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