The malloc request was 1 byte too small for the worst-case output.
This seems relatively unlikely to cause any problems in practice,
as the worst case only occurs if the input string contains no
characters other than single-quote or newline, and even then
malloc alignment padding would probably save the day. But it's
definitely a bug.
David Rowley
Apparently, this is a very common mistake for users to make; it is
better to have it fail reasonably rather than throw potentially a large
number of errors. Since we have a magic string at the start of the
file, we can detect the case easily and there's no other possible useful
behavior anyway.
Author: Craig Ringer
This commit simply removes the second argument of PSQLexec that was
set to the same value everywhere. Comments and code blocks related
to this parameter are removed.
Noticed by Heikki Linnakangas, reviewed by Michael Paquier
Revert the output of the individual backslash commands that change print
settings back to the 9.3 way (not showing the command name in
parentheses). Implement \pset without arguments separately, showing all
settings with values in a table form.
Previously pg_receivexlog created new connection for WAL streaming
even though another connection which had been established to create
or delete the replication slot was being left. This caused the unused
connection to be left uselessly until pg_receivexlog exited.
This bug was introduced by the commit d9f38c7.
This patch changes pg_receivexlog so that the connection for
the replication slot is reused for WAL streaming.
Andres Freund, slightly modified by me, reviewed by Michael Paquier
This reverts nearly all of commit 28f6cab61a
in favor of just using the typrelid we already have in pg_dump's TypeInfo
struct for the composite type. As coded, it'd crash if the composite type
had no attributes, since then the query would return no rows.
Back-patch to all supported versions. It seems to not really be a problem
in 9.0 because that version rejects the syntax "create type t as ()", but
we might as well keep the logic similar in all affected branches.
Report and fix by Rushabh Lathia.
pg_dump had the wrong character for update and so was failing when
attempts were made to pg_dump databases with UPDATE policies.
Pointed out by Fujii Masao (thanks!)
Most pg_dump.c global variables, which were passed down individually to
dumping routines, are now grouped as members of the new DumpOptions
struct, which is used as a local variable and passed down into routines
that need it. This helps future development efforts; in particular it
is said to enable a mode in which a parallel pg_dump run can output
multiple streams, and have them restored in parallel.
Also take the opportunity to clean up the pg_dump header files somewhat,
to avoid circularity.
Author: Joachim Wieland, revised by Álvaro Herrera
Reviewed by Peter Eisentraut
List the actions first, as they are the most important options. Group
the other options more sensibly, consistent with the man page. Correct
a few typographical errors, clarify some things.
Also update the pg_receivexlog --help output to make it a bit more
consistent with that of pg_recvlogical.
CreateReplicationSlot() and DropReplicationSlot() were not cleaning up
the query buffer in some cases (mostly error conditions) which meant a
small leak. Not generally an issue as the error case would result in an
immediate exit, but not difficult to fix either and reduces the number
of false positives from code analyzers.
In passing, also add appropriate PQclear() calls to RunIdentifySystem().
Pointed out by Coverity.
pg_receivexlog already has the capability to use a replication slot to
reserve WAL on the upstream node. But the used slot currently has to
be created via SQL.
To allow using slots directly, without involving SQL, add
--create-slot and --drop-slot actions, analogous to the logical slot
manipulation support in pg_recvlogical.
Author: Michael Paquier
Discussion: CABUevEx+zrOHZOQg+dPapNPFRJdsk59b=TSVf30Z71GnFXhQaw@mail.gmail.com
A future patch (9.5 only) adds slot management to pg_receivexlog. The
verbs create/drop don't seem descriptive enough there. It seems better
to rename pg_recvlogical's commands now, in beta, than live with the
inconsistency forever.
The old form (e.g. --drop) will still be accepted by virtue of most
getopt_long() options accepting abbreviations for long commands.
Backpatch to 9.4 where pg_recvlogical was introduced.
Author: Michael Paquier and Andres Freund
Discussion: CAB7nPqQtt79U6FmhwvgqJmNyWcVCbbV-nS72j_jyPEopERg9rg@mail.gmail.com
Peter G pointed out that valgrind was, rightfully, complaining about
CreatePolicy() ending up copying beyond the end of the parsed policy
name. Name is a fixed-size type and we need to use namein (through
DirectFunctionCall1()) to flush out the entire array before we pass
it down to heap_form_tuple.
Michael Paquier pointed out that pg_dump --verbose was missing a
newline and Fabrízio de Royes Mello further pointed out that the
schema was also missing from the messages, so fix those also.
Also, based on an off-list comment from Kevin, rework the psql \d
output to facilitate copy/pasting into a new CREATE or ALTER POLICY
command.
Lastly, improve the pg_policies view and update the documentation for
it, along with a few other minor doc corrections based on an off-list
discussion with Adam Brightwell.
Move some more code to manage replication connection command to
streamutil.c. A later patch will introduce replication slot via
pg_receivexlog and this avoid duplicating relevant code between
pg_receivexlog and pg_recvlogical.
Author: Michael Paquier, with some editing by me.
Several comments still referred to 'initiating', 'freeing', 'stopping'
replication slots. These were terms used during different phases of
the development of logical decoding, but are no long accurate.
Also rename StreamLog() to StreamLogicalLog() and add 'void' to the
prototype.
Author: Michael Paquier, with some editing by me.
Backpatch to 9.4 where pg_recvlogical was introduced.
Andres pointed out that there was an extra ';' in equalPolicies, which
made me realize that my prior testing with CLOBBER_CACHE_ALWAYS was
insufficient (it didn't always catch the issue, just most of the time).
Thanks to that, a different issue was discovered, specifically in
equalRSDescs. This change corrects eqaulRSDescs to return 'true' once
all policies have been confirmed logically identical. After stepping
through both functions to ensure correct behavior, I ran this for
about 12 hours of CLOBBER_CACHE_ALWAYS runs of the regression tests
with no failures.
In addition, correct a few typos in the documentation which were pointed
out by Thom Brown (thanks!) and improve the policy documentation further
by adding a flushed out usage example based on a unix passwd file.
Lastly, clean up a few comments in the regression tests and pg_dump.h.
Without this fix, parallel restore of a schema-only dump can deadlock,
because when the dump is schema-only, the dependency will still be
pointing at the TABLE item rather than the TABLE DATA item.
Robert Haas and Tom Lane
It was confusing that to other commands, like initdb and postgres, you would
pass the data directory with "-D datadir", but pg_controldata and
pg_resetxlog would take just plain path, without the "-D". With this patch,
pg_controldata and pg_resetxlog also accept "-D datadir".
Abhijit Menon-Sen, with minor kibitzing by me
Buildfarm member tick identified an issue where the policies in the
relcache for a relation were were being replaced underneath a running
query, leading to segfaults while processing the policies to be added
to a query. Similar to how TupleDesc RuleLocks are handled, add in a
equalRSDesc() function to check if the policies have actually changed
and, if not, swap back the rsdesc field (using the original instead of
the temporairly built one; the whole structure is swapped and then
specific fields swapped back). This now passes a CLOBBER_CACHE_ALWAYS
for me and should resolve the buildfarm error.
In addition to addressing this, add a new chapter in Data Definition
under Privileges which explains row security and provides examples of
its usage, change \d to always list policies (even if row security is
disabled- but note that it is disabled, or enabled with no policies),
rework check_role_for_policy (it really didn't need the entire policy,
but it did need to be using has_privs_of_role()), and change the field
in pg_class to relrowsecurity from relhasrowsecurity, based on
Heikki's suggestion. Also from Heikki, only issue SET ROW_SECURITY in
pg_restore when talking to a 9.5+ server, list Bypass RLS in \du, and
document --enable-row-security options for pg_dump and pg_restore.
Lastly, fix a number of minor whitespace and typo issues from Heikki,
Dimitri, add a missing #include, per Peter E, fix a few minor
variable-assigned-but-not-used and resource leak issues from Coverity
and add tab completion for role attribute bypassrls as well.
In a2dabf0 we added the ability to have single or double unicode
linestyle for the border, column, or header. Unfortunately, the
\? variables output was not updated for these new psql variables.
This corrects that oversight.
Patch by Pavel Stehule.
Building on the updatable security-barrier views work, add the
ability to define policies on tables to limit the set of rows
which are returned from a query and which are allowed to be added
to a table. Expressions defined by the policy for filtering are
added to the security barrier quals of the query, while expressions
defined to check records being added to a table are added to the
with-check options of the query.
New top-level commands are CREATE/ALTER/DROP POLICY and are
controlled by the table owner. Row Security is able to be enabled
and disabled by the owner on a per-table basis using
ALTER TABLE .. ENABLE/DISABLE ROW SECURITY.
Per discussion, ROW SECURITY is disabled on tables by default and
must be enabled for policies on the table to be used. If no
policies exist on a table with ROW SECURITY enabled, a default-deny
policy is used and no records will be visible.
By default, row security is applied at all times except for the
table owner and the superuser. A new GUC, row_security, is added
which can be set to ON, OFF, or FORCE. When set to FORCE, row
security will be applied even for the table owner and superusers.
When set to OFF, row security will be disabled when allowed and an
error will be thrown if the user does not have rights to bypass row
security.
Per discussion, pg_dump sets row_security = OFF by default to ensure
that exports and backups will have all data in the table or will
error if there are insufficient privileges to bypass row security.
A new option has been added to pg_dump, --enable-row-security, to
ask pg_dump to export with row security enabled.
A new role capability, BYPASSRLS, which can only be set by the
superuser, is added to allow other users to be able to bypass row
security using row_security = OFF.
Many thanks to the various individuals who have helped with the
design, particularly Robert Haas for his feedback.
Authors include Craig Ringer, KaiGai Kohei, Adam Brightwell, Dean
Rasheed, with additional changes and rework by me.
Reviewers have included all of the above, Greg Smith,
Jeff McCormick, and Robert Haas.
With the unicode linestyle, this adds support to control if the
column, header, or border style should be single or double line
unicode characters. The default remains 'single'.
In passing, clean up the border documentation and address some
minor formatting/spelling issues.
Pavel Stehule, with some additional changes by me.
In psql, expanded mode was not being displayed correctly when using
the normal ascii or unicode linestyles and border set to '3'. Now,
per the documentation, border '3' is really only sensible for HTML
and LaTeX formats, however, that's no excuse for ascii/unicode to
break in that case, and provisions had been made for psql to cleanly
handle this case (and it did, in non-expanded mode).
This was broken when ascii/unicode was initially added a good five
years ago because print_aligned_vertical_line wasn't passed in the
border setting being used by print_aligned_vertical but instead was
given the whole printTableContent. There really isn't a good reason
for vertical_line to have the entire printTableContent structure, so
just pass in the printTextFormat and border setting (similar to how
this is handled in horizontal_line).
Pointed out by Pavel Stehule, fix by me.
Back-patch to all currently-supported versions.
When running vacuumdb --analyze-in-stages --all, it needs to run the
first stage across all databases before the second one, instead of
running all stages in a database before processing the next one.
Also respect the --quiet option with --analyze-in-stages.
Add --help=<topic> for the commandline, and \? <topic> as a backslash
command, to show more help than the invocations without parameters
do. "commands", "variables" and "options" currently exist as help
topics describing, respectively, backslash commands, psql variables,
and commandline switches. Without parameters the help commands show
their previous topic.
Some further wordsmithing or extending of the added help content might
be needed; but there seems little benefit delaying the overall feature
further.
Author: Pavel Stehule, editorialized by many
Reviewed-By: Andres Freund, Petr Jelinek, Fujii Masao, MauMau, Abhijit
Menon-Sen and Erik Rijkers.
Discussion: CAFj8pRDVGuC-nXBfe2CK8vpyzd2Dsr9GVpbrATAnZO=2YQ0s2Q@mail.gmail.com,
CAFj8pRA54AbTv2RXDTRxiAd8hy8wxmoVLqhJDRCwEnhdd7OUkw@mail.gmail.com
psql's \s (print command history) doesn't work at all with recent libedit
versions when printing to the terminal, because libedit tries to do an
fchmod() on the target file which will fail if the target is /dev/tty.
(We'd already noted this in the context of the target being /dev/null.)
Even before that, it didn't work pleasantly, because libedit likes to
encode the command history file (to ensure successful reloading), which
renders it nigh unreadable, not to mention significantly different-looking
depending on exactly which libedit version you have. So let's forget using
write_history() for this purpose, and instead print the data ourselves,
using logic similar to that used to iterate over the history for newline
encoding/decoding purposes.
While we're at it, insert the ability to use the pager when \s is printing
to the terminal. This has been an acknowledged shortcoming of \s for many
years, so while you could argue it's not exactly a back-patchable bug fix
it still seems like a good improvement. Anyone who's seriously annoyed
at this can use "\s /dev/tty" or local equivalent to get the old behavior.
Experimentation with this showed that the history iteration logic was
actually rather broken when used with libedit. It turns out that with
libedit you have to use previous_history() not next_history() to advance
to more recent history entries. The easiest and most robust fix for this
seems to be to make a run-time test to verify which function to call.
We had not noticed this because libedit doesn't really need the newline
encoding logic: its own encoding ensures that command entries containing
newlines are reloaded correctly (unlike libreadline). So the effective
behavior with recent libedits was that only the oldest history entry got
newline-encoded or newline-decoded. However, because of yet other bugs in
history_set_pos(), some old versions of libedit allowed the existing loop
logic to reach entries besides the oldest, which means there may be libedit
~/.psql_history files out there containing encoded newlines in more than
just the oldest entry. To ensure we can reload such files, it seems
appropriate to back-patch this fix, even though that will result in some
incompatibility with older psql versions (ie, multiline history entries
written by a psql with this fix will look corrupted to a psql without it,
if its libedit is reasonably up to date).
Stepan Rutz and Tom Lane
Update the tab completion for the changes made in
3c4cf08087, which rework 'MOVE ALL' to be
'ALTER .. ALL IN TABLESPACE'.
Fujii Masao
Back-patch to 9.4, as the original change was.
Previously \watch could not display the query execution time even
when \timing was enabled because it used PSQLexec instead of
SendQuery and that function didn't support \timing. This patch
introduces PSQLexecWatch and changes \watch so as to use it, instead.
PSQLexecWatch is the function to run the query, print its results and
display how long it took (only when \timing is enabled).
This patch also changes --echo-hidden so that it doesn't print
the query that \watch executes. Since \watch cannot execute
backslash command queries, they should not be printed even
when --echo-hidden is set.
Patch by me, review by Heikki Linnakangas and Michael Paquier
The new %l substitution shows the line number inside a (potentially
multi-line) statement starting from one.
Author: Sawada Masahiko, heavily editorialized by me.
Reviewed-By: Jeevan Chalke, Alvaro Herrera
This patch allows us to execute ALTER SYSTEM RESET command to
remove the configuration entry from postgresql.auto.conf.
Vik Fearing, reviewed by Amit Kapila and me.
Add a note that some options can be specified multiple times to select
multiple objects to restore. This replaces the somewhat confusing use
of plurals in the option descriptions themselves.
This enables changing permanent (logged) tables to unlogged and
vice-versa.
(Docs for ALTER TABLE / SET TABLESPACE got shuffled in an order that
hopefully makes more sense than the original.)
Author: Fabrízio de Royes Mello
Reviewed by: Christoph Berg, Andres Freund, Thom Brown
Some tweaking by Álvaro Herrera
Previously, we would first create the symlinks the way they are in the
original system, and at the end replace them with the mapped symlinks.
That never really made much sense, so now we create the symlink pointing
to the correct location to begin with, so that there's no need to fix
them at the end.
The old coding didn't work correctly on Windows, because Windows junction
points look more like directories than files, and ought to be removed with
rmdir rather than unlink. Also, it incorrectly used "%d" rather than "%u"
to print an Oid, but that's gone now.
Report and patch by Amit Kapila, with minor changes by me. Reviewed by
MauMau. Backpatch to 9.4, where the --tablespace feature was added.
This reverts commit 083d29c65b.
The commit changed the code so that it causes an errors when
IDENTIFY_SYSTEM returns three columns. But which prevents us
from using the replication-related utilities against the server
with older version. This is not what we want. For that
compatibility, we allow the utilities to receive three columns
as the result of IDENTIFY_SYSTEM eventhough it actually returns
four columns in 9.4 or later.
Pointed out by Andres Freund.
5a991ef869 added new column into
the result of IDENTIFY_SYSTEM command. But it was not reflected into
several codes checking that result. Specifically though the number of
columns in the result was increased to 4, it was still compared with 3
in some replication codes.
Back-patch to 9.4 where the number of columns in IDENTIFY_SYSTEM
result was increased.
Report from Michael Paquier
Previously the help message described that -m is an option for
"stop", "restart" and "promote" commands in pg_ctl. But actually
that's not an option for "promote". So this commit fixes that
incorrect description in the help message.
Back-patch to 9.3 where the incorrect description was added.
This option is equivalent to --slot option which pg_receivexlog has
already supported, which specifies the replication slot to use for
WAL streaming. pg_recvlogical has already supported both options,
and this commit makes pg_receivexlog consistent with pg_recvlogical
regarding the slot option.
Back-patch to 9.4 where the slot option was added.
Michael Paquier
Some error messages complained about --init and --stop being used
whereas the --create and --drop are the correct verbs. Fix that.
Also a XLogRecPtr was tested in a boolean fashion instead of being
compared to InvalidXLogRecPtr.
Backpatch to 9.4 where pg_recvlogical was introduced.
Michael Paquier
This commit also changes tab-completion for \set so that it displays
all the special variables like COMP_KEYWORD_CASE. Previously it displayed
only variables having the set values. Which was not user-friendly for
those who want to set the unset variables.
This commit also changes tab-completion for :variable so that only the
variables having the set values are displayed. Previously even unset
variables were displayed.
Pavel Stehule, modified by me.
This refactoring is in preparation for adding support for other SSL
implementations, with no user-visible effects. There are now two #defines,
USE_OPENSSL which is defined when building with OpenSSL, and USE_SSL which
is defined when building with any SSL implementation. Currently, OpenSSL is
the only implementation so the two #defines go together, but USE_SSL is
supposed to be used for implementation-independent code.
The libpq SSL code is changed to use a custom BIO, which does all the raw
I/O, like we've been doing in the backend for a long time. That makes it
possible to use MSG_NOSIGNAL to block SIGPIPE when using SSL, which avoids
a couple of syscall for each send(). Probably doesn't make much performance
difference in practice - the SSL encryption is expensive enough to mask the
effect - but it was a natural result of this refactoring.
Based on a patch by Martijn van Oosterhout from 2006. Briefly reviewed by
Alvaro Herrera, Andreas Karlsson, Jeff Janes.
This allows us to specify the maximum time to issue fsync to ensure
the received WAL file is safely flushed to disk. Without this,
pg_receivexlog always flushes WAL file only when it's closed and
which can cause WAL data to be lost at the event of a crash.
Furuya Osamu, heavily modified by me.
Previously the source codes for processing the received data and handling
the end of stream were included in pg_receivexlog main loop. This commit
splits out them as separate functions. This is useful for improving the
readability of main loop code and making the future pg_receivexlog-related
patch simpler.
In 9.2, pg_receivexlog with verbose option has emitted the messages
at the end of each WAL file. But the commit 0b63291 suppressed such
messages by mistake. This commit fixes the bug so that pg_receivexlog
--verbose outputs such messages again.
Back-patch to 9.3 where the bug was added.
findDependencyLoops() was not bright about cases where there are multiple
dependency paths between the same two dumpable objects. In most scenarios
this did not hurt us too badly; but since the introduction of section
boundary pseudo-objects in commit a1ef01fe16,
it was possible for this code to take unreasonable amounts of time (tens
of seconds on a database with a couple thousand objects), as reported in
bug #11033 from Joe Van Dyk. Joe's particular problem scenario involved
"pg_dump -a" mode with long chains of foreign key constraints, but I think
that similar problems could arise with other situations as long as there
were enough objects. To fix, add a flag array that lets us notice when we
arrive at the same object again while searching from a given start object.
This simple change seems to be enough to eliminate the performance problem.
Back-patch to 9.1, like the patch that introduced section boundary objects.
The problem is that pg_receivexlog calls select(2) with timeout=0 and
goes into busy loop when --status-interval option is set to 0. This bug
was introduced by the commit,
74cbe966fe.
Per report from Sawada Masahiko
pg_ctl will log to the Windows event log when it is running as a service,
which is the primary way of running PostgreSQL on Windows. This option
makes it possible to specify which event source to use for this, in order
to separate different instances. The server logging itself is still controlled
by the regular logging parameters, including a separate setting for the event
source. The parameter to pg_ctl only controlls the logging from pg_ctl itself.
MauMau, review in many iterations by Amit Kapila and me.
Both the psql banner and the connection logging already included
SSL status, cipher and bitlength, this adds the information about
compression being on or off.
Prominent binaries already had this metadata. A handful of minor
binaries, such as pg_regress.exe, still lack it; efforts to eliminate
such exceptions are welcome.
Michael Paquier, reviewed by MauMau.
Complete SET search_path = ... to non-temporary and non-toast
schemas. Since there pretty much is no use case to add those to the
search path and there can be many it's helpful to exclude them.
It'd be nicer to complete multiple search path elements, but that's
not easy.
Jeff Janes
This command provides an automated way to create foreign table definitions
that match remote tables, thereby reducing tedium and chances for error.
In this patch, we provide the necessary core-server infrastructure and
implement the feature fully in the postgres_fdw foreign-data wrapper.
Other wrappers will throw a "feature not supported" error until/unless
they are updated.
Ronan Dunklau and Michael Paquier, additional work by me
When the psql variable ECHO is set to 'erros', only failed SQL commands
are printed to standard error output. Also this patch adds -b option into psql.
This is equivalent to setting the variable ECHO to 'errors'.
Pavel Stehule, reviewed by Fabrízio de Royes Mello, Samrat Revagade,
Kumar Rajeev Rastogi, Abhijit Menon-Sen, and me.
We used to print this information only in verbose mode, but it's argued
that it's useful enough to print always; one reason being that this
provides some documentation about which Postgres versions the dump is
meant to reload into.
Jing Wang, reviewed by Jeevan Chalke
Previously the source codes for receiving the data and for
polling the socket were included in pg_receivexlog main loop.
This commit splits out them as separate functions. This is
useful for improving the readability of main loop code and
making the future pg_receivexlog-related patch simpler.
Creating the Unix-domain socket in the build directory can run into
name-length limitations. Therefore, create the socket file in the
default temporary directory of the operating system. Keep the temporary
data directory etc. in the build tree.
The old name wasn't very descriptive as of actual contents of the
directory, which are historical snapshots in the snapshots/
subdirectory and mappingdata for rewritten tuples in
mappings/. There's been a fair amount of discussion what would be a
good name. I'm settling for pg_logical because it's likely that
further data around logical decoding and replication will need saving
in the future.
Also add the missing entry for the directory into storage.sgml's list
of PGDATA contents.
Bumps catversion as the data directories won't be compatible.
The autocommit-off mode works by issuing an implicit BEGIN just before
any command that is not already in a transaction block and is not itself
a BEGIN or other transaction-control command, nor a command that
cannot be executed inside a transaction block. This commit prevents psql
from issuing such an implicit BEGIN before ALTER SYSTEM because it's
not allowed inside a transaction block.
Backpatch to 9.4 where ALTER SYSTEM was added.
Report by Feike Steenbergen
Historically these database properties could be manipulated only by
manually updating pg_database, which is error-prone and only possible for
superusers. But there seems no good reason not to allow database owners to
set them for their databases, so invent CREATE/ALTER DATABASE options to do
that. Adjust a couple of places that were doing it the hard way to use the
commands instead.
Vik Fearing, reviewed by Pavel Stehule
At "DROP RULE/TRIGGER triggername ON ...", tab-complete tables that have
a rule/trigger with that name.
At "ALTER TABLE tablename ENABLE/DISABLE TRIGGER/RULE ...", tab-complete to
rules/triggers on that table. Previously, we would tab-complete to all
rules or triggers, not just those that are on that table.
Also, filter out internal RI triggers from the list. You can't DROP them,
and enabling/disabling them is such a rare (and dangerous) operation that
it seems better to hide them.
Andreas Karlsson, reviewed by Ian Barwick.
Prior to 9.0, pg_dump handled comments on large objects by dumping a bunch
of COMMENT commands into a single BLOB COMMENTS archive object. With
sufficiently many such comments, some of the commands would likely get
split across bufferloads when restoring, causing failures in
direct-to-database restores (though no problem would be evident in text
output). This is the same type of issue we have with table data dumped as
INSERT commands, and it can be fixed in the same way, by using a mini SQL
lexer to figure out where the command boundaries are. Fortunately, the
COMMENT commands are no more complex to lex than INSERTs, so we can just
re-use the existing lexer for INSERTs.
Per bug #10611 from Jacek Zalewski. Back-patch to all active branches.
It's critical that the backend's idea of LOBLKSIZE match the way data has
actually been divided up in pg_largeobject. While we don't provide any
direct way to adjust that value, doing so is a one-line source code change
and various people have expressed interest recently in changing it. So,
just as with TOAST_MAX_CHUNK_SIZE, it seems prudent to record the value in
pg_control and cross-check that the backend's compiled-in setting matches
the on-disk data.
Also tweak the code in inv_api.c so that fetches from pg_largeobject
explicitly verify that the length of the data field is not more than
LOBLKSIZE. Formerly we just had Asserts() for that, which is no protection
at all in production builds. In some of the call sites an overlength data
value would translate directly to a security-relevant stack clobber, so it
seems worth one extra runtime comparison to be sure.
In the back branches, we can't change the contents of pg_control; but we
can still make the extra checks in inv_api.c, which will offer some amount
of protection against running with the wrong value of LOBLKSIZE.
