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 * IDENTIFICATION 12 * src/timezone/tzfile.h 13 */ 14 15 /* 16 * This header is for use ONLY with the time conversion code. 17 * There is no guarantee that it will remain unchanged, 18 * or that it will remain at all. 19 * Do NOT copy it to any system include directory. 20 * Thank you! 21 */ 22 23 /* 24 * Information about time zone files. 25 */ 26 27 #define TZDEFAULT "/etc/localtime" 28 #define TZDEFRULES "posixrules" 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 39 struct tzhead 40 { 41 char tzh_magic[4]; /* TZ_MAGIC */ 42 char tzh_version[1]; /* '\0' or '2' or '3' as of 2013 */ 43 char tzh_reserved[15]; /* reserved; must be zero */ 44 char tzh_ttisutcnt[4]; /* coded number of trans. time flags */ 45 char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */ 46 char tzh_leapcnt[4]; /* coded number of leap seconds */ 47 char tzh_timecnt[4]; /* coded number of transition times */ 48 char tzh_typecnt[4]; /* coded number of local time types */ 49 char tzh_charcnt[4]; /* coded number of abbr. chars */ 50 }; 51 52 /* 53 * . . .followed by. . . 54 * 55 * tzh_timecnt (char [4])s coded transition times a la time(2) 56 * tzh_timecnt (unsigned char)s types of local time starting at above 57 * tzh_typecnt repetitions of 58 * one (char [4]) coded UT offset in seconds 59 * one (unsigned char) used to set tm_isdst 60 * one (unsigned char) that's an abbreviation list index 61 * tzh_charcnt (char)s '\0'-terminated zone abbreviations 62 * tzh_leapcnt repetitions of 63 * one (char [4]) coded leap second transition times 64 * one (char [4]) total correction after above 65 * tzh_ttisstdcnt (char)s indexed by type; if 1, transition 66 * time is standard time, if 0, 67 * transition time is local (wall clock) 68 * time; if absent, transition times are 69 * assumed to be local time 70 * tzh_ttisutcnt (char)s indexed by type; if 1, transition 71 * time is UT, if 0, transition time is 72 * local time; if absent, transition 73 * times are assumed to be local time. 74 * When this is 1, the corresponding 75 * std/wall indicator must also be 1. 76 */ 77 78 /* 79 * If tzh_version is '2' or greater, the above is followed by a second instance 80 * of tzhead and a second instance of the data in which each coded transition 81 * time uses 8 rather than 4 chars, 82 * then a POSIX-TZ-environment-variable-style string for use in handling 83 * instants after the last transition time stored in the file 84 * (with nothing between the newlines if there is no POSIX representation for 85 * such instants). 86 * 87 * If tz_version is '3' or greater, the above is extended as follows. 88 * First, the POSIX TZ string's hour offset may range from -167 89 * through 167 as compared to the POSIX-required 0 through 24. 90 * Second, its DST start time may be January 1 at 00:00 and its stop 91 * time December 31 at 24:00 plus the difference between DST and 92 * standard time, indicating DST all year. 93 */ 94 95 /* 96 * In the current implementation, "tzset()" refuses to deal with files that 97 * exceed any of the limits below. 98 */ 99 100 #define TZ_MAX_TIMES 2000 101 102 /* This must be at least 17 for Europe/Samara and Europe/Vilnius. */ 103 #define TZ_MAX_TYPES 256 /* Limited by what (unsigned char)'s can hold */ 104 105 #define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */ 106 /* (limited by what unsigned chars can hold) */ 107 108 #define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */ 109 110 #endif /* !defined TZFILE_H */ 111