Improve CREATE SUBSCRIPTION option parsing

When creating a subscription with slot_name = NONE, we failed to check
that also create_slot = false and enabled = false were set.  This
created an invalid subscription and could later lead to a crash if a
NULL slot name was accessed.  Add more checks around that for
robustness.
Reported-by: tushar <tushar.ahuja@enterprisedb.com>

src/backend/commands/subscriptioncmds.c

@@ -168,7 +168,9 @@ parse_subscription_options(List *options, bool *connect, bool *enabled_given,
 									 false, 0, false);
 		}
 		else
-			elog(ERROR, "unrecognized option: %s", defel->defname);
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("unrecognized subscription parameter: %s", defel->defname)));
 	}
 
 	/*
@@ -214,6 +216,16 @@ parse_subscription_options(List *options, bool *connect, bool *enabled_given,
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("slot_name = NONE and create_slot = true are mutually exclusive options")));
+
+		if (enabled && !*enabled_given && *enabled)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("subscription with slot_name = NONE must also set enabled = false")));
+
+		if (create_slot && !create_slot_given && *create_slot)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("subscription with slot_name = NONE must also set create_slot = false")));
 	}
 }
 

src/backend/replication/logical/worker.c

@@ -1552,6 +1552,15 @@ ApplyWorkerMain(Datum main_arg)
 
 		myslotname = MySubscription->slotname;
 
+		/*
+		 * This shouldn't happen if the subscription is enabled, but guard
+		 * against DDL bugs or manual catalog changes.  (libpqwalreceiver
+		 * will crash if slot is NULL.
+		 */
+		if (!myslotname)
+			ereport(ERROR,
+					(errmsg("subscription has no replication slot set")));
+
 		/* Setup replication origin tracking. */
 		StartTransactionCommand();
 		snprintf(originname, sizeof(originname), "pg_%u", MySubscription->oid);

src/test/regress/expected/subscription.out

@@ -56,6 +56,12 @@ CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpu
 ERROR:  slot_name = NONE and enabled = true are mutually exclusive options
 CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, create_slot = true);
 ERROR:  slot_name = NONE and create_slot = true are mutually exclusive options
+CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE);
+ERROR:  subscription with slot_name = NONE must also set enabled = false
+CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, enabled = false);
+ERROR:  subscription with slot_name = NONE must also set create_slot = false
+CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, create_slot = false);
+ERROR:  subscription with slot_name = NONE must also set enabled = false
 -- ok - with slot_name = NONE
 CREATE SUBSCRIPTION testsub3 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, connect = false);
 WARNING:  tables were not subscribed, you will have to run ALTER SUBSCRIPTION ... REFRESH PUBLICATION to subscribe the tables
@@ -82,6 +88,8 @@ ALTER SUBSCRIPTION testsub SET (slot_name = 'newname');
 -- fail
 ALTER SUBSCRIPTION doesnotexist CONNECTION 'dbname=doesnotexist2';
 ERROR:  subscription "doesnotexist" does not exist
+ALTER SUBSCRIPTION testsub SET (create_slot = false);
+ERROR:  unrecognized subscription parameter: create_slot
 \dRs+
                                               List of subscriptions
   Name   |           Owner           | Enabled |     Publication     | Synchronous commit |       Conninfo       

src/test/regress/sql/subscription.sql

@@ -44,6 +44,9 @@ CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpu
 CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (connect = false, create_slot = true);
 CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, enabled = true);
 CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, create_slot = true);
+CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE);
+CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, enabled = false);
+CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, create_slot = false);
 
 -- ok - with slot_name = NONE
 CREATE SUBSCRIPTION testsub3 CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (slot_name = NONE, connect = false);
@@ -64,6 +67,7 @@ ALTER SUBSCRIPTION testsub SET (slot_name = 'newname');
 
 -- fail
 ALTER SUBSCRIPTION doesnotexist CONNECTION 'dbname=doesnotexist2';
+ALTER SUBSCRIPTION testsub SET (create_slot = false);
 
 \dRs+