Ensure shared memory functions handle NULL parameters correctly

expected/repmgr_extension.out

@@ -38,6 +38,12 @@ SELECT repmgr.am_bdr_failover_handler(-1);
  
 (1 row)
 
+SELECT repmgr.am_bdr_failover_handler(NULL);
+ am_bdr_failover_handler 
+-------------------------
+ 
+(1 row)
+
 SELECT repmgr.get_new_primary();
  get_new_primary 
 -----------------
@@ -56,18 +62,60 @@ SELECT repmgr.notify_follow_primary(-1);
  
 (1 row)
 
+SELECT repmgr.notify_follow_primary(NULL);
+ notify_follow_primary 
+-----------------------
+ 
+(1 row)
+
 SELECT repmgr.other_node_is_candidate(-1,-1);
  other_node_is_candidate 
 -------------------------
  
 (1 row)
 
+SELECT repmgr.other_node_is_candidate(-1,NULL);
+ other_node_is_candidate 
+-------------------------
+ 
+(1 row)
+
+SELECT repmgr.other_node_is_candidate(NULL,-1);
+ other_node_is_candidate 
+-------------------------
+ 
+(1 row)
+
+SELECT repmgr.other_node_is_candidate(NULL,NULL);
+ other_node_is_candidate 
+-------------------------
+ 
+(1 row)
+
 SELECT repmgr.request_vote(-1,-1);
  request_vote 
 --------------
  
 (1 row)
 
+SELECT repmgr.request_vote(-1,NULL);
+ request_vote 
+--------------
+ 
+(1 row)
+
+SELECT repmgr.request_vote(NULL,-1);
+ request_vote 
+--------------
+ 
+(1 row)
+
+SELECT repmgr.request_vote(NULL,NULL);
+ request_vote 
+--------------
+ 
+(1 row)
+
 SELECT repmgr.reset_voting_status();
  reset_voting_status 
 ---------------------
@@ -80,6 +128,12 @@ SELECT repmgr.set_local_node_id(-1);
  
 (1 row)
 
+SELECT repmgr.set_local_node_id(NULL);
+ set_local_node_id 
+-------------------
+ 
+(1 row)
+
 SELECT repmgr.set_voting_status_initiated();
  set_voting_status_initiated 
 -----------------------------

repmgr.c

@@ -227,11 +227,16 @@ repmgr_shmem_startup(void)
 Datum
 set_local_node_id(PG_FUNCTION_ARGS)
 {
-	int			local_node_id = PG_GETARG_INT32(0);
+	int			local_node_id = UNKNOWN_NODE_ID;
 
 	if (!shared_state)
 		PG_RETURN_NULL();
 
+	if (PG_ARGISNULL(0))
+		PG_RETURN_NULL();
+
+	local_node_id = PG_GETARG_INT32(0);
+
 	LWLockAcquire(shared_state->lock, LW_EXCLUSIVE);
 
 	/* only set local_node_id once, as it should never change */
@@ -301,14 +306,20 @@ request_vote(PG_FUNCTION_ARGS)
 #endif
 
 	/* node_id used for logging purposes */
-	int			requesting_node_id = PG_GETARG_INT32(0);
+	int			requesting_node_id = UNKNOWN_NODE_ID;
-	int			current_electoral_term = PG_GETARG_INT32(1);
+	int			current_electoral_term = UNKNOWN_NODE_ID;
 
 	int			ret;
 
 	if (!shared_state)
 		PG_RETURN_NULL();
 
+	if (PG_ARGISNULL(0) || PG_ARGISNULL(1))
+		PG_RETURN_NULL();
+
+	requesting_node_id = PG_GETARG_INT32(0);
+	current_electoral_term = PG_GETARG_INT32(1);
+
 	LWLockAcquire(shared_state->lock, LW_SHARED);
 
 	/* only do something if local_node_id is initialised */
@@ -453,12 +464,19 @@ Datum
 other_node_is_candidate(PG_FUNCTION_ARGS)
 {
 #ifndef BDR_ONLY
-	int			requesting_node_id = PG_GETARG_INT32(0);
+
-	int			electoral_term = PG_GETARG_INT32(1);
+	int			requesting_node_id = UNKNOWN_NODE_ID;
+	int			electoral_term = UNKNOWN_NODE_ID;
 
 	if (!shared_state)
 		PG_RETURN_NULL();
 
+	if (PG_ARGISNULL(0) || PG_ARGISNULL(1))
+		PG_RETURN_NULL();
+
+	requesting_node_id = PG_GETARG_INT32(0);
+	electoral_term = PG_GETARG_INT32(1);
+
 	LWLockAcquire(shared_state->lock, LW_SHARED);
 
 	/* only do something if local_node_id is initialised */
@@ -493,11 +511,16 @@ Datum
 notify_follow_primary(PG_FUNCTION_ARGS)
 {
 #ifndef BDR_ONLY
-	int			primary_node_id = PG_GETARG_INT32(0);
+	int			primary_node_id = UNKNOWN_NODE_ID;
 
 	if (!shared_state)
 		PG_RETURN_NULL();
 
+	if (PG_ARGISNULL(0))
+		PG_RETURN_NULL();
+
+	primary_node_id = PG_GETARG_INT32(0);
+
 	LWLockAcquire(shared_state->lock, LW_SHARED);
 
 	/* only do something if local_node_id is initialised */
@@ -536,6 +559,10 @@ get_new_primary(PG_FUNCTION_ARGS)
 
 	LWLockRelease(shared_state->lock);
 #endif
+
+	if (new_primary_node_id == UNKNOWN_NODE_ID)
+		PG_RETURN_NULL();
+
 	PG_RETURN_INT32(new_primary_node_id);
 }
 
@@ -569,12 +596,17 @@ reset_voting_status(PG_FUNCTION_ARGS)
 Datum
 am_bdr_failover_handler(PG_FUNCTION_ARGS)
 {
-	int			node_id = PG_GETARG_INT32(0);
+	int			node_id = UNKNOWN_NODE_ID;
 	bool		am_handler = false;
 
 	if (!shared_state)
 		PG_RETURN_NULL();
 
+	if (PG_ARGISNULL(0))
+		PG_RETURN_NULL();
+
+	node_id = PG_GETARG_INT32(0);
+
 	LWLockAcquire(shared_state->lock, LW_SHARED);
 
 	if (shared_state->bdr_failover_handler == UNKNOWN_NODE_ID)

sql/repmgr_extension.sql

@@ -18,13 +18,22 @@ SELECT * FROM repmgr.show_nodes;
 
 -- functions
 SELECT repmgr.am_bdr_failover_handler(-1);
+SELECT repmgr.am_bdr_failover_handler(NULL);
 SELECT repmgr.get_new_primary();
 SELECT repmgr.get_voting_status();
 SELECT repmgr.notify_follow_primary(-1);
+SELECT repmgr.notify_follow_primary(NULL);
 SELECT repmgr.other_node_is_candidate(-1,-1);
+SELECT repmgr.other_node_is_candidate(-1,NULL);
+SELECT repmgr.other_node_is_candidate(NULL,-1);
+SELECT repmgr.other_node_is_candidate(NULL,NULL);
 SELECT repmgr.request_vote(-1,-1);
+SELECT repmgr.request_vote(-1,NULL);
+SELECT repmgr.request_vote(NULL,-1);
+SELECT repmgr.request_vote(NULL,NULL);
 SELECT repmgr.reset_voting_status();
 SELECT repmgr.set_local_node_id(-1);
+SELECT repmgr.set_local_node_id(NULL);
 SELECT repmgr.set_voting_status_initiated();
 SELECT repmgr.standby_get_last_updated();
 SELECT repmgr.standby_set_last_updated();