) {
 724                 Job *k;
 725
 726                 /* So, we already have been here. We have a
 727                  * cycle. Let's try to break it. We go backwards in
 728                  * our path and try to find a suitable job to
 729                  * remove. We use the marker to find our way back,
 730                  * since smart how we are we stored our way back in
 731                  * there. */
 732
 733                 log_debug("Found ordering cycle on %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 734
 735                 for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
 736
 737                         log_debug("Walked on cycle path to %s/%s", unit_id(k->unit), job_type_to_string(k->type));
 738
 739                         if (!k->installed &&
 740                             !unit_matters_to_anchor(k->unit, k)) {
 741                                 /* Ok, we can drop this one, so let's
 742                                  * do so. */
 743                                 log_debug("Breaking order cycle by deleting job %s/%s", unit_id(k->unit), job_type_to_string(k->type));
 744                                 transaction_delete_unit(m, k->unit);
 745                                 return -EAGAIN;
 746                         }
 747
 748                         /* Check if this in fact was the beginning of
 749                          * the cycle */
 750                         if (k == j)
 751                                 break;
 752                 }
 753
 754                 log_debug("Unable to break cycle");
 755
 756                 return -ENOEXEC;
 757         }
 758
 759         /* Make the marker point to where we come from, so that we can
 760          * find our way backwards if we want to break a cycle */
 761         j->marker = from;
 762         j->generation = generation;
 763
 764         /* We assume that the the dependencies are bidirectional, and
 765          * hence can ignore UNIT_AFTER */
 766         SET_FOREACH(u, j->unit->meta.dependencies[UNIT_BEFORE], i) {
 767                 Job *o;
 768
 769                 /* Is there a job for this unit? */
 770                 if (!(o = hashmap_get(m->transaction_jobs, u)))
 771
 772                         /* Ok, there is no job for this in the
 773                          * transaction, but maybe there is already one
 774                          * running? */
 775                         if (!(o = u->meta.job))
 776                                 continue;
 777
 778                 if ((r = transaction_verify_order_one(m, o, j, generation)) < 0)
 779                         return r;
 780         }
 781
 782         /* Ok, let's backtrack, and remember that this entry is not on
 783          * our path anymore. */
 784         j->marker = NULL;
 785
 786         return 0;
 787 }
 788
 789 static int transaction_verify_order(Manager *m, unsigned *generation) {
 790         Job *j;
 791         int r;
 792         Iterator i;
 793
 794         assert(m);
 795         assert(generation);
 796
 797         /* Check if the ordering graph is cyclic. If it is, try to fix
 798          * that up by dropping one of the jobs. */
 799
 800         HASHMAP_FOREACH(j, m->transaction_jobs, i)
 801                 if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
 802                         return r;
 803
 804         return 0;
 805 }
 806
 807 static void transaction_collect_garbage(Manager *m) {
 808         bool again;
 809
 810         assert(m);
 811
 812         /* Drop jobs that are not required by any other job */
 813
 814         do {
 815                 Iterator i;
 816                 Job *j;
 817
 818                 again = false;
 819
 820                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 821                         if (j->object_list)
 822                                 continue;
 823
 824                         log_debug("Garbage collecting job %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 825                         transaction_delete_job(m, j, true);
 826                         again = true;
 827                         break;
 828                 }
 829
 830         } while (again);
 831 }
 832
 833 static int transaction_is_destructive(Manager *m, JobMode mode) {
 834         Iterator i;
 835         Job *j;
 836
 837         assert(m);
 838
 839         /* Checks whether applying this transaction means that
 840          * existing jobs would be replaced */
 841
 842         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 843
 844                 /* Assume merged */
 845                 assert(!j->transaction_prev);
 846                 assert(!j->transaction_next);
 847
 848                 if (j->unit->meta.job &&
 849                     j->unit->meta.job != j &&
 850                     !job_type_is_superset(j->type, j->unit->meta.job->type))
 851                         return -EEXIST;
 852         }
 853
 854         return 0;
 855 }
 856
 857 static void transaction_minimize_impact(Manager *m) {
 858         bool again;
 859         assert(m);
 860
 861         /* Drops all unnecessary jobs that reverse already active jobs
 862          * or that stop a running service. */
 863
 864         do {
 865                 Job *j;
 866                 Iterator i;
 867
 868                 again = false;
 869
 870                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 871                         LIST_FOREACH(transaction, j, j) {
 872                                 bool stops_running_service, changes_existing_job;
 873
 874                                 /* If it matters, we shouldn't drop it */
 875                                 if (j->matters_to_anchor)
 876                                         continue;
 877
 878                                 /* Would this stop a running service?
 879                                  * Would this change an existing job?
 880                                  * If so, let's drop this entry */
 881
 882                                 stops_running_service =
 883                                         j->type == JOB_STOP && UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(j->unit));
 884
 885                                 changes_existing_job =
 886                                         j->unit->meta.job && job_type_is_conflicting(j->type, j->unit->meta.job->state);
 887
 888                                 if (!stops_running_service && !changes_existing_job)
 889                                         continue;
 890
 891                                 if (stops_running_service)
 892                                         log_debug("%s/%s would stop a running service.", unit_id(j->unit), job_type_to_string(j->type));
 893
 894                                 if (changes_existing_job)
 895                                         log_debug("%s/%s would change existing job.", unit_id(j->unit), job_type_to_string(j->type));
 896
 897                                 /* Ok, let's get rid of this */
 898                                 log_debug("Deleting %s/%s to minimize impact.", unit_id(j->unit), job_type_to_string(j->type));
 899
 900                                 transaction_delete_job(m, j, true);
 901                                 again = true;
 902                                 break;
 903                         }
 904
 905                         if (again)
 906                                 break;
 907                 }
 908
 909         } while (again);
 910 }
 911
 912 static int transaction_apply(Manager *m, JobMode mode) {
 913         Iterator i;
 914         Job *j;
 915         int r;
 916
 917         /* Moves the transaction jobs to the set of active jobs */
 918
 919         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 920                 /* Assume merged */
 921                 assert(!j->transaction_prev);
 922                 assert(!j->transaction_next);
 923
 924                 if (j->installed)
 925                         continue;
 926
 927                 if ((r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j)) < 0)
 928                         goto rollback;
 929         }
 930
 931         while ((j = hashmap_steal_first(m->transaction_jobs))) {
 932                 if (j->installed)
 933                         continue;
 934
 935                 if (j->unit->meta.job)
 936                         job_free(j->unit->meta.job);
 937
 938                 j->unit->meta.job = j;
 939                 j->installed = true;
 940
 941                 /* We're fully installed. Now let's free data we don't
 942                  * need anymore. */
 943
 944                 assert(!j->transaction_next);
 945                 assert(!j->transaction_prev);
 946
 947                 job_add_to_run_queue(j);
 948                 job_add_to_dbus_queue(j);
 949         }
 950
 951         /* As last step, kill all remaining job dependencies. */
 952         transaction_clean_dependencies(m);
 953
 954         return 0;
 955
 956 rollback:
 957
 958         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 959                 if (j->installed)
 960                         continue;
 961
 962                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 963         }
 964
 965         return r;
 966 }
 967
 968 static int transaction_activate(Manager *m, JobMode mode) {
 969         int r;
 970         unsigned generation = 1;
 971
 972         assert(m);
 973
 974         /* This applies the changes recorded in transaction_jobs to
 975          * the actual list of jobs, if possible. */
 976
 977         /* First step: figure out which jobs matter */
 978         transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
 979
 980         /* Second step: Try not to stop any running services if
 981          * we don't have to. Don't try to reverse running
 982          * jobs if we don't have to. */
 983         transaction_minimize_impact(m);
 984
 985         /* Third step: Drop redundant jobs */
 986         transaction_drop_redundant(m);
 987
 988         for (;;) {
 989                 /* Fourth step: Let's remove unneeded jobs that might
 990                  * be lurking. */
 991                 transaction_collect_garbage(m);
 992
 993                 /* Fifth step: verify order makes sense and correct
 994                  * cycles if necessary and possible */
 995                 if ((r = transaction_verify_order(m, &generation)) >= 0)
 996                         break;
 997
 998                 if (r != -EAGAIN) {
 999                         log_debug("Requested transaction contains an unfixable cyclic ordering dependency: %s", strerror(-r));
1000                         goto rollback;
1001                 }
1002
1003                 /* Let's see if the resulting transaction ordering
1004                  * graph is still cyclic... */
1005         }
1006
1007         for (;;) {
1008                 /* Sixth step: let's drop unmergeable entries if
1009                  * necessary and possible, merge entries we can
1010                  * merge */
1011                 if ((r = transaction_merge_jobs(m)) >= 0)
1012                         break;
1013
1014                 if (r != -EAGAIN) {
1015                         log_debug("Requested transaction contains unmergable jobs: %s", strerror(-r));
1016                         goto rollback;
1017                 }
1018
1019                 /* Seventh step: an entry got dropped, let's garbage
1020                  * collect its dependencies. */
1021                 transaction_collect_garbage(m);
1022
1023                 /* Let's see if the resulting transaction still has
1024                  * unmergeable entries ... */
1025         }
1026
1027         /* Eights step: Drop redundant jobs again, if the merging now allows us to drop more. */
1028         transaction_drop_redundant(m);
1029
1030         /* Ninth step: check whether we can actually apply this */
1031         if (mode == JOB_FAIL)
1032                 if ((r = transaction_is_destructive(m, mode)) < 0) {
1033                         log_debug("Requested transaction contradicts existing jobs: %s", strerror(-r));
1034                         goto rollback;
1035                 }
1036
1037         /* Tenth step: apply changes */
1038         if ((r = transaction_apply(m, mode)) < 0) {
1039                 log_debug("Failed to apply transaction: %s", strerror(-r));
1040                 goto rollback;
1041         }
1042
1043         assert(hashmap_isempty(m->transaction_jobs));
1044         assert(!m->transaction_anchor);
1045
1046         return 0;
1047
1048 rollback:
1049         transaction_abort(m);
1050         return r;
1051 }
1052
1053 static Job* transaction_add_one_job(Manager *m, JobType type, Unit *unit, bool force, bool *is_new) {
1054         Job *j, *f;
1055         int r;
1056
1057         assert(m);
1058         assert(unit);
1059
1060         /* Looks for an axisting prospective job and returns that. If
1061          * it doesn't exist it is created and added to the prospective
1062          * jobs list. */
1063
1064         f = hashmap_get(m->transaction_jobs, unit);
1065
1066         LIST_FOREACH(transaction, j, f) {
1067                 assert(j->unit == unit);
1068
1069                 if (j->type == type) {
1070                         if (is_new)
1071                                 *is_new = false;
1072                         return j;
1073                 }
1074         }
1075
1076         if (unit->meta.job && unit->meta.job->type == type)
1077                 j = unit->meta.job;
1078         else if (!(j = job_new(m, type, unit)))
1079                 return NULL;
1080
1081         j->generation = 0;
1082         j->marker = NULL;
1083         j->matters_to_anchor = false;
1084         j->forced = force;
1085
1086         LIST_PREPEND(Job, transaction, f, j);
1087
1088         if ((r = hashmap_replace(m->transaction_jobs, unit, f)) < 0) {
1089                 job_free(j);
1090                 return NULL;
1091         }
1092
1093         if (is_new)
1094                 *is_new = true;
1095
1096         log_debug("Added job %s/%s to transaction.", unit_id(unit), job_type_to_string(type));
1097
1098         return j;
1099 }
1100
1101 void manager_transaction_unlink_job(Manager *m, Job *j, bool delete_dependencies) {
1102         assert(m);
1103         assert(j);
1104
1105         if (j->transaction_prev)
1106                 j->transaction_prev->transaction_next = j->transaction_next;
1107         else if (j->transaction_next)
1108                 hashmap_replace(m->transaction_jobs, j->unit, j->transaction_next);
1109         else
1110                 hashmap_remove_value(m->transaction_jobs, j->unit, j);
1111
1112         if (j->transaction_next)
1113                 j->transaction_next->transaction_prev = j->transaction_prev;
1114
1115         j->transaction_prev = j->transaction_next = NULL;
1116
1117         while (j->subject_list)
1118                 job_dependency_free(j->subject_list);
1119
1120         while (j->object_list) {
1121                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
1122
1123                 job_dependency_free(j->object_list);
1124
1125                 if (other && delete_dependencies) {
1126                         log_debug("Deleting job %s/%s as dependency of job %s/%s",
1127                                   unit_id(other->unit), job_type_to_string(other->type),
1128                                   unit_id(j->unit), job_type_to_string(j->type));
1129                         transaction_delete_job(m, other, delete_dependencies);
1130                 }
1131         }
1132 }
1133
1134 static int transaction_add_job_and_dependencies(Manager *m, JobType type, Unit *unit, Job *by, bool matters, bool force, Job **_ret) {
1135         Job *ret;
1136         Iterator i;
1137         Unit *dep;
1138         int r;
1139         bool is_new;
1140
1141         assert(m);
1142         assert(type < _JOB_TYPE_MAX);
1143         assert(unit);
1144
1145         if (unit->meta.load_state != UNIT_LOADED)
1146                 return -EINVAL;
1147
1148         if (!unit_job_is_applicable(unit, type))
1149                 return -EBADR;
1150
1151         /* First add the job. */
1152         if (!(ret = transaction_add_one_job(m, type, unit, force, &is_new)))
1153                 return -ENOMEM;
1154
1155         /* Then, add a link to the job. */
1156         if (!job_dependency_new(by, ret, matters))
1157                 return -ENOMEM;
1158
1159         if (is_new) {
1160                 /* Finally, recursively add in all dependencies. */
1161                 if (type == JOB_START || type == JOB_RELOAD_OR_START) {
1162                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRES], i)
1163                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
1164                                         goto fail;
1165                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUIRES], i)
1166                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
1167                                         goto fail;
1168                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_WANTS], i)
1169                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, force, NULL)) < 0)
1170                                         log_warning("Cannot add dependency job for unit %s, ignoring: %s", unit_id(dep), strerror(-r));
1171                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUISITE], i)
1172                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
1173                                         goto fail;
1174                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUISITE], i)
1175                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
1176                                         goto fail;
1177                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_CONFLICTS], i)
1178                                 if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
1179                                         goto fail;
1180
1181                 } else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
1182
1183                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRED_BY], i)
1184                                 if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
1185                                         goto fail;
1186                 }
1187
1188                 /* JOB_VERIFY_STARTED, JOB_RELOAD require no dependency handling */
1189         }
1190
1191         if (_ret)
1192                 *_ret = ret;
1193
1194         return 0;
1195
1196 fail:
1197         return r;
1198 }
1199
1200 int manager_add_job(Manager *m, JobType type, Unit *unit, JobMode mode, bool force, Job **_ret) {
1201         int r;
1202         Job *ret;
1203
1204         assert(m);
1205         assert(type < _JOB_TYPE_MAX);
1206         assert(unit);
1207         assert(mode < _JOB_MODE_MAX);
1208
1209         log_debug("Trying to enqueue job %s/%s", unit_id(unit), job_type_to_string(type));
1210
1211         if ((r = transaction_add_job_and_dependencies(m, type, unit, NULL, true, force, &ret)) < 0) {
1212                 transaction_abort(m);
1213                 return r;
1214         }
1215
1216         if ((r = transaction_activate(m, mode)) < 0)
1217                 return r;
1218
1219         log_debug("Enqueued job %s/%s as %u", unit_id(unit), job_type_to_string(type), (unsigned) ret->id);
1220
1221         if (_ret)
1222                 *_ret = ret;
1223
1224         return 0;
1225 }
1226
1227 Job *manager_get_job(Manager *m, uint32_t id) {
1228         assert(m);
1229
1230         return hashmap_get(m->jobs, UINT32_TO_PTR(id));
1231 }
1232
1233 Unit *manager_get_unit(Manager *m, const char *name) {
1234         assert(m);
1235         assert(name);
1236
1237         return hashmap_get(m->units, name);
1238 }
1239
1240 unsigned manager_dispatch_load_queue(Manager *m) {
1241         Meta *meta;
1242         unsigned n = 0;
1243
1244         assert(m);
1245
1246         /* Make sure we are not run recursively */
1247         if (m->dispatching_load_queue)
1248                 return 0;
1249
1250         m->dispatching_load_queue = true;
1251
1252         /* Dispatches the load queue. Takes a unit from the queue and
1253          * tries to load its data until the queue is empty */
1254
1255         while ((meta = m->load_queue)) {
1256                 assert(meta->in_load_queue);
1257
1258                 unit_load(UNIT(meta));
1259                 n++;
1260         }
1261
1262         m->dispatching_load_queue = false;
1263         return n;
1264 }
1265
1266 int manager_load_unit(Manager *m, const char *path, Unit **_ret) {
1267         Unit *ret;
1268         int r;
1269         const char *name;
1270
1271         assert(m);
1272         assert(path);
1273         assert(_ret);
1274
1275         /* This will load the service information files, but not actually
1276          * start any services or anything. */
1277
1278         name = file_name_from_path(path);
1279
1280         if ((ret = manager_get_unit(m, name))) {
1281                 *_ret = ret;
1282                 return 0;
1283         }
1284
1285         if (!(ret = unit_new(m)))
1286                 return -ENOMEM;
1287
1288         if (is_path(path)) {
1289                 if (!(ret->meta.fragment_path = strdup(path))) {
1290                         unit_free(ret);
1291                         return -ENOMEM;
1292                 }
1293         }
1294
1295         if ((r = unit_add_name(ret, name)) < 0) {
1296                 unit_free(ret);
1297                 return r;
1298         }
1299
1300         unit_add_to_load_queue(ret);
1301         unit_add_to_dbus_queue(ret);
1302
1303         manager_dispatch_load_queue(m);
1304
1305         *_ret = unit_follow_merge(ret);
1306         return 0;
1307 }
1308
1309 void manager_dump_jobs(Manager *s, FILE *f, const char *prefix) {
1310         Iterator i;
1311         Job *j;
1312
1313         assert(s);
1314         assert(f);
1315
1316         HASHMAP_FOREACH(j, s->jobs, i)
1317                 job_dump(j, f, prefix);
1318 }
1319
1320 void manager_dump_units(Manager *s, FILE *f, const char *prefix) {
1321         Iterator i;
1322         Unit *u;
1323         const char *t;
1324
1325         assert(s);
1326         assert(f);
1327
1328         HASHMAP_FOREACH_KEY(u, t, s->units, i)
1329                 if (unit_id(u) == t)
1330                         unit_dump(u, f, prefix);
1331 }
1332
1333 void manager_clear_jobs(Manager *m) {
1334         Job *j;
1335
1336         assert(m);
1337
1338         transaction_abort(m);
1339
1340         while ((j = hashmap_first(m->jobs)))
1341                 job_free(j);
1342 }
1343
1344 unsigned manager_dispatch_run_queue(Manager *m) {
1345         Job *j;
1346         unsigned n = 0;
1347
1348         if (m->dispatching_run_queue)
1349                 return 0;
1350
1351         m->dispatching_run_queue = true;
1352
1353         while ((j = m->run_queue)) {
1354                 assert(j->installed);
1355                 assert(j->in_run_queue);
1356
1357                 job_run_and_invalidate(j);
1358                 n++;
1359         }
1360
1361         m->dispatching_run_queue = false;
1362         return n;
1363 }
1364
1365 unsigned manager_dispatch_dbus_queue(Manager *m) {
1366         Job *j;
1367         Meta *meta;
1368         unsigned n = 0;
1369
1370         assert(m);
1371
1372         if (m->dispatching_dbus_queue)
1373                 return 0;
1374
1375         m->dispatching_dbus_queue = true;
1376
1377         while ((meta = m->dbus_unit_queue)) {
1378                 assert(meta->in_dbus_queue);
1379
1380                 bus_unit_send_change_signal(UNIT(meta));
1381                 n++;
1382         }
1383
1384         while ((j = m->dbus_job_queue)) {
1385                 assert(j->in_dbus_queue);
1386
1387                 bus_job_send_change_signal(j);
1388                 n++;
1389         }
1390
1391         m->dispatching_dbus_queue = false;
1392         return n;
1393 }
1394
1395 static int manager_dispatch_sigchld(Manager *m) {
1396         assert(m);
1397
1398         log_debug("dispatching SIGCHLD");
1399
1400         for (;;) {
1401                 siginfo_t si;
1402                 Unit *u;
1403
1404                 zero(si);
1405                 if (waitid(P_ALL, 0, &si, WEXITED|WNOHANG) < 0) {
1406
1407                         if (errno == ECHILD)
1408                                 break;
1409
1410                         return -errno;
1411                 }
1412
1413                 if (si.si_pid == 0)
1414                         break;
1415
1416                 if (si.si_code != CLD_EXITED && si.si_code != CLD_KILLED && si.si_code != CLD_DUMPED)
1417                         continue;
1418
1419                 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);
1420
1421                 if (!(u = hashmap_remove(m->watch_pids, UINT32_TO_PTR(si.si_pid))))
1422                         continue;
1423
1424                 UNIT_VTABLE(u)->sigchld_event(u, si.si_pid, si.si_code, si.si_status);
1425         }
1426
1427         return 0;
1428 }
1429
1430 static int manager_process_signal_fd(Manager *m, bool *quit) {
1431         ssize_t n;
1432         struct signalfd_siginfo sfsi;
1433         bool sigchld = false;
1434
1435         assert(m);
1436
1437         for (;;) {
1438                 if ((n = read(m->signal_watch.fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
1439
1440                         if (n >= 0)
1441                                 return -EIO;
1442
1443                         if (errno == EAGAIN)
1444                                 break;
1445
1446                         return -errno;
1447                 }
1448
1449                 switch (sfsi.ssi_signo) {
1450
1451                 case SIGCHLD:
1452                         sigchld = true;
1453                         break;
1454
1455                 case SIGINT:
1456                 case SIGTERM:
1457
1458                         if (m->running_as != MANAGER_INIT) {
1459                                 *quit = true;
1460                                 return 0;
1461
1462                         } else {
1463                                 Unit *target;
1464                                 int r;
1465
1466                                 if ((r = manager_load_unit(m, SPECIAL_CTRL_ALT_DEL_TARGET, &target)) < 0)
1467                                         log_error("Failed to load ctrl-alt-del target: %s", strerror(-r));
1468                                 else if ((r = manager_add_job(m, JOB_START, target, JOB_REPLACE, true, NULL)) < 0)
1469                                         log_error("Failed to enqueue ctrl-alt-del job: %s", strerror(-r));
1470
1471                                 break;
1472                         }
1473
1474                 case SIGWINCH:
1475
1476                         if (m->running_as == MANAGER_INIT) {
1477                                 Unit *target;
1478                                 int r;
1479
1480                                 if ((r = manager_load_unit(m, SPECIAL_KBREQUEST_TARGET, &target)) < 0)
1481                                         log_error("Failed to load kbrequest target: %s", strerror(-r));
1482                                 else if ((r = manager_add_job(m, JOB_START, target, JOB_REPLACE, true, NULL)) < 0)
1483                                         log_error("Failed to enqueue kbrequest job: %s", strerror(-r));
1484
1485                                 break;
1486                         }
1487
1488                         /* This is a nop on non-init systemd's */
1489
1490                         break;
1491
1492                 case SIGUSR1:
1493
1494                         printf("→ By units:\n");
1495                         manager_dump_units(m, stdout, "\t");
1496
1497                         printf("→ By jobs:\n");
1498                         manager_dump_jobs(m, stdout, "\t");
1499
1500                         break;
1501
1502                 default:
1503                         log_info("Got unhandled signal <%s>.", strsignal(sfsi.ssi_signo));
1504                 }
1505         }
1506
1507         if (sigchld)
1508                 return manager_dispatch_sigchld(m);
1509
1510         return 0;
1511 }
1512
1513 static int process_event(Manager *m, struct epoll_event *ev, bool *quit) {
1514         int r;
1515         Watch *w;
1516
1517         assert(m);
1518         assert(ev);
1519
1520         assert(w = ev->data.ptr);
1521
1522         switch (w->type) {
1523
1524         case WATCH_SIGNAL:
1525
1526                 /* An incoming signal? */
1527                 if (ev->events != EPOLLIN)
1528                         return -EINVAL;
1529
1530                 if ((r = manager_process_signal_fd(m, quit)) < 0)
1531                         return r;
1532
1533                 break;
1534
1535         case WATCH_FD:
1536
1537                 /* Some fd event, to be dispatched to the units */
1538                 UNIT_VTABLE(w->data.unit)->fd_event(w->data.unit, w->fd, ev->events, w);
1539                 break;
1540
1541         case WATCH_TIMER: {
1542                 uint64_t v;
1543                 ssize_t k;
1544
1545                 /* Some timer event, to be dispatched to the units */
1546                 if ((k = read(w->fd, &v, sizeof(v))) != sizeof(v)) {
1547
1548                         if (k < 0 && (errno == EINTR || errno == EAGAIN))
1549                                 break;
1550
1551                         return k < 0 ? -errno : -EIO;
1552                 }
1553
1554                 UNIT_VTABLE(w->data.unit)->timer_event(w->data.unit, v, w);
1555                 break;
1556         }
1557
1558         case WATCH_MOUNT:
1559                 /* Some mount table change, intended for the mount subsystem */
1560                 mount_fd_event(m, ev->events);
1561                 break;
1562
1563         case WATCH_UDEV:
1564                 /* Some notification from udev, intended for the device subsystem */
1565                 device_fd_event(m, ev->events);
1566                 break;
1567
1568         case WATCH_DBUS_WATCH:
1569                 bus_watch_event(m, w, ev->events);
1570                 break;
1571
1572         case WATCH_DBUS_TIMEOUT:
1573                 bus_timeout_event(m, w, ev->events);
1574                 break;
1575
1576         default:
1577                 assert_not_reached("Unknown epoll event type.");
1578         }
1579
1580         return 0;
1581 }
1582
1583 int manager_loop(Manager *m) {
1584         int r;
1585         bool quit = false;
1586
1587         RATELIMIT_DEFINE(rl, 1*USEC_PER_SEC, 1000);
1588
1589         assert(m);
1590
1591         do {
1592                 struct epoll_event event;
1593                 int n;
1594
1595                 if (!ratelimit_test(&rl)) {
1596                         /* Yay, something is going seriously wrong, pause a little */
1597                         log_warning("Looping too fast. Throttling execution a little.");
1598                         sleep(1);
1599                 }
1600
1601                 if (manager_dispatch_cleanup_queue(m) > 0)
1602                         continue;
1603
1604                 if (manager_dispatch_load_queue(m) > 0)
1605                         continue;
1606
1607                 if (manager_dispatch_run_queue(m) > 0)
1608                         continue;
1609
1610                 if (bus_dispatch(m) > 0)
1611                         continue;
1612
1613                 if (manager_dispatch_dbus_queue(m) > 0)
1614                         continue;
1615
1616                 if ((n = epoll_wait(m->epoll_fd, &event, 1, -1)) < 0) {
1617
1618                         if (errno == -EINTR)
1619                                 continue;
1620
1621                         return -errno;
1622                 }
1623
1624                 assert(n == 1);
1625
1626                 if ((r = process_event(m, &event, &quit)) < 0)
1627                         return r;
1628         } while (!quit);
1629
1630         return 0;
1631 }
1632
1633 int manager_get_unit_from_dbus_path(Manager *m, const char *s, Unit **_u) {
1634         char *n;
1635         Unit *u;
1636
1637         assert(m);
1638         assert(s);
1639         assert(_u);
1640
1641         if (!startswith(s, "/org/freedesktop/systemd1/unit/"))
1642                 return -EINVAL;
1643
1644         if (!(n = bus_path_unescape(s+31)))
1645                 return -ENOMEM;
1646
1647         u = manager_get_unit(m, n);
1648         free(n);
1649
1650         if (!u)
1651                 return -ENOENT;
1652
1653         *_u = u;
1654
1655         return 0;
1656 }
1657
1658 int manager_get_job_from_dbus_path(Manager *m, const char *s, Job **_j) {
1659         Job *j;
1660         unsigned id;
1661         int r;
1662
1663         assert(m);
1664         assert(s);
1665         assert(_j);
1666
1667         if (!startswith(s, "/org/freedesktop/systemd1/job/"))
1668                 return -EINVAL;
1669
1670         if ((r = safe_atou(s + 30, &id)) < 0)
1671                 return r;
1672
1673         if (!(j = manager_get_job(m, id)))
1674                 return -ENOENT;
1675
1676         *_j = j;
1677
1678         return 0;
1679 }
1680
1681 static const char* const manager_running_as_table[_MANAGER_RUNNING_AS_MAX] = {
1682         [MANAGER_INIT] = "init",
1683         [MANAGER_SYSTEM] = "system",
1684         [MANAGER_SESSION] = "session"
1685 };
1686
1687 DEFINE_STRING_TABLE_LOOKUP(manager_running_as, ManagerRunningAs);