MDEV-19264 Better support MariaDB GTID for Mariabackup's --slave-info option

Parse SHOW SLAVE STATUS output for the "Using_Gtid" column. If the value
is "No", then old log file and position is backed up, otherwise gtid_slave_pos
is backed up.

extra/mariabackup/backup_mysql.cc

@@ -1199,6 +1199,7 @@ write_slave_info(MYSQL *connection)
 	char *master = NULL;
 	char *filename = NULL;
 	char *gtid_executed = NULL;
+	char *using_gtid = NULL;
 	char *position = NULL;
 	char *gtid_slave_pos = NULL;
 	char *ptr;
@@ -1209,6 +1210,7 @@ write_slave_info(MYSQL *connection)
 		{"Relay_Master_Log_File", &filename},
 		{"Exec_Master_Log_Pos", &position},
 		{"Executed_Gtid_Set", &gtid_executed},
+		{"Using_Gtid", &using_gtid},
 		{NULL, NULL}
 	};
 
@@ -1249,7 +1251,8 @@ write_slave_info(MYSQL *connection)
 		ut_a(asprintf(&mysql_slave_position,
 			"master host '%s', purge list '%s'",
 			master, gtid_executed) != -1);
-	} else if (gtid_slave_pos && *gtid_slave_pos) {
+	} else if (gtid_slave_pos && *gtid_slave_pos &&
+			!(using_gtid && !strncmp(using_gtid, "No", 2))) {
 		/* MariaDB >= 10.0 with GTID enabled */
 		result = backup_file_printf(XTRABACKUP_SLAVE_INFO,
 			"SET GLOBAL gtid_slave_pos = '%s';\n"

mysql-test/suite/mariabackup/rpl_slave_info.result

+include/master-slave.inc
+[connection master]
+connection slave;
+###############
+# If Using_Gtid != 'No', backup gtid_slave_pos
+########################
+include/stop_slave.inc
+change master to master_use_gtid=slave_pos;
+include/start_slave.inc
+connection master;
+CREATE TABLE t(i INT);
+connection slave;
+"using_gtid: Slave_Pos"
+FOUND 1 /gtid_slave_pos/ in xtrabackup_slave_info
+NOT FOUND /MASTER_LOG_FILE/ in xtrabackup_slave_info
+###############
+# If Using_Gtid != 'No' and !gtid_slave_pos, backup master position
+########################
+include/stop_slave.inc
+SET GLOBAL gtid_slave_pos="";
+NOT FOUND /gtid_slave_pos/ in xtrabackup_slave_info
+FOUND 1 /MASTER_LOG_FILE/ in xtrabackup_slave_info
+###############
+# If Using_Gtid == 'No', backup Exec_Master_Log_Pos
+########################
+change master to master_use_gtid=no;
+include/start_slave.inc
+connection master;
+INSERT INTO t VALUES(1);
+connection slave;
+"using_gtid: No"
+NOT FOUND /gtid_slave_pos/ in xtrabackup_slave_info
+FOUND 1 /MASTER_LOG_FILE/ in xtrabackup_slave_info
+connection master;
+DROP TABLE t;
+connection slave;
+include/rpl_end.inc

mysql-test/suite/mariabackup/rpl_slave_info.test

+--source include/master-slave.inc
+
+--connection slave
+
+--echo ###############
+--echo # If Using_Gtid != 'No', backup gtid_slave_pos
+--echo ########################
+
+--source include/stop_slave.inc
+change master to master_use_gtid=slave_pos;
+--source include/start_slave.inc
+
+--connection master
+CREATE TABLE t(i INT);
+--sync_slave_with_master
+
+--let $using_gtid=query_get_value(SHOW SLAVE STATUS,Using_Gtid,1)
+--echo "using_gtid: $using_gtid"
+
+--let $targetdir=$MYSQLTEST_VARDIR/tmp/backup
+--disable_result_log
+exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf --defaults-group-suffix=.2 --slave-info --backup --target-dir=$targetdir;
+--enable_result_log
+
+--let SEARCH_FILE=$targetdir/xtrabackup_slave_info
+--let SEARCH_PATTERN=gtid_slave_pos
+--source include/search_pattern_in_file.inc
+--let SEARCH_PATTERN=MASTER_LOG_FILE
+--source include/search_pattern_in_file.inc
+
+rmdir $targetdir;
+
+--echo ###############
+--echo # If Using_Gtid != 'No' and !gtid_slave_pos, backup master position
+--echo ########################
+
+--source include/stop_slave.inc
+SET GLOBAL gtid_slave_pos="";
+
+--let $targetdir=$MYSQLTEST_VARDIR/tmp/backup
+--disable_result_log
+exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf --defaults-group-suffix=.2 --slave-info --backup --target-dir=$targetdir;
+--enable_result_log
+
+--let SEARCH_FILE=$targetdir/xtrabackup_slave_info
+--let SEARCH_PATTERN=gtid_slave_pos
+--source include/search_pattern_in_file.inc
+--let SEARCH_PATTERN=MASTER_LOG_FILE
+--source include/search_pattern_in_file.inc
+
+rmdir $targetdir;
+
+--echo ###############
+--echo # If Using_Gtid == 'No', backup Exec_Master_Log_Pos
+--echo ########################
+
+change master to master_use_gtid=no;
+--source include/start_slave.inc
+
+--connection master
+INSERT INTO t VALUES(1);
+--sync_slave_with_master
+
+--let $using_gtid=query_get_value(SHOW SLAVE STATUS,Using_Gtid,1)
+--echo "using_gtid: $using_gtid"
+
+--let $targetdir=$MYSQLTEST_VARDIR/tmp/backup
+--disable_result_log
+exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf --defaults-group-suffix=.2 --slave-info --backup --target-dir=$targetdir;
+--enable_result_log
+
+--let SEARCH_FILE=$targetdir/xtrabackup_slave_info
+--let SEARCH_PATTERN=gtid_slave_pos
+--source include/search_pattern_in_file.inc
+--let SEARCH_PATTERN=MASTER_LOG_FILE
+--source include/search_pattern_in_file.inc
+
+rmdir $targetdir;
+
+# Cleanup
+--connection master
+DROP TABLE t;
+--sync_slave_with_master
+--source include/rpl_end.inc