trigger.h

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/*
   Copyright (c) 2013, 2025, Oracle and/or its affiliates.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef TRIGGER_H_INCLUDED
#define TRIGGER_H_INCLUDED
 
#include <stdint.h>
#include <string.h>
 
#include "my_config.h"
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#include <sys/types.h>
 
#include "lex_string.h"
#include "my_inttypes.h"
#include "mysql_com.h"
#include "sql/table.h"        // GRANT_INFO
#include "sql/trigger_def.h"  // enum_trigger_event_type
 
class Query_tables_list;
class String;
class THD;
class sp_head;
struct MEM_ROOT;
 
using sql_mode_t = uint64_t;
 
/**
  This class represents a trigger object.
  Trigger can be created, initialized, parsed, and executed.
 
  Trigger attributes are usually stored on the memory root
  of the subject table TABLE object or its TABLE_SHARE
  (depending on whether it is something specific to the TABLE
  instance (e.g. sp_head), or static metadata that can be shared by
  all TABLE instances (e.g. subject table name).
 
  A Trigger object however can exist when the subject table does not.
  In this case, trigger attributes are stored on a separate memory root.
 
  @note We create separate sets of Trigger objects for TABLE_SHARE and
        TABLE instances. The set for the former is used to store static
        information about table's triggers and is directly associated
        with TABLE_SHARE object. The set for the latter is used primarily
        for trigger execution, and is asssociated with TABLE object with
        the help of Table_triggers_dispatcher class. Attributes representing
        static properties in Trigger instances of the latter type reference
        attributes/memory belonging to attributes of Trigger objects
        associated with the TABLE_SHARE.
 
  Trigger objects are created in two ways:
 
    1. loading from Data Dictionary (by Trigger_loader)
 
      In this case Trigger object is initialized from the data
      which is directly available in data dictionary;
 
      @see Trigger::create_from_dd().
 
    2. creating a new Trigger object that represents the trigger object being
       created by CREATE TRIGGER statement (by Table_trigger_dispatcher).
 
       In this case Trigger object is created temporarily.
 
      @see Trigger::create_from_parser().
*/
class Trigger {
 public:
  static Trigger *create_from_parser(THD *thd, TABLE *subject_table,
                                     String *binlog_create_trigger_stmt);
 
  static Trigger *create_from_dd(
      MEM_ROOT *mem_root, const LEX_CSTRING &trigger_name,
      const LEX_CSTRING &db_name, const LEX_CSTRING &subject_table_name,
      const LEX_CSTRING &definition, const LEX_CSTRING &definition_utf8,
      sql_mode_t sql_mode, const LEX_CSTRING &definer_user,
      const LEX_CSTRING &definer_host, const LEX_CSTRING &client_cs_name,
      const LEX_CSTRING &connection_cl_name, const LEX_CSTRING &db_cl_name,
      enum_trigger_event_type trg_event_type,
      enum_trigger_action_time_type trg_time_type, uint action_order,
      my_timeval created_timestamp);
 
  Trigger *clone_shallow(MEM_ROOT *mem_root) const;
 
  /**
    Constructs CREATE TRIGGER statement taking into account a value of
    the DEFINER clause.
 
    The point of this method is to create canonical forms of CREATE TRIGGER
    statement for writing into the binlog.
 
    @note
    A statement for the binlog form must preserve FOLLOWS/PRECEDES clause
    if it was in the original statement. The reason for that difference is this:
 
      - the Data Dictionary preserves the trigger execution order
    (action_order), thus FOLLOWS/PRECEDES clause is not needed.
 
      - moreover, FOLLOWS/PRECEDES clause usually makes problem in mysqldump,
        because CREATE TRIGGER statement will have a reference to
    not-yet-existing trigger (which is about to be created right after this
    one).
 
      - thus, FOLLOWS/PRECEDES must not be stored in the Data Dictionary.
 
      - on the other hand, the binlog contains statements in the user order (as
        the user executes them). Thus, it is important to preserve
        FOLLOWS/PRECEDES clause if the user has specified it so that the trigger
        execution order on master and slave will be the same.
 
    @param thd                thread context
    @param[out] binlog_query  well-formed CREATE TRIGGER statement for putting
                              into binlog (after successful execution)
    @param def_user           user part of a definer value
    @param def_host           host part of a definer value
 
    @return Operation status.
      @retval false Success
      @retval true  Failure
  */
  static bool construct_create_trigger_stmt_with_definer(
      THD *thd, String *binlog_query, const LEX_CSTRING &def_user,
      const LEX_CSTRING &def_host);
 
 public:
  bool execute(THD *thd);
 
  bool parse(THD *thd, bool is_upgrade);
 
  void add_tables_and_routines(THD *thd, Query_tables_list *prelocking_ctx,
                               Table_ref *table_list);
 
  void print_upgrade_warning(THD *thd);
 
 public:
  /************************************************************************
   * Attribute accessors.
   ***********************************************************************/
 
  const LEX_CSTRING &get_db_name() const { return m_db_name; }
 
  const LEX_CSTRING &get_subject_table_name() const {
    return m_subject_table_name;
  }
 
  const LEX_CSTRING &get_trigger_name() const { return m_trigger_name; }
 
  const LEX_CSTRING &get_definition() const { return m_definition; }
 
  const LEX_CSTRING &get_definition_utf8() const { return m_definition_utf8; }
 
  sql_mode_t get_sql_mode() const { return m_sql_mode; }
 
  const LEX_CSTRING &get_definer() const { return m_definer; }
 
  const LEX_CSTRING &get_definer_user() const { return m_definer_user; }
 
  const LEX_CSTRING &get_definer_host() const { return m_definer_host; }
 
  const LEX_CSTRING &get_client_cs_name() const { return m_client_cs_name; }
 
  const LEX_CSTRING &get_connection_cl_name() const {
    return m_connection_cl_name;
  }
 
  const LEX_CSTRING &get_db_cl_name() const { return m_db_cl_name; }
 
  enum_trigger_event_type get_event() const { return m_event; }
 
  const LEX_CSTRING &get_event_as_string() const;
 
  enum_trigger_action_time_type get_action_time() const {
    return m_action_time;
  }
 
  const LEX_CSTRING &get_action_time_as_string() const;
 
  bool is_created_timestamp_null() const {
    return m_created_timestamp.m_tv_sec == 0 &&
           m_created_timestamp.m_tv_usec == 0;
  }
 
  my_timeval get_created_timestamp() const { return m_created_timestamp; }
 
  ulonglong get_action_order() const { return m_action_order; }
 
  void set_action_order(ulonglong action_order) {
    m_action_order = action_order;
  }
 
  sp_head *get_sp() { return m_sp; }
 
  GRANT_INFO *get_subject_table_grant() { return &m_subject_table_grant; }
 
  bool has_parse_error() const { return m_parse_error_message; }
 
  const char *get_parse_error_message() const { return m_parse_error_message; }
 
  /**
    Construct a full CREATE TRIGGER statement from Trigger's data members.
 
    @param [in] thd                       Thread context
    @param [out] full_trigger_definition  Place where a CREATE TRIGGER
                                          statement be stored.
 
    @return Operation status
      @retval true   Failure
      @retval false  Success
  */
 
  bool create_full_trigger_definition(const THD *thd,
                                      String *full_trigger_definition) const;
 
 private:
  Trigger(const LEX_CSTRING &trigger_name, MEM_ROOT *mem_root,
          const LEX_CSTRING &db_name, const LEX_CSTRING &table_name,
          const LEX_CSTRING &definition, const LEX_CSTRING &definition_utf8,
          sql_mode_t sql_mode, const LEX_CSTRING &definer_user,
          const LEX_CSTRING &definer_host, const LEX_CSTRING &client_cs_name,
          const LEX_CSTRING &connection_cl_name, const LEX_CSTRING &db_cl_name,
          enum_trigger_event_type event_type,
          enum_trigger_action_time_type action_time, uint action_order,
          my_timeval created_timestamp);
 
 public:
  ~Trigger();
 
 private:
  void set_trigger_name(const LEX_CSTRING &trigger_name) {
    m_trigger_name = trigger_name;
  }
 
  void set_trigger_def(const LEX_CSTRING &trigger_def) {
    m_definition = trigger_def;
  }
 
  void set_trigger_def_utf8(const LEX_CSTRING &trigger_def_utf8) {
    m_definition_utf8 = trigger_def_utf8;
  }
 
  void set_parse_error_message(const char *error_message);
 
  /**
    Memory root to store all data of this Trigger object.
 
    This can be a pointer to the subject table share memory root (if this
    Trigger object is associated with TABLE_SHARE), table memory root
    (if this Trigger object is associated with TABLE object), or it can be a
    pointer to a dedicated memory root if subject table does not exist.
  */
  MEM_ROOT *m_mem_root;
 
  /**
    Full trigger definition reconstructed from a data loaded from the table
    mysql.trigger.
  */
  LEX_CSTRING m_full_trigger_definition;
 
 private:
  /************************************************************************
   * Mandatory trigger attributes loaded from data dictionary.
   * All these strings are allocated on TABLE_SHARE's memory root
   * (for both cases when Trigger object is bound to TABLE_SHARE object
   * and to TABLE object) or dedicated memory root pointed by m_mem_root.
   ***********************************************************************/
 
  /// Database name.
  LEX_CSTRING m_db_name;
 
  /// Table name.
  LEX_CSTRING m_subject_table_name;
 
  /// Trigger definition to save in DD.
  LEX_CSTRING m_definition;
 
  /// Trigger definition in UTF8 to save in DD.
  LEX_CSTRING m_definition_utf8;
 
  /// Trigger sql-mode.
  sql_mode_t m_sql_mode;
 
  /// Trigger definer.
  LEX_CSTRING m_definer;
 
  /// Trigger definer (user part).
  LEX_CSTRING m_definer_user;
 
  /// Trigger definer (host part).
  LEX_CSTRING m_definer_host;
 
  /// Character set context, used for parsing and executing trigger.
  LEX_CSTRING m_client_cs_name;
 
  /// Collation name of the connection within one a trigger are created.
  LEX_CSTRING m_connection_cl_name;
 
  /// Default database collation.
  LEX_CSTRING m_db_cl_name;
 
  /// Trigger event.
  enum_trigger_event_type m_event;
 
  /// Trigger action time.
  enum_trigger_action_time_type m_action_time;
 
  /**
    Current time when the trigger was created (measured in milliseconds since
    since 0 hours, 0 minutes, 0 seconds, January 1, 1970, UTC). This is the
    value of CREATED attribute.
 
    There is special value -- zero means CREATED is not set (NULL).
  */
  my_timeval m_created_timestamp;
 
  /**
    Action_order value for the trigger. Action_order is the ordinal position
    of the trigger in the list of triggers with the same EVENT_MANIPULATION,
    CONDITION_TIMING, and ACTION_ORIENTATION.
  */
  ulonglong m_action_order;
 
 private:
  /************************************************************************
   * All these strings are allocated on the TABLE_SHARE's mem-root.
   ***********************************************************************/
 
  /// Trigger name.
  LEX_CSTRING m_trigger_name;
 
 private:
  /************************************************************************
   * Other attributes. Allocated on m_mem_root if necessary.
   ***********************************************************************/
 
  /// Grant information for the trigger.
  GRANT_INFO m_subject_table_grant;
 
  /// Pointer to the sp_head corresponding to the trigger.
  sp_head *m_sp;
 
  /**
    Parse error message for trigger if it has one, nullptr otherwise.
 
    This error will be displayed when the user tries to manipulate or invoke
    triggers on a table that has broken triggers. It will get set only once
    per statement and thus will contain the first parse error encountered in
    the trigger file.
  */
  const char *m_parse_error_message;
};
 
///////////////////////////////////////////////////////////////////////////
 
#endif  // TRIGGER_H_INCLUDED