BUG#55387: binlog.binlog_tmp_table crashes the server

           sporadically

There are two problems:

1. When closing temporary tables, during the THD clean up - and
   after the session connection was already closed, there is a
   chance we can push an error into the THD diagnostics area, if
   the writing of the implicit DROP event to the binary log fails
   for some reason. As a consequence an assertion can be
   triggered, because at that point the diagnostics area is
   already set.

2. Using push_warning with MYSQL_ERROR::WARN_LEVEL_ERROR is a 
   bug.

Given that close_temporary_tables is mostly called from
THD::cleanup - ie, with the session already closed, we fix
problem #1 by allowing the diagnostics area to be
overwritten. There is one other place in the code that calls
close_temporary_tables - while applying Start_log_event_v3. To
cover that case, we make close_temporary_tables to return the
error, thus, propagating upwards in the stack.

To fix problem #2, we replace push_warning with sql_print_error.

sql/log_event.cc:
  Added handling of error returned by close_temporary_tables to
  Start_log_event_v3::do_apply_event.
sql/sql_base.cc:
  Three changes to close_temporary_tables:
  1. it returns a boolean now (instead of void)
  2. it uses sql_print_error instead of push_warning when writing to
     binary log fails
  3. we set can_overwrite_status before writing to the binary log,
     thence not risking triggering an assertion by any other push
     into diagnostics area happening inside mysql_bin_log.write.
sql/sql_base.h:
  Changed the interface of close_temporary_tables so that it returns
  bool instead of void.

sql/log_event.cc

@@ -3719,6 +3719,7 @@ bool Start_log_event_v3::write(IO_CACHE* file)
 int Start_log_event_v3::do_apply_event(Relay_log_info const *rli)
 {
   DBUG_ENTER("Start_log_event_v3::do_apply_event");
+  int error= 0;
   switch (binlog_version)
   {
   case 3:
@@ -3731,7 +3732,7 @@ int Start_log_event_v3::do_apply_event(Relay_log_info const *rli)
     */
     if (created)
     {
-      close_temporary_tables(thd);
+      error= close_temporary_tables(thd);
       cleanup_load_tmpdir();
     }
     else
@@ -3759,7 +3760,7 @@ int Start_log_event_v3::do_apply_event(Relay_log_info const *rli)
         Can distinguish, based on the value of 'created': this event was
         generated at master startup.
       */
-      close_temporary_tables(thd);
+      error= close_temporary_tables(thd);
     }
     /*
       Otherwise, can't distinguish a Start_log_event generated at
@@ -3771,7 +3772,7 @@ int Start_log_event_v3::do_apply_event(Relay_log_info const *rli)
     /* this case is impossible */
     DBUG_RETURN(1);
   }
-  DBUG_RETURN(0);
+  DBUG_RETURN(error);
 }
 #endif /* defined(HAVE_REPLICATION) && !defined(MYSQL_CLIENT) */
 

sql/sql_base.cc

@@ -1634,7 +1634,7 @@ static inline uint  tmpkeyval(THD *thd, TABLE *table)
   creates one DROP TEMPORARY TABLE binlog event for each pseudo-thread 
 */
 
-void close_temporary_tables(THD *thd)
+bool close_temporary_tables(THD *thd)
 {
   DBUG_ENTER("close_temporary_tables");
   TABLE *table;
@@ -1642,9 +1642,10 @@ void close_temporary_tables(THD *thd)
   TABLE *prev_table;
   /* Assume thd->variables.option_bits has OPTION_QUOTE_SHOW_CREATE */
   bool was_quote_show= TRUE;
+  bool error= 0;
 
   if (!thd->temporary_tables)
-    DBUG_VOID_RETURN;
+    DBUG_RETURN(FALSE);
 
   if (!mysql_bin_log.is_open())
   {
@@ -1655,7 +1656,7 @@ void close_temporary_tables(THD *thd)
       close_temporary(table, 1, 1);
     }
     thd->temporary_tables= 0;
-    DBUG_VOID_RETURN;
+    DBUG_RETURN(FALSE);
   }
 
   /* Better add "if exists", in case a RESET MASTER has been done */
@@ -1754,11 +1755,27 @@ void close_temporary_tables(THD *thd)
       qinfo.db= db.ptr();
       qinfo.db_len= db.length();
       thd->variables.character_set_client= cs_save;
-      if (mysql_bin_log.write(&qinfo))
+
+      thd->stmt_da->can_overwrite_status= TRUE;
+      if ((error= (mysql_bin_log.write(&qinfo) || error)))
       {
-        push_warning(thd, MYSQL_ERROR::WARN_LEVEL_ERROR, MYF(0),
-                     "Failed to write the DROP statement for temporary tables to binary log");
+        /*
+          If we're here following THD::cleanup, thence the connection
+          has been closed already. So lets print a message to the
+          error log instead of pushing yet another error into the
+          stmt_da.
+
+          Also, we keep the error flag so that we propagate the error
+          up in the stack. This way, if we're the SQL thread we notice
+          that close_temporary_tables failed. (Actually, the SQL
+          thread only calls close_temporary_tables while applying old
+          Start_log_event_v3 events.)
+        */
+        sql_print_error("Failed to write the DROP statement for "
+                        "temporary tables to binary log");
       }
+      thd->stmt_da->can_overwrite_status= FALSE;
+
       thd->variables.pseudo_thread_id= save_pseudo_thread_id;
       thd->thread_specific_used= save_thread_specific_used;
     }
@@ -1771,7 +1788,8 @@ void close_temporary_tables(THD *thd)
   if (!was_quote_show)
     thd->variables.option_bits&= ~OPTION_QUOTE_SHOW_CREATE; /* restore option */
   thd->temporary_tables=0;
-  DBUG_VOID_RETURN;
+
+  DBUG_RETURN(error);
 }
 
 /*

sql/sql_base.h

@@ -222,7 +222,7 @@ int decide_logging_format(THD *thd, TABLE_LIST *tables);
 void free_io_cache(TABLE *entry);
 void intern_close_table(TABLE *entry);
 bool close_thread_table(THD *thd, TABLE **table_ptr);
-void close_temporary_tables(THD *thd);
+bool close_temporary_tables(THD *thd);
 TABLE_LIST *unique_table(THD *thd, TABLE_LIST *table, TABLE_LIST *table_list,
                          bool check_alias);
 int drop_temporary_table(THD *thd, TABLE_LIST *table_list);