mirror of git://sourceware.org/git/glibc.git
122 lines
4.1 KiB
C
122 lines
4.1 KiB
C
/* Layout and location of TZif files. */
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#ifndef TZFILE_H
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#define TZFILE_H
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/*
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** This file is in the public domain, so clarified as of
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** 1996-06-05 by Arthur David Olson.
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*/
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/*
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** This header is for use ONLY with the time conversion code.
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** There is no guarantee that it will remain unchanged,
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** or that it will remain at all.
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** Do NOT copy it to any system include directory.
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** Thank you!
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*/
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/*
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** Information about time zone files.
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*/
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#ifndef TZDEFRULES
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# define TZDEFRULES "posixrules"
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#endif /* !defined TZDEFRULES */
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/* See Internet RFC 8536 for more details about the following format. */
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/*
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** Each file begins with. . .
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*/
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#define TZ_MAGIC "TZif"
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struct tzhead {
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char tzh_magic[4]; /* TZ_MAGIC */
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char tzh_version[1]; /* '\0' or '2'-'4' as of 2021 */
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char tzh_reserved[15]; /* reserved; must be zero */
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char tzh_ttisutcnt[4]; /* coded number of trans. time flags */
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char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */
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char tzh_leapcnt[4]; /* coded number of leap seconds */
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char tzh_timecnt[4]; /* coded number of transition times */
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char tzh_typecnt[4]; /* coded number of local time types */
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char tzh_charcnt[4]; /* coded number of abbr. chars */
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};
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/*
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** . . .followed by. . .
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**
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** tzh_timecnt (char [4])s coded transition times a la time(2)
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** tzh_timecnt (unsigned char)s types of local time starting at above
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** tzh_typecnt repetitions of
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** one (char [4]) coded UT offset in seconds
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** one (unsigned char) used to set tm_isdst
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** one (unsigned char) that's an abbreviation list index
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** tzh_charcnt (char)s '\0'-terminated zone abbreviations
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** tzh_leapcnt repetitions of
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** one (char [4]) coded leap second transition times
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** one (char [4]) total correction after above
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** tzh_ttisstdcnt (char)s indexed by type; if 1, transition
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** time is standard time, if 0,
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** transition time is local (wall clock)
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** time; if absent, transition times are
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** assumed to be local time
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** tzh_ttisutcnt (char)s indexed by type; if 1, transition
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** time is UT, if 0, transition time is
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** local time; if absent, transition
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** times are assumed to be local time.
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** When this is 1, the corresponding
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** std/wall indicator must also be 1.
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*/
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/*
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** If tzh_version is '2' or greater, the above is followed by a second instance
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** of tzhead and a second instance of the data in which each coded transition
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** time uses 8 rather than 4 chars,
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** then a POSIX.1-2017 proleptic TZ string for use in handling
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** instants after the last transition time stored in the file
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** (with nothing between the newlines if there is no POSIX.1-2017
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** representation for such instants).
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**
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** If tz_version is '3' or greater, the TZ string can be any POSIX.1-2024
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** proleptic TZ string, which means the above is extended as follows.
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** First, the TZ string's hour offset may range from -167
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** through 167 as compared to the range 0 through 24 required
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** by POSIX.1-2017 and earlier.
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** Second, its DST start time may be January 1 at 00:00 and its stop
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** time December 31 at 24:00 plus the difference between DST and
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** standard time, indicating DST all year.
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*/
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/*
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** In the current implementation, "tzset()" refuses to deal with files that
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** exceed any of the limits below.
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*/
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#ifndef TZ_MAX_TIMES
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/* This must be at least 242 for Europe/London with 'zic -b fat'. */
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# define TZ_MAX_TIMES 2000
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#endif /* !defined TZ_MAX_TIMES */
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#ifndef TZ_MAX_TYPES
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/* This must be at least 18 for Europe/Vilnius with 'zic -b fat'. */
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# define TZ_MAX_TYPES 256 /* Limited by what (unsigned char)'s can hold */
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#endif /* !defined TZ_MAX_TYPES */
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#ifndef TZ_MAX_CHARS
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/* This must be at least 40 for America/Anchorage. */
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# define TZ_MAX_CHARS 50 /* Maximum number of abbreviation characters */
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/* (limited by what unsigned chars can hold) */
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#endif /* !defined TZ_MAX_CHARS */
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#ifndef TZ_MAX_LEAPS
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/* This must be at least 27 for leap seconds from 1972 through mid-2023.
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There's a plan to discontinue leap seconds by 2035. */
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# define TZ_MAX_LEAPS 50 /* Maximum number of leap second corrections */
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#endif /* !defined TZ_MAX_LEAPS */
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#endif /* !defined TZFILE_H */
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