svn commit: r347606 - head/usr.sbin/ntp/ntpd
Xin LI
delphij at FreeBSD.org
Wed May 15 03:39:28 UTC 2019
Author: delphij
Date: Wed May 15 03:39:27 2019
New Revision: 347606
URL: https://svnweb.freebsd.org/changeset/base/347606
Log:
Replace the leap-seconds file in r347488 from USNO with a
leap-seconds file from NIST at ftp://ftp.nist.gov/pub/time.
Future updates should use the NIST version of file, available
at ftp://ftp.nist.gov/pub/time/leap-seconds.list .
Requested by: ian@
Obtained from: ftp://ftp.nist.gov/pub/time/leap-seconds.3676924800
MFC after: 3 days
Modified:
head/usr.sbin/ntp/ntpd/leap-seconds
Modified: head/usr.sbin/ntp/ntpd/leap-seconds
==============================================================================
--- head/usr.sbin/ntp/ntpd/leap-seconds Wed May 15 01:40:40 2019 (r347605)
+++ head/usr.sbin/ntp/ntpd/leap-seconds Wed May 15 03:39:27 2019 (r347606)
@@ -1,10 +1,10 @@
#
# In the following text, the symbol '#' introduces
-# a comment, which continues from that symbol until
+# a comment, which continues from that symbol until
# the end of the line. A plain comment line has a
# whitespace character following the comment indicator.
-# There are also special comment lines defined below.
-# A special comment will always have a non-whitespace
+# There are also special comment lines defined below.
+# A special comment will always have a non-whitespace
# character in column 2.
#
# A blank line should be ignored.
@@ -15,17 +15,22 @@
# are transmitted by almost all time services.
#
# The first column shows an epoch as a number of seconds
-# since 1900.0 and the second column shows the number of
-# seconds that must be added to UTC to compute TAI for
-# any timestamp at or after that epoch. The value on
-# each line is valid from the indicated initial instant
-# until the epoch given on the next one or indefinitely
-# into the future if there is no next line.
+# since 1 January 1900, 00:00:00 (1900.0 is also used to
+# indicate the same epoch.) Both of these time stamp formats
+# ignore the complexities of the time scales that were
+# used before the current definition of UTC at the start
+# of 1972. (See note 3 below.)
+# The second column shows the number of seconds that
+# must be added to UTC to compute TAI for any timestamp
+# at or after that epoch. The value on each line is
+# valid from the indicated initial instant until the
+# epoch given on the next one or indefinitely into the
+# future if there is no next line.
# (The comment on each line shows the representation of
-# the corresponding initial epoch in the usual
+# the corresponding initial epoch in the usual
# day-month-year format. The epoch always begins at
# 00:00:00 UTC on the indicated day. See Note 5 below.)
-#
+#
# Important notes:
#
# 1. Coordinated Universal Time (UTC) is often referred to
@@ -33,7 +38,7 @@
# longer used, and the use of GMT to designate UTC is
# discouraged.
#
-# 2. The UTC time scale is realized by many national
+# 2. The UTC time scale is realized by many national
# laboratories and timing centers. Each laboratory
# identifies its realization with its name: Thus
# UTC(NIST), UTC(USNO), etc. The differences among
@@ -42,12 +47,12 @@
# and can be ignored for many purposes. These differences
# are tabulated in Circular T, which is published monthly
# by the International Bureau of Weights and Measures
-# (BIPM). See www.bipm.fr for more information.
+# (BIPM). See www.bipm.org for more information.
#
-# 3. The current defintion of the relationship between UTC
-# and TAI dates from 1 January 1972. A number of different
-# time scales were in use before than epoch, and it can be
-# quite difficult to compute precise timestamps and time
+# 3. The current definition of the relationship between UTC
+# and TAI dates from 1 January 1972. A number of different
+# time scales were in use before that epoch, and it can be
+# quite difficult to compute precise timestamps and time
# intervals in those "prehistoric" days. For more information,
# consult:
#
@@ -56,38 +61,41 @@
# or
# Terry Quinn, "The BIPM and the Accurate Measurement
# of Time," Proc. of the IEEE, Vol. 79, pp. 894-905,
-# July, 1991.
+# July, 1991. <http://dx.doi.org/10.1109/5.84965>
+# reprinted in:
+# Christine Hackman and Donald B Sullivan (eds.)
+# Time and Frequency Measurement
+# American Association of Physics Teachers (1996)
+# <http://tf.nist.gov/general/pdf/1168.pdf>, pp. 75-86
#
-# 4. The insertion of leap seconds into UTC is currently the
-# responsibility of the International Earth Rotation Service,
-# which is located at the Paris Observatory:
+# 4. The decision to insert a leap second into UTC is currently
+# the responsibility of the International Earth Rotation and
+# Reference Systems Service. (The name was changed from the
+# International Earth Rotation Service, but the acronym IERS
+# is still used.)
#
-# Central Bureau of IERS
-# 61, Avenue de l'Observatoire
-# 75014 Paris, France.
+# Leap seconds are announced by the IERS in its Bulletin C.
#
-# Leap seconds are announced by the IERS in its Bulletin C
+# See www.iers.org for more details.
#
-# See hpiers.obspm.fr or www.iers.org for more details.
+# Every national laboratory and timing center uses the
+# data from the BIPM and the IERS to construct UTC(lab),
+# their local realization of UTC.
#
-# All national laboratories and timing centers use the
-# data from the BIPM and the IERS to construct their
-# local realizations of UTC.
-#
# Although the definition also includes the possibility
-# of dropping seconds ("negative" leap seconds), this has
-# never been done and is unlikely to be necessary in the
+# of dropping seconds ("negative" leap seconds), this has
+# never been done and is unlikely to be necessary in the
# foreseeable future.
#
# 5. If your system keeps time as the number of seconds since
# some epoch (e.g., NTP timestamps), then the algorithm for
# assigning a UTC time stamp to an event that happens during a positive
-# leap second is not well defined. The official name of that leap
-# second is 23:59:60, but there is no way of representing that time
-# in these systems.
-# Many systems of this type effectively stop the system clock for
-# one second during the leap second and use a time that is equivalent
-# to 23:59:59 UTC twice. For these systems, the corresponding TAI
+# leap second is not well defined. The official name of that leap
+# second is 23:59:60, but there is no way of representing that time
+# in these systems.
+# Many systems of this type effectively stop the system clock for
+# one second during the leap second and use a time that is equivalent
+# to 23:59:59 UTC twice. For these systems, the corresponding TAI
# timestamp would be obtained by advancing to the next entry in the
# following table when the time equivalent to 23:59:59 UTC
# is used for the second time. Thus the leap second which
@@ -102,7 +110,7 @@
#
# If your system realizes the leap second by repeating 00:00:00 UTC twice
# (this is possible but not usual), then the advance to the next entry
-# in the table must occur the second time that a time equivlent to
+# in the table must occur the second time that a time equivalent to
# 00:00:00 UTC is used. Thus, using the same example as above:
#
# ...
@@ -112,66 +120,94 @@
# ...
#
# in both cases the use of timestamps based on TAI produces a smooth
-# time scale with no discontinuity in the time interval.
+# time scale with no discontinuity in the time interval. However,
+# although the long-term behavior of the time scale is correct in both
+# methods, the second method is technically not correct because it adds
+# the extra second to the wrong day.
#
-# This complexity would not be needed for negative leap seconds (if they
-# are ever used). The UTC time would skip 23:59:59 and advance from
-# 23:59:58 to 00:00:00 in that case. The TAI offset would decrease by
-# 1 second at the same instant. This is a much easier situation to deal
-# with, since the difficulty of unambiguously representing the epoch
+# This complexity would not be needed for negative leap seconds (if they
+# are ever used). The UTC time would skip 23:59:59 and advance from
+# 23:59:58 to 00:00:00 in that case. The TAI offset would decrease by
+# 1 second at the same instant. This is a much easier situation to deal
+# with, since the difficulty of unambiguously representing the epoch
# during the leap second does not arise.
#
+# Some systems implement leap seconds by amortizing the leap second
+# over the last few minutes of the day. The frequency of the local
+# clock is decreased (or increased) to realize the positive (or
+# negative) leap second. This method removes the time step described
+# above. Although the long-term behavior of the time scale is correct
+# in this case, this method introduces an error during the adjustment
+# period both in time and in frequency with respect to the official
+# definition of UTC.
+#
# Questions or comments to:
-# Jeff Prillaman
-# Time Service Department
-# US Naval Observatory
-# Washington, DC
-# jeff.k.prillaman at navy.mil
+# Judah Levine
+# Time and Frequency Division
+# NIST
+# Boulder, Colorado
+# Judah.Levine at nist.gov
#
-# Last Update of leap second values: 28 Jan 2019
+# Last Update of leap second values: 8 July 2016
#
-# The following line shows this last update date in NTP timestamp
+# The following line shows this last update date in NTP timestamp
# format. This is the date on which the most recent change to
# the leap second data was added to the file. This line can
-# be identified by the unique pair of characters in the first two
+# be identified by the unique pair of characters in the first two
# columns as shown below.
#
-#$ 3757622400
+#$ 3676924800
#
-# The data in this file will be updated periodically as new leap
+# The NTP timestamps are in units of seconds since the NTP epoch,
+# which is 1 January 1900, 00:00:00. The Modified Julian Day number
+# corresponding to the NTP time stamp, X, can be computed as
+#
+# X/86400 + 15020
+#
+# where the first term converts seconds to days and the second
+# term adds the MJD corresponding to the time origin defined above.
+# The integer portion of the result is the integer MJD for that
+# day, and any remainder is the time of day, expressed as the
+# fraction of the day since 0 hours UTC. The conversion from day
+# fraction to seconds or to hours, minutes, and seconds may involve
+# rounding or truncation, depending on the method used in the
+# computation.
+#
+# The data in this file will be updated periodically as new leap
# seconds are announced. In addition to being entered on the line
-# above, the update time (in NTP format) will be added to the basic
+# above, the update time (in NTP format) will be added to the basic
# file name leap-seconds to form the name leap-seconds.<NTP TIME>.
-# In addition, the generic name leap-seconds.list will always point to
+# In addition, the generic name leap-seconds.list will always point to
# the most recent version of the file.
#
# This update procedure will be performed only when a new leap second
-# is announced.
+# is announced.
#
# The following entry specifies the expiration date of the data
-# in this file in units of seconds since 1900.0. This expiration date
-# will be changed at least twice per year whether or not a new leap
-# second is announced. These semi-annual changes will be made no
-# later than 1 June and 1 December of each year to indicate what
-# action (if any) is to be taken on 30 June and 31 December,
+# in this file in units of seconds since the origin at the instant
+# 1 January 1900, 00:00:00. This expiration date will be changed
+# at least twice per year whether or not a new leap second is
+# announced. These semi-annual changes will be made no later
+# than 1 June and 1 December of each year to indicate what
+# action (if any) is to be taken on 30 June and 31 December,
# respectively. (These are the customary effective dates for new
# leap seconds.) This expiration date will be identified by a
# unique pair of characters in columns 1 and 2 as shown below.
-# In the unlikely event that a leap second is announced with an
+# In the unlikely event that a leap second is announced with an
# effective date other than 30 June or 31 December, then this
# file will be edited to include that leap second as soon as it is
# announced or at least one month before the effective date
-# (whichever is later).
-# If an announcement by the IERS specifies that no leap second is
-# scheduled, then only the expiration date of the file will
+# (whichever is later).
+# If an announcement by the IERS specifies that no leap second is
+# scheduled, then only the expiration date of the file will
# be advanced to show that the information in the file is still
-# current -- the update time stamp, the data and the name of the file
+# current -- the update time stamp, the data and the name of the file
# will not change.
#
-# Updated through IERS Bulletin C 57
-# File expires on: 1 Dec 2019
+# Updated through IERS Bulletin C57
+# File expires on: 28 December 2019
#
-#@ 3784147200
+#@ 3786480000
#
2272060800 10 # 1 Jan 1972
2287785600 11 # 1 Jul 1972
@@ -205,16 +241,15 @@
# the following special comment contains the
# hash value of the data in this file computed
# use the secure hash algorithm as specified
-# by FIPS 180-1. See the files in ~/sha for
+# by FIPS 180-1. See the files in ~/pub/sha for
# the details of how this hash value is
# computed. Note that the hash computation
# ignores comments and whitespace characters
# in data lines. It includes the NTP values
-# of both the last modification time and the
+# of both the last modification time and the
# expiration time of the file, but not the
# white space on those lines.
# the hash line is also ignored in the
# computation.
#
-#h 630ac741 2fffdd6b 858a7d1d 31d4802f 6382e10c
-#
+#h 83c68138 d3650221 07dbbbcd 11fcc859 ced1106a
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