include/tzfile.h

   1 /*      $NetBSD: tzfile.h,v 1.8 2015/07/11 16:40:53 christos Exp $      */
   2
   3 #ifndef _TZFILE_H_
   4 #define _TZFILE_H_
   5
   6 /*
   7 ** This file is in the public domain, so clarified as of
   8 ** 1996-06-05 by Arthur David Olson.
   9 */
  10
  11 /*
  12 ** This header is for use ONLY with the time conversion code.
  13 ** There is no guarantee that it will remain unchanged,
  14 ** or that it will remain at all.
  15 ** Do NOT copy it to any system include directory.
  16 ** Thank you!
  17 */
  18
  19 /*
  20 ** Information about time zone files.
  21 */
  22
  23 #ifndef TZDIR           /* Time zone object file directory */
  24 #define TZDIR           "/usr/share/zoneinfo"
  25 #endif /* !defined TZDIR */
  26
  27 #ifndef TZDEFAULT
  28 #define TZDEFAULT       "/etc/localtime"
  29 #endif /* !defined TZDEFAULT */
  30
  31 #ifndef TZDEFRULES
  32 #define TZDEFRULES      "posixrules"
  33 #endif /* !defined TZDEFRULES */
  34
  35 /*
  36 ** Each file begins with. . .
  37 */
  38
  39 #define TZ_MAGIC        "TZif"
  40
  41 struct tzhead {
  42         char    tzh_magic[4];           /* TZ_MAGIC */
  43         char    tzh_version[1];         /* '\0' or '2' or '3' as of 2013 */
  44         char    tzh_reserved[15];       /* reserved; must be zero */
  45         char    tzh_ttisgmtcnt[4];      /* coded number of trans. time flags */
  46         char    tzh_ttisstdcnt[4];      /* coded number of trans. time flags */
  47         char    tzh_leapcnt[4];         /* coded number of leap seconds */
  48         char    tzh_timecnt[4];         /* coded number of transition times */
  49         char    tzh_typecnt[4];         /* coded number of local time types */
  50         char    tzh_charcnt[4];         /* coded number of abbr. chars */
  51 };
  52
  53 /*
  54 ** . . .followed by. . .
  55 **
  56 **      tzh_timecnt (char [4])s         coded transition times a la time(2)
  57 **      tzh_timecnt (unsigned char)s    types of local time starting at above
  58 **      tzh_typecnt repetitions of
  59 **              one (char [4])          coded UT offset in seconds
  60 **              one (unsigned char)     used to set tm_isdst
  61 **              one (unsigned char)     that's an abbreviation list index
  62 **      tzh_charcnt (char)s             '\0'-terminated zone abbreviations
  63 **      tzh_leapcnt repetitions of
  64 **              one (char [4])          coded leap second transition times
  65 **              one (char [4])          total correction after above
  66 **      tzh_ttisstdcnt (char)s          indexed by type; if 1, transition
  67 **                                      time is standard time, if 0,
  68 **                                      transition time is wall clock time
  69 **                                      if absent, transition times are
  70 **                                      assumed to be wall clock time
  71 **      tzh_ttisgmtcnt (char)s          indexed by type; if 1, transition
  72 **                                      time is UT, if 0,
  73 **                                      transition time is local time
  74 **                                      if absent, transition times are
  75 **                                      assumed to be local time
  76 */
  77
  78 /*
  79 ** If tzh_version is '2' or greater, the above is followed by a second instance
  80 ** of tzhead and a second instance of the data in which each coded transition
  81 ** time uses 8 rather than 4 chars,
  82 ** then a POSIX-TZ-environment-variable-style string for use in handling
  83 ** instants after the last transition time stored in the file
  84 ** (with nothing between the newlines if there is no POSIX representation for
  85 ** such instants).
  86 **
  87 ** If tz_version is '3' or greater, the above is extended as follows.
  88 ** First, the POSIX TZ string's hour offset may range from -167
  89 ** through 167 as compared to the POSIX-required 0 through 24.
  90 ** Second, its DST start time may be January 1 at 00:00 and its stop
  91 ** time December 31 at 24:00 plus the difference between DST and
  92 ** standard time, indicating DST all year.
  93 */
  94
  95 /*
  96 ** In the current implementation, "tzset()" refuses to deal with files that
  97 ** exceed any of the limits below.
  98 */
  99
 100 #ifndef TZ_MAX_TIMES
 101 #define TZ_MAX_TIMES    2000
 102 #endif /* !defined TZ_MAX_TIMES */
 103
 104 #ifndef TZ_MAX_TYPES
 105 /* This must be at least 17 for Europe/Samara and Europe/Vilnius.  */
 106 #define TZ_MAX_TYPES    256 /* Limited by what (unsigned char)'s can hold */
 107 #endif /* !defined TZ_MAX_TYPES */
 108
 109 #ifndef TZ_MAX_CHARS
 110 #define TZ_MAX_CHARS    50      /* Maximum number of abbreviation characters */
 111                                 /* (limited by what unsigned chars can hold) */
 112 #endif /* !defined TZ_MAX_CHARS */
 113
 114 #ifndef TZ_MAX_LEAPS
 115 #define TZ_MAX_LEAPS    50      /* Maximum number of leap second corrections */
 116 #endif /* !defined TZ_MAX_LEAPS */
 117
 118 #define SECSPERMIN      60
 119 #define MINSPERHOUR     60
 120 #define HOURSPERDAY     24
 121 #define DAYSPERWEEK     7
 122 #define DAYSPERNYEAR    365
 123 #define DAYSPERLYEAR    366
 124 #define SECSPERHOUR     (SECSPERMIN * MINSPERHOUR)
 125 #define SECSPERDAY      ((int_fast32_t) SECSPERHOUR * HOURSPERDAY)
 126 #define MONSPERYEAR     12
 127
 128 #define TM_SUNDAY       0
 129 #define TM_MONDAY       1
 130 #define TM_TUESDAY      2
 131 #define TM_WEDNESDAY    3
 132 #define TM_THURSDAY     4
 133 #define TM_FRIDAY       5
 134 #define TM_SATURDAY     6
 135
 136 #define TM_JANUARY      0
 137 #define TM_FEBRUARY     1
 138 #define TM_MARCH        2
 139 #define TM_APRIL        3
 140 #define TM_MAY          4
 141 #define TM_JUNE         5
 142 #define TM_JULY         6
 143 #define TM_AUGUST       7
 144 #define TM_SEPTEMBER    8
 145 #define TM_OCTOBER      9
 146 #define TM_NOVEMBER     10
 147 #define TM_DECEMBER     11
 148
 149 #define TM_YEAR_BASE    1900
 150
 151 #define EPOCH_YEAR      1970
 152 #define EPOCH_WDAY      TM_THURSDAY
 153
 154 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
 155
 156 /*
 157 ** Since everything in isleap is modulo 400 (or a factor of 400), we know that
 158 **      isleap(y) == isleap(y % 400)
 159 ** and so
 160 **      isleap(a + b) == isleap((a + b) % 400)
 161 ** or
 162 **      isleap(a + b) == isleap(a % 400 + b % 400)
 163 ** This is true even if % means modulo rather than Fortran remainder
 164 ** (which is allowed by C89 but not C99).
 165 ** We use this to avoid addition overflow problems.
 166 */
 167
 168 #define isleap_sum(a, b)        isleap((a) % 400 + (b) % 400)
 169
 170 #endif /* !defined _TZFILE_H_ */