unofficial mirror of emacs-devel@gnu.org 
 help / color / mirror / code / Atom feed
blob cb953d1b4ceea56b915c3756a7ba7a0ac39ef763 56005 bytes (raw)
name: src/timefns.c 	 # note: path name is non-authoritative(*)

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
 
/* Timestamp functions for Emacs

Copyright (C) 1985-1987, 1989, 1993-2019 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

#include "systime.h"

#include "blockinput.h"
#include "bignum.h"
#include "coding.h"
#include "lisp.h"
#include "pdumper.h"

#include <strftime.h>

#include <errno.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

#ifdef HAVE_TIMEZONE_T
# include <sys/param.h>
# if defined __NetBSD_Version__ && __NetBSD_Version__ < 700000000
#  define HAVE_TZALLOC_BUG true
# endif
#endif
#ifndef HAVE_TZALLOC_BUG
# define HAVE_TZALLOC_BUG false
#endif

enum { TM_YEAR_BASE = 1900 };

#ifndef HAVE_TM_GMTOFF
# define HAVE_TM_GMTOFF false
#endif

#ifndef TIME_T_MIN
# define TIME_T_MIN TYPE_MINIMUM (time_t)
#endif
#ifndef TIME_T_MAX
# define TIME_T_MAX TYPE_MAXIMUM (time_t)
#endif

/* Compile with -DFASTER_TIMEFNS=0 to disable common optimizations and
   allow easier testing of some slow-path code.  */
#ifndef FASTER_TIMEFNS
# define FASTER_TIMEFNS 1
#endif

/* Whether to warn about Lisp timestamps (TICKS . HZ) that may be
   instances of obsolete-format timestamps (HI . LO) where HI is
   the high-order bits and LO the low-order 16 bits.  Currently this
   is true, but it should change to false in a future version of
   Emacs.  Compile with -DWARN_OBSOLETE_TIMESTAMPS=0 to see what the
   future will be like.  */
#ifndef WARN_OBSOLETE_TIMESTAMPS
enum { WARN_OBSOLETE_TIMESTAMPS = true };
#endif

/* Although current-time etc. generate list-format timestamps
   (HI LO US PS), the plan is to change these functions to generate
   frequency-based timestamps (TICKS . HZ) in a future release.
   To try this now, compile with -DCURRENT_TIME_LIST=0.  */
#ifndef CURRENT_TIME_LIST
enum { CURRENT_TIME_LIST = true };
#endif

#if FIXNUM_OVERFLOW_P (1000000000)
static Lisp_Object timespec_hz;
#else
# define timespec_hz make_fixnum (TIMESPEC_HZ)
#endif

#define TRILLION 1000000000000
#if FIXNUM_OVERFLOW_P (TRILLION)
static Lisp_Object trillion;
# define ztrillion (XBIGNUM (trillion)->value)
#else
# define trillion make_fixnum (TRILLION)
# if ULONG_MAX < TRILLION || !FASTER_TIMEFNS
mpz_t ztrillion;
# endif
#endif

/* Return a struct timeval that is roughly equivalent to T.
   Use the least timeval not less than T.
   Return an extremal value if the result would overflow.  */
struct timeval
make_timeval (struct timespec t)
{
  struct timeval tv;
  tv.tv_sec = t.tv_sec;
  tv.tv_usec = t.tv_nsec / 1000;

  if (t.tv_nsec % 1000 != 0)
    {
      if (tv.tv_usec < 999999)
	tv.tv_usec++;
      else if (tv.tv_sec < TIME_T_MAX)
	{
	  tv.tv_sec++;
	  tv.tv_usec = 0;
	}
    }

  return tv;
}

/* Yield A's UTC offset, or an unspecified value if unknown.  */
static long int
tm_gmtoff (struct tm *a)
{
#if HAVE_TM_GMTOFF
  return a->tm_gmtoff;
#else
  return 0;
#endif
}

/* Yield A - B, measured in seconds.
   This function is copied from the GNU C Library.  */
static int
tm_diff (struct tm *a, struct tm *b)
{
  /* Compute intervening leap days correctly even if year is negative.
     Take care to avoid int overflow in leap day calculations,
     but it's OK to assume that A and B are close to each other.  */
  int a4 = (a->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (a->tm_year & 3);
  int b4 = (b->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (b->tm_year & 3);
  int a100 = a4 / 25 - (a4 % 25 < 0);
  int b100 = b4 / 25 - (b4 % 25 < 0);
  int a400 = a100 >> 2;
  int b400 = b100 >> 2;
  int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
  int years = a->tm_year - b->tm_year;
  int days = (365 * years + intervening_leap_days
	      + (a->tm_yday - b->tm_yday));
  return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
		+ (a->tm_min - b->tm_min))
	  + (a->tm_sec - b->tm_sec));
}

enum { tzeqlen = sizeof "TZ=" - 1 };

/* Time zones equivalent to current local time and to UTC, respectively.  */
static timezone_t local_tz;
static timezone_t const utc_tz = 0;

static struct tm *
emacs_localtime_rz (timezone_t tz, time_t const *t, struct tm *tm)
{
  tm = localtime_rz (tz, t, tm);
  if (!tm && errno == ENOMEM)
    memory_full (SIZE_MAX);
  return tm;
}

static AVOID
invalid_time_zone_specification (Lisp_Object zone)
{
  xsignal2 (Qerror, build_string ("Invalid time zone specification"), zone);
}

/* Free a timezone, except do not free the time zone for local time.
   Freeing utc_tz is also a no-op.  */
static void
xtzfree (timezone_t tz)
{
  if (tz != local_tz)
    tzfree (tz);
}

/* Convert the Lisp time zone rule ZONE to a timezone_t object.
   The returned value either is 0, or is LOCAL_TZ, or is newly allocated.
   If SETTZ, set Emacs local time to the time zone rule; otherwise,
   the caller should eventually pass the returned value to xtzfree.  */
static timezone_t
tzlookup (Lisp_Object zone, bool settz)
{
  static char const tzbuf_format[] = "<%+.*"pI"d>%s%"pI"d:%02d:%02d";
  char const *trailing_tzbuf_format = tzbuf_format + sizeof "<%+.*"pI"d" - 1;
  char tzbuf[sizeof tzbuf_format + 2 * INT_STRLEN_BOUND (EMACS_INT)];
  char const *zone_string;
  timezone_t new_tz;

  if (NILP (zone))
    return local_tz;
  else if (EQ (zone, Qt) || EQ (zone, make_fixnum (0)))
    {
      zone_string = "UTC0";
      new_tz = utc_tz;
    }
  else
    {
      bool plain_integer = FIXNUMP (zone);

      if (EQ (zone, Qwall))
	zone_string = 0;
      else if (STRINGP (zone))
	zone_string = SSDATA (ENCODE_SYSTEM (zone));
      else if (plain_integer || (CONSP (zone) && FIXNUMP (XCAR (zone))
				 && CONSP (XCDR (zone))))
	{
	  Lisp_Object abbr UNINIT;
	  if (!plain_integer)
	    {
	      abbr = XCAR (XCDR (zone));
	      zone = XCAR (zone);
	    }

	  EMACS_INT abszone = eabs (XFIXNUM (zone)), hour = abszone / (60 * 60);
	  int hour_remainder = abszone % (60 * 60);
	  int min = hour_remainder / 60, sec = hour_remainder % 60;

	  if (plain_integer)
	    {
	      int prec = 2;
	      EMACS_INT numzone = hour;
	      if (hour_remainder != 0)
		{
		  prec += 2, numzone = 100 * numzone + min;
		  if (sec != 0)
		    prec += 2, numzone = 100 * numzone + sec;
		}
	      sprintf (tzbuf, tzbuf_format, prec,
		       XFIXNUM (zone) < 0 ? -numzone : numzone,
		       &"-"[XFIXNUM (zone) < 0], hour, min, sec);
	      zone_string = tzbuf;
	    }
	  else
	    {
	      AUTO_STRING (leading, "<");
	      AUTO_STRING_WITH_LEN (trailing, tzbuf,
				    sprintf (tzbuf, trailing_tzbuf_format,
					     &"-"[XFIXNUM (zone) < 0],
					     hour, min, sec));
	      zone_string = SSDATA (concat3 (leading, ENCODE_SYSTEM (abbr),
					     trailing));
	    }
	}
      else
	invalid_time_zone_specification (zone);

      new_tz = tzalloc (zone_string);

      if (HAVE_TZALLOC_BUG && !new_tz && errno != ENOMEM && plain_integer
	  && XFIXNUM (zone) % (60 * 60) == 0)
	{
	  /* tzalloc mishandles POSIX strings; fall back on tzdb if
	     possible (Bug#30738).  */
	  sprintf (tzbuf, "Etc/GMT%+"pI"d", - (XFIXNUM (zone) / (60 * 60)));
	  new_tz = tzalloc (zone_string);
	}

      if (!new_tz)
	{
	  if (errno == ENOMEM)
	    memory_full (SIZE_MAX);
	  invalid_time_zone_specification (zone);
	}
    }

  if (settz)
    {
      block_input ();
      emacs_setenv_TZ (zone_string);
      tzset ();
      timezone_t old_tz = local_tz;
      local_tz = new_tz;
      tzfree (old_tz);
      unblock_input ();
    }

  return new_tz;
}

void
init_timefns (void)
{
#ifdef HAVE_UNEXEC
  /* A valid but unlikely setting for the TZ environment variable.
     It is OK (though a bit slower) if the user chooses this value.  */
  static char dump_tz_string[] = "TZ=UtC0";

  /* When just dumping out, set the time zone to a known unlikely value
     and skip the rest of this function.  */
  if (will_dump_with_unexec_p ())
    {
      xputenv (dump_tz_string);
      tzset ();
      return;
    }
#endif

  char *tz = getenv ("TZ");

#ifdef HAVE_UNEXEC
  /* If the execution TZ happens to be the same as the dump TZ,
     change it to some other value and then change it back,
     to force the underlying implementation to reload the TZ info.
     This is needed on implementations that load TZ info from files,
     since the TZ file contents may differ between dump and execution.  */
  if (tz && strcmp (tz, &dump_tz_string[tzeqlen]) == 0)
    {
      ++*tz;
      tzset ();
      --*tz;
    }
#endif

  /* Set the time zone rule now, so that the call to putenv is done
     before multiple threads are active.  */
  tzlookup (tz ? build_string (tz) : Qwall, true);
}

/* Report that a time value is out of range for Emacs.  */
void
time_overflow (void)
{
  error ("Specified time is not representable");
}

static AVOID
time_error (int err)
{
  switch (err)
    {
    case ENOMEM: memory_full (SIZE_MAX);
    case EOVERFLOW: time_overflow ();
    default: error ("Invalid time specification");
    }
}

static AVOID
invalid_hz (Lisp_Object hz)
{
  xsignal2 (Qerror, build_string ("Invalid time frequency"), hz);
}

/* Return the upper part of the time T (everything but the bottom 16 bits).  */
static Lisp_Object
hi_time (time_t t)
{
  return INT_TO_INTEGER (t >> LO_TIME_BITS);
}

/* Return the bottom bits of the time T.  */
static Lisp_Object
lo_time (time_t t)
{
  return make_fixnum (t & ((1 << LO_TIME_BITS) - 1));
}

/* Convert T into an Emacs time *RESULT, truncating toward minus infinity.
   Return zero if successful, an error number otherwise.  */
static int
decode_float_time (double t, struct lisp_time *result)
{
  if (!isfinite (t))
    return isnan (t) ? EINVAL : EOVERFLOW;
  /* Actual hz unknown; guess TIMESPEC_HZ.  */
  mpz_set_d (mpz[1], t);
  mpz_set_si (mpz[0], floor ((t - trunc (t)) * TIMESPEC_HZ));
  mpz_addmul_ui (mpz[0], mpz[1], TIMESPEC_HZ);
  result->ticks = make_integer_mpz ();
  result->hz = timespec_hz;
  return 0;
}

/* Compute S + NS/TIMESPEC_HZ as a double.
   Calls to this function suffer from double-rounding;
   work around some of the problem by using long double.  */
static double
s_ns_to_double (long double s, long double ns)
{
  return s + ns / TIMESPEC_HZ;
}

/* Make a 4-element timestamp (HI LO US PS) from TICKS and HZ.
   Drop any excess precision.  */
static Lisp_Object
ticks_hz_list4 (Lisp_Object ticks, Lisp_Object hz)
{
  mpz_t *zticks = bignum_integer (&mpz[0], ticks);
#if FASTER_TIMEFNS && TRILLION <= ULONG_MAX
  mpz_mul_ui (mpz[0], *zticks, TRILLION);
#else
  mpz_mul (mpz[0], *zticks, ztrillion);
#endif
  mpz_fdiv_q (mpz[0], mpz[0], *bignum_integer (&mpz[1], hz));
#if FASTER_TIMEFNS && TRILLION <= ULONG_MAX
  unsigned long int fullps = mpz_fdiv_q_ui (mpz[0], mpz[0], TRILLION);
  int us = fullps / 1000000;
  int ps = fullps % 1000000;
#else
  mpz_fdiv_qr (mpz[0], mpz[1], mpz[0], ztrillion);
  int ps = mpz_fdiv_q_ui (mpz[1], mpz[1], 1000000);
  int us = mpz_get_ui (mpz[1]);
#endif
  unsigned long ulo = mpz_get_ui (mpz[0]);
  if (mpz_sgn (mpz[0]) < 0)
    ulo = -ulo;
  int lo = ulo & ((1 << LO_TIME_BITS) - 1);
  mpz_fdiv_q_2exp (mpz[0], mpz[0], LO_TIME_BITS);
  return list4 (make_integer_mpz (), make_fixnum (lo),
		make_fixnum (us), make_fixnum (ps));
}

/* Set ROP to T.  */
static void
mpz_set_time (mpz_t rop, time_t t)
{
  if (EXPR_SIGNED (t))
    mpz_set_intmax (rop, t);
  else
    mpz_set_uintmax (rop, t);
}

/* Store into mpz[0] a clock tick count for T, assuming a
   TIMESPEC_HZ-frequency clock.  Use mpz[1] as a temp.  */
static void
timespec_mpz (struct timespec t)
{
  mpz_set_ui (mpz[0], t.tv_nsec);
  mpz_set_time (mpz[1], t.tv_sec);
  mpz_addmul_ui (mpz[0], mpz[1], TIMESPEC_HZ);
}

/* Convert T to a Lisp integer counting TIMESPEC_HZ ticks.  */
static Lisp_Object
timespec_ticks (struct timespec t)
{
  intmax_t accum;
  if (FASTER_TIMEFNS
      && !INT_MULTIPLY_WRAPV (t.tv_sec, TIMESPEC_HZ, &accum)
      && !INT_ADD_WRAPV (t.tv_nsec, accum, &accum))
    return make_int (accum);
  timespec_mpz (t);
  return make_integer_mpz ();
}

/* Convert T to a Lisp integer counting HZ ticks, taking the floor.
   Assume T is valid, but check HZ.  */
static Lisp_Object
time_hz_ticks (time_t t, Lisp_Object hz)
{
  if (FIXNUMP (hz))
    {
      if (XFIXNUM (hz) <= 0)
	invalid_hz (hz);
      intmax_t ticks;
      if (FASTER_TIMEFNS && !INT_MULTIPLY_WRAPV (t, XFIXNUM (hz), &ticks))
	return make_int (ticks);
    }
  else if (! (BIGNUMP (hz) && 0 < mpz_sgn (XBIGNUM (hz)->value)))
    invalid_hz (hz);

  mpz_set_time (mpz[0], t);
  mpz_mul (mpz[0], mpz[0], *bignum_integer (&mpz[1], hz));
  return make_integer_mpz ();
}
static Lisp_Object
lisp_time_hz_ticks (struct lisp_time t, Lisp_Object hz)
{
  if (FASTER_TIMEFNS && EQ (t.hz, hz))
    return t.ticks;
  if (FIXNUMP (hz))
    {
      if (XFIXNUM (hz) <= 0)
	invalid_hz (hz);
      intmax_t ticks;
      if (FASTER_TIMEFNS && FIXNUMP (t.ticks) && FIXNUMP (t.hz)
	  && !INT_MULTIPLY_WRAPV (XFIXNUM (t.ticks), XFIXNUM (hz), &ticks))
	return make_int (ticks / XFIXNUM (t.hz)
			 - (ticks % XFIXNUM (t.hz) < 0));
    }
  else if (! (BIGNUMP (hz) && 0 < mpz_sgn (XBIGNUM (hz)->value)))
    invalid_hz (hz);

  mpz_mul (mpz[0],
	   *bignum_integer (&mpz[0], t.ticks),
	   *bignum_integer (&mpz[1], hz));
  mpz_fdiv_q (mpz[0], mpz[0], *bignum_integer (&mpz[1], t.hz));
  return make_integer_mpz ();
}

/* Convert T to a Lisp integer counting seconds, taking the floor.  */
static Lisp_Object
lisp_time_seconds (struct lisp_time t)
{
  if (!FASTER_TIMEFNS)
    return lisp_time_hz_ticks (t, make_fixnum (1));
  if (FIXNUMP (t.ticks) && FIXNUMP (t.hz))
    return make_fixnum (XFIXNUM (t.ticks) / XFIXNUM (t.hz)
			- (XFIXNUM (t.ticks) % XFIXNUM (t.hz) < 0));
  mpz_fdiv_q (mpz[0],
	      *bignum_integer (&mpz[0], t.ticks),
	      *bignum_integer (&mpz[1], t.hz));
  return make_integer_mpz ();
}

/* Convert T to a Lisp timestamp.  */
Lisp_Object
make_lisp_time (struct timespec t)
{
  if (CURRENT_TIME_LIST)
    {
      time_t s = t.tv_sec;
      int ns = t.tv_nsec;
      return list4 (hi_time (s), lo_time (s),
		    make_fixnum (ns / 1000), make_fixnum (ns % 1000 * 1000));
    }
  else
    return Fcons (timespec_ticks (t), timespec_hz);
}

/* Convert T to a Lisp timestamp.  FORM specifies the timestamp format.  */
static Lisp_Object
time_form_stamp (time_t t, Lisp_Object form)
{
  if (NILP (form))
    form = CURRENT_TIME_LIST ? Qlist : Qt;
  if (EQ (form, Qlist))
    return list2 (hi_time (t), lo_time (t));
  if (EQ (form, Qt) || EQ (form, Qinteger))
    return INT_TO_INTEGER (t);
  return Fcons (time_hz_ticks (t, form), form);
}
static Lisp_Object
lisp_time_form_stamp (struct lisp_time t, Lisp_Object form)
{
  if (NILP (form))
    form = CURRENT_TIME_LIST ? Qlist : Qt;
  if (EQ (form, Qlist))
    return ticks_hz_list4 (t.ticks, t.hz);
  if (EQ (form, Qinteger))
    return lisp_time_seconds (t);
  if (EQ (form, Qt))
    form = t.hz;
  return Fcons (lisp_time_hz_ticks (t, form), form);
}

/* From what should be a valid timestamp (TICKS . HZ), generate the
   corresponding time values.

   If RESULT is not null, store into *RESULT the converted time.
   Otherwise, store into *DRESULT the number of seconds since the
   start of the POSIX Epoch.  Unsuccessful calls may or may not store
   results.

   Return zero if successful, an error number if (TICKS . HZ) would not
   be a valid new-format timestamp.  */
static int
decode_ticks_hz (Lisp_Object ticks, Lisp_Object hz,
		 struct lisp_time *result, double *dresult)
{
  int ns;
  mpz_t *q = &mpz[0];

  if (! (INTEGERP (ticks)
	 && ((FIXNUMP (hz) && 0 < XFIXNUM (hz))
	     || (BIGNUMP (hz) && 0 < mpz_sgn (XBIGNUM (hz)->value)))))
    return EINVAL;

  if (result)
    {
      result->ticks = ticks;
      result->hz = hz;
    }
  else
    {
      if (FASTER_TIMEFNS && EQ (hz, timespec_hz))
	{
	  if (FIXNUMP (ticks))
	    {
	      verify (1 < TIMESPEC_HZ);
	      EMACS_INT s = XFIXNUM (ticks) / TIMESPEC_HZ;
	      ns = XFIXNUM (ticks) % TIMESPEC_HZ;
	      if (ns < 0)
		s--, ns += TIMESPEC_HZ;
	      *dresult = s_ns_to_double (s, ns);
	      return 0;
	    }
	  ns = mpz_fdiv_q_ui (*q, XBIGNUM (ticks)->value, TIMESPEC_HZ);
	}
      else if (FASTER_TIMEFNS && EQ (hz, make_fixnum (1)))
	{
	  ns = 0;
	  if (FIXNUMP (ticks))
	    {
	      *dresult = XFIXNUM (ticks);
	      return 0;
	    }
	  q = &XBIGNUM (ticks)->value;
	}
      else
	{
	  mpz_mul_ui (*q, *bignum_integer (&mpz[1], ticks), TIMESPEC_HZ);
	  mpz_fdiv_q (*q, *q, *bignum_integer (&mpz[1], hz));
	  ns = mpz_fdiv_q_ui (*q, *q, TIMESPEC_HZ);
	}

      *dresult = s_ns_to_double (mpz_get_d (*q), ns);
    }

  return 0;
}

/* Lisp timestamp classification.  */
enum timeform
  {
   TIMEFORM_INVALID = 0,
   TIMEFORM_HI_LO, /* seconds in the form (HI << LO_TIME_BITS) + LO.  */
   TIMEFORM_HI_LO_US, /* seconds plus microseconds (HI LO US) */
   TIMEFORM_NIL, /* current time in nanoseconds */
   TIMEFORM_HI_LO_US_PS, /* seconds plus micro and picoseconds (HI LO US PS) */
   TIMEFORM_FLOAT, /* time as a float */
   TIMEFORM_TICKS_HZ /* fractional time: HI is ticks, LO is ticks per second */
  };

/* From the valid form FORM and the time components HIGH, LOW, USEC
   and PSEC, generate the corresponding time value.  If LOW is
   floating point, the other components should be zero and FORM should
   not be TIMEFORM_TICKS_HZ.

   If RESULT is not null, store into *RESULT the converted time.
   Otherwise, store into *DRESULT the number of seconds since the
   start of the POSIX Epoch.  Unsuccessful calls may or may not store
   results.

   Return zero if successful, an error number otherwise.  */
static int
decode_time_components (enum timeform form,
			Lisp_Object high, Lisp_Object low,
			Lisp_Object usec, Lisp_Object psec,
			struct lisp_time *result, double *dresult)
{
  switch (form)
    {
    case TIMEFORM_INVALID:
      return EINVAL;

    case TIMEFORM_TICKS_HZ:
      return decode_ticks_hz (high, low, result, dresult);

    case TIMEFORM_FLOAT:
      {
	double t = XFLOAT_DATA (low);
	if (result)
	  return decode_float_time (t, result);
	else
	  {
	    *dresult = t;
	    return 0;
	  }
      }

    case TIMEFORM_NIL:
      {
	struct timespec now = current_timespec ();
	if (result)
	  {
	    result->ticks = timespec_ticks (now);
	    result->hz = timespec_hz;
	  }
	else
	  *dresult = s_ns_to_double (now.tv_sec, now.tv_nsec);
	return 0;
      }

    default:
      break;
    }

  if (! (INTEGERP (high) && INTEGERP (low)
	 && FIXNUMP (usec) && FIXNUMP (psec)))
    return EINVAL;
  EMACS_INT us = XFIXNUM (usec);
  EMACS_INT ps = XFIXNUM (psec);

  /* Normalize out-of-range lower-order components by carrying
     each overflow into the next higher-order component.  */
  us += ps / 1000000 - (ps % 1000000 < 0);
  mpz_set_intmax (mpz[0], us / 1000000 - (us % 1000000 < 0));
  mpz_add (mpz[0], mpz[0], *bignum_integer (&mpz[1], low));
  mpz_addmul_ui (mpz[0], *bignum_integer (&mpz[1], high), 1 << LO_TIME_BITS);
  ps = ps % 1000000 + 1000000 * (ps % 1000000 < 0);
  us = us % 1000000 + 1000000 * (us % 1000000 < 0);

  if (result)
    {
      switch (form)
	{
	case TIMEFORM_HI_LO:
	  /* Floats and nil were handled above, so it was an integer.  */
	  result->hz = make_fixnum (1);
	  break;

	case TIMEFORM_HI_LO_US:
	  mpz_mul_ui (mpz[0], mpz[0], 1000000);
	  mpz_add_ui (mpz[0], mpz[0], us);
	  result->hz = make_fixnum (1000000);
	  break;

	case TIMEFORM_HI_LO_US_PS:
	  mpz_mul_ui (mpz[0], mpz[0], 1000000);
	  mpz_add_ui (mpz[0], mpz[0], us);
	  mpz_mul_ui (mpz[0], mpz[0], 1000000);
	  mpz_add_ui (mpz[0], mpz[0], ps);
	  result->hz = trillion;
	  break;

	default:
	  eassume (false);
	}
      result->ticks = make_integer_mpz ();
    }
  else
    *dresult = mpz_get_d (mpz[0]) + (us * 1e6L + ps) / 1e12L;

  return 0;
}

enum { DECODE_SECS_ONLY = WARN_OBSOLETE_TIMESTAMPS + 1 };

/* Decode a Lisp timestamp SPECIFIED_TIME that represents a time.

   FLAGS specifies conversion flags.  If FLAGS & DECODE_SECS_ONLY,
   ignore and do not validate any sub-second components of an
   old-format SPECIFIED_TIME.  If FLAGS & WARN_OBSOLETE_TIMESTAMPS,
   diagnose what could be obsolete (HIGH . LOW) timestamps.

   If PFORM is not null, store into *PFORM the form of SPECIFIED-TIME.
   If RESULT is not null, store into *RESULT the converted time;
   otherwise, store into *DRESULT the number of seconds since the
   start of the POSIX Epoch.  Unsuccessful calls may or may not store
   results.

   Signal an error if unsuccessful.  */
static void
decode_lisp_time (Lisp_Object specified_time, int flags,
		  enum timeform *pform,
		  struct lisp_time *result, double *dresult)
{
  Lisp_Object high = make_fixnum (0);
  Lisp_Object low = specified_time;
  Lisp_Object usec = make_fixnum (0);
  Lisp_Object psec = make_fixnum (0);
  enum timeform form = TIMEFORM_HI_LO;

  if (NILP (specified_time))
    form = TIMEFORM_NIL;
  else if (FLOATP (specified_time))
    form = TIMEFORM_FLOAT;
  else if (CONSP (specified_time))
    {
      high = XCAR (specified_time);
      low = XCDR (specified_time);
      if (CONSP (low))
	{
	  Lisp_Object low_tail = XCDR (low);
	  low = XCAR (low);
	  if (! (flags & DECODE_SECS_ONLY))
	    {
	      if (CONSP (low_tail))
		{
		  usec = XCAR (low_tail);
		  low_tail = XCDR (low_tail);
		  if (CONSP (low_tail))
		    {
		      psec = XCAR (low_tail);
		      form = TIMEFORM_HI_LO_US_PS;
		    }
		  else
		    form = TIMEFORM_HI_LO_US;
		}
	      else if (!NILP (low_tail))
		{
		  usec = low_tail;
		  form = TIMEFORM_HI_LO_US;
		}
	    }
	}
      else
	{
	  if (flags & WARN_OBSOLETE_TIMESTAMPS
	      && RANGED_FIXNUMP (0, low, (1 << LO_TIME_BITS) - 1))
	    message ("obsolete timestamp with cdr %"pI"d", XFIXNUM (low));
	  form = TIMEFORM_TICKS_HZ;
	}

      /* Require LOW to be an integer, as otherwise the computation
	 would be considerably trickier.  */
      if (! INTEGERP (low))
	form = TIMEFORM_INVALID;
    }

  if (pform)
    *pform = form;
  int err = decode_time_components (form, high, low, usec, psec,
				    result, dresult);
  if (err)
    time_error (err);
}

/* Convert Z to time_t, returning true if it fits.  */
static bool
mpz_time (mpz_t const z, time_t *t)
{
  if (TYPE_SIGNED (time_t))
    {
      intmax_t i;
      if (! (mpz_to_intmax (z, &i) && TIME_T_MIN <= i && i <= TIME_T_MAX))
	return false;
      *t = i;
    }
  else
    {
      uintmax_t i;
      if (! (mpz_to_uintmax (z, &i) && i <= TIME_T_MAX))
	return false;
      *t = i;
    }
  return true;
}

/* Convert T to struct timespec, returning an invalid timespec
   if T does not fit.  */
static struct timespec
lisp_to_timespec (struct lisp_time t)
{
  struct timespec result = invalid_timespec ();
  int ns;
  mpz_t *q = &mpz[0];

  if (FASTER_TIMEFNS && EQ (t.hz, timespec_hz))
    {
      if (FIXNUMP (t.ticks))
	{
	  EMACS_INT s = XFIXNUM (t.ticks) / TIMESPEC_HZ;
	  ns = XFIXNUM (t.ticks) % TIMESPEC_HZ;
	  if (ns < 0)
	    s--, ns += TIMESPEC_HZ;
	  if ((TYPE_SIGNED (time_t) ? TIME_T_MIN <= s : 0 <= s)
	      && s <= TIME_T_MAX)
	    {
	      result.tv_sec = s;
	      result.tv_nsec = ns;
	    }
	  return result;
	}
      else
	ns = mpz_fdiv_q_ui (*q, XBIGNUM (t.ticks)->value, TIMESPEC_HZ);
    }
  else if (FASTER_TIMEFNS && EQ (t.hz, make_fixnum (1)))
    {
      ns = 0;
      if (FIXNUMP (t.ticks))
	{
	  EMACS_INT s = XFIXNUM (t.ticks);
	  if ((TYPE_SIGNED (time_t) ? TIME_T_MIN <= s : 0 <= s)
	      && s <= TIME_T_MAX)
	    {
	      result.tv_sec = s;
	      result.tv_nsec = ns;
	    }
	  return result;
	}
      else
	q = &XBIGNUM (t.ticks)->value;
    }
  else
    {
      mpz_mul_ui (*q, *bignum_integer (q, t.ticks), TIMESPEC_HZ);
      mpz_fdiv_q (*q, *q, *bignum_integer (&mpz[1], t.hz));
      ns = mpz_fdiv_q_ui (*q, *q, TIMESPEC_HZ);
    }

  /* With some versions of MinGW, tv_sec is a 64-bit type, whereas
     time_t is a 32-bit type.  */
  time_t sec;
  if (mpz_time (*q, &sec))
    {
      result.tv_sec = sec;
      result.tv_nsec = ns;
    }
  return result;
}

/* Convert (HIGH LOW USEC PSEC) to struct timespec.
   Return true if successful.  */
bool
list4_to_timespec (Lisp_Object high, Lisp_Object low,
		   Lisp_Object usec, Lisp_Object psec,
		   struct timespec *result)
{
  struct lisp_time t;
  if (decode_time_components (TIMEFORM_HI_LO_US_PS, high, low, usec, psec,
			      &t, 0))
    return false;
  *result = lisp_to_timespec (t);
  return timespec_valid_p (*result);
}

/* Decode a Lisp list SPECIFIED_TIME that represents a time.
   If SPECIFIED_TIME is nil, use the current time.
   Signal an error if SPECIFIED_TIME does not represent a time.  */
static struct lisp_time
lisp_time_struct (Lisp_Object specified_time, enum timeform *pform)
{
  struct lisp_time t;
  decode_lisp_time (specified_time, WARN_OBSOLETE_TIMESTAMPS, pform, &t, 0);
  return t;
}

/* Decode a Lisp list SPECIFIED_TIME that represents a time.
   Discard any low-order (sub-ns) resolution.
   If SPECIFIED_TIME is nil, use the current time.
   Signal an error if SPECIFIED_TIME does not represent a timespec.  */
struct timespec
lisp_time_argument (Lisp_Object specified_time)
{
  struct lisp_time lt = lisp_time_struct (specified_time, 0);
  struct timespec t = lisp_to_timespec (lt);
  if (! timespec_valid_p (t))
    time_overflow ();
  return t;
}

/* Like lisp_time_argument, except decode only the seconds part, and
   do not check the subseconds part.  */
static time_t
lisp_seconds_argument (Lisp_Object specified_time)
{
  int flags = WARN_OBSOLETE_TIMESTAMPS | DECODE_SECS_ONLY;
  struct lisp_time lt;
  decode_lisp_time (specified_time, flags, 0, &lt, 0);
  struct timespec t = lisp_to_timespec (lt);
  if (! timespec_valid_p (t))
    time_overflow ();
  return t.tv_sec;
}

/* Given Lisp operands A and B, add their values, and return the
   result as a Lisp timestamp that is in (TICKS . HZ) form if either A
   or B are in that form, (HI LO US PS) form otherwise.  Subtract
   instead of adding if SUBTRACT.  */
static Lisp_Object
time_arith (Lisp_Object a, Lisp_Object b, bool subtract)
{
  if (FLOATP (a) && !isfinite (XFLOAT_DATA (a)))
    {
      double da = XFLOAT_DATA (a);
      double db = XFLOAT_DATA (Ffloat_time (b));
      return make_float (subtract ? da - db : da + db);
    }
  if (FLOATP (b) && !isfinite (XFLOAT_DATA (b)))
    return subtract ? make_float (-XFLOAT_DATA (b)) : b;

  enum timeform aform, bform;
  struct lisp_time ta = lisp_time_struct (a, &aform);
  struct lisp_time tb = lisp_time_struct (b, &bform);
  Lisp_Object ticks, hz;

  if (FASTER_TIMEFNS && EQ (ta.hz, tb.hz))
    {
      hz = ta.hz;
      if (FIXNUMP (ta.ticks) && FIXNUMP (tb.ticks))
	ticks = make_int (subtract
			  ? XFIXNUM (ta.ticks) - XFIXNUM (tb.ticks)
			  : XFIXNUM (ta.ticks) + XFIXNUM (tb.ticks));
      else
	{
	  (subtract ? mpz_sub : mpz_add)
	    (mpz[0],
	     *bignum_integer (&mpz[0], ta.ticks),
	     *bignum_integer (&mpz[1], tb.ticks));
	  ticks = make_integer_mpz ();
	}
    }
  else
    {
      /* The plan is to decompose ta into na/da and tb into nb/db.
	 Start by computing da and db.  */
      mpz_t *da = bignum_integer (&mpz[1], ta.hz);
      mpz_t *db = bignum_integer (&mpz[2], tb.hz);

      /* The plan is to compute (na * (db/g) + nb * (da/g)) / lcm (da, db)
	 where g = gcd (da, db).  Start by computing g.  */
      mpz_t *g = &mpz[3];
      mpz_gcd (*g, *da, *db);

      /* fa = da/g, fb = db/g.  */
      mpz_t *fa = &mpz[1], *fb = &mpz[3];
      mpz_tdiv_q (*fa, *da, *g);
      mpz_tdiv_q (*fb, *db, *g);

      /* FIXME: Maybe omit need for extra temp by computing fa * db here?  */

      /* hz = fa * db.  This is equal to lcm (da, db).  */
      mpz_mul (mpz[0], *fa, *db);
      hz = make_integer_mpz ();

      /* ticks = (fb * na) OPER (fa * nb), where OPER is + or -.
	 OP is the multiply-add or multiply-sub form of OPER.  */
      mpz_t *na = bignum_integer (&mpz[0], ta.ticks);
      mpz_mul (mpz[0], *fb, *na);
      mpz_t *nb = bignum_integer (&mpz[3], tb.ticks);
      (subtract ? mpz_submul : mpz_addmul) (mpz[0], *fa, *nb);
      ticks = make_integer_mpz ();
    }

  /* Return the (TICKS . HZ) form if either argument is that way,
     otherwise the (HI LO US PS) form for backward compatibility.  */
  return (aform == TIMEFORM_TICKS_HZ || bform == TIMEFORM_TICKS_HZ
	  ? Fcons (ticks, hz)
	  : ticks_hz_list4 (ticks, hz));
}

DEFUN ("time-add", Ftime_add, Stime_add, 2, 2, 0,
       doc: /* Return the sum of two time values A and B, as a time value.
See `format-time-string' for the various forms of a time value.
For example, nil stands for the current time.  */)
  (Lisp_Object a, Lisp_Object b)
{
  return time_arith (a, b, false);
}

DEFUN ("time-subtract", Ftime_subtract, Stime_subtract, 2, 2, 0,
       doc: /* Return the difference between two time values A and B, as a time value.
You can use `float-time' to convert the difference into elapsed seconds.
See `format-time-string' for the various forms of a time value.
For example, nil stands for the current time.  */)
  (Lisp_Object a, Lisp_Object b)
{
  return time_arith (a, b, true);
}

/* Return negative, 0, positive if a < b, a == b, a > b respectively.
   Return positive if either a or b is a NaN; this is good enough
   for the current callers.  */
static int
time_cmp (Lisp_Object a, Lisp_Object b)
{
  if ((FLOATP (a) && !isfinite (XFLOAT_DATA (a)))
      || (FLOATP (b) && !isfinite (XFLOAT_DATA (b))))
    {
      double da = FLOATP (a) ? XFLOAT_DATA (a) : 0;
      double db = FLOATP (b) ? XFLOAT_DATA (b) : 0;
      return da < db ? -1 : da != db;
    }

  struct lisp_time ta = lisp_time_struct (a, 0);

  /* Compare nil to nil correctly, and other eq values while we're at it.
     Compare here rather than earlier, to handle NaNs and check formats.  */
  if (EQ (a, b))
    return 0;

  struct lisp_time tb = lisp_time_struct (b, 0);
  mpz_t *za = bignum_integer (&mpz[0], ta.ticks);
  mpz_t *zb = bignum_integer (&mpz[1], tb.ticks);
  if (! (FASTER_TIMEFNS && EQ (ta.hz, tb.hz)))
    {
      /* This could be sped up by looking at the signs, sizes, and
	 number of bits of the two sides; see how GMP does mpq_cmp.
	 It may not be worth the trouble here, though.  */
      mpz_mul (mpz[0], *za, *bignum_integer (&mpz[2], tb.hz));
      mpz_mul (mpz[1], *zb, *bignum_integer (&mpz[2], ta.hz));
      za = &mpz[0];
      zb = &mpz[1];
    }
  return mpz_cmp (*za, *zb);
}

DEFUN ("time-less-p", Ftime_less_p, Stime_less_p, 2, 2, 0,
       doc: /* Return non-nil if time value A is less than time value B.
See `format-time-string' for the various forms of a time value.
For example, nil stands for the current time.  */)
  (Lisp_Object a, Lisp_Object b)
{
  return time_cmp (a, b) < 0 ? Qt : Qnil;
}

DEFUN ("time-equal-p", Ftime_equal_p, Stime_equal_p, 2, 2, 0,
       doc: /* Return non-nil if A and B are equal time values.
See `format-time-string' for the various forms of a time value.  */)
  (Lisp_Object a, Lisp_Object b)
{
  return time_cmp (a, b) == 0 ? Qt : Qnil;
}
\f

DEFUN ("float-time", Ffloat_time, Sfloat_time, 0, 1, 0,
       doc: /* Return the current time, as a float number of seconds since the epoch.
If SPECIFIED-TIME is given, it is a time value to convert to float
instead of the current time.  See `format-time-string' for the various
forms of a time value.

WARNING: Since the result is floating point, it may not be exact.
If precise time stamps are required, use either `encode-time',
or (if you need time as a string) `format-time-string'.  */)
  (Lisp_Object specified_time)
{
  double t;
  decode_lisp_time (specified_time, 0, 0, 0, &t);
  return make_float (t);
}

/* Write information into buffer S of size MAXSIZE, according to the
   FORMAT of length FORMAT_LEN, using time information taken from *TP.
   Use the time zone specified by TZ.
   Use NS as the number of nanoseconds in the %N directive.
   Return the number of bytes written, not including the terminating
   '\0'.  If S is NULL, nothing will be written anywhere; so to
   determine how many bytes would be written, use NULL for S and
   ((size_t) -1) for MAXSIZE.

   This function behaves like nstrftime, except it allows NUL
   bytes in FORMAT and it does not support nanoseconds.  */
static size_t
emacs_nmemftime (char *s, size_t maxsize, const char *format,
		 size_t format_len, const struct tm *tp, timezone_t tz, int ns)
{
  size_t total = 0;

  /* Loop through all the NUL-terminated strings in the format
     argument.  Normally there's just one NUL-terminated string, but
     there can be arbitrarily many, concatenated together, if the
     format contains '\0' bytes.  nstrftime stops at the first
     '\0' byte so we must invoke it separately for each such string.  */
  for (;;)
    {
      size_t len;
      size_t result;

      if (s)
	s[0] = '\1';

      result = nstrftime (s, maxsize, format, tp, tz, ns);

      if (s)
	{
	  if (result == 0 && s[0] != '\0')
	    return 0;
	  s += result + 1;
	}

      maxsize -= result + 1;
      total += result;
      len = strlen (format);
      if (len == format_len)
	return total;
      total++;
      format += len + 1;
      format_len -= len + 1;
    }
}

static Lisp_Object
format_time_string (char const *format, ptrdiff_t formatlen,
		    struct timespec t, Lisp_Object zone, struct tm *tmp)
{
  char buffer[4000];
  char *buf = buffer;
  ptrdiff_t size = sizeof buffer;
  size_t len;
  int ns = t.tv_nsec;
  USE_SAFE_ALLOCA;

  timezone_t tz = tzlookup (zone, false);
  /* On some systems, like 32-bit MinGW, tv_sec of struct timespec is
     a 64-bit type, but time_t is a 32-bit type.  emacs_localtime_rz
     expects a pointer to time_t value.  */
  time_t tsec = t.tv_sec;
  tmp = emacs_localtime_rz (tz, &tsec, tmp);
  if (! tmp)
    {
      int localtime_errno = errno;
      xtzfree (tz);
      time_error (localtime_errno);
    }
  synchronize_system_time_locale ();

  while (true)
    {
      buf[0] = '\1';
      len = emacs_nmemftime (buf, size, format, formatlen, tmp, tz, ns);
      if ((0 < len && len < size) || (len == 0 && buf[0] == '\0'))
	break;

      /* Buffer was too small, so make it bigger and try again.  */
      len = emacs_nmemftime (NULL, SIZE_MAX, format, formatlen, tmp, tz, ns);
      if (STRING_BYTES_BOUND <= len)
	{
	  xtzfree (tz);
	  string_overflow ();
	}
      size = len + 1;
      buf = SAFE_ALLOCA (size);
    }

  xtzfree (tz);
  AUTO_STRING_WITH_LEN (bufstring, buf, len);
  Lisp_Object result = code_convert_string_norecord (bufstring,
						     Vlocale_coding_system, 0);
  SAFE_FREE ();
  return result;
}

DEFUN ("format-time-string", Fformat_time_string, Sformat_time_string, 1, 3, 0,
       doc: /* Use FORMAT-STRING to format the time value TIME.
A time value that is omitted or nil stands for the current time,
a number stands for that many seconds, an integer pair (TICKS . HZ)
stands for TICKS/HZ seconds, and an integer list (HI LO US PS) stands
for HI*2**16 + LO + US/10**6 + PS/10**12 seconds.  This function
treats seconds as time since the epoch of 1970-01-01 00:00:00 UTC.

The optional ZONE is omitted or nil for Emacs local time, t for
Universal Time, `wall' for system wall clock time, or a string as in
the TZ environment variable.  It can also be a list (as from
`current-time-zone') or an integer (as from `decode-time') applied
without consideration for daylight saving time.

The value is a copy of FORMAT-STRING, but with certain constructs replaced
by text that describes the specified date and time in TIME:

%Y is the year, %y within the century, %C the century.
%G is the year corresponding to the ISO week, %g within the century.
%m is the numeric month.
%b and %h are the locale's abbreviated month name, %B the full name.
 (%h is not supported on MS-Windows.)
%d is the day of the month, zero-padded, %e is blank-padded.
%u is the numeric day of week from 1 (Monday) to 7, %w from 0 (Sunday) to 6.
%a is the locale's abbreviated name of the day of week, %A the full name.
%U is the week number starting on Sunday, %W starting on Monday,
 %V according to ISO 8601.
%j is the day of the year.

%H is the hour on a 24-hour clock, %I is on a 12-hour clock, %k is like %H
 only blank-padded, %l is like %I blank-padded.
%p is the locale's equivalent of either AM or PM.
%q is the calendar quarter (1–4).
%M is the minute (00-59).
%S is the second (00-59; 00-60 on platforms with leap seconds)
%s is the number of seconds since 1970-01-01 00:00:00 +0000.
%N is the nanosecond, %6N the microsecond, %3N the millisecond, etc.
%Z is the time zone abbreviation, %z is the numeric form.

%c is the locale's date and time format.
%x is the locale's "preferred" date format.
%D is like "%m/%d/%y".
%F is the ISO 8601 date format (like "%+4Y-%m-%d").

%R is like "%H:%M", %T is like "%H:%M:%S", %r is like "%I:%M:%S %p".
%X is the locale's "preferred" time format.

Finally, %n is a newline, %t is a tab, %% is a literal %, and
unrecognized %-sequences stand for themselves.

A %-sequence can contain optional flags, field width, and a modifier
(in that order) after the `%'.  The flags are:

`-' Do not pad the field.
`_' Pad with spaces.
`0' Pad with zeros.
`+' Pad with zeros and put `+' before nonnegative year numbers with >4 digits.
`^' Use upper case characters if possible.
`#' Use opposite case characters if possible.

A field width N is an unsigned decimal integer with a leading digit nonzero.
%NX is like %X, but takes up at least N positions.

The modifiers are:

`E' Use the locale's alternative version.
`O' Use the locale's number symbols.

For example, to produce full ISO 8601 format, use "%FT%T%z".

usage: (format-time-string FORMAT-STRING &optional TIME ZONE)  */)
  (Lisp_Object format_string, Lisp_Object timeval, Lisp_Object zone)
{
  struct timespec t = lisp_time_argument (timeval);
  struct tm tm;

  CHECK_STRING (format_string);
  format_string = code_convert_string_norecord (format_string,
						Vlocale_coding_system, 1);
  return format_time_string (SSDATA (format_string), SBYTES (format_string),
			     t, zone, &tm);
}

DEFUN ("decode-time", Fdecode_time, Sdecode_time, 0, 2, 0,
       doc: /* Decode a time value as (SEC MINUTE HOUR DAY MONTH YEAR DOW DST UTCOFF).
The optional TIME is the time value to convert.  See
`format-time-string' for the various forms of a time value.

The optional ZONE is omitted or nil for Emacs local time, t for
Universal Time, `wall' for system wall clock time, or a string as in
the TZ environment variable.  It can also be a list (as from
`current-time-zone') or an integer (the UTC offset in seconds) applied
without consideration for daylight saving time.

The list has the following nine members: SEC is an integer between 0
and 60; SEC is 60 for a leap second, which only some operating systems
support.  MINUTE is an integer between 0 and 59.  HOUR is an integer
between 0 and 23.  DAY is an integer between 1 and 31.  MONTH is an
integer between 1 and 12.  YEAR is an integer indicating the
four-digit year.  DOW is the day of week, an integer between 0 and 6,
where 0 is Sunday.  DST is t if daylight saving time is in effect,
nil if it is not in effect, and -1 if daylight saving information is
not available.  UTCOFF is an integer indicating the UTC offset in
seconds, i.e., the number of seconds east of Greenwich.  (Note that
Common Lisp has different meanings for DOW and UTCOFF.)

usage: (decode-time &optional TIME ZONE)  */)
  (Lisp_Object specified_time, Lisp_Object zone)
{
  time_t time_spec = lisp_seconds_argument (specified_time);
  struct tm local_tm, gmt_tm;
  timezone_t tz = tzlookup (zone, false);
  struct tm *tm = emacs_localtime_rz (tz, &time_spec, &local_tm);
  int localtime_errno = errno;
  xtzfree (tz);

  if (!tm)
    time_error (localtime_errno);

  Lisp_Object year;
  if (FASTER_TIMEFNS
      && MOST_NEGATIVE_FIXNUM - TM_YEAR_BASE <= local_tm.tm_year
      && local_tm.tm_year <= MOST_POSITIVE_FIXNUM - TM_YEAR_BASE)
    {
      /* Avoid overflow when INT_MAX - TM_YEAR_BASE < local_tm.tm_year.  */
      EMACS_INT tm_year_base = TM_YEAR_BASE;
      year = make_fixnum (local_tm.tm_year + tm_year_base);
    }
  else
    {
      mpz_set_si (mpz[0], local_tm.tm_year);
      mpz_add_ui (mpz[0], mpz[0], TM_YEAR_BASE);
      year = make_integer_mpz ();
    }

  return CALLN (Flist,
		make_fixnum (local_tm.tm_sec),
		make_fixnum (local_tm.tm_min),
		make_fixnum (local_tm.tm_hour),
		make_fixnum (local_tm.tm_mday),
		make_fixnum (local_tm.tm_mon + 1),
		year,
		make_fixnum (local_tm.tm_wday),
		(local_tm.tm_isdst < 0 ? make_fixnum (-1)
		 : local_tm.tm_isdst == 0 ? Qnil : Qt),
		(HAVE_TM_GMTOFF
		 ? make_fixnum (tm_gmtoff (&local_tm))
		 : gmtime_r (&time_spec, &gmt_tm)
		 ? make_fixnum (tm_diff (&local_tm, &gmt_tm))
		 : Qnil));
}

/* Return OBJ - OFFSET, checking that OBJ is a valid integer and that
   the result is representable as an int.  0 <= OFFSET <= TM_YEAR_BASE.  */
static int
check_tm_member (Lisp_Object obj, int offset)
{
  if (FASTER_TIMEFNS && INT_MAX <= MOST_POSITIVE_FIXNUM - TM_YEAR_BASE)
    {
      CHECK_FIXNUM (obj);
      EMACS_INT n = XFIXNUM (obj);
      int i;
      if (INT_SUBTRACT_WRAPV (n, offset, &i))
	time_overflow ();
      return i;
    }
  else
    {
      CHECK_INTEGER (obj);
      mpz_sub_ui (mpz[0], *bignum_integer (&mpz[0], obj), offset);
      intmax_t i;
      if (! (mpz_to_intmax (mpz[0], &i) && INT_MIN <= i && i <= INT_MAX))
	time_overflow ();
      return i;
    }
}

DEFUN ("encode-time", Fencode_time, Sencode_time, 1, MANY, 0,
       doc: /* Convert optional TIME to a timestamp.
Optional FORM specifies how the returned value should be encoded.
This can act as the reverse operation of `decode-time', which see.

If TIME is a list (SECOND MINUTE HOUR DAY MONTH YEAR IGNORED DST ZONE)
it is a decoded time in the style of `decode-time', so that (encode-time
(decode-time ...)) works.  TIME can also be a time value.
See `format-time-string' for the various forms of a time value.
For example, an omitted TIME stands for the current time.

If FORM is a positive integer, the time is returned as a pair of
integers (TICKS . FORM), where TICKS is the number of clock ticks and FORM
is the clock frequency in ticks per second.  (Currently the positive
integer should be at least 65536 if the returned value is expected to
be given to standard functions expecting Lisp timestamps.)  If FORM is
t, the time is returned as (TICKS . PHZ), where PHZ is a platform dependent
clock frequency in ticks per second.  If FORM is `integer', the time is
returned as an integer count of seconds.  If FORM is `list', the time is
returned as an integer list (HIGH LOW USEC PSEC), where HIGH has the
most significant bits of the seconds, LOW has the least significant 16
bits, and USEC and PSEC are the microsecond and picosecond counts.
Returned values are rounded toward minus infinity.  Although an
omitted or nil FORM currently acts like `list', this is planned to
change, so callers requiring list timestamps should specify `list'.

As an obsolescent calling convention, if this function is called with
6 or more arguments, the first 6 arguments are SECOND, MINUTE, HOUR,
DAY, MONTH, and YEAR, and specify the components of a decoded time,
where DST assumed to be -1 and FORM is omitted.  If there are more
than 6 arguments the *last* argument is used as ZONE and any other
extra arguments are ignored, so that (apply #\\='encode-time
(decode-time ...)) works; otherwise ZONE is assumed to be nil.

If the input is a decoded time, ZONE is nil for Emacs local time, t
for Universal Time, `wall' for system wall clock time, or a string as
in the TZ environment variable.  It can also be a list (as from
`current-time-zone') or an integer (as from `decode-time') applied
without consideration for daylight saving time.

If the input is a decoded time and ZONE specifies a time zone with
daylight-saving transitions, DST is t for daylight saving time and nil
for standard time.  If DST is -1, the daylight saving flag is guessed.

Out-of-range values for SECOND, MINUTE, HOUR, DAY, or MONTH are allowed;
for example, a DAY of 0 means the day preceding the given month.
Year numbers less than 100 are treated just like other year numbers.
If you want them to stand for years in this century, you must do that yourself.

Years before 1970 are not guaranteed to work.  On some systems,
year values as low as 1901 do work.

usage: (encode-time &optional TIME FORM &rest OBSOLESCENT-ARGUMENTS)  */)
  (ptrdiff_t nargs, Lisp_Object *args)
{
  struct tm tm;
  Lisp_Object form = Qnil, zone = Qnil;
  Lisp_Object a = args[0];
  tm.tm_isdst = -1;

  if (nargs <= 2)
    {
      if (nargs == 2)
	form = args[1];
      Lisp_Object tail = a;
      for (int i = 0; i < 9; i++, tail = XCDR (tail))
	if (! CONSP (tail))
	  {
	    struct lisp_time t;
	    decode_lisp_time (a, 0, 0, &t, 0);
	    return lisp_time_form_stamp (t, form);
	  }
      tm.tm_sec  = check_tm_member (XCAR (a), 0); a = XCDR (a);
      tm.tm_min  = check_tm_member (XCAR (a), 0); a = XCDR (a);
      tm.tm_hour = check_tm_member (XCAR (a), 0); a = XCDR (a);
      tm.tm_mday = check_tm_member (XCAR (a), 0); a = XCDR (a);
      tm.tm_mon  = check_tm_member (XCAR (a), 1); a = XCDR (a);
      tm.tm_year = check_tm_member (XCAR (a), TM_YEAR_BASE); a = XCDR (a);
      a = XCDR (a);
      if (SYMBOLP (XCAR (a)))
	tm.tm_isdst = !NILP (XCAR (a));
      a = XCDR (a);
      zone = XCAR (a);
    }
  else if (nargs < 6)
    xsignal2 (Qwrong_number_of_arguments, Qencode_time, make_fixnum (nargs));
  else
    {
      if (6 < nargs)
	zone = args[nargs - 1];
      tm.tm_sec  = check_tm_member (a, 0);
      tm.tm_min  = check_tm_member (args[1], 0);
      tm.tm_hour = check_tm_member (args[2], 0);
      tm.tm_mday = check_tm_member (args[3], 0);
      tm.tm_mon  = check_tm_member (args[4], 1);
      tm.tm_year = check_tm_member (args[5], TM_YEAR_BASE);
    }

  timezone_t tz = tzlookup (zone, false);
  tm.tm_wday = -1;
  time_t value = mktime_z (tz, &tm);
  int mktime_errno = errno;
  xtzfree (tz);

  if (tm.tm_wday < 0)
    time_error (mktime_errno);

  return time_form_stamp (value, form);
}

DEFUN ("current-time", Fcurrent_time, Scurrent_time, 0, 0, 0,
       doc: /* Return the current time, as the number of seconds since 1970-01-01 00:00:00.
The time is returned as a list of integers (HIGH LOW USEC PSEC).
HIGH has the most significant bits of the seconds, while LOW has the
least significant 16 bits.  USEC and PSEC are the microsecond and
picosecond counts.  Use `encode-time' if you need a particular
timestamp form; for example, (encode-time nil \\='integer) returns the
current time in seconds.  */)
  (void)
{
  return make_lisp_time (current_timespec ());
}

DEFUN ("current-time-string", Fcurrent_time_string, Scurrent_time_string,
       0, 2, 0,
       doc: /* Return the current local time, as a human-readable string.
Programs can use this function to decode a time,
since the number of columns in each field is fixed
if the year is in the range 1000-9999.
The format is `Sun Sep 16 01:03:52 1973'.
However, see also the functions `decode-time' and `format-time-string'
which provide a much more powerful and general facility.

If SPECIFIED-TIME is given, it is the time value to format instead of
the current time.  See `format-time-string' for the various forms of a
time value.

The optional ZONE is omitted or nil for Emacs local time, t for
Universal Time, `wall' for system wall clock time, or a string as in
the TZ environment variable.  It can also be a list (as from
`current-time-zone') or an integer (as from `decode-time') applied
without consideration for daylight saving time.  */)
  (Lisp_Object specified_time, Lisp_Object zone)
{
  time_t value = lisp_seconds_argument (specified_time);
  timezone_t tz = tzlookup (zone, false);

  /* Convert to a string in ctime format, except without the trailing
     newline, and without the 4-digit year limit.  Don't use asctime
     or ctime, as they might dump core if the year is outside the
     range -999 .. 9999.  */
  struct tm tm;
  struct tm *tmp = emacs_localtime_rz (tz, &value, &tm);
  int localtime_errno = errno;
  xtzfree (tz);
  if (! tmp)
    time_error (localtime_errno);

  static char const wday_name[][4] =
    { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
  static char const mon_name[][4] =
    { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
      "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
  printmax_t year_base = TM_YEAR_BASE;
  char buf[sizeof "Mon Apr 30 12:49:17 " + INT_STRLEN_BOUND (int) + 1];
  int len = sprintf (buf, "%s %s%3d %02d:%02d:%02d %"pMd,
		     wday_name[tm.tm_wday], mon_name[tm.tm_mon], tm.tm_mday,
		     tm.tm_hour, tm.tm_min, tm.tm_sec,
		     tm.tm_year + year_base);

  return make_unibyte_string (buf, len);
}

DEFUN ("current-time-zone", Fcurrent_time_zone, Scurrent_time_zone, 0, 2, 0,
       doc: /* Return the offset and name for the local time zone.
This returns a list of the form (OFFSET NAME).
OFFSET is an integer number of seconds ahead of UTC (east of Greenwich).
    A negative value means west of Greenwich.
NAME is a string giving the name of the time zone.
If SPECIFIED-TIME is given, the time zone offset is determined from it
instead of using the current time.  The argument should be a Lisp
time value; see `format-time-string' for the various forms of a time
value.

The optional ZONE is omitted or nil for Emacs local time, t for
Universal Time, `wall' for system wall clock time, or a string as in
the TZ environment variable.  It can also be a list (as from
`current-time-zone') or an integer (as from `decode-time') applied
without consideration for daylight saving time.

Some operating systems cannot provide all this information to Emacs;
in this case, `current-time-zone' returns a list containing nil for
the data it can't find.  */)
  (Lisp_Object specified_time, Lisp_Object zone)
{
  struct timespec value;
  struct tm local_tm, gmt_tm;
  Lisp_Object zone_offset, zone_name;

  zone_offset = Qnil;
  value = make_timespec (lisp_seconds_argument (specified_time), 0);
  zone_name = format_time_string ("%Z", sizeof "%Z" - 1, value,
				  zone, &local_tm);

  /* gmtime_r expects a pointer to time_t, but tv_sec of struct
     timespec on some systems (MinGW) is a 64-bit field.  */
  time_t tsec = value.tv_sec;
  if (HAVE_TM_GMTOFF || gmtime_r (&tsec, &gmt_tm))
    {
      long int offset = (HAVE_TM_GMTOFF
			 ? tm_gmtoff (&local_tm)
			 : tm_diff (&local_tm, &gmt_tm));
      zone_offset = make_fixnum (offset);
      if (SCHARS (zone_name) == 0)
	{
	  /* No local time zone name is available; use numeric zone instead.  */
	  long int hour = offset / 3600;
	  int min_sec = offset % 3600;
	  int amin_sec = min_sec < 0 ? - min_sec : min_sec;
	  int min = amin_sec / 60;
	  int sec = amin_sec % 60;
	  int min_prec = min_sec ? 2 : 0;
	  int sec_prec = sec ? 2 : 0;
	  char buf[sizeof "+0000" + INT_STRLEN_BOUND (long int)];
	  zone_name = make_formatted_string (buf, "%c%.2ld%.*d%.*d",
					     (offset < 0 ? '-' : '+'),
					     hour, min_prec, min, sec_prec, sec);
	}
    }

  return list2 (zone_offset, zone_name);
}

DEFUN ("set-time-zone-rule", Fset_time_zone_rule, Sset_time_zone_rule, 1, 1, 0,
       doc: /* Set the Emacs local time zone using TZ, a string specifying a time zone rule.
If TZ is nil or `wall', use system wall clock time; this differs from
the usual Emacs convention where nil means current local time.  If TZ
is t, use Universal Time.  If TZ is a list (as from
`current-time-zone') or an integer (as from `decode-time'), use the
specified time zone without consideration for daylight saving time.

Instead of calling this function, you typically want something else.
To temporarily use a different time zone rule for just one invocation
of `decode-time', `encode-time', or `format-time-string', pass the
function a ZONE argument.  To change local time consistently
throughout Emacs, call (setenv "TZ" TZ): this changes both the
environment of the Emacs process and the variable
`process-environment', whereas `set-time-zone-rule' affects only the
former.  */)
  (Lisp_Object tz)
{
  tzlookup (NILP (tz) ? Qwall : tz, true);
  return Qnil;
}

/* A buffer holding a string of the form "TZ=value", intended
   to be part of the environment.  If TZ is supposed to be unset,
   the buffer string is "tZ=".  */
 static char *tzvalbuf;

/* Get the local time zone rule.  */
char *
emacs_getenv_TZ (void)
{
  return tzvalbuf[0] == 'T' ? tzvalbuf + tzeqlen : 0;
}

/* Set the local time zone rule to TZSTRING, which can be null to
   denote wall clock time.  Do not record the setting in LOCAL_TZ.

   This function is not thread-safe, in theory because putenv is not,
   but mostly because of the static storage it updates.  Other threads
   that invoke localtime etc. may be adversely affected while this
   function is executing.  */

int
emacs_setenv_TZ (const char *tzstring)
{
  static ptrdiff_t tzvalbufsize;
  ptrdiff_t tzstringlen = tzstring ? strlen (tzstring) : 0;
  char *tzval = tzvalbuf;
  bool new_tzvalbuf = tzvalbufsize <= tzeqlen + tzstringlen;

  if (new_tzvalbuf)
    {
      /* Do not attempt to free the old tzvalbuf, since another thread
	 may be using it.  In practice, the first allocation is large
	 enough and memory does not leak.  */
      tzval = xpalloc (NULL, &tzvalbufsize,
		       tzeqlen + tzstringlen - tzvalbufsize + 1, -1, 1);
      tzvalbuf = tzval;
      tzval[1] = 'Z';
      tzval[2] = '=';
    }

  if (tzstring)
    {
      /* Modify TZVAL in place.  Although this is dicey in a
	 multithreaded environment, we know of no portable alternative.
	 Calling putenv or setenv could crash some other thread.  */
      tzval[0] = 'T';
      strcpy (tzval + tzeqlen, tzstring);
    }
  else
    {
      /* Turn 'TZ=whatever' into an empty environment variable 'tZ='.
	 Although this is also dicey, calling unsetenv here can crash Emacs.
	 See Bug#8705.  */
      tzval[0] = 't';
      tzval[tzeqlen] = 0;
    }


#ifndef WINDOWSNT
  /* Modifying *TZVAL merely requires calling tzset (which is the
     caller's responsibility).  However, modifying TZVAL requires
     calling putenv; although this is not thread-safe, in practice this
     runs only on startup when there is only one thread.  */
  bool need_putenv = new_tzvalbuf;
#else
  /* MS-Windows 'putenv' copies the argument string into a block it
     allocates, so modifying *TZVAL will not change the environment.
     However, the other threads run by Emacs on MS-Windows never call
     'xputenv' or 'putenv' or 'unsetenv', so the original cause for the
     dicey in-place modification technique doesn't exist there in the
     first place.  */
  bool need_putenv = true;
#endif
  if (need_putenv)
    xputenv (tzval);

  return 0;
}

#if (ULONG_MAX < TRILLION || !FASTER_TIMEFNS) && !defined ztrillion
# define NEED_ZTRILLION_INIT 1
#endif

#ifdef NEED_ZTRILLION_INIT
static void
syms_of_timefns_for_pdumper (void)
{
  mpz_init_set_ui (ztrillion, 1000000);
  mpz_mul_ui (ztrillion, ztrillion, 1000000);
}
#endif

void
syms_of_timefns (void)
{
#ifndef timespec_hz
  timespec_hz = make_int (TIMESPEC_HZ);
  staticpro (&timespec_hz);
#endif
#ifndef trillion
  trillion = make_int (1000000000000);
  staticpro (&trillion);
#endif

  DEFSYM (Qencode_time, "encode-time");

  defsubr (&Scurrent_time);
  defsubr (&Stime_add);
  defsubr (&Stime_subtract);
  defsubr (&Stime_less_p);
  defsubr (&Stime_equal_p);
  defsubr (&Sformat_time_string);
  defsubr (&Sfloat_time);
  defsubr (&Sdecode_time);
  defsubr (&Sencode_time);
  defsubr (&Scurrent_time_string);
  defsubr (&Scurrent_time_zone);
  defsubr (&Sset_time_zone_rule);
#ifdef NEED_ZTRILLION_INIT
  pdumper_do_now_and_after_load (syms_of_timefns_for_pdumper);
#endif
}

debug log:

solving cb953d1b4c ...
found cb953d1b4c in https://git.savannah.gnu.org/cgit/emacs.git

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/emacs.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).