src/cgroup-util.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   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 <errno.h>
  23 #include <unistd.h>
  24 #include <signal.h>
  25 #include <string.h>
  26 #include <stdlib.h>
  27 #include <dirent.h>
  28 #include <sys/stat.h>
  29 #include <sys/types.h>
  30 #include <ftw.h>
  31
  32 #include "cgroup-util.h"
  33 #include "log.h"
  34 #include "set.h"
  35 #include "macro.h"
  36 #include "util.h"
  37
  38 int cg_enumerate_processes(const char *controller, const char *path, FILE **_f) {
  39         char *fs;
  40         int r;
  41         FILE *f;
  42
  43         assert(controller);
  44         assert(path);
  45         assert(_f);
  46
  47         if ((r = cg_get_path(controller, path, "cgroup.procs", &fs)) < 0)
  48                 return r;
  49
  50         f = fopen(fs, "re");
  51         free(fs);
  52
  53         if (!f)
  54                 return -errno;
  55
  56         *_f = f;
  57         return 0;
  58 }
  59
  60 int cg_enumerate_tasks(const char *controller, const char *path, FILE **_f) {
  61         char *fs;
  62         int r;
  63         FILE *f;
  64
  65         assert(controller);
  66         assert(path);
  67         assert(_f);
  68
  69         if ((r = cg_get_path(controller, path, "tasks", &fs)) < 0)
  70                 return r;
  71
  72         f = fopen(fs, "re");
  73         free(fs);
  74
  75         if (!f)
  76                 return -errno;
  77
  78         *_f = f;
  79         return 0;
  80 }
  81
  82 int cg_read_pid(FILE *f, pid_t *_pid) {
  83         unsigned long ul;
  84
  85         /* Note that the cgroup.procs might contain duplicates! See
  86          * cgroups.txt for details. */
  87
  88         errno = 0;
  89         if (fscanf(f, "%lu", &ul) != 1) {
  90
  91                 if (feof(f))
  92                         return 0;
  93
  94                 return errno ? -errno : -EIO;
  95         }
  96
  97         if (ul <= 0)
  98                 return -EIO;
  99
 100         *_pid = (pid_t) ul;
 101         return 1;
 102 }
 103
 104 int cg_enumerate_subgroups(const char *controller, const char *path, DIR **_d) {
 105         char *fs;
 106         int r;
 107         DIR *d;
 108
 109         assert(controller);
 110         assert(path);
 111         assert(_d);
 112
 113         /* This is not recursive! */
 114
 115         if ((r = cg_get_path(controller, path, NULL, &fs)) < 0)
 116                 return r;
 117
 118         d = opendir(fs);
 119         free(fs);
 120
 121         if (!d)
 122                 return -errno;
 123
 124         *_d = d;
 125         return 0;
 126 }
 127
 128 int cg_read_subgroup(DIR *d, char **fn) {
 129         struct dirent *de;
 130
 131         assert(d);
 132
 133         errno = 0;
 134         while ((de = readdir(d))) {
 135                 char *b;
 136
 137                 if (de->d_type != DT_DIR)
 138                         continue;
 139
 140                 if (streq(de->d_name, ".") ||
 141                     streq(de->d_name, ".."))
 142                         continue;
 143
 144                 if (!(b = strdup(de->d_name)))
 145                         return -ENOMEM;
 146
 147                 *fn = b;
 148                 return 1;
 149         }
 150
 151         if (errno)
 152                 return -errno;
 153
 154         return 0;
 155 }
 156
 157 int cg_rmdir(const char *controller, const char *path, bool honour_sticky) {
 158         char *p;
 159         int r;
 160
 161         r = cg_get_path(controller, path, NULL, &p);
 162         if (r < 0)
 163                 return r;
 164
 165         if (honour_sticky) {
 166                 char *tasks;
 167
 168                 /* If the sticky bit is set don't remove the directory */
 169
 170                 tasks = strappend(p, "/tasks");
 171                 if (!tasks) {
 172                         free(p);
 173                         return -ENOMEM;
 174                 }
 175
 176                 r = file_is_priv_sticky(tasks);
 177                 free(tasks);
 178
 179                 if (r > 0) {
 180                         free(p);
 181                         return 0;
 182                 }
 183         }
 184
 185         r = rmdir(p);
 186         free(p);
 187
 188         return (r < 0 && errno != ENOENT) ? -errno : 0;
 189 }
 190
 191 int cg_kill(const char *controller, const char *path, int sig, bool sigcont, bool ignore_self, Set *s) {
 192         bool done = false;
 193         int r, ret = 0;
 194         pid_t my_pid;
 195         FILE *f = NULL;
 196         Set *allocated_set = NULL;
 197
 198         assert(controller);
 199         assert(path);
 200         assert(sig >= 0);
 201
 202         /* This goes through the tasks list and kills them all. This
 203          * is repeated until no further processes are added to the
 204          * tasks list, to properly handle forking processes */
 205
 206         if (!s)
 207                 if (!(s = allocated_set = set_new(trivial_hash_func, trivial_compare_func)))
 208                         return -ENOMEM;
 209
 210         my_pid = getpid();
 211
 212         do {
 213                 pid_t pid = 0;
 214                 done = true;
 215
 216                 if ((r = cg_enumerate_processes(controller, path, &f)) < 0) {
 217                         if (ret >= 0 && r != -ENOENT)
 218                                 ret = r;
 219
 220                         goto finish;
 221                 }
 222
 223                 while ((r = cg_read_pid(f, &pid)) > 0) {
 224
 225                         if (pid == my_pid && ignore_self)
 226                                 continue;
 227
 228                         if (set_get(s, LONG_TO_PTR(pid)) == LONG_TO_PTR(pid))
 229                                 continue;
 230
 231                         /* If we haven't killed this process yet, kill
 232                          * it */
 233                         if (kill(pid, sig) < 0) {
 234                                 if (ret >= 0 && errno != ESRCH)
 235                                         ret = -errno;
 236                         } else if (ret == 0) {
 237
 238                                 if (sigcont)
 239                                         kill(pid, SIGCONT);
 240
 241                                 ret = 1;
 242                         }
 243
 244                         done = false;
 245
 246                         if ((r = set_put(s, LONG_TO_PTR(pid))) < 0) {
 247                                 if (ret >= 0)
 248                                         ret = r;
 249
 250                                 goto finish;
 251                         }
 252                 }
 253
 254                 if (r < 0) {
 255                         if (ret >= 0)
 256                                 ret = r;
 257
 258                         goto finish;
 259                 }
 260
 261                 fclose(f);
 262                 f = NULL;
 263
 264                 /* To avoid racing against processes which fork
 265                  * quicker than we can kill them we repeat this until
 266                  * no new pids need to be killed. */
 267
 268         } while (!done);
 269
 270 finish:
 271         if (allocated_set)
 272                 set_free(allocated_set);
 273
 274         if (f)
 275                 fclose(f);
 276
 277         return ret;
 278 }
 279
 280 int cg_kill_recursive(const char *controller, const char *path, int sig, bool sigcont, bool ignore_self, bool rem, Set *s) {
 281         int r, ret = 0;
 282         DIR *d = NULL;
 283         char *fn;
 284         Set *allocated_set = NULL;
 285
 286         assert(path);
 287         assert(controller);
 288         assert(sig >= 0);
 289
 290         if (!s)
 291                 if (!(s = allocated_set = set_new(trivial_hash_func, trivial_compare_func)))
 292                         return -ENOMEM;
 293
 294         ret = cg_kill(controller, path, sig, sigcont, ignore_self, s);
 295
 296         if ((r = cg_enumerate_subgroups(controller, path, &d)) < 0) {
 297                 if (ret >= 0 && r != -ENOENT)
 298                         ret = r;
 299
 300                 goto finish;
 301         }
 302
 303         while ((r = cg_read_subgroup(d, &fn)) > 0) {
 304                 char *p = NULL;
 305
 306                 r = asprintf(&p, "%s/%s", path, fn);
 307                 free(fn);
 308
 309                 if (r < 0) {
 310                         if (ret >= 0)
 311                                 ret = -ENOMEM;
 312
 313                         goto finish;
 314                 }
 315
 316                 r = cg_kill_recursive(controller, p, sig, sigcont, ignore_self, rem, s);
 317                 free(p);
 318
 319                 if (r != 0 && ret >= 0)
 320                         ret = r;
 321         }
 322
 323         if (r < 0 && ret >= 0)
 324                 ret = r;
 325
 326         if (rem)
 327                 if ((r = cg_rmdir(controller, path, true)) < 0) {
 328                         if (ret >= 0 &&
 329                             r != -ENOENT &&
 330                             r != -EBUSY)
 331                                 ret = r;
 332                 }
 333
 334 finish:
 335         if (d)
 336                 closedir(d);
 337
 338         if (allocated_set)
 339                 set_free(allocated_set);
 340
 341         return ret;
 342 }
 343
 344 int cg_kill_recursive_and_wait(const char *controller, const char *path, bool rem) {
 345         unsigned i;
 346
 347         assert(path);
 348         assert(controller);
 349
 350         /* This safely kills all processes; first it sends a SIGTERM,
 351          * then checks 8 times after 200ms whether the group is now
 352          * empty, then kills everything that is left with SIGKILL and
 353          * finally checks 5 times after 200ms each whether the group
 354          * is finally empty. */
 355
 356         for (i = 0; i < 15; i++) {
 357                 int sig, r;
 358
 359                 if (i <= 0)
 360                         sig = SIGTERM;
 361                 else if (i == 9)
 362                         sig = SIGKILL;
 363                 else
 364                         sig = 0;
 365
 366                 if ((r = cg_kill_recursive(controller, path, sig, true, true, rem, NULL)) <= 0)
 367                         return r;
 368
 369                 usleep(200 * USEC_PER_MSEC);
 370         }
 371
 372         return 0;
 373 }
 374
 375 int cg_migrate(const char *controller, const char *from, const char *to, bool ignore_self) {
 376         bool done = false;
 377         Set *s;
 378         int r, ret = 0;
 379         pid_t my_pid;
 380         FILE *f = NULL;
 381
 382         assert(controller);
 383         assert(from);
 384         assert(to);
 385
 386         if (!(s = set_new(trivial_hash_func, trivial_compare_func)))
 387                 return -ENOMEM;
 388
 389         my_pid = getpid();
 390
 391         do {
 392                 pid_t pid = 0;
 393                 done = true;
 394
 395                 if ((r = cg_enumerate_tasks(controller, from, &f)) < 0) {
 396                         if (ret >= 0 && r != -ENOENT)
 397                                 ret = r;
 398
 399                         goto finish;
 400                 }
 401
 402                 while ((r = cg_read_pid(f, &pid)) > 0) {
 403
 404                         /* This might do weird stuff if we aren't a
 405                          * single-threaded program. However, we
 406                          * luckily know we are not */
 407                         if (pid == my_pid && ignore_self)
 408                                 continue;
 409
 410                         if (set_get(s, LONG_TO_PTR(pid)) == LONG_TO_PTR(pid))
 411                                 continue;
 412
 413                         if ((r = cg_attach(controller, to, pid)) < 0) {
 414                                 if (ret >= 0 && r != -ESRCH)
 415                                         ret = r;
 416                         } else if (ret == 0)
 417                                 ret = 1;
 418
 419                         done = false;
 420
 421                         if ((r = set_put(s, LONG_TO_PTR(pid))) < 0) {
 422                                 if (ret >= 0)
 423                                         ret = r;
 424
 425                                 goto finish;
 426                         }
 427                 }
 428
 429                 if (r < 0) {
 430                         if (ret >= 0)
 431                                 ret = r;
 432
 433                         goto finish;
 434                 }
 435
 436                 fclose(f);
 437                 f = NULL;
 438
 439         } while (!done);
 440
 441 finish:
 442         set_free(s);
 443
 444         if (f)
 445                 fclose(f);
 446
 447         return ret;
 448 }
 449
 450 int cg_migrate_recursive(const char *controller, const char *from, const char *to, bool ignore_self, bool rem) {
 451         int r, ret = 0;
 452         DIR *d = NULL;
 453         char *fn;
 454
 455         assert(controller);
 456         assert(from);
 457         assert(to);
 458
 459         ret = cg_migrate(controller, from, to, ignore_self);
 460
 461         if ((r = cg_enumerate_subgroups(controller, from, &d)) < 0) {
 462                 if (ret >= 0 && r != -ENOENT)
 463                         ret = r;
 464                 goto finish;
 465         }
 466
 467         while ((r = cg_read_subgroup(d, &fn)) > 0) {
 468                 char *p = NULL;
 469
 470                 r = asprintf(&p, "%s/%s", from, fn);
 471                 free(fn);
 472
 473                 if (r < 0) {
 474                         if (ret >= 0)
 475                                 ret = -ENOMEM;
 476
 477                         goto finish;
 478                 }
 479
 480                 r = cg_migrate_recursive(controller, p, to, ignore_self, rem);
 481                 free(p);
 482
 483                 if (r != 0 && ret >= 0)
 484                         ret = r;
 485         }
 486
 487         if (r < 0 && ret >= 0)
 488                 ret = r;
 489
 490         if (rem)
 491                 if ((r = cg_rmdir(controller, from, true)) < 0) {
 492                         if (ret >= 0 &&
 493                             r != -ENOENT &&
 494                             r != -EBUSY)
 495                                 ret = r;
 496                 }
 497
 498 finish:
 499         if (d)
 500                 closedir(d);
 501
 502         return ret;
 503 }
 504
 505 int cg_get_path(const char *controller, const char *path, const char *suffix, char **fs) {
 506         const char *p;
 507         char *t;
 508         static __thread bool good = false;
 509
 510         assert(controller);
 511         assert(fs);
 512
 513         if (_unlikely_(!good)) {
 514                 int r;
 515
 516                 r = path_is_mount_point("/sys/fs/cgroup", false);
 517                 if (r <= 0)
 518                         return r < 0 ? r : -ENOENT;
 519
 520                 /* Cache this to save a few stat()s */
 521                 good = true;
 522         }
 523
 524         if (isempty(controller))
 525                 return -EINVAL;
 526
 527         /* This is a very minimal lookup from controller names to
 528          * paths. Since we have mounted most hierarchies ourselves
 529          * should be kinda safe, but eventually we might want to
 530          * extend this to have a fallback to actually check
 531          * /proc/mounts. Might need caching then. */
 532
 533         if (streq(controller, SYSTEMD_CGROUP_CONTROLLER))
 534                 p = "systemd";
 535         else if (startswith(controller, "name="))
 536                 p = controller + 5;
 537         else
 538                 p = controller;
 539
 540         if (path && suffix)
 541                 t = join("/sys/fs/cgroup/", p, "/", path, "/", suffix, NULL);
 542         else if (path)
 543                 t = join("/sys/fs/cgroup/", p, "/", path, NULL);
 544         else if (suffix)
 545                 t = join("/sys/fs/cgroup/", p, "/", suffix, NULL);
 546         else
 547                 t = join("/sys/fs/cgroup/", p, NULL);
 548
 549         if (!t)
 550                 return -ENOMEM;
 551
 552         path_kill_slashes(t);
 553
 554         *fs = t;
 555         return 0;
 556 }
 557
 558 static int trim_cb(const char *path, const struct stat *sb, int typeflag, struct FTW *ftwbuf) {
 559         char *p;
 560         bool is_sticky;
 561
 562         if (typeflag != FTW_DP)
 563                 return 0;
 564
 565         if (ftwbuf->level < 1)
 566                 return 0;
 567
 568         p = strappend(path, "/tasks");
 569         if (!p) {
 570                 errno = ENOMEM;
 571                 return 1;
 572         }
 573
 574         is_sticky = file_is_priv_sticky(p) > 0;
 575         free(p);
 576
 577         if (is_sticky)
 578                 return 0;
 579
 580         rmdir(path);
 581         return 0;
 582 }
 583
 584 int cg_trim(const char *controller, const char *path, bool delete_root) {
 585         char *fs;
 586         int r = 0;
 587
 588         assert(controller);
 589         assert(path);
 590
 591         r = cg_get_path(controller, path, NULL, &fs);
 592         if (r < 0)
 593                 return r;
 594
 595         errno = 0;
 596         if (nftw(fs, trim_cb, 64, FTW_DEPTH|FTW_MOUNT|FTW_PHYS) < 0)
 597                 r = errno ? -errno : -EIO;
 598
 599         if (delete_root) {
 600                 bool is_sticky;
 601                 char *p;
 602
 603                 p = strappend(fs, "/tasks");
 604                 if (!p) {
 605                         free(fs);
 606                         return -ENOMEM;
 607                 }
 608
 609                 is_sticky = file_is_priv_sticky(p) > 0;
 610                 free(p);
 611
 612                 if (!is_sticky)
 613                         if (rmdir(fs) < 0 && errno != ENOENT) {
 614                                 if (r == 0)
 615                                         r = -errno;
 616                         }
 617         }
 618
 619         free(fs);
 620
 621         return r;
 622 }
 623
 624 int cg_delete(const char *controller, const char *path) {
 625         char *parent;
 626         int r;
 627
 628         assert(controller);
 629         assert(path);
 630
 631         if ((r = parent_of_path(path, &parent)) < 0)
 632                 return r;
 633
 634         r = cg_migrate_recursive(controller, path, parent, false, true);
 635         free(parent);
 636
 637         return r == -ENOENT ? 0 : r;
 638 }
 639
 640 int cg_create(const char *controller, const char *path) {
 641         char *fs;
 642         int r;
 643
 644         assert(controller);
 645         assert(path);
 646
 647         if ((r = cg_get_path(controller, path, NULL, &fs)) < 0)
 648                 return r;
 649
 650         r = mkdir_parents(fs, 0755);
 651
 652         if (r >= 0) {
 653                 if (mkdir(fs, 0755) >= 0)
 654                         r = 1;
 655                 else if (errno == EEXIST)
 656                         r = 0;
 657                 else
 658                         r = -errno;
 659         }
 660
 661         free(fs);
 662
 663         return r;
 664 }
 665
 666 int cg_attach(const char *controller, const char *path, pid_t pid) {
 667         char *fs;
 668         int r;
 669         char c[32];
 670
 671         assert(controller);
 672         assert(path);
 673         assert(pid >= 0);
 674
 675         if ((r = cg_get_path(controller, path, "tasks", &fs)) < 0)
 676                 return r;
 677
 678         if (pid == 0)
 679                 pid = getpid();
 680
 681         snprintf(c, sizeof(c), "%lu\n", (unsigned long) pid);
 682         char_array_0(c);
 683
 684         r = write_one_line_file(fs, c);
 685         free(fs);
 686
 687         return r;
 688 }
 689
 690 int cg_create_and_attach(const char *controller, const char *path, pid_t pid) {
 691         int r, q;
 692
 693         assert(controller);
 694         assert(path);
 695         assert(pid >= 0);
 696
 697         if ((r = cg_create(controller, path)) < 0)
 698                 return r;
 699
 700         if ((q = cg_attach(controller, path, pid)) < 0)
 701                 return q;
 702
 703         /* This does not remove the cgroup on failure */
 704
 705         return r;
 706 }
 707
 708 int cg_set_group_access(const char *controller, const char *path, mode_t mode, uid_t uid, gid_t gid) {
 709         char *fs;
 710         int r;
 711
 712         assert(controller);
 713         assert(path);
 714
 715         if (mode != (mode_t) -1)
 716                 mode &= 0777;
 717
 718         r = cg_get_path(controller, path, NULL, &fs);
 719         if (r < 0)
 720                 return r;
 721
 722         r = chmod_and_chown(fs, mode, uid, gid);
 723         free(fs);
 724
 725         return r;
 726 }
 727
 728 int cg_set_task_access(const char *controller, const char *path, mode_t mode, uid_t uid, gid_t gid, int sticky) {
 729         char *fs;
 730         int r;
 731
 732         assert(controller);
 733         assert(path);
 734
 735         if (mode == (mode_t) -1 && uid == (uid_t) -1 && gid == (gid_t) -1 && sticky < 0)
 736                 return 0;
 737
 738         if (mode != (mode_t) -1)
 739                 mode &= 0666;
 740
 741         r = cg_get_path(controller, path, "tasks", &fs);
 742         if (r < 0)
 743                 return r;
 744
 745         if (sticky >= 0 && mode != (mode_t) -1)
 746                 /* Both mode and sticky param are passed */
 747                 mode |= (sticky ? S_ISVTX : 0);
 748         else if ((sticky >= 0 && mode == (mode_t) -1) ||
 749                  (mode != (mode_t) -1 && sticky < 0)) {
 750                 struct stat st;
 751
 752                 /* Only one param is passed, hence read the current
 753                  * mode from the file itself */
 754
 755                 r = lstat(fs, &st);
 756                 if (r < 0) {
 757                         free(fs);
 758                         return -errno;
 759                 }
 760
 761                 if (mode == (mode_t) -1)
 762                         /* No mode set, we just shall set the sticky bit */
 763                         mode = (st.st_mode & ~S_ISVTX) | (sticky ? S_ISVTX : 0);
 764                 else
 765                         /* Only mode set, leave sticky bit untouched */
 766                         mode = (st.st_mode & ~0777) | mode;
 767         }
 768
 769         r = chmod_and_chown(fs, mode, uid, gid);
 770         free(fs);
 771
 772         return r;
 773 }
 774
 775 int cg_get_by_pid(const char *controller, pid_t pid, char **path) {
 776         int r;
 777         char *p = NULL;
 778         FILE *f;
 779         char *fs;
 780         size_t cs;
 781
 782         assert(controller);
 783         assert(path);
 784         assert(pid >= 0);
 785
 786         if (pid == 0)
 787                 pid = getpid();
 788
 789         if (asprintf(&fs, "/proc/%lu/cgroup", (unsigned long) pid) < 0)
 790                 return -ENOMEM;
 791
 792         f = fopen(fs, "re");
 793         free(fs);
 794
 795         if (!f)
 796                 return errno == ENOENT ? -ESRCH : -errno;
 797
 798         cs = strlen(controller);
 799
 800         while (!feof(f)) {
 801                 char line[LINE_MAX];
 802                 char *l;
 803
 804                 errno = 0;
 805                 if (!(fgets(line, sizeof(line), f))) {
 806                         if (feof(f))
 807                                 break;
 808
 809                         r = errno ? -errno : -EIO;
 810                         goto finish;
 811                 }
 812
 813                 truncate_nl(line);
 814
 815                 if (!(l = strchr(line, ':')))
 816                         continue;
 817
 818                 l++;
 819                 if (strncmp(l, controller, cs) != 0)
 820                         continue;
 821
 822                 if (l[cs] != ':')
 823                         continue;
 824
 825                 if (!(p = strdup(l + cs + 1))) {
 826                         r = -ENOMEM;
 827                         goto finish;
 828                 }
 829
 830                 *path = p;
 831                 r = 0;
 832                 goto finish;
 833         }
 834
 835         r = -ENOENT;
 836
 837 finish:
 838         fclose(f);
 839
 840         return r;
 841 }
 842
 843 int cg_install_release_agent(const char *controller, const char *agent) {
 844         char *fs = NULL, *contents = NULL, *line = NULL, *sc;
 845         int r;
 846
 847         assert(controller);
 848         assert(agent);
 849
 850         if ((r = cg_get_path(controller, NULL, "release_agent", &fs)) < 0)
 851                 return r;
 852
 853         if ((r = read_one_line_file(fs, &contents)) < 0)
 854                 goto finish;
 855
 856         sc = strstrip(contents);
 857         if (sc[0] == 0) {
 858
 859                 if (asprintf(&line, "%s\n", agent) < 0) {
 860                         r = -ENOMEM;
 861                         goto finish;
 862                 }
 863
 864                 if ((r = write_one_line_file(fs, line)) < 0)
 865                         goto finish;
 866
 867         } else if (!streq(sc, agent)) {
 868                 r = -EEXIST;
 869                 goto finish;
 870         }
 871
 872         free(fs);
 873         fs = NULL;
 874         if ((r = cg_get_path(controller, NULL, "notify_on_release", &fs)) < 0)
 875                 goto finish;
 876
 877         free(contents);
 878         contents = NULL;
 879         if ((r = read_one_line_file(fs, &contents)) < 0)
 880                 goto finish;
 881
 882         sc = strstrip(contents);
 883
 884         if (streq(sc, "0")) {
 885                 if ((r = write_one_line_file(fs, "1\n")) < 0)
 886                         goto finish;
 887
 888                 r = 1;
 889         } else if (!streq(sc, "1")) {
 890                 r = -EIO;
 891                 goto finish;
 892         } else
 893                 r = 0;
 894
 895 finish:
 896         free(fs);
 897         free(contents);
 898         free(line);
 899
 900         return r;
 901 }
 902
 903 int cg_is_empty(const char *controller, const char *path, bool ignore_self) {
 904         pid_t pid = 0;
 905         int r;
 906         FILE *f = NULL;
 907         bool found = false;
 908
 909         assert(controller);
 910         assert(path);
 911
 912         if ((r = cg_enumerate_tasks(controller, path, &f)) < 0)
 913                 return r == -ENOENT ? 1 : r;
 914
 915         while ((r = cg_read_pid(f, &pid)) > 0) {
 916
 917                 if (ignore_self && pid == getpid())
 918                         continue;
 919
 920                 found = true;
 921                 break;
 922         }
 923
 924         fclose(f);
 925
 926         if (r < 0)
 927                 return r;
 928
 929         return !found;
 930 }
 931
 932 int cg_is_empty_recursive(const char *controller, const char *path, bool ignore_self) {
 933         int r;
 934         DIR *d = NULL;
 935         char *fn;
 936
 937         assert(controller);
 938         assert(path);
 939
 940         if ((r = cg_is_empty(controller, path, ignore_self)) <= 0)
 941                 return r;
 942
 943         if ((r = cg_enumerate_subgroups(controller, path, &d)) < 0)
 944                 return r == -ENOENT ? 1 : r;
 945
 946         while ((r = cg_read_subgroup(d, &fn)) > 0) {
 947                 char *p = NULL;
 948
 949                 r = asprintf(&p, "%s/%s", path, fn);
 950                 free(fn);
 951
 952                 if (r < 0) {
 953                         r = -ENOMEM;
 954                         goto finish;
 955                 }
 956
 957                 r = cg_is_empty_recursive(controller, p, ignore_self);
 958                 free(p);
 959
 960                 if (r <= 0)
 961                         goto finish;
 962         }
 963
 964         if (r >= 0)
 965                 r = 1;
 966
 967 finish:
 968
 969         if (d)
 970                 closedir(d);
 971
 972         return r;
 973 }
 974
 975 int cg_split_spec(const char *spec, char **controller, char **path) {
 976         const char *e;
 977         char *t = NULL, *u = NULL;
 978
 979         assert(spec);
 980         assert(controller || path);
 981
 982         if (*spec == '/') {
 983
 984                 if (path) {
 985                         if (!(t = strdup(spec)))
 986                                 return -ENOMEM;
 987
 988                         *path = t;
 989                 }
 990
 991                 if (controller)
 992                         *controller = NULL;
 993
 994                 return 0;
 995         }
 996
 997         if (!(e = strchr(spec, ':'))) {
 998
 999                 if (strchr(spec, '/') || spec[0] == 0)
1000                         return -EINVAL;
1001
1002                 if (controller) {
1003                         if (!(t = strdup(spec)))
1004                                 return -ENOMEM;
1005
1006                         *controller = t;
1007                 }
1008
1009                 if (path)
1010                         *path = NULL;
1011
1012                 return 0;
1013         }
1014
1015         if (e[1] != '/' ||
1016             e == spec ||
1017             memchr(spec, '/', e-spec))
1018                 return -EINVAL;
1019
1020         if (controller)
1021                 if (!(t = strndup(spec, e-spec)))
1022                         return -ENOMEM;
1023
1024         if (path)
1025                 if (!(u = strdup(e+1))) {
1026                         free(t);
1027                         return -ENOMEM;
1028                 }
1029
1030         if (controller)
1031                 *controller = t;
1032
1033         if (path)
1034                 *path = u;
1035
1036         return 0;
1037 }
1038
1039 int cg_join_spec(const char *controller, const char *path, char **spec) {
1040         assert(controller);
1041         assert(path);
1042
1043         if (!path_is_absolute(path) ||
1044             controller[0] == 0 ||
1045             strchr(controller, ':') ||
1046             strchr(controller, '/'))
1047                 return -EINVAL;
1048
1049         if (asprintf(spec, "%s:%s", controller, path) < 0)
1050                 return -ENOMEM;
1051
1052         return 0;
1053 }
1054
1055 int cg_fix_path(const char *path, char **result) {
1056         char *t, *c, *p;
1057         int r;
1058
1059         assert(path);
1060         assert(result);
1061
1062         /* First check if it already is a filesystem path */
1063         if (path_is_absolute(path) &&
1064             path_startswith(path, "/sys/fs/cgroup") &&
1065             access(path, F_OK) >= 0) {
1066
1067                 if (!(t = strdup(path)))
1068                         return -ENOMEM;
1069
1070                 *result = t;
1071                 return 0;
1072         }
1073
1074         /* Otherwise treat it as cg spec */
1075         if ((r = cg_split_spec(path, &c, &p)) < 0)
1076                 return r;
1077
1078         r = cg_get_path(c ? c : SYSTEMD_CGROUP_CONTROLLER, p ? p : "/", NULL, result);
1079         free(c);
1080         free(p);
1081
1082         return r;
1083 }
1084
1085 int cg_get_user_path(char **path) {
1086         char *root, *p;
1087
1088         assert(path);
1089
1090         /* Figure out the place to put user cgroups below. We use the
1091          * same as PID 1 has but with the "/system" suffix replaced by
1092          * "/user" */
1093
1094         if (cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 1, &root) < 0)
1095                 p = strdup("/user");
1096         else {
1097                 if (endswith(root, "/system"))
1098                         root[strlen(root) - 7] = 0;
1099                 else if (streq(root, "/"))
1100                         root[0] = 0;
1101
1102                 p = strappend(root, "/user");
1103                 free(root);
1104         }
1105
1106         if (!p)
1107                 return -ENOMEM;
1108
1109         *path = p;
1110         return 0;
1111 }