tzfile.h

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#ifndef TZFILE_INCLUDED
#define TZFILE_INCLUDED
 
/* Copyright (c) 2004, 2025, Oracle and/or its affiliates.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
   This program is designed to work with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.
 
   This program 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, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
/*
   This file is based on public domain code from ftp://elsie.ncih.nist.gov/
   Initial source code is in the public domain, so clarified as of
   1996-06-05 by Arthur David Olson (arthur_david_olson@nih.gov).
*/
 
/*
  Information about time zone files.
*/
 
#ifndef TZDIR
#define TZDIR "/usr/share/zoneinfo" /* Time zone object file directory */
#endif                              /* !defined TZDIR */
 
/*
  Each file begins with. . .
*/
 
#define TZ_MAGIC "TZif"
 
struct tzhead {
  uchar tzh_magic[4];      /* TZ_MAGIC */
  uchar tzh_reserved[16];  /* reserved for future use */
  uchar tzh_ttisgmtcnt[4]; /* coded number of trans. time flags */
  uchar tzh_ttisstdcnt[4]; /* coded number of trans. time flags */
  uchar tzh_leapcnt[4];    /* coded number of leap seconds */
  uchar tzh_timecnt[4];    /* coded number of transition times */
  uchar tzh_typecnt[4];    /* coded number of local time types */
  uchar tzh_charcnt[4];    /* coded number of abbr. chars */
};
 
/*
  . . .followed by. . .
 
  tzh_timecnt (char [4])s               coded transition times a la time(2)
  tzh_timecnt (unsigned char)s          types of local time starting at above
  tzh_typecnt repetitions of
    one (char [4])                      coded UTC offset in seconds
    one (unsigned char)                 used to set tm_isdst
    one (unsigned char)                 that's an abbreviation list index
  tzh_charcnt (char)s                   '\0'-terminated zone abbreviations
  tzh_leapcnt repetitions of
    one (char [4])                      coded leap second transition times
    one (char [4])                      total correction after above
  tzh_ttisstdcnt (char)s                indexed by type; if true, transition
                                        time is standard time, if false,
                                        transition time is wall clock time
                                        if absent, transition times are
                                        assumed to be wall clock time
  tzh_ttisgmtcnt (char)s                indexed by type; if true, transition
                                        time is UTC, if false,
                                        transition time is local time
                                        if absent, transition times are
                                        assumed to be local time
*/
 
/*
  In the current implementation, we refuse to deal with files that
  exceed any of the limits below.
*/
 
#ifndef TZ_MAX_TIMES
/*
  The TZ_MAX_TIMES value below is enough to handle a bit more than a
  year's worth of solar time (corrected daily to the nearest second) or
  138 years of Pacific Presidential Election time
  (where there are three time zone transitions every fourth year).
*/
#define TZ_MAX_TIMES 370
#endif /* !defined TZ_MAX_TIMES */
 
#ifndef TZ_MAX_TYPES
/*
  Must be at least 14 for Europe/Riga as of Jan 12 1995,
  as noted by Earl Chew <earl@hpato.aus.hp.com>.
*/
#define TZ_MAX_TYPES 20 /* Maximum number of local time types */
#endif                  /* !defined TZ_MAX_TYPES */
 
#ifndef TZ_MAX_CHARS
#define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */
                        /* (limited by what unsigned chars can hold) */
#endif                  /* !defined TZ_MAX_CHARS */
 
#ifndef TZ_MAX_LEAPS
#define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */
#endif                  /* !defined TZ_MAX_LEAPS */
 
#ifndef TZ_MAX_REV_RANGES
#define TZ_MAX_REV_RANGES (TZ_MAX_TIMES + TZ_MAX_LEAPS + 2)
#endif
 
#define TM_YEAR_BASE 1900
 
#define EPOCH_YEAR 1970
 
/*
  Accurate only for the past couple of centuries,
  that will probably do.
*/
 
#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
 
#endif