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

This option specifies a replication slot for WAL streaming (-X stream),
so that there can be continuous replication slot use between WAL
streaming during the base backup and the start of regular streaming
replication.
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

Buildfarm indicates this is necessary.

Also re-pgindent, just because I'm a neatnik.

When DefineQueryRewrite() is about to convert a table to a view, it checks
the table for features unavailable to views.  For example, it rejects tables
having triggers.  It omits to reject tables having relrowsecurity or a
pg_policy record. Fix that. To faciliate the repair, invent
relation_has_policies() which indicates the presence of policies on a
relation even when row security is disabled for that relation.

Reported by Noah Misch. Patch by me, review by Stephen Frost. Back-patch
to 9.5 where RLS was introduced.

CreatePolicy() and AlterPolicy() omit to create a pg_shdepend entry for
each role in the TO clause. Fix this by creating a new shared dependency
type called SHARED_DEPENDENCY_POLICY and assigning it to each role.

Reported by Noah Misch. Patch by me, reviewed by Alvaro Herrera.
Back-patch to 9.5 where RLS was introduced.

Although initdb has long discouraged use of a filesystem mount-point
directory as a PG data directory, this point was covered nowhere in the
user-facing documentation.  Also, with the popularity of pg_upgrade,
we really need to recommend that the PG user own not only the data
directory but its parent directory too.  (Without a writable parent
directory, operations such as "mv data data.old" fail immediately.
pg_upgrade itself doesn't do that, but wrapper scripts for it often do.)

Hence, adjust the "Creating a Database Cluster" section to address
these points.  I also took the liberty of wordsmithing the discussion
of NFS a bit.

These considerations aren't by any means new, so back-patch to all
supported branches.

The previous code resulted in memory access beyond the path bounds. The
cure is to move it into a code branch that checks the value of lex_level
is within the correct bounds.

Bug reported and diagnosed by Piotr Stefaniak.

Don't print a WARNING if we get ESRCH from a kill() that's attempting
to cancel an autovacuum worker.  It's possible (and has been seen in the
buildfarm) that the worker is already gone by the time we are able to
execute the kill, in which case the failure is harmless.  About the only
plausible reason for reporting such cases would be to help debug corrupted
lock table contents, but this is hardly likely to be the most important
symptom if that happens.  Moreover issuing a WARNING might scare users
more than is warranted.

Also, since sending a signal to an autovacuum worker is now entirely a
routine thing, and the worker will log the query cancel on its end anyway,
reduce the message saying we're doing that from LOG to DEBUG1 level.

Very minor cosmetic cleanup as well.

Since the main practical reason for doing this is to avoid unnecessary
buildfarm failures, back-patch to all active branches.

As pointed out by Tom, since HEAD has progressed beyond 9.5 in terms of
its catalog, we need to be sure catversion of HEAD is advanced beyond
that of 9.5. Corrects my mistake in the pg_stats view commit cfa928ff.

The pg_stats view is supposed to be restricted to only show rows
about tables the user can read. However, it sometimes can leak
information which could not otherwise be seen when row level security
is enabled. Fix that by not showing pg_stats rows to users that would
be subject to RLS on the table the row is related to. This is done
by creating/using the newly introduced SQL visible function,
row_security_active().

Along the way, clean up three call sites of check_enable_rls(). The second
argument of that function should only be specified as other than
InvalidOid when we are checking as a different user than the current one,
as in when querying through a view. These sites were passing GetUserId()
instead of InvalidOid, which can cause the function to return incorrect
results if the current user has the BYPASSRLS privilege and row_security
has been set to OFF.

Additionally fix a bug causing RI Trigger error messages to unintentionally
leak information when RLS is enabled, and other minor cleanup and
improvements. Also add WITH (security_barrier) to the definition of pg_stats.

Bumped CATVERSION due to new SQL functions and pg_stats view definition.

Back-patch to 9.5 where RLS was introduced. Reported by Yaroslav.
Patch by Joe Conway and Dean Rasheed with review and input by
Michael Paquier and Stephen Frost.

While postgres' use of SSL renegotiation is a good idea in theory, it
turned out to not work well in practice. The specification and openssl's
implementation of it have lead to several security issues. Postgres' use
of renegotiation also had its share of bugs.

Additionally OpenSSL has a bunch of bugs around renegotiation, reported
and open for years, that regularly lead to connections breaking with
obscure error messages. We tried increasingly complex workarounds to get
around these bugs, but we didn't find anything complete.

Since these connection breakages often lead to hard to debug problems,
e.g. spuriously failing base backups and significant latency spikes when
synchronous replication is used, we have decided to change the default
setting for ssl renegotiation to 0 (disabled) in the released
backbranches and remove it entirely in 9.5 and master.

Author: Andres Freund
Discussion: 20150624144148.GQ4797@alap3.anarazel.de
Backpatch: 9.5 and master, 9.0-9.4 get a different patch

Given this it is possible that the buildfarm animals running these tests
will be able to capture adequate logging to allow diagnosis of failures.

This code was originally written as part of parallel query effort, but
it seems to have independent value, because if we make one decision
about where to get a PGPROC when we allocate and then put it back on a
different list at backend-exit time, bad things happen.  This isn't
just a theoretical risk; we fixed an actual problem of this type in
commit e280c630.

join_clause_is_movable_into() is approximate, in the sense that it might
sometimes return "false" when actually it would be valid to push the given
join clause down to the specified level.  This is okay ... but there was
an Assert in get_joinrel_parampathinfo() that's only safe if the answers
are always exact.  Comment out the Assert, and add a bunch of commentary
to clarify what's going on.

Per fuzz testing by Andreas Seltenreich.  The added regression test is
a pretty silly query, but it's based on his crasher example.

Back-patch to 9.2 where the faulty logic was introduced.

This was broken in 1bc90f7a, which removed the thread-emulation. With modest
-j and -c settings the result were usually close enough that you wouldn't
notice it easily, but with a high enough thread count it would access
uninitialized memory and crash.

Per report from Andres Freund offlist.

max_block_id is also reset between reading records.

Michael Paquier

pg_dump neglected to wrap parenthesis around USING and WITH CHECK
expressions -- fixed. Reported by Noah Misch.

To avoid a race condition where the relation being COPY'd could be
changed into a view or otherwise modified, keep the original lock
on the relation.  Further, fully qualify the relation when building
the query up.

Also remove the poorly thought-out Assert() and check the entire
relationOids list as, post-RLS, there can certainly be multiple
relations involved and the planner does not guarantee their ordering.

Per discussion with Noah and Andres.

Back-patch to 9.5 where RLS was introduced.