src/login/logind-user.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2011 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <string.h>
  22 #include <sys/mount.h>
  23 #include <unistd.h>
  24
  25 #include "alloc-util.h"
  26 #include "bus-common-errors.h"
  27 #include "bus-error.h"
  28 #include "bus-util.h"
  29 #include "cgroup-util.h"
  30 #include "clean-ipc.h"
  31 #include "conf-parser.h"
  32 #include "escape.h"
  33 #include "fd-util.h"
  34 #include "fileio.h"
  35 #include "format-util.h"
  36 #include "fs-util.h"
  37 #include "hashmap.h"
  38 #include "label.h"
  39 #include "logind-user.h"
  40 #include "mkdir.h"
  41 #include "mount-util.h"
  42 #include "parse-util.h"
  43 #include "path-util.h"
  44 #include "rm-rf.h"
  45 #include "smack-util.h"
  46 #include "special.h"
  47 #include "stdio-util.h"
  48 #include "string-table.h"
  49 #include "unit-name.h"
  50 #include "user-util.h"
  51 #include "util.h"
  52
  53 int user_new(User **out, Manager *m, uid_t uid, gid_t gid, const char *name) {
  54         _cleanup_(user_freep) User *u = NULL;
  55         char lu[DECIMAL_STR_MAX(uid_t) + 1];
  56         int r;
  57
  58         assert(out);
  59         assert(m);
  60         assert(name);
  61
  62         u = new0(User, 1);
  63         if (!u)
  64                 return -ENOMEM;
  65
  66         u->manager = m;
  67         u->uid = uid;
  68         u->gid = gid;
  69         xsprintf(lu, UID_FMT, uid);
  70
  71         u->name = strdup(name);
  72         if (!u->name)
  73                 return -ENOMEM;
  74
  75         if (asprintf(&u->state_file, "/run/systemd/users/"UID_FMT, uid) < 0)
  76                 return -ENOMEM;
  77
  78         if (asprintf(&u->runtime_path, "/run/user/"UID_FMT, uid) < 0)
  79                 return -ENOMEM;
  80
  81         r = slice_build_subslice(SPECIAL_USER_SLICE, lu, &u->slice);
  82         if (r < 0)
  83                 return r;
  84
  85         r = unit_name_build("user", lu, ".service", &u->service);
  86         if (r < 0)
  87                 return r;
  88
  89         r = hashmap_put(m->users, UID_TO_PTR(uid), u);
  90         if (r < 0)
  91                 return r;
  92
  93         r = hashmap_put(m->user_units, u->slice, u);
  94         if (r < 0)
  95                 return r;
  96
  97         r = hashmap_put(m->user_units, u->service, u);
  98         if (r < 0)
  99                 return r;
 100
 101         *out = u;
 102         u = NULL;
 103         return 0;
 104 }
 105
 106 User *user_free(User *u) {
 107         if (!u)
 108                 return NULL;
 109
 110         if (u->in_gc_queue)
 111                 LIST_REMOVE(gc_queue, u->manager->user_gc_queue, u);
 112
 113         while (u->sessions)
 114                 session_free(u->sessions);
 115
 116         if (u->service)
 117                 hashmap_remove_value(u->manager->user_units, u->service, u);
 118
 119         if (u->slice)
 120                 hashmap_remove_value(u->manager->user_units, u->slice, u);
 121
 122         hashmap_remove_value(u->manager->users, UID_TO_PTR(u->uid), u);
 123
 124         u->slice_job = mfree(u->slice_job);
 125         u->service_job = mfree(u->service_job);
 126
 127         u->service = mfree(u->service);
 128         u->slice = mfree(u->slice);
 129         u->runtime_path = mfree(u->runtime_path);
 130         u->state_file = mfree(u->state_file);
 131         u->name = mfree(u->name);
 132
 133         return mfree(u);
 134 }
 135
 136 static int user_save_internal(User *u) {
 137         _cleanup_free_ char *temp_path = NULL;
 138         _cleanup_fclose_ FILE *f = NULL;
 139         int r;
 140
 141         assert(u);
 142         assert(u->state_file);
 143
 144         r = mkdir_safe_label("/run/systemd/users", 0755, 0, 0, false);
 145         if (r < 0)
 146                 goto fail;
 147
 148         r = fopen_temporary(u->state_file, &f, &temp_path);
 149         if (r < 0)
 150                 goto fail;
 151
 152         fchmod(fileno(f), 0644);
 153
 154         fprintf(f,
 155                 "# This is private data. Do not parse.\n"
 156                 "NAME=%s\n"
 157                 "STATE=%s\n",
 158                 u->name,
 159                 user_state_to_string(user_get_state(u)));
 160
 161         /* LEGACY: no-one reads RUNTIME= anymore, drop it at some point */
 162         if (u->runtime_path)
 163                 fprintf(f, "RUNTIME=%s\n", u->runtime_path);
 164
 165         if (u->service_job)
 166                 fprintf(f, "SERVICE_JOB=%s\n", u->service_job);
 167
 168         if (u->slice_job)
 169                 fprintf(f, "SLICE_JOB=%s\n", u->slice_job);
 170
 171         if (u->display)
 172                 fprintf(f, "DISPLAY=%s\n", u->display->id);
 173
 174         if (dual_timestamp_is_set(&u->timestamp))
 175                 fprintf(f,
 176                         "REALTIME="USEC_FMT"\n"
 177                         "MONOTONIC="USEC_FMT"\n",
 178                         u->timestamp.realtime,
 179                         u->timestamp.monotonic);
 180
 181         if (u->sessions) {
 182                 Session *i;
 183                 bool first;
 184
 185                 fputs_unlocked("SESSIONS=", f);
 186                 first = true;
 187                 LIST_FOREACH(sessions_by_user, i, u->sessions) {
 188                         if (first)
 189                                 first = false;
 190                         else
 191                                 fputc_unlocked(' ', f);
 192
 193                         fputs_unlocked(i->id, f);
 194                 }
 195
 196                 fputs_unlocked("\nSEATS=", f);
 197                 first = true;
 198                 LIST_FOREACH(sessions_by_user, i, u->sessions) {
 199                         if (!i->seat)
 200                                 continue;
 201
 202                         if (first)
 203                                 first = false;
 204                         else
 205                                 fputc_unlocked(' ', f);
 206
 207                         fputs_unlocked(i->seat->id, f);
 208                 }
 209
 210                 fputs_unlocked("\nACTIVE_SESSIONS=", f);
 211                 first = true;
 212                 LIST_FOREACH(sessions_by_user, i, u->sessions) {
 213                         if (!session_is_active(i))
 214                                 continue;
 215
 216                         if (first)
 217                                 first = false;
 218                         else
 219                                 fputc_unlocked(' ', f);
 220
 221                         fputs_unlocked(i->id, f);
 222                 }
 223
 224                 fputs_unlocked("\nONLINE_SESSIONS=", f);
 225                 first = true;
 226                 LIST_FOREACH(sessions_by_user, i, u->sessions) {
 227                         if (session_get_state(i) == SESSION_CLOSING)
 228                                 continue;
 229
 230                         if (first)
 231                                 first = false;
 232                         else
 233                                 fputc_unlocked(' ', f);
 234
 235                         fputs_unlocked(i->id, f);
 236                 }
 237
 238                 fputs_unlocked("\nACTIVE_SEATS=", f);
 239                 first = true;
 240                 LIST_FOREACH(sessions_by_user, i, u->sessions) {
 241                         if (!session_is_active(i) || !i->seat)
 242                                 continue;
 243
 244                         if (first)
 245                                 first = false;
 246                         else
 247                                 fputc_unlocked(' ', f);
 248
 249                         fputs_unlocked(i->seat->id, f);
 250                 }
 251
 252                 fputs_unlocked("\nONLINE_SEATS=", f);
 253                 first = true;
 254                 LIST_FOREACH(sessions_by_user, i, u->sessions) {
 255                         if (session_get_state(i) == SESSION_CLOSING || !i->seat)
 256                                 continue;
 257
 258                         if (first)
 259                                 first = false;
 260                         else
 261                                 fputc_unlocked(' ', f);
 262
 263                         fputs_unlocked(i->seat->id, f);
 264                 }
 265                 fputc_unlocked('\n', f);
 266         }
 267
 268         r = fflush_and_check(f);
 269         if (r < 0)
 270                 goto fail;
 271
 272         if (rename(temp_path, u->state_file) < 0) {
 273                 r = -errno;
 274                 goto fail;
 275         }
 276
 277         return 0;
 278
 279 fail:
 280         (void) unlink(u->state_file);
 281
 282         if (temp_path)
 283                 (void) unlink(temp_path);
 284
 285         return log_error_errno(r, "Failed to save user data %s: %m", u->state_file);
 286 }
 287
 288 int user_save(User *u) {
 289         assert(u);
 290
 291         if (!u->started)
 292                 return 0;
 293
 294         return user_save_internal (u);
 295 }
 296
 297 int user_load(User *u) {
 298         _cleanup_free_ char *display = NULL, *realtime = NULL, *monotonic = NULL;
 299         Session *s = NULL;
 300         int r;
 301
 302         assert(u);
 303
 304         r = parse_env_file(u->state_file, NEWLINE,
 305                            "SERVICE_JOB", &u->service_job,
 306                            "SLICE_JOB",   &u->slice_job,
 307                            "DISPLAY",     &display,
 308                            "REALTIME",    &realtime,
 309                            "MONOTONIC",   &monotonic,
 310                            NULL);
 311         if (r < 0) {
 312                 if (r == -ENOENT)
 313                         return 0;
 314
 315                 return log_error_errno(r, "Failed to read %s: %m", u->state_file);
 316         }
 317
 318         if (display)
 319                 s = hashmap_get(u->manager->sessions, display);
 320
 321         if (s && s->display && display_is_local(s->display))
 322                 u->display = s;
 323
 324         if (realtime)
 325                 timestamp_deserialize(realtime, &u->timestamp.realtime);
 326         if (monotonic)
 327                 timestamp_deserialize(monotonic, &u->timestamp.monotonic);
 328
 329         return r;
 330 }
 331
 332 static int user_mkdir_runtime_path(User *u) {
 333         int r;
 334
 335         assert(u);
 336
 337         r = mkdir_safe_label("/run/user", 0755, 0, 0, false);
 338         if (r < 0)
 339                 return log_error_errno(r, "Failed to create /run/user: %m");
 340
 341         if (path_is_mount_point(u->runtime_path, NULL, 0) <= 0) {
 342                 _cleanup_free_ char *t = NULL;
 343
 344                 (void) mkdir_label(u->runtime_path, 0700);
 345
 346                 if (mac_smack_use())
 347                         r = asprintf(&t, "mode=0700,smackfsroot=*,uid=" UID_FMT ",gid=" GID_FMT ",size=%zu", u->uid, u->gid, u->manager->runtime_dir_size);
 348                 else
 349                         r = asprintf(&t, "mode=0700,uid=" UID_FMT ",gid=" GID_FMT ",size=%zu", u->uid, u->gid, u->manager->runtime_dir_size);
 350                 if (r < 0) {
 351                         r = log_oom();
 352                         goto fail;
 353                 }
 354
 355                 r = mount("tmpfs", u->runtime_path, "tmpfs", MS_NODEV|MS_NOSUID, t);
 356                 if (r < 0) {
 357                         if (!IN_SET(errno, EPERM, EACCES)) {
 358                                 r = log_error_errno(errno, "Failed to mount per-user tmpfs directory %s: %m", u->runtime_path);
 359                                 goto fail;
 360                         }
 361
 362                         log_debug_errno(errno, "Failed to mount per-user tmpfs directory %s, assuming containerized execution, ignoring: %m", u->runtime_path);
 363
 364                         r = chmod_and_chown(u->runtime_path, 0700, u->uid, u->gid);
 365                         if (r < 0) {
 366                                 log_error_errno(r, "Failed to change runtime directory ownership and mode: %m");
 367                                 goto fail;
 368                         }
 369                 }
 370
 371                 r = label_fix(u->runtime_path, false, false);
 372                 if (r < 0)
 373                         log_warning_errno(r, "Failed to fix label of '%s', ignoring: %m", u->runtime_path);
 374         }
 375
 376         return 0;
 377
 378 fail:
 379         /* Try to clean up, but ignore errors */
 380         (void) rmdir(u->runtime_path);
 381         return r;
 382 }
 383
 384 static int user_start_slice(User *u) {
 385         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 386         const char *description;
 387         char *job;
 388         int r;
 389
 390         assert(u);
 391
 392         u->slice_job = mfree(u->slice_job);
 393         description = strjoina("User Slice of ", u->name);
 394
 395         r = manager_start_slice(
 396                         u->manager,
 397                         u->slice,
 398                         description,
 399                         "systemd-logind.service",
 400                         "systemd-user-sessions.service",
 401                         u->manager->user_tasks_max,
 402                         &error,
 403                         &job);
 404         if (r >= 0)
 405                 u->slice_job = job;
 406         else if (!sd_bus_error_has_name(&error, BUS_ERROR_UNIT_EXISTS))
 407                 /* we don't fail due to this, let's try to continue */
 408                 log_error_errno(r, "Failed to start user slice %s, ignoring: %s (%s)",
 409                                 u->slice, bus_error_message(&error, r), error.name);
 410
 411         return 0;
 412 }
 413
 414 static int user_start_service(User *u) {
 415         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 416         char *job;
 417         int r;
 418
 419         assert(u);
 420
 421         u->service_job = mfree(u->service_job);
 422
 423         r = manager_start_unit(
 424                         u->manager,
 425                         u->service,
 426                         &error,
 427                         &job);
 428         if (r < 0)
 429                 /* we don't fail due to this, let's try to continue */
 430                 log_error_errno(r, "Failed to start user service, ignoring: %s", bus_error_message(&error, r));
 431         else
 432                 u->service_job = job;
 433
 434         return 0;
 435 }
 436
 437 int user_start(User *u) {
 438         int r;
 439
 440         assert(u);
 441
 442         if (u->started && !u->stopping)
 443                 return 0;
 444
 445         /*
 446          * If u->stopping is set, the user is marked for removal and the slice
 447          * and service stop-jobs are queued. We have to clear that flag before
 448          * queing the start-jobs again. If they succeed, the user object can be
 449          * re-used just fine (pid1 takes care of job-ordering and proper
 450          * restart), but if they fail, we want to force another user_stop() so
 451          * possibly pending units are stopped.
 452          * Note that we don't clear u->started, as we have no clue what state
 453          * the user is in on failure here. Hence, we pretend the user is
 454          * running so it will be properly taken down by GC. However, we clearly
 455          * return an error from user_start() in that case, so no further
 456          * reference to the user is taken.
 457          */
 458         u->stopping = false;
 459
 460         if (!u->started) {
 461                 log_debug("New user %s logged in.", u->name);
 462
 463                 /* Make XDG_RUNTIME_DIR */
 464                 r = user_mkdir_runtime_path(u);
 465                 if (r < 0)
 466                         return r;
 467         }
 468
 469         /* Create cgroup */
 470         r = user_start_slice(u);
 471         if (r < 0)
 472                 return r;
 473
 474         /* Save the user data so far, because pam_systemd will read the
 475          * XDG_RUNTIME_DIR out of it while starting up systemd --user.
 476          * We need to do user_save_internal() because we have not
 477          * "officially" started yet. */
 478         user_save_internal(u);
 479
 480         /* Spawn user systemd */
 481         r = user_start_service(u);
 482         if (r < 0)
 483                 return r;
 484
 485         if (!u->started) {
 486                 if (!dual_timestamp_is_set(&u->timestamp))
 487                         dual_timestamp_get(&u->timestamp);
 488                 user_send_signal(u, true);
 489                 u->started = true;
 490         }
 491
 492         /* Save new user data */
 493         user_save(u);
 494
 495         return 0;
 496 }
 497
 498 static int user_stop_slice(User *u) {
 499         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 500         char *job;
 501         int r;
 502
 503         assert(u);
 504
 505         r = manager_stop_unit(u->manager, u->slice, &error, &job);
 506         if (r < 0) {
 507                 log_error("Failed to stop user slice: %s", bus_error_message(&error, r));
 508                 return r;
 509         }
 510
 511         free(u->slice_job);
 512         u->slice_job = job;
 513
 514         return r;
 515 }
 516
 517 static int user_stop_service(User *u) {
 518         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 519         char *job;
 520         int r;
 521
 522         assert(u);
 523
 524         r = manager_stop_unit(u->manager, u->service, &error, &job);
 525         if (r < 0) {
 526                 log_error("Failed to stop user service: %s", bus_error_message(&error, r));
 527                 return r;
 528         }
 529
 530         free(u->service_job);
 531         u->service_job = job;
 532
 533         return r;
 534 }
 535
 536 static int user_remove_runtime_path(User *u) {
 537         int r;
 538
 539         assert(u);
 540
 541         r = rm_rf(u->runtime_path, 0);
 542         if (r < 0)
 543                 log_error_errno(r, "Failed to remove runtime directory %s (before unmounting): %m", u->runtime_path);
 544
 545         /* Ignore cases where the directory isn't mounted, as that's
 546          * quite possible, if we lacked the permissions to mount
 547          * something */
 548         r = umount2(u->runtime_path, MNT_DETACH);
 549         if (r < 0 && !IN_SET(errno, EINVAL, ENOENT))
 550                 log_error_errno(errno, "Failed to unmount user runtime directory %s: %m", u->runtime_path);
 551
 552         r = rm_rf(u->runtime_path, REMOVE_ROOT);
 553         if (r < 0)
 554                 log_error_errno(r, "Failed to remove runtime directory %s (after unmounting): %m", u->runtime_path);
 555
 556         return r;
 557 }
 558
 559 int user_stop(User *u, bool force) {
 560         Session *s;
 561         int r = 0, k;
 562         assert(u);
 563
 564         /* Stop jobs have already been queued */
 565         if (u->stopping) {
 566                 user_save(u);
 567                 return r;
 568         }
 569
 570         LIST_FOREACH(sessions_by_user, s, u->sessions) {
 571                 k = session_stop(s, force);
 572                 if (k < 0)
 573                         r = k;
 574         }
 575
 576         /* Kill systemd */
 577         k = user_stop_service(u);
 578         if (k < 0)
 579                 r = k;
 580
 581         /* Kill cgroup */
 582         k = user_stop_slice(u);
 583         if (k < 0)
 584                 r = k;
 585
 586         u->stopping = true;
 587
 588         user_save(u);
 589
 590         return r;
 591 }
 592
 593 int user_finalize(User *u) {
 594         Session *s;
 595         int r = 0, k;
 596
 597         assert(u);
 598
 599         if (u->started)
 600                 log_debug("User %s logged out.", u->name);
 601
 602         LIST_FOREACH(sessions_by_user, s, u->sessions) {
 603                 k = session_finalize(s);
 604                 if (k < 0)
 605                         r = k;
 606         }
 607
 608         /* Kill XDG_RUNTIME_DIR */
 609         k = user_remove_runtime_path(u);
 610         if (k < 0)
 611                 r = k;
 612
 613         /* Clean SysV + POSIX IPC objects, but only if this is not a system user. Background: in many setups cronjobs
 614          * are run in full PAM and thus logind sessions, even if the code run doesn't belong to actual users but to
 615          * system components. Since enable RemoveIPC= globally for all users, we need to be a bit careful with such
 616          * cases, as we shouldn't accidentally remove a system service's IPC objects while it is running, just because
 617          * a cronjob running as the same user just finished. Hence: exclude system users generally from IPC clean-up,
 618          * and do it only for normal users. */
 619         if (u->manager->remove_ipc && u->uid > SYSTEM_UID_MAX) {
 620                 k = clean_ipc_by_uid(u->uid);
 621                 if (k < 0)
 622                         r = k;
 623         }
 624
 625         unlink(u->state_file);
 626         user_add_to_gc_queue(u);
 627
 628         if (u->started) {
 629                 user_send_signal(u, false);
 630                 u->started = false;
 631         }
 632
 633         return r;
 634 }
 635
 636 int user_get_idle_hint(User *u, dual_timestamp *t) {
 637         Session *s;
 638         bool idle_hint = true;
 639         dual_timestamp ts = DUAL_TIMESTAMP_NULL;
 640
 641         assert(u);
 642
 643         LIST_FOREACH(sessions_by_user, s, u->sessions) {
 644                 dual_timestamp k;
 645                 int ih;
 646
 647                 ih = session_get_idle_hint(s, &k);
 648                 if (ih < 0)
 649                         return ih;
 650
 651                 if (!ih) {
 652                         if (!idle_hint) {
 653                                 if (k.monotonic < ts.monotonic)
 654                                         ts = k;
 655                         } else {
 656                                 idle_hint = false;
 657                                 ts = k;
 658                         }
 659                 } else if (idle_hint) {
 660
 661                         if (k.monotonic > ts.monotonic)
 662                                 ts = k;
 663                 }
 664         }
 665
 666         if (t)
 667                 *t = ts;
 668
 669         return idle_hint;
 670 }
 671
 672 int user_check_linger_file(User *u) {
 673         _cleanup_free_ char *cc = NULL;
 674         char *p = NULL;
 675
 676         cc = cescape(u->name);
 677         if (!cc)
 678                 return -ENOMEM;
 679
 680         p = strjoina("/var/lib/systemd/linger/", cc);
 681
 682         return access(p, F_OK) >= 0;
 683 }
 684
 685 bool user_check_gc(User *u, bool drop_not_started) {
 686         assert(u);
 687
 688         if (drop_not_started && !u->started)
 689                 return false;
 690
 691         if (u->sessions)
 692                 return true;
 693
 694         if (user_check_linger_file(u) > 0)
 695                 return true;
 696
 697         if (u->slice_job && manager_job_is_active(u->manager, u->slice_job))
 698                 return true;
 699
 700         if (u->service_job && manager_job_is_active(u->manager, u->service_job))
 701                 return true;
 702
 703         return false;
 704 }
 705
 706 void user_add_to_gc_queue(User *u) {
 707         assert(u);
 708
 709         if (u->in_gc_queue)
 710                 return;
 711
 712         LIST_PREPEND(gc_queue, u->manager->user_gc_queue, u);
 713         u->in_gc_queue = true;
 714 }
 715
 716 UserState user_get_state(User *u) {
 717         Session *i;
 718
 719         assert(u);
 720
 721         if (u->stopping)
 722                 return USER_CLOSING;
 723
 724         if (!u->started || u->slice_job || u->service_job)
 725                 return USER_OPENING;
 726
 727         if (u->sessions) {
 728                 bool all_closing = true;
 729
 730                 LIST_FOREACH(sessions_by_user, i, u->sessions) {
 731                         SessionState state;
 732
 733                         state = session_get_state(i);
 734                         if (state == SESSION_ACTIVE)
 735                                 return USER_ACTIVE;
 736                         if (state != SESSION_CLOSING)
 737                                 all_closing = false;
 738                 }
 739
 740                 return all_closing ? USER_CLOSING : USER_ONLINE;
 741         }
 742
 743         if (user_check_linger_file(u) > 0)
 744                 return USER_LINGERING;
 745
 746         return USER_CLOSING;
 747 }
 748
 749 int user_kill(User *u, int signo) {
 750         assert(u);
 751
 752         return manager_kill_unit(u->manager, u->slice, KILL_ALL, signo, NULL);
 753 }
 754
 755 static bool elect_display_filter(Session *s) {
 756         /* Return true if the session is a candidate for the user’s ‘primary
 757          * session’ or ‘display’. */
 758         assert(s);
 759
 760         return (s->class == SESSION_USER && !s->stopping);
 761 }
 762
 763 static int elect_display_compare(Session *s1, Session *s2) {
 764         /* Indexed by SessionType. Lower numbers mean more preferred. */
 765         const int type_ranks[_SESSION_TYPE_MAX] = {
 766                 [SESSION_UNSPECIFIED] = 0,
 767                 [SESSION_TTY] = -2,
 768                 [SESSION_X11] = -3,
 769                 [SESSION_WAYLAND] = -3,
 770                 [SESSION_MIR] = -3,
 771                 [SESSION_WEB] = -1,
 772         };
 773
 774         /* Calculate the partial order relationship between s1 and s2,
 775          * returning < 0 if s1 is preferred as the user’s ‘primary session’,
 776          * 0 if s1 and s2 are equally preferred or incomparable, or > 0 if s2
 777          * is preferred.
 778          *
 779          * s1 or s2 may be NULL. */
 780         if (!s1 && !s2)
 781                 return 0;
 782
 783         if ((s1 == NULL) != (s2 == NULL))
 784                 return (s1 == NULL) - (s2 == NULL);
 785
 786         if (s1->stopping != s2->stopping)
 787                 return s1->stopping - s2->stopping;
 788
 789         if ((s1->class != SESSION_USER) != (s2->class != SESSION_USER))
 790                 return (s1->class != SESSION_USER) - (s2->class != SESSION_USER);
 791
 792         if ((s1->type == _SESSION_TYPE_INVALID) != (s2->type == _SESSION_TYPE_INVALID))
 793                 return (s1->type == _SESSION_TYPE_INVALID) - (s2->type == _SESSION_TYPE_INVALID);
 794
 795         if (s1->type != s2->type)
 796                 return type_ranks[s1->type] - type_ranks[s2->type];
 797
 798         return 0;
 799 }
 800
 801 void user_elect_display(User *u) {
 802         Session *s;
 803
 804         assert(u);
 805
 806         /* This elects a primary session for each user, which we call
 807          * the "display". We try to keep the assignment stable, but we
 808          * "upgrade" to better choices. */
 809         log_debug("Electing new display for user %s", u->name);
 810
 811         LIST_FOREACH(sessions_by_user, s, u->sessions) {
 812                 if (!elect_display_filter(s)) {
 813                         log_debug("Ignoring session %s", s->id);
 814                         continue;
 815                 }
 816
 817                 if (elect_display_compare(s, u->display) < 0) {
 818                         log_debug("Choosing session %s in preference to %s", s->id, u->display ? u->display->id : "-");
 819                         u->display = s;
 820                 }
 821         }
 822 }
 823
 824 static const char* const user_state_table[_USER_STATE_MAX] = {
 825         [USER_OFFLINE] = "offline",
 826         [USER_OPENING] = "opening",
 827         [USER_LINGERING] = "lingering",
 828         [USER_ONLINE] = "online",
 829         [USER_ACTIVE] = "active",
 830         [USER_CLOSING] = "closing"
 831 };
 832
 833 DEFINE_STRING_TABLE_LOOKUP(user_state, UserState);
 834
 835 int config_parse_tmpfs_size(
 836                 const char* unit,
 837                 const char *filename,
 838                 unsigned line,
 839                 const char *section,
 840                 unsigned section_line,
 841                 const char *lvalue,
 842                 int ltype,
 843                 const char *rvalue,
 844                 void *data,
 845                 void *userdata) {
 846
 847         size_t *sz = data;
 848         int r;
 849
 850         assert(filename);
 851         assert(lvalue);
 852         assert(rvalue);
 853         assert(data);
 854
 855         /* First, try to parse as percentage */
 856         r = parse_percent(rvalue);
 857         if (r > 0 && r < 100)
 858                 *sz = physical_memory_scale(r, 100U);
 859         else {
 860                 uint64_t k;
 861
 862                 /* If the passed argument was not a percentage, or out of range, parse as byte size */
 863
 864                 r = parse_size(rvalue, 1024, &k);
 865                 if (r < 0 || k <= 0 || (uint64_t) (size_t) k != k) {
 866                         log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse size value, ignoring: %s", rvalue);
 867                         return 0;
 868                 }
 869
 870                 *sz = PAGE_ALIGN((size_t) k);
 871         }
 872
 873         return 0;
 874 }
 875
 876 int config_parse_user_tasks_max(
 877                 const char* unit,
 878                 const char *filename,
 879                 unsigned line,
 880                 const char *section,
 881                 unsigned section_line,
 882                 const char *lvalue,
 883                 int ltype,
 884                 const char *rvalue,
 885                 void *data,
 886                 void *userdata) {
 887
 888         uint64_t *m = data;
 889         uint64_t k;
 890         int r;
 891
 892         assert(filename);
 893         assert(lvalue);
 894         assert(rvalue);
 895         assert(data);
 896
 897         if (isempty(rvalue)) {
 898                 *m = system_tasks_max_scale(DEFAULT_USER_TASKS_MAX_PERCENTAGE, 100U);
 899                 return 0;
 900         }
 901
 902         if (streq(rvalue, "infinity")) {
 903                 *m = CGROUP_LIMIT_MAX;
 904                 return 0;
 905         }
 906
 907         /* Try to parse as percentage */
 908         r = parse_percent(rvalue);
 909         if (r >= 0)
 910                 k = system_tasks_max_scale(r, 100U);
 911         else {
 912
 913                 /* If the passed argument was not a percentage, or out of range, parse as byte size */
 914
 915                 r = safe_atou64(rvalue, &k);
 916                 if (r < 0) {
 917                         log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse tasks maximum, ignoring: %s", rvalue);
 918                         return 0;
 919                 }
 920         }
 921
 922         if (k <= 0 || k >= UINT64_MAX) {
 923                 log_syntax(unit, LOG_ERR, filename, line, 0, "Tasks maximum out of range, ignoring: %s", rvalue);
 924                 return 0;
 925         }
 926
 927         *m = k;
 928         return 0;
 929 }