timezone/private.h

   1 #ifndef PRIVATE_H
   2
   3 #define PRIVATE_H
   4
   5 /*
   6 ** This file is in the public domain, so clarified as of
   7 ** 1996-06-05 by Arthur David Olson.
   8 */
   9
  10 /*
  11 ** This header is for use ONLY with the time conversion code.
  12 ** There is no guarantee that it will remain unchanged,
  13 ** or that it will remain at all.
  14 ** Do NOT copy it to any system include directory.
  15 ** Thank you!
  16 */
  17
  18 /* This string was in the Factory zone through version 2016f.  */
  19 #define GRANDPARENTED   "Local time zone must be set--see zic manual page"
  20
  21 /*
  22 ** Defaults for preprocessor symbols.
  23 ** You can override these in your C compiler options, e.g. '-DHAVE_GETTEXT=1'.
  24 */
  25
  26 #ifndef HAVE_DECL_ASCTIME_R
  27 #define HAVE_DECL_ASCTIME_R 1
  28 #endif
  29
  30 #ifndef HAVE_GETTEXT
  31 #define HAVE_GETTEXT            0
  32 #endif /* !defined HAVE_GETTEXT */
  33
  34 #ifndef HAVE_INCOMPATIBLE_CTIME_R
  35 #define HAVE_INCOMPATIBLE_CTIME_R       0
  36 #endif /* !defined INCOMPATIBLE_CTIME_R */
  37
  38 #ifndef HAVE_LINK
  39 #define HAVE_LINK               1
  40 #endif /* !defined HAVE_LINK */
  41
  42 #ifndef HAVE_POSIX_DECLS
  43 #define HAVE_POSIX_DECLS 1
  44 #endif
  45
  46 #ifndef HAVE_STRDUP
  47 #define HAVE_STRDUP 1
  48 #endif
  49
  50 #ifndef HAVE_SYMLINK
  51 #define HAVE_SYMLINK            1
  52 #endif /* !defined HAVE_SYMLINK */
  53
  54 #ifndef HAVE_SYS_STAT_H
  55 #define HAVE_SYS_STAT_H         1
  56 #endif /* !defined HAVE_SYS_STAT_H */
  57
  58 #ifndef HAVE_SYS_WAIT_H
  59 #define HAVE_SYS_WAIT_H         1
  60 #endif /* !defined HAVE_SYS_WAIT_H */
  61
  62 #ifndef HAVE_UNISTD_H
  63 #define HAVE_UNISTD_H           1
  64 #endif /* !defined HAVE_UNISTD_H */
  65
  66 #ifndef HAVE_UTMPX_H
  67 #define HAVE_UTMPX_H            1
  68 #endif /* !defined HAVE_UTMPX_H */
  69
  70 #ifndef NETBSD_INSPIRED
  71 # define NETBSD_INSPIRED 1
  72 #endif
  73
  74 #if HAVE_INCOMPATIBLE_CTIME_R
  75 #define asctime_r _incompatible_asctime_r
  76 #define ctime_r _incompatible_ctime_r
  77 #endif /* HAVE_INCOMPATIBLE_CTIME_R */
  78
  79 /* Enable tm_gmtoff and tm_zone on GNUish systems.  */
  80 #define _GNU_SOURCE 1
  81 /* Fix asctime_r on Solaris 11.  */
  82 #define _POSIX_PTHREAD_SEMANTICS 1
  83 /* Enable strtoimax on pre-C99 Solaris 11.  */
  84 #define __EXTENSIONS__ 1
  85
  86 /*
  87 ** Nested includes
  88 */
  89
  90 /* Avoid clashes with NetBSD by renaming NetBSD's declarations.  */
  91 #define localtime_rz sys_localtime_rz
  92 #define mktime_z sys_mktime_z
  93 #define posix2time_z sys_posix2time_z
  94 #define time2posix_z sys_time2posix_z
  95 #define timezone_t sys_timezone_t
  96 #define tzalloc sys_tzalloc
  97 #define tzfree sys_tzfree
  98 #include <time.h>
  99 #undef localtime_rz
 100 #undef mktime_z
 101 #undef posix2time_z
 102 #undef time2posix_z
 103 #undef timezone_t
 104 #undef tzalloc
 105 #undef tzfree
 106
 107 #include <sys/types.h>  /* for time_t */
 108 #include <stdio.h>
 109 #include <string.h>
 110 #include <limits.h>     /* for CHAR_BIT et al. */
 111 #include <stdlib.h>
 112
 113 #include <errno.h>
 114
 115 #ifndef ENAMETOOLONG
 116 # define ENAMETOOLONG EINVAL
 117 #endif
 118 #ifndef ENOTSUP
 119 # define ENOTSUP EINVAL
 120 #endif
 121 #ifndef EOVERFLOW
 122 # define EOVERFLOW EINVAL
 123 #endif
 124
 125 #if HAVE_GETTEXT
 126 #include <libintl.h>
 127 #endif /* HAVE_GETTEXT */
 128
 129 #if HAVE_SYS_WAIT_H
 130 #include <sys/wait.h>   /* for WIFEXITED and WEXITSTATUS */
 131 #endif /* HAVE_SYS_WAIT_H */
 132
 133 #ifndef WIFEXITED
 134 #define WIFEXITED(status)       (((status) & 0xff) == 0)
 135 #endif /* !defined WIFEXITED */
 136 #ifndef WEXITSTATUS
 137 #define WEXITSTATUS(status)     (((status) >> 8) & 0xff)
 138 #endif /* !defined WEXITSTATUS */
 139
 140 #if HAVE_UNISTD_H
 141 #include <unistd.h>     /* for F_OK, R_OK, and other POSIX goodness */
 142 #endif /* HAVE_UNISTD_H */
 143
 144 #ifndef HAVE_STRFTIME_L
 145 # if _POSIX_VERSION < 200809
 146 #  define HAVE_STRFTIME_L 0
 147 # else
 148 #  define HAVE_STRFTIME_L 1
 149 # endif
 150 #endif
 151
 152 #ifndef F_OK
 153 #define F_OK    0
 154 #endif /* !defined F_OK */
 155 #ifndef R_OK
 156 #define R_OK    4
 157 #endif /* !defined R_OK */
 158
 159 /* Unlike <ctype.h>'s isdigit, this also works if c < 0 | c > UCHAR_MAX. */
 160 #define is_digit(c) ((unsigned)(c) - '0' <= 9)
 161
 162 /*
 163 ** Define HAVE_STDINT_H's default value here, rather than at the
 164 ** start, since __GLIBC__ and INTMAX_MAX's values depend on
 165 ** previously-included files.  glibc 2.1 and Solaris 10 and later have
 166 ** stdint.h, even with pre-C99 compilers.
 167 */
 168 #ifndef HAVE_STDINT_H
 169 #define HAVE_STDINT_H \
 170    (199901 <= __STDC_VERSION__ \
 171     || 2 < __GLIBC__ + (1 <= __GLIBC_MINOR__)   \
 172     || __CYGWIN__ || INTMAX_MAX)
 173 #endif /* !defined HAVE_STDINT_H */
 174
 175 #if HAVE_STDINT_H
 176 #include <stdint.h>
 177 #endif /* !HAVE_STDINT_H */
 178
 179 #ifndef HAVE_INTTYPES_H
 180 # define HAVE_INTTYPES_H HAVE_STDINT_H
 181 #endif
 182 #if HAVE_INTTYPES_H
 183 # include <inttypes.h>
 184 #endif
 185
 186 /* Pre-C99 GCC compilers define __LONG_LONG_MAX__ instead of LLONG_MAX.  */
 187 #ifdef __LONG_LONG_MAX__
 188 # ifndef LLONG_MAX
 189 #  define LLONG_MAX __LONG_LONG_MAX__
 190 # endif
 191 # ifndef LLONG_MIN
 192 #  define LLONG_MIN (-1 - LLONG_MAX)
 193 # endif
 194 #endif
 195
 196 #ifndef INT_FAST64_MAX
 197 # ifdef LLONG_MAX
 198 typedef long long       int_fast64_t;
 199 #  define INT_FAST64_MIN LLONG_MIN
 200 #  define INT_FAST64_MAX LLONG_MAX
 201 # else
 202 #  if LONG_MAX >> 31 < 0xffffffff
 203 Please use a compiler that supports a 64-bit integer type (or wider);
 204 you may need to compile with "-DHAVE_STDINT_H".
 205 #  endif
 206 typedef long            int_fast64_t;
 207 #  define INT_FAST64_MIN LONG_MIN
 208 #  define INT_FAST64_MAX LONG_MAX
 209 # endif
 210 #endif
 211
 212 #ifndef PRIdFAST64
 213 # if INT_FAST64_MAX == LLONG_MAX
 214 #  define PRIdFAST64 "lld"
 215 # else
 216 #  define PRIdFAST64 "ld"
 217 # endif
 218 #endif
 219
 220 #ifndef SCNdFAST64
 221 # define SCNdFAST64 PRIdFAST64
 222 #endif
 223
 224 #ifndef INT_FAST32_MAX
 225 # if INT_MAX >> 31 == 0
 226 typedef long int_fast32_t;
 227 #  define INT_FAST32_MAX LONG_MAX
 228 #  define INT_FAST32_MIN LONG_MIN
 229 # else
 230 typedef int int_fast32_t;
 231 #  define INT_FAST32_MAX INT_MAX
 232 #  define INT_FAST32_MIN INT_MIN
 233 # endif
 234 #endif
 235
 236 #ifndef INTMAX_MAX
 237 # ifdef LLONG_MAX
 238 typedef long long intmax_t;
 239 #  define strtoimax strtoll
 240 #  define INTMAX_MAX LLONG_MAX
 241 #  define INTMAX_MIN LLONG_MIN
 242 # else
 243 typedef long intmax_t;
 244 #  define strtoimax strtol
 245 #  define INTMAX_MAX LONG_MAX
 246 #  define INTMAX_MIN LONG_MIN
 247 # endif
 248 #endif
 249
 250 #ifndef PRIdMAX
 251 # if INTMAX_MAX == LLONG_MAX
 252 #  define PRIdMAX "lld"
 253 # else
 254 #  define PRIdMAX "ld"
 255 # endif
 256 #endif
 257
 258 #ifndef UINT_FAST64_MAX
 259 # if defined ULLONG_MAX || defined __LONG_LONG_MAX__
 260 typedef unsigned long long uint_fast64_t;
 261 # else
 262 #  if ULONG_MAX >> 31 >> 1 < 0xffffffff
 263 Please use a compiler that supports a 64-bit integer type (or wider);
 264 you may need to compile with "-DHAVE_STDINT_H".
 265 #  endif
 266 typedef unsigned long   uint_fast64_t;
 267 # endif
 268 #endif
 269
 270 #ifndef UINTMAX_MAX
 271 # if defined ULLONG_MAX || defined __LONG_LONG_MAX__
 272 typedef unsigned long long uintmax_t;
 273 # else
 274 typedef unsigned long uintmax_t;
 275 # endif
 276 #endif
 277
 278 #ifndef PRIuMAX
 279 # if defined ULLONG_MAX || defined __LONG_LONG_MAX__
 280 #  define PRIuMAX "llu"
 281 # else
 282 #  define PRIuMAX "lu"
 283 # endif
 284 #endif
 285
 286 #ifndef INT32_MAX
 287 #define INT32_MAX 0x7fffffff
 288 #endif /* !defined INT32_MAX */
 289 #ifndef INT32_MIN
 290 #define INT32_MIN (-1 - INT32_MAX)
 291 #endif /* !defined INT32_MIN */
 292
 293 #ifndef SIZE_MAX
 294 #define SIZE_MAX ((size_t) -1)
 295 #endif
 296
 297 #if 2 < __GNUC__ + (96 <= __GNUC_MINOR__)
 298 # define ATTRIBUTE_CONST __attribute__ ((const))
 299 # define ATTRIBUTE_PURE __attribute__ ((__pure__))
 300 # define ATTRIBUTE_FORMAT(spec) __attribute__ ((__format__ spec))
 301 #else
 302 # define ATTRIBUTE_CONST /* empty */
 303 # define ATTRIBUTE_PURE /* empty */
 304 # define ATTRIBUTE_FORMAT(spec) /* empty */
 305 #endif
 306
 307 #if !defined _Noreturn && __STDC_VERSION__ < 201112
 308 # if 2 < __GNUC__ + (8 <= __GNUC_MINOR__)
 309 #  define _Noreturn __attribute__ ((__noreturn__))
 310 # else
 311 #  define _Noreturn
 312 # endif
 313 #endif
 314
 315 #if __STDC_VERSION__ < 199901 && !defined restrict
 316 # define restrict /* empty */
 317 #endif
 318
 319 /*
 320 ** Workarounds for compilers/systems.
 321 */
 322
 323 #ifndef EPOCH_LOCAL
 324 # define EPOCH_LOCAL 0
 325 #endif
 326 #ifndef EPOCH_OFFSET
 327 # define EPOCH_OFFSET 0
 328 #endif
 329
 330 /*
 331 ** Compile with -Dtime_tz=T to build the tz package with a private
 332 ** time_t type equivalent to T rather than the system-supplied time_t.
 333 ** This debugging feature can test unusual design decisions
 334 ** (e.g., time_t wider than 'long', or unsigned time_t) even on
 335 ** typical platforms.
 336 */
 337 #if defined time_tz || EPOCH_LOCAL || EPOCH_OFFSET != 0
 338 # ifdef LOCALTIME_IMPLEMENTATION
 339 static time_t sys_time(time_t *x) { return time(x); }
 340 # endif
 341
 342 typedef time_tz tz_time_t;
 343
 344 # undef  ctime
 345 # define ctime tz_ctime
 346 # undef  ctime_r
 347 # define ctime_r tz_ctime_r
 348 # undef  difftime
 349 # define difftime tz_difftime
 350 # undef  gmtime
 351 # define gmtime tz_gmtime
 352 # undef  gmtime_r
 353 # define gmtime_r tz_gmtime_r
 354 # undef  localtime
 355 # define localtime tz_localtime
 356 # undef  localtime_r
 357 # define localtime_r tz_localtime_r
 358 # undef  localtime_rz
 359 # define localtime_rz tz_localtime_rz
 360 # undef  mktime
 361 # define mktime tz_mktime
 362 # undef  mktime_z
 363 # define mktime_z tz_mktime_z
 364 # undef  offtime
 365 # define offtime tz_offtime
 366 # undef  posix2time
 367 # define posix2time tz_posix2time
 368 # undef  posix2time_z
 369 # define posix2time_z tz_posix2time_z
 370 # undef  time
 371 # define time tz_time
 372 # undef  time2posix
 373 # define time2posix tz_time2posix
 374 # undef  time2posix_z
 375 # define time2posix_z tz_time2posix_z
 376 # undef  time_t
 377 # define time_t tz_time_t
 378 # undef  timegm
 379 # define timegm tz_timegm
 380 # undef  timelocal
 381 # define timelocal tz_timelocal
 382 # undef  timeoff
 383 # define timeoff tz_timeoff
 384 # undef  tzalloc
 385 # define tzalloc tz_tzalloc
 386 # undef  tzfree
 387 # define tzfree tz_tzfree
 388 # undef  tzset
 389 # define tzset tz_tzset
 390 # undef  tzsetwall
 391 # define tzsetwall tz_tzsetwall
 392
 393 char *ctime(time_t const *);
 394 char *ctime_r(time_t const *, char *);
 395 double difftime(time_t, time_t);
 396 struct tm *gmtime(time_t const *);
 397 struct tm *gmtime_r(time_t const *restrict, struct tm *restrict);
 398 struct tm *localtime(time_t const *);
 399 struct tm *localtime_r(time_t const *restrict, struct tm *restrict);
 400 time_t mktime(struct tm *);
 401 time_t time(time_t *);
 402 void tzset(void);
 403 #endif
 404
 405 #if !HAVE_DECL_ASCTIME_R && !defined asctime_r
 406 extern char *asctime_r(struct tm const *restrict, char *restrict);
 407 #endif
 408
 409 #if !HAVE_POSIX_DECLS
 410 # ifdef USG_COMPAT
 411 #  ifndef timezone
 412 extern long timezone;
 413 #  endif
 414 #  ifndef daylight
 415 extern int daylight;
 416 #  endif
 417 # endif
 418 #endif
 419
 420 #if defined ALTZONE && !defined altzone
 421 extern long altzone;
 422 #endif
 423
 424 /*
 425 ** The STD_INSPIRED functions are similar, but most also need
 426 ** declarations if time_tz is defined.
 427 */
 428
 429 #ifdef STD_INSPIRED
 430 # if !defined tzsetwall || defined time_tz
 431 void tzsetwall(void);
 432 # endif
 433 # if !defined offtime || defined time_tz
 434 struct tm *offtime(time_t const *, long);
 435 # endif
 436 # if !defined timegm || defined time_tz
 437 time_t timegm(struct tm *);
 438 # endif
 439 # if !defined timelocal || defined time_tz
 440 time_t timelocal(struct tm *);
 441 # endif
 442 # if !defined timeoff || defined time_tz
 443 time_t timeoff(struct tm *, long);
 444 # endif
 445 # if !defined time2posix || defined time_tz
 446 time_t time2posix(time_t);
 447 # endif
 448 # if !defined posix2time || defined time_tz
 449 time_t posix2time(time_t);
 450 # endif
 451 #endif
 452
 453 /* Infer TM_ZONE on systems where this information is known, but suppress
 454    guessing if NO_TM_ZONE is defined.  Similarly for TM_GMTOFF.  */
 455 #if (defined __GLIBC__ \
 456      || defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ \
 457      || (defined __APPLE__ && defined __MACH__))
 458 # if !defined TM_GMTOFF && !defined NO_TM_GMTOFF
 459 #  define TM_GMTOFF tm_gmtoff
 460 # endif
 461 # if !defined TM_ZONE && !defined NO_TM_ZONE
 462 #  define TM_ZONE tm_zone
 463 # endif
 464 #endif
 465
 466 /*
 467 ** Define functions that are ABI compatible with NetBSD but have
 468 ** better prototypes.  NetBSD 6.1.4 defines a pointer type timezone_t
 469 ** and labors under the misconception that 'const timezone_t' is a
 470 ** pointer to a constant.  This use of 'const' is ineffective, so it
 471 ** is not done here.  What we call 'struct state' NetBSD calls
 472 ** 'struct __state', but this is a private name so it doesn't matter.
 473 */
 474 #if NETBSD_INSPIRED
 475 typedef struct state *timezone_t;
 476 struct tm *localtime_rz(timezone_t restrict, time_t const *restrict,
 477                         struct tm *restrict);
 478 time_t mktime_z(timezone_t restrict, struct tm *restrict);
 479 timezone_t tzalloc(char const *);
 480 void tzfree(timezone_t);
 481 # ifdef STD_INSPIRED
 482 #  if !defined posix2time_z || defined time_tz
 483 time_t posix2time_z(timezone_t, time_t) ATTRIBUTE_PURE;
 484 #  endif
 485 #  if !defined time2posix_z || defined time_tz
 486 time_t time2posix_z(timezone_t, time_t) ATTRIBUTE_PURE;
 487 #  endif
 488 # endif
 489 #endif
 490
 491 /*
 492 ** Finally, some convenience items.
 493 */
 494
 495 #if __STDC_VERSION__ < 199901
 496 # define true 1
 497 # define false 0
 498 # define bool int
 499 #else
 500 # include <stdbool.h>
 501 #endif
 502
 503 #define TYPE_BIT(type)  (sizeof (type) * CHAR_BIT)
 504 #define TYPE_SIGNED(type) (((type) -1) < 0)
 505 #define TWOS_COMPLEMENT(t) ((t) ~ (t) 0 < 0)
 506
 507 /* Max and min values of the integer type T, of which only the bottom
 508    B bits are used, and where the highest-order used bit is considered
 509    to be a sign bit if T is signed.  */
 510 #define MAXVAL(t, b)                                            \
 511   ((t) (((t) 1 << ((b) - 1 - TYPE_SIGNED(t)))                   \
 512         - 1 + ((t) 1 << ((b) - 1 - TYPE_SIGNED(t)))))
 513 #define MINVAL(t, b)                                            \
 514   ((t) (TYPE_SIGNED(t) ? - TWOS_COMPLEMENT(t) - MAXVAL(t, b) : 0))
 515
 516 /* The minimum and maximum finite time values.  This implementation
 517    assumes no padding if time_t is signed and either the compiler is
 518    pre-C11 or time_t is not one of the standard signed integer types.  */
 519 #if 201112 <= __STDC_VERSION__
 520 static time_t const time_t_min
 521   = (TYPE_SIGNED(time_t)
 522      ? _Generic((time_t) 0,
 523                 signed char: SCHAR_MIN, short: SHRT_MIN,
 524                 int: INT_MIN, long: LONG_MIN, long long: LLONG_MIN,
 525                 default: MINVAL(time_t, TYPE_BIT(time_t)))
 526      : 0);
 527 static time_t const time_t_max
 528   = (TYPE_SIGNED(time_t)
 529      ? _Generic((time_t) 0,
 530                 signed char: SCHAR_MAX, short: SHRT_MAX,
 531                 int: INT_MAX, long: LONG_MAX, long long: LLONG_MAX,
 532                 default: MAXVAL(time_t, TYPE_BIT(time_t)))
 533      : -1);
 534 #else
 535 static time_t const time_t_min = MINVAL(time_t, TYPE_BIT(time_t));
 536 static time_t const time_t_max = MAXVAL(time_t, TYPE_BIT(time_t));
 537 #endif
 538
 539 /*
 540 ** 302 / 1000 is log10(2.0) rounded up.
 541 ** Subtract one for the sign bit if the type is signed;
 542 ** add one for integer division truncation;
 543 ** add one more for a minus sign if the type is signed.
 544 */
 545 #define INT_STRLEN_MAXIMUM(type) \
 546         ((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + \
 547         1 + TYPE_SIGNED(type))
 548
 549 /*
 550 ** INITIALIZE(x)
 551 */
 552
 553 #ifdef lint
 554 # define INITIALIZE(x)  ((x) = 0)
 555 #else
 556 # define INITIALIZE(x)
 557 #endif
 558
 559 #ifndef UNINIT_TRAP
 560 # define UNINIT_TRAP 0
 561 #endif
 562
 563 /*
 564 ** For the benefit of GNU folk...
 565 ** '_(MSGID)' uses the current locale's message library string for MSGID.
 566 ** The default is to use gettext if available, and use MSGID otherwise.
 567 */
 568
 569 #if HAVE_GETTEXT
 570 #define _(msgid) gettext(msgid)
 571 #else /* !HAVE_GETTEXT */
 572 #define _(msgid) msgid
 573 #endif /* !HAVE_GETTEXT */
 574
 575 #if !defined TZ_DOMAIN && defined HAVE_GETTEXT
 576 # define TZ_DOMAIN "tz"
 577 #endif
 578
 579 #if HAVE_INCOMPATIBLE_CTIME_R
 580 #undef asctime_r
 581 #undef ctime_r
 582 char *asctime_r(struct tm const *, char *);
 583 char *ctime_r(time_t const *, char *);
 584 #endif /* HAVE_INCOMPATIBLE_CTIME_R */
 585
 586 /* Handy macros that are independent of tzfile implementation.  */
 587
 588 #define YEARSPERREPEAT          400     /* years before a Gregorian repeat */
 589
 590 #define SECSPERMIN      60
 591 #define MINSPERHOUR     60
 592 #define HOURSPERDAY     24
 593 #define DAYSPERWEEK     7
 594 #define DAYSPERNYEAR    365
 595 #define DAYSPERLYEAR    366
 596 #define SECSPERHOUR     (SECSPERMIN * MINSPERHOUR)
 597 #define SECSPERDAY      ((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
 598 #define MONSPERYEAR     12
 599
 600 #define TM_SUNDAY       0
 601 #define TM_MONDAY       1
 602 #define TM_TUESDAY      2
 603 #define TM_WEDNESDAY    3
 604 #define TM_THURSDAY     4
 605 #define TM_FRIDAY       5
 606 #define TM_SATURDAY     6
 607
 608 #define TM_JANUARY      0
 609 #define TM_FEBRUARY     1
 610 #define TM_MARCH        2
 611 #define TM_APRIL        3
 612 #define TM_MAY          4
 613 #define TM_JUNE         5
 614 #define TM_JULY         6
 615 #define TM_AUGUST       7
 616 #define TM_SEPTEMBER    8
 617 #define TM_OCTOBER      9
 618 #define TM_NOVEMBER     10
 619 #define TM_DECEMBER     11
 620
 621 #define TM_YEAR_BASE    1900
 622
 623 #define EPOCH_YEAR      1970
 624 #define EPOCH_WDAY      TM_THURSDAY
 625
 626 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
 627
 628 /*
 629 ** Since everything in isleap is modulo 400 (or a factor of 400), we know that
 630 **      isleap(y) == isleap(y % 400)
 631 ** and so
 632 **      isleap(a + b) == isleap((a + b) % 400)
 633 ** or
 634 **      isleap(a + b) == isleap(a % 400 + b % 400)
 635 ** This is true even if % means modulo rather than Fortran remainder
 636 ** (which is allowed by C89 but not C99).
 637 ** We use this to avoid addition overflow problems.
 638 */
 639
 640 #define isleap_sum(a, b)        isleap((a) % 400 + (b) % 400)
 641
 642
 643 /*
 644 ** The Gregorian year averages 365.2425 days, which is 31556952 seconds.
 645 */
 646
 647 #define AVGSECSPERYEAR          31556952L
 648 #define SECSPERREPEAT \
 649   ((int_fast64_t) YEARSPERREPEAT * (int_fast64_t) AVGSECSPERYEAR)
 650 #define SECSPERREPEAT_BITS      34      /* ceil(log2(SECSPERREPEAT)) */
 651
 652 #endif /* !defined PRIVATE_H */