Fix Bug#17600: Invalid data logged into mysql.slow_log

Recommit with post-review fixes.

mysql-test/r/log_tables.result

@@ -64,3 +64,11 @@ TIMESTAMP	root[root] @ localhost []	2	1	Query	create table bug16905 (s char(15)
 TIMESTAMP	root[root] @ localhost []	2	1	Query	insert into bug16905 values ('новое')
 TIMESTAMP	root[root] @ localhost []	2	1	Query	select * from mysql.general_log
 drop table bug16905;
+truncate table mysql.slow_log;
+set session long_query_time=1;
+select sleep(2);
+sleep(2)
+0
+select * from mysql.slow_log;
+start_time	user_host	query_time	lock_time	rows_sent	rows_examined	db	last_insert_id	insert_id	server_id	sql_text
+TIMESTAMP,	root[root] @ localhost []	USER_HOST,	QUERY_TIME	1	0	test	0	0	1	select sleep(2)

mysql-test/t/log_tables-master.opt

+--log-slow-queries

mysql-test/t/log_tables.test

@@ -160,6 +160,16 @@ insert into bug16905 values ('новое');
 select * from mysql.general_log;
 drop table bug16905;
 
+#
+# Bug #17600: Invalid data logged into mysql.slow_log
+#
+
+truncate table mysql.slow_log;
+set session long_query_time=1;
+select sleep(2);
+--replace_column 1 TIMESTAMP, 3 USER_HOST, 4 QUERY_TIME
+select * from mysql.slow_log;
+
 # kill all connections
 disconnect con1;
 disconnect con2;

sql/log.cc

@@ -288,7 +288,7 @@ void Log_to_csv_event_handler::cleanup()
   Log command to the general log table
 
   SYNOPSIS
-    log_general_to_csv()
+    log_general()
 
     event_time        command start timestamp
     user_host         the pointer to the string with user@host info
@@ -322,18 +322,32 @@ bool Log_to_csv_event_handler::
   if (unlikely(!logger.is_log_tables_initialized))
     return FALSE;
 
+  /*
+    NOTE: we do not call restore_record() here, as all fields are
+    filled by the Logger (=> no need to load default ones).
+  */
+
   /* log table entries are not replicated at the moment */
   tmp_disable_binlog(current_thd);
 
+  /* Set current time. Required for CURRENT_TIMESTAMP to work */
   general_log_thd->start_time= event_time;
-  /* set default value (which is CURRENT_TIMESTAMP) */
-  table->field[0]->set_null();
+
+  /*
+    We do not set a value for table->field[0], as it will use
+    default value (which is CURRENT_TIMESTAMP).
+  */
 
   table->field[1]->store(user_host, user_host_len, client_cs);
+  table->field[1]->set_notnull();
   table->field[2]->store((longlong) thread_id);
+  table->field[2]->set_notnull();
   table->field[3]->store((longlong) server_id);
+  table->field[3]->set_notnull();
   table->field[4]->store(command_type, command_type_len, client_cs);
+  table->field[4]->set_notnull();
   table->field[5]->store(sql_text, sql_text_len, client_cs);
+  table->field[5]->set_notnull();
   table->file->ha_write_row(table->record[0]);
 
   reenable_binlog(current_thd);
@@ -346,7 +360,7 @@ bool Log_to_csv_event_handler::
   Log a query to the slow log table
 
   SYNOPSIS
-    log_slow_to_csv()
+    log_slow()
     thd               THD of the query
     current_time      current timestamp
     query_start_arg   command start timestamp
@@ -381,7 +395,7 @@ bool Log_to_csv_event_handler::
   TABLE *table= slow_log.table;
   CHARSET_INFO *client_cs= thd->variables.character_set_client;
 
-  DBUG_ENTER("log_slow_to_csv");
+  DBUG_ENTER("log_slow");
 
   /* below should never happen */
   if (unlikely(!logger.is_log_tables_initialized))
@@ -392,12 +406,15 @@ bool Log_to_csv_event_handler::
 
   /*
      Set start time for CURRENT_TIMESTAMP to the start of the query.
-     This will be default value for the field
+     This will be default value for the field[0]
   */
   slow_log_thd->start_time= query_start_arg;
+  restore_record(table, s->default_values);    // Get empty record
 
-  /* set default value (which is CURRENT_TIMESTAMP) */
-  table->field[0]->set_null();
+  /*
+    We do not set a value for table->field[0], as it will use
+    default value.
+  */
 
   /* store the value */
   table->field[1]->store(user_host, user_host_len, client_cs);
@@ -421,24 +438,28 @@ bool Log_to_csv_event_handler::
     table->field[5]->set_null();
   }
 
+  /* fill database field */
   if (thd->db)
-    /* fill database field */
+  {
     table->field[6]->store(thd->db, thd->db_length, client_cs);
-  else
-    table->field[6]->set_null();
+    table->field[6]->set_notnull();
+  }
 
   if (thd->last_insert_id_used)
+  {
     table->field[7]->store((longlong) thd->current_insert_id);
-  else
-    table->field[7]->set_null();
+    table->field[7]->set_notnull();
+  }
 
   /* set value if we do an insert on autoincrement column */
   if (thd->insert_id_used)
+  {
     table->field[8]->store((longlong) thd->last_insert_id);
-  else
-    table->field[8]->set_null();
+    table->field[8]->set_notnull();
+  }
 
   table->field[9]->store((longlong) server_id);
+  table->field[9]->set_notnull();
 
   /* sql_text */
   table->field[10]->store(sql_text,sql_text_len, client_cs);

storage/csv/ha_tina.cc

@@ -351,9 +351,20 @@ int ha_tina::encode_quote(byte *buf)
     const char *ptr;
     const char *end_ptr;
 
-    (*field)->val_str(&attribute,&attribute);
-    ptr= attribute.ptr();
-    end_ptr= attribute.length() + ptr;
+    /*
+      Write an empty string to the buffer in case of a NULL value.
+      Basically this is a safety check, as no one ensures that the
+      field content is cleaned up every time we use Field::set_null()
+      in the code.
+    */
+    if ((*field)->is_null())
+      ptr= end_ptr= 0;
+    else
+    {
+      (*field)->val_str(&attribute,&attribute);
+      ptr= attribute.ptr();
+      end_ptr= attribute.length() + ptr;
+    }
 
     buffer.append('"');