Replication: various small fixes specific to the new binlog format of 5.0

(including one which may explain autobuild's failure of yesterday)


client/mysqlbinlog.cc:
  - In mysqlbinlog, we should not reset the Format event when we see Rotate. If a binlog started with a Format event, it is not going to switch later to 4.0 format.
  I had already did the same fix in Rotate_log_event::exec_event() in replication.
  - Fix for a merge bug.
sql/log_event.cc:
  An event with an uninited catalog (read from a 4.x server) is not the same as an event with a NULL catalog
  (5.0 server which did not specify catalog), the difference is that they are not in the same format;
  so I introduce a way to know if the catalog has been inited or not. This fixes a rpl_trunc_binlog failure
  I had.
  When we leave Load_log_event::exec_event(), we must reset thd->catalog to 0, like we already do
  in Query_log_event::exec_event(). This fixes a Valgrind error which popped in rpl_charset (which may
  be what caused autobuild to crash yesterday).
  And a fix for event's parsing (the position was always computed right because start_dup==end is always true
  and will until we add new string members to Query_log_event.
sql/log_event.h:
  catalog_len changed from uint to int to allow -1, which means "not inited"
  (I preferred to do it like this rather than create a new bool var Query_log_event::catalog_inited
  like we have in Query_log_event::sql_mode_inited; that's because catalog will not use the whole range of int,
  so it's allowed to pick -1 as a special value and have only one var.
sql/slave.cc:
  comments

1 files changed, 5 insertions, 2 deletions

diff --git a/sql/slave.cc b/sql/slave.cc
index 8899635e2c6..8843e1561ec 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -372,7 +372,7 @@ int init_relay_log_pos(RELAY_LOG_INFO* rli,const char* log,
           (starting from position 4):
           Format_desc (of slave)
           Rotate (of master)
-          Format_desc (of slave)
+          Format_desc (of master)
           So the Format_desc which really describes the rest of the relay log is
           the 3rd event (it can't be further than that, because we rotate the
           relay log when we queue a Rotate event from the master).
@@ -3873,7 +3873,10 @@ static int process_io_rotate(MASTER_INFO *mi, Rotate_log_event *rev)
     mi->rli.relay_log.description_event_for_queue= new
       Format_description_log_event(3);
   }
-
+  /*
+    Rotate the relay log makes binlog format detection easier (at next slave
+    start or mysqlbinlog)
+  */
   rotate_relay_log(mi); /* will take the right mutexes */
   DBUG_RETURN(0);
 }