MDEV-12709 : mariabackup - during backup phase read some innodb parameter

using "show variables", rather than take the value from my.cnf. "show variables" is more accurate than my.cnf,it also works for parameters set on the mysqld command line, which is especially important for MTR.

Author: vaintroub

extra/mariabackup/backup_mysql.cc

@@ -344,7 +344,8 @@ get_mysql_vars(MYSQL *connection)
 char *innodb_data_home_dir_var = NULL;
 char *innodb_undo_directory_var = NULL;
 char *innodb_page_size_var = NULL;
-
+char *innodb_undo_tablespaces_var = NULL;
+char *endptr;
 unsigned long server_version = mysql_get_server_version(connection);
 
 bool ret = true;
@@ -372,6 +373,7 @@ get_mysql_vars(MYSQL *connection)
 {"innodb_data_home_dir", &innodb_data_home_dir_var},
 {"innodb_undo_directory", &innodb_undo_directory_var},
 {"innodb_page_size", &innodb_page_size_var},
+{"innodb_undo_tablespaces", &innodb_undo_tablespaces_var},
 {NULL, NULL}
 };
 
@@ -460,62 +462,55 @@ get_mysql_vars(MYSQL *connection)
 }
 
 /* get some default values is they are missing from my.cnf */
-if (!check_if_param_set("datadir") && datadir_var && *datadir_var) {
+if (datadir_var && *datadir_var) {
 strmake(mysql_real_data_home, datadir_var, FN_REFLEN - 1);
 mysql_data_home= mysql_real_data_home;
 }
 
-if (!check_if_param_set("innodb_data_file_path")
- && innodb_data_file_path_var && *innodb_data_file_path_var) {
+if (innodb_data_file_path_var && *innodb_data_file_path_var) {
 innobase_data_file_path = my_strdup(
 innodb_data_file_path_var, MYF(MY_FAE));
 }
 
-if (!check_if_param_set("innodb_data_home_dir")
- && innodb_data_home_dir_var && *innodb_data_home_dir_var) {
+if (innodb_data_home_dir_var && *innodb_data_home_dir_var) {
 innobase_data_home_dir = my_strdup(
 innodb_data_home_dir_var, MYF(MY_FAE));
 }
 
-if (!check_if_param_set("innodb_log_group_home_dir")
- && innodb_log_group_home_dir_var
+if (innodb_log_group_home_dir_var
  && *innodb_log_group_home_dir_var) {
 srv_log_group_home_dir = my_strdup(
 innodb_log_group_home_dir_var, MYF(MY_FAE));
 }
 
-if (!check_if_param_set("innodb_undo_directory")
- && innodb_undo_directory_var && *innodb_undo_directory_var) {
+if (innodb_undo_directory_var && *innodb_undo_directory_var) {
 srv_undo_dir = my_strdup(
 innodb_undo_directory_var, MYF(MY_FAE));
 }
 
-if (!check_if_param_set("innodb_log_files_in_group")
- && innodb_log_files_in_group_var) {
-char *endptr;
-
+if (innodb_log_files_in_group_var) {
 innobase_log_files_in_group = strtol(
 innodb_log_files_in_group_var, &endptr, 10);
 ut_ad(*endptr == 0);
 }
 
-if (!check_if_param_set("innodb_log_file_size")
- && innodb_log_file_size_var) {
-char *endptr;
-
+if (innodb_log_file_size_var) {
 innobase_log_file_size = strtoll(
 innodb_log_file_size_var, &endptr, 10);
 ut_ad(*endptr == 0);
 }
 
-if (!check_if_param_set("innodb_page_size") && innodb_page_size_var) {
-char *endptr;
-
+if (innodb_page_size_var) {
 innobase_page_size = strtoll(
 innodb_page_size_var, &endptr, 10);
 ut_ad(*endptr == 0);
 }
 
+if (innodb_undo_tablespaces_var) {
+srv_undo_tablespaces = strtoul(innodb_undo_tablespaces_var, &endptr, 10);
+ut_ad(*endptr == 0);
+}
+
 out:
 free_mysql_variables(mysql_vars);