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 TZDEFRULES 25# define TZDEFRULES "posixrules" 26#endif /* !defined TZDEFRULES */ 27 28 29/* See Internet RFC 8536 for more details about the following format. */ 30 31/* 32** Each file begins with. . . 33*/ 34 35#define TZ_MAGIC "TZif" 36 37struct tzhead { 38 char tzh_magic[4]; /* TZ_MAGIC */ 39 char tzh_version[1]; /* '\0' or '2'-'4' as of 2021 */ 40 char tzh_reserved[15]; /* reserved; must be zero */ 41 char tzh_ttisutcnt[4]; /* coded number of trans. time flags */ 42 char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */ 43 char tzh_leapcnt[4]; /* coded number of leap seconds */ 44 char tzh_timecnt[4]; /* coded number of transition times */ 45 char tzh_typecnt[4]; /* coded number of local time types */ 46 char tzh_charcnt[4]; /* coded number of abbr. chars */ 47}; 48 49/* 50** . . .followed by. . . 51** 52** tzh_timecnt (char [4])s coded transition times a la time(2) 53** tzh_timecnt (unsigned char)s types of local time starting at above 54** tzh_typecnt repetitions of 55** one (char [4]) coded UT offset in seconds 56** one (unsigned char) used to set tm_isdst 57** one (unsigned char) that's an abbreviation list index 58** tzh_charcnt (char)s '\0'-terminated zone abbreviations 59** tzh_leapcnt repetitions of 60** one (char [4]) coded leap second transition times 61** one (char [4]) total correction after above 62** tzh_ttisstdcnt (char)s indexed by type; if 1, transition 63** time is standard time, if 0, 64** transition time is local (wall clock) 65** time; if absent, transition times are 66** assumed to be local time 67** tzh_ttisutcnt (char)s indexed by type; if 1, transition 68** time is UT, if 0, transition time is 69** local time; if absent, transition 70** times are assumed to be local time. 71** When this is 1, the corresponding 72** std/wall indicator must also be 1. 73*/ 74 75/* 76** If tzh_version is '2' or greater, the above is followed by a second instance 77** of tzhead and a second instance of the data in which each coded transition 78** time uses 8 rather than 4 chars, 79** then a POSIX-TZ-environment-variable-style string for use in handling 80** instants after the last transition time stored in the file 81** (with nothing between the newlines if there is no POSIX.1-2017 82** representation for such instants). 83** 84** If tz_version is '3' or greater, the above is extended as follows. 85** First, the TZ string's hour offset may range from -167 86** through 167 as compared to the POSIX-required 0 through 24. 87** Second, its DST start time may be January 1 at 00:00 and its stop 88** time December 31 at 24:00 plus the difference between DST and 89** standard time, indicating DST all year. 90*/ 91 92/* 93** In the current implementation, "tzset()" refuses to deal with files that 94** exceed any of the limits below. 95*/ 96 97#ifndef TZ_MAX_TIMES 98/* This must be at least 242 for Europe/London with 'zic -b fat'. */ 99# define TZ_MAX_TIMES 2000 100#endif /* !defined TZ_MAX_TIMES */ 101 102#ifndef TZ_MAX_TYPES 103/* This must be at least 18 for Europe/Vilnius with 'zic -b fat'. */ 104# define TZ_MAX_TYPES 256 /* Limited by what (unsigned char)'s can hold */ 105#endif /* !defined TZ_MAX_TYPES */ 106 107#ifndef TZ_MAX_CHARS 108/* This must be at least 40 for America/Anchorage. */ 109# define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */ 110 /* (limited by what unsigned chars can hold) */ 111#endif /* !defined TZ_MAX_CHARS */ 112 113#ifndef TZ_MAX_LEAPS 114/* This must be at least 27 for leap seconds from 1972 through mid-2023. 115 There's a plan to discontinue leap seconds by 2035. */ 116# define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */ 117#endif /* !defined TZ_MAX_LEAPS */ 118 119#endif /* !defined TZFILE_H */ 120