src/basic/time-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 Lennart Poettering
   6 ***/
   7
   8 #include <errno.h>
   9 #include <limits.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <sys/mman.h>
  13 #include <sys/stat.h>
  14 #include <sys/time.h>
  15 #include <sys/timerfd.h>
  16 #include <sys/timex.h>
  17 #include <sys/types.h>
  18 #include <unistd.h>
  19
  20 #include "alloc-util.h"
  21 #include "fd-util.h"
  22 #include "fileio.h"
  23 #include "fs-util.h"
  24 //#include "io-util.h"
  25 #include "log.h"
  26 #include "macro.h"
  27 #include "parse-util.h"
  28 #include "path-util.h"
  29 //#include "process-util.h"
  30 //#include "stat-util.h"
  31 #include "string-util.h"
  32 #include "strv.h"
  33 #include "time-util.h"
  34
  35 static clockid_t map_clock_id(clockid_t c) {
  36
  37         /* Some more exotic archs (s390, ppc, …) lack the "ALARM" flavour of the clocks. Thus, clock_gettime() will
  38          * fail for them. Since they are essentially the same as their non-ALARM pendants (their only difference is
  39          * when timers are set on them), let's just map them accordingly. This way, we can get the correct time even on
  40          * those archs. */
  41
  42         switch (c) {
  43
  44         case CLOCK_BOOTTIME_ALARM:
  45                 return CLOCK_BOOTTIME;
  46
  47         case CLOCK_REALTIME_ALARM:
  48                 return CLOCK_REALTIME;
  49
  50         default:
  51                 return c;
  52         }
  53 }
  54
  55 usec_t now(clockid_t clock_id) {
  56         struct timespec ts;
  57
  58         assert_se(clock_gettime(map_clock_id(clock_id), &ts) == 0);
  59
  60         return timespec_load(&ts);
  61 }
  62
  63 #if 0 /// UNNEEDED by elogind
  64 nsec_t now_nsec(clockid_t clock_id) {
  65         struct timespec ts;
  66
  67         assert_se(clock_gettime(map_clock_id(clock_id), &ts) == 0);
  68
  69         return timespec_load_nsec(&ts);
  70 }
  71 #endif // 0
  72
  73 dual_timestamp* dual_timestamp_get(dual_timestamp *ts) {
  74         assert(ts);
  75
  76         ts->realtime = now(CLOCK_REALTIME);
  77         ts->monotonic = now(CLOCK_MONOTONIC);
  78
  79         return ts;
  80 }
  81
  82 triple_timestamp* triple_timestamp_get(triple_timestamp *ts) {
  83         assert(ts);
  84
  85         ts->realtime = now(CLOCK_REALTIME);
  86         ts->monotonic = now(CLOCK_MONOTONIC);
  87         ts->boottime = clock_boottime_supported() ? now(CLOCK_BOOTTIME) : USEC_INFINITY;
  88
  89         return ts;
  90 }
  91
  92 dual_timestamp* dual_timestamp_from_realtime(dual_timestamp *ts, usec_t u) {
  93         int64_t delta;
  94         assert(ts);
  95
  96         if (u == USEC_INFINITY || u <= 0) {
  97                 ts->realtime = ts->monotonic = u;
  98                 return ts;
  99         }
 100
 101         ts->realtime = u;
 102
 103         delta = (int64_t) now(CLOCK_REALTIME) - (int64_t) u;
 104         ts->monotonic = usec_sub_signed(now(CLOCK_MONOTONIC), delta);
 105
 106         return ts;
 107 }
 108
 109 #if 0 /// UNNEEDED by elogind
 110 triple_timestamp* triple_timestamp_from_realtime(triple_timestamp *ts, usec_t u) {
 111         int64_t delta;
 112
 113         assert(ts);
 114
 115         if (u == USEC_INFINITY || u <= 0) {
 116                 ts->realtime = ts->monotonic = ts->boottime = u;
 117                 return ts;
 118         }
 119
 120         ts->realtime = u;
 121         delta = (int64_t) now(CLOCK_REALTIME) - (int64_t) u;
 122         ts->monotonic = usec_sub_signed(now(CLOCK_MONOTONIC), delta);
 123         ts->boottime = clock_boottime_supported() ? usec_sub_signed(now(CLOCK_BOOTTIME), delta) : USEC_INFINITY;
 124
 125         return ts;
 126 }
 127
 128 dual_timestamp* dual_timestamp_from_monotonic(dual_timestamp *ts, usec_t u) {
 129         int64_t delta;
 130         assert(ts);
 131
 132         if (u == USEC_INFINITY) {
 133                 ts->realtime = ts->monotonic = USEC_INFINITY;
 134                 return ts;
 135         }
 136
 137         ts->monotonic = u;
 138         delta = (int64_t) now(CLOCK_MONOTONIC) - (int64_t) u;
 139         ts->realtime = usec_sub_signed(now(CLOCK_REALTIME), delta);
 140
 141         return ts;
 142 }
 143
 144 dual_timestamp* dual_timestamp_from_boottime_or_monotonic(dual_timestamp *ts, usec_t u) {
 145         int64_t delta;
 146
 147         if (u == USEC_INFINITY) {
 148                 ts->realtime = ts->monotonic = USEC_INFINITY;
 149                 return ts;
 150         }
 151
 152         dual_timestamp_get(ts);
 153         delta = (int64_t) now(clock_boottime_or_monotonic()) - (int64_t) u;
 154         ts->realtime = usec_sub_signed(ts->realtime, delta);
 155         ts->monotonic = usec_sub_signed(ts->monotonic, delta);
 156
 157         return ts;
 158 }
 159 #endif // 0
 160
 161 usec_t triple_timestamp_by_clock(triple_timestamp *ts, clockid_t clock) {
 162
 163         switch (clock) {
 164
 165         case CLOCK_REALTIME:
 166         case CLOCK_REALTIME_ALARM:
 167                 return ts->realtime;
 168
 169         case CLOCK_MONOTONIC:
 170                 return ts->monotonic;
 171
 172         case CLOCK_BOOTTIME:
 173         case CLOCK_BOOTTIME_ALARM:
 174                 return ts->boottime;
 175
 176         default:
 177                 return USEC_INFINITY;
 178         }
 179 }
 180
 181 usec_t timespec_load(const struct timespec *ts) {
 182         assert(ts);
 183
 184         if (ts->tv_sec < 0 || ts->tv_nsec < 0)
 185                 return USEC_INFINITY;
 186
 187         if ((usec_t) ts->tv_sec > (UINT64_MAX - (ts->tv_nsec / NSEC_PER_USEC)) / USEC_PER_SEC)
 188                 return USEC_INFINITY;
 189
 190         return
 191                 (usec_t) ts->tv_sec * USEC_PER_SEC +
 192                 (usec_t) ts->tv_nsec / NSEC_PER_USEC;
 193 }
 194
 195 #if 0 /// UNNEEDED by elogind
 196 nsec_t timespec_load_nsec(const struct timespec *ts) {
 197         assert(ts);
 198
 199         if (ts->tv_sec < 0 || ts->tv_nsec < 0)
 200                 return NSEC_INFINITY;
 201
 202         if ((nsec_t) ts->tv_sec >= (UINT64_MAX - ts->tv_nsec) / NSEC_PER_SEC)
 203                 return NSEC_INFINITY;
 204
 205         return (nsec_t) ts->tv_sec * NSEC_PER_SEC + (nsec_t) ts->tv_nsec;
 206 }
 207 #endif // 0
 208
 209 struct timespec *timespec_store(struct timespec *ts, usec_t u)  {
 210         assert(ts);
 211
 212         if (u == USEC_INFINITY ||
 213             u / USEC_PER_SEC >= TIME_T_MAX) {
 214                 ts->tv_sec = (time_t) -1;
 215                 ts->tv_nsec = (long) -1;
 216                 return ts;
 217         }
 218
 219         ts->tv_sec = (time_t) (u / USEC_PER_SEC);
 220         ts->tv_nsec = (long int) ((u % USEC_PER_SEC) * NSEC_PER_USEC);
 221
 222         return ts;
 223 }
 224
 225 usec_t timeval_load(const struct timeval *tv) {
 226         assert(tv);
 227
 228         if (tv->tv_sec < 0 || tv->tv_usec < 0)
 229                 return USEC_INFINITY;
 230
 231         if ((usec_t) tv->tv_sec > (UINT64_MAX - tv->tv_usec) / USEC_PER_SEC)
 232                 return USEC_INFINITY;
 233
 234         return
 235                 (usec_t) tv->tv_sec * USEC_PER_SEC +
 236                 (usec_t) tv->tv_usec;
 237 }
 238
 239 struct timeval *timeval_store(struct timeval *tv, usec_t u) {
 240         assert(tv);
 241
 242         if (u == USEC_INFINITY ||
 243             u / USEC_PER_SEC > TIME_T_MAX) {
 244                 tv->tv_sec = (time_t) -1;
 245                 tv->tv_usec = (suseconds_t) -1;
 246         } else {
 247                 tv->tv_sec = (time_t) (u / USEC_PER_SEC);
 248                 tv->tv_usec = (suseconds_t) (u % USEC_PER_SEC);
 249         }
 250
 251         return tv;
 252 }
 253
 254 static char *format_timestamp_internal(
 255                 char *buf,
 256                 size_t l,
 257                 usec_t t,
 258                 bool utc,
 259                 bool us) {
 260
 261         /* The weekdays in non-localized (English) form. We use this instead of the localized form, so that our
 262          * generated timestamps may be parsed with parse_timestamp(), and always read the same. */
 263         static const char * const weekdays[] = {
 264                 [0] = "Sun",
 265                 [1] = "Mon",
 266                 [2] = "Tue",
 267                 [3] = "Wed",
 268                 [4] = "Thu",
 269                 [5] = "Fri",
 270                 [6] = "Sat",
 271         };
 272
 273         struct tm tm;
 274         time_t sec;
 275         size_t n;
 276
 277         assert(buf);
 278
 279         if (l <
 280             3 +                  /* week day */
 281             1 + 10 +             /* space and date */
 282             1 + 8 +              /* space and time */
 283             (us ? 1 + 6 : 0) +   /* "." and microsecond part */
 284             1 + 1 +              /* space and shortest possible zone */
 285             1)
 286                 return NULL; /* Not enough space even for the shortest form. */
 287         if (t <= 0 || t == USEC_INFINITY)
 288                 return NULL; /* Timestamp is unset */
 289
 290         /* Let's not format times with years > 9999 */
 291         if (t > USEC_TIMESTAMP_FORMATTABLE_MAX)
 292                 return NULL;
 293
 294         sec = (time_t) (t / USEC_PER_SEC); /* Round down */
 295
 296         if (!localtime_or_gmtime_r(&sec, &tm, utc))
 297                 return NULL;
 298
 299         /* Start with the week day */
 300         assert((size_t) tm.tm_wday < ELEMENTSOF(weekdays));
 301         memcpy(buf, weekdays[tm.tm_wday], 4);
 302
 303         /* Add the main components */
 304         if (strftime(buf + 3, l - 3, " %Y-%m-%d %H:%M:%S", &tm) <= 0)
 305                 return NULL; /* Doesn't fit */
 306
 307         /* Append the microseconds part, if that's requested */
 308         if (us) {
 309                 n = strlen(buf);
 310                 if (n + 8 > l)
 311                         return NULL; /* Microseconds part doesn't fit. */
 312
 313                 sprintf(buf + n, ".%06"PRI_USEC, t % USEC_PER_SEC);
 314         }
 315
 316         /* Append the timezone */
 317         n = strlen(buf);
 318         if (utc) {
 319                 /* If this is UTC then let's explicitly use the "UTC" string here, because gmtime_r() normally uses the
 320                  * obsolete "GMT" instead. */
 321                 if (n + 5 > l)
 322                         return NULL; /* "UTC" doesn't fit. */
 323
 324                 strcpy(buf + n, " UTC");
 325
 326         } else if (!isempty(tm.tm_zone)) {
 327                 size_t tn;
 328
 329                 /* An explicit timezone is specified, let's use it, if it fits */
 330                 tn = strlen(tm.tm_zone);
 331                 if (n + 1 + tn + 1 > l) {
 332                         /* The full time zone does not fit in. Yuck. */
 333
 334                         if (n + 1 + _POSIX_TZNAME_MAX + 1 > l)
 335                                 return NULL; /* Not even enough space for the POSIX minimum (of 6)? In that case, complain that it doesn't fit */
 336
 337                         /* So the time zone doesn't fit in fully, but the caller passed enough space for the POSIX
 338                          * minimum time zone length. In this case suppress the timezone entirely, in order not to dump
 339                          * an overly long, hard to read string on the user. This should be safe, because the user will
 340                          * assume the local timezone anyway if none is shown. And so does parse_timestamp(). */
 341                 } else {
 342                         buf[n++] = ' ';
 343                         strcpy(buf + n, tm.tm_zone);
 344                 }
 345         }
 346
 347         return buf;
 348 }
 349
 350 char *format_timestamp(char *buf, size_t l, usec_t t) {
 351         return format_timestamp_internal(buf, l, t, false, false);
 352 }
 353
 354 #if 0 /// UNNEEDED by elogind
 355 char *format_timestamp_utc(char *buf, size_t l, usec_t t) {
 356         return format_timestamp_internal(buf, l, t, true, false);
 357 }
 358 #endif // 0
 359
 360 char *format_timestamp_us(char *buf, size_t l, usec_t t) {
 361         return format_timestamp_internal(buf, l, t, false, true);
 362 }
 363
 364 #if 0 /// UNNEEDED by elogind
 365 char *format_timestamp_us_utc(char *buf, size_t l, usec_t t) {
 366         return format_timestamp_internal(buf, l, t, true, true);
 367 }
 368 #endif // 0
 369
 370 char *format_timestamp_relative(char *buf, size_t l, usec_t t) {
 371         const char *s;
 372         usec_t n, d;
 373
 374         if (t <= 0 || t == USEC_INFINITY)
 375                 return NULL;
 376
 377         n = now(CLOCK_REALTIME);
 378         if (n > t) {
 379                 d = n - t;
 380                 s = "ago";
 381         } else {
 382                 d = t - n;
 383                 s = "left";
 384         }
 385
 386         if (d >= USEC_PER_YEAR)
 387                 snprintf(buf, l, USEC_FMT " years " USEC_FMT " months %s",
 388                          d / USEC_PER_YEAR,
 389                          (d % USEC_PER_YEAR) / USEC_PER_MONTH, s);
 390         else if (d >= USEC_PER_MONTH)
 391                 snprintf(buf, l, USEC_FMT " months " USEC_FMT " days %s",
 392                          d / USEC_PER_MONTH,
 393                          (d % USEC_PER_MONTH) / USEC_PER_DAY, s);
 394         else if (d >= USEC_PER_WEEK)
 395                 snprintf(buf, l, USEC_FMT " weeks " USEC_FMT " days %s",
 396                          d / USEC_PER_WEEK,
 397                          (d % USEC_PER_WEEK) / USEC_PER_DAY, s);
 398         else if (d >= 2*USEC_PER_DAY)
 399                 snprintf(buf, l, USEC_FMT " days %s", d / USEC_PER_DAY, s);
 400         else if (d >= 25*USEC_PER_HOUR)
 401                 snprintf(buf, l, "1 day " USEC_FMT "h %s",
 402                          (d - USEC_PER_DAY) / USEC_PER_HOUR, s);
 403         else if (d >= 6*USEC_PER_HOUR)
 404                 snprintf(buf, l, USEC_FMT "h %s",
 405                          d / USEC_PER_HOUR, s);
 406         else if (d >= USEC_PER_HOUR)
 407                 snprintf(buf, l, USEC_FMT "h " USEC_FMT "min %s",
 408                          d / USEC_PER_HOUR,
 409                          (d % USEC_PER_HOUR) / USEC_PER_MINUTE, s);
 410         else if (d >= 5*USEC_PER_MINUTE)
 411                 snprintf(buf, l, USEC_FMT "min %s",
 412                          d / USEC_PER_MINUTE, s);
 413         else if (d >= USEC_PER_MINUTE)
 414                 snprintf(buf, l, USEC_FMT "min " USEC_FMT "s %s",
 415                          d / USEC_PER_MINUTE,
 416                          (d % USEC_PER_MINUTE) / USEC_PER_SEC, s);
 417         else if (d >= USEC_PER_SEC)
 418                 snprintf(buf, l, USEC_FMT "s %s",
 419                          d / USEC_PER_SEC, s);
 420         else if (d >= USEC_PER_MSEC)
 421                 snprintf(buf, l, USEC_FMT "ms %s",
 422                          d / USEC_PER_MSEC, s);
 423         else if (d > 0)
 424                 snprintf(buf, l, USEC_FMT"us %s",
 425                          d, s);
 426         else
 427                 snprintf(buf, l, "now");
 428
 429         buf[l-1] = 0;
 430         return buf;
 431 }
 432
 433 char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy) {
 434         static const struct {
 435                 const char *suffix;
 436                 usec_t usec;
 437         } table[] = {
 438                 { "y",     USEC_PER_YEAR   },
 439                 { "month", USEC_PER_MONTH  },
 440                 { "w",     USEC_PER_WEEK   },
 441                 { "d",     USEC_PER_DAY    },
 442                 { "h",     USEC_PER_HOUR   },
 443                 { "min",   USEC_PER_MINUTE },
 444                 { "s",     USEC_PER_SEC    },
 445                 { "ms",    USEC_PER_MSEC   },
 446                 { "us",    1               },
 447         };
 448
 449         size_t i;
 450         char *p = buf;
 451         bool something = false;
 452
 453         assert(buf);
 454         assert(l > 0);
 455
 456         if (t == USEC_INFINITY) {
 457                 strncpy(p, "infinity", l-1);
 458                 p[l-1] = 0;
 459                 return p;
 460         }
 461
 462         if (t <= 0) {
 463                 strncpy(p, "0", l-1);
 464                 p[l-1] = 0;
 465                 return p;
 466         }
 467
 468         /* The result of this function can be parsed with parse_sec */
 469
 470         for (i = 0; i < ELEMENTSOF(table); i++) {
 471                 int k = 0;
 472                 size_t n;
 473                 bool done = false;
 474                 usec_t a, b;
 475
 476                 if (t <= 0)
 477                         break;
 478
 479                 if (t < accuracy && something)
 480                         break;
 481
 482                 if (t < table[i].usec)
 483                         continue;
 484
 485                 if (l <= 1)
 486                         break;
 487
 488                 a = t / table[i].usec;
 489                 b = t % table[i].usec;
 490
 491                 /* Let's see if we should shows this in dot notation */
 492                 if (t < USEC_PER_MINUTE && b > 0) {
 493                         usec_t cc;
 494                         int j;
 495
 496                         j = 0;
 497                         for (cc = table[i].usec; cc > 1; cc /= 10)
 498                                 j++;
 499
 500                         for (cc = accuracy; cc > 1; cc /= 10) {
 501                                 b /= 10;
 502                                 j--;
 503                         }
 504
 505                         if (j > 0) {
 506                                 k = snprintf(p, l,
 507                                              "%s"USEC_FMT".%0*"PRI_USEC"%s",
 508                                              p > buf ? " " : "",
 509                                              a,
 510                                              j,
 511                                              b,
 512                                              table[i].suffix);
 513
 514                                 t = 0;
 515                                 done = true;
 516                         }
 517                 }
 518
 519                 /* No? Then let's show it normally */
 520                 if (!done) {
 521                         k = snprintf(p, l,
 522                                      "%s"USEC_FMT"%s",
 523                                      p > buf ? " " : "",
 524                                      a,
 525                                      table[i].suffix);
 526
 527                         t = b;
 528                 }
 529
 530                 n = MIN((size_t) k, l);
 531
 532                 l -= n;
 533                 p += n;
 534
 535                 something = true;
 536         }
 537
 538         *p = 0;
 539
 540         return buf;
 541 }
 542
 543 #if 0 /// UNNEEDED by elogind
 544 void dual_timestamp_serialize(FILE *f, const char *name, dual_timestamp *t) {
 545
 546         assert(f);
 547         assert(name);
 548         assert(t);
 549
 550         if (!dual_timestamp_is_set(t))
 551                 return;
 552
 553         fprintf(f, "%s="USEC_FMT" "USEC_FMT"\n",
 554                 name,
 555                 t->realtime,
 556                 t->monotonic);
 557 }
 558
 559 int dual_timestamp_deserialize(const char *value, dual_timestamp *t) {
 560         uint64_t a, b;
 561         int r, pos;
 562
 563         assert(value);
 564         assert(t);
 565
 566         pos = strspn(value, WHITESPACE);
 567         if (value[pos] == '-')
 568                 return -EINVAL;
 569         pos += strspn(value + pos, DIGITS);
 570         pos += strspn(value + pos, WHITESPACE);
 571         if (value[pos] == '-')
 572                 return -EINVAL;
 573
 574         r = sscanf(value, "%" PRIu64 "%" PRIu64 "%n", &a, &b, &pos);
 575         if (r != 2) {
 576                 log_debug("Failed to parse dual timestamp value \"%s\".", value);
 577                 return -EINVAL;
 578         }
 579
 580         if (value[pos] != '\0')
 581                 /* trailing garbage */
 582                 return -EINVAL;
 583
 584         t->realtime = a;
 585         t->monotonic = b;
 586
 587         return 0;
 588 }
 589
 590 #endif // 0
 591 int timestamp_deserialize(const char *value, usec_t *timestamp) {
 592         int r;
 593
 594         assert(value);
 595
 596         r = safe_atou64(value, timestamp);
 597         if (r < 0)
 598                 return log_debug_errno(r, "Failed to parse timestamp value \"%s\": %m", value);
 599
 600         return r;
 601 }
 602
 603 #if 0 /// UNNEEDED by elogind
 604 static int parse_timestamp_impl(const char *t, usec_t *usec, bool with_tz) {
 605         static const struct {
 606                 const char *name;
 607                 const int nr;
 608         } day_nr[] = {
 609                 { "Sunday",    0 },
 610                 { "Sun",       0 },
 611                 { "Monday",    1 },
 612                 { "Mon",       1 },
 613                 { "Tuesday",   2 },
 614                 { "Tue",       2 },
 615                 { "Wednesday", 3 },
 616                 { "Wed",       3 },
 617                 { "Thursday",  4 },
 618                 { "Thu",       4 },
 619                 { "Friday",    5 },
 620                 { "Fri",       5 },
 621                 { "Saturday",  6 },
 622                 { "Sat",       6 },
 623         };
 624
 625         const char *k, *utc = NULL, *tzn = NULL;
 626         struct tm tm, copy;
 627         time_t x;
 628         usec_t x_usec, plus = 0, minus = 0, ret;
 629         int r, weekday = -1, dst = -1;
 630         size_t i;
 631
 632         /* Allowed syntaxes:
 633          *
 634          *   2012-09-22 16:34:22
 635          *   2012-09-22 16:34     (seconds will be set to 0)
 636          *   2012-09-22           (time will be set to 00:00:00)
 637          *   16:34:22             (date will be set to today)
 638          *   16:34                (date will be set to today, seconds to 0)
 639          *   now
 640          *   yesterday            (time is set to 00:00:00)
 641          *   today                (time is set to 00:00:00)
 642          *   tomorrow             (time is set to 00:00:00)
 643          *   +5min
 644          *   -5days
 645          *   @2147483647          (seconds since epoch)
 646          */
 647
 648         assert(t);
 649         assert(usec);
 650
 651         if (t[0] == '@' && !with_tz)
 652                 return parse_sec(t + 1, usec);
 653
 654         ret = now(CLOCK_REALTIME);
 655
 656         if (!with_tz) {
 657                 if (streq(t, "now"))
 658                         goto finish;
 659
 660                 else if (t[0] == '+') {
 661                         r = parse_sec(t+1, &plus);
 662                         if (r < 0)
 663                                 return r;
 664
 665                         goto finish;
 666
 667                 } else if (t[0] == '-') {
 668                         r = parse_sec(t+1, &minus);
 669                         if (r < 0)
 670                                 return r;
 671
 672                         goto finish;
 673
 674                 } else if ((k = endswith(t, " ago"))) {
 675                         t = strndupa(t, k - t);
 676
 677                         r = parse_sec(t, &minus);
 678                         if (r < 0)
 679                                 return r;
 680
 681                         goto finish;
 682
 683                 } else if ((k = endswith(t, " left"))) {
 684                         t = strndupa(t, k - t);
 685
 686                         r = parse_sec(t, &plus);
 687                         if (r < 0)
 688                                 return r;
 689
 690                         goto finish;
 691                 }
 692
 693                 /* See if the timestamp is suffixed with UTC */
 694                 utc = endswith_no_case(t, " UTC");
 695                 if (utc)
 696                         t = strndupa(t, utc - t);
 697                 else {
 698                         const char *e = NULL;
 699                         int j;
 700
 701                         tzset();
 702
 703                         /* See if the timestamp is suffixed by either the DST or non-DST local timezone. Note that we only
 704                          * support the local timezones here, nothing else. Not because we wouldn't want to, but simply because
 705                          * there are no nice APIs available to cover this. By accepting the local time zone strings, we make
 706                          * sure that all timestamps written by format_timestamp() can be parsed correctly, even though we don't
 707                          * support arbitrary timezone specifications. */
 708
 709                         for (j = 0; j <= 1; j++) {
 710
 711                                 if (isempty(tzname[j]))
 712                                         continue;
 713
 714                                 e = endswith_no_case(t, tzname[j]);
 715                                 if (!e)
 716                                         continue;
 717                                 if (e == t)
 718                                         continue;
 719                                 if (e[-1] != ' ')
 720                                         continue;
 721
 722                                 break;
 723                         }
 724
 725                         if (IN_SET(j, 0, 1)) {
 726                                 /* Found one of the two timezones specified. */
 727                                 t = strndupa(t, e - t - 1);
 728                                 dst = j;
 729                                 tzn = tzname[j];
 730                         }
 731                 }
 732         }
 733
 734         x = (time_t) (ret / USEC_PER_SEC);
 735         x_usec = 0;
 736
 737         if (!localtime_or_gmtime_r(&x, &tm, utc))
 738                 return -EINVAL;
 739
 740         tm.tm_isdst = dst;
 741         if (!with_tz && tzn)
 742                 tm.tm_zone = tzn;
 743
 744         if (streq(t, "today")) {
 745                 tm.tm_sec = tm.tm_min = tm.tm_hour = 0;
 746                 goto from_tm;
 747
 748         } else if (streq(t, "yesterday")) {
 749                 tm.tm_mday--;
 750                 tm.tm_sec = tm.tm_min = tm.tm_hour = 0;
 751                 goto from_tm;
 752
 753         } else if (streq(t, "tomorrow")) {
 754                 tm.tm_mday++;
 755                 tm.tm_sec = tm.tm_min = tm.tm_hour = 0;
 756                 goto from_tm;
 757         }
 758
 759         for (i = 0; i < ELEMENTSOF(day_nr); i++) {
 760                 size_t skip;
 761
 762                 if (!startswith_no_case(t, day_nr[i].name))
 763                         continue;
 764
 765                 skip = strlen(day_nr[i].name);
 766                 if (t[skip] != ' ')
 767                         continue;
 768
 769                 weekday = day_nr[i].nr;
 770                 t += skip + 1;
 771                 break;
 772         }
 773
 774         copy = tm;
 775         k = strptime(t, "%y-%m-%d %H:%M:%S", &tm);
 776         if (k) {
 777                 if (*k == '.')
 778                         goto parse_usec;
 779                 else if (*k == 0)
 780                         goto from_tm;
 781         }
 782
 783         tm = copy;
 784         k = strptime(t, "%Y-%m-%d %H:%M:%S", &tm);
 785         if (k) {
 786                 if (*k == '.')
 787                         goto parse_usec;
 788                 else if (*k == 0)
 789                         goto from_tm;
 790         }
 791
 792         tm = copy;
 793         k = strptime(t, "%y-%m-%d %H:%M", &tm);
 794         if (k && *k == 0) {
 795                 tm.tm_sec = 0;
 796                 goto from_tm;
 797         }
 798
 799         tm = copy;
 800         k = strptime(t, "%Y-%m-%d %H:%M", &tm);
 801         if (k && *k == 0) {
 802                 tm.tm_sec = 0;
 803                 goto from_tm;
 804         }
 805
 806         tm = copy;
 807         k = strptime(t, "%y-%m-%d", &tm);
 808         if (k && *k == 0) {
 809                 tm.tm_sec = tm.tm_min = tm.tm_hour = 0;
 810                 goto from_tm;
 811         }
 812
 813         tm = copy;
 814         k = strptime(t, "%Y-%m-%d", &tm);
 815         if (k && *k == 0) {
 816                 tm.tm_sec = tm.tm_min = tm.tm_hour = 0;
 817                 goto from_tm;
 818         }
 819
 820         tm = copy;
 821         k = strptime(t, "%H:%M:%S", &tm);
 822         if (k) {
 823                 if (*k == '.')
 824                         goto parse_usec;
 825                 else if (*k == 0)
 826                         goto from_tm;
 827         }
 828
 829         tm = copy;
 830         k = strptime(t, "%H:%M", &tm);
 831         if (k && *k == 0) {
 832                 tm.tm_sec = 0;
 833                 goto from_tm;
 834         }
 835
 836         return -EINVAL;
 837
 838 parse_usec:
 839         {
 840                 unsigned add;
 841
 842                 k++;
 843                 r = parse_fractional_part_u(&k, 6, &add);
 844                 if (r < 0)
 845                         return -EINVAL;
 846
 847                 if (*k)
 848                         return -EINVAL;
 849
 850                 x_usec = add;
 851         }
 852
 853 from_tm:
 854         if (weekday >= 0 && tm.tm_wday != weekday)
 855                 return -EINVAL;
 856
 857         x = mktime_or_timegm(&tm, utc);
 858         if (x < 0)
 859                 return -EINVAL;
 860
 861         ret = (usec_t) x * USEC_PER_SEC + x_usec;
 862         if (ret > USEC_TIMESTAMP_FORMATTABLE_MAX)
 863                 return -EINVAL;
 864
 865 finish:
 866         if (ret + plus < ret) /* overflow? */
 867                 return -EINVAL;
 868         ret += plus;
 869         if (ret > USEC_TIMESTAMP_FORMATTABLE_MAX)
 870                 return -EINVAL;
 871
 872         if (ret >= minus)
 873                 ret -= minus;
 874         else
 875                 return -EINVAL;
 876
 877         *usec = ret;
 878
 879         return 0;
 880 }
 881
 882 typedef struct ParseTimestampResult {
 883         usec_t usec;
 884         int return_value;
 885 } ParseTimestampResult;
 886
 887 int parse_timestamp(const char *t, usec_t *usec) {
 888         char *last_space, *tz = NULL;
 889         ParseTimestampResult *shared, tmp;
 890         int r;
 891
 892         last_space = strrchr(t, ' ');
 893         if (last_space != NULL && timezone_is_valid(last_space + 1, LOG_DEBUG))
 894                 tz = last_space + 1;
 895
 896         if (!tz || endswith_no_case(t, " UTC"))
 897                 return parse_timestamp_impl(t, usec, false);
 898
 899         shared = mmap(NULL, sizeof *shared, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
 900         if (shared == MAP_FAILED)
 901                 return negative_errno();
 902
 903         r = safe_fork("(sd-timestamp)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_DEATHSIG|FORK_WAIT, NULL);
 904         if (r < 0) {
 905                 (void) munmap(shared, sizeof *shared);
 906                 return r;
 907         }
 908         if (r == 0) {
 909                 bool with_tz = true;
 910
 911                 if (setenv("TZ", tz, 1) != 0) {
 912                         shared->return_value = negative_errno();
 913                         _exit(EXIT_FAILURE);
 914                 }
 915
 916                 tzset();
 917
 918                 /* If there is a timezone that matches the tzname fields, leave the parsing to the implementation.
 919                  * Otherwise just cut it off. */
 920                 with_tz = !STR_IN_SET(tz, tzname[0], tzname[1]);
 921
 922                 /* Cut off the timezone if we dont need it. */
 923                 if (with_tz)
 924                         t = strndupa(t, last_space - t);
 925
 926                 shared->return_value = parse_timestamp_impl(t, &shared->usec, with_tz);
 927
 928                 _exit(EXIT_SUCCESS);
 929         }
 930
 931         tmp = *shared;
 932         if (munmap(shared, sizeof *shared) != 0)
 933                 return negative_errno();
 934
 935         if (tmp.return_value == 0)
 936                 *usec = tmp.usec;
 937
 938         return tmp.return_value;
 939 }
 940 #endif // 0
 941
 942 static char* extract_multiplier(char *p, usec_t *multiplier) {
 943         static const struct {
 944                 const char *suffix;
 945                 usec_t usec;
 946         } table[] = {
 947                 { "seconds", USEC_PER_SEC    },
 948                 { "second",  USEC_PER_SEC    },
 949                 { "sec",     USEC_PER_SEC    },
 950                 { "s",       USEC_PER_SEC    },
 951                 { "minutes", USEC_PER_MINUTE },
 952                 { "minute",  USEC_PER_MINUTE },
 953                 { "min",     USEC_PER_MINUTE },
 954                 { "months",  USEC_PER_MONTH  },
 955                 { "month",   USEC_PER_MONTH  },
 956                 { "M",       USEC_PER_MONTH  },
 957                 { "msec",    USEC_PER_MSEC   },
 958                 { "ms",      USEC_PER_MSEC   },
 959                 { "m",       USEC_PER_MINUTE },
 960                 { "hours",   USEC_PER_HOUR   },
 961                 { "hour",    USEC_PER_HOUR   },
 962                 { "hr",      USEC_PER_HOUR   },
 963                 { "h",       USEC_PER_HOUR   },
 964                 { "days",    USEC_PER_DAY    },
 965                 { "day",     USEC_PER_DAY    },
 966                 { "d",       USEC_PER_DAY    },
 967                 { "weeks",   USEC_PER_WEEK   },
 968                 { "week",    USEC_PER_WEEK   },
 969                 { "w",       USEC_PER_WEEK   },
 970                 { "years",   USEC_PER_YEAR   },
 971                 { "year",    USEC_PER_YEAR   },
 972                 { "y",       USEC_PER_YEAR   },
 973                 { "usec",    1ULL            },
 974                 { "us",      1ULL            },
 975                 { "µs",      1ULL            },
 976         };
 977         size_t i;
 978
 979         for (i = 0; i < ELEMENTSOF(table); i++) {
 980                 char *e;
 981
 982                 e = startswith(p, table[i].suffix);
 983                 if (e) {
 984                         *multiplier = table[i].usec;
 985                         return e;
 986                 }
 987         }
 988
 989         return p;
 990 }
 991
 992 int parse_time(const char *t, usec_t *usec, usec_t default_unit) {
 993         const char *p, *s;
 994         usec_t r = 0;
 995         bool something = false;
 996
 997         assert(t);
 998         assert(usec);
 999         assert(default_unit > 0);
1000
1001         p = t;
1002
1003         p += strspn(p, WHITESPACE);
1004         s = startswith(p, "infinity");
1005         if (s) {
1006                 s += strspn(s, WHITESPACE);
1007                 if (*s != 0)
1008                         return -EINVAL;
1009
1010                 *usec = USEC_INFINITY;
1011                 return 0;
1012         }
1013
1014         for (;;) {
1015                 long long l, z = 0;
1016                 char *e;
1017                 unsigned n = 0;
1018                 usec_t multiplier = default_unit, k;
1019
1020                 p += strspn(p, WHITESPACE);
1021
1022                 if (*p == 0) {
1023                         if (!something)
1024                                 return -EINVAL;
1025
1026                         break;
1027                 }
1028
1029                 errno = 0;
1030                 l = strtoll(p, &e, 10);
1031                 if (errno > 0)
1032                         return -errno;
1033                 if (l < 0)
1034                         return -ERANGE;
1035
1036                 if (*e == '.') {
1037                         char *b = e + 1;
1038
1039                         errno = 0;
1040                         z = strtoll(b, &e, 10);
1041                         if (errno > 0)
1042                                 return -errno;
1043
1044                         if (z < 0)
1045                                 return -ERANGE;
1046
1047                         if (e == b)
1048                                 return -EINVAL;
1049
1050                         n = e - b;
1051
1052                 } else if (e == p)
1053                         return -EINVAL;
1054
1055                 e += strspn(e, WHITESPACE);
1056                 p = extract_multiplier(e, &multiplier);
1057
1058                 something = true;
1059
1060                 k = (usec_t) z * multiplier;
1061
1062                 for (; n > 0; n--)
1063                         k /= 10;
1064
1065                 r += (usec_t) l * multiplier + k;
1066         }
1067
1068         *usec = r;
1069
1070         return 0;
1071 }
1072
1073 int parse_sec(const char *t, usec_t *usec) {
1074         return parse_time(t, usec, USEC_PER_SEC);
1075 }
1076
1077 #if 0 /// UNNEEDED by elogind
1078 int parse_sec_fix_0(const char *t, usec_t *usec) {
1079         assert(t);
1080         assert(usec);
1081
1082         t += strspn(t, WHITESPACE);
1083
1084         if (streq(t, "0")) {
1085                 *usec = USEC_INFINITY;
1086                 return 0;
1087         }
1088
1089         return parse_sec(t, usec);
1090 }
1091
1092 int parse_nsec(const char *t, nsec_t *nsec) {
1093         static const struct {
1094                 const char *suffix;
1095                 nsec_t nsec;
1096         } table[] = {
1097                 { "seconds", NSEC_PER_SEC },
1098                 { "second", NSEC_PER_SEC },
1099                 { "sec", NSEC_PER_SEC },
1100                 { "s", NSEC_PER_SEC },
1101                 { "minutes", NSEC_PER_MINUTE },
1102                 { "minute", NSEC_PER_MINUTE },
1103                 { "min", NSEC_PER_MINUTE },
1104                 { "months", NSEC_PER_MONTH },
1105                 { "month", NSEC_PER_MONTH },
1106                 { "msec", NSEC_PER_MSEC },
1107                 { "ms", NSEC_PER_MSEC },
1108                 { "m", NSEC_PER_MINUTE },
1109                 { "hours", NSEC_PER_HOUR },
1110                 { "hour", NSEC_PER_HOUR },
1111                 { "hr", NSEC_PER_HOUR },
1112                 { "h", NSEC_PER_HOUR },
1113                 { "days", NSEC_PER_DAY },
1114                 { "day", NSEC_PER_DAY },
1115                 { "d", NSEC_PER_DAY },
1116                 { "weeks", NSEC_PER_WEEK },
1117                 { "week", NSEC_PER_WEEK },
1118                 { "w", NSEC_PER_WEEK },
1119                 { "years", NSEC_PER_YEAR },
1120                 { "year", NSEC_PER_YEAR },
1121                 { "y", NSEC_PER_YEAR },
1122                 { "usec", NSEC_PER_USEC },
1123                 { "us", NSEC_PER_USEC },
1124                 { "µs", NSEC_PER_USEC },
1125                 { "nsec", 1ULL },
1126                 { "ns", 1ULL },
1127                 { "", 1ULL }, /* default is nsec */
1128         };
1129
1130         const char *p, *s;
1131         nsec_t r = 0;
1132         bool something = false;
1133
1134         assert(t);
1135         assert(nsec);
1136
1137         p = t;
1138
1139         p += strspn(p, WHITESPACE);
1140         s = startswith(p, "infinity");
1141         if (s) {
1142                 s += strspn(s, WHITESPACE);
1143                 if (*s != 0)
1144                         return -EINVAL;
1145
1146                 *nsec = NSEC_INFINITY;
1147                 return 0;
1148         }
1149
1150         for (;;) {
1151                 long long l, z = 0;
1152                 size_t n = 0, i;
1153                 char *e;
1154
1155                 p += strspn(p, WHITESPACE);
1156
1157                 if (*p == 0) {
1158                         if (!something)
1159                                 return -EINVAL;
1160
1161                         break;
1162                 }
1163
1164                 errno = 0;
1165                 l = strtoll(p, &e, 10);
1166
1167                 if (errno > 0)
1168                         return -errno;
1169
1170                 if (l < 0)
1171                         return -ERANGE;
1172
1173                 if (*e == '.') {
1174                         char *b = e + 1;
1175
1176                         errno = 0;
1177                         z = strtoll(b, &e, 10);
1178                         if (errno > 0)
1179                                 return -errno;
1180
1181                         if (z < 0)
1182                                 return -ERANGE;
1183
1184                         if (e == b)
1185                                 return -EINVAL;
1186
1187                         n = e - b;
1188
1189                 } else if (e == p)
1190                         return -EINVAL;
1191
1192                 e += strspn(e, WHITESPACE);
1193
1194                 for (i = 0; i < ELEMENTSOF(table); i++)
1195                         if (startswith(e, table[i].suffix)) {
1196                                 nsec_t k = (nsec_t) z * table[i].nsec;
1197
1198                                 for (; n > 0; n--)
1199                                         k /= 10;
1200
1201                                 r += (nsec_t) l * table[i].nsec + k;
1202                                 p = e + strlen(table[i].suffix);
1203
1204                                 something = true;
1205                                 break;
1206                         }
1207
1208                 if (i >= ELEMENTSOF(table))
1209                         return -EINVAL;
1210
1211         }
1212
1213         *nsec = r;
1214
1215         return 0;
1216 }
1217
1218 bool ntp_synced(void) {
1219         struct timex txc = {};
1220
1221         if (adjtimex(&txc) < 0)
1222                 return false;
1223
1224         if (txc.status & STA_UNSYNC)
1225                 return false;
1226
1227         return true;
1228 }
1229
1230 int get_timezones(char ***ret) {
1231         _cleanup_fclose_ FILE *f = NULL;
1232         _cleanup_strv_free_ char **zones = NULL;
1233         size_t n_zones = 0, n_allocated = 0;
1234
1235         assert(ret);
1236
1237         zones = strv_new("UTC", NULL);
1238         if (!zones)
1239                 return -ENOMEM;
1240
1241         n_allocated = 2;
1242         n_zones = 1;
1243
1244         f = fopen("/usr/share/zoneinfo/zone.tab", "re");
1245         if (f) {
1246                 char l[LINE_MAX];
1247
1248                 FOREACH_LINE(l, f, return -errno) {
1249                         char *p, *w;
1250                         size_t k;
1251
1252                         p = strstrip(l);
1253
1254                         if (isempty(p) || *p == '#')
1255                                 continue;
1256
1257                         /* Skip over country code */
1258                         p += strcspn(p, WHITESPACE);
1259                         p += strspn(p, WHITESPACE);
1260
1261                         /* Skip over coordinates */
1262                         p += strcspn(p, WHITESPACE);
1263                         p += strspn(p, WHITESPACE);
1264
1265                         /* Found timezone name */
1266                         k = strcspn(p, WHITESPACE);
1267                         if (k <= 0)
1268                                 continue;
1269
1270                         w = strndup(p, k);
1271                         if (!w)
1272                                 return -ENOMEM;
1273
1274                         if (!GREEDY_REALLOC(zones, n_allocated, n_zones + 2)) {
1275                                 free(w);
1276                                 return -ENOMEM;
1277                         }
1278
1279                         zones[n_zones++] = w;
1280                         zones[n_zones] = NULL;
1281                 }
1282
1283                 strv_sort(zones);
1284
1285         } else if (errno != ENOENT)
1286                 return -errno;
1287
1288         *ret = TAKE_PTR(zones);
1289
1290         return 0;
1291 }
1292
1293 bool timezone_is_valid(const char *name, int log_level) {
1294         bool slash = false;
1295         const char *p, *t;
1296         _cleanup_close_ int fd = -1;
1297         char buf[4];
1298         int r;
1299
1300         if (isempty(name))
1301                 return false;
1302
1303         if (name[0] == '/')
1304                 return false;
1305
1306         for (p = name; *p; p++) {
1307                 if (!(*p >= '0' && *p <= '9') &&
1308                     !(*p >= 'a' && *p <= 'z') &&
1309                     !(*p >= 'A' && *p <= 'Z') &&
1310                     !IN_SET(*p, '-', '_', '+', '/'))
1311                         return false;
1312
1313                 if (*p == '/') {
1314
1315                         if (slash)
1316                                 return false;
1317
1318                         slash = true;
1319                 } else
1320                         slash = false;
1321         }
1322
1323         if (slash)
1324                 return false;
1325
1326         t = strjoina("/usr/share/zoneinfo/", name);
1327
1328         fd = open(t, O_RDONLY|O_CLOEXEC);
1329         if (fd < 0) {
1330                 log_full_errno(log_level, errno, "Failed to open timezone file '%s': %m", t);
1331                 return false;
1332         }
1333
1334         r = fd_verify_regular(fd);
1335         if (r < 0) {
1336                 log_full_errno(log_level, r, "Timezone file '%s' is not  a regular file: %m", t);
1337                 return false;
1338         }
1339
1340         r = loop_read_exact(fd, buf, 4, false);
1341         if (r < 0) {
1342                 log_full_errno(log_level, r, "Failed to read from timezone file '%s': %m", t);
1343                 return false;
1344         }
1345
1346         /* Magic from tzfile(5) */
1347         if (memcmp(buf, "TZif", 4) != 0) {
1348                 log_full(log_level, "Timezone file '%s' has wrong magic bytes", t);
1349                 return false;
1350         }
1351
1352         return true;
1353 }
1354
1355 #endif // 0
1356 bool clock_boottime_supported(void) {
1357         static int supported = -1;
1358
1359         /* Note that this checks whether CLOCK_BOOTTIME is available in general as well as available for timerfds()! */
1360
1361         if (supported < 0) {
1362                 int fd;
1363
1364                 fd = timerfd_create(CLOCK_BOOTTIME, TFD_NONBLOCK|TFD_CLOEXEC);
1365                 if (fd < 0)
1366                         supported = false;
1367                 else {
1368                         safe_close(fd);
1369                         supported = true;
1370                 }
1371         }
1372
1373         return supported;
1374 }
1375
1376 #if 0 /// UNNEEDED by elogind
1377 clockid_t clock_boottime_or_monotonic(void) {
1378         if (clock_boottime_supported())
1379                 return CLOCK_BOOTTIME;
1380         else
1381                 return CLOCK_MONOTONIC;
1382 }
1383 #endif // 0
1384
1385 #if 1 /// let's add a diagnostic push to silence -Wimplicit-fallthrough to elogind
1386 #  if defined(__GNUC__) && (__GNUC__ > 6)
1387 #    pragma GCC diagnostic push
1388 #    pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
1389 #  endif // __GNUC__
1390 #endif // 1
1391 bool clock_supported(clockid_t clock) {
1392         struct timespec ts;
1393
1394         switch (clock) {
1395
1396         case CLOCK_MONOTONIC:
1397         case CLOCK_REALTIME:
1398                 return true;
1399
1400         case CLOCK_BOOTTIME:
1401                 return clock_boottime_supported();
1402
1403         case CLOCK_BOOTTIME_ALARM:
1404                 if (!clock_boottime_supported())
1405                         return false;
1406
1407                 _fallthrough_;
1408         default:
1409                 /* For everything else, check properly */
1410                 return clock_gettime(clock, &ts) >= 0;
1411         }
1412 }
1413 #if 1 /// end diagnostic push in elogind
1414 #  ifdef __GNUC__
1415 #    pragma GCC diagnostic pop
1416 #  endif // __GNUC__
1417 #endif // 1
1418
1419 #if 0 /// UNNEEDED by elogind
1420 int get_timezone(char **tz) {
1421         _cleanup_free_ char *t = NULL;
1422         const char *e;
1423         char *z;
1424         int r;
1425
1426         r = readlink_malloc("/etc/localtime", &t);
1427         if (r < 0)
1428                 return r; /* returns EINVAL if not a symlink */
1429
1430         e = path_startswith(t, "/usr/share/zoneinfo/");
1431         if (!e)
1432                 e = path_startswith(t, "../usr/share/zoneinfo/");
1433         if (!e)
1434                 return -EINVAL;
1435
1436         if (!timezone_is_valid(e, LOG_DEBUG))
1437                 return -EINVAL;
1438
1439         z = strdup(e);
1440         if (!z)
1441                 return -ENOMEM;
1442
1443         *tz = z;
1444         return 0;
1445 }
1446
1447 time_t mktime_or_timegm(struct tm *tm, bool utc) {
1448         return utc ? timegm(tm) : mktime(tm);
1449 }
1450 #endif // 0
1451
1452 struct tm *localtime_or_gmtime_r(const time_t *t, struct tm *tm, bool utc) {
1453         return utc ? gmtime_r(t, tm) : localtime_r(t, tm);
1454 }
1455
1456 #if 0 /// UNNEEDED by elogind
1457 unsigned long usec_to_jiffies(usec_t u) {
1458         static thread_local unsigned long hz = 0;
1459         long r;
1460
1461         if (hz == 0) {
1462                 r = sysconf(_SC_CLK_TCK);
1463
1464                 assert(r > 0);
1465                 hz = r;
1466         }
1467
1468         return DIV_ROUND_UP(u , USEC_PER_SEC / hz);
1469 }
1470
1471 usec_t usec_shift_clock(usec_t x, clockid_t from, clockid_t to) {
1472         usec_t a, b;
1473
1474         if (x == USEC_INFINITY)
1475                 return USEC_INFINITY;
1476         if (map_clock_id(from) == map_clock_id(to))
1477                 return x;
1478
1479         a = now(from);
1480         b = now(to);
1481
1482         if (x > a)
1483                 /* x lies in the future */
1484                 return usec_add(b, usec_sub_unsigned(x, a));
1485         else
1486                 /* x lies in the past */
1487                 return usec_sub_unsigned(b, usec_sub_unsigned(a, x));
1488 }
1489 #endif // 0
1490
1491 bool in_utc_timezone(void) {
1492         tzset();
1493
1494         return timezone == 0 && daylight == 0;
1495 }