1 /* Layout and location of TZif files. */ 2 3 #ifndef TZFILE_H 4 5 #define TZFILE_H 6 7 /* 8 ** This file is in the public domain, so clarified as of 9 ** 1996-06-05 by Arthur David Olson. 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 #ifndef TZDIR 25 #define TZDIR "/usr/share/zoneinfo" /* Time zone object file directory */ 26 #endif /* !defined TZDIR */ 27 28 #ifndef TZDEFAULT 29 #define TZDEFAULT "/etc/localtime" 30 #endif /* !defined TZDEFAULT */ 31 32 #ifndef TZDEFRULES 33 #define TZDEFRULES "posixrules" 34 #endif /* !defined TZDEFRULES */ 35 36 37 /* See Internet RFC 8536 for more details about the following format. */ 38 39 /* 40 ** Each file begins with. . . 41 */ 42 43 #define TZ_MAGIC "TZif" 44 45 struct tzhead { 46 char tzh_magic[4]; /* TZ_MAGIC */ 47 char tzh_version[1]; /* '\0' or '2'-'4' as of 2021 */ 48 char tzh_reserved[15]; /* reserved; must be zero */ 49 char tzh_ttisutcnt[4]; /* coded number of trans. time flags */ 50 char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */ 51 char tzh_leapcnt[4]; /* coded number of leap seconds */ 52 char tzh_timecnt[4]; /* coded number of transition times */ 53 char tzh_typecnt[4]; /* coded number of local time types */ 54 char tzh_charcnt[4]; /* coded number of abbr. chars */ 55 }; 56 57 /* 58 ** . . .followed by. . . 59 ** 60 ** tzh_timecnt (char [4])s coded transition times a la time(2) 61 ** tzh_timecnt (unsigned char)s types of local time starting at above 62 ** tzh_typecnt repetitions of 63 ** one (char [4]) coded UT offset in seconds 64 ** one (unsigned char) used to set tm_isdst 65 ** one (unsigned char) that's an abbreviation list index 66 ** tzh_charcnt (char)s '\0'-terminated zone abbreviations 67 ** tzh_leapcnt repetitions of 68 ** one (char [4]) coded leap second transition times 69 ** one (char [4]) total correction after above 70 ** tzh_ttisstdcnt (char)s indexed by type; if 1, transition 71 ** time is standard time, if 0, 72 ** transition time is local (wall clock) 73 ** time; if absent, transition times are 74 ** assumed to be local time 75 ** tzh_ttisutcnt (char)s indexed by type; if 1, transition 76 ** time is UT, if 0, transition time is 77 ** local time; if absent, transition 78 ** times are assumed to be local time. 79 ** When this is 1, the corresponding 80 ** std/wall indicator must also be 1. 81 */ 82 83 /* 84 ** If tzh_version is '2' or greater, the above is followed by a second instance 85 ** of tzhead and a second instance of the data in which each coded transition 86 ** time uses 8 rather than 4 chars, 87 ** then a POSIX-TZ-environment-variable-style string for use in handling 88 ** instants after the last transition time stored in the file 89 ** (with nothing between the newlines if there is no POSIX representation for 90 ** such instants). 91 ** 92 ** If tz_version is '3' or greater, the above is extended as follows. 93 ** First, the POSIX TZ string's hour offset may range from -167 94 ** through 167 as compared to the POSIX-required 0 through 24. 95 ** Second, its DST start time may be January 1 at 00:00 and its stop 96 ** time December 31 at 24:00 plus the difference between DST and 97 ** standard time, indicating DST all year. 98 */ 99 100 /* 101 ** In the current implementation, "tzset()" refuses to deal with files that 102 ** exceed any of the limits below. 103 */ 104 105 #ifndef TZ_MAX_TIMES 106 #define TZ_MAX_TIMES 2000 107 #endif /* !defined TZ_MAX_TIMES */ 108 109 #ifndef TZ_MAX_TYPES 110 /* This must be at least 17 for Europe/Samara and Europe/Vilnius. */ 111 #define TZ_MAX_TYPES 256 /* Limited by what (unsigned char)'s can hold */ 112 #endif /* !defined TZ_MAX_TYPES */ 113 114 #ifndef TZ_MAX_CHARS 115 #define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */ 116 /* (limited by what unsigned chars can hold) */ 117 #endif /* !defined TZ_MAX_CHARS */ 118 119 #ifndef TZ_MAX_LEAPS 120 #define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */ 121 #endif /* !defined TZ_MAX_LEAPS */ 122 123 #define SECSPERMIN 60 124 #define MINSPERHOUR 60 125 #define HOURSPERDAY 24 126 #define DAYSPERWEEK 7 127 #define DAYSPERNYEAR 365 128 #define DAYSPERLYEAR 366 129 #define SECSPERHOUR (SECSPERMIN * MINSPERHOUR) 130 #define SECSPERDAY ((int_fast32_t) SECSPERHOUR * HOURSPERDAY) 131 #define MONSPERYEAR 12 132 133 #define TM_SUNDAY 0 134 #define TM_MONDAY 1 135 #define TM_TUESDAY 2 136 #define TM_WEDNESDAY 3 137 #define TM_THURSDAY 4 138 #define TM_FRIDAY 5 139 #define TM_SATURDAY 6 140 141 #define TM_JANUARY 0 142 #define TM_FEBRUARY 1 143 #define TM_MARCH 2 144 #define TM_APRIL 3 145 #define TM_MAY 4 146 #define TM_JUNE 5 147 #define TM_JULY 6 148 #define TM_AUGUST 7 149 #define TM_SEPTEMBER 8 150 #define TM_OCTOBER 9 151 #define TM_NOVEMBER 10 152 #define TM_DECEMBER 11 153 154 #define TM_YEAR_BASE 1900 155 156 #define EPOCH_YEAR 1970 157 #define EPOCH_WDAY TM_THURSDAY 158 159 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0)) 160 161 /* 162 ** Since everything in isleap is modulo 400 (or a factor of 400), we know that 163 ** isleap(y) == isleap(y % 400) 164 ** and so 165 ** isleap(a + b) == isleap((a + b) % 400) 166 ** or 167 ** isleap(a + b) == isleap(a % 400 + b % 400) 168 ** This is true even if % means modulo rather than Fortran remainder 169 ** (which is allowed by C89 but not C99). 170 ** We use this to avoid addition overflow problems. 171 */ 172 173 #define isleap_sum(a, b) isleap((a) % 400 + (b) % 400) 174 175 #endif /* !defined TZFILE_H */ 176