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