Index for Section 4

Alphabetical listing for T

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tzfile(4)
NAME
  tzfile - Time zone information

SYNOPSIS
  #include <tzfile.h>

DESCRIPTION
  The time zone information files used by tzset(3) begin with bytes reserved
  for future use, followed by six four-byte values, written in a standard
  byte order (that is, with the high-order byte of the value written first).
  These values are, in order:

  tzh_ttisgmtcnt
      The number of GMT/local indicators stored in the file.

  tzh_ttisstdcnt
      The number of standard/wall indicators stored in the file.

  tzh_leapcnt
      The number of leap seconds for which data is stored in the file.

  tzh_timecnt
      The number of transition times for which data is stored in the file.

  tzh_typecnt
      The number of local time types for which data is stored in the file.
      (This value must not be zero.)

  tzh_charcnt
      The number of characters of time zone abbreviation strings stored in
      the file.

  The above header is followed by tzh_timecnt four-byte values, sorted in
  ascending order.  These values are written in standard byte order.  Each is
  used as a transition time (as returned by time(3)) at which the rules for
  computing local time change.	Next come tzh_timecnt one-byte values of type
  unsigned char.  Each value tells which of the different local time types
  described in the file is associated with the same-indexed transition time.
  These values serve as indices into an array of ttinfo structures that
  appears next in the file.  These structures are defined as follows:

       struct ttinfo {
	long	      tt_gmtoff;
	int	      tt_isdst;
	unsigned int  tt_abbrind;
       };

  Each structure is written as a four-byte value for tt_gmtoff of type long,
  in a standard byte order, followed by a one-byte value for tt_isdst and a
  one-byte value for tt_abbrind.  In each structure, tt_gmtoff gives the
  number of seconds to be added to GMT, tt_isdst tells whether tm_isdst
  should be set by localtime(3) and tt_abbrind serves as an index into the
  array of time zone abbreviation characters that follow the ttinfo
  structure(s) in the file.

  Next, there are tzh_leapcnt pairs of four-byte values, written in standard
  byte order.  The first value of each pair gives the time (as returned by
  time(3)) at which a leap second occurs.  The second gives the total number
  of leap seconds to be applied after the given time.  The pairs of values
  are sorted in ascending order by time.

  Then there are tzh_ttisstdcnt standard/wall indicators, each stored as a
  one-byte value.  They tell whether the transition times associated with
  local time types were specified as standard time or wall clock time, and
  are used when a time zone file is used in handling POSIX-style time zone
  environment variables.

  Fnally, there are tzh_ttisgmtcnt GMT/local indicators, each stored as a
  one-byte value; they tell whether the transition times associated with
  local time types were specified as GMT or local time, and are used when a
  time zone file is used in handling POSIX-style time zone environment
  variables.

  The localtime(3) call uses the first standard-time ttinfo structure in the
  file (or simply the first ttinfo structure, in the absence of a standard-
  time structure) if either tzh_timecnt is zero or the time argument is less
  than the first transition time recorded in the file.

RELATED INFORMATION
  ctime(3)

Index for Section 4

Alphabetical listing for T

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