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
39struct 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