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 "def.h"
  40 #include "dirent-util.h"
  41 #include "fd-util.h"
  42 #include "fileio.h"
  43 #include "formats-util.h"
  44 #include "hashmap.h"
  45 #include "hostname-util.h"
  46 #include "log.h"
  47 #include "macro.h"
  48 #include "missing.h"
  49 #include "parse-util.h"
  50 #include "path-util.h"
  51 #include "process-util.h"
  52 #include "set.h"
  53 #include "signal-util.h"
  54 #include "stat-util.h"
  55 #include "string-util.h"
  56 #include "strv.h"
  57 #include "time-util.h"
  58 #include "user-util.h"
  59 #include "util.h"
  60
  61 /* Put this test here for a lack of better place */
  62 assert_cc(EAGAIN == EWOULDBLOCK);
  63
  64 int saved_argc = 0;
  65 char **saved_argv = NULL;
  66
  67 size_t page_size(void) {
  68         static thread_local size_t pgsz = 0;
  69         long r;
  70
  71         if (_likely_(pgsz > 0))
  72                 return pgsz;
  73
  74         r = sysconf(_SC_PAGESIZE);
  75         assert(r > 0);
  76
  77         pgsz = (size_t) r;
  78         return pgsz;
  79 }
  80
  81 static int do_execute(char **directories, usec_t timeout, char *argv[]) {
  82         _cleanup_hashmap_free_free_ Hashmap *pids = NULL;
  83         _cleanup_set_free_free_ Set *seen = NULL;
  84         char **directory;
  85
  86         /* We fork this all off from a child process so that we can
  87          * somewhat cleanly make use of SIGALRM to set a time limit */
  88
  89         (void) reset_all_signal_handlers();
  90         (void) reset_signal_mask();
  91
  92         assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
  93
  94         pids = hashmap_new(NULL);
  95         if (!pids)
  96                 return log_oom();
  97
  98         seen = set_new(&string_hash_ops);
  99         if (!seen)
 100                 return log_oom();
 101
 102         STRV_FOREACH(directory, directories) {
 103                 _cleanup_closedir_ DIR *d;
 104                 struct dirent *de;
 105
 106                 d = opendir(*directory);
 107                 if (!d) {
 108                         if (errno == ENOENT)
 109                                 continue;
 110
 111                         return log_error_errno(errno, "Failed to open directory %s: %m", *directory);
 112                 }
 113
 114                 FOREACH_DIRENT(de, d, break) {
 115                         _cleanup_free_ char *path = NULL;
 116                         pid_t pid;
 117                         int r;
 118
 119                         if (!dirent_is_file(de))
 120                                 continue;
 121
 122                         if (set_contains(seen, de->d_name)) {
 123                                 log_debug("%1$s/%2$s skipped (%2$s was already seen).", *directory, de->d_name);
 124                                 continue;
 125                         }
 126
 127                         r = set_put_strdup(seen, de->d_name);
 128                         if (r < 0)
 129                                 return log_oom();
 130
 131                         path = strjoin(*directory, "/", de->d_name, NULL);
 132                         if (!path)
 133                                 return log_oom();
 134
 135                         if (null_or_empty_path(path)) {
 136                                 log_debug("%s is empty (a mask).", path);
 137                                 continue;
 138                         }
 139
 140                         pid = fork();
 141                         if (pid < 0) {
 142                                 log_error_errno(errno, "Failed to fork: %m");
 143                                 continue;
 144                         } else if (pid == 0) {
 145                                 char *_argv[2];
 146
 147                                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
 148
 149                                 if (!argv) {
 150                                         _argv[0] = path;
 151                                         _argv[1] = NULL;
 152                                         argv = _argv;
 153                                 } else
 154                                         argv[0] = path;
 155
 156                                 execv(path, argv);
 157                                 return log_error_errno(errno, "Failed to execute %s: %m", path);
 158                         }
 159
 160                         log_debug("Spawned %s as " PID_FMT ".", path, pid);
 161
 162                         r = hashmap_put(pids, PID_TO_PTR(pid), path);
 163                         if (r < 0)
 164                                 return log_oom();
 165                         path = NULL;
 166                 }
 167         }
 168
 169         /* Abort execution of this process after the timout. We simply
 170          * rely on SIGALRM as default action terminating the process,
 171          * and turn on alarm(). */
 172
 173         if (timeout != USEC_INFINITY)
 174                 alarm((timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
 175
 176         while (!hashmap_isempty(pids)) {
 177                 _cleanup_free_ char *path = NULL;
 178                 pid_t pid;
 179
 180                 pid = PTR_TO_PID(hashmap_first_key(pids));
 181                 assert(pid > 0);
 182
 183                 path = hashmap_remove(pids, PID_TO_PTR(pid));
 184                 assert(path);
 185
 186                 wait_for_terminate_and_warn(path, pid, true);
 187         }
 188
 189         return 0;
 190 }
 191
 192 void execute_directories(const char* const* directories, usec_t timeout, char *argv[]) {
 193         pid_t executor_pid;
 194         int r;
 195         char *name;
 196         char **dirs = (char**) directories;
 197
 198         assert(!strv_isempty(dirs));
 199
 200         name = basename(dirs[0]);
 201         assert(!isempty(name));
 202
 203         /* Executes all binaries in the directories in parallel and waits
 204          * for them to finish. Optionally a timeout is applied. If a file
 205          * with the same name exists in more than one directory, the
 206          * earliest one wins. */
 207
 208         executor_pid = fork();
 209         if (executor_pid < 0) {
 210                 log_error_errno(errno, "Failed to fork: %m");
 211                 return;
 212
 213         } else if (executor_pid == 0) {
 214                 r = do_execute(dirs, timeout, argv);
 215                 _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
 216         }
 217
 218         wait_for_terminate_and_warn(name, executor_pid, true);
 219 }
 220
 221 bool plymouth_running(void) {
 222         return access("/run/plymouth/pid", F_OK) >= 0;
 223 }
 224
 225 bool display_is_local(const char *display) {
 226         assert(display);
 227
 228         return
 229                 display[0] == ':' &&
 230                 display[1] >= '0' &&
 231                 display[1] <= '9';
 232 }
 233
 234 int socket_from_display(const char *display, char **path) {
 235         size_t k;
 236         char *f, *c;
 237
 238         assert(display);
 239         assert(path);
 240
 241         if (!display_is_local(display))
 242                 return -EINVAL;
 243
 244         k = strspn(display+1, "0123456789");
 245
 246         f = new(char, strlen("/tmp/.X11-unix/X") + k + 1);
 247         if (!f)
 248                 return -ENOMEM;
 249
 250         c = stpcpy(f, "/tmp/.X11-unix/X");
 251         memcpy(c, display+1, k);
 252         c[k] = 0;
 253
 254         *path = f;
 255
 256         return 0;
 257 }
 258
 259 int block_get_whole_disk(dev_t d, dev_t *ret) {
 260         char *p, *s;
 261         int r;
 262         unsigned n, m;
 263
 264         assert(ret);
 265
 266         /* If it has a queue this is good enough for us */
 267         if (asprintf(&p, "/sys/dev/block/%u:%u/queue", major(d), minor(d)) < 0)
 268                 return -ENOMEM;
 269
 270         r = access(p, F_OK);
 271         free(p);
 272
 273         if (r >= 0) {
 274                 *ret = d;
 275                 return 0;
 276         }
 277
 278         /* If it is a partition find the originating device */
 279         if (asprintf(&p, "/sys/dev/block/%u:%u/partition", major(d), minor(d)) < 0)
 280                 return -ENOMEM;
 281
 282         r = access(p, F_OK);
 283         free(p);
 284
 285         if (r < 0)
 286                 return -ENOENT;
 287
 288         /* Get parent dev_t */
 289         if (asprintf(&p, "/sys/dev/block/%u:%u/../dev", major(d), minor(d)) < 0)
 290                 return -ENOMEM;
 291
 292         r = read_one_line_file(p, &s);
 293         free(p);
 294
 295         if (r < 0)
 296                 return r;
 297
 298         r = sscanf(s, "%u:%u", &m, &n);
 299         free(s);
 300
 301         if (r != 2)
 302                 return -EINVAL;
 303
 304         /* Only return this if it is really good enough for us. */
 305         if (asprintf(&p, "/sys/dev/block/%u:%u/queue", m, n) < 0)
 306                 return -ENOMEM;
 307
 308         r = access(p, F_OK);
 309         free(p);
 310
 311         if (r >= 0) {
 312                 *ret = makedev(m, n);
 313                 return 0;
 314         }
 315
 316         return -ENOENT;
 317 }
 318
 319 bool kexec_loaded(void) {
 320        bool loaded = false;
 321        char *s;
 322
 323        if (read_one_line_file("/sys/kernel/kexec_loaded", &s) >= 0) {
 324                if (s[0] == '1')
 325                        loaded = true;
 326                free(s);
 327        }
 328        return loaded;
 329 }
 330
 331 int prot_from_flags(int flags) {
 332
 333         switch (flags & O_ACCMODE) {
 334
 335         case O_RDONLY:
 336                 return PROT_READ;
 337
 338         case O_WRONLY:
 339                 return PROT_WRITE;
 340
 341         case O_RDWR:
 342                 return PROT_READ|PROT_WRITE;
 343
 344         default:
 345                 return -EINVAL;
 346         }
 347 }
 348
 349 int fork_agent(pid_t *pid, const int except[], unsigned n_except, const char *path, ...) {
 350         bool stdout_is_tty, stderr_is_tty;
 351         pid_t parent_pid, agent_pid;
 352         sigset_t ss, saved_ss;
 353         unsigned n, i;
 354         va_list ap;
 355         char **l;
 356
 357         assert(pid);
 358         assert(path);
 359
 360         /* Spawns a temporary TTY agent, making sure it goes away when
 361          * we go away */
 362
 363         parent_pid = getpid();
 364
 365         /* First we temporarily block all signals, so that the new
 366          * child has them blocked initially. This way, we can be sure
 367          * that SIGTERMs are not lost we might send to the agent. */
 368         assert_se(sigfillset(&ss) >= 0);
 369         assert_se(sigprocmask(SIG_SETMASK, &ss, &saved_ss) >= 0);
 370
 371         agent_pid = fork();
 372         if (agent_pid < 0) {
 373                 assert_se(sigprocmask(SIG_SETMASK, &saved_ss, NULL) >= 0);
 374                 return -errno;
 375         }
 376
 377         if (agent_pid != 0) {
 378                 assert_se(sigprocmask(SIG_SETMASK, &saved_ss, NULL) >= 0);
 379                 *pid = agent_pid;
 380                 return 0;
 381         }
 382
 383         /* In the child:
 384          *
 385          * Make sure the agent goes away when the parent dies */
 386         if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
 387                 _exit(EXIT_FAILURE);
 388
 389         /* Make sure we actually can kill the agent, if we need to, in
 390          * case somebody invoked us from a shell script that trapped
 391          * SIGTERM or so... */
 392         (void) reset_all_signal_handlers();
 393         (void) reset_signal_mask();
 394
 395         /* Check whether our parent died before we were able
 396          * to set the death signal and unblock the signals */
 397         if (getppid() != parent_pid)
 398                 _exit(EXIT_SUCCESS);
 399
 400         /* Don't leak fds to the agent */
 401         close_all_fds(except, n_except);
 402
 403         stdout_is_tty = isatty(STDOUT_FILENO);
 404         stderr_is_tty = isatty(STDERR_FILENO);
 405
 406         if (!stdout_is_tty || !stderr_is_tty) {
 407                 int fd;
 408
 409                 /* Detach from stdout/stderr. and reopen
 410                  * /dev/tty for them. This is important to
 411                  * ensure that when systemctl is started via
 412                  * popen() or a similar call that expects to
 413                  * read EOF we actually do generate EOF and
 414                  * not delay this indefinitely by because we
 415                  * keep an unused copy of stdin around. */
 416                 fd = open("/dev/tty", O_WRONLY);
 417                 if (fd < 0) {
 418                         log_error_errno(errno, "Failed to open /dev/tty: %m");
 419                         _exit(EXIT_FAILURE);
 420                 }
 421
 422                 if (!stdout_is_tty)
 423                         dup2(fd, STDOUT_FILENO);
 424
 425                 if (!stderr_is_tty)
 426                         dup2(fd, STDERR_FILENO);
 427
 428                 if (fd > 2)
 429                         close(fd);
 430         }
 431
 432         /* Count arguments */
 433         va_start(ap, path);
 434         for (n = 0; va_arg(ap, char*); n++)
 435                 ;
 436         va_end(ap);
 437
 438         /* Allocate strv */
 439         l = alloca(sizeof(char *) * (n + 1));
 440
 441         /* Fill in arguments */
 442         va_start(ap, path);
 443         for (i = 0; i <= n; i++)
 444                 l[i] = va_arg(ap, char*);
 445         va_end(ap);
 446
 447         execv(path, l);
 448         _exit(EXIT_FAILURE);
 449 }
 450
 451 bool in_initrd(void) {
 452         static int saved = -1;
 453         struct statfs s;
 454
 455         if (saved >= 0)
 456                 return saved;
 457
 458         /* We make two checks here:
 459          *
 460          * 1. the flag file /etc/initrd-release must exist
 461          * 2. the root file system must be a memory file system
 462          *
 463          * The second check is extra paranoia, since misdetecting an
 464          * initrd can have bad bad consequences due the initrd
 465          * emptying when transititioning to the main systemd.
 466          */
 467
 468         saved = access("/etc/initrd-release", F_OK) >= 0 &&
 469                 statfs("/", &s) >= 0 &&
 470                 is_temporary_fs(&s);
 471
 472         return saved;
 473 }
 474
 475 /* hey glibc, APIs with callbacks without a user pointer are so useless */
 476 void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
 477                  int (*compar) (const void *, const void *, void *), void *arg) {
 478         size_t l, u, idx;
 479         const void *p;
 480         int comparison;
 481
 482         l = 0;
 483         u = nmemb;
 484         while (l < u) {
 485                 idx = (l + u) / 2;
 486                 p = (void *)(((const char *) base) + (idx * size));
 487                 comparison = compar(key, p, arg);
 488                 if (comparison < 0)
 489                         u = idx;
 490                 else if (comparison > 0)
 491                         l = idx + 1;
 492                 else
 493                         return (void *)p;
 494         }
 495         return NULL;
 496 }
 497
 498 int on_ac_power(void) {
 499         bool found_offline = false, found_online = false;
 500         _cleanup_closedir_ DIR *d = NULL;
 501
 502         d = opendir("/sys/class/power_supply");
 503         if (!d)
 504                 return errno == ENOENT ? true : -errno;
 505
 506         for (;;) {
 507                 struct dirent *de;
 508                 _cleanup_close_ int fd = -1, device = -1;
 509                 char contents[6];
 510                 ssize_t n;
 511
 512                 errno = 0;
 513                 de = readdir(d);
 514                 if (!de && errno > 0)
 515                         return -errno;
 516
 517                 if (!de)
 518                         break;
 519
 520                 if (hidden_file(de->d_name))
 521                         continue;
 522
 523                 device = openat(dirfd(d), de->d_name, O_DIRECTORY|O_RDONLY|O_CLOEXEC|O_NOCTTY);
 524                 if (device < 0) {
 525                         if (errno == ENOENT || errno == ENOTDIR)
 526                                 continue;
 527
 528                         return -errno;
 529                 }
 530
 531                 fd = openat(device, "type", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 532                 if (fd < 0) {
 533                         if (errno == ENOENT)
 534                                 continue;
 535
 536                         return -errno;
 537                 }
 538
 539                 n = read(fd, contents, sizeof(contents));
 540                 if (n < 0)
 541                         return -errno;
 542
 543                 if (n != 6 || memcmp(contents, "Mains\n", 6))
 544                         continue;
 545
 546                 safe_close(fd);
 547                 fd = openat(device, "online", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 548                 if (fd < 0) {
 549                         if (errno == ENOENT)
 550                                 continue;
 551
 552                         return -errno;
 553                 }
 554
 555                 n = read(fd, contents, sizeof(contents));
 556                 if (n < 0)
 557                         return -errno;
 558
 559                 if (n != 2 || contents[1] != '\n')
 560                         return -EIO;
 561
 562                 if (contents[0] == '1') {
 563                         found_online = true;
 564                         break;
 565                 } else if (contents[0] == '0')
 566                         found_offline = true;
 567                 else
 568                         return -EIO;
 569         }
 570
 571         return found_online || !found_offline;
 572 }
 573
 574 bool id128_is_valid(const char *s) {
 575         size_t i, l;
 576
 577         l = strlen(s);
 578         if (l == 32) {
 579
 580                 /* Simple formatted 128bit hex string */
 581
 582                 for (i = 0; i < l; i++) {
 583                         char c = s[i];
 584
 585                         if (!(c >= '0' && c <= '9') &&
 586                             !(c >= 'a' && c <= 'z') &&
 587                             !(c >= 'A' && c <= 'Z'))
 588                                 return false;
 589                 }
 590
 591         } else if (l == 36) {
 592
 593                 /* Formatted UUID */
 594
 595                 for (i = 0; i < l; i++) {
 596                         char c = s[i];
 597
 598                         if ((i == 8 || i == 13 || i == 18 || i == 23)) {
 599                                 if (c != '-')
 600                                         return false;
 601                         } else {
 602                                 if (!(c >= '0' && c <= '9') &&
 603                                     !(c >= 'a' && c <= 'z') &&
 604                                     !(c >= 'A' && c <= 'Z'))
 605                                         return false;
 606                         }
 607                 }
 608
 609         } else
 610                 return false;
 611
 612         return true;
 613 }
 614
 615 int container_get_leader(const char *machine, pid_t *pid) {
 616         _cleanup_free_ char *s = NULL, *class = NULL;
 617         const char *p;
 618         pid_t leader;
 619         int r;
 620
 621         assert(machine);
 622         assert(pid);
 623
 624         if (!machine_name_is_valid(machine))
 625                 return -EINVAL;
 626
 627         p = strjoina("/run/systemd/machines/", machine);
 628         r = parse_env_file(p, NEWLINE, "LEADER", &s, "CLASS", &class, NULL);
 629         if (r == -ENOENT)
 630                 return -EHOSTDOWN;
 631         if (r < 0)
 632                 return r;
 633         if (!s)
 634                 return -EIO;
 635
 636         if (!streq_ptr(class, "container"))
 637                 return -EIO;
 638
 639         r = parse_pid(s, &leader);
 640         if (r < 0)
 641                 return r;
 642         if (leader <= 1)
 643                 return -EIO;
 644
 645         *pid = leader;
 646         return 0;
 647 }
 648
 649 int namespace_open(pid_t pid, int *pidns_fd, int *mntns_fd, int *netns_fd, int *userns_fd, int *root_fd) {
 650         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, netnsfd = -1, usernsfd = -1;
 651         int rfd = -1;
 652
 653         assert(pid >= 0);
 654
 655         if (mntns_fd) {
 656                 const char *mntns;
 657
 658                 mntns = procfs_file_alloca(pid, "ns/mnt");
 659                 mntnsfd = open(mntns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 660                 if (mntnsfd < 0)
 661                         return -errno;
 662         }
 663
 664         if (pidns_fd) {
 665                 const char *pidns;
 666
 667                 pidns = procfs_file_alloca(pid, "ns/pid");
 668                 pidnsfd = open(pidns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 669                 if (pidnsfd < 0)
 670                         return -errno;
 671         }
 672
 673         if (netns_fd) {
 674                 const char *netns;
 675
 676                 netns = procfs_file_alloca(pid, "ns/net");
 677                 netnsfd = open(netns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 678                 if (netnsfd < 0)
 679                         return -errno;
 680         }
 681
 682         if (userns_fd) {
 683                 const char *userns;
 684
 685                 userns = procfs_file_alloca(pid, "ns/user");
 686                 usernsfd = open(userns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 687                 if (usernsfd < 0 && errno != ENOENT)
 688                         return -errno;
 689         }
 690
 691         if (root_fd) {
 692                 const char *root;
 693
 694                 root = procfs_file_alloca(pid, "root");
 695                 rfd = open(root, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
 696                 if (rfd < 0)
 697                         return -errno;
 698         }
 699
 700         if (pidns_fd)
 701                 *pidns_fd = pidnsfd;
 702
 703         if (mntns_fd)
 704                 *mntns_fd = mntnsfd;
 705
 706         if (netns_fd)
 707                 *netns_fd = netnsfd;
 708
 709         if (userns_fd)
 710                 *userns_fd = usernsfd;
 711
 712         if (root_fd)
 713                 *root_fd = rfd;
 714
 715         pidnsfd = mntnsfd = netnsfd = usernsfd = -1;
 716
 717         return 0;
 718 }
 719
 720 int namespace_enter(int pidns_fd, int mntns_fd, int netns_fd, int userns_fd, int root_fd) {
 721         if (userns_fd >= 0) {
 722                 /* Can't setns to your own userns, since then you could
 723                  * escalate from non-root to root in your own namespace, so
 724                  * check if namespaces equal before attempting to enter. */
 725                 _cleanup_free_ char *userns_fd_path = NULL;
 726                 int r;
 727                 if (asprintf(&userns_fd_path, "/proc/self/fd/%d", userns_fd) < 0)
 728                         return -ENOMEM;
 729
 730                 r = files_same(userns_fd_path, "/proc/self/ns/user");
 731                 if (r < 0)
 732                         return r;
 733                 if (r)
 734                         userns_fd = -1;
 735         }
 736
 737         if (pidns_fd >= 0)
 738                 if (setns(pidns_fd, CLONE_NEWPID) < 0)
 739                         return -errno;
 740
 741         if (mntns_fd >= 0)
 742                 if (setns(mntns_fd, CLONE_NEWNS) < 0)
 743                         return -errno;
 744
 745         if (netns_fd >= 0)
 746                 if (setns(netns_fd, CLONE_NEWNET) < 0)
 747                         return -errno;
 748
 749         if (userns_fd >= 0)
 750                 if (setns(userns_fd, CLONE_NEWUSER) < 0)
 751                         return -errno;
 752
 753         if (root_fd >= 0) {
 754                 if (fchdir(root_fd) < 0)
 755                         return -errno;
 756
 757                 if (chroot(".") < 0)
 758                         return -errno;
 759         }
 760
 761         return reset_uid_gid();
 762 }
 763
 764 uint64_t physical_memory(void) {
 765         long mem;
 766
 767         /* We return this as uint64_t in case we are running as 32bit
 768          * process on a 64bit kernel with huge amounts of memory */
 769
 770         mem = sysconf(_SC_PHYS_PAGES);
 771         assert(mem > 0);
 772
 773         return (uint64_t) mem * (uint64_t) page_size();
 774 }
 775
 776 int update_reboot_param_file(const char *param) {
 777         int r = 0;
 778
 779         if (param) {
 780                 r = write_string_file(REBOOT_PARAM_FILE, param, WRITE_STRING_FILE_CREATE);
 781                 if (r < 0)
 782                         return log_error_errno(r, "Failed to write reboot param to "REBOOT_PARAM_FILE": %m");
 783         } else
 784                 (void) unlink(REBOOT_PARAM_FILE);
 785
 786         return 0;
 787 }
 788
 789 int version(void) {
 790         puts(PACKAGE_STRING "\n"
 791              SYSTEMD_FEATURES);
 792         return 0;
 793 }