pg_xlog is often a symlink, typically to a different filesystem. Don't
get confused and comlain about by that, and just always pretend that it's a
normal directory, even if it's really a symlink.

Also add a test case for this.

Backpatch to 9.5.

Since commit 01f6bb4b, TestLib.pm has exported path to tmp_check directory,
so let's use that also for the pg_rewind test clusters etc.

Also, in master, the $tempdir_short variable has not been used since commit
13d856e1, which moved the initdb-running code to TestLib.pm.

Backpatch to 9.5.

Not sure why /tmp_check/ was omitted from this one, but even if it
isn't really needed right now, it's inconsistent not to include it.

Oversight in commit cb3384a0.
Back-patch to 9.1, like that commit.

It's against project policy to use elog() for user-facing errors, or to
omit an errcode() selection for errors that aren't supposed to be "can't
happen" cases.  Fix all the violations of this policy that result in
ERRCODE_INTERNAL_ERROR log entries during the standard regression tests,
as errors that can reliably be triggered from SQL surely should be
considered user-facing.

I also looked through all the files touched by this commit and fixed
other nearby problems of the same ilk.  I do not claim to have fixed
all violations of the policy, just the ones in these files.

In a few places I also changed existing ERRCODE choices that didn't
seem particularly appropriate; mainly replacing ERRCODE_SYNTAX_ERROR
by something more specific.

Back-patch to 9.5, but no further; changing ERRCODE assignments in
stable branches doesn't seem like a good idea.

The Msys DTK perl, which is required to run TAP tests under Msys as a
native perl won't recognize the correct virtual paths, has its osname
recorded in the Config module as 'msys' instead of 'MSWin32'. To avoid
having to repeat the test a variable is created that is true iff the
osname is either of these values, and is then used everywhere that
matters.

As in commit 0a52d378, avoid doing something that has undefined
results according to the C standard, even though in practice there does
not seem to be any problem with it.

This fixes two places in numeric.c that demonstrably could call memcpy()
with such arguments.  I looked through that file and didn't see any other
places with similar hazards; this is not to claim that there are not such
places in other files.

Per report from Piotr Stefaniak.  Back-patch to 9.5 which is where the
previous commit was added.  We're more or less setting a precedent that
we will not worry about this type of issue in pre-9.5 branches unless
someone demonstrates a problem in the field.

An EAN beginning with 979 (but not 9790 - those are ISMN's) are accepted
as ISBN numbers, but they cannot be represented in the old, 10-digit ISBN
format. They must be output in the new 13-digit ISBN-13 format. We printed
out an incorrect value for those.

Also add a regression test, to test this and some other basic functionality
of the module.

Patch by Fabien Coelho. This fixes bug #13442, reported by B.Z. Backpatch
to 9.1, where we started to recognize ISBN-13 numbers.

Commit c9b0cbe9 accidentally broke the
order of operations during postmaster shutdown: it resulted in removing
the per-socket lockfiles after, not before, postmaster.pid.  This creates
a race-condition hazard for a new postmaster that's started immediately
after observing that postmaster.pid has disappeared; if it sees the
socket lockfile still present, it will quite properly refuse to start.
This error appears to be the explanation for at least some of the
intermittent buildfarm failures we've seen in the pg_upgrade test.

Another problem, which has been there all along, is that the postmaster
has never bothered to close() its listen sockets, but has just allowed them
to close at process death.  This creates a different race condition for an
incoming postmaster: it might be unable to bind to the desired listen
address because the old postmaster is still incumbent.  This might explain
some odd failures we've seen in the past, too.  (Note: this is not related
to the fact that individual backends don't close their client communication
sockets.  That behavior is intentional and is not changed by this patch.)

Fix by adding an on_proc_exit function that closes the postmaster's ports
explicitly, and (in 9.3 and up) reshuffling the responsibility for where
to unlink the Unix socket files.  Lock file unlinking can stay where it
is, but teach it to unlink the lock files in reverse order of creation.

If a call to WaitForXLogInsertionsToFinish() returned a value in the middle
of a page, and another backend then started to insert a record to the same
page, and then you called WaitXLogInsertionsToFinish() again, the second
call might return a smaller value than the first call. The problem was in
GetXLogBuffer(), which always updated the insertingAt value to the
beginning of the requested page, not the actual requested location. Because
of that, the second call might return a xlog pointer to the beginning of
the page, while the first one returned a later position on the same page.
XLogFlush() performs two calls to WaitXLogInsertionsToFinish() in
succession, and holds WALWriteLock on the second call, which can deadlock
if the second call to WaitXLogInsertionsToFinish() blocks.

Reported by Spiros Ioannou. Backpatch to 9.4, where the more scalable
WALInsertLock mechanism, and this bug, was introduced.

LWLockAttemptLock pointlessly read the lock's state in every loop
iteration, even though pg_atomic_compare_exchange_u32() returns the old
value. Instead do that only once before the loop iteration.

Additionally there's no need to have the expected_state variable,
old_state mostly had the same value anyway.

Noticed-By: Heikki Linnakangas
Backpatch: 9.5, no reason to let the branches diverge at this point

The lwlock scalability work introduced two race conditions into the
lwlock variable support provided for xlog.c. First, and harmlessly on
most platforms, it set/read the variable without the spinlock in some
places. Secondly, due to the removal of the spinlock, it was possible
that a backend missed changes to the variable's state if it changed in
the wrong moment because checking the lock's state, the variable's state
and the queuing are not protected by a single spinlock acquisition
anymore.

To fix first move resetting the variable's from LWLockAcquireWithVar to
WALInsertLockRelease, via a new function LWLockReleaseClearVar. That
prevents issues around waiting for a variable's value to change when a
new locker has acquired the lock, but not yet set the value. Secondly
re-check that the variable hasn't changed after enqueing, that prevents
the issue that the lock has been released and already re-acquired by the
time the woken up backend checks for the lock's state.

Reported-By: Jeff Janes
Analyzed-By: Heikki Linnakangas
Reviewed-By: Heikki Linnakangas
Discussion: 5592DB35.2060401@iki.fi
Backpatch: 9.5, where the lwlock scalability went in

An outer join clause that didn't actually reference the RHS (perhaps only
after constant-folding) could confuse the join order enforcement logic,
leading to wrong query results.  Also, nested occurrences of such things
could trigger an Assertion that on reflection seems incorrect.

Per fuzz testing by Andreas Seltenreich.  The practical use of such cases
seems thin enough that it's not too surprising we've not heard field
reports about it.

This has been broken for a long time, so back-patch to all active branches.

Per complaint from Peter Holzer.  It's useful to cover this special case,
since for a boolean variable "foo", earlier parts of the planner will have
reduced variants like "foo = true" to just "foo", and thus we may fail
to recognize the applicability of a partial index with predicate
"foo IS NOT NULL".

Back-patch to 9.5, but not further; given the lack of previous complaints
this doesn't seem like behavior to change in stable branches.

In many cases, we can implement a semijoin as a plain innerjoin by first
passing the righthand-side relation through a unique-ification step.
However, one of the cases where this does NOT work is where the RHS has
a LATERAL reference to the LHS; that makes the RHS dependent on the LHS
so that unique-ification is meaningless.  joinpath.c understood this,
and so would not generate any join paths of this kind ... but join_is_legal
neglected to check for the case, so it would think that we could do it.
The upshot would be a "could not devise a query plan for the given query"
failure once we had failed to generate any join paths at all for the bogus
join pair.

Back-patch to 9.3 where LATERAL was added.

The PGXS-case directory does not exist in the non-PGXS case, and vice
versa.  Add one or the other, not both.  This is essentially cosmetic.
It makes Makefile.win32 more like the similar Makefile.global code.

Responsibility was formerly split between Makefile.global and pgxs.mk.
As a result of commit b58233c7, in the
PGXS case, these variables were unset while parsing Makefile.global and
callees.  Inclusion of Makefile.custom did not work from PGXS, and the
subtle difference seemed like a recipe for future bugs.  Back-patch to
9.4, where that commit first appeared.

They are marked stable, but since they act on instantaneous state and it
is possible to consult state of transactions as they commit, the results
could change mid-query.  They need to be marked volatile, and this
commit does so.

There would normally be a catversion bump here, but this is so much a
niche feature and I don't believe there's real damage from the incorrect
marking, that I refrained.

Backpatch to 9.5, where commit timestamps where introduced.

Per note from Fujii Masao.

The code was assuming that any NULL value in scan keys was due to IS
NULL or IS NOT NULL, but it turns out to be possible to get them with
other operators too, if they are used in contrived-enough ways.  Easiest
way out of the problem seems to check explicitely for the IS NOT NULL
flag, instead of assuming it must be set if the IS NULL flag is not set,
when a null scan key is found; if neither flag is set, follow the lead
of other index AMs and assume that all indexable operators must be
strict, and thus the query is never satisfiable.

Also, add a comment to try and lure some future hacker into improving
analysis of scan keys in brin.

Per report from Andreas Seltenreich; diagnosis by Tom Lane.
Backpatch to 9.5.

Discussion: http://www.postgresql.org/message-id/20646.1437919632@sss.pgh.pa.us

Patch by Dean Rasheed. Back-patched to 9.5 where RLS was introduced.

When retrieving policies, if not working on the root target relation,
we actually want the relation's SELECT policies, regardless of
the top level query command type. For example in UPDATE t1...FROM t2
we need to apply t1's UPDATE policies and t2's SELECT policies.
Previously top level query command type was applied to all relations,
which was wrong. Add some regression coverage to ensure we don't
violate this principle in the future.

Report and patch by Dean Rasheed. Cherry picked from larger refactoring
patch and tweaked by me. Back-patched to 9.5 where RLS was introduced.

Although I think on all modern machines floating division by zero
results in Infinity not SIGFPE, we still don't want infinities
running around in the planner's costing estimates; too much risk
of that leading to insane behavior.

grouping_planner() failed to consider the possibility that final_rel
might be known dummy and hence have zero rowcount.  (I wonder if it
would be better to set a rows estimate of 1 for dummy relations?
But at least in the back branches, changing this convention seems
like a bad idea, so I'll leave that for another day.)

Make certain that get_variable_numdistinct() produces a nonzero result.
The case that can be shown to be broken is with stadistinct < 0.0 and
small ntuples; we did not prevent the result from rounding to zero.
For good luck I applied clamp_row_est() to all the nonconstant return
values.

In ExecChooseHashTableSize(), Assert that we compute positive nbuckets
and nbatch.  I know of no reason to think this isn't the case, but it
seems like a good safety check.

Per reports from Piotr Stefaniak.  Back-patch to all active branches.

When we loop back to the top of doCustom after processing a backslash
command, we must reset the "now" timestamp, because that's used to
calculate the time spent executing the previous command.

Report and fix by Fabien Coelho. Backpatch to 9.5, where this was broken.

The current version is adding a spurious -pthread option on some Darwin
systems that don't need it, which leads to a bunch of "unrecognized option
'-pthread'" warnings. There is a proposed fix for that in the upstream
autoconf archive's bug tracker, see https://savannah.gnu.org/patch/?8186.
This commit updates our version of ax_pthread.m4 to the "draft2" version
proposed there by Daniel Richard G. I'm using our buildfarm to help Daniel
to test this, before he commits this to the upstream repository.

Per a suggestion from Tom Lane.  Back-patch to 9.0 (all supported
versions).  While only 9.4 and up have code known to elicit this
compiler bug, we were disabling inlining by accident until commit
43d89a23.

A top-level "make install" includes pg_upgrade since commit
9fa8b0ee.  Back-patch to 9.5, where that
commit first appeared.

The reverted changes did not narrow the semantic gap between the MSVC
build system and the GNU make build system.  For targets old and new
that run multiple suites (contribcheck, modulescheck, tapcheck), restore
vcregress.pl to mimicking "make -k" rather than the "make -S" default.
Lack of "-k" would be more burdensome than lack of "-S".  Keep changes
reflecting contemporary changes to the GNU make build system, and keep
updates to Makefile parsing.  Keep the loss of --psqldir in "check" and
"ecpgcheck" targets; it had been a no-op when used alongside
--temp-install.  No log message mentioned any of the reverted changes.
Based on a germ by Michael Paquier.  Back-patch to 9.5.

Back-patch to 9.5, where commit 4cb7d671
introduced it.

This code relied on knowing exactly where in the source tree temporary
installations might appear.  A reasonable hacker may not think to update
this code when adding use of a temporary installation, making it
fragile.  Observe that commit 9fa8b0ee
broke it unnoticed, and commit dcae5fac
fixed it unnoticed.  Back-patch to 9.5 only; use of temporary
installations is unlikely to change in released versions.

Fabrízio de Royes Mello, reviewed by Payal Singh, Alvaro Herrera and
Michael Paquier.

Policy USING and WITH CHECK expressions were using EXPR_KIND_WHERE for
parse analysis, which results in inappropriate ERROR messages when
the expression contains unsupported constructs such as aggregates.
Create a new ParseExprKind called EXPR_KIND_POLICY and tailor the
related messages to fit.

Reported by Noah Misch. Reviewed by Dean Rasheed, Alvaro Herrera,
and Robert Haas. Back-patch to 9.5 where RLS was introduced.

Amit Langote

Make it more clear that bgw_main is usually not what you want.  Put the
background worker flags in a variablelist rather than having them as
part of a paragraph.  Explain important limits on how bgw_main_arg can
be used.

Craig Ringer, substantially revised by me.

I neglected that the prove_installcheck rule also needs to also define
PG_REGRESS, like prove_check does.

A Salesforce colleague of mine griped that the regression tests don't
exercise EvalPlanQualFetchRowMarks() and allied routines.  Which is
a fair complaint.  Add test cases that go through the REFERENCE and COPY
code paths.  Unfortunately we don't have sufficient infrastructure right
now to exercise the FDW code path in the isolation tests, but this is
surely better than before.

AlterPolicy() and CreatePolicy() lacked their respective hook invocations.
Noted by Noah Misch, review by Dean Rasheed. Back-patch to 9.5 where
RLS was introduced.

On Windows, use listen_address=127.0.0.1 to allow TCP connections. We were
already using "pg_regress --config-auth" to set up HBA appropriately. The
standard_initdb helper function now sets up the server's
unix_socket_directories or listen_addresses in the config file, so that
they don't need to be specified in the pg_ctl command line anymore. That
way, the pg_ctl invocations in test programs don't need to differ between
Windows and Unix.

Add another helper function to configure the server's pg_hba.conf to allow
replication connections. The configuration is done similarly to "pg_regress
--config-auth": trust on domain sockets on Unix, and SSPI authentication on
Windows.

Replace calls to "cat" and "touch" programs with built-in perl code, as
those programs don't normally exist on Windows.

Add instructions in the docs on how to install IPC::Run on Windows. Adjust
vcregress.pl to not replace PERL5LIB completely in vcregress.pl, because
otherwise cannot install IPC::Run in a non-standard location easily.

Michael Paquier, reviewed by Noah Misch, some additional tweaking by me.

Craig Ringer

Noticed-By: Robert Haas
Backpatch: 9.5, where the function was added

Amit Langote