Refactor show matrix to handle node IDs correctly.

Previously the code assumed repmgr node IDs to be sequential,
which is not guaranteed to be the case. With a non-sequential
list of node IDs, an incorrect node id would be displayed,
and memory accessed beyond the bounds of the matrix array.

The refactored code is considerably less elegant than the original
but will correctly handle a non-sequential sequence of node IDs.

repmgr.c

@@ -113,7 +113,7 @@ static void get_barman_property(char *dst, char *name, char *local_repmgr_direct
 
 static char *string_skip_prefix(const char *prefix, char *string);
 static char *string_remove_trailing_newlines(char *string);
-static int  build_cluster_matrix(int **matrix, char **node_names, int *name_length);
+static int build_cluster_matrix(t_node_status_matrix *matrix, int *name_length);
 static int  build_cluster_diagnose(int **cube, char **node_names, int *name_length);
 
 static char *make_pg_path(char *file);
@@ -163,6 +163,8 @@ static void parse_pg_basebackup_options(const char *pg_basebackup_options, t_bas
 static void config_file_list_init(t_configfile_list *list, int max_size);
 static void config_file_list_add(t_configfile_list *list, const char *file, const char *filename, bool in_data_dir);
 
+static void matrix_set_node_status(t_node_status_matrix *matrix, int node_id, int connection_node_id, int connection_status);
+
 /* Global variables */
 static PQconninfoOption *opts = NULL;
 
@@ -1109,17 +1111,42 @@ do_cluster_show(void)
 	PQclear(res);
 }
 
+
+static void
+matrix_set_node_status(t_node_status_matrix *matrix, int node_id, int connection_node_id, int connection_status)
+{
+	int i, j;
+//	printf("matrix_set_node_status() %i %i %i\n", node_id, connection_node_id, connection_status);
+
+	for (i = 0; i < matrix->length; i++)
+	{
+//		printf("xx %i\n", i);
+
+		if (matrix->matrix_list[i]->node_id == node_id)
+		{
+			for (j = 0; j < matrix->length; j++)
+			{
+//XS				printf(" xx %i\n", j);
+
+				if (matrix->matrix_list[i]->node_status_list[j]->node_id == connection_node_id)
+				{
+					matrix->matrix_list[i]->node_status_list[j]->node_status = connection_status;
+					break;
+				}
+			}
+			break;
+		}
+	}
+}
+
 static int
-build_cluster_matrix(int **matrix, char **node_names, int *name_length)
+build_cluster_matrix(t_node_status_matrix *matrix, int *name_length)
 {
 	PGconn	   *conn;
 	PGresult   *res;
 	char		sqlquery[QUERY_STR_LEN];
-	int			i, j;
 	int			n;
-
+	int			i, j;
-	int			x, y;
-
 	int			local_node_id;
 
 	PQExpBufferData command;
@@ -1164,49 +1191,53 @@ build_cluster_matrix(int **matrix, char **node_names, int *name_length)
 	/*
 	 * Allocate an empty matrix
 	 *
-	 * -2 == NULL
+	 * -2 == NULL  ?
-	 * -1 == Error
+	 * -1 == Error x
-	 *  0 == OK
+	 *  0 == OK    *
 	 */
 	n = PQntuples(res);
-	*matrix = (int *) pg_malloc(sizeof(int) * n * n);
-	for (i = 0; i < n * n; i++)
-		(*matrix)[i] = -2;
 
-	/*
+	matrix->length = n;
-	 * Find the maximum length of a node name
+
-	 */
+	matrix->matrix_list = (t_node_status_matrix_rec **) pg_malloc0(sizeof(t_node_status_matrix_rec) * n);
+
+
+	/* Initialise matrix structure for each node */
 	for (i = 0; i < n; i++)
 	{
 		int name_length_cur;
 
-		name_length_cur	= strlen(PQgetvalue(res, i, 2));
+		matrix->matrix_list[i] = (t_node_status_matrix_rec *) pg_malloc0(sizeof(t_node_status_matrix_rec));
+
+		matrix->matrix_list[i]->node_id = atoi(PQgetvalue(res, i, 4));
+		strncpy(matrix->matrix_list[i]->node_name, PQgetvalue(res, i, 2), MAXLEN);
+
+		/*
+		 * Find the maximum length of a node name
+		 */
+		name_length_cur	= strlen(matrix->matrix_list[i]->node_name);
 		if (name_length_cur > *name_length)
 			*name_length = name_length_cur;
-	}
 
-	/*
+		matrix->matrix_list[i]->node_status_list = (t_node_status_rec **) pg_malloc0(sizeof(t_node_status_rec) * n);
-	 * Save node names into an array
-	 */
 
-	*node_names = (char *) pg_malloc((*name_length + 1) * n);
+		for (j = 0; j < n; j++)
-
-	for (i = 0; i < n; i++)
 		{
-		strncpy(*node_names + i * (*name_length + 1),
+			matrix->matrix_list[i]->node_status_list[j] = (t_node_status_rec *) pg_malloc0(sizeof(t_node_status_rec));
-				PQgetvalue(res, i, 2),
+			matrix->matrix_list[i]->node_status_list[j]->node_id = atoi(PQgetvalue(res, j, 4));
-				strlen(PQgetvalue(res, i, 2)) + 1);
+			matrix->matrix_list[i]->node_status_list[j]->node_status = -2;  /* default unknown */
+		}
 	}
 
-	/*
+	/* Fetch `repmgr cluster show --csv` output for each node */
-	 * Build the connection matrix
-	 */
 
 	for (i = 0; i < n; i++)
 	{
 		int connection_status;
 		t_conninfo_param_list remote_conninfo;
 		char *host, *p;
+		int connection_node_id = atoi(PQgetvalue(res, i, 4));
+		int			x, y;
 
 		initialize_conninfo_params(&remote_conninfo, false);
 		parse_conninfo_string(PQgetvalue(res, i, 0),
@@ -1221,16 +1252,27 @@ build_cluster_matrix(int **matrix, char **node_names, int *name_length)
 		connection_status =
 			(PQstatus(conn) == CONNECTION_OK) ? 0 : -1;
 
-		(*matrix)[(local_node_id - 1) * n + i] =
+
-			connection_status;
+		matrix_set_node_status(matrix,
+							   local_node_id,
+							   connection_node_id,
+							   connection_status);
+
 
 		if (connection_status)
 			continue;
 
-		if (i + 1 == local_node_id)
+		/* We don't need to issue `cluster show --csv` for the local node */
+		if (connection_node_id == local_node_id)
 			continue;
 
 		initPQExpBuffer(&command);
+
+		/*
+		 * We'll pass cluster name and database connection string to the remote
+		 * repmgr - those are the only values it needs to work, and saves us
+		 * making assumptions about the location of repmgr.conf
+		 */
 		appendPQExpBuffer(&command,
 						  "\"%s -d '%s' --cluster '%s' ",
 						  make_pg_path("repmgr"),
@@ -1269,8 +1311,12 @@ build_cluster_matrix(int **matrix, char **node_names, int *name_length)
 				PQfinish(conn);
 				exit(ERR_INTERNAL);
 			}
-			(*matrix)[i * n + (x - 1)] =
+
-				(y == -1) ? -1 : 0;
+			matrix_set_node_status(matrix,
+								   connection_node_id,
+								   x,
+								   (y == -1) ? -1 : 0 );
+
 			while (*p && (*p != '\n'))
 				p++;
 			if (*p == '\n')
@@ -1285,25 +1331,30 @@ build_cluster_matrix(int **matrix, char **node_names, int *name_length)
 	return n;
 }
 
+
+
 static void
 do_cluster_matrix()
 {
 	int			i, j;
 	int			n;
-	char	   *node_names;
-	int		   *matrix;
 	const char *node_header = "Name";
 	int			name_length = strlen(node_header);
 
-	n = build_cluster_matrix(&matrix, &node_names, &name_length);
+	t_node_status_matrix *matrix_new = (t_node_status_matrix *) pg_malloc(sizeof(t_node_status_matrix));
+
+	n = build_cluster_matrix(matrix_new, &name_length);
 
 	if (runtime_options.csv_mode)
 	{
+
 		for (i = 0; i < n; i++)
 			for (j = 0; j < n; j++)
 				printf("%d,%d,%d\n",
-					   i + 1, j + 1,
+					   matrix_new->matrix_list[i]->node_id,
-					   matrix[i * n + j]);
+					   matrix_new->matrix_list[i]->node_status_list[j]->node_id,
+					   matrix_new->matrix_list[i]->node_status_list[j]->node_status);
+
 	}
 	else
 	{
@@ -1311,7 +1362,7 @@ do_cluster_matrix()
 
 		printf("%*s | Id ", name_length, node_header);
 		for (i = 0; i < n; i++)
-			printf("| %2d ", i+1);
+			printf("| %2d ", matrix_new->matrix_list[i]->node_id);
 		printf("\n");
 
 		for (i = 0; i < name_length; i++)
@@ -1324,10 +1375,12 @@ do_cluster_matrix()
 		for (i = 0; i < n; i++)
 		{
 			printf("%*s | %2d ", name_length,
-				   node_names + (name_length + 1) * i, i + 1);
+				   matrix_new->matrix_list[i]->node_name,
+				   matrix_new->matrix_list[i]->node_id);
 			for (j = 0; j < n; j++)
 			{
-				switch (matrix[i * n + j])
+				//switch (matrix[i * n + j])
+				switch (matrix_new->matrix_list[i]->node_status_list[j]->node_status)
 				{
 				case -2:
 					c = '?';

repmgr.h

@@ -165,5 +165,32 @@ typedef struct
 	t_configfile_info **files;
 } t_configfile_list;
 
+
+typedef struct
+{
+	int node_id;
+	int node_status;
+} t_node_status_rec;
+
+typedef struct
+{
+	int node_id;
+	char node_name[MAXLEN];
+	t_node_status_rec **node_status_list;
+} t_node_status_matrix_rec;
+
+typedef struct
+{
+	int length;
+	t_node_status_matrix_rec **matrix_list;
+} t_node_status_matrix;
+
+typedef struct
+{
+	int node_id;
+	t_node_status_matrix **node_matrix;
+} t_node_status_cube;
+
+
 #define T_CONFIGFILE_LIST_INITIALIZER { 0, 0, NULL }
 #endif