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