src/basic/util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 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 <alloca.h>
  21 #include <dirent.h>
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <sched.h>
  25 #include <signal.h>
  26 #include <stdarg.h>
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <sys/mman.h>
  31 #include <sys/prctl.h>
  32 #include <sys/statfs.h>
  33 #include <sys/sysmacros.h>
  34 #include <sys/types.h>
  35 #include <unistd.h>
  36
  37 #include "alloc-util.h"
  38 #include "build.h"
  39 #include "cgroup-util.h"
  40 #include "def.h"
  41 #include "dirent-util.h"
  42 #include "fd-util.h"
  43 #include "fileio.h"
  44 #include "format-util.h"
  45 #include "hashmap.h"
  46 #include "hostname-util.h"
  47 #include "log.h"
  48 #include "macro.h"
  49 #include "missing.h"
  50 #include "parse-util.h"
  51 #include "path-util.h"
  52 #include "process-util.h"
  53 #include "set.h"
  54 #include "signal-util.h"
  55 #include "stat-util.h"
  56 #include "string-util.h"
  57 #include "strv.h"
  58 #include "time-util.h"
  59 #include "umask-util.h"
  60 #include "user-util.h"
  61 #include "util.h"
  62
  63 /* Put this test here for a lack of better place */
  64 assert_cc(EAGAIN == EWOULDBLOCK);
  65
  66 int saved_argc = 0;
  67 char **saved_argv = NULL;
  68 static int saved_in_initrd = -1;
  69
  70 size_t page_size(void) {
  71         static thread_local size_t pgsz = 0;
  72         long r;
  73
  74         if (_likely_(pgsz > 0))
  75                 return pgsz;
  76
  77         r = sysconf(_SC_PAGESIZE);
  78         assert(r > 0);
  79
  80         pgsz = (size_t) r;
  81         return pgsz;
  82 }
  83
  84 static int do_execute(char **directories, usec_t timeout, char *argv[]) {
  85         _cleanup_hashmap_free_free_ Hashmap *pids = NULL;
  86         _cleanup_set_free_free_ Set *seen = NULL;
  87         char **directory;
  88
  89         /* We fork this all off from a child process so that we can
  90          * somewhat cleanly make use of SIGALRM to set a time limit */
  91
  92         (void) reset_all_signal_handlers();
  93         (void) reset_signal_mask();
  94
  95         assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
  96
  97         pids = hashmap_new(NULL);
  98         if (!pids)
  99                 return log_oom();
 100
 101         seen = set_new(&string_hash_ops);
 102         if (!seen)
 103                 return log_oom();
 104
 105         STRV_FOREACH(directory, directories) {
 106                 _cleanup_closedir_ DIR *d;
 107                 struct dirent *de;
 108
 109                 d = opendir(*directory);
 110                 if (!d) {
 111                         if (errno == ENOENT)
 112                                 continue;
 113
 114                         return log_error_errno(errno, "Failed to open directory %s: %m", *directory);
 115                 }
 116
 117                 FOREACH_DIRENT(de, d, break) {
 118                         _cleanup_free_ char *path = NULL;
 119                         pid_t pid;
 120                         int r;
 121
 122                         if (!dirent_is_file(de))
 123                                 continue;
 124
 125                         if (set_contains(seen, de->d_name)) {
 126                                 log_debug("%1$s/%2$s skipped (%2$s was already seen).", *directory, de->d_name);
 127                                 continue;
 128                         }
 129
 130                         r = set_put_strdup(seen, de->d_name);
 131                         if (r < 0)
 132                                 return log_oom();
 133
 134                         path = strjoin(*directory, "/", de->d_name);
 135                         if (!path)
 136                                 return log_oom();
 137
 138                         if (null_or_empty_path(path)) {
 139                                 log_debug("%s is empty (a mask).", path);
 140                                 continue;
 141                         }
 142
 143                         pid = fork();
 144                         if (pid < 0) {
 145                                 log_error_errno(errno, "Failed to fork: %m");
 146                                 continue;
 147                         } else if (pid == 0) {
 148                                 char *_argv[2];
 149
 150                                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
 151
 152                                 if (!argv) {
 153                                         _argv[0] = path;
 154                                         _argv[1] = NULL;
 155                                         argv = _argv;
 156                                 } else
 157                                         argv[0] = path;
 158
 159                                 execv(path, argv);
 160                                 return log_error_errno(errno, "Failed to execute %s: %m", path);
 161                         }
 162
 163                         log_debug("Spawned %s as " PID_FMT ".", path, pid);
 164
 165                         r = hashmap_put(pids, PID_TO_PTR(pid), path);
 166                         if (r < 0)
 167                                 return log_oom();
 168                         path = NULL;
 169                 }
 170         }
 171
 172         /* Abort execution of this process after the timout. We simply
 173          * rely on SIGALRM as default action terminating the process,
 174          * and turn on alarm(). */
 175
 176         if (timeout != USEC_INFINITY)
 177                 alarm((timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
 178
 179         while (!hashmap_isempty(pids)) {
 180                 _cleanup_free_ char *path = NULL;
 181                 pid_t pid;
 182
 183                 pid = PTR_TO_PID(hashmap_first_key(pids));
 184                 assert(pid > 0);
 185
 186                 path = hashmap_remove(pids, PID_TO_PTR(pid));
 187                 assert(path);
 188
 189                 wait_for_terminate_and_warn(path, pid, true);
 190         }
 191
 192         return 0;
 193 }
 194
 195 void execute_directories(const char* const* directories, usec_t timeout, char *argv[]) {
 196         pid_t executor_pid;
 197         int r;
 198         char *name;
 199         char **dirs = (char**) directories;
 200
 201         assert(!strv_isempty(dirs));
 202
 203         name = basename(dirs[0]);
 204         assert(!isempty(name));
 205
 206         /* Executes all binaries in the directories in parallel and waits
 207          * for them to finish. Optionally a timeout is applied. If a file
 208          * with the same name exists in more than one directory, the
 209          * earliest one wins. */
 210
 211         executor_pid = fork();
 212         if (executor_pid < 0) {
 213                 log_error_errno(errno, "Failed to fork: %m");
 214                 return;
 215
 216         } else if (executor_pid == 0) {
 217                 r = do_execute(dirs, timeout, argv);
 218                 _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
 219         }
 220
 221         wait_for_terminate_and_warn(name, executor_pid, true);
 222 }
 223
 224 bool plymouth_running(void) {
 225         return access("/run/plymouth/pid", F_OK) >= 0;
 226 }
 227
 228 bool display_is_local(const char *display) {
 229         assert(display);
 230
 231         return
 232                 display[0] == ':' &&
 233                 display[1] >= '0' &&
 234                 display[1] <= '9';
 235 }
 236
 237 int socket_from_display(const char *display, char **path) {
 238         size_t k;
 239         char *f, *c;
 240
 241         assert(display);
 242         assert(path);
 243
 244         if (!display_is_local(display))
 245                 return -EINVAL;
 246
 247         k = strspn(display+1, "0123456789");
 248
 249         f = new(char, strlen("/tmp/.X11-unix/X") + k + 1);
 250         if (!f)
 251                 return -ENOMEM;
 252
 253         c = stpcpy(f, "/tmp/.X11-unix/X");
 254         memcpy(c, display+1, k);
 255         c[k] = 0;
 256
 257         *path = f;
 258
 259         return 0;
 260 }
 261
 262 int block_get_whole_disk(dev_t d, dev_t *ret) {
 263         char *p, *s;
 264         int r;
 265         unsigned n, m;
 266
 267         assert(ret);
 268
 269         /* If it has a queue this is good enough for us */
 270         if (asprintf(&p, "/sys/dev/block/%u:%u/queue", major(d), minor(d)) < 0)
 271                 return -ENOMEM;
 272
 273         r = access(p, F_OK);
 274         free(p);
 275
 276         if (r >= 0) {
 277                 *ret = d;
 278                 return 0;
 279         }
 280
 281         /* If it is a partition find the originating device */
 282         if (asprintf(&p, "/sys/dev/block/%u:%u/partition", major(d), minor(d)) < 0)
 283                 return -ENOMEM;
 284
 285         r = access(p, F_OK);
 286         free(p);
 287
 288         if (r < 0)
 289                 return -ENOENT;
 290
 291         /* Get parent dev_t */
 292         if (asprintf(&p, "/sys/dev/block/%u:%u/../dev", major(d), minor(d)) < 0)
 293                 return -ENOMEM;
 294
 295         r = read_one_line_file(p, &s);
 296         free(p);
 297
 298         if (r < 0)
 299                 return r;
 300
 301         r = sscanf(s, "%u:%u", &m, &n);
 302         free(s);
 303
 304         if (r != 2)
 305                 return -EINVAL;
 306
 307         /* Only return this if it is really good enough for us. */
 308         if (asprintf(&p, "/sys/dev/block/%u:%u/queue", m, n) < 0)
 309                 return -ENOMEM;
 310
 311         r = access(p, F_OK);
 312         free(p);
 313
 314         if (r >= 0) {
 315                 *ret = makedev(m, n);
 316                 return 0;
 317         }
 318
 319         return -ENOENT;
 320 }
 321
 322 bool kexec_loaded(void) {
 323        bool loaded = false;
 324        char *s;
 325
 326        if (read_one_line_file("/sys/kernel/kexec_loaded", &s) >= 0) {
 327                if (s[0] == '1')
 328                        loaded = true;
 329                free(s);
 330        }
 331        return loaded;
 332 }
 333
 334 int prot_from_flags(int flags) {
 335
 336         switch (flags & O_ACCMODE) {
 337
 338         case O_RDONLY:
 339                 return PROT_READ;
 340
 341         case O_WRONLY:
 342                 return PROT_WRITE;
 343
 344         case O_RDWR:
 345                 return PROT_READ|PROT_WRITE;
 346
 347         default:
 348                 return -EINVAL;
 349         }
 350 }
 351
 352 int fork_agent(pid_t *pid, const int except[], unsigned n_except, const char *path, ...) {
 353         bool stdout_is_tty, stderr_is_tty;
 354         pid_t parent_pid, agent_pid;
 355         sigset_t ss, saved_ss;
 356         unsigned n, i;
 357         va_list ap;
 358         char **l;
 359
 360         assert(pid);
 361         assert(path);
 362
 363         /* Spawns a temporary TTY agent, making sure it goes away when
 364          * we go away */
 365
 366         parent_pid = getpid();
 367
 368         /* First we temporarily block all signals, so that the new
 369          * child has them blocked initially. This way, we can be sure
 370          * that SIGTERMs are not lost we might send to the agent. */
 371         assert_se(sigfillset(&ss) >= 0);
 372         assert_se(sigprocmask(SIG_SETMASK, &ss, &saved_ss) >= 0);
 373
 374         agent_pid = fork();
 375         if (agent_pid < 0) {
 376                 assert_se(sigprocmask(SIG_SETMASK, &saved_ss, NULL) >= 0);
 377                 return -errno;
 378         }
 379
 380         if (agent_pid != 0) {
 381                 assert_se(sigprocmask(SIG_SETMASK, &saved_ss, NULL) >= 0);
 382                 *pid = agent_pid;
 383                 return 0;
 384         }
 385
 386         /* In the child:
 387          *
 388          * Make sure the agent goes away when the parent dies */
 389         if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
 390                 _exit(EXIT_FAILURE);
 391
 392         /* Make sure we actually can kill the agent, if we need to, in
 393          * case somebody invoked us from a shell script that trapped
 394          * SIGTERM or so... */
 395         (void) reset_all_signal_handlers();
 396         (void) reset_signal_mask();
 397
 398         /* Check whether our parent died before we were able
 399          * to set the death signal and unblock the signals */
 400         if (getppid() != parent_pid)
 401                 _exit(EXIT_SUCCESS);
 402
 403         /* Don't leak fds to the agent */
 404         close_all_fds(except, n_except);
 405
 406         stdout_is_tty = isatty(STDOUT_FILENO);
 407         stderr_is_tty = isatty(STDERR_FILENO);
 408
 409         if (!stdout_is_tty || !stderr_is_tty) {
 410                 int fd;
 411
 412                 /* Detach from stdout/stderr. and reopen
 413                  * /dev/tty for them. This is important to
 414                  * ensure that when systemctl is started via
 415                  * popen() or a similar call that expects to
 416                  * read EOF we actually do generate EOF and
 417                  * not delay this indefinitely by because we
 418                  * keep an unused copy of stdin around. */
 419                 fd = open("/dev/tty", O_WRONLY);
 420                 if (fd < 0) {
 421                         log_error_errno(errno, "Failed to open /dev/tty: %m");
 422                         _exit(EXIT_FAILURE);
 423                 }
 424
 425                 if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) {
 426                         log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
 427                         _exit(EXIT_FAILURE);
 428                 }
 429
 430                 if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) {
 431                         log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
 432                         _exit(EXIT_FAILURE);
 433                 }
 434
 435                 if (fd > STDERR_FILENO)
 436                         close(fd);
 437         }
 438
 439         /* Count arguments */
 440         va_start(ap, path);
 441         for (n = 0; va_arg(ap, char*); n++)
 442                 ;
 443         va_end(ap);
 444
 445         /* Allocate strv */
 446         l = alloca(sizeof(char *) * (n + 1));
 447
 448         /* Fill in arguments */
 449         va_start(ap, path);
 450         for (i = 0; i <= n; i++)
 451                 l[i] = va_arg(ap, char*);
 452         va_end(ap);
 453
 454         execv(path, l);
 455         _exit(EXIT_FAILURE);
 456 }
 457
 458 bool in_initrd(void) {
 459         struct statfs s;
 460
 461         if (saved_in_initrd >= 0)
 462                 return saved_in_initrd;
 463
 464         /* We make two checks here:
 465          *
 466          * 1. the flag file /etc/initrd-release must exist
 467          * 2. the root file system must be a memory file system
 468          *
 469          * The second check is extra paranoia, since misdetecting an
 470          * initrd can have bad consequences due the initrd
 471          * emptying when transititioning to the main systemd.
 472          */
 473
 474         saved_in_initrd = access("/etc/initrd-release", F_OK) >= 0 &&
 475                           statfs("/", &s) >= 0 &&
 476                           is_temporary_fs(&s);
 477
 478         return saved_in_initrd;
 479 }
 480
 481 void in_initrd_force(bool value) {
 482         saved_in_initrd = value;
 483 }
 484
 485 /* hey glibc, APIs with callbacks without a user pointer are so useless */
 486 void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
 487                  int (*compar) (const void *, const void *, void *), void *arg) {
 488         size_t l, u, idx;
 489         const void *p;
 490         int comparison;
 491
 492         l = 0;
 493         u = nmemb;
 494         while (l < u) {
 495                 idx = (l + u) / 2;
 496                 p = (void *)(((const char *) base) + (idx * size));
 497                 comparison = compar(key, p, arg);
 498                 if (comparison < 0)
 499                         u = idx;
 500                 else if (comparison > 0)
 501                         l = idx + 1;
 502                 else
 503                         return (void *)p;
 504         }
 505         return NULL;
 506 }
 507
 508 int on_ac_power(void) {
 509         bool found_offline = false, found_online = false;
 510         _cleanup_closedir_ DIR *d = NULL;
 511
 512         d = opendir("/sys/class/power_supply");
 513         if (!d)
 514                 return errno == ENOENT ? true : -errno;
 515
 516         for (;;) {
 517                 struct dirent *de;
 518                 _cleanup_close_ int fd = -1, device = -1;
 519                 char contents[6];
 520                 ssize_t n;
 521
 522                 errno = 0;
 523                 de = readdir(d);
 524                 if (!de && errno > 0)
 525                         return -errno;
 526
 527                 if (!de)
 528                         break;
 529
 530                 if (hidden_or_backup_file(de->d_name))
 531                         continue;
 532
 533                 device = openat(dirfd(d), de->d_name, O_DIRECTORY|O_RDONLY|O_CLOEXEC|O_NOCTTY);
 534                 if (device < 0) {
 535                         if (errno == ENOENT || errno == ENOTDIR)
 536                                 continue;
 537
 538                         return -errno;
 539                 }
 540
 541                 fd = openat(device, "type", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 542                 if (fd < 0) {
 543                         if (errno == ENOENT)
 544                                 continue;
 545
 546                         return -errno;
 547                 }
 548
 549                 n = read(fd, contents, sizeof(contents));
 550                 if (n < 0)
 551                         return -errno;
 552
 553                 if (n != 6 || memcmp(contents, "Mains\n", 6))
 554                         continue;
 555
 556                 safe_close(fd);
 557                 fd = openat(device, "online", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 558                 if (fd < 0) {
 559                         if (errno == ENOENT)
 560                                 continue;
 561
 562                         return -errno;
 563                 }
 564
 565                 n = read(fd, contents, sizeof(contents));
 566                 if (n < 0)
 567                         return -errno;
 568
 569                 if (n != 2 || contents[1] != '\n')
 570                         return -EIO;
 571
 572                 if (contents[0] == '1') {
 573                         found_online = true;
 574                         break;
 575                 } else if (contents[0] == '0')
 576                         found_offline = true;
 577                 else
 578                         return -EIO;
 579         }
 580
 581         return found_online || !found_offline;
 582 }
 583
 584 int container_get_leader(const char *machine, pid_t *pid) {
 585         _cleanup_free_ char *s = NULL, *class = NULL;
 586         const char *p;
 587         pid_t leader;
 588         int r;
 589
 590         assert(machine);
 591         assert(pid);
 592
 593         if (!machine_name_is_valid(machine))
 594                 return -EINVAL;
 595
 596         p = strjoina("/run/systemd/machines/", machine);
 597         r = parse_env_file(p, NEWLINE, "LEADER", &s, "CLASS", &class, NULL);
 598         if (r == -ENOENT)
 599                 return -EHOSTDOWN;
 600         if (r < 0)
 601                 return r;
 602         if (!s)
 603                 return -EIO;
 604
 605         if (!streq_ptr(class, "container"))
 606                 return -EIO;
 607
 608         r = parse_pid(s, &leader);
 609         if (r < 0)
 610                 return r;
 611         if (leader <= 1)
 612                 return -EIO;
 613
 614         *pid = leader;
 615         return 0;
 616 }
 617
 618 int namespace_open(pid_t pid, int *pidns_fd, int *mntns_fd, int *netns_fd, int *userns_fd, int *root_fd) {
 619         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, netnsfd = -1, usernsfd = -1;
 620         int rfd = -1;
 621
 622         assert(pid >= 0);
 623
 624         if (mntns_fd) {
 625                 const char *mntns;
 626
 627                 mntns = procfs_file_alloca(pid, "ns/mnt");
 628                 mntnsfd = open(mntns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 629                 if (mntnsfd < 0)
 630                         return -errno;
 631         }
 632
 633         if (pidns_fd) {
 634                 const char *pidns;
 635
 636                 pidns = procfs_file_alloca(pid, "ns/pid");
 637                 pidnsfd = open(pidns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 638                 if (pidnsfd < 0)
 639                         return -errno;
 640         }
 641
 642         if (netns_fd) {
 643                 const char *netns;
 644
 645                 netns = procfs_file_alloca(pid, "ns/net");
 646                 netnsfd = open(netns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 647                 if (netnsfd < 0)
 648                         return -errno;
 649         }
 650
 651         if (userns_fd) {
 652                 const char *userns;
 653
 654                 userns = procfs_file_alloca(pid, "ns/user");
 655                 usernsfd = open(userns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 656                 if (usernsfd < 0 && errno != ENOENT)
 657                         return -errno;
 658         }
 659
 660         if (root_fd) {
 661                 const char *root;
 662
 663                 root = procfs_file_alloca(pid, "root");
 664                 rfd = open(root, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
 665                 if (rfd < 0)
 666                         return -errno;
 667         }
 668
 669         if (pidns_fd)
 670                 *pidns_fd = pidnsfd;
 671
 672         if (mntns_fd)
 673                 *mntns_fd = mntnsfd;
 674
 675         if (netns_fd)
 676                 *netns_fd = netnsfd;
 677
 678         if (userns_fd)
 679                 *userns_fd = usernsfd;
 680
 681         if (root_fd)
 682                 *root_fd = rfd;
 683
 684         pidnsfd = mntnsfd = netnsfd = usernsfd = -1;
 685
 686         return 0;
 687 }
 688
 689 int namespace_enter(int pidns_fd, int mntns_fd, int netns_fd, int userns_fd, int root_fd) {
 690         if (userns_fd >= 0) {
 691                 /* Can't setns to your own userns, since then you could
 692                  * escalate from non-root to root in your own namespace, so
 693                  * check if namespaces equal before attempting to enter. */
 694                 _cleanup_free_ char *userns_fd_path = NULL;
 695                 int r;
 696                 if (asprintf(&userns_fd_path, "/proc/self/fd/%d", userns_fd) < 0)
 697                         return -ENOMEM;
 698
 699                 r = files_same(userns_fd_path, "/proc/self/ns/user");
 700                 if (r < 0)
 701                         return r;
 702                 if (r)
 703                         userns_fd = -1;
 704         }
 705
 706         if (pidns_fd >= 0)
 707                 if (setns(pidns_fd, CLONE_NEWPID) < 0)
 708                         return -errno;
 709
 710         if (mntns_fd >= 0)
 711                 if (setns(mntns_fd, CLONE_NEWNS) < 0)
 712                         return -errno;
 713
 714         if (netns_fd >= 0)
 715                 if (setns(netns_fd, CLONE_NEWNET) < 0)
 716                         return -errno;
 717
 718         if (userns_fd >= 0)
 719                 if (setns(userns_fd, CLONE_NEWUSER) < 0)
 720                         return -errno;
 721
 722         if (root_fd >= 0) {
 723                 if (fchdir(root_fd) < 0)
 724                         return -errno;
 725
 726                 if (chroot(".") < 0)
 727                         return -errno;
 728         }
 729
 730         return reset_uid_gid();
 731 }
 732
 733 uint64_t physical_memory(void) {
 734         _cleanup_free_ char *root = NULL, *value = NULL;
 735         uint64_t mem, lim;
 736         size_t ps;
 737         long sc;
 738
 739         /* We return this as uint64_t in case we are running as 32bit process on a 64bit kernel with huge amounts of
 740          * memory.
 741          *
 742          * In order to support containers nicely that have a configured memory limit we'll take the minimum of the
 743          * physically reported amount of memory and the limit configured for the root cgroup, if there is any. */
 744
 745         sc = sysconf(_SC_PHYS_PAGES);
 746         assert(sc > 0);
 747
 748         ps = page_size();
 749         mem = (uint64_t) sc * (uint64_t) ps;
 750
 751         if (cg_get_root_path(&root) < 0)
 752                 return mem;
 753
 754         if (cg_get_attribute("memory", root, "memory.limit_in_bytes", &value))
 755                 return mem;
 756
 757         if (safe_atou64(value, &lim) < 0)
 758                 return mem;
 759
 760         /* Make sure the limit is a multiple of our own page size */
 761         lim /= ps;
 762         lim *= ps;
 763
 764         return MIN(mem, lim);
 765 }
 766
 767 uint64_t physical_memory_scale(uint64_t v, uint64_t max) {
 768         uint64_t p, m, ps, r;
 769
 770         assert(max > 0);
 771
 772         /* Returns the physical memory size, multiplied by v divided by max. Returns UINT64_MAX on overflow. On success
 773          * the result is a multiple of the page size (rounds down). */
 774
 775         ps = page_size();
 776         assert(ps > 0);
 777
 778         p = physical_memory() / ps;
 779         assert(p > 0);
 780
 781         m = p * v;
 782         if (m / p != v)
 783                 return UINT64_MAX;
 784
 785         m /= max;
 786
 787         r = m * ps;
 788         if (r / ps != m)
 789                 return UINT64_MAX;
 790
 791         return r;
 792 }
 793
 794 uint64_t system_tasks_max(void) {
 795
 796 #if SIZEOF_PID_T == 4
 797 #define TASKS_MAX ((uint64_t) (INT32_MAX-1))
 798 #elif SIZEOF_PID_T == 2
 799 #define TASKS_MAX ((uint64_t) (INT16_MAX-1))
 800 #else
 801 #error "Unknown pid_t size"
 802 #endif
 803
 804         _cleanup_free_ char *value = NULL, *root = NULL;
 805         uint64_t a = TASKS_MAX, b = TASKS_MAX;
 806
 807         /* Determine the maximum number of tasks that may run on this system. We check three sources to determine this
 808          * limit:
 809          *
 810          * a) the maximum value for the pid_t type
 811          * b) the cgroups pids_max attribute for the system
 812          * c) the kernel's configure maximum PID value
 813          *
 814          * And then pick the smallest of the three */
 815
 816         if (read_one_line_file("/proc/sys/kernel/pid_max", &value) >= 0)
 817                 (void) safe_atou64(value, &a);
 818
 819         if (cg_get_root_path(&root) >= 0) {
 820                 value = mfree(value);
 821
 822                 if (cg_get_attribute("pids", root, "pids.max", &value) >= 0)
 823                         (void) safe_atou64(value, &b);
 824         }
 825
 826         return MIN3(TASKS_MAX,
 827                     a <= 0 ? TASKS_MAX : a,
 828                     b <= 0 ? TASKS_MAX : b);
 829 }
 830
 831 uint64_t system_tasks_max_scale(uint64_t v, uint64_t max) {
 832         uint64_t t, m;
 833
 834         assert(max > 0);
 835
 836         /* Multiply the system's task value by the fraction v/max. Hence, if max==100 this calculates percentages
 837          * relative to the system's maximum number of tasks. Returns UINT64_MAX on overflow. */
 838
 839         t = system_tasks_max();
 840         assert(t > 0);
 841
 842         m = t * v;
 843         if (m / t != v) /* overflow? */
 844                 return UINT64_MAX;
 845
 846         return m / max;
 847 }
 848
 849 int update_reboot_parameter_and_warn(const char *param) {
 850         int r;
 851
 852         if (isempty(param)) {
 853                 if (unlink("/run/systemd/reboot-param") < 0) {
 854                         if (errno == ENOENT)
 855                                 return 0;
 856
 857                         return log_warning_errno(errno, "Failed to unlink reboot parameter file: %m");
 858                 }
 859
 860                 return 0;
 861         }
 862
 863         RUN_WITH_UMASK(0022) {
 864                 r = write_string_file("/run/systemd/reboot-param", param, WRITE_STRING_FILE_CREATE);
 865                 if (r < 0)
 866                         return log_warning_errno(r, "Failed to write reboot parameter file: %m");
 867         }
 868
 869         return 0;
 870 }
 871
 872 int version(void) {
 873         puts(PACKAGE_STRING "\n"
 874              SYSTEMD_FEATURES);
 875         return 0;
 876 }