src/timezone/tzfile.h

   1 #ifndef TZFILE_H
   2 #define TZFILE_H
   3
   4 /*
   5  * This file is in the public domain, so clarified as of
   6  * 1996-06-05 by Arthur David Olson.
   7  *
   8  * IDENTIFICATION
   9  *        src/timezone/tzfile.h
  10  */
  11
  12 /*
  13  * This header is for use ONLY with the time conversion code.
  14  * There is no guarantee that it will remain unchanged,
  15  * or that it will remain at all.
  16  * Do NOT copy it to any system include directory.
  17  * Thank you!
  18  */
  19
  20 /*
  21  * Information about time zone files.
  22  */
  23
  24 #define TZDEFAULT       "localtime"
  25 #define TZDEFRULES      "posixrules"
  26
  27 /*
  28  * Each file begins with. . .
  29  */
  30
  31 #define TZ_MAGIC        "TZif"
  32
  33 struct tzhead
  34 {
  35         char            tzh_magic[4];   /* TZ_MAGIC */
  36         char            tzh_version[1]; /* '\0' or '2' or '3' as of 2013 */
  37         char            tzh_reserved[15];               /* reserved; must be zero */
  38         char            tzh_ttisgmtcnt[4];              /* coded number of trans. time flags */
  39         char            tzh_ttisstdcnt[4];              /* coded number of trans. time flags */
  40         char            tzh_leapcnt[4]; /* coded number of leap seconds */
  41         char            tzh_timecnt[4]; /* coded number of transition times */
  42         char            tzh_typecnt[4]; /* coded number of local time types */
  43         char            tzh_charcnt[4]; /* coded number of abbr. chars */
  44 };
  45
  46 /*
  47  * . . .followed by. . .
  48  *
  49  *      tzh_timecnt (char [4])s         coded transition times a la time(2)
  50  *      tzh_timecnt (unsigned char)s    types of local time starting at above
  51  *      tzh_typecnt repetitions of
  52  *              one (char [4])          coded UT offset in seconds
  53  *              one (unsigned char) used to set tm_isdst
  54  *              one (unsigned char) that's an abbreviation list index
  55  *      tzh_charcnt (char)s             '\0'-terminated zone abbreviations
  56  *      tzh_leapcnt repetitions of
  57  *              one (char [4])          coded leap second transition times
  58  *              one (char [4])          total correction after above
  59  *      tzh_ttisstdcnt (char)s          indexed by type; if 1, transition
  60  *                                      time is standard time, if 0,
  61  *                                      transition time is wall clock time
  62  *                                      if absent, transition times are
  63  *                                      assumed to be wall clock time
  64  *      tzh_ttisgmtcnt (char)s          indexed by type; if 1, transition
  65  *                                      time is UT, if 0,
  66  *                                      transition time is local time
  67  *                                      if absent, transition times are
  68  *                                      assumed to be local time
  69  */
  70
  71 /*
  72  * If tzh_version is '2' or greater, the above is followed by a second instance
  73  * of tzhead and a second instance of the data in which each coded transition
  74  * time uses 8 rather than 4 chars,
  75  * then a POSIX-TZ-environment-variable-style string for use in handling
  76  * instants after the last transition time stored in the file
  77  * (with nothing between the newlines if there is no POSIX representation for
  78  * such instants).
  79  *
  80  * If tz_version is '3' or greater, the above is extended as follows.
  81  * First, the POSIX TZ string's hour offset may range from -167
  82  * through 167 as compared to the POSIX-required 0 through 24.
  83  * Second, its DST start time may be January 1 at 00:00 and its stop
  84  * time December 31 at 24:00 plus the difference between DST and
  85  * standard time, indicating DST all year.
  86  */
  87
  88 /*
  89  * In the current implementation, "tzset()" refuses to deal with files that
  90  * exceed any of the limits below.
  91  */
  92
  93 #define TZ_MAX_TIMES    2000
  94
  95 /* This must be at least 17 for Europe/Samara and Europe/Vilnius.  */
  96 #define TZ_MAX_TYPES    256             /* Limited by what (unsigned char)'s can hold */
  97
  98 #define TZ_MAX_CHARS    50              /* Maximum number of abbreviation characters */
  99  /* (limited by what unsigned chars can hold) */
 100
 101 #define TZ_MAX_LEAPS    50              /* Maximum number of leap second corrections */
 102
 103 #define SECSPERMIN      60
 104 #define MINSPERHOUR 60
 105 #define HOURSPERDAY 24
 106 #define DAYSPERWEEK 7
 107 #define DAYSPERNYEAR    365
 108 #define DAYSPERLYEAR    366
 109 #define SECSPERHOUR (SECSPERMIN * MINSPERHOUR)
 110 #define SECSPERDAY      ((int32) SECSPERHOUR * HOURSPERDAY)
 111 #define MONSPERYEAR 12
 112
 113 #define TM_SUNDAY       0
 114 #define TM_MONDAY       1
 115 #define TM_TUESDAY      2
 116 #define TM_WEDNESDAY    3
 117 #define TM_THURSDAY 4
 118 #define TM_FRIDAY       5
 119 #define TM_SATURDAY 6
 120
 121 #define TM_JANUARY      0
 122 #define TM_FEBRUARY 1
 123 #define TM_MARCH        2
 124 #define TM_APRIL        3
 125 #define TM_MAY          4
 126 #define TM_JUNE         5
 127 #define TM_JULY         6
 128 #define TM_AUGUST       7
 129 #define TM_SEPTEMBER    8
 130 #define TM_OCTOBER      9
 131 #define TM_NOVEMBER 10
 132 #define TM_DECEMBER 11
 133
 134 #define TM_YEAR_BASE    1900
 135
 136 #define EPOCH_YEAR      1970
 137 #define EPOCH_WDAY      TM_THURSDAY
 138
 139 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
 140
 141 /*
 142  * Since everything in isleap is modulo 400 (or a factor of 400), we know that
 143  *        isleap(y) == isleap(y % 400)
 144  * and so
 145  *        isleap(a + b) == isleap((a + b) % 400)
 146  * or
 147  *        isleap(a + b) == isleap(a % 400 + b % 400)
 148  * This is true even if % means modulo rather than Fortran remainder
 149  * (which is allowed by C89 but not C99).
 150  * We use this to avoid addition overflow problems.
 151  */
 152
 153 #define isleap_sum(a, b)        isleap((a) % 400 + (b) % 400)
 154
 155 #endif   /* !defined TZFILE_H */