Since the postmaster won't perform a crash-and-restart sequence
for background workers which don't request shared memory access,
we'd better make sure that they can't corrupt shared memory.

Patch by me, review by Tom Lane.

ActiveSnapshot needs to be set when we call ExecutorRewind because some
plan node types may execute user-defined functions during their ReScan
calls (nodeLimit.c does so, at least).  The wisdom of that is somewhat
debatable, perhaps, but for now the simplest fix is to make sure the
required context is valid.  Failure to do this typically led to a
null-pointer-dereference core dump, though it's possible that in more
complex cases a function could be executed with the wrong snapshot
leading to very subtle misbehavior.

Per report from Leif Jensen.  It's been broken for a long time, so
back-patch to all active branches.

The motivation for a crash and restart cycle when a backend dies is
that it might have corrupted shared memory on the way down; and we
can't recover reliably except by reinitializing everything.  But that
doesn't apply to processes that don't touch shared memory.  Currently,
there's nothing to prevent a background worker that doesn't request
shared memory access from touching shared memory anyway, but that's a
separate bug.

Previous to this commit, the coding in postmaster.c was inconsistent:
an exit status other than 0 or 1 didn't provoke a crash-and-restart,
but failure to release the postmaster child slot did.  This change
makes those cases consistent.

Commit 4318daec introduced a test that
couldn't be made consistent between integer and floating-point
timestamps.

It was designed to test the longest possible interval output length,
so removing four zeros from the number of hours, as this patch does,
is not ideal. But the test still has some utility for its original
purpose, and there aren't a lot of other good options.

Noah Misch suggested a different approach where we test that the
output either matches what we expect from integer timestamps or what
we expect from floating-point timestamps. That seemed to obscure an
otherwise simple test, however.

Reviewed by Tom Lane and Noah Misch.

The coding in JsonbHashScalarValue might have accidentally failed to fail
given current representational choices, but the key word there would be
"accidental".  Insert the appropriate datatype conversion macro.  And
use the right conversion macro for hash_numeric's result, too.

In passing make the code a bit cleaner and less repetitive by factoring
out the xor step from the switch.

Index-only scans avoid taking a lock on the VM buffer, which would
cause a lot of contention. To be correct, that requires some intricate
assumptions that weren't completely documented in the previous
comment.

Reviewed by Robert Haas.

The main problem is that DocBook SGML allows indexterm elements just
about everywhere, but DocBook XML is stricter.  For example, this common
pattern

    <varlistentry>
     <indexterm>...</indexterm>
     <term>...</term>
     ...
    </varlistentry>

needs to be changed to something like

    <varlistentry>
     <term>...<indexterm>...</indexterm></term>
     ...
    </varlistentry>

See also bb4eefe7.

There is currently nothing in the build system that enforces that things
stay valid, because that requires additional tools and will receive
separate consideration.

Report by Tom Lane

Report by Tom Lane

Allow for translatable string, rather than use "or"

The previous coding would potentially cause attaching to segment A to
fail if segment B was at the same time in the process of going away.

Andres Freund, with a comment tweak by me

Fix for commit 14ea8936

Report by Andres Freund

This includes removing tabs after periods in C comments, which was
applied to back branches, so this change should not effect backpatching.

Report by Noah Misch

Logic is correct, matching handling of LP_DEAD elsewhere.

Report by Amit Langote

Commit d298b50a by Heikki Linnakangas
requested that the version check message be updated at next release, suggesting
that the appropriate text would be “9.3 or later”. The logic used for the check
indicates that the correct text for 9.4 is “9.3 or 9.4”, since the logic would
cause this to fail for later releases.

Found via valgrind. The bug exists since the introduction of the walsender,
so backpatch to 9.0.

Andres Freund

When array of char * was used as target for a FETCH statement returning more
than one row, it tried to store all the result in the first element. Instead it
should dump array of char pointers with right offset, use the address instead
of the value of the C variable while reading the array and treat such variable
as char **, instead of char * for pointer arithmetic.

Patch by Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>

Previously some I/O errors were ignored.

Heikki updated configure.in but evidently forgot to include the updated
configure script in the commit.  Per buildfarm.

Commit fad153ec modified sinval.c to reduce
the number of calls into sinvaladt.c (which require taking a shared lock)
by keeping a local buffer of collected-but-not-yet-processed messages.
However, if processing of the last message in a batch resulted in a
recursive call to ReceiveSharedInvalidMessages, we could overwrite that
message with a new one while the outer invalidation function was still
working on it.  This would be likely to lead to invalidation of the wrong
cache entry, allowing subsequent processing to use stale cache data.
The fix is just to make a local copy of each message while we're processing
it.

Spotted by Andres Freund.  Back-patch to 8.4 where the bug was introduced.

Commit 261c7d4b removed the "m" field
from struct LINE, but neglected to make pg_type.h's idea of the type's
size match.  This resulted in reading past the end of palloc'd LINE
values when inserting them into tuples etc.  In principle that could
cause a SIGSEGV, though the odds of detectable problems seem low.

Bump catversion since this makes an incompatible on-disk format change.
Note that if the line type had been in use in the field, this would
break pg_upgrade'ability of databases containing line values; but
it seems unlikely that there are any (they'd have had to be compiled
with -DENABLE_LINE_TYPE).

Spotted by Andres Freund.

This was accidentally broken in commits cfa1b4a7/5e8e794e.
It saves a line or so to call ftello unconditionally in _CloseArchive,
but we have to expect that it might fail if we're not in hasSeek mode.
Per report from Bernd Helmle.

In passing, improve _getFilePos to print an appropriate message if
ftello fails unexpectedly, rather than just a vague complaint about
"ftell mismatch".

Etsuro Fujita

This is entirely harmless, but still wrong. Noticed by coverity.

Andres Freund

Andres Freund, noticed by coverity.

Silences coverity and is more consistent with other functions in the
same file.

Andres Freund