MDEV-27184 Assertion `(old_top == initial_top (av) && old_size == 0) ||...

MDEV-27184 Assertion `(old_top == initial_top (av) && old_size == 0) || ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) && ((unsigned long) old_end & (pagesize - 1)) == 0)' failed, Assertion `str.alloced_length() >= str.length() + data_len' failed

Spider crashes on a query that inserts some rows including float.
This is because Spider allocates a string of insufficient length.

storage/spider/mysql-test/spider/bugfix/r/mdev_27184.result

+#
+# MDEV-27184 Assertion `(old_top == initial_top (av) && old_size == 0) ||
+# ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) &&
+# ((unsigned long) old_end & (pagesize - 1)) == 0)' failed,
+# Assertion `str.alloced_length() >= str.length() + data_len' failed
+#
+for master_1
+for child2
+for child3
+connection master_1;
+CREATE DATABASE auto_test_remote;
+USE auto_test_remote;
+CREATE TABLE tbl_a (a FLOAT) ENGINE=SPIDER;
+INSERT INTO tbl_a VALUES
+(0xF5A7),(0xF5A8),(0xF5A9),(0xF5AA),(0xF5AB),(0xF5AC),(0xF5AD),(0xF5AE),
+(0xF5A7),(0xF5A8),(0xF5A9),(0xF5AA),(0xF5AB),(0xF5AC),(0xF5AD),(0xF5AE);
+ERROR HY000: Unable to connect to foreign data source: localhost
+DROP DATABASE auto_test_remote;
+for master_1
+for child2
+for child3

storage/spider/mysql-test/spider/bugfix/t/mdev_27184.cnf

+!include include/default_mysqld.cnf
+!include ../my_1_1.cnf

storage/spider/mysql-test/spider/bugfix/t/mdev_27184.test

+--echo #
+--echo # MDEV-27184 Assertion `(old_top == initial_top (av) && old_size == 0) ||
+--echo # ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) &&
+--echo # ((unsigned long) old_end & (pagesize - 1)) == 0)' failed,
+--echo # Assertion `str.alloced_length() >= str.length() + data_len' failed
+--echo #
+
+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+
+--connection master_1
+CREATE DATABASE auto_test_remote;
+USE auto_test_remote;
+
+CREATE TABLE tbl_a (a FLOAT) ENGINE=SPIDER;
+
+--error ER_CONNECT_TO_FOREIGN_DATA_SOURCE
+INSERT INTO tbl_a VALUES
+    (0xF5A7),(0xF5A8),(0xF5A9),(0xF5AA),(0xF5AB),(0xF5AC),(0xF5AD),(0xF5AE),
+    (0xF5A7),(0xF5A8),(0xF5A9),(0xF5AA),(0xF5AB),(0xF5AC),(0xF5AD),(0xF5AE);
+
+DROP DATABASE auto_test_remote;
+
+--disable_query_log
+--disable_result_log
+--source ../../t/test_deinit.inc
+--enable_result_log
+--enable_query_log

storage/spider/spd_db_mysql.cc

@@ -4243,7 +4243,7 @@ int spider_db_mariadb_util::append_column_value(
   } else if (float_value)
   {
     if (str->reserve(SPIDER_SQL_CAST_LEN + ptr->length() +
-      SPIDER_SQL_AS_FLOAT_LEN, SPIDER_SQL_CLOSE_PAREN_LEN))
+                     SPIDER_SQL_AS_FLOAT_LEN + SPIDER_SQL_CLOSE_PAREN_LEN))
     {
       DBUG_RETURN(HA_ERR_OUT_OF_MEM);
     }