Fix walsender error cleanup code

In commit 850196b610 I (Álvaro) failed to handle the case of walsender
shutting down on an error before setting up its 'xlogreader' pointer;
the error handling code dereferences the pointer, causing a crash.
Fix by testing the pointer before trying to dereference it.

Kyotaro authored the code fix; I adopted Nathan's test case to be used
by the TAP tests and added the necessary PostgresNode change.

Reported-by: Nathan Bossart <bossartn@amazon.com>
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/C04FC24E-903D-4423-B312-6910E4D846E5@amazon.com
This commit is contained in:
Alvaro Herrera 2020-05-15 19:59:29 -04:00
parent 14a9101091
commit 1d3743023e
No known key found for this signature in database
GPG Key ID: 1C20ACB9D5C564AE
3 changed files with 27 additions and 5 deletions

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@ -315,7 +315,7 @@ WalSndErrorCleanup(void)
ConditionVariableCancelSleep();
pgstat_report_wait_end();
if (xlogreader->seg.ws_file >= 0)
if (xlogreader != NULL && xlogreader->seg.ws_file >= 0)
wal_segment_close(xlogreader);
if (MyReplicationSlot != NULL)

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@ -1386,6 +1386,12 @@ the B<timed_out> parameter is also given.
If B<timeout> is set and this parameter is given, the scalar it references
is set to true if the psql call times out.
=item replication => B<value>
If set, add B<replication=value> to the conninfo string.
Passing the literal value C<database> results in a logical replication
connection.
=item extra_params => ['--single-transaction']
If given, it must be an array reference containing additional parameters to B<psql>.
@ -1414,10 +1420,17 @@ sub psql
my $stdout = $params{stdout};
my $stderr = $params{stderr};
my $replication = $params{replication};
my $timeout = undef;
my $timeout_exception = 'psql timed out';
my @psql_params =
('psql', '-XAtq', '-d', $self->connstr($dbname), '-f', '-');
my @psql_params = (
'psql',
'-XAtq',
'-d',
$self->connstr($dbname)
. (defined $replication ? " replication=$replication" : ""),
'-f',
'-');
# If the caller wants an array and hasn't passed stdout/stderr
# references, allocate temporary ones to capture them so we

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@ -7,7 +7,7 @@ use strict;
use warnings;
use PostgresNode;
use TestLib;
use Test::More tests => 12;
use Test::More tests => 13;
use Config;
# Initialize master node
@ -27,12 +27,21 @@ $node_master->safe_psql('postgres',
qq[SELECT pg_create_logical_replication_slot('test_slot', 'test_decoding');]
);
# Cover walsender error shutdown code
my ($result, $stdout, $stderr) = $node_master->psql(
'template1',
qq[START_REPLICATION SLOT test_slot LOGICAL 0/0],
replication => 'database');
ok( $stderr =~
m/replication slot "test_slot" was not created in this database/,
"Logical decoding correctly fails to start");
$node_master->safe_psql('postgres',
qq[INSERT INTO decoding_test(x,y) SELECT s, s::text FROM generate_series(1,10) s;]
);
# Basic decoding works
my ($result) = $node_master->safe_psql('postgres',
$result = $node_master->safe_psql('postgres',
qq[SELECT pg_logical_slot_get_changes('test_slot', NULL, NULL);]);
is(scalar(my @foobar = split /^/m, $result),
12, 'Decoding produced 12 rows inc BEGIN/COMMIT');