MDEV-36087 Check for existence of the new Options JSON field in mysql.servers

This fixes server startup segv introduced in MDEV-34716
d2eba35 when upgrading from server
versions lower than 11.7.

Also construct the JSON Options column when upgrading from a version
without the column.

Author: mariadb-YuchenPei

scripts/mariadb_system_tables_fix.sql

@@ -903,8 +903,18 @@ ALTER TABLE servers
   MODIFY Socket char(108) NOT NULL DEFAULT '';
 
 # MDEV-34716 Allow arbitrary options in CREATE SERVER
+# Check existence of the Options column
+SET @hadOptions:=0;
+SELECT @hadOptions:=1 FROM servers WHERE options IS NOT NULL;
 ALTER TABLE servers
   ADD Options JSON NOT NULL DEFAULT '{}' CHECK(JSON_VALID(Options));
 # Ensure the collation is utf8mb4_bin (default for JSON)
 ALTER TABLE servers
   MODIFY Options JSON  NOT NULL DEFAULT '{}' CHECK(JSON_VALID(Options));
+# If the Options column did not exist, convert to the Options
+UPDATE servers SET Options = JSON_INSERT(Options, '$.host', Host) WHERE Host <> '' AND @hadOptions = 0;
+UPDATE servers SET Options = JSON_INSERT(Options, '$.database', Db) WHERE Db <> '' AND @hadOptions = 0;
+UPDATE servers SET Options = JSON_INSERT(Options, '$.username', Username) WHERE Username <> '' AND @hadOptions = 0;
+UPDATE servers SET Options = JSON_INSERT(Options, '$.port', CAST(Port AS VARCHAR(5))) WHERE @hadOptions = 0;
+UPDATE servers SET Options = JSON_INSERT(Options, '$.socket', Socket) WHERE Socket <> '' AND @hadOptions = 0;
+UPDATE servers SET Options = JSON_INSERT(Options, '$.owner', Owner) WHERE Owner <> '' AND @hadOptions = 0;

sql/sql_servers.cc

@@ -473,7 +473,7 @@ get_server_from_table_to_cache(TABLE *table)
   server->scheme= ptr ? ptr : blank;
   ptr= get_field(&mem, table->field[8]);
   server->owner= ptr ? ptr : blank;
-  ptr= get_field(&mem, table->field[9]);
+  ptr= table->field[9] ? get_field(&mem, table->field[9]) : NULL;
   server->option_list= NULL;
   if (ptr && parse_server_options_json(server, ptr))
     DBUG_RETURN(TRUE);