MDEV-5273 Prepared statement doesn't return metadata after prepare.

        SHOW MASTER STATUS fixed.

Author: Alexey Botchkov

sql/slave.h

@@ -211,6 +211,7 @@ void show_master_info_get_fields(THD *thd, List<Item> *field_list,
                                      bool full, size_t gtid_pos_length);
 bool show_master_info(THD* thd, Master_info* mi, bool full);
 bool show_all_master_info(THD* thd);
+void show_binlog_info_get_fields(THD *thd, List<Item> *field_list);
 bool show_binlog_info(THD* thd);
 bool rpl_master_has_bug(const Relay_log_info *rli, uint bug_id, bool report,
                         bool (*pred)(const void *), const void *param);

sql/sql_prepare.cc

@@ -1916,6 +1916,29 @@ static bool mysql_test_show_slave_status(Prepared_statement *stmt)
 }
 
 
+/**
+  Validate and prepare for execution SHOW MASTER STATUS statement.
+
+  @param stmt               prepared statement
+
+  @retval
+    FALSE             success
+  @retval
+    TRUE              error, error message is set in THD
+*/
+
+static bool mysql_test_show_master_status(Prepared_statement *stmt)
+{
+  DBUG_ENTER("mysql_test_show_master_status");
+  THD *thd= stmt->thd;
+  List<Item> fields;
+
+  show_binlog_info_get_fields(thd, &fields);
+    
+  DBUG_RETURN(send_stmt_metadata(thd, stmt, &fields));
+}
+
+
 /**
   @brief Validate and prepare for execution CREATE VIEW statement
 
@@ -2277,6 +2300,13 @@ static bool check_prepared_statement(Prepared_statement *stmt)
       DBUG_RETURN(FALSE);
     }
     break;
+  case SQLCOM_SHOW_MASTER_STAT:
+    if (!(res= mysql_test_show_master_status(stmt)))
+    {
+      /* Statement and field info has already been sent */
+      DBUG_RETURN(FALSE);
+    }
+    break;
   case SQLCOM_CREATE_VIEW:
     if (lex->create_view_mode == VIEW_ALTER)
     {

sql/sql_repl.cc

@@ -4088,6 +4088,25 @@ bool mysql_show_binlog_events(THD* thd)
 }
 
 
+void show_binlog_info_get_fields(THD *thd, List<Item> *field_list)
+{
+  MEM_ROOT *mem_root= thd->mem_root;
+  field_list->push_back(new (mem_root)
+                        Item_empty_string(thd, "File", FN_REFLEN),
+                        mem_root);
+  field_list->push_back(new (mem_root)
+                        Item_return_int(thd, "Position", 20,
+                                        MYSQL_TYPE_LONGLONG),
+                        mem_root);
+  field_list->push_back(new (mem_root)
+                        Item_empty_string(thd, "Binlog_Do_DB", 255),
+                        mem_root);
+  field_list->push_back(new (mem_root)
+                        Item_empty_string(thd, "Binlog_Ignore_DB", 255),
+                        mem_root);
+}
+
+
 /**
   Execute a SHOW MASTER STATUS statement.
 
@@ -4100,23 +4119,10 @@ bool mysql_show_binlog_events(THD* thd)
 bool show_binlog_info(THD* thd)
 {
   Protocol *protocol= thd->protocol;
-  MEM_ROOT *mem_root= thd->mem_root;
   DBUG_ENTER("show_binlog_info");
 
   List<Item> field_list;
-  field_list.push_back(new (mem_root)
-                       Item_empty_string(thd, "File", FN_REFLEN),
-                       mem_root);
-  field_list.push_back(new (mem_root)
-                       Item_return_int(thd, "Position", 20,
-                                       MYSQL_TYPE_LONGLONG),
-                       mem_root);
-  field_list.push_back(new (mem_root)
-                       Item_empty_string(thd, "Binlog_Do_DB", 255),
-                       mem_root);
-  field_list.push_back(new (mem_root)
-                       Item_empty_string(thd, "Binlog_Ignore_DB", 255),
-                       mem_root);
+  show_binlog_info_get_fields(thd, &field_list);
 
   if (protocol->send_result_set_metadata(&field_list,
                             Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))

tests/mysql_client_test.c

@@ -450,6 +450,13 @@ static void test_prepare_simple()
   DIE_UNLESS(mysql_stmt_field_count(stmt) == 47);
   mysql_stmt_close(stmt);
 
+  /* show master status */
+  strmov(query, "SHOW MASTER STATUS");
+  stmt= mysql_simple_prepare(mysql, query);
+  check_stmt(stmt);
+  DIE_UNLESS(mysql_stmt_field_count(stmt) == 4);
+  mysql_stmt_close(stmt);
+
   /* now fetch the results ..*/
   rc= mysql_commit(mysql);
   myquery(rc);