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 TZDIR 27 # define TZDIR "/usr/share/zoneinfo" /* Time zone object file directory */ 28 #endif /* !defined TZDIR */ 29 30 #ifndef TZDEFAULT 31 # define TZDEFAULT "/etc/localtime" 32 #endif /* !defined TZDEFAULT */ 33 34 #ifndef TZDEFRULES 35 # define TZDEFRULES "posixrules" 36 #endif /* !defined TZDEFRULES */ 37 38 39 /* See Internet RFC 8536 for more details about the following format. */ 40 41 /* 42 ** Each file begins with. . . 43 */ 44 45 #define TZ_MAGIC "TZif" 46 47 struct tzhead { 48 char tzh_magic[4]; /* TZ_MAGIC */ 49 char tzh_version[1]; /* '\0' or '2'-'4' as of 2021 */ 50 char tzh_reserved[15]; /* reserved; must be zero */ 51 char tzh_ttisutcnt[4]; /* coded number of trans. time flags */ 52 char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */ 53 char tzh_leapcnt[4]; /* coded number of leap seconds */ 54 char tzh_timecnt[4]; /* coded number of transition times */ 55 char tzh_typecnt[4]; /* coded number of local time types */ 56 char tzh_charcnt[4]; /* coded number of abbr. chars */ 57 }; 58 59 /* 60 ** . . .followed by. . . 61 ** 62 ** tzh_timecnt (char [4])s coded transition times a la time(2) 63 ** tzh_timecnt (unsigned char)s types of local time starting at above 64 ** tzh_typecnt repetitions of 65 ** one (char [4]) coded UT offset in seconds 66 ** one (unsigned char) used to set tm_isdst 67 ** one (unsigned char) that's an abbreviation list index 68 ** tzh_charcnt (char)s '\0'-terminated zone abbreviations 69 ** tzh_leapcnt repetitions of 70 ** one (char [4]) coded leap second transition times 71 ** one (char [4]) total correction after above 72 ** tzh_ttisstdcnt (char)s indexed by type; if 1, transition 73 ** time is standard time, if 0, 74 ** transition time is local (wall clock) 75 ** time; if absent, transition times are 76 ** assumed to be local time 77 ** tzh_ttisutcnt (char)s indexed by type; if 1, transition 78 ** time is UT, if 0, transition time is 79 ** local time; if absent, transition 80 ** times are assumed to be local time. 81 ** When this is 1, the corresponding 82 ** std/wall indicator must also be 1. 83 */ 84 85 /* 86 ** If tzh_version is '2' or greater, the above is followed by a second instance 87 ** of tzhead and a second instance of the data in which each coded transition 88 ** time uses 8 rather than 4 chars, 89 ** then a POSIX-TZ-environment-variable-style string for use in handling 90 ** instants after the last transition time stored in the file 91 ** (with nothing between the newlines if there is no POSIX representation for 92 ** such instants). 93 ** 94 ** If tz_version is '3' or greater, the above is extended as follows. 95 ** First, the POSIX TZ string's hour offset may range from -167 96 ** through 167 as compared to the POSIX-required 0 through 24. 97 ** Second, its DST start time may be January 1 at 00:00 and its stop 98 ** time December 31 at 24:00 plus the difference between DST and 99 ** standard time, indicating DST all year. 100 */ 101 102 /* 103 ** In the current implementation, "tzset()" refuses to deal with files that 104 ** exceed any of the limits below. 105 */ 106 107 #ifndef TZ_MAX_TIMES 108 /* This must be at least 242 for Europe/London with 'zic -b fat'. */ 109 # define TZ_MAX_TIMES 2000 110 #endif /* !defined TZ_MAX_TIMES */ 111 112 #ifndef TZ_MAX_TYPES 113 /* This must be at least 18 for Europe/Vilnius with 'zic -b fat'. */ 114 # define TZ_MAX_TYPES 256 /* Limited by what (unsigned char)'s can hold */ 115 #endif /* !defined TZ_MAX_TYPES */ 116 117 #ifndef TZ_MAX_CHARS 118 /* This must be at least 40 for America/Anchorage. */ 119 # define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */ 120 /* (limited by what unsigned chars can hold) */ 121 #endif /* !defined TZ_MAX_CHARS */ 122 123 #ifndef TZ_MAX_LEAPS 124 /* This must be at least 27 for leap seconds from 1972 through mid-2023. 125 There's a plan to discontinue leap seconds by 2035. */ 126 # define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */ 127 #endif /* !defined TZ_MAX_LEAPS */ 128 129 #endif /* !defined TZFILE_H */ 130