src/login/logind-core.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <fcntl.h>
   4 #include <pwd.h>
   5 #include <sys/ioctl.h>
   6 #include <sys/types.h>
   7 #include <linux/vt.h>
   8 #if ENABLE_UTMP
   9 #include <utmpx.h>
  10 #endif
  11
  12 #include "sd-device.h"
  13
  14 #include "alloc-util.h"
  15 #include "bus-error.h"
  16 #include "bus-util.h"
  17 #include "cgroup-util.h"
  18 #include "conf-parser.h"
  19 #include "device-util.h"
  20 #include "errno-util.h"
  21 #include "fd-util.h"
  22 #include "limits-util.h"
  23 #include "logind.h"
  24 #include "parse-util.h"
  25 #include "path-util.h"
  26 #include "process-util.h"
  27 #include "strv.h"
  28 #include "terminal-util.h"
  29 #include "udev-util.h"
  30 #include "user-util.h"
  31
  32 void manager_reset_config(Manager *m) {
  33         assert(m);
  34
  35         m->n_autovts = 6;
  36         m->reserve_vt = 6;
  37         m->remove_ipc = true;
  38         m->inhibit_delay_max = 5 * USEC_PER_SEC;
  39         m->user_stop_delay = 10 * USEC_PER_SEC;
  40
  41         m->handle_power_key = HANDLE_POWEROFF;
  42         m->handle_suspend_key = HANDLE_SUSPEND;
  43         m->handle_hibernate_key = HANDLE_HIBERNATE;
  44         m->handle_lid_switch = HANDLE_SUSPEND;
  45         m->handle_lid_switch_ep = _HANDLE_ACTION_INVALID;
  46         m->handle_lid_switch_docked = HANDLE_IGNORE;
  47         m->power_key_ignore_inhibited = false;
  48         m->suspend_key_ignore_inhibited = false;
  49         m->hibernate_key_ignore_inhibited = false;
  50         m->lid_switch_ignore_inhibited = true;
  51
  52         m->holdoff_timeout_usec = 30 * USEC_PER_SEC;
  53
  54         m->idle_action_usec = 30 * USEC_PER_MINUTE;
  55         m->idle_action = HANDLE_IGNORE;
  56
  57         m->runtime_dir_size = physical_memory_scale(10U, 100U); /* 10% */
  58         m->user_tasks_max = system_tasks_max_scale(DEFAULT_USER_TASKS_MAX_PERCENTAGE, 100U); /* 33% */
  59         m->sessions_max = 8192;
  60         m->inhibitors_max = 8192;
  61
  62         m->kill_user_processes = KILL_USER_PROCESSES;
  63
  64         m->kill_only_users = strv_free(m->kill_only_users);
  65         m->kill_exclude_users = strv_free(m->kill_exclude_users);
  66 }
  67
  68 int manager_parse_config_file(Manager *m) {
  69         assert(m);
  70
  71         return config_parse_many_nulstr(PKGSYSCONFDIR "/logind.conf",
  72                                         CONF_PATHS_NULSTR("systemd/logind.conf.d"),
  73                                         "Login\0",
  74                                         config_item_perf_lookup, logind_gperf_lookup,
  75                                         CONFIG_PARSE_WARN, m);
  76 }
  77
  78 int manager_add_device(Manager *m, const char *sysfs, bool master, Device **ret_device) {
  79         Device *d;
  80
  81         assert(m);
  82         assert(sysfs);
  83
  84         d = hashmap_get(m->devices, sysfs);
  85         if (d)
  86                 /* we support adding master-flags, but not removing them */
  87                 d->master = d->master || master;
  88         else {
  89                 d = device_new(m, sysfs, master);
  90                 if (!d)
  91                         return -ENOMEM;
  92         }
  93
  94         if (ret_device)
  95                 *ret_device = d;
  96
  97         return 0;
  98 }
  99
 100 int manager_add_seat(Manager *m, const char *id, Seat **ret_seat) {
 101         Seat *s;
 102         int r;
 103
 104         assert(m);
 105         assert(id);
 106
 107         s = hashmap_get(m->seats, id);
 108         if (!s) {
 109                 r = seat_new(&s, m, id);
 110                 if (r < 0)
 111                         return r;
 112         }
 113
 114         if (ret_seat)
 115                 *ret_seat = s;
 116
 117         return 0;
 118 }
 119
 120 int manager_add_session(Manager *m, const char *id, Session **ret_session) {
 121         Session *s;
 122         int r;
 123
 124         assert(m);
 125         assert(id);
 126
 127         s = hashmap_get(m->sessions, id);
 128         if (!s) {
 129                 r = session_new(&s, m, id);
 130                 if (r < 0)
 131                         return r;
 132         }
 133
 134         if (ret_session)
 135                 *ret_session = s;
 136
 137         return 0;
 138 }
 139
 140 int manager_add_user(
 141                 Manager *m,
 142                 uid_t uid,
 143                 gid_t gid,
 144                 const char *name,
 145                 const char *home,
 146                 User **ret_user) {
 147
 148         User *u;
 149         int r;
 150
 151         assert(m);
 152         assert(name);
 153
 154         u = hashmap_get(m->users, UID_TO_PTR(uid));
 155         if (!u) {
 156                 r = user_new(&u, m, uid, gid, name, home);
 157                 if (r < 0)
 158                         return r;
 159         }
 160
 161         if (ret_user)
 162                 *ret_user = u;
 163
 164         return 0;
 165 }
 166
 167 int manager_add_user_by_name(
 168                 Manager *m,
 169                 const char *name,
 170                 User **ret_user) {
 171
 172         const char *home = NULL;
 173         uid_t uid;
 174         gid_t gid;
 175         int r;
 176
 177         assert(m);
 178         assert(name);
 179
 180         r = get_user_creds(&name, &uid, &gid, &home, NULL, 0);
 181         if (r < 0)
 182                 return r;
 183
 184         return manager_add_user(m, uid, gid, name, home, ret_user);
 185 }
 186
 187 int manager_add_user_by_uid(Manager *m, uid_t uid, User **ret_user) {
 188         struct passwd *p;
 189
 190         assert(m);
 191
 192         errno = 0;
 193         p = getpwuid(uid);
 194         if (!p)
 195                 return errno_or_else(ENOENT);
 196
 197         return manager_add_user(m, uid, p->pw_gid, p->pw_name, p->pw_dir, ret_user);
 198 }
 199
 200 int manager_add_inhibitor(Manager *m, const char* id, Inhibitor **ret) {
 201         Inhibitor *i;
 202         int r;
 203
 204         assert(m);
 205         assert(id);
 206
 207         i = hashmap_get(m->inhibitors, id);
 208         if (!i) {
 209                 r = inhibitor_new(&i, m, id);
 210                 if (r < 0)
 211                         return r;
 212         }
 213
 214         if (ret)
 215                 *ret = i;
 216
 217         return 0;
 218 }
 219
 220 int manager_add_button(Manager *m, const char *name, Button **ret_button) {
 221         Button *b;
 222
 223         assert(m);
 224         assert(name);
 225
 226         b = hashmap_get(m->buttons, name);
 227         if (!b) {
 228                 b = button_new(m, name);
 229                 if (!b)
 230                         return -ENOMEM;
 231         }
 232
 233         if (ret_button)
 234                 *ret_button = b;
 235
 236         return 0;
 237 }
 238
 239 int manager_process_seat_device(Manager *m, sd_device *d) {
 240         Device *device;
 241         int r;
 242
 243         assert(m);
 244
 245         if (device_for_action(d, DEVICE_ACTION_REMOVE)) {
 246                 const char *syspath;
 247
 248                 r = sd_device_get_syspath(d, &syspath);
 249                 if (r < 0)
 250                         return 0;
 251
 252                 device = hashmap_get(m->devices, syspath);
 253                 if (!device)
 254                         return 0;
 255
 256                 seat_add_to_gc_queue(device->seat);
 257                 device_free(device);
 258
 259         } else {
 260                 const char *sn, *syspath;
 261                 bool master;
 262                 Seat *seat;
 263
 264                 if (sd_device_get_property_value(d, "ID_SEAT", &sn) < 0 || isempty(sn))
 265                         sn = "seat0";
 266
 267                 if (!seat_name_is_valid(sn)) {
 268                         log_device_warning(d, "Device with invalid seat name %s found, ignoring.", sn);
 269                         return 0;
 270                 }
 271
 272                 seat = hashmap_get(m->seats, sn);
 273                 master = sd_device_has_tag(d, "master-of-seat") > 0;
 274
 275                 /* Ignore non-master devices for unknown seats */
 276                 if (!master && !seat)
 277                         return 0;
 278
 279                 r = sd_device_get_syspath(d, &syspath);
 280                 if (r < 0)
 281                         return r;
 282
 283                 r = manager_add_device(m, syspath, master, &device);
 284                 if (r < 0)
 285                         return r;
 286
 287                 if (!seat) {
 288                         r = manager_add_seat(m, sn, &seat);
 289                         if (r < 0) {
 290                                 if (!device->seat)
 291                                         device_free(device);
 292
 293                                 return r;
 294                         }
 295                 }
 296
 297                 device_attach(device, seat);
 298                 seat_start(seat);
 299         }
 300
 301         return 0;
 302 }
 303
 304 int manager_process_button_device(Manager *m, sd_device *d) {
 305         const char *sysname;
 306         Button *b;
 307         int r;
 308
 309         assert(m);
 310
 311         r = sd_device_get_sysname(d, &sysname);
 312         if (r < 0)
 313                 return r;
 314
 315         if (device_for_action(d, DEVICE_ACTION_REMOVE)) {
 316
 317                 b = hashmap_get(m->buttons, sysname);
 318                 if (!b)
 319                         return 0;
 320
 321                 button_free(b);
 322
 323         } else {
 324                 const char *sn;
 325
 326                 r = manager_add_button(m, sysname, &b);
 327                 if (r < 0)
 328                         return r;
 329
 330                 if (sd_device_get_property_value(d, "ID_SEAT", &sn) < 0 || isempty(sn))
 331                         sn = "seat0";
 332
 333                 button_set_seat(b, sn);
 334
 335                 r = button_open(b);
 336                 if (r < 0) /* event device doesn't have any keys or switches relevant to us? (or any other error
 337                             * opening the device?) let's close the button again. */
 338                         button_free(b);
 339         }
 340
 341         return 0;
 342 }
 343
 344 int manager_get_session_by_pid(Manager *m, pid_t pid, Session **ret) {
 345         _cleanup_free_ char *unit = NULL;
 346         Session *s;
 347         int r;
 348
 349         assert(m);
 350
 351         if (!pid_is_valid(pid))
 352                 return -EINVAL;
 353
 354         s = hashmap_get(m->sessions_by_leader, PID_TO_PTR(pid));
 355         if (!s) {
 356                 r = cg_pid_get_unit(pid, &unit);
 357                 if (r >= 0)
 358                         s = hashmap_get(m->session_units, unit);
 359         }
 360
 361         if (ret)
 362                 *ret = s;
 363
 364         return !!s;
 365 }
 366
 367 int manager_get_user_by_pid(Manager *m, pid_t pid, User **ret) {
 368         _cleanup_free_ char *unit = NULL;
 369         User *u = NULL;
 370         int r;
 371
 372         assert(m);
 373
 374         if (!pid_is_valid(pid))
 375                 return -EINVAL;
 376
 377         r = cg_pid_get_slice(pid, &unit);
 378         if (r >= 0)
 379                 u = hashmap_get(m->user_units, unit);
 380
 381         if (ret)
 382                 *ret = u;
 383
 384         return !!u;
 385 }
 386
 387 int manager_get_idle_hint(Manager *m, dual_timestamp *t) {
 388         Session *s;
 389         bool idle_hint;
 390         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 391         Iterator i;
 392
 393         assert(m);
 394
 395         idle_hint = !manager_is_inhibited(m, INHIBIT_IDLE, INHIBIT_BLOCK, t, false, false, 0, NULL);
 396
 397         HASHMAP_FOREACH(s, m->sessions, i) {
 398                 dual_timestamp k;
 399                 int ih;
 400
 401                 ih = session_get_idle_hint(s, &k);
 402                 if (ih < 0)
 403                         return ih;
 404
 405                 if (!ih) {
 406                         if (!idle_hint) {
 407                                 if (k.monotonic < ts.monotonic)
 408                                         ts = k;
 409                         } else {
 410                                 idle_hint = false;
 411                                 ts = k;
 412                         }
 413                 } else if (idle_hint) {
 414
 415                         if (k.monotonic > ts.monotonic)
 416                                 ts = k;
 417                 }
 418         }
 419
 420         if (t)
 421                 *t = ts;
 422
 423         return idle_hint;
 424 }
 425
 426 bool manager_shall_kill(Manager *m, const char *user) {
 427         assert(m);
 428         assert(user);
 429
 430         if (!m->kill_exclude_users && streq(user, "root"))
 431                 return false;
 432
 433         if (strv_contains(m->kill_exclude_users, user))
 434                 return false;
 435
 436         if (!strv_isempty(m->kill_only_users))
 437                 return strv_contains(m->kill_only_users, user);
 438
 439         return m->kill_user_processes;
 440 }
 441
 442 int config_parse_n_autovts(
 443                 const char *unit,
 444                 const char *filename,
 445                 unsigned line,
 446                 const char *section,
 447                 unsigned section_line,
 448                 const char *lvalue,
 449                 int ltype,
 450                 const char *rvalue,
 451                 void *data,
 452                 void *userdata) {
 453
 454         unsigned *n = data;
 455         unsigned o;
 456         int r;
 457
 458         assert(filename);
 459         assert(lvalue);
 460         assert(rvalue);
 461         assert(data);
 462
 463         r = safe_atou(rvalue, &o);
 464         if (r < 0) {
 465                 log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse number of autovts, ignoring: %s", rvalue);
 466                 return 0;
 467         }
 468
 469         if (o > 15) {
 470                 log_syntax(unit, LOG_ERR, filename, line, r, "A maximum of 15 autovts are supported, ignoring: %s", rvalue);
 471                 return 0;
 472         }
 473
 474         *n = o;
 475         return 0;
 476 }
 477
 478 static int vt_is_busy(unsigned vtnr) {
 479         struct vt_stat vt_stat;
 480         int r = 0;
 481         _cleanup_close_ int fd;
 482
 483         assert(vtnr >= 1);
 484
 485         /* VT_GETSTATE "cannot return state for more than 16 VTs, since v_state is short" */
 486         assert(vtnr <= 15);
 487
 488         /* We explicitly open /dev/tty1 here instead of /dev/tty0. If
 489          * we'd open the latter we'd open the foreground tty which
 490          * hence would be unconditionally busy. By opening /dev/tty1
 491          * we avoid this. Since tty1 is special and needs to be an
 492          * explicitly loaded getty or DM this is safe. */
 493
 494         fd = open_terminal("/dev/tty1", O_RDWR|O_NOCTTY|O_CLOEXEC);
 495         if (fd < 0)
 496                 return -errno;
 497
 498         if (ioctl(fd, VT_GETSTATE, &vt_stat) < 0)
 499                 r = -errno;
 500         else
 501                 r = !!(vt_stat.v_state & (1 << vtnr));
 502
 503         return r;
 504 }
 505
 506 int manager_spawn_autovt(Manager *m, unsigned vtnr) {
 507         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 508         char name[sizeof("autovt@tty.service") + DECIMAL_STR_MAX(unsigned)];
 509         int r;
 510
 511         assert(m);
 512         assert(vtnr >= 1);
 513
 514         if (vtnr > m->n_autovts &&
 515             vtnr != m->reserve_vt)
 516                 return 0;
 517
 518         if (vtnr != m->reserve_vt) {
 519                 /* If this is the reserved TTY, we'll start the getty
 520                  * on it in any case, but otherwise only if it is not
 521                  * busy. */
 522
 523                 r = vt_is_busy(vtnr);
 524                 if (r < 0)
 525                         return r;
 526                 else if (r > 0)
 527                         return -EBUSY;
 528         }
 529
 530         snprintf(name, sizeof(name), "autovt@tty%u.service", vtnr);
 531         r = sd_bus_call_method(
 532                         m->bus,
 533                         "org.freedesktop.systemd1",
 534                         "/org/freedesktop/systemd1",
 535                         "org.freedesktop.systemd1.Manager",
 536                         "StartUnit",
 537                         &error,
 538                         NULL,
 539                         "ss", name, "fail");
 540         if (r < 0)
 541                 return log_error_errno(r, "Failed to start %s: %s", name, bus_error_message(&error, r));
 542
 543         return 0;
 544 }
 545
 546 bool manager_is_lid_closed(Manager *m) {
 547         Iterator i;
 548         Button *b;
 549
 550         HASHMAP_FOREACH(b, m->buttons, i)
 551                 if (b->lid_closed)
 552                         return true;
 553
 554         return false;
 555 }
 556
 557 static bool manager_is_docked(Manager *m) {
 558         Iterator i;
 559         Button *b;
 560
 561         HASHMAP_FOREACH(b, m->buttons, i)
 562                 if (b->docked)
 563                         return true;
 564
 565         return false;
 566 }
 567
 568 static int manager_count_external_displays(Manager *m) {
 569         _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
 570         sd_device *d;
 571         int r, n = 0;
 572
 573         r = sd_device_enumerator_new(&e);
 574         if (r < 0)
 575                 return r;
 576
 577         r = sd_device_enumerator_allow_uninitialized(e);
 578         if (r < 0)
 579                 return r;
 580
 581         r = sd_device_enumerator_add_match_subsystem(e, "drm", true);
 582         if (r < 0)
 583                 return r;
 584
 585         FOREACH_DEVICE(e, d) {
 586                 const char *status, *enabled, *dash, *nn, *subsys;
 587                 sd_device *p;
 588
 589                 if (sd_device_get_parent(d, &p) < 0)
 590                         continue;
 591
 592                 /* If the parent shares the same subsystem as the
 593                  * device we are looking at then it is a connector,
 594                  * which is what we are interested in. */
 595                 if (sd_device_get_subsystem(p, &subsys) < 0 || !streq(subsys, "drm"))
 596                         continue;
 597
 598                 if (sd_device_get_sysname(d, &nn) < 0)
 599                         continue;
 600
 601                 /* Ignore internal displays: the type is encoded in the sysfs name, as the second dash separated item
 602                  * (the first is the card name, the last the connector number). We implement a blacklist of external
 603                  * displays here, rather than a whitelist of internal ones, to ensure we don't block suspends too
 604                  * eagerly. */
 605                 dash = strchr(nn, '-');
 606                 if (!dash)
 607                         continue;
 608
 609                 dash++;
 610                 if (!STARTSWITH_SET(dash,
 611                                     "VGA-", "DVI-I-", "DVI-D-", "DVI-A-"
 612                                     "Composite-", "SVIDEO-", "Component-",
 613                                     "DIN-", "DP-", "HDMI-A-", "HDMI-B-", "TV-"))
 614                         continue;
 615
 616                 /* Ignore ports that are not enabled */
 617                 if (sd_device_get_sysattr_value(d, "enabled", &enabled) < 0 || !streq(enabled, "enabled"))
 618                         continue;
 619
 620                 /* We count any connector which is not explicitly
 621                  * "disconnected" as connected. */
 622                 if (sd_device_get_sysattr_value(d, "status", &status) < 0 || !streq(status, "disconnected"))
 623                         n++;
 624         }
 625
 626         return n;
 627 }
 628
 629 bool manager_is_docked_or_external_displays(Manager *m) {
 630         int n;
 631
 632         /* If we are docked don't react to lid closing */
 633         if (manager_is_docked(m)) {
 634                 log_debug("System is docked.");
 635                 return true;
 636         }
 637
 638         /* If we have more than one display connected,
 639          * assume that we are docked. */
 640         n = manager_count_external_displays(m);
 641         if (n < 0)
 642                 log_warning_errno(n, "Display counting failed: %m");
 643         else if (n >= 1) {
 644                 log_debug("External (%i) displays connected.", n);
 645                 return true;
 646         }
 647
 648         return false;
 649 }
 650
 651 bool manager_is_on_external_power(void) {
 652         int r;
 653
 654         /* For now we only check for AC power, but 'external power' can apply to anything that isn't an internal
 655          * battery */
 656         r = on_ac_power();
 657         if (r < 0)
 658                 log_warning_errno(r, "Failed to read AC power status: %m");
 659
 660         return r != 0; /* Treat failure as 'on AC' */
 661 }
 662
 663 bool manager_all_buttons_ignored(Manager *m) {
 664         assert(m);
 665
 666         if (m->handle_power_key != HANDLE_IGNORE)
 667                 return false;
 668         if (m->handle_suspend_key != HANDLE_IGNORE)
 669                 return false;
 670         if (m->handle_hibernate_key != HANDLE_IGNORE)
 671                 return false;
 672         if (m->handle_lid_switch != HANDLE_IGNORE)
 673                 return false;
 674         if (!IN_SET(m->handle_lid_switch_ep, _HANDLE_ACTION_INVALID, HANDLE_IGNORE))
 675                 return false;
 676         if (m->handle_lid_switch_docked != HANDLE_IGNORE)
 677                 return false;
 678
 679         return true;
 680 }
 681
 682 int manager_read_utmp(Manager *m) {
 683 #if ENABLE_UTMP
 684         int r;
 685
 686         assert(m);
 687
 688         if (utmpxname(_PATH_UTMPX) < 0)
 689                 return log_error_errno(errno, "Failed to set utmp path to " _PATH_UTMPX ": %m");
 690
 691         setutxent();
 692
 693         for (;;) {
 694                 _cleanup_free_ char *t = NULL;
 695                 struct utmpx *u;
 696                 const char *c;
 697                 Session *s;
 698
 699                 errno = 0;
 700                 u = getutxent();
 701                 if (!u) {
 702                         if (errno != 0)
 703                                 log_warning_errno(errno, "Failed to read " _PATH_UTMPX ", ignoring: %m");
 704                         r = 0;
 705                         break;
 706                 }
 707
 708                 if (u->ut_type != USER_PROCESS)
 709                         continue;
 710
 711                 if (!pid_is_valid(u->ut_pid))
 712                         continue;
 713
 714                 t = strndup(u->ut_line, sizeof(u->ut_line));
 715                 if (!t) {
 716                         r = log_oom();
 717                         break;
 718                 }
 719
 720                 c = path_startswith(t, "/dev/");
 721                 if (c) {
 722                         r = free_and_strdup(&t, c);
 723                         if (r < 0) {
 724                                 log_oom();
 725                                 break;
 726                         }
 727                 }
 728
 729                 if (isempty(t))
 730                         continue;
 731
 732                 s = hashmap_get(m->sessions_by_leader, PID_TO_PTR(u->ut_pid));
 733                 if (!s)
 734                         continue;
 735
 736                 if (s->tty_validity == TTY_FROM_UTMP && !streq_ptr(s->tty, t)) {
 737                         /* This may happen on multiplexed SSH connection (i.e. 'SSH connection sharing'). In
 738                          * this case PAM and utmp sessions don't match. In such a case let's invalidate the TTY
 739                          * information and never acquire it again. */
 740
 741                         s->tty = mfree(s->tty);
 742                         s->tty_validity = TTY_UTMP_INCONSISTENT;
 743                         log_debug("Session '%s' has inconsistent TTY information, dropping TTY information.", s->id);
 744                         continue;
 745                 }
 746
 747                 /* Never override what we figured out once */
 748                 if (s->tty || s->tty_validity >= 0)
 749                         continue;
 750
 751                 s->tty = TAKE_PTR(t);
 752                 s->tty_validity = TTY_FROM_UTMP;
 753                 log_debug("Acquired TTY information '%s' from utmp for session '%s'.", s->tty, s->id);
 754         }
 755
 756         endutxent();
 757         return r;
 758 #else
 759         return 0;
 760 #endif
 761 }
 762
 763 #if ENABLE_UTMP
 764 static int manager_dispatch_utmp(sd_event_source *s, const struct inotify_event *event, void *userdata) {
 765         Manager *m = userdata;
 766
 767         assert(m);
 768
 769         /* If there's indication the file itself might have been removed or became otherwise unavailable, then let's
 770          * reestablish the watch on whatever there's now. */
 771         if ((event->mask & (IN_ATTRIB|IN_DELETE_SELF|IN_MOVE_SELF|IN_Q_OVERFLOW|IN_UNMOUNT)) != 0)
 772                 manager_connect_utmp(m);
 773
 774         (void) manager_read_utmp(m);
 775         return 0;
 776 }
 777 #endif
 778
 779 void manager_connect_utmp(Manager *m) {
 780 #if ENABLE_UTMP
 781         sd_event_source *s = NULL;
 782         int r;
 783
 784         assert(m);
 785
 786         /* Watch utmp for changes via inotify. We do this to deal with tools such as ssh, which will register the PAM
 787          * session early, and acquire a TTY only much later for the connection. Thus during PAM the TTY won't be known
 788          * yet. ssh will register itself with utmp when it finally acquired the TTY. Hence, let's make use of this, and
 789          * watch utmp for the TTY asynchronously. We use the PAM session's leader PID as key, to find the right entry.
 790          *
 791          * Yes, relying on utmp is pretty ugly, but it's good enough for informational purposes, as well as idle
 792          * detection (which, for tty sessions, relies on the TTY used) */
 793
 794         r = sd_event_add_inotify(m->event, &s, _PATH_UTMPX, IN_MODIFY|IN_MOVE_SELF|IN_DELETE_SELF|IN_ATTRIB, manager_dispatch_utmp, m);
 795         if (r < 0)
 796                 log_full_errno(r == -ENOENT ? LOG_DEBUG: LOG_WARNING, r, "Failed to create inotify watch on " _PATH_UTMPX ", ignoring: %m");
 797         else {
 798                 r = sd_event_source_set_priority(s, SD_EVENT_PRIORITY_IDLE);
 799                 if (r < 0)
 800                         log_warning_errno(r, "Failed to adjust utmp event source priority, ignoring: %m");
 801
 802                 (void) sd_event_source_set_description(s, "utmp");
 803         }
 804
 805         sd_event_source_unref(m->utmp_event_source);
 806         m->utmp_event_source = s;
 807 #endif
 808 }
 809
 810 void manager_reconnect_utmp(Manager *m) {
 811 #if ENABLE_UTMP
 812         assert(m);
 813
 814         if (m->utmp_event_source)
 815                 return;
 816
 817         manager_connect_utmp(m);
 818 #endif
 819 }