MDEV-27524: Incorrect binlogs after Galera SST using rsync and mariabackup

This commit adds correct handling of binlogs for SST using rsync
or mariabackup. Before this fix, binlogs were handled incorrectly -
- only one (last) binary log file was transferred during SST, which
then led to various failures (for example, when trying to list all
events from the binary log). These bugs were long masked by flaws
in the primitive binlogs handling code in the SST scripts, which
causing binary logs files to be erased after transfer or not added
to the binlog index on the joiner node. Now the correct transfer
of all binary logs (not just the last of the binary log files) has
been implemented both for the rsync (at the script level) and for
the mariabackup (at the level of the main utility code).

This commit also adds a new sst_max_binlogs=<n> parameter, which
can be located in the [sst] section or in the [xtrabackup] section
(historically, supported for mariabackup only, not for rsync), or
in one of the server sections. This parameter specifies the number
of binary log files to be sent to the joiner node during SST. This
option is added for compatibility with old SST scripting behavior,
which can be emulated by setting the sst_max_binlogs=1 (although
in general this can cause problems for the reasons described above).
In addition, setting the sst_max_binlogs=0 can be used to suppress
the transmission of binary logs to the joiner nodes during SST
(although sometimes a single file with the current binary log can
still be transmitted to the joiner, even with sst_max_binlogs=0,
because this sometimes necessary in modes that involve the use of
GTIDs with Galera).

Also, this commit ensures correct handling of paths to various
innodb files and directories in the SST scripts, and fixes some
problems with this that existed in mariabackup utility (which
were associated with incorrect handling of the innodb_data_dir
parameter in some scenarios).

In addition, this commit contains the following enhancements:

 1) Added tests for mtr, which check the correct work with binlogs
    after SST (using rsync and mariabackup);
 2) Added correct handling of slashes at the end of all paths that
    the SST script receives as parameters;
 3) Improved parsing code for --mysqld-args parameters. Now it
    correctly processes the sequence "--" after the name of the
    one-letter option;
 4) Checking the secret signature during joiner authentication
    is made independent of presence of bash (as a unix shell)
    in the system and diff utility no longer needed to check
    certificates compliance;
 5) All directories that are necessary for the correct placement
    of various logs are automatically created by SST scripts in
    advance (before running mariabackup on the joiner node);
 6) Removal of old binary logs on joiner is done using the binlog
    index (if it exists) (not only by fixed pattern that based
    on the current binlog name, as before);
 7) Paths for placing binary logs are correctly processed if they
    are set as relative paths (to the datadir);
 8) SST scripts are made even more resistant to spaces in filenames
    (now for binlogs);
 9) In case of failure, SST scripts now always end with an exit
    code other than zero;
10) SST script for rsync now correctly create a tar file with
    the binlogs, even if the paths to them (in the binlog index
    file) are specified as a mix of absolute and relative paths,
    and even if they do not match with the datadir path specified
    in the current configuration settings.

7 files changed, 330 insertions, 89 deletions

diff --git a/extra/mariabackup/backup_copy.cc b/extra/mariabackup/backup_copy.cc
index c46c32213d6..9c6f3665a6a 100644
--- a/extra/mariabackup/backup_copy.cc
+++ b/extra/mariabackup/backup_copy.cc
@@ -582,7 +582,6 @@ datafile_read(datafile_cur_t *cursor)
 Check to see if a file exists.
 Takes name of the file to check.
 @return true if file exists. */
-static
 bool
 file_exists(const char *filename)
 {
@@ -1547,13 +1546,14 @@ bool backup_start(CorruptedPages &corrupted_pages)
 		if (!write_galera_info(mysql_connection)) {
 			return(false);
 		}
-		write_current_binlog_file(mysql_connection);
 	}
 
-	if (opt_binlog_info == BINLOG_INFO_ON) {
+	bool with_binlogs = opt_binlog_info == BINLOG_INFO_ON;
 
-		lock_binlog_maybe(mysql_connection);
-		write_binlog_info(mysql_connection);
+	if (with_binlogs || opt_galera_info) {
+		if (!write_current_binlog_file(mysql_connection, with_binlogs)) {
+			return(false);
+		}
 	}
 
 	if (have_flush_engine_logs && !opt_no_lock) {
@@ -1587,15 +1587,34 @@ void backup_release()
 	}
 }
 
+static const char *default_buffer_pool_file = "ib_buffer_pool";
+
+static
+const char * get_buffer_pool_filename(size_t *length)
+{
+	/* If mariabackup is run for Galera, then the file
+	name is changed to the default so that the receiving
+	node can find this file and rename it according to its
+	settings, otherwise we keep the original file name: */
+	size_t dir_length = 0;
+	const char *dst_name = default_buffer_pool_file;
+	if (!opt_galera_info) {
+		dir_length = dirname_length(buffer_pool_filename);
+		dst_name = buffer_pool_filename + dir_length;
+	}
+	if (length) {
+		*length=dir_length;
+	}
+	return dst_name;
+}
+
 /** Finish after backup_start() and backup_release() */
 bool backup_finish()
 {
 	/* Copy buffer pool dump or LRU dump */
 	if (!opt_rsync) {
 		if (buffer_pool_filename && file_exists(buffer_pool_filename)) {
-			const char *dst_name;
-
-			dst_name = trim_dotslash(buffer_pool_filename);
+			const char *dst_name = get_buffer_pool_filename(NULL);
 			copy_file(ds_data, buffer_pool_filename, dst_name, 0);
 		}
 		if (file_exists("ib_lru_dump")) {
@@ -1684,17 +1703,14 @@ ibx_copy_incremental_over_full()
 
 		/* copy buffer pool dump */
 		if (innobase_buffer_pool_filename) {
-			const char *src_name;
-
-			src_name = trim_dotslash(innobase_buffer_pool_filename);
+			const char *src_name = get_buffer_pool_filename(NULL);
 
 			snprintf(path, sizeof(path), "%s/%s",
 				xtrabackup_incremental_dir,
 				src_name);
 
 			if (file_exists(path)) {
-				copy_file(ds_data, path,
-					  innobase_buffer_pool_filename, 0);
+				copy_file(ds_data, path, src_name, 0);
 			}
 		}
 
@@ -1929,6 +1945,14 @@ copy_back()
 
 	datadir_node_init(&node);
 
+	/* If mariabackup is run for Galera, then the file
+	name is changed to the default so that the receiving
+	node can find this file and rename it according to its
+	settings, otherwise we keep the original file name: */
+	size_t dir_length;
+	const char *src_buffer_pool;
+	src_buffer_pool = get_buffer_pool_filename(&dir_length);
+
 	while (datadir_iter_next(it, &node)) {
 		const char *ext_list[] = {"backup-my.cnf",
 			"xtrabackup_binary", "xtrabackup_binlog_info",
@@ -1991,6 +2015,11 @@ copy_back()
 			continue;
 		}
 
+		/* skip buffer pool dump */
+		if (!strcmp(filename, src_buffer_pool)) {
+			continue;
+		}
+
 		/* skip innodb data files */
 		is_ibdata_file = false;
 		for (Tablespace::const_iterator iter(srv_sys_space.begin()),
@@ -2013,23 +2042,18 @@ copy_back()
 
 	/* copy buffer pool dump */
 
-	if (innobase_buffer_pool_filename) {
-		const char *src_name;
-		char path[FN_REFLEN];
-
-		src_name = trim_dotslash(innobase_buffer_pool_filename);
-
-		snprintf(path, sizeof(path), "%s/%s",
-			mysql_data_home,
-			src_name);
-
-		/* could be already copied with other files
-		from data directory */
-		if (file_exists(src_name) &&
-			!file_exists(innobase_buffer_pool_filename)) {
-			copy_or_move_file(src_name,
-					  innobase_buffer_pool_filename,
-					  mysql_data_home, 0);
+	if (file_exists(src_buffer_pool)) {
+		char dst_dir[FN_REFLEN];
+		while (IS_TRAILING_SLASH(buffer_pool_filename, dir_length)) {
+			dir_length--;
+		}
+		memcpy(dst_dir, buffer_pool_filename, dir_length);
+		dst_dir[dir_length] = 0;
+		if (!(ret = copy_or_move_file(src_buffer_pool,
+				src_buffer_pool,
+				dst_dir, 1)))
+		{
+			goto cleanup;
 		}
 	}
 
diff --git a/extra/mariabackup/backup_copy.h b/extra/mariabackup/backup_copy.h
index 62b2b1bc232..858182001ce 100644
--- a/extra/mariabackup/backup_copy.h
+++ b/extra/mariabackup/backup_copy.h
@@ -32,6 +32,13 @@ copy_file(ds_ctxt_t *datasink,
 	  const char *dst_file_path,
 	  uint thread_n);
 
+/************************************************************************
+Check to see if a file exists.
+Takes name of the file to check.
+@return true if file exists. */
+bool
+file_exists(const char *filename);
+
 /** Start --backup */
 bool backup_start(CorruptedPages &corrupted_pages);
 /** Release resources after backup_start() */
diff --git a/extra/mariabackup/backup_mysql.cc b/extra/mariabackup/backup_mysql.cc
index 824b8b6d5f3..78af2b7f5ac 100644
--- a/extra/mariabackup/backup_mysql.cc
+++ b/extra/mariabackup/backup_mysql.cc
@@ -83,7 +83,6 @@ os_event_t	kill_query_thread_stop;
 bool sql_thread_started = false;
 char *mysql_slave_position = NULL;
 char *mysql_binlog_position = NULL;
-char *buffer_pool_filename = NULL;
 
 /* History on server */
 time_t history_start_time;
@@ -1333,27 +1332,29 @@ cleanup:
 }
 
 
+static
+bool
+write_binlog_info(MYSQL *connection, char *log_bin_dir,
+		  MYSQL_RES *mysql_result, my_ulonglong n_rows,
+		  my_ulonglong start);
+
 /*********************************************************************//**
 Flush and copy the current binary log file into the backup,
 if GTID is enabled */
 bool
-write_current_binlog_file(MYSQL *connection)
+write_current_binlog_file(MYSQL *connection, bool write_binlogs)
 {
+	char *log_bin = NULL;
+	char *filename = NULL;
+	char *position = NULL;
 	char *executed_gtid_set = NULL;
 	char *gtid_binlog_state = NULL;
-	char *log_bin_file = NULL;
 	char *log_bin_dir = NULL;
 	bool gtid_exists;
 	bool result = true;
-	char filepath[FN_REFLEN];
 
-	mysql_variable status[] = {
-		{"Executed_Gtid_Set", &executed_gtid_set},
-		{NULL, NULL}
-	};
-
-	mysql_variable status_after_flush[] = {
-		{"File", &log_bin_file},
+	mysql_variable log_bin_var[] = {
+		{"@@GLOBAL.log_bin", &log_bin},
 		{NULL, NULL}
 	};
 
@@ -1363,21 +1364,36 @@ write_current_binlog_file(MYSQL *connection)
 		{NULL, NULL}
 	};
 
+	mysql_variable status[] = {
+		{"File", &filename},
+		{"Position", &position},
+		{"Executed_Gtid_Set", &executed_gtid_set},
+		{NULL, NULL}
+	};
+
+	read_mysql_variables(connection, "SELECT @@GLOBAL.log_bin", log_bin_var, false);
+
+	/* Do not create xtrabackup_binlog_info if binary log is disabled: */
+	if (strncmp(log_bin, "1", 2) != 0) {
+		goto binlog_disabled;
+	}
+
+	lock_binlog_maybe(connection);
+
 	read_mysql_variables(connection, "SHOW MASTER STATUS", status, false);
+
+	/* Do not create xtrabackup_binlog_info if replication
+	has not started yet: */
+	if (filename == NULL || position == NULL) {
+		goto no_replication;
+	}
+
 	read_mysql_variables(connection, "SHOW VARIABLES", vars, true);
 
 	gtid_exists = (executed_gtid_set && *executed_gtid_set)
 			|| (gtid_binlog_state && *gtid_binlog_state);
 
-	if (gtid_exists) {
-		size_t log_bin_dir_length;
-
-		lock_binlog_maybe(connection);
-
-		xb_mysql_query(connection, "FLUSH BINARY LOGS", false);
-
-		read_mysql_variables(connection, "SHOW MASTER STATUS",
-			status_after_flush, false);
+	if (write_binlogs || gtid_exists) {
 
 		if (opt_log_bin != NULL && strchr(opt_log_bin, FN_LIBCHAR)) {
 			/* If log_bin is set, it has priority */
@@ -1387,34 +1403,89 @@ write_current_binlog_file(MYSQL *connection)
 			log_bin_dir = strdup(opt_log_bin);
 		} else if (log_bin_dir == NULL) {
 			/* Default location is MySQL datadir */
-			log_bin_dir = strdup("./");
+			log_bin_dir = static_cast<char*>(malloc(3));
+			ut_a(log_bin_dir);
+			log_bin_dir[0] = '.';
+			log_bin_dir[1] = FN_LIBCHAR;
+			log_bin_dir[2] = 0;
 		}
 
+		size_t log_bin_dir_length;
+
 		dirname_part(log_bin_dir, log_bin_dir, &log_bin_dir_length);
 
 		/* strip final slash if it is not the only path component */
-		if (log_bin_dir_length > 1 &&
-		    log_bin_dir[log_bin_dir_length - 1] == FN_LIBCHAR) {
-			log_bin_dir[log_bin_dir_length - 1] = 0;
+		while (IS_TRAILING_SLASH(log_bin_dir, log_bin_dir_length)) {
+			log_bin_dir_length--;
 		}
+		log_bin_dir[log_bin_dir_length] = 0;
 
-		if (log_bin_dir == NULL || log_bin_file == NULL) {
-			msg("Failed to get master binlog coordinates from "
-				"SHOW MASTER STATUS");
+		if (log_bin_dir == NULL) {
+			msg("Failed to locate binary log files");
 			result = false;
 			goto cleanup;
 		}
 
-		snprintf(filepath, sizeof(filepath), "%s%c%s",
-			 log_bin_dir, FN_LIBCHAR, log_bin_file);
-		result = copy_file(ds_data, filepath, log_bin_file, 0);
+		uint max_binlogs;
+		max_binlogs = opt_max_binlogs;
+		if (max_binlogs == 0) {
+			if (gtid_exists) {
+				max_binlogs = 1;
+			} else {
+				goto cleanup;
+			}
+		}
+
+		xb_mysql_query(connection, "FLUSH BINARY LOGS", false);
+
+		MYSQL_RES *mysql_result;
+
+		mysql_result = xb_mysql_query(connection, "SHOW BINARY LOGS", true);
+
+		ut_ad(mysql_num_fields(mysql_result) >= 2);
+
+		my_ulonglong n_rows;
+		my_ulonglong start;
+
+		n_rows = mysql_num_rows(mysql_result);
+
+		start = 0;
+		if (max_binlogs < n_rows) {
+			start = n_rows - max_binlogs;
+		}
+		if (start) {
+			mysql_data_seek(mysql_result, start);
+		}
+
+		MYSQL_ROW row;
+		while ((row = mysql_fetch_row(mysql_result))) {
+			const char *binlog_name = row[0];
+			char filepath[FN_REFLEN];
+			snprintf(filepath, sizeof(filepath), "%s%c%s",
+				 log_bin_dir, FN_LIBCHAR, binlog_name);
+			if (file_exists(filepath)) {
+				result = copy_file(ds_data, filepath, binlog_name, 0);
+				if (!result) break;
+			}
+		}
+
+		if (result) {
+			write_binlog_info(connection, log_bin_dir,
+					  mysql_result, n_rows, start);
+		}
+
+		mysql_free_result(mysql_result);
 	}
 
 cleanup:
-	free_mysql_variables(status_after_flush);
-	free_mysql_variables(status);
 	free_mysql_variables(vars);
 
+no_replication:
+	free_mysql_variables(status);
+
+binlog_disabled:
+	free_mysql_variables(log_bin_var);
+
 	return(result);
 }
 
@@ -1422,8 +1493,11 @@ cleanup:
 /*********************************************************************//**
 Retrieves MySQL binlog position and
 saves it in a file. It also prints it to stdout. */
+static
 bool
-write_binlog_info(MYSQL *connection)
+write_binlog_info(MYSQL *connection, char *log_bin_dir,
+		  MYSQL_RES *mysql_result, my_ulonglong n_rows,
+		  my_ulonglong start)
 {
 	char *filename = NULL;
 	char *position = NULL;
@@ -1431,9 +1505,13 @@ write_binlog_info(MYSQL *connection)
 	char *gtid_current_pos = NULL;
 	char *gtid_executed = NULL;
 	char *gtid = NULL;
-	bool result;
+	char *buffer;
+	char *buf;
+	size_t total;
+	bool result = true;
 	bool mysql_gtid;
 	bool mariadb_gtid;
+	bool with_gtid;
 
 	mysql_variable status[] = {
 		{"File", &filename},
@@ -1451,39 +1529,106 @@ write_binlog_info(MYSQL *connection)
 	read_mysql_variables(connection, "SHOW MASTER STATUS", status, false);
 	read_mysql_variables(connection, "SHOW VARIABLES", vars, true);
 
-	if (filename == NULL || position == NULL) {
-		/* Do not create xtrabackup_binlog_info if binary
-		log is disabled */
-		result = true;
-		goto cleanup;
-	}
-
-	mysql_gtid = ((gtid_mode != NULL) && (strcmp(gtid_mode, "ON") == 0));
-	mariadb_gtid = (gtid_current_pos != NULL);
+	mysql_gtid = gtid_mode && (strcmp(gtid_mode, "ON") == 0);
+	mariadb_gtid = gtid_current_pos && *gtid_current_pos;
 
-	gtid = (gtid_executed != NULL ? gtid_executed : gtid_current_pos);
+	gtid = (gtid_executed && *gtid_executed) ? gtid_executed : gtid_current_pos;
 
-	if (mariadb_gtid || mysql_gtid) {
+	with_gtid = mariadb_gtid || mysql_gtid;
+	if (with_gtid) {
 		ut_a(asprintf(&mysql_binlog_position,
 			"filename '%s', position '%s', "
 			"GTID of the last change '%s'",
 			filename, position, gtid) != -1);
-		result = backup_file_printf(XTRABACKUP_BINLOG_INFO,
-					    "%s\t%s\t%s\n", filename, position,
-					    gtid);
 	} else {
 		ut_a(asprintf(&mysql_binlog_position,
 			"filename '%s', position '%s'",
 			filename, position) != -1);
-		result = backup_file_printf(XTRABACKUP_BINLOG_INFO,
-					    "%s\t%s\n", filename, position);
 	}
 
+	mysql_data_seek(mysql_result, start);
+
+	MYSQL_ROW row;
+	my_ulonglong current;
+
+	total = 1;
+	current = start;
+	while ((row = mysql_fetch_row(mysql_result))) {
+		const char *binlog_name = row[0];
+		/* The position in the current binlog is taken from
+		the global variable, but for the previous ones it is
+		determined by their length: */
+		const char *binlog_pos =
+			++current == n_rows ? position : row[1];
+		total += strlen(binlog_name) + strlen(binlog_pos) + 2;
+		if (with_gtid && current != n_rows) {
+			/* Add the "\t[]" length to the buffer size: */
+			total += 3;
+		}
+	}
+	/* For the last of the binray log files, also add
+	the length of the GTID (+ one character for '\t'): */
+	if (with_gtid) {
+		total += strlen(gtid) + 1;
+	}
+
+	buffer = static_cast<char*>(malloc(total));
+	if (!buffer) {
+		msg("Failed to allocate memory for temporary buffer");
+		result = false;
+		goto cleanup;
+	}
+
+	mysql_data_seek(mysql_result, start);
+
+	buf = buffer;
+	current = start;
+	while ((row = mysql_fetch_row(mysql_result))) {
+		const char *binlog_name = row[0];
+		char filepath[FN_REFLEN];
+		snprintf(filepath, sizeof(filepath), "%s%c%s",
+			 log_bin_dir, FN_LIBCHAR, binlog_name);
+		current++;
+		if (file_exists(filepath)) {
+			/* The position in the current binlog is taken from
+			the global variable, but for the previous ones it is
+			determined by their length: */
+			char *binlog_pos =
+				current == n_rows ? position : row[1];
+			int bytes;
+			if (with_gtid) {
+				bytes = snprintf(buf, total, "%s\t%s\t%s\n",
+						 binlog_name, binlog_pos,
+						 current == n_rows ? gtid : "[]");
+			} else {
+				bytes = snprintf(buf, total, "%s\t%s\n",
+						 binlog_name, binlog_pos);
+			}
+			if (bytes <= 0) {
+				goto buffer_overflow;
+			}
+			buf += bytes;
+			total -= bytes;
+		}
+	}
+
+	if (buf != buffer) {
+		result = backup_file_printf(XTRABACKUP_BINLOG_INFO, "%s", buffer);
+	}
+
+cleanup2:
+	free(buffer);
+
 cleanup:
-	free_mysql_variables(status);
 	free_mysql_variables(vars);
+	free_mysql_variables(status);
 
 	return(result);
+
+buffer_overflow:
+	msg("Internal error: buffer overflow in the write_binlog_info()");
+	result = false;
+	goto cleanup2;
 }
 
 struct escape_and_quote
@@ -1811,7 +1956,6 @@ backup_cleanup()
 {
 	free(mysql_slave_position);
 	free(mysql_binlog_position);
-	free(buffer_pool_filename);
 
 	if (mysql_connection) {
 		mysql_close(mysql_connection);
diff --git a/extra/mariabackup/backup_mysql.h b/extra/mariabackup/backup_mysql.h
index b61fa2362c6..5e78281e1cb 100644
--- a/extra/mariabackup/backup_mysql.h
+++ b/extra/mariabackup/backup_mysql.h
@@ -28,7 +28,6 @@ extern time_t history_lock_time;
 extern bool sql_thread_started;
 extern char *mysql_slave_position;
 extern char *mysql_binlog_position;
-extern char *buffer_pool_filename;
 
 /** connection to mysql server */
 extern MYSQL *mysql_connection;
@@ -62,10 +61,7 @@ void
 unlock_all(MYSQL *connection);
 
 bool
-write_current_binlog_file(MYSQL *connection);
-
-bool
-write_binlog_info(MYSQL *connection);
+write_current_binlog_file(MYSQL *connection, bool write_binlogs);
 
 bool
 write_xtrabackup_info(MYSQL *connection, const char * filename, bool history,
diff --git a/extra/mariabackup/common.h b/extra/mariabackup/common.h
index 1973512ad82..beb49524608 100644
--- a/extra/mariabackup/common.h
+++ b/extra/mariabackup/common.h
@@ -187,4 +187,14 @@ xb_read_full(File fd, uchar *buf, size_t len)
 	return tlen;
 }
 
+#ifdef _WIN32
+#define IS_TRAILING_SLASH(name, length) \
+	((length) > 1 && \
+		(name[(length) - 1] == '/' || \
+		 name[(length) - 1] == '\\'))
+#else
+#define IS_TRAILING_SLASH(name, length) \
+	((length) > 1 && name[(length) - 1] == FN_LIBCHAR)
+#endif
+
 #endif
diff --git a/extra/mariabackup/xtrabackup.cc b/extra/mariabackup/xtrabackup.cc
index bb1e2eaf42d..c1b2a1a9c85 100644
--- a/extra/mariabackup/xtrabackup.cc
+++ b/extra/mariabackup/xtrabackup.cc
@@ -240,7 +240,8 @@ long innobase_log_buffer_size = 1024*1024L;
 long innobase_open_files = 300L;
 
 longlong innobase_page_size = (1LL << 14); /* 16KB */
-char*	innobase_buffer_pool_filename = NULL;
+char *innobase_buffer_pool_filename = NULL;
+char *buffer_pool_filename = NULL;
 
 /* The default values for the following char* start-up parameters
 are determined in innobase_init below: */
@@ -347,6 +348,7 @@ uint opt_lock_wait_timeout = 0;
 uint opt_lock_wait_threshold = 0;
 uint opt_debug_sleep_before_unlock = 0;
 uint opt_safe_slave_backup_timeout = 0;
+uint opt_max_binlogs = UINT_MAX;
 
 const char *opt_history = NULL;
 
@@ -1051,7 +1053,8 @@ enum options_xtrabackup
   OPT_BACKUP_ROCKSDB,
   OPT_XTRA_CHECK_PRIVILEGES,
   OPT_XB_IGNORE_INNODB_PAGE_CORRUPTION,
-  OPT_INNODB_FORCE_RECOVERY
+  OPT_INNODB_FORCE_RECOVERY,
+  OPT_MAX_BINLOGS
 };
 
 struct my_option xb_client_options[]= {
@@ -1454,6 +1457,17 @@ struct my_option xb_client_options[]= {
      &opt_log_innodb_page_corruption, &opt_log_innodb_page_corruption, 0,
      GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
 
+    {"sst_max_binlogs", OPT_MAX_BINLOGS,
+     "Number of recent binary logs to be included in the backup. "
+     "Setting this parameter to zero normally disables transmission "
+     "of binary logs to the joiner nodes during SST using Galera. "
+     "But sometimes a single current binlog can still be transmitted "
+     "to the joiner even with sst_max_binlogs=0, because it is "
+     "required for Galera to work properly with GTIDs support.",
+     (G_PTR *) &opt_max_binlogs,
+     (G_PTR *) &opt_max_binlogs, 0, GET_UINT, OPT_ARG,
+     UINT_MAX, 0, UINT_MAX, 0, 1, 0},
+
 #define MYSQL_CLIENT
 #include "sslopt-longopts.h"
 #undef MYSQL_CLIENT
@@ -6272,6 +6286,44 @@ check_all_privileges()
 	}
 }
 
+static
+void
+xb_init_buffer_pool(const char * filename)
+{
+	if (filename &&
+#ifdef _WIN32
+		(filename[0] == '/'  ||
+		 filename[0] == '\\' ||
+		 strchr(filename, ':')))
+#else
+		filename[0] == FN_LIBCHAR)
+#endif
+	{
+		buffer_pool_filename = strdup(filename);
+	} else {
+		char filepath[FN_REFLEN];
+		char *dst_dir =
+			(innobase_data_home_dir && *innobase_data_home_dir) ?
+			 innobase_data_home_dir : mysql_data_home;
+		size_t dir_length;
+		if (dst_dir && *dst_dir) {
+			dir_length = strlen(dst_dir);
+			while (IS_TRAILING_SLASH(dst_dir, dir_length)) {
+				dir_length--;
+			}
+			memcpy(filepath, dst_dir, dir_length);
+		}
+		else {
+			filepath[0] = '.';
+			dir_length = 1;
+		}
+		snprintf(filepath + dir_length,
+			sizeof(filepath) - dir_length, "%c%s", FN_LIBCHAR,
+			filename ? filename : "ib_buffer_pool");
+		buffer_pool_filename = strdup(filepath);
+	}
+}
+
 bool
 xb_init()
 {
@@ -6336,11 +6388,15 @@ xb_init()
 		if (!get_mysql_vars(mysql_connection)) {
 			return(false);
 		}
+		xb_init_buffer_pool(buffer_pool_filename);
+
 		if (opt_check_privileges) {
 			check_all_privileges();
 		}
 		history_start_time = time(NULL);
 
+	} else {
+		xb_init_buffer_pool(innobase_buffer_pool_filename);
 	}
 
 	return(true);
@@ -6634,6 +6690,8 @@ int main(int argc, char **argv)
 	free_error_messages();
 	mysql_mutex_destroy(&LOCK_error_log);
 
+	free(buffer_pool_filename);
+
 	if (status == EXIT_SUCCESS) {
 		msg("completed OK!");
 	}
diff --git a/extra/mariabackup/xtrabackup.h b/extra/mariabackup/xtrabackup.h
index e2955f58d6a..dbcd0d83f9b 100644
--- a/extra/mariabackup/xtrabackup.h
+++ b/extra/mariabackup/xtrabackup.h
@@ -69,6 +69,7 @@ extern char		*xtrabackup_incremental_dir;
 extern char		*xtrabackup_incremental_basedir;
 extern char		*innobase_data_home_dir;
 extern char		*innobase_buffer_pool_filename;
+extern char		*buffer_pool_filename;
 extern char		*xb_plugin_dir;
 extern char		*xb_rocksdb_datadir;
 extern my_bool	xb_backup_rocksdb;
@@ -164,6 +165,7 @@ extern uint		opt_lock_wait_timeout;
 extern uint		opt_lock_wait_threshold;
 extern uint		opt_debug_sleep_before_unlock;
 extern uint		opt_safe_slave_backup_timeout;
+extern uint		opt_max_binlogs;
 
 extern const char	*opt_history;