Save and clear run context before executing a stored function or trigger and restore it afterwards.

This allows us to use statement replication with functions and triggers
The following things are fixed with this patch:
- NOW() and automatic timestamps takes the value from the main event for functions and triggers (which allows these to replicate with statement level logging)
- No side effects for triggers or functions with auto-increment values(), last_insert_id(), rand() or found_rows()
- Triggers can't return result sets

Fixes bugs:
#12480: NOW() is not constant in a trigger
#12481: Using NOW() in a stored function breaks statement based replication
#12482: Triggers has side effects with auto_increment values
#11587: trigger causes lost connection error


mysql-test/r/trigger.result:
  Added test fpr big
mysql-test/t/sp-error.test:
  Changed error message numbers
mysql-test/t/trigger.test:
  Added test for trigger returning result (#11587)
sql/item_func.cc:
  Store the first used seed value for RAND() value.
  (This makes rand() replicatable in functions and triggers)
  Save and clear run context before executing a stored function and restore it afterwards.
  This removes side effects of stored functions for RAND(), auto-increment values and NOW() and makes most stored function replicatable
sql/share/errmsg.txt:
  Reuse error message also for triggers
sql/sp_head.cc:
  If in function or trigger, don't change value of NOW()
  (This allows us to use statement replication with functions that directly or indirectly uses timestamps)
sql/sql_class.cc:
  Added framework for storing and retrieving run context while exceuting triggers or stored functions.
sql/sql_class.h:
  Added framework for storing and retrieving run context while exceuting triggers or stored functions.
sql/sql_parse.cc:
  If in function or trigger, don't change value of NOW()
  (This allows us to use statement replication with functions that directly or indirectly uses timestamps)
sql/sql_trigger.cc:
  Moved process_triggers function from sql_trigger.h
  Use reset/restore sub_statement_state while executing triggers to avoid side effects and make them replicatable
sql/sql_trigger.h:
  Moved process_triggers function from sql_trigger.h
  Use reset/restore sub_statement_state while executing triggers to avoid side effects and make them replicatable
sql/sql_yacc.yy:
  Give error message if trigger can return a result set (Bug #11587)
tests/fork_big2.pl:
  Removed return from end of lines
mysql-test/r/rpl_trigger.result:
  New BitKeeper file ``mysql-test/r/rpl_trigger.result''
mysql-test/t/rpl_trigger.test:
  New BitKeeper file ``mysql-test/t/rpl_trigger.test''

sql/sql_class.cc

@@ -174,7 +174,7 @@ THD::THD()
   :Statement(CONVENTIONAL_EXECUTION, 0, ALLOC_ROOT_MIN_BLOCK_SIZE, 0),
    Open_tables_state(refresh_version),
    lock_id(&main_lock_id),
-   user_time(0), in_sub_stmt(FALSE), global_read_lock(0), is_fatal_error(0),
+   user_time(0), in_sub_stmt(0), global_read_lock(0), is_fatal_error(0),
    rand_used(0), time_zone_used(0),
    last_insert_id_used(0), insert_id_used(0), clear_next_insert_id(0),
    in_lock_tables(0), bootstrap(0), derived_tables_processing(FALSE),
@@ -1836,3 +1836,85 @@ void THD::restore_backup_open_tables_state(Open_tables_state *backup)
   set_open_tables_state(backup);
   DBUG_VOID_RETURN;
 }
+
+
+/****************************************************************************
+  Handling of statement states in functions and triggers.
+
+  This is used to ensure that the function/trigger gets a clean state
+  to work with and does not cause any side effects of the calling statement.
+
+  It also allows most stored functions and triggers to replicate even
+  if they are used items that would normally be stored in the binary
+  replication (like last_insert_id() etc...)
+
+  The following things is done
+  - Disable binary logging for the duration of the statement
+  - Disable multi-result-sets for the duration of the statement
+  - Value of last_insert_id() is reset and restored
+  - Value set by 'SET INSERT_ID=#' is reset and restored
+  - Value for found_rows() is reset and restored
+  - examined_row_count is added to the total
+  - cuted_fields is added to the total
+
+  NOTES:
+    Seed for random() is saved for the first! usage of RAND()
+    We reset examined_row_count and cuted_fields and add these to the
+    result to ensure that if we have a bug that would reset these within
+    a function, we are not loosing any rows from the main statement.
+****************************************************************************/
+
+void THD::reset_sub_statement_state(Sub_statement_state *backup,
+                                    uint new_state)
+{
+  backup->options=         options;
+  backup->in_sub_stmt=     in_sub_stmt;
+  backup->no_send_ok=      net.no_send_ok;
+  backup->enable_slow_log= enable_slow_log;
+  backup->last_insert_id=  last_insert_id;
+  backup->next_insert_id=  next_insert_id;
+  backup->insert_id_used=  insert_id_used;
+  backup->limit_found_rows= limit_found_rows;
+  backup->examined_row_count= examined_row_count;
+  backup->sent_row_count=   sent_row_count;
+  backup->cuted_fields=     cuted_fields;
+  backup->client_capabilities= client_capabilities;
+
+  options&= ~OPTION_BIN_LOG;
+  /* Disable result sets */
+  client_capabilities &= ~CLIENT_MULTI_RESULTS;
+  in_sub_stmt|= new_state;
+  last_insert_id= 0;
+  next_insert_id= 0;
+  insert_id_used= 0;
+  examined_row_count= 0;
+  sent_row_count= 0;
+  cuted_fields= 0;
+
+#ifndef EMBEDDED_LIBRARY
+  /* Surpress OK packets in case if we will execute statements */
+  net.no_send_ok= TRUE;
+#endif
+}
+
+
+void THD::restore_sub_statement_state(Sub_statement_state *backup)
+{
+  options=          backup->options;
+  in_sub_stmt=      backup->in_sub_stmt;
+  net.no_send_ok=   backup->no_send_ok;
+  enable_slow_log=  backup->enable_slow_log;
+  last_insert_id=   backup->last_insert_id;
+  next_insert_id=   backup->next_insert_id;
+  insert_id_used=   backup->insert_id_used;
+  limit_found_rows= backup->limit_found_rows;
+  sent_row_count=   backup->sent_row_count;
+  client_capabilities= backup->client_capabilities;
+
+  /*
+    The following is added to the old values as we are interested in the
+    total complexity of the query
+  */
+  examined_row_count+= backup->examined_row_count;
+  cuted_fields+=       backup->cuted_fields;
+}