The following statements support the CURRENT_USER() where a user is needed.

DROP USER 
RENAME USER CURRENT_USER() ...
GRANT ... TO CURRENT_USER()
REVOKE ... FROM CURRENT_USER()
ALTER DEFINER = CURRENT_USER() EVENTbut, When these statements are binlogged, CURRENT_USER() just is binlogged
as 'CURRENT_USER()', it is not expanded to the real user name. When slave 
executes the log event, 'CURRENT_USER()' is expand to the user of slave 
SQL thread, but SQL thread's user name always NULL. This breaks the replication.

After this patch, session's user will be written into query log events 
if these statements call CURREN_USER() or 'ALTER EVENT' does not assign a definer.


mysql-test/include/diff_tables.inc:
  Expend its abilities.
  Now it can diff not only in sessions of 'master' and 'slave', but 
  other sessions as well.
sql/log_event.cc:
  session's user will be written into Query_log_event, if is_current_user_used() is TRUE.
  On slave SQL thread, Only thd->invoker is written into Query_log_event,
  if it exists.
sql/sql_acl.cc:
  On slave SQL thread, grantor should copy from thd->invoker, if it exists
sql/sql_class.h:
  On slave SQL thread, thd->invoker is used to store the applying event's
  invoker.

1 files changed, 64 insertions, 1 deletions

diff --git a/sql/log_event.cc b/sql/log_event.cc
index d53f13e0b6b..0e4d4bd512b 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -2307,6 +2307,53 @@ bool Query_log_event::write(IO_CACHE* file)
     start+= 4;
   }
 
+  if (thd && thd->is_current_user_used())
+  {
+    LEX_STRING user;
+    LEX_STRING host;
+    memset(&user, 0, sizeof(user));
+    memset(&host, 0, sizeof(host));
+
+    if (thd->slave_thread && thd->has_invoker())
+    {
+      /* user will be null, if master is older than this patch */
+      user= thd->get_invoker_user();
+      host= thd->get_invoker_host();
+    }
+    else if (thd->security_ctx->priv_user)
+    {
+      Security_context *ctx= thd->security_ctx;
+
+      user.length= strlen(ctx->priv_user);
+      user.str= ctx->priv_user;
+      if (ctx->priv_host[0] != '\0')
+      {
+        host.str= ctx->priv_host;
+        host.length= strlen(ctx->priv_host);
+      }
+    }
+
+    if (user.length > 0)
+    {
+      *start++= Q_INVOKER;
+
+      /*
+        Store user length and user. The max length of use is 16, so 1 byte is
+        enough to store the user's length.
+       */
+      *start++= (uchar)user.length;
+      memcpy(start, user.str, user.length);
+      start+= user.length;
+
+      /*
+        Store host length and host. The max length of host is 60, so 1 byte is
+        enough to store the host's length.
+       */
+      *start++= (uchar)host.length;
+      memcpy(start, host.str, host.length);
+      start+= host.length;
+    }
+  }
   /*
     NOTE: When adding new status vars, please don't forget to update
     the MAX_SIZE_LOG_EVENT_STATUS in log_event.h and update the function
@@ -2575,6 +2622,8 @@ Query_log_event::Query_log_event(const char* buf, uint event_len,
   bool catalog_nz= 1;
   DBUG_ENTER("Query_log_event::Query_log_event(char*,...)");
 
+  memset(&user, 0, sizeof(user));
+  memset(&host, 0, sizeof(host));
   common_header_len= description_event->common_header_len;
   post_header_len= description_event->post_header_len[event_type-1];
   DBUG_PRINT("info",("event_len: %u  common_header_len: %d  post_header_len: %d",
@@ -2729,6 +2778,20 @@ Query_log_event::Query_log_event(const char* buf, uint event_len,
       data_written= master_data_written= uint4korr(pos);
       pos+= 4;
       break;
+    case Q_INVOKER:
+    {
+      CHECK_SPACE(pos, end, 1);
+      user.length= *pos++;
+      CHECK_SPACE(pos, end, user.length);
+      user.str= my_strndup((const char *)pos, user.length, MYF(0));
+      pos+= user.length;
+
+      CHECK_SPACE(pos, end, 1);
+      host.length= *pos++;
+      CHECK_SPACE(pos, end, host.length);
+      host.str= my_strndup((const char *)pos, host.length, MYF(0));
+      pos+= host.length;
+    }
     default:
       /* That's why you must write status vars in growing order of code */
       DBUG_PRINT("info",("Query_log_event has unknown status vars (first has\
@@ -3178,7 +3241,7 @@ int Query_log_event::do_apply_event(Relay_log_info const *rli,
         thd->variables.collation_database= thd->db_charset;
       
       thd->table_map_for_update= (table_map)table_map_for_update;
-      
+      thd->set_invoker(&user, &host);
       /* Execute the query (note that we bypass dispatch_command()) */
       const char* found_semicolon= NULL;
       mysql_parse(thd, thd->query(), thd->query_length(), &found_semicolon);