try_index_open() is able to open an index if its relkind fits, except
that it would return NULL instead of generated an error if the relation
does not exist. This new routine will be used by an upcoming patch to
make REINDEX on partitioned relations more robust when an index in a
partition tree is dropped.
Extracted from a larger patch by the same author.
Author: Fei Changhong
Discussion: https://postgr.es/m/tencent_6A52106095ACDE55333E3AD33F304C0C3909@qq.com
Backpatch-through: 14
Until now LWLockDequeueSelf() sequentially searched the list of waiters to see
if the current proc is still is on the list of waiters, or has already been
removed. In extreme workloads, where the wait lists are very long, this leads
to a quadratic behavior. #backends iterating over a list #backends
long. Additionally, the likelihood of needing to call LWLockDequeueSelf() in
the first place also increases with the increased length of the wait queue, as
it becomes more likely that a lock is released while waiting for the wait list
lock, which is held for longer during lock release.
Due to the exponential back-off in perform_spin_delay() this is surprisingly
hard to detect. We should make that easier, e.g. by adding a wait event around
the pg_usleep() - but that's a separate patch.
The fix is simple - track whether a proc is currently waiting in the wait list
or already removed but waiting to be woken up in PGPROC->lwWaiting.
In some workloads with a lot of clients contending for a small number of
lwlocks (e.g. WALWriteLock), the fix can substantially increase throughput.
This has been originally fixed for 16~ with a4adc31f69 without a
backpatch, and we have heard complaints from users impacted by this
quadratic behavior in older versions as well.
Author: Andres Freund <andres@anarazel.de>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Discussion: https://postgr.es/m/20221027165914.2hofzp4cvutj6gin@awork3.anarazel.de
Discussion: https://postgr.es/m/CALj2ACXktNbG=K8Xi7PSqbofTZozavhaxjatVc14iYaLu4Maag@mail.gmail.com
Backpatch-through: 12
The comment was copy-pasted from the call to ProcSignalInit() in
AuxiliaryProcessMain(), which uses a similar scheme of having reserved
slots for aux processes after MaxBackends slots for backends. However,
ProcSignalInit() indexing starts from 1, whereas BackendStatusArray
starts from 0. The code is correct, but the comment was wrong.
Discussion: https://www.postgresql.org/message-id/f3ecd4cb-85ee-4e54-8278-5fabfb3a4ed0@iki.fi
Backpatch-through: v14
If configuring the newly created socket non-blocking fails we
error out and return INVALID_SOCKET, but the socket that had
been created wasn't closed. Fix by issuing closesocket in the
errorpath.
Backpatch to all supported branches.
Author: Ranier Vilela <ranier.vf@gmail.com>
Discussion: https://postgr.es/m/CAEudQApmU5CrKefH85VbNYE2y8H=-qqEJbg6RAPU65+vCe+89A@mail.gmail.com
Backpatch-through: v12
Commit b8ba7344e9 added in PQgetResult a derefence to a pointer
returned by pqPrepareAsyncResult(), before some other code that was
already testing that pointer for nullness. But since commit
618c16707a (in Postgres 15), pqPrepareAsyncResult() doesn't ever
return NULL (a statically-allocated result is returned if OOM). So in
branches 15 and up, we can remove the redundant pointer check with no
harm done.
However, in branch 14, pqPrepareAsyncResult() can indeed return NULL if
it runs out of memory. Fix things there by adding a null pointer check
before dereferencing the pointer. This should hint Coverity that the
preexisting check is not redundant but necessary.
Backpatch to 14, like b8ba7344e9.
Per Coverity.
When ExecBRUpdateTriggers switches to a new target tuple as a result
of the EvalPlanQual logic, it must form a new proposed update tuple.
Since commit 86dc90056, that tuple (the result of
ExecGetUpdateNewTuple) has been a virtual tuple that might contain
pointers to by-ref fields of the new target tuple (in "oldslot").
However, immediately after that we materialize oldslot, causing it to
drop its buffer pin, whereupon the by-ref pointers are unsafe to use.
This is a live bug only when the new target tuple is in a different
page than the original target tuple, since we do still hold a pin on
the original one. (Before 86dc90056, there was no bug because the
EPQ plantree would hold a pin on the new target tuple; but now that's
not assured.) To fix, forcibly materialize the new tuple before we
materialize oldslot. This costs nothing since we would have done that
shortly anyway.
The real-world impact of this is probably minimal. A visible failure
could occur if the new target tuple's buffer were recycled for some
other page in the short interval before we materialize newslot within
the trigger-calling loop; but that's quite unlikely given that we'd
just touched that page. There's a larger hazard that some other
process could prune and repack that page within the window. We have
lock on the new target tuple, but that wouldn't prevent it being moved
on the page.
Alexander Lakhin and Tom Lane, per bug #17798 from Alexander Lakhin.
Back-patch to v14 where 86dc90056 came in.
Discussion: https://postgr.es/m/17798-0907404928dcf0dd@postgresql.org
We've long had a policy that any toasted fields in a catalog tuple
should be pulled in-line before entering the tuple in a catalog cache.
However, that requires access to the catalog's toast table, and we'll
typically do AcceptInvalidationMessages while opening the toast table.
So it's possible that the catalog tuple is outdated by the time we
finish detoasting it. Since no cache entry exists yet, we can't
mark the entry stale during AcceptInvalidationMessages, and instead
we'll press forward and build an apparently-valid cache entry. The
upshot is that we have a race condition whereby an out-of-date entry
could be made in a backend's catalog cache, and persist there
indefinitely causing indeterminate misbehavior.
To fix, use the existing systable_recheck_tuple code to recheck
whether the catalog tuple is still up-to-date after we finish
detoasting it. If not, loop around and restart the process of
searching the catalog and constructing cache entries from the top.
The case is rare enough that this shouldn't create any meaningful
performance penalty, even in the SearchCatCacheList case where
we need to tear down and reconstruct the whole list.
Indeed, the case is so rare that AFAICT it doesn't occur during
our regression tests, and there doesn't seem to be any easy way
to build a test that would exercise it reliably. To allow
testing of the retry code paths, add logic (in USE_ASSERT_CHECKING
builds only) that randomly pretends that the recheck failed about
one time out of a thousand. This is enough to ensure that we'll
pass through the retry paths during most regression test runs.
By adding an extra level of looping, this commit creates a need
to reindent most of SearchCatCacheMiss and SearchCatCacheList.
I'll do that separately, to allow putting those changes in
.git-blame-ignore-revs.
Patch by me; thanks to Alexander Lakhin for having built a test
case to prove the bug is real, and to Xiaoran Wang for review.
Back-patch to all supported branches.
Discussion: https://postgr.es/m/1393953.1698353013@sss.pgh.pa.us
Discussion: https://postgr.es/m/CAGjhLkOoBEC9mLsnB42d3CO1vcMx71MLSEuigeABbQ8oRdA6gw@mail.gmail.com
This is similar to 9886744a36, to prevent the execution of other
programs due to autorun configurations which could influence the
postmaster startup.
This was originally applied on HEAD as of 83c75ac7fb69 without a
backpatch, but the patch has survived CI and buildfarm cycles. I have
checked that cmd /d exists down to Windows XP, which should make this
change work correctly in the oldest branches still supported.
Discussion: https://postgr.es/m/20230922.161551.320043332510268554.horikyota.ntt@gmail.com
Backpatch-through: 12
On Windows, cmd.exe is used to launch the postmaster process to ease its
redirection setup. However, cmd.exe may execute other programs at
startup due to autorun configurations, which could influence the
postmaster startup. This patch adds /D flag to the launcher cmd.exe
command line to disable autorun settings written in the registry.
This was originally applied on HEAD as of 9886744a36 without a
backpatch, but the patch has survived CI and buildfarm cycles. I have
checked that cmd /d exists down to Windows XP, which should make this
change work correctly in the oldest branches still supported.
Reported-by: Hayato Kuroda
Author: Kyotaro Horiguchi
Reviewed-by: Robert Haas, Michael Paquier
Discussion: https://postgr.es/m/20230922.161551.320043332510268554.horikyota.ntt@gmail.com
Backpatch-through: 12
The code for wrapping subquery output expressions in PlaceHolderVars
believed that if the expression already was a PlaceHolderVar, it was
never necessary to wrap that in another one. That's wrong if the
expression is underneath an outer join and involves a lateral
reference to outside that scope: failing to add an additional PHV
risks evaluating the expression at the wrong place and hence not
forcing it to null when the outer join should do so. This is an
oversight in commit 9e7e29c75, which added logic to forcibly wrap
lateral-reference Vars in PlaceHolderVars, but didn't see that the
adjacent case for PlaceHolderVars needed the same treatment.
The test case we have for this doesn't fail before 4be058fe9, but now
that I see the problem I wonder if it is possible to demonstrate
related errors before that. That's moot though, since all such
branches are out of support.
Per bug #18284 from Holger Reise. Back-patch to all supported
branches.
Discussion: https://postgr.es/m/18284-47505a20c23647f8@postgresql.org
UNIQUE and PRIMARY KEY constraints can be created on ONLY the
partitioned table. We already had an example demonstrating that,
but forgot to mention it in the documentation of the limits of
partitioning.
Author: Laurenz Albe
Reviewed-By: shihao zhong, Shubham Khanna, Ashutosh Bapat
Backpatch-through: 12
Discussion: https://postgr.es/m/167299368731.659.16130012959616771853@wrigleys.postgresql.org
The note regarding character encoding form in "The Information Schema"
said that LATIN1 character repertoires only use one encoding form
LATIN1. This is not correct because LATIN1 has another encoding form
ISO-2022-JP-2. To fix this, replace LATIN1 with LATIN2, which is not
supported by ISO-2022-JP-2, thus it can be said that LATIN2 only uses
one encoding form.
Back-patch to supported branches.
Author: Tatsuo Ishii
Reviewed-by: Daniel Gustafsson
Discussion: https://postgr.es/m/flat/20240102.153925.1147403616414525145.t-ishii%40sranhm.sra.co.jp
An array element equal to INT_MAX gave this code indigestion,
causing an infinite loop that surely ended in SIGSEGV. We fixed
some nearby problems awhile ago (cf 757c5182f) but missed this.
Report and diagnosis by Alexander Lakhin (bug #18273); patch by me
Discussion: https://postgr.es/m/18273-9a832d1da122600c@postgresql.org
During the calculations of the maximum for the number of buckets, take into
account that later we round that to the next power of 2.
Reported-by: Karen Talarico
Bug: #16925
Discussion: https://postgr.es/m/16925-ec96d83529d0d629%40postgresql.org
Author: Thomas Munro, Andrei Lepikhov, Alexander Korotkov
Reviewed-by: Alena Rybakina
Backpatch-through: 12
CheckPWChallengeAuth() would return STATUS_ERROR if the user does not
exist or has no password assigned, even if the client disconnected
without responding to the password challenge (as libpq often will,
for example). We should return STATUS_EOF in that case, and the
lower-level functions do, but this code level got it wrong since the
refactoring done in 7ac955b34. This breaks the intent of not logging
anything for EOF cases (cf. comments in auth_failed()) and might
also confuse users of ClientAuthentication_hook.
Per report from Liu Lang. Back-patch to all supported versions.
Discussion: https://postgr.es/m/b725238c-539d-cb09-2bff-b5e6cb2c069c@esgyn.cn
If the underlying table isn't being dumped, it's useless to dump
an extended statistics object; it'll just cause errors at restore.
We have always applied similar policies to, say, indexes.
(When and if we get cross-table stats objects, it might be profitable
to think a little harder about what to do with them. But for now
there seems no point in considering a stats object as anything but
an appendage of its table.)
Rian McGuire and Tom Lane, per report from Rian McGuire.
Back-patch to supported branches.
Discussion: https://postgr.es/m/7075d3aa-3f05-44a5-b68f-47dc6a8a0550@buildkite.com
The documentation has been missing one value in the list of catalog OIDs
that can be given to the validator function of a FDW, as of
AttributeRelationId, when changing the attribute options of a foreign
table.
Author: Ian Lawrence Barwick
Discussion: https://postgr.es/m/CAB8KJ=i16t2yJU_Pq2Z+hnNGWFhagp_bJmzxHZu3ZkOjZm-+rQ@mail.gmail.com
Backpatch-through: 12
set_config_option() bails out early if it detects that the option to
be set is PGC_BACKEND or PGC_SU_BACKEND class and we're reading the
config file in a postmaster child; we don't want to apply any new
value in such a case. That's fine as far as it goes, but it fails
to consider the requirements of the pg_file_settings view: for that,
we need to check validity of the value even though we have no
intention to apply it. Because we didn't, even very silly values
for affected GUCs would be reported as valid by the view. There
are only half a dozen such GUCs, which perhaps explains why this
got overlooked for so long.
Fix by continuing when changeVal is false; this parallels the logic
in some other early-exit paths.
Also, the check added by commit 924bcf4f1 to prevent GUC changes in
parallel workers seems a few bricks shy of a load: it's evidently
assuming that ereport(elevel, ...) won't return. Make sure we
bail out if it does. The lack of trouble reports suggests that
this is only a latent bug, i.e. parallel workers don't actually
reach here with elevel < ERROR. (Per the code coverage report,
we never reach here at all in the regression suite.) But we clearly
don't want to risk proceeding if that does happen.
Per report from Rıdvan Korkmaz. These are ancient bugs, so back-patch
to all supported branches.
Discussion: https://postgr.es/m/2089235.1703617353@sss.pgh.pa.us
Like commit 388e80132, use "#pragma GCC system_header" to silence
warnings appearing within the Python headers, since newer Python
versions no longer worry about some restrictions we still use like
-Wdeclaration-after-statement.
This patch improves on 388e80132 by inventing a separate wrapper
header file, allowing the pragma to be tightly scoped to just
the Python headers and not other stuff we have laying about in
plpython.h. I applied the same technique to plperl for the same
reason: the original patch suppressed warnings for a good deal
of our own code, not only the Perl headers.
Like the previous commit, back-patch to supported branches.
Peter Eisentraut and Tom Lane
Discussion: https://postgr.es/m/ae523163-6d2a-4b81-a875-832e48dec502@eisentraut.org
This is necessary when spgcanreturn() is invoked on a partitioned
index, and the failure might be reachable in other scenarios as
well. The rest of what spgGetCache() does is perfectly sensible
for a partitioned index, so we should allow it to go through.
I think the main takeaway from this is that we lack sufficient test
coverage for non-btree partitioned indexes. Therefore, I added
simple test cases for brin and gin as well as spgist (hash and
gist AMs were covered already in indexing.sql).
Per bug #18256 from Alexander Lakhin. Although the known test case
only fails since v16 (3c569049b), I've got no faith at all that there
aren't other ways to reach this problem; so back-patch to all
supported branches.
Discussion: https://postgr.es/m/18256-0b0e1b6e4a620f1b@postgresql.org
The example for dropping an option was incorrectly quoting the
option key thus making it a value turning the command into an
unqualified ADD operation. The result of dropping became adding
a new key/value pair instead:
d=# alter foreign data wrapper f options (drop 'b');
ALTER FOREIGN DATA WRAPPER
d=# select fdwoptions from pg_foreign_data_wrapper where fdwname='f';
fdwoptions
------------
{drop=b}
(1 row)
This has been incorrect for a long time so backpatch to all
supported branches.
Author: Tim <tim.needham2@gmail.com>
Discussion: https://postgr.es/m/170292280173.1876505.5204623074024041738@wrigleys.postgresql.org
This function reads directly a page from a relation, relying on
index_open() to open the index to read from. Unfortunately, this would
crash when using partitioned indexes, as these can be opened with
index_open() but they have no physical pages.
Alexander has fixed the module, while I have written the test.
Author: Alexander Lakhin, Michael Paquier
Discussion: https://postgr.es/m/18246-f4d9ff7cb3af77e6@postgresql.org
Backpatch-through: 12
As coded, the function relied on index_open() when opening an index
relation, allowing partitioned indexes to be processed by
pgstathashindex(). This was leading to a "could not open file" error
because partitioned indexes have no physical files, or to a crash with
an assertion failure (like on HEAD).
This issue is fixed by applying the same checks as the other stat
functions for indexes, with a lookup at both RELKIND_INDEX and the index
AM expected.
Author: Alexander Lakhin
Discussion: https://postgr.es/m/18246-f4d9ff7cb3af77e6@postgresql.org
Backpatch-through: 12
We didn't explain this clearly until somewhere deep in the
"Extending SQL" chapter, but really it ought to be mentioned
in the introductory material too.
Discussion: https://postgr.es/m/4097442.1694967650@sss.pgh.pa.us
In v16 and up (since commit afbfc0298), large object ownership
checking has been broken because object_ownercheck() didn't take care
of the discrepancy between our object-address representation of large
objects (classId == LargeObjectRelationId) and the catalog where their
ownership info is actually stored (LargeObjectMetadataRelationId).
This resulted in failures such as "unrecognized class ID: 2613"
when trying to update blob properties as a non-superuser.
Poking around for related bugs, I found that AlterObjectOwner_internal
would pass the wrong classId to the PostAlterHook in the no-op code
path where the large object already has the desired owner. Also,
recordExtObjInitPriv checked for the wrong classId; that bug is only
latent because the stanza is dead code anyway, but as long as we're
carrying it around it should be less wrong. These bugs are quite old.
In HEAD, we can reduce the scope for future bugs of this ilk by
changing AlterObjectOwner_internal's API to let the translation happen
inside that function, rather than requiring callers to know about it.
A more bulletproof fix, perhaps, would be to start using
LargeObjectMetadataRelationId as the dependency and object-address
classId for blobs. However that has substantial risk of breaking
third-party code; even within our own code, it'd create hassles
for pg_dump which would have to cope with a version-dependent
representation. For now, keep the status quo.
Discussion: https://postgr.es/m/2650449.1702497209@sss.pgh.pa.us
Dead tuples are ignored and are not marked as dead during recovery, as
it can lead to MVCC issues on a standby because its xmin may not match
with the primary. This information is tracked by a field called
"xactStartedInRecovery" in the transaction state data, switched on when
starting a transaction in recovery.
Unfortunately, this information was not correctly tracked when starting
a subtransaction, because the transaction state used for the
subtransaction did not update "xactStartedInRecovery" based on the state
of its parent. This would cause index scans done in subtransactions to
return inconsistent data, depending on how the xmin of the primary
and/or the standby evolved.
This is broken since the introduction of hot standby in efc16ea520, so
backpatch all the way down.
Author: Fei Changhong
Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/tencent_C4D907A5093C071A029712E73B43C6512706@qq.com
Backpatch-through: 12
OpenSSL will sometimes return SSL_ERROR_SYSCALL without having set
errno; this is apparently a reflection of recv(2)'s habit of not
setting errno when reporting EOF. Ensure that we treat such cases
the same as read EOF. Previously, we'd frequently report them like
"could not accept SSL connection: Success" which is confusing, or
worse report them with an unrelated errno left over from some
previous syscall.
To fix, ensure that errno is zeroed immediately before the call,
and report its value only when it's not zero afterwards; otherwise
report EOF.
For consistency, I've applied the same coding pattern in libpq's
pqsecure_raw_read(). Bare recv(2) shouldn't really return -1 without
setting errno, but in case it does we might as well cope.
Per report from Andres Freund. Back-patch to all supported versions.
Discussion: https://postgr.es/m/20231208181451.deqnflwxqoehhxpe@awork3.anarazel.de
The apply worker needs to update the state of the subscription tables to
'READY' during the synchronization phase which requires locking the
corresponding subscription. The apply worker also waits for the
subscription tables to reach the 'SYNCDONE' state after holding the locks
on the subscription and the wait is done using WaitLatch. The 'SYNCDONE'
state is changed by tablesync workers again by locking the corresponding
subscription. Both the state updates use AccessShareLock mode to lock the
subscription, so they can't block each other. However, a backend can
simultaneously try to acquire a lock on the same subscription using
AccessExclusiveLock mode to alter the subscription. Now, the backend's
wait on a lock can sneak in between the apply worker and table sync worker
causing deadlock.
In other words, apply_worker waits for tablesync worker which waits for
backend, and backend waits for apply worker. This is not detected by the
deadlock detector because apply worker uses WaitLatch.
The fix is to release existing locks in apply worker before it starts to
wait for tablesync worker to change the state.
Reported-by: Tomas Vondra
Author: Shlok Kyal
Reviewed-by: Amit Kapila, Peter Smith
Backpatch-through: 12
Discussion: https://postgr.es/m/d291bb50-12c4-e8af-2af2-7bb9bb4d8e3e@enterprisedb.com
Commit 5a991ef869 accidentally reversed the order of the tuples
and fields parameters, making the error message incorrectly refer
to 3 tuples with 1 field when IDENTIFY_SYSTEM returns 1 tuple and
3 or 4 fields. Fix by changing the order of the parameters. This
also adds a comment describing why we check for < 3 when postgres
since 9.4 has been sending 4 fields.
Backpatch all the way since the bug is almost a decade old.
Author: Tomonari Katsumata <t.katsumata1122@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Bug: #18224
Backpatch-through: v12
The logic to keep the libpq command queue in sync with queries that have
been processed had a bug when errors were returned for reasons other
than problems in queries -- for example, when a connection is lost. We
incorrectly consumed an element from the command queue every time, but
this is wrong and can lead to the queue becoming empty ahead of time,
leading to later malfunction: PQgetResult would return nothing,
potentially causing the calling application to enter a busy loop.
Fix by making the SYNC queue element a barrier that can only be consumed
when a SYNC message is received.
Backpatch to 14.
Reported by: Иван Трофимов (Ivan Trofimov) <i.trofimow@yandex.ru>
Discussion: https://postgr.es/m/17948-fcace7557e449957@postgresql.org
It draws an unnecessary error in builds compiled without thread support.
Added by commit 038f586d5f, which was backpatched to 14; though in
branch master we no longer support such builds, there's no reason to
have this there, so remove it in all branches since 14.
Reported-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/ZW2G9Ix4nBKLcSSO@paquier.xyz
The wording changed here comes from 991bfe11d2, when the only way to
trigger a promotion was with a trigger file. There are more options to
achieve this operation these days, like the SQL function pg_promote() or
the command `pg_ctl promote`, so it is confusing to assume that only a
trigger file is able to do the work.
Note also that promote_trigger_file has been removed as of cd4329d939
in 16~.
Author: Shinya Kato
Discussion: https://postgr.es/m/201b08ea29aa61f96162080e75be503c@oss.nttdata.com
Backpatch-through: 12
When creating a partitioned index, the partition key must be a subset
of the index's columns. But this currently doesn't check that the
collations between the partition key and the index definition match.
So you can construct a unique index that fails to enforce uniqueness.
(This would most likely involve a nondeterministic collation, so it
would have to be crafted explicitly and is not something that would
just happen by accident.)
This patch adds the required collation check. As a result, any
previously allowed unique index that has a collation mismatch would no
longer be allowed to be created.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/3327cb54-f7f1-413b-8fdb-7a9dceebb938%40eisentraut.org
We should have done it this way all along, but we accidentally got
away with using the wrong BIO field up until OpenSSL 3.2. There,
the library's BIO routines that we rely on use the "data" field
for their own purposes, and our conflicting use causes assorted
weird behaviors up to and including core dumps when SSL connections
are attempted. Switch to using the approved field for the purpose,
i.e. app_data.
While at it, remove our configure probes for BIO_get_data as well
as the fallback implementation. BIO_{get,set}_app_data have been
there since long before any OpenSSL version that we still support,
even in the back branches.
Also, update src/test/ssl/t/001_ssltests.pl to allow for a minor
change in an error message spelling that evidently came in with 3.2.
Tristan Partin and Bo Andreson. Back-patch to all supported branches.
Discussion: https://postgr.es/m/CAN55FZ1eDDYsYaL7mv+oSLUij2h_u6hvD4Qmv-7PK7jkji0uyQ@mail.gmail.com
If the tuple being updated is not visible to the crosscheck snapshot,
we return TM_Updated but the assertions would not hold in that case.
Move them to before the cross-check.
Fixes bug #17893. Backpatch to all supported versions.
Author: Alexander Lakhin
Backpatch-through: 12
Discussion: https://www.postgresql.org/message-id/17893-35847009eec517b5%40postgresql.org
The libpq code in charge of creating per-connection SSL objects was
prone to a race condition when loading the custom BIO methods needed by
my_SSL_set_fd(). As BIO methods are stored as a static variable, the
initialization of a connection could fail because it could be possible
to have one thread refer to my_bio_methods while it is being manipulated
by a second concurrent thread.
This error has been introduced by 8bb14cdd33, that has removed
ssl_config_mutex around the call of my_SSL_set_fd(), that itself sets
the custom BIO methods used in libpq. Like previously, the BIO method
initialization is now protected by the existing ssl_config_mutex, itself
initialized earlier for WIN32.
While on it, document that my_bio_methods is protected by
ssl_config_mutex, as this can be easy to miss.
Reported-by: Willi Mann
Author: Willi Mann, Michael Paquier
Discussion: https://postgr.es/m/e77abc4c-4d03-4058-a9d7-ef0035657e04@celonis.com
Backpatch-through: 12
When using GSSAPI encryption in non-blocking mode, libpq sometimes
failed with "GSSAPI caller failed to retransmit all data needing
to be retried". The cause is that pqPutMsgEnd rounds its transmit
request down to an even multiple of 8K, and sometimes that can lead
to not requesting a write of data that was requested to be written
(but reported as not written) earlier. That can upset pg_GSS_write's
logic for dealing with not-yet-written data, since it's possible
the data in question had already been incorporated into an encrypted
packet that we weren't able to send during the previous call.
We could fix this with a one-or-two-line hack to disable pqPutMsgEnd's
round-down behavior, but that seems like making the caller work around
a behavior that pg_GSS_write shouldn't expose in this way. Instead,
adjust pg_GSS_write to never report a partial write: it either
reports a complete write, or reflects the failure of the lower-level
pqsecure_raw_write call. The requirement still exists for the caller
to present at least as much data as on the previous call, but with
the caller-visible write start point not moving there is no temptation
for it to present less. We lose some ability to reclaim buffer space
early, but I doubt that that will make much difference in practice.
This also gets rid of a rather dubious assumption that "any
interesting failure condition (from pqsecure_raw_write) will recur
on the next try". We've not seen failure reports traceable to that,
but I've never trusted it particularly and am glad to remove it.
Make the same adjustments to the equivalent backend routine
be_gssapi_write(). It is probable that there's no bug on the backend
side, since we don't have a notion of nonblock mode there; but we
should keep the logic the same to ease future maintenance.
Per bug #18210 from Lars Kanis. Back-patch to all supported branches.
Discussion: https://postgr.es/m/18210-4c6d0b14627f2eb8@postgresql.org
If an error is thrown after calling CreateWaitEventSet(), the memory
of a WaitEventSet is free'd as it's allocated in the short-lived
memory context, but the file descriptor (on epoll- or kqueue-based
systems) or handles (on Windows) that it contains are leaked.
Use PG_TRY-FINALLY to ensure it gets freed. (On master, I will apply a
better fix, using ResourceOwners to track the WaitEventSet, but that's
not backpatchable.)
The added test doesn't check for leaking resources, so it passed even
before this commit. But at least it covers the code path.
In the passing, fix misleading comment on what the 'nevents' argument
to WaitEventSetWait means.
Report by Alexander Lakhin, analysis and suggestion for the fix by Tom
Lane. Fixes bug #17828. Backpatch to v14 where async execution was
introduced, but master gets a different fix.
Discussion: https://www.postgresql.org/message-id/17828-122da8cba23236be@postgresql.org
Discussion: https://www.postgresql.org/message-id/472235.1678387869@sss.pgh.pa.us
Michael Paquier
Andres Freund
Heikki Linnakangas
Daniel Gustafsson
Alvaro Herrera
Tom Lane
Magnus Hagander
Tatsuo Ishii
Alexander Korotkov
Bruce Momjian
Amit Kapila
Peter Eisentraut