Fix Semmle errors (#4636)

Co-authored-by: Halil Ozan Akgül <hozanakgul@gmail.com>

src/backend/distributed/commands/alter_table.c

@@ -1418,7 +1418,15 @@ CheckAlterDistributedTableConversionParameters(TableConversionState *con)
 
 		Var *colocateWithPartKey = DistPartitionKey(colocateWithTableOid);
 
-		if (con->distributionColumn &&
+		if (colocateWithPartKey == NULL)
+		{
+			/* this should never happen */
+			ereport(ERROR, (errmsg("cannot colocate %s with %s because %s doesn't have a "
+								   "distribution column",
+								   con->relationName, con->colocateWith,
+								   con->colocateWith)));
+		}
+		else if (con->distributionColumn &&
 				 colocateWithPartKey->vartype != con->distributionKey->vartype)
 		{
 			ereport(ERROR, (errmsg("cannot colocate with %s and change distribution "

src/backend/distributed/commands/cascade_table_operation_for_connected_relations.c

@@ -68,6 +68,13 @@ CascadeOperationForConnectedRelations(Oid relationId, LOCKMODE lockMode,
 	InvalidateForeignKeyGraph();
 
 	List *fKeyConnectedRelationIdList = GetForeignKeyConnectedRelationIdList(relationId);
+
+	/* early exit if there are no connected relations */
+	if (fKeyConnectedRelationIdList == NIL)
+	{
+		return;
+	}
+
 	LockRelationsWithLockMode(fKeyConnectedRelationIdList, lockMode);
 
 	/*

src/backend/distributed/commands/index_pg_source.c

@@ -181,13 +181,13 @@ ChooseIndexColumnNames(List *indexElems)
 			{
 				break;          /* found nonconflicting name */
 			}
-			sprintf(nbuf, "%d", i);
+			sprintf(nbuf, "%d", i); /* lgtm[cpp/banned-api-usage-required-any] */
 
 			/* Ensure generated names are shorter than NAMEDATALEN */
 			nlen = pg_mbcliplen(origname, strlen(origname),
 								NAMEDATALEN - 1 - strlen(nbuf));
-			memcpy(buf, origname, nlen);
-			strcpy(buf + nlen, nbuf);
+			memcpy(buf, origname, nlen); /* lgtm[cpp/banned-api-usage-required-any] */
+			strcpy(buf + nlen, nbuf); /* lgtm[cpp/banned-api-usage-required-any] */
 			curname = buf;
 		}
 

src/backend/distributed/commands/utility_hook.c

@@ -682,7 +682,7 @@ ProcessUtilityInternal(PlannedStmt *pstmt,
 		 * Ensure value is valid, we can't do some checks during CREATE
 		 * EXTENSION. This is important to register some invalidation callbacks.
 		 */
-		CitusHasBeenLoaded();
+		CitusHasBeenLoaded(); /* lgtm[cpp/return-value-ignored] */
 	}
 }
 

src/backend/distributed/metadata/metadata_cache.c

@@ -849,7 +849,7 @@ InitializeTableCacheEntry(int64 shardId)
 	Oid relationId = LookupShardRelationFromCatalog(shardId, missingOk);
 
 	/* trigger building the cache for the shard id */
-	GetCitusTableCacheEntry(relationId);
+	GetCitusTableCacheEntry(relationId); /* lgtm[cpp/return-value-ignored] */
 }
 
 

src/backend/distributed/operations/citus_tools.c

@@ -509,7 +509,13 @@ ExecuteRemoteQueryOrCommand(char *nodeName, uint32 nodePort, char *queryString,
 		return false;
 	}
 
-	SendRemoteCommand(connection, queryString);
+	if (!SendRemoteCommand(connection, queryString))
+	{
+		appendStringInfo(queryResultString, "failed to send query to %s:%d", nodeName,
+						 (int) nodePort);
+		return false;
+	}
+
 	PGresult *queryResult = GetRemoteCommandResult(connection, raiseInterrupts);
 	bool success = EvaluateQueryResult(connection, queryResult, queryResultString);
 

src/backend/distributed/planner/local_distributed_join_planner.c

@@ -237,7 +237,7 @@ ResultRTEIdentity(Query *query)
 	int resultRTEIdentity = INVALID_RTE_IDENTITY;
 	if (IsModifyCommand(query))
 	{
-		RangeTblEntry *resultRTE = ExtractResultRelationRTE(query);
+		RangeTblEntry *resultRTE = ExtractResultRelationRTEOrError(query);
 		resultRTEIdentity = GetRTEIdentity(resultRTE);
 	}
 	return resultRTEIdentity;

src/backend/distributed/test/run_from_same_connection.c

@@ -200,10 +200,14 @@ GetRemoteProcessId()
 
 	appendStringInfo(queryStringInfo, GET_PROCESS_ID);
 
-	ExecuteOptionalRemoteCommand(singleConnection, queryStringInfo->data, &result);
+	int queryResult = ExecuteOptionalRemoteCommand(singleConnection,
+												   queryStringInfo->data, &result);
+	if (queryResult != RESPONSE_OKAY)
+	{
+		PG_RETURN_VOID();
+	}
 
 	int64 rowCount = PQntuples(result);
-
 	if (rowCount != 1)
 	{
 		PG_RETURN_VOID();

src/backend/distributed/utils/multi_partitioning_utils.c

@@ -87,8 +87,13 @@ fix_pre_citus10_partitioned_table_constraint_names(PG_FUNCTION_ARGS)
 	}
 
 	List *taskList = CreateFixPartitionConstraintsTaskList(relationId);
+
+	/* do not do anything if there are no constraints that should be fixed */
+	if (taskList != NIL)
+	{
 		bool localExecutionSupported = true;
 		ExecuteUtilityTaskList(taskList, localExecutionSupported);
+	}
 
 	PG_RETURN_VOID();
 }