Add test for session_preload_libraries and parameter permissions checks.

We weren't exercising the session_preload_libraries option in any
meaningful way.  auto_explain is a good testbed for doing so, since
it's one of the primary use-cases for session_preload_libraries.
Hence, adjust its TAP test to load the library via
session_preload_libraries not shared_preload_libraries.  While at it,
feed test-specific settings to the backend via PGOPTIONS rather than
tediously rewriting postgresql.conf.

Also, since auto_explain has some PGC_SUSET parameters, we can use it
to provide a test case for the permissions-checking bug just fixed
by commit b35617de3.

Back-patch to v15 so that we have coverage for the permissions issue
in that branch too.  To do that, I back-patched the refactoring
recently done by commit 550bc0a6c.

Dagfinn Ilmari Mannsåker and Tom Lane

Discussion: https://postgr.es/m/CABwTF4VEpwTHhRQ+q5MiC5ucngN-whN-PdcKeufX7eLSoAfbZA@mail.gmail.com

contrib/auto_explain/t/001_auto_explain.pl

@@ -8,50 +8,141 @@ use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
+# Runs the specified query and returns the emitted server log.
+# params is an optional hash mapping GUC names to values;
+# any such settings are transmitted to the backend via PGOPTIONS.
+sub query_log
+{
+	my ($node, $sql, $params) = @_;
+	$params ||= {};
+
+	local $ENV{PGOPTIONS} = join " ",
+	  map { "-c $_=$params->{$_}" } keys %$params;
+
+	my $log    = $node->logfile();
+	my $offset = -s $log;
+
+	$node->safe_psql("postgres", $sql);
+
+	return slurp_file($log, $offset);
+}
+
 my $node = PostgreSQL::Test::Cluster->new('main');
 $node->init;
 $node->append_conf('postgresql.conf',
-	"shared_preload_libraries = 'auto_explain'");
+	"session_preload_libraries = 'auto_explain'");
 $node->append_conf('postgresql.conf', "auto_explain.log_min_duration = 0");
 $node->append_conf('postgresql.conf', "auto_explain.log_analyze = on");
 $node->start;
 
-# run a couple of queries
-$node->safe_psql("postgres", "SELECT * FROM pg_class;");
-$node->safe_psql("postgres",
-	"SELECT * FROM pg_proc WHERE proname = 'int4pl';");
+# Simple query.
+my $log_contents = query_log($node, "SELECT * FROM pg_class;");
 
-# emit some json too
-$node->append_conf('postgresql.conf', "auto_explain.log_format = json");
-$node->reload;
-$node->safe_psql("postgres", "SELECT * FROM pg_proc;");
-$node->safe_psql("postgres",
-	"SELECT * FROM pg_class WHERE relname = 'pg_class';");
-
-$node->stop('fast');
-
-my $log = $node->logfile();
+like(
+	$log_contents,
+	qr/Query Text: SELECT \* FROM pg_class;/,
+	"query text logged, text mode");
 
-my $log_contents = slurp_file($log);
+unlike(
+	$log_contents,
+	qr/Query Parameters:/,
+	"no query parameters logged when none, text mode");
 
 like(
 	$log_contents,
 	qr/Seq Scan on pg_class/,
 	"sequential scan logged, text mode");
 
+# Prepared query.
+$log_contents = query_log($node,
+	q{PREPARE get_proc(name) AS SELECT * FROM pg_proc WHERE proname = $1; EXECUTE get_proc('int4pl');}
+);
+
+like(
+	$log_contents,
+	qr/Query Text: PREPARE get_proc\(name\) AS SELECT \* FROM pg_proc WHERE proname = \$1;/,
+	"prepared query text logged, text mode");
+
 like(
 	$log_contents,
 	qr/Index Scan using pg_proc_proname_args_nsp_index on pg_proc/,
 	"index scan logged, text mode");
 
+
+# JSON format.
+$log_contents = query_log(
+	$node,
+	"SELECT * FROM pg_class;",
+	{ "auto_explain.log_format" => "json" });
+
+like(
+	$log_contents,
+	qr/"Query Text": "SELECT \* FROM pg_class;"/,
+	"query text logged, json mode");
+
+unlike(
+	$log_contents,
+	qr/"Query Parameters":/,
+	"query parameters not logged when none, json mode");
+
 like(
 	$log_contents,
-	qr/"Node Type": "Seq Scan"[^}]*"Relation Name": "pg_proc"/s,
+	qr/"Node Type": "Seq Scan"[^}]*"Relation Name": "pg_class"/s,
 	"sequential scan logged, json mode");
 
+# Prepared query in JSON format.
+$log_contents = query_log(
+	$node,
+	q{PREPARE get_class(name) AS SELECT * FROM pg_class WHERE relname = $1; EXECUTE get_class('pg_class');},
+	{ "auto_explain.log_format" => "json" });
+
+like(
+	$log_contents,
+	qr/"Query Text": "PREPARE get_class\(name\) AS SELECT \* FROM pg_class WHERE relname = \$1;"/,
+	"prepared query text logged, json mode");
+
 like(
 	$log_contents,
 	qr/"Node Type": "Index Scan"[^}]*"Index Name": "pg_class_relname_nsp_index"/s,
 	"index scan logged, json mode");
 
+# Check that PGC_SUSET parameters can be set by non-superuser if granted,
+# otherwise not
+
+$node->safe_psql(
+	"postgres", q{
+CREATE USER regress_user1;
+GRANT SET ON PARAMETER auto_explain.log_format TO regress_user1;
+});
+
+$ENV{PGUSER} = "regress_user1";
+
+$log_contents = query_log(
+	$node,
+	"SELECT * FROM pg_database;",
+	{ "auto_explain.log_format" => "json" });
+
+like(
+	$log_contents,
+	qr/"Query Text": "SELECT \* FROM pg_database;"/,
+	"query text logged, json mode selected by non-superuser");
+
+$log_contents = query_log(
+	$node,
+	"SELECT * FROM pg_database;",
+	{ "auto_explain.log_level" => "log" });
+
+like(
+	$log_contents,
+	qr/WARNING:  permission denied to set parameter "auto_explain\.log_level"/,
+	"permission failure logged");
+
+$ENV{PGUSER} = undef;
+
+$node->safe_psql(
+	"postgres", q{
+REVOKE SET ON PARAMETER auto_explain.log_format FROM regress_user1;
+DROP USER regress_user1;
+});
+
 done_testing();