BUG#27779: Slave cannot read old rows log events.

Problem: Replication fails when master is mysql-5.1-wl2325-5.0-drop6 and
slave is mysql-5.1-new-rpl. The reason is that, in
mysql-5.1-wl2325-5.0-drop6, the event type id's were different than in
mysql-5.1-new-rpl.
Fix (in mysql-5.1-new-rpl):
 (1) detect that the server that generated the events uses the old
format, by checking the server version of the format_description_log_event
This patch recognizes mysql-5.1-wl2325-5.0-drop6p13-alpha,
mysql-5.1-wl2325-5.0-drop6, mysql-5.1-wl2325-5.0, mysql-5.1-wl2325-no-dd.
 (2) if the generating server is old, map old event types to new event
types using a permutation array.

I've also added a test case which reads binlogs for four different
versions.

1 files changed, 5 insertions, 1 deletions

diff --git a/sql/log_event.h b/sql/log_event.h
index 4a75f330203..31c1ab7173a 100644
--- a/sql/log_event.h
+++ b/sql/log_event.h
@@ -2106,12 +2106,16 @@ public:
   /* The list of post-headers' lengthes */
   uint8 *post_header_len;
   uchar server_version_split[3];
+  const uint8 *event_type_permutation;
 
   Format_description_log_event(uint8 binlog_ver, const char* server_ver=0);
   Format_description_log_event(const char* buf, uint event_len,
                                const Format_description_log_event
                                *description_event);
-  ~Format_description_log_event() { my_free((uchar*)post_header_len, MYF(0)); }
+  ~Format_description_log_event()
+  {
+    my_free((uchar*)post_header_len, MYF(MY_ALLOW_ZERO_PTR));
+  }
   Log_event_type get_type_code() { return FORMAT_DESCRIPTION_EVENT;}
 #ifndef MYSQL_CLIENT
   bool write(IO_CACHE* file);