[tz] [PATCH 1/5] Move a few links to ‘backward’
Paul Eggert
eggert at cs.ucla.edu
Mon Sep 26 00:32:17 UTC 2022
If a Link is just an alternate name, it’s not needed for zone.tab
and ‘backward’ is a better home for it anyway. This helps improve
link checking.
* Makefile (check_links): Use new backcheck option.
* asia (Europe/Nicosia):
* etcetera (Etc/Universal, Etc/Zulu, Etc/Greenwich, Etc/GMT-0)
(Etc/GMT+0, Etc/GMT0):
* europe (Asia/Istanbul):
Move Link to ‘backward’.
* checklinks.awk: Add backcheck option, to check that
non-‘backward’ Links are next to the Zones they link to, and that
a Link is in a continental file if and only if it is in zone.tab.
Add a special case for GMT.
* etcetera (GMT): In vanguard form, now a Zone, not a Link,
since it’s the file the leap second code depends on.
(Etc/GMT): In vanguard form, now a link in ‘backward’ instead of a
Zone here.
* ziguard.awk: Support the vanguard form.
---
Makefile | 3 ++-
NEWS | 17 +++++++++++++++++
asia | 4 ----
backward | 26 ++++++++++++++++++++++++++
checklinks.awk | 27 +++++++++++++++++++++++++++
etcetera | 17 +++++++----------
europe | 1 -
theory.html | 1 +
zdump.c | 4 ++--
ziguard.awk | 14 ++++++++++++++
10 files changed, 96 insertions(+), 18 deletions(-)
diff --git a/Makefile b/Makefile
index b68f843..69cb704 100644
--- a/Makefile
+++ b/Makefile
@@ -823,7 +823,8 @@ check_sorted: backward backzone iso3166.tab zone.tab zone1970.tab
touch $@
check_links: checklinks.awk $(TDATA_TO_CHECK) tzdata.zi
- $(AWK) -f checklinks.awk $(TDATA_TO_CHECK)
+ $(AWK) -f checklinks.awk -v backcheck=backward \
+ $(TDATA_TO_CHECK)
$(AWK) -f checklinks.awk tzdata.zi
touch $@
diff --git a/NEWS b/NEWS
index 64327d0..1e22ef7 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,22 @@
News for the tz database
+Unreleased, experimental changes
+
+ Briefly:
+ Move links to 'backward'.
+ In vanguard form, GMT is now a Zone and Etc/GMT a link.
+
+ Changes to data
+
+ Move links to 'backward' to ease and simplify link maintenance.
+ This affects generated data only if you use 'make BACKWARD='.
+
+ GMT is now a Zone and Etc/GMT a link instead of vice versa,
+ as GMT is needed for leap second support whereas Etc/GMT is not.
+ However, this change exposes a bug in TZUpdater 2.3.2 so it is
+ present only in vanguard form for now.
+
+
Release 2022d - 2022-09-23 12:02:57 -0700
Briefly:
diff --git a/asia b/asia
index e0daae0..5a33a8e 100644
--- a/asia
+++ b/asia
@@ -1172,10 +1172,6 @@ Zone Asia/Famagusta 2:15:48 - LMT 1921 Nov 14
3:00 - +03 2017 Oct 29 1:00u
2:00 EUAsia EE%sT
-# Classically, Cyprus belongs to Asia; e.g. see Herodotus, Histories, I.72.
-# However, for various reasons many users expect to find it under Europe.
-Link Asia/Nicosia Europe/Nicosia
-
# Georgia
# From Paul Eggert (1994-11-19):
# Today's _Economist_ (p 60) reports that Georgia moved its clocks forward
diff --git a/backward b/backward
index 14e4b14..517ec89 100644
--- a/backward
+++ b/backward
@@ -43,6 +43,8 @@ Link Asia/Shanghai Asia/Chongqing
Link Asia/Shanghai Asia/Chungking
Link Asia/Dhaka Asia/Dacca
Link Asia/Shanghai Asia/Harbin
+# Istanbul is in both continents.
+Link Europe/Istanbul Asia/Istanbul
Link Asia/Urumqi Asia/Kashgar
Link Asia/Kathmandu Asia/Katmandu
Link Asia/Macau Asia/Macao
@@ -86,18 +88,42 @@ Link Pacific/Easter Chile/EasterIsland
Link America/Havana Cuba
Link Africa/Cairo Egypt
Link Europe/Dublin Eire
+# Vanguard section, for most .zi parsers.
+#Link GMT Etc/GMT
+#Link GMT Etc/GMT+0
+#Link GMT Etc/GMT-0
+#Link GMT Etc/GMT0
+#Link GMT Etc/Greenwich
+# Rearguard section, for TZUpdater 2.3.2 and earlier.
+Link Etc/GMT Etc/GMT+0
+Link Etc/GMT Etc/GMT-0
+Link Etc/GMT Etc/GMT0
+Link Etc/GMT Etc/Greenwich
+# End of rearguard section.
Link Etc/UTC Etc/UCT
+Link Etc/UTC Etc/Universal
+Link Etc/UTC Etc/Zulu
Link Europe/London Europe/Belfast
Link Europe/Kyiv Europe/Kiev
+# Classically, Cyprus is in Asia; e.g. see Herodotus, Histories, I.72.
+# However, for various reasons many users expect to find it under Europe.
+Link Asia/Nicosia Europe/Nicosia
Link Europe/Chisinau Europe/Tiraspol
Link Europe/Kyiv Europe/Uzhgorod
Link Europe/Kyiv Europe/Zaporozhye
Link Europe/London GB
Link Europe/London GB-Eire
+# Vanguard section, for most .zi parsers.
+#Link GMT GMT+0
+#Link GMT GMT-0
+#Link GMT GMT0
+#Link GMT Greenwich
+# Rearguard section, for TZUpdater 2.3.2 and earlier.
Link Etc/GMT GMT+0
Link Etc/GMT GMT-0
Link Etc/GMT GMT0
Link Etc/GMT Greenwich
+# End of rearguard section.
Link Asia/Hong_Kong Hongkong
Link Africa/Abidjan Iceland
Link Asia/Tehran Iran
diff --git a/checklinks.awk b/checklinks.awk
index f309010..45f67e3 100644
--- a/checklinks.awk
+++ b/checklinks.awk
@@ -7,6 +7,18 @@ BEGIN {
# It is a newline so that it cannot match a valid name.
# It is not null so that its slot does not appear unset.
Zone = "\n"
+
+ if (!zone_table) zone_table = "zone.tab"
+
+ while (getline <zone_table) {
+ if (/^#/) continue
+ zone_cc[$3] = $1
+ }
+
+ # As a special case, a link to "GMT" is allowed in a continental file.
+ # Remove this special case once the hack for TZUpdater 2.3.2 is
+ # moved from main to reaguard form.
+ zone_cc["GMT"] = 1
}
/^Z/ {
@@ -19,6 +31,7 @@ BEGIN {
status = 1
}
defined[$2] = Zone
+ last_zone = $2
}
/^L/ {
@@ -32,6 +45,20 @@ BEGIN {
}
status = 1
}
+ if (backcheck) {
+ backward = FILENAME == backcheck
+ if (!!zone_cc[$3] == backward) {
+ shouldbe = backward ? "a continental file" : "'backward'"
+ printf "%s:%d: %s: Link should be in %s\n", \
+ FILENAME, FNR, $3, shouldbe
+ status = 1
+ }
+ if (!backward && $2 != last_zone) {
+ printf "%s:%d: Link %s should come just after Zone %s\n", \
+ FILENAME, FNR, $3, $2
+ status = 1
+ }
+ }
used[$2] = 1
defined[$3] = $2
}
diff --git a/etcetera b/etcetera
index a7e0eb4..865a220 100644
--- a/etcetera
+++ b/etcetera
@@ -16,26 +16,23 @@
# Do not use a POSIX TZ setting like TZ='GMT+4', which is four hours
# behind GMT but uses the completely misleading abbreviation "GMT".
-Zone Etc/GMT 0 - GMT
-
# The following zone is used by tzcode functions like gmtime,
# which load the "UTC" file to handle seconds properly.
Zone Etc/UTC 0 - UTC
+# Functions like gmtime load the "GMT" file to handle leap seconds properly.
+# Vanguard section, which works with most .zi parsers.
+#Zone GMT 0 - GMT
+# Rearguard section, for TZUpdater 2.3.2 and earlier.
+Zone Etc/GMT 0 - GMT
+
# The following link uses older naming conventions,
# but it belongs here, not in the file 'backward',
# as it is needed for tzcode releases through 2022a,
# where functions like gmtime load "GMT" instead of the "Etc/UTC".
# We want this to work even on installations that omit 'backward'.
Link Etc/GMT GMT
-
-Link Etc/UTC Etc/Universal
-Link Etc/UTC Etc/Zulu
-
-Link Etc/GMT Etc/Greenwich
-Link Etc/GMT Etc/GMT-0
-Link Etc/GMT Etc/GMT+0
-Link Etc/GMT Etc/GMT0
+# End of rearguard section.
# Be consistent with POSIX TZ settings in the Zone names,
# even though this is the opposite of what many people expect.
diff --git a/europe b/europe
index bb0c7cf..76b741b 100644
--- a/europe
+++ b/europe
@@ -3734,7 +3734,6 @@ Zone Europe/Istanbul 1:55:52 - LMT 1880
2:00 1:00 EEST 2015 Nov 8 1:00u
2:00 EU EE%sT 2016 Sep 7
3:00 - +03
-Link Europe/Istanbul Asia/Istanbul # Istanbul is in both continents.
# Ukraine
#
diff --git a/theory.html b/theory.html
index 56390ae..298db86 100644
--- a/theory.html
+++ b/theory.html
@@ -329,6 +329,7 @@ still supported.
These legacy names are mostly defined in the file
'<code>etcetera</code>'.
Also, the file '<code>backward</code>' defines the legacy names
+'<code>Etc/GMT0</code>', '<code>Etc/GMT-0</code>', '<code>Etc/GMT+0</code>',
'<code>GMT0</code>', '<code>GMT-0</code>' and '<code>GMT+0</code>',
and the file '<code>northamerica</code>' defines the legacy names
'<code>EST5EDT</code>', '<code>CST6CDT</code>',
diff --git a/zdump.c b/zdump.c
index a63a343..ef6cb8b 100644
--- a/zdump.c
+++ b/zdump.c
@@ -281,9 +281,9 @@ gmtzinit(void)
if (USE_LOCALTIME_RZ) {
/* Try "GMT" first to find out whether this is one of the rare
platforms where time_t counts leap seconds; this works due to
- the "Link Etc/GMT GMT" line in the "etcetera" file. If "GMT"
+ the "Zone GMT 0 - GMT" line in the "etcetera" file. If "GMT"
fails, fall back on "GMT0" which might be similar due to the
- "Link Etc/GMT GMT0" line in the "backward" file, and which
+ "Link GMT GMT0" line in the "backward" file, and which
should work on all POSIX platforms. The rest of zdump does not
use the "GMT" abbreviation that comes from this setting, so it
is OK to use "GMT" here rather than the more-modern "UTC" which
diff --git a/ziguard.awk b/ziguard.awk
index 0556cc4..a864f9f 100644
--- a/ziguard.awk
+++ b/ziguard.awk
@@ -15,6 +15,9 @@
# after main became rearguard and vanguard became main).
# There is no need to convert rearguard to other forms.
#
+# When converting to vanguard form, the output can use the line
+# "Zone GMT 0 - GMT" which TZUpdater 2.3.2 mistakenly rejects.
+#
# When converting to vanguard form, the output can use negative SAVE
# values.
#
@@ -151,6 +154,17 @@ DATAFORM != "main" {
}
}
+ # In vanguard form, use the line "Zone GMT 0 - GMT" instead of
+ # "Zone Etc/GMT 0 - GMT" and adjust Link lines accordingly.
+ # This works around a bug in TZUpdater 2.3.2.
+ if (/^#?(Zone|Link)[\t ]+(Etc\/)?GMT[\t ]/) {
+ if (($2 == "GMT") == (DATAFORM == "vanguard")) {
+ uncomment = in_comment
+ } else {
+ comment_out = !in_comment
+ }
+ }
+
if (uncomment) {
sub(/^#/, "")
}
--
2.37.3
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