Bug#27171 mysqlbinlog produces different output depends from option -R

Server starts any binlog dump from Format_description_log_event,
this shifted all offset calculations in mysqlbinlog and made it
to stop the dump earlier than --stop-position. Now mysqlbinlog
takes Format_description_log_event into account


mysql-test/r/mysqlbinlog2.result:
  Bug#27171 mysqlbinlog produces different output depends from option -R
mysql-test/t/mysqlbinlog2.test:
  Bug#27171 mysqlbinlog produces different output depends from option -R

client/mysqlbinlog.cc

@@ -1040,7 +1040,7 @@ static int dump_remote_log_entries(PRINT_EVENT_INFO *print_event_info,
   uint logname_len;
   NET* net;
   int error= 0;
-  my_off_t old_off= start_position_mot;
+  my_off_t old_off= min(start_position_mot, BIN_LOG_HEADER_SIZE);
   char fname[FN_REFLEN+1];
   DBUG_ENTER("dump_remote_log_entries");
 
@@ -1192,10 +1192,17 @@ could be out of memory");
       }
     }
     /*
-      Let's adjust offset for remote log as for local log to produce 
-      similar text.
+      Let's adjust offset for remote log as for local log to produce
+      similar text and to have --stop-position to work identically.
+
+      Exception - the server sends Format_description_log_event
+      in the beginning of the dump, and only after it the event from
+      start_position. Let the old_off reflect it.
     */
-    old_off+= len-1;
+    if (old_off < start_position_mot)
+      old_off= start_position_mot;
+    else
+      old_off+= len-1;
   }
 
 err:

mysql-test/r/mysqlbinlog2.result

@@ -122,6 +122,24 @@ DELIMITER ;
 ROLLBACK /* added by mysqlbinlog */;
 /*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
 
+--- start and stop positions ---
+/*!40019 SET @@session.max_insert_delayed_threads=0*/;
+/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
+DELIMITER /*!*/;
+SET INSERT_ID=4/*!*/;
+use test/*!*/;
+SET TIMESTAMP=1579609946/*!*/;
+SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1/*!*/;
+SET @@session.sql_mode=0/*!*/;
+/*!\C latin1 *//*!*/;
+SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8/*!*/;
+insert into t1 values(null, "d")/*!*/;
+SET INSERT_ID=5/*!*/;
+DELIMITER ;
+# End of log file
+ROLLBACK /* added by mysqlbinlog */;
+/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
+
 --- start-datetime --
 /*!40019 SET @@session.max_insert_delayed_threads=0*/;
 /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
@@ -481,6 +499,24 @@ DELIMITER ;
 ROLLBACK /* added by mysqlbinlog */;
 /*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
 
+--- start and stop positions ---
+/*!40019 SET @@session.max_insert_delayed_threads=0*/;
+/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
+DELIMITER /*!*/;
+SET INSERT_ID=4/*!*/;
+use test/*!*/;
+SET TIMESTAMP=1579609946/*!*/;
+SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=1, @@session.unique_checks=1/*!*/;
+SET @@session.sql_mode=0/*!*/;
+/*!\C latin1 *//*!*/;
+SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=8/*!*/;
+insert into t1 values(null, "d")/*!*/;
+SET INSERT_ID=5/*!*/;
+DELIMITER ;
+# End of log file
+ROLLBACK /* added by mysqlbinlog */;
+/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
+
 --- start-datetime --
 /*!40019 SET @@session.max_insert_delayed_threads=0*/;
 /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;

mysql-test/t/mysqlbinlog2.test

@@ -55,6 +55,10 @@ select "--- stop-position --" as "";
 --enable_query_log
 --exec $MYSQL_BINLOG --short-form --stop-position=600 $MYSQLTEST_VARDIR/log/master-bin.000001 
 --disable_query_log
+select "--- start and stop positions ---" as "";
+--enable_query_log
+--exec $MYSQL_BINLOG --short-form --start-position=600 --stop-position 725 $MYSQLTEST_VARDIR/log/master-bin.000001 
+--disable_query_log
 select "--- start-datetime --" as "";
 --enable_query_log
 --exec $MYSQL_BINLOG --short-form "--start-datetime=2020-01-21 15:32:24" $MYSQLTEST_VARDIR/log/master-bin.000001 
@@ -111,6 +115,10 @@ select "--- stop-position --" as "";
 --enable_query_log
 --exec $MYSQL_BINLOG --short-form --stop-position=600 --read-from-remote-server --user=root --host=127.0.0.1 --port=$MASTER_MYPORT master-bin.000001 
 --disable_query_log
+select "--- start and stop positions ---" as "";
+--enable_query_log
+--exec $MYSQL_BINLOG --short-form --start-position=600 --stop-position 725 --read-from-remote-server --user=root --host=127.0.0.1 --port=$MASTER_MYPORT master-bin.000001
+--disable_query_log
 select "--- start-datetime --" as "";
 --enable_query_log
 --exec $MYSQL_BINLOG --short-form "--start-datetime=2020-01-21 15:32:24" --read-from-remote-server --user=root --host=127.0.0.1 --port=$MASTER_MYPORT master-bin.000001