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