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