tzfile.h

/* 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 TZDIR
#define TZDIR   "/usr/share/zoneinfo" /* Time zone object file directory */
#endif /* !defined TZDIR */
 
#ifndef TZDEFAULT
#define TZDEFAULT   "/etc/localtime"
#endif /* !defined TZDEFAULT */
 
#ifndef TZDEFRULES
#define TZDEFRULES  "posixrules"
#endif /* !defined TZDEFRULES */
 
 
/* See Internet RFC 8536 *shfor more details about the following format.  */
 
/*
** Each file begins with. . .
*/
 
#define TZ_MAGIC    "TZif"
 
struct tzhead {
    char    tzh_magic[4];       /* TZ_MAGIC */
    char    tzh_version[1];     /* '\0' or '2' or '3' as of 2013 */
    char    tzh_reserved[15];   /* reserved; must be zero */
    char    tzh_ttisutcnt[4];   /* coded number of trans. time flags */
    char    tzh_ttisstdcnt[4];  /* coded number of trans. time flags */
    char    tzh_leapcnt[4];     /* coded number of leap seconds */
    char    tzh_timecnt[4];     /* coded number of transition times */
    char    tzh_typecnt[4];     /* coded number of local time types */
    char    tzh_charcnt[4];     /* coded number of abbr. chars */
};
 
/*
** . . .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 representation for
** such instants).
**
** If tz_version is '3' or greater, the above is extended as follows.
** First, the POSIX 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
#define TZ_MAX_TIMES    2000
#endif /* !defined TZ_MAX_TIMES */
 
#ifndef TZ_MAX_TYPES
/* This must be at least 17 for Europe/Samara and Europe/Vilnius.  */
#define TZ_MAX_TYPES    256 /* Limited by what (unsigned char)'s can hold */
#endif /* !defined TZ_MAX_TYPES */
 
#ifndef TZ_MAX_CHARS
#define TZ_MAX_CHARS    50  /* Maximum number of abbreviation characters */
                /* (limited by what unsigned chars can hold) */
#endif /* !defined TZ_MAX_CHARS */
 
#ifndef TZ_MAX_LEAPS
#define TZ_MAX_LEAPS    50  /* Maximum number of leap second corrections */
#endif /* !defined TZ_MAX_LEAPS */
 
#endif /* !defined TZFILE_H */