1/* Layout and location of TZif files. */ 2 3#ifndef TZFILE_H 4#define TZFILE_H 5 6 7/* 8** This file is in the public domain, so clarified as of 9** 1996-06-05 by Arthur David Olson. 10** 11** $FreeBSD$ 12*/ 13 14/* 15** This header is for use ONLY with the time conversion code. 16** There is no guarantee that it will remain unchanged, 17** or that it will remain at all. 18** Do NOT copy it to any system include directory. 19** Thank you! 20*/ 21 22/* 23** Information about time zone files. 24*/ 25 26#ifndef TZDEFRULES 27# define TZDEFRULES "posixrules" 28#endif /* !defined TZDEFRULES */ 29 30 31/* See Internet RFC 8536 for more details about the following format. */ 32 33/* 34** Each file begins with. . . 35*/ 36 37#define TZ_MAGIC "TZif" 38 39struct tzhead { 40 char tzh_magic[4]; /* TZ_MAGIC */ 41 char tzh_version[1]; /* '\0' or '2'-'4' as of 2021 */ 42 char tzh_reserved[15]; /* reserved; must be zero */ 43 char tzh_ttisutcnt[4]; /* coded number of trans. time flags */ 44 char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */ 45 char tzh_leapcnt[4]; /* coded number of leap seconds */ 46 char tzh_timecnt[4]; /* coded number of transition times */ 47 char tzh_typecnt[4]; /* coded number of local time types */ 48 char tzh_charcnt[4]; /* coded number of abbr. chars */ 49}; 50 51/* 52** . . .followed by. . . 53** 54** tzh_timecnt (char [4])s coded transition times a la time(2) 55** tzh_timecnt (unsigned char)s types of local time starting at above 56** tzh_typecnt repetitions of 57** one (char [4]) coded UT offset in seconds 58** one (unsigned char) used to set tm_isdst 59** one (unsigned char) that's an abbreviation list index 60** tzh_charcnt (char)s '\0'-terminated zone abbreviations 61** tzh_leapcnt repetitions of 62** one (char [4]) coded leap second transition times 63** one (char [4]) total correction after above 64** tzh_ttisstdcnt (char)s indexed by type; if 1, transition 65** time is standard time, if 0, 66** transition time is local (wall clock) 67** time; if absent, transition times are 68** assumed to be local time 69** tzh_ttisutcnt (char)s indexed by type; if 1, transition 70** time is UT, if 0, transition time is 71** local time; if absent, transition 72** times are assumed to be local time. 73** When this is 1, the corresponding 74** std/wall indicator must also be 1. 75*/ 76 77/* 78** If tzh_version is '2' or greater, the above is followed by a second instance 79** of tzhead and a second instance of the data in which each coded transition 80** time uses 8 rather than 4 chars, 81** then a POSIX-TZ-environment-variable-style string for use in handling 82** instants after the last transition time stored in the file 83** (with nothing between the newlines if there is no POSIX.1-2017 84** representation for such instants). 85** 86** If tz_version is '3' or greater, the above is extended as follows. 87** First, the TZ string's hour offset may range from -167 88** through 167 as compared to the POSIX-required 0 through 24. 89** Second, its DST start time may be January 1 at 00:00 and its stop 90** time December 31 at 24:00 plus the difference between DST and 91** standard time, indicating DST all year. 92*/ 93 94/* 95** In the current implementation, "tzset()" refuses to deal with files that 96** exceed any of the limits below. 97*/ 98 99#ifndef TZ_MAX_TIMES 100/* This must be at least 242 for Europe/London with 'zic -b fat'. */ 101# define TZ_MAX_TIMES 2000 102#endif /* !defined TZ_MAX_TIMES */ 103 104#ifndef TZ_MAX_TYPES 105/* This must be at least 18 for Europe/Vilnius with 'zic -b fat'. */ 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/* This must be at least 40 for America/Anchorage. */ 111# define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */ 112 /* (limited by what unsigned chars can hold) */ 113#endif /* !defined TZ_MAX_CHARS */ 114 115#ifndef TZ_MAX_LEAPS 116/* This must be at least 27 for leap seconds from 1972 through mid-2023. 117 There's a plan to discontinue leap seconds by 2035. */ 118# define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */ 119#endif /* !defined TZ_MAX_LEAPS */ 120 121#endif /* !defined TZFILE_H */ 122