Make REPLICATION privilege checks test current user not authenticated user.

The pg_start_backup() and pg_stop_backup() functions checked the privileges
of the initially-authenticated user rather than the current user, which is
wrong.  For example, a user-defined index function could successfully call
these functions when executed by ANALYZE within autovacuum.  This could
allow an attacker with valid but low-privilege database access to interfere
with creation of routine backups.  Reported and fixed by Noah Misch.

Security: CVE-2013-1901
Fix insecure parsing of server command-line switches.

An oversight in commit e710b65c1c56ca7b91f662c63d37ff2e72862a94 allowed
database names beginning with "-" to be treated as though they were secure
command-line switches; and this switch processing occurs before client
authentication, so that even an unprivileged remote attacker could exploit
the bug, needing only connectivity to the postmaster's port.  Assorted
exploits for this are possible, some requiring a valid database login,
some not.  The worst known problem is that the "-r" switch can be invoked
to redirect the process's stderr output, so that subsequent error messages
will be appended to any file the server can write.  This can for example be
used to corrupt the server's configuration files, so that it will fail when
next restarted.  Complete destruction of database tables is also possible.

Fix by keeping the database name extracted from a startup packet fully
separate from command-line switches, as had already been done with the
user name field.

The Postgres project thanks Mitsumasa Kondo for discovering this bug,
Kyotaro Horiguchi for drafting the fix, and Noah Misch for recognizing
the full extent of the danger.

Security: CVE-2013-1899
Update release notes for 9.2.4, 9.1.9, 9.0.13, 8.4.17.

Security: CVE-2013-1899, CVE-2013-1901
Minor robustness improvements for isolationtester.

Notice and complain about PQcancel() failures.  Also, don't dump core if
an error PGresult doesn't contain severity and message subfields, as it
might not if it was generated by libpq itself.  (We have a longstanding
TODO item to improve that, but in the meantime isolationtester had better
cope.)

I tripped across the latter item while investigating a trouble report on
buildfarm member spoonbill.  As for the former, there's no evidence that
PQcancel failure is actually involved in spoonbill's problem, but it still
seems like a bad idea to ignore an error return code.
Fix typo in FDW docs.

Laurenz Albe
Avoid updating our PgBackendStatus entry when track_activities is off.

The point of turning off track_activities is to avoid this reporting
overhead, but a thinko in commit 4f42b546fd87a80be30c53a0f2c897acb826ad52
caused pgstat_report_activity() to perform half of its updates anyway.
Fix that, and also make sure that we clear all the now-disabled fields
when transitioning to the non-reporting state.
Calculate # of semaphores correctly with --disable-spinlocks.

The old formula didn't take into account that each WAL sender process needs
a spinlock. We had also already exceeded the fixed number of spinlocks
reserved for misc purposes (10). Bump that to 30.

Backpatch to 9.0, where WAL senders were introduced. If I counted correctly,
9.0 had exactly 10 predefined spinlocks, and 9.1 exceeded that, but bump the
limit in 9.0 too because 10 is uncomfortably close to the edge.
Fix a few thinkos in the JSON functions docs.

Dickson S. Guedes
Fix crash on compiling a regular expression with more than 32k colors.

Throw an error instead.

Backpatch to all supported branches.
psql:  fix startup crash caused by PSQLRC containing a tilde

'strdup' the PSQLRC environment variable value before calling a routine
that might free() it.

Backpatch to 9.2, where the bug first appeared.
Fix off by one error in JSON extract path code.

Bug report by David Wheeler, diagnosis assistance from Tom Lane.
Add \watch [SEC] command to psql.

This allows convenient re-execution of commands.

Will Leinweber, reviewed by Peter Eisentraut, Daniel Farina, and Tom Lane
Fix line count in slashUsage().

Counting newlines shows that quite a few recent patches have neglected
to update the output-lines count given to PageOutput().  Fortunately
it's not terribly critical that this be exact, since we long since
exceeded the height of most people's terminal windows.  Still, maybe
we ought to think of a way to not have to maintain this manually anymore.
doc: Fix number of columns in table
Improve documentation about the relationship of extensions and schemas.

There's been some confusion expressed about this point, so clarify.
Extended version of a patch by David Wheeler.
sepgsql: Enforce db_schema:search permission.

KaiGai Kohei, with comment and doc wordsmithing by me
In isolationtester, retry after EINTR return from select(2).

Per report from Jaime Casanova.  Very curious that no one else has seen
this failure ... but the code is clearly wrong as-is.
Get rid of USE_WIDE_UPPER_LOWER dependency in trigram construction.

contrib/pg_trgm's make_trigrams() was coded to ignore multibyte character
boundaries and just make trigrams from bytes if USE_WIDE_UPPER_LOWER wasn't
defined.  This is a bit odd, since there's no obvious reason why trigram
compaction rules should depend on the presence of towlower() and friends.
What's more, there was an Assert() that would fail if that code path was
fed any multibyte characters.

We need to do something about this since the pending regex-indexing patch
has an assumption that you get just one "trgm" from any three characters.
The best solution seems to be to remove the USE_WIDE_UPPER_LOWER
dependency, which shouldn't really have been there in the first place.
The second loop in make_trigrams() is now just a fast path and not a
potentially incompatible algorithm.

If there is anybody still using Postgres on machines without wcstombs() or
towlower(), and they have non-ASCII data indexed by pg_trgm, they'll need
to REINDEX those indexes after pg_upgrade to 9.3, else searches may fail
incorrectly. It seems likely that there are no such installations, though.

In passing, rename cnt_trigram to compact_trigram, which seems to better
describe its functionality, and improve make_trigrams' test for whether it
has to use the slow path or not (per a suggestion from Alexander Korotkov).
Fix checksums for CLUSTER, VACUUM FULL etc.
In CLUSTER, VACUUM FULL and ALTER TABLE SET TABLESPACE
I erroneously set checksum before log_newpage, which
sets the LSN and invalidates the checksum. So set
checksum immediately *after* log_newpage.

Bug report Fujii Masao, Fix and patch by Jeff Davis
Tune BufferGetLSNAtomic() when checksums !enabled

From performance analysis by Heikki Linnakangas