mariadb/sql/sql_trigger.h

#ifndef SQL_TRIGGER_INCLUDED
#define SQL_TRIGGER_INCLUDED

/*
   Copyright (c) 2004, 2011, Oracle and/or its affiliates.
   Copyright (c) 2017, MariaDB Corporation.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA */

#include <mysqld_error.h>

/* Forward declarations */

class Item_trigger_field;
class sp_head;
class sp_name;
class Query_tables_list;
struct TABLE_LIST;
class Query_tables_list;

/** Event on which trigger is invoked. */
enum trg_event_type
{
  TRG_EVENT_INSERT= 0,
  TRG_EVENT_UPDATE= 1,
  TRG_EVENT_DELETE= 2,
  TRG_EVENT_MAX
};

static inline uint8 trg2bit(enum trg_event_type trg)
{ return static_cast<uint8>(1 << static_cast<int>(trg)); }

#include "table.h"                              /* GRANT_INFO */

/*
  We need this two enums here instead of sql_lex.h because
  at least one of them is used by Item_trigger_field interface.

  Time when trigger is invoked (i.e. before or after row actually
  inserted/updated/deleted).
*/
enum trg_action_time_type
{
  TRG_ACTION_BEFORE= 0, TRG_ACTION_AFTER= 1, TRG_ACTION_MAX
};

enum trigger_order_type
{
  TRG_ORDER_NONE= 0,
  TRG_ORDER_FOLLOWS= 1,
  TRG_ORDER_PRECEDES= 2
};


struct st_trg_execution_order
{
  /**
    FOLLOWS or PRECEDES as specified in the CREATE TRIGGER statement.
  */
  enum trigger_order_type ordering_clause;

  /**
    Trigger name referenced in the FOLLOWS/PRECEDES clause of the
    CREATE TRIGGER statement.
  */
  LEX_CSTRING anchor_trigger_name;
};


class Table_triggers_list;

/**
   The trigger object
*/

class Trigger :public Sql_alloc
{
public:
    Trigger(Table_triggers_list *base_arg, sp_head *code):
    base(base_arg), body(code), next(0), trigger_fields(0), action_order(0)
  {
    bzero((char *)&subject_table_grants, sizeof(subject_table_grants));
  }
  ~Trigger();
  Table_triggers_list *base;
  sp_head *body;
  Trigger *next;                                /* Next trigger of same type */

  /**
    Heads of the lists linking items for all fields used in triggers
    grouped by event and action_time.
  */
  Item_trigger_field *trigger_fields;
  LEX_CSTRING name;
  LEX_CSTRING on_table_name;                     /* Raw table name */
  LEX_CSTRING definition;
  LEX_CSTRING definer;

  /* Character sets used */
  LEX_CSTRING client_cs_name;
  LEX_CSTRING connection_cl_name;
  LEX_CSTRING db_cl_name;

  GRANT_INFO subject_table_grants;
  sql_mode_t sql_mode;
  /* Store create time. Can't be mysql_time_t as this holds also sub seconds */
  ulonglong create_time;
  trg_event_type event;
  trg_action_time_type action_time;
  uint action_order;

  bool is_fields_updated_in_trigger(MY_BITMAP *used_fields);
  void get_trigger_info(LEX_CSTRING *stmt, LEX_CSTRING *body,
                        LEX_STRING *definer);
  /* Functions executed over each active trigger */
  bool change_on_table_name(void* param_arg);
  bool change_table_name(void* param_arg);
  bool add_to_file_list(void* param_arg);
};

typedef bool (Trigger::*Triggers_processor)(void *arg);

/**
  This class holds all information about triggers of table.
*/

class Table_triggers_list: public Sql_alloc
{
  friend class Trigger;

  /* Points to first trigger for a certain type */
  Trigger *triggers[TRG_EVENT_MAX][TRG_ACTION_MAX];
  /**
    Copy of TABLE::Field array which all fields made nullable
    (using extra_null_bitmap, if needed). Used for NEW values in
    BEFORE INSERT/UPDATE triggers.
  */
  Field             **record0_field;
  uchar              *extra_null_bitmap;
  /**
    Copy of TABLE::Field array with field pointers set to TABLE::record[1]
    buffer instead of TABLE::record[0] (used for OLD values in on UPDATE
    trigger and DELETE trigger when it is called for REPLACE).
  */
  Field             **record1_field;
  /**
    During execution of trigger new_field and old_field should point to the
    array of fields representing new or old version of row correspondingly
    (so it can point to TABLE::field or to Tale_triggers_list::record1_field)
  */
  Field             **new_field;
  Field             **old_field;

  /* TABLE instance for which this triggers list object was created */
  TABLE *trigger_table;

  /**
     This flag indicates that one of the triggers was not parsed successfully,
     and as a precaution the object has entered a state where all trigger
     access results in errors until all such triggers are dropped. It is not
     safe to add triggers since we don't know if the broken trigger has the
     same name or event type. Nor is it safe to invoke any trigger for the
     aforementioned reasons. The only safe operations are drop_trigger and
     drop_all_triggers.

     @see Table_triggers_list::set_parse_error
   */
  bool m_has_unparseable_trigger;

  /**
    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.
   */
  char m_parse_error_message[MYSQL_ERRMSG_SIZE];
  uint count;                                   /* Number of triggers */

public:
  /**
    Field responsible for storing triggers definitions in file.
    It have to be public because we are using it directly from parser.
  */
  List<LEX_CSTRING>  definitions_list;
  /**
    List of sql modes for triggers
  */
  List<ulonglong> definition_modes_list;
  /** Create times for triggers */
  List<ulonglong> create_times;

  List<LEX_CSTRING>  definers_list;

  /* Character set context, used for parsing and executing triggers. */

  List<LEX_CSTRING> client_cs_names;
  List<LEX_CSTRING> connection_cl_names;
  List<LEX_CSTRING> db_cl_names;

  /* End of character ser context. */

  Table_triggers_list(TABLE *table_arg)
    :record0_field(0), extra_null_bitmap(0), record1_field(0),
    trigger_table(table_arg),
    m_has_unparseable_trigger(false), count(0)
  {
    bzero((char *) triggers, sizeof(triggers));
  }
  ~Table_triggers_list();

  bool create_trigger(THD *thd, TABLE_LIST *table, String *stmt_query);
  bool drop_trigger(THD *thd, TABLE_LIST *table, String *stmt_query);
  bool process_triggers(THD *thd, trg_event_type event,
                        trg_action_time_type time_type,
                        bool old_row_is_record1);
  void empty_lists();
  bool create_lists_needed_for_files(MEM_ROOT *root);
  bool save_trigger_file(THD *thd, const LEX_CSTRING *db, const LEX_CSTRING *table_name);

  static bool check_n_load(THD *thd, const LEX_CSTRING *db, const LEX_CSTRING *table_name,
                           TABLE *table, bool names_only);
  static bool drop_all_triggers(THD *thd, const LEX_CSTRING *db,
                                const LEX_CSTRING *table_name, myf MyFlags);
  static bool change_table_name(THD *thd, const LEX_CSTRING *db,
                                const LEX_CSTRING *old_alias,
                                const LEX_CSTRING *old_table,
                                const LEX_CSTRING *new_db,
                                const LEX_CSTRING *new_table);
  void add_trigger(trg_event_type event_type, 
                   trg_action_time_type action_time,
                   trigger_order_type ordering_clause,
                   LEX_CSTRING *anchor_trigger_name,
                   Trigger *trigger);
  Trigger *get_trigger(trg_event_type event_type, 
                       trg_action_time_type action_time)
  {
    return triggers[event_type][action_time];
  }
  /* Simpler version of the above, to avoid casts in the code */
  Trigger *get_trigger(uint event_type, uint action_time)
  {
    return get_trigger((trg_event_type) event_type,
                       (trg_action_time_type) action_time);
  }

  bool has_triggers(trg_event_type event_type, 
                    trg_action_time_type action_time)
  {
    return get_trigger(event_type,action_time) != 0;
  }
  bool has_delete_triggers()
  {
    return (has_triggers(TRG_EVENT_DELETE,TRG_ACTION_BEFORE) ||
            has_triggers(TRG_EVENT_DELETE,TRG_ACTION_AFTER));
  }

  void mark_fields_used(trg_event_type event);

  void set_parse_error_message(char *error_message);

  friend class Item_trigger_field;

  bool add_tables_and_routines_for_triggers(THD *thd,
                                            Query_tables_list *prelocking_ctx,
                                            TABLE_LIST *table_list);

  Field **nullable_fields() { return record0_field; }
  void reset_extra_null_bitmap()
  {
    size_t null_bytes= (trigger_table->s->fields -
                        trigger_table->s->null_fields + 7)/8;
    bzero(extra_null_bitmap, null_bytes);
  }

  Trigger *find_trigger(const LEX_CSTRING *name, bool remove_from_list);

  Trigger* for_all_triggers(Triggers_processor func, void *arg);

private:
  bool prepare_record_accessors(TABLE *table);
  Trigger *change_table_name_in_trignames(const LEX_CSTRING *old_db_name,
                                          const LEX_CSTRING *new_db_name,
                                          const LEX_CSTRING *new_table_name,
                                          Trigger *trigger);
  bool change_table_name_in_triggers(THD *thd,
                                     const LEX_CSTRING *old_db_name,
                                     const LEX_CSTRING *new_db_name,
                                     const LEX_CSTRING *old_table_name,
                                     const LEX_CSTRING *new_table_name);

  bool check_for_broken_triggers() 
  {
    if (m_has_unparseable_trigger)
    {
      my_message(ER_PARSE_ERROR, m_parse_error_message, MYF(0));
      return true;
    }
    return false;
  }
};

bool add_table_for_trigger(THD *thd,
                           const sp_name *trg_name,
                           bool continue_if_not_exist,
                           TABLE_LIST **table);

void build_trn_path(THD *thd, const sp_name *trg_name, LEX_STRING *trn_path);

bool check_trn_exists(const LEX_CSTRING *trn_path);

bool load_table_name_for_trigger(THD *thd,
                                 const sp_name *trg_name,
                                 const LEX_CSTRING *trn_path,
                                 LEX_CSTRING *tbl_name);
bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create);

extern const char * const TRG_EXT;
extern const char * const TRN_EXT;

#endif /* SQL_TRIGGER_INCLUDED */