There's no functional change at all here, but I'm curious to see
whether this change successfully shuts up Coverity's warning about
a useless strcmp(), which appeared with the previous update.
Discussion: http://mm.icann.org/pipermail/tz/2020-October/029370.html
This changes zic's default output format from "-b fat" to "-b slim".
We were already using "slim" in v13/HEAD, so those branches drop
the explicit -b switch in the Makefiles. Instead, add an explicit
"-b fat" in v12 and before, so that we don't change the output file
format in those branches. (This is perhaps excessively conservative,
but we decided not to do so in a12079109, and I'll stick with that.)
Other non-cosmetic changes are to drop support for zic's long-obsolete
"-y" switch, and to ensure that strftime() does not change errno
unless it fails.
As usual with tzcode changes, back-patch to all supported branches.
The IANA tzcode library has a feature to read a time zone file named
"posixrules" and apply the daylight-savings transition dates and times
therein, when it is given a POSIX-style time zone specification that
lacks an explicit transition rule. However, there's a problem with
that code: it doesn't work for dates past the Y2038 time_t rollover.
(Effectively, all times beyond that point are treated as standard
time.) The IANA crew regard this feature as legacy, so their plan is
to remove it not fix it. The time frame in which that will happen
is unclear, but presumably it'll happen well before 2038.
Moreover, effective with the next IANA data update (probably this
fall), the recommended default will be to not install a "posixrules"
file in the first place. The time frame in which tzdata packagers
might adopt that suggestion is likewise unclear, but at least some
platforms will probably do it in the next year or so. While we could
ignore that recommendation so far as PG-supplied tzdata trees are
concerned, builds using --with-system-tzdata will be subject to
whatever the platform's tzdata packager decides to do.
Thus, whether or not we do anything, some increasing fraction of
Postgres users will be exposed to the behavior observed when there
is no "posixrules" file; and if we do nothing, we'll have essentially
no control over the timing of that change.
The best thing to do to ameliorate the uncertainty seems to be to
proactively remove the posixrules-reading feature. If we do that in
a scheduled release then at least we can release-note the behavioral
change, rather than having users be surprised by it after a routine
tzdata update.
The change in question is fairly minor anyway: to be affected,
you have to be using a POSIX-style timezone spec, it has to not
have an explicit rule, and it has to not be one of the four traditional
continental-USA zone names (EST5EDT, CST6CDT, MST7MDT, or PST8PDT),
as those are special-cased. Since the default "posixrules" file
provides USA DST rules, the number of people who are likely to find
such a zone spec useful is probably quite small. Moreover, the
fallback behavior with no explicit rule and no "posixrules" file is to
apply current USA rules, so the only thing that really breaks is the
DST transitions in years before 2007 (and you get the countervailing
fix that transitions after 2038 will be applied).
Now, some installations might have replaced the "posixrules" file,
allowing e.g. EU rules to be applied to a POSIX-style timezone spec.
That won't work anymore. But it's not exactly clear why this solution
would be preferable to using a regular named zone. In any case, given
the Y2038 issue, we need to be pushing users to stop depending on this.
Back-patch into v13; it hasn't been released yet, so it seems OK to
change its behavior. (Personally I think we ought to back-patch
further, but I've been outvoted.)
Discussion: https://postgr.es/m/1390.1562258309@sss.pgh.pa.us
Discussion: https://postgr.es/m/20200621211855.6211-1-eggert@cs.ucla.edu
This absorbs a leap-second-related bug fix in localtime.c, and
teaches zic to handle an expiration marker in the leapseconds file.
Neither are of any interest to us (for the foreseeable future
anyway), but we need to stay more or less in sync with upstream.
Also adjust some over-eager changes in the README from commit 957338418.
I have no intention of making changes that require C99 in this code,
until such time as all the live back branches require C99. Otherwise
back-patching will get too exciting.
For the same reason, absorb assorted whitespace and other cosmetic
changes from HEAD into the back branches; mostly this reflects use of
improved versions of pgindent.
All in all then, quite a boring update. But I figured I'd get it
done while I was looking at this code.
stdint.h belongs to the compiler (as opposed to inttypes.h), so by
requiring a C99 compiler we can also require stdint.h
unconditionally. Remove configure checks and other workarounds for
it.
This also removes a few steps in the required portability adjustments
to the imported time zone code, which can be applied on the next
import.
When using GCC on a platform that is otherwise pre-C99, this will now
require at least GCC 4.5, which is the first release that supplied a
standard-conforming stdint.h if the native platform didn't have it.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/5d398bbb-262a-5fed-d839-d0e5cff3c0d7%402ndquadrant.com
A large fraction of this diff is just due to upstream's somewhat
random decision to rename a bunch of internal variables and struct
fields. However, there is an interesting new feature in zic:
it's grown a "-b slim" option that emits zone files without 32-bit
data and other backwards-compatibility hacks. We should consider
whether we wish to enable that.
This corrects a small bug in zic that caused it to output an incorrect
year-2440 transition in the Africa/Casablanca zone.
More interestingly, zic has grown a "-r" option that limits the range of
zone transitions that it will put into the output files. That might be
useful to people who don't like the weird GMT offsets that tzdb likes
to use for very old dates. It appears that for dates before the cutoff
time specified with -r, zic will use the zone's standard-time offset
as of the cutoff time. So for example one might do
make install ZIC_OPTIONS='-r @-1893456000'
to cause all dates before 1910-01-01 to be treated as though 1910
standard time prevailed indefinitely far back. (Don't blame me for
the unfriendly way of specifying the cutoff time --- it's seconds
since or before the Unix epoch. You can use extract(epoch ...)
to calculate it.)
As usual, back-patch to all supported branches.
This patch absorbs an upstream fix to "zic" for a recently-introduced
bug that made it output data that some 32-bit clients couldn't read.
Given the current source data, the bug only manifests in zones with
leap seconds, which we don't generate, so that there's no actual
change in our installed timezone data files from this. Still, in
case somebody uses our copy of "zic" to do something else, it seems
best to apply the fix promptly.
Also, update the README's notes about converting upstream code to
our conventions.
About half of this is purely cosmetic changes to reduce the diff between
our code and theirs, like inserting "const" markers where they have them.
The other half is tracking actual code changes in zic.c and localtime.c.
I don't think any of these represent near-term compatibility hazards, but
it seems best to stay up to date.
I also fixed longstanding bugs in our code for producing the
known_abbrevs.txt list, which by chance hadn't been exposed before,
but which resulted in some garbage output after applying the upstream
changes in zic.c. Notably, because upstream removed their old phony
transitions at the Big Bang, it's now necessary to cope with TZif files
containing no DST transition times at all.
In the IANA timezone code, tzparse() always tries to load the zone
file named by TZDEFRULES ("posixrules"). Previously, we'd hacked
that logic to skip the load in the "lastditch" code path, which we use
only to initialize the default "GMT" zone during GUC initialization.
That's critical for a couple of reasons: since we do not support leap
seconds, we *must not* allow "GMT" to have leap seconds, and since this
case runs before the GUC subsystem is fully alive, we'd really rather
not take the risk of pg_open_tzfile throwing any errors.
However, that still left the code reading TZDEFRULES on every other
call, something we'd noticed to the extent of having added code to cache
the result so it was only done once per process not a lot of times.
Andres Freund complained about the static data space used up for the
cache; but as long as the logic was like this, there was no point in
trying to get rid of that space.
We can improve matters by looking a bit more closely at what the IANA
code actually needs the TZDEFRULES data for. One thing it does is
that if "posixrules" is a leap-second-aware zone, the leap-second
behavior will be absorbed into every POSIX-style zone specification.
However, that's a behavior we'd really prefer to do without, since
for our purposes the end effect is to render every POSIX-style zone
name unsupported. Otherwise, the TZDEFRULES data is used only if
the POSIX zone name specifies DST but doesn't include a transition
date rule (e.g., "EST5EDT" rather than "EST5EDT,M3.2.0,M11.1.0").
That is a minority case for our purposes --- in particular, it
never happens when tzload() invokes tzparse() to interpret a
transition date rule string found in a tzdata zone file.
Hence, if we legislate that we're going to ignore leap-second data
from "posixrules", we can postpone the TZDEFRULES load into the path
where we actually need to substitute for a missing date rule string.
That means it will never happen at all in common scenarios, making it
reasonable to dynamically allocate the cache space when it does happen.
Even when the data is already loaded, this saves some cycles in the
common code path since we avoid a memcpy of 23KB or so. And, IMO at
least, this is a less ugly hack on the IANA logic than what we had
before, since it's not messing with the lastditch-vs-regular code paths.
Back-patch to all supported branches, not so much because this is a
critical change as that I want to keep all our copies of the IANA
timezone code in sync.
Discussion: https://postgr.es/m/20181015200754.7y7zfuzsoux2c4ya@alap3.anarazel.de
The non-cosmetic changes involve teaching the "zic" tzdata compiler about
negative DST. While I'm not currently intending that we start using
negative-DST data right away, it seems possible that somebody would try
to use our copy of zic with bleeding-edge IANA data. So we'd better be
out in front of this change code-wise, even though it doesn't matter for
the data file we're shipping.
Discussion: https://postgr.es/m/30996.1525445902@sss.pgh.pa.us
Traditionally IANA has distributed their timezone data in pure source
form, replete with extensive historical comments. As of release 2017c,
they've added a compact single-file format that omits comments and
abbreviates command keywords. This form is way shorter than the pure
source, even before considering its allegedly better compressibility.
Hence, let's distribute the data in that form rather than pure source.
I'm pushing this now, rather than at the next timezone database update,
so that it's easy to confirm that this data file produces compiled zic
output that's identical to what we were getting before.
Discussion: https://postgr.es/m/1915.1511210334@sss.pgh.pa.us
This is a trivial update containing only cosmetic changes. The point
is just to get back to being synced with an official release of tzcode,
rather than some ad-hoc point in their commit history, which is where
commit 47f849a3c left it.
tzparse() would attempt to load the "posixrules" timezone database file on
each call. That might seem like it would only be an issue when selecting a
POSIX-style zone name rather than a zone defined in the timezone database,
but it turns out that each zone definition file contains a POSIX-style zone
string and tzload() will call tzparse() to parse that. Thus, when scanning
the whole timezone file tree as we do in the pg_timezone_names view,
"posixrules" was read repetitively for each zone definition file. Fix
that by caching the file on first use within any given process. (We cache
other zone definitions for the life of the process, so there seems little
reason not to cache this one as well.) This probably won't help much in
processes that never run pg_timezone_names, but even one additional SET
of the timezone GUC would come out ahead.
An even worse problem for pg_timezone_names is that pg_open_tzfile()
has an inefficient way of identifying the canonical case of a zone name:
it basically re-descends the directory tree to the zone file. That's not
awful for an individual "SET timezone" operation, but it's pretty horrid
when we're inspecting every zone in the database. And it's pointless too
because we already know the canonical spelling, having just read it from
the filesystem. Fix by teaching pg_open_tzfile() to avoid the directory
search if it's not asked for the canonical name, and backfilling the
proper result in pg_tzenumerate_next().
In combination these changes seem to make the pg_timezone_names view
about 3x faster to read, for me. Since a scan of pg_timezone_names
has up to now been one of the slowest queries in the regression tests,
this should help some little bit for buildfarm cycle times.
Back-patch to all supported branches, not so much because it's likely
that users will care much about the view's performance as because
tracking changes in the upstream IANA timezone code is really painful
if we don't keep all the branches in sync.
Discussion: https://postgr.es/m/27962.1493671706@sss.pgh.pa.us
zic no longer mishandles some transitions in January 2038 when it
attempts to work around Qt bug 53071. This fixes a bug affecting
Pacific/Tongatapu that was introduced in zic 2016e. localtime.c
now contains a workaround, useful when loading a file generated by
a buggy zic.
There are assorted cosmetic changes as well, notably relocation
of a bunch of #defines.
This is a trivial update (consisting in fact only in the addition of
a comment). The point is just to get back to being synced with an
official release of tzcode, rather than some ad-hoc point in their
commit history, which is where commit 1f87181e1 left it.
After further reflection about the mess cleaned up in commit 39b691f25,
I decided the main bit of test coverage that was still missing was to
check that the non-default abbreviation-set files we supply are usable.
Add that.
Back-patch to supported branches, just because it seems like a good
idea to keep this all in sync.
We hadn't done this in about six years, which proves to have been a mistake
because there's been a lot of code churn upstream, making the merge rather
painful. But putting it off any further isn't going to lessen the pain,
and there are at least two incompatible changes that we need to absorb
before someone starts complaining that --with-system-tzdata doesn't work
at all on their platform, or we get blindsided by a tzdata release that
our out-of-date zic can't compile. Last week's "time zone abbreviation
differs from POSIX standard" mess was a wake-up call in that regard.
This is a sufficiently large patch that I'm afraid to back-patch it
immediately, though the foregoing considerations imply that we probably
should do so eventually. For the moment, just put it in HEAD so that
it can get some testing. Maybe we can wait till the end of the 9.6
beta cycle before deeming it okay.
Add an option to zic.c to dump out all non-obsolete timezone abbreviations
defined in the Olson database. Comparing this list to its previous state
will clue us in when something happens that we may need to account for in
the tznames/ time zone abbreviation lists. The README file's previous
exhortation to "just grep for differences" was completely useless advice,
in my now-considerable experience; but maybe this will be a bit more
useful. As a starting point I built the same list from the tzdata files
as they existed in 2006, which is committed here as known_abbrevs.txt.
Comparison indeed turned up quite a few changes we had neglected to account
for, which I will commit separately.
corner cases that come up in certain timezones (apparently, only those with
lots and lots of distinct TZ transition rules, as far as I can gather from
a quick scan of their archives). Per suggestion from Jeevan Chalke.
Back-patch to 8.4. Possibly we need to push this into earlier releases
as well, but I'm hesitant to update them to the 64-bit tzcode without
more thought and testing.
this adds support for 64-bit tzdata files, which is needed to support DST
calculations beyond 2038. Add a regression test case to give some minimal
confidence that that really works.
Heikki Linnakangas
configuration files that can be altered by a DBA. The australian_timezones
GUC setting disappears, replaced by a timezone_abbreviations setting (set this
to 'Australia' to get the effect of australian_timezones). The list of zone
names defined by default has undergone a bit of cleanup, too. Documentation
still needs some work --- in particular, should we fix Table B-4, or just get
rid of it? Joachim Wieland, with some editorializing by moi.
and should do now that we control our own destiny for timezone handling,
but this commit gets the bulk of the picayune diffs in place.
Magnus Hagander and Tom Lane.
Tom Lane
Peter Eisentraut
Bruce Momjian
Magnus Hagander