This the 4-th patch in scope of CS patch (BUG#11986).

The patch contains the following changes:
  - Introduce auxilary functions to convenient work with character sets:
    - resolve_charset();
    - resolve_collation();
    - get_default_db_collation();
  - Introduce lex_string_set();
  - Refactor Table_trigger_list::process_triggers() &
    sp_head::execute_trigger() to be consistent with other code;
  - Move reusable code from add_table_for_trigger() into
    build_trn_path(), check_trn_exists() and load_table_name_for_trigger()
    to be used in the following patch.
  - Rename triggers_file_ext and trigname_file_ext into TRN_EXT and
    TRG_EXT respectively.

include/my_sys.h

@@ -904,6 +904,14 @@ extern CHARSET_INFO *get_charset(uint cs_number, myf flags);
 extern CHARSET_INFO *get_charset_by_name(const char *cs_name, myf flags);
 extern CHARSET_INFO *get_charset_by_csname(const char *cs_name,
 					   uint cs_flags, myf my_flags);
+
+extern bool resolve_charset(CHARSET_INFO **cs,
+                            const char *cs_name,
+                            CHARSET_INFO *default_cs);
+extern bool resolve_collation(CHARSET_INFO **cl,
+                              const char *cl_name,
+                              CHARSET_INFO *default_cl);
+
 extern void free_charsets(void);
 extern char *get_charsets_dir(char *buf);
 extern my_bool my_charset_same(CHARSET_INFO *cs1, CHARSET_INFO *cs2);

mysys/charset.c

@@ -573,6 +573,70 @@ CHARSET_INFO *get_charset_by_csname(const char *cs_name,
 }
 
 
+/**
+  Resolve character set by the character set name (utf8, latin1, ...).
+
+  The function tries to resolve character set by the specified name. If
+  there is character set with the given name, it is assigned to the "cs"
+  parameter and FALSE is returned. If there is no such character set,
+  "default_cs" is assigned to the "cs" and TRUE is returned.
+
+  @param[out] cs        Variable to store character set.
+  @param[in] cs_name    Character set name.
+  @param[in] default_cs Default character set.
+
+  @return FALSE if character set was resolved successfully; TRUE if there
+  is no character set with given name.
+*/
+
+bool resolve_charset(CHARSET_INFO **cs,
+                     const char *cs_name,
+                     CHARSET_INFO *default_cs)
+{
+  *cs= get_charset_by_csname(cs_name, MY_CS_PRIMARY, MYF(0));
+
+  if (*cs == NULL)
+  {
+    *cs= default_cs;
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+
+/**
+  Resolve collation by the collation name (utf8_general_ci, ...).
+
+  The function tries to resolve collation by the specified name. If there
+  is collation with the given name, it is assigned to the "cl" parameter
+  and FALSE is returned. If there is no such collation, "default_cl" is
+  assigned to the "cl" and TRUE is returned.
+
+  @param[out] cl        Variable to store collation.
+  @param[in] cl_name    Collation name.
+  @param[in] default_cl Default collation.
+
+  @return FALSE if collation was resolved successfully; TRUE if there is no
+  collation with given name.
+*/
+
+bool resolve_collation(CHARSET_INFO **cl,
+                       const char *cl_name,
+                       CHARSET_INFO *default_cl)
+{
+  *cl= get_charset_by_name(cl_name, MYF(0));
+
+  if (*cl == NULL)
+  {
+    *cl= default_cl;
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+
 /*
   Escape string with backslashes (\)
 

sql/handler.cc

@@ -3376,8 +3376,8 @@ TYPELIB *ha_known_exts(void)
     const char **ext, *old_ext;
 
     known_extensions_id= mysys_usage_id;
-    found_exts.push_back((char*) triggers_file_ext);
-    found_exts.push_back((char*) trigname_file_ext);
+    found_exts.push_back((char*) TRG_EXT);
+    found_exts.push_back((char*) TRN_EXT);
 
     plugin_foreach(NULL, exts_handlerton,
                    MYSQL_STORAGE_ENGINE_PLUGIN, &found_exts);

sql/mysql_priv.h

@@ -101,7 +101,7 @@ char* query_table_status(THD *thd,const char *db,const char *table_name);
                         ER_WARN_DEPRECATED_SYNTAX, ER(ER_WARN_DEPRECATED_SYNTAX),    \
                         (Old), (Ver), (New));                                        \
     else                                                                             \
-      sql_print_warning("The syntax %s is deprecated and will be removed "           \
+      sql_print_warning("The syntax '%s' is deprecated and will be removed "         \
                         "in MySQL %s. Please use %s instead.", (Old), (Ver), (New)); \
   } while(0)
 
@@ -1590,6 +1590,7 @@ bool check_db_dir_existence(const char *db_name);
 bool load_db_opt(THD *thd, const char *path, HA_CREATE_INFO *create);
 bool load_db_opt_by_name(THD *thd, const char *db_name,
                          HA_CREATE_INFO *db_create_info);
+CHARSET_INFO *get_default_db_collation(THD *thd, const char *db_name);
 bool my_dbopt_init(void);
 void my_dbopt_cleanup(void);
 extern int creating_database; // How many database locks are made
@@ -1610,8 +1611,8 @@ extern const char *first_keyword, *my_localhost, *delayed_user, *binary_keyword;
 extern const char **errmesg;			/* Error messages */
 extern const char *myisam_recover_options_str;
 extern const char *in_left_expr_name, *in_additional_cond, *in_having_cond;
-extern const char * const triggers_file_ext;
-extern const char * const trigname_file_ext;
+extern const char * const TRG_EXT;
+extern const char * const TRN_EXT;
 extern Eq_creator eq_creator;
 extern Ne_creator ne_creator;
 extern Gt_creator gt_creator;
@@ -2146,6 +2147,12 @@ bool schema_table_store_record(THD *thd, TABLE *table);
 int item_create_init();
 void item_create_cleanup();
 
+inline void lex_string_set(LEX_STRING *lex_str, const char *c_str)
+{
+  lex_str->str= (char *) c_str;
+  lex_str->length= strlen(c_str);
+}
+
 #endif /* MYSQL_SERVER */
 #endif /* MYSQL_CLIENT */
 

sql/sp_head.cc

@@ -1268,30 +1268,31 @@ set_routine_security_ctx(THD *thd, sp_head *sp, bool is_proc,
 #endif // ! NO_EMBEDDED_ACCESS_CHECKS
 
 
-/*
+/**
+  Execute trigger stored program.
+
   Execute a trigger:
-   - changes security context for triggers
-   - switch to new memroot
-   - call sp_head::execute
-   - restore old memroot
-   - restores security context
+   - changes security context for triggers;
+   - switch to new memroot;
+   - call sp_head::execute;
+   - restore old memroot;
+   - restores security context.
 
-  SYNOPSIS
-    sp_head::execute_trigger()
-      thd               Thread handle
-      db                database name
-      table             table name
-      grant_info        GRANT_INFO structure to be filled with
-                        information about definer's privileges
-                        on subject table
+  @param thd        Thread context.
+  @param db_name    Database name.
+  @param table_name Table name.
+  @param grant_info GRANT_INFO structure to be filled with information
+                    about definer's privileges on subject table.
 
-  RETURN
-    FALSE  on success
-    TRUE   on error
+  @return Error status.
+    @retval FALSE on success.
+    @retval TRUE  on error.
 */
 
 bool
-sp_head::execute_trigger(THD *thd, const char *db, const char *table,
+sp_head::execute_trigger(THD *thd,
+                         const LEX_STRING *db_name,
+                         const LEX_STRING *table_name,
                          GRANT_INFO *grant_info)
 {
   sp_rcontext *octx = thd->spcont;
@@ -1304,6 +1305,46 @@ sp_head::execute_trigger(THD *thd, const char *db, const char *table,
   DBUG_ENTER("sp_head::execute_trigger");
   DBUG_PRINT("info", ("trigger %s", m_name.str));
 
+#ifndef NO_EMBEDDED_ACCESS_CHECKS
+  Security_context *save_ctx= NULL;
+
+
+  if (m_chistics->suid != SP_IS_NOT_SUID &&
+      m_security_ctx.change_security_context(thd,
+                                             &m_definer_user,
+                                             &m_definer_host,
+                                             &m_db,
+                                             &save_ctx))
+    DBUG_RETURN(TRUE);
+
+  /*
+    Fetch information about table-level privileges for subject table into
+    GRANT_INFO instance. The access check itself will happen in
+    Item_trigger_field, where this information will be used along with
+    information about column-level privileges.
+  */
+
+  fill_effective_table_privileges(thd,
+                                  grant_info,
+                                  db_name->str,
+                                  table_name->str);
+
+  /* Check that the definer has TRIGGER privilege on the subject table. */
+
+  if (!(grant_info->privilege & TRIGGER_ACL))
+  {
+    char priv_desc[128];
+    get_privilege_desc(priv_desc, sizeof(priv_desc), TRIGGER_ACL);
+
+    my_error(ER_TABLEACCESS_DENIED_ERROR, MYF(0), priv_desc,
+             thd->security_ctx->priv_user, thd->security_ctx->host_or_ip,
+             table_name->str);
+
+    m_security_ctx.restore_security_context(thd, save_ctx);
+    DBUG_RETURN(TRUE);
+  }
+#endif // NO_EMBEDDED_ACCESS_CHECKS
+
   /*
     Prepare arena and memroot for objects which lifetime is whole
     duration of trigger call (sp_rcontext, it's tables and items,
@@ -1336,6 +1377,11 @@ sp_head::execute_trigger(THD *thd, const char *db, const char *table,
 
 err_with_cleanup:
   thd->restore_active_arena(&call_arena, &backup_arena);
+
+#ifndef NO_EMBEDDED_ACCESS_CHECKS
+  m_security_ctx.restore_security_context(thd, save_ctx);
+#endif // NO_EMBEDDED_ACCESS_CHECKS
+
   delete nctx;
   call_arena.free_items();
   free_root(&call_mem_root, MYF(0));

sql/sp_head.h

@@ -216,8 +216,10 @@ public:
   destroy();
 
   bool
-  execute_trigger(THD *thd, const char *db, const char *table,
-                  GRANT_INFO *grant_onfo);
+  execute_trigger(THD *thd,
+                  const LEX_STRING *db_name,
+                  const LEX_STRING *table_name,
+                  GRANT_INFO *grant_info);
 
   bool
   execute_function(THD *thd, Item **args, uint argcount, Field *return_fld);

sql/sql_db.cc

@@ -538,6 +538,37 @@ bool load_db_opt_by_name(THD *thd, const char *db_name,
 }
 
 
+/**
+  Return default database collation.
+
+  @param thd     Thread context.
+  @param db_name Database name.
+
+  @return CHARSET_INFO object. The operation always return valid character
+    set, even if the database does not exist.
+*/
+
+CHARSET_INFO *get_default_db_collation(THD *thd, const char *db_name)
+{
+  HA_CREATE_INFO db_info;
+
+  if (thd->db != NULL && strcmp(db_name, thd->db) == 0)
+    return thd->db_charset;
+
+  load_db_opt_by_name(thd, db_name, &db_info);
+
+  /*
+    NOTE: even if load_db_opt_by_name() fails,
+    db_info.default_table_charset contains valid character set
+    (collation_server). We should not fail if load_db_opt_by_name() fails,
+    because it is valid case. If a database has been created just by
+    "mkdir", it does not contain db.opt file, but it is valid database.
+  */
+
+  return db_info.default_table_charset;
+}
+
+
 /*
   Create a database
 
@@ -751,10 +782,8 @@ bool mysql_alter_db(THD *thd, const char *db, HA_CREATE_INFO *create_info)
   if ((error=write_db_opt(thd, path, create_info)))
     goto exit;
 
-  /*
-     Change options if current database is being altered
-     TODO: Delete this code
-  */
+  /* Change options if current database is being altered. */
+
   if (thd->db && !strcmp(thd->db,db))
   {
     thd->db_charset= create_info->default_table_charset ?
@@ -1358,6 +1387,7 @@ bool mysql_change_db(THD *thd, const LEX_STRING *new_db_name, bool force_switch)
 
   Security_context *sctx= thd->security_ctx;
   ulong db_access= sctx->db_access;
+  CHARSET_INFO *db_default_cl;
 
   DBUG_ENTER("mysql_change_db");
   DBUG_PRINT("enter",("name: '%s'", new_db_name->str));
@@ -1487,16 +1517,9 @@ bool mysql_change_db(THD *thd, const LEX_STRING *new_db_name, bool force_switch)
     attributes and will be freed in THD::~THD().
   */
 
-  {
-    HA_CREATE_INFO db_options;
+  db_default_cl= get_default_db_collation(thd, new_db_file_name.str);
 
-    load_db_opt_by_name(thd, new_db_name->str, &db_options);
-
-    mysql_change_db_impl(thd, &new_db_file_name, db_access,
-                         db_options.default_table_charset ?
-                         db_options.default_table_charset :
-                         thd->variables.collation_server);
-  }
+  mysql_change_db_impl(thd, &new_db_file_name, db_access, db_default_cl);
 
   DBUG_RETURN(FALSE);
 }

sql/sql_trigger.cc

@@ -23,7 +23,7 @@
 static const LEX_STRING triggers_file_type=
   { C_STRING_WITH_LEN("TRIGGERS") };
 
-const char * const triggers_file_ext= ".TRG";
+const char * const TRG_EXT= ".TRG";
 
 /*
   Table of .TRG file field descriptors.
@@ -79,7 +79,7 @@ struct st_trigname
 static const LEX_STRING trigname_file_type=
   { C_STRING_WITH_LEN("TRIGGERNAME") };
 
-const char * const trigname_file_ext= ".TRN";
+const char * const TRN_EXT= ".TRN";
 
 static File_option trigname_file_parameters[]=
 {
@@ -132,6 +132,7 @@ private:
   LEX_STRING *trigger_table_value;
 };
 
+
 /*
   Create or drop trigger for table.
 
@@ -463,14 +464,14 @@ bool Table_triggers_list::create_trigger(THD *thd, TABLE_LIST *tables,
     sql_create_definition_file() files handles renaming and backup of older
     versions
   */
-  file.length= build_table_filename(file_buff, FN_REFLEN-1,
+  file.length= build_table_filename(file_buff, FN_REFLEN - 1,
                                     tables->db, tables->table_name,
-                                    triggers_file_ext, 0);
+                                    TRG_EXT, 0);
   file.str= file_buff;
   trigname_file.length= build_table_filename(trigname_buff, FN_REFLEN-1,
                                              tables->db,
                                              lex->spname->m_name.str,
-                                             trigname_file_ext, 0);
+                                             TRN_EXT, 0);
   trigname_file.str= trigname_buff;
 
   /* Use the filesystem to enforce trigger namespace constraints. */
@@ -604,7 +605,7 @@ err_with_cleanup:
 static bool rm_trigger_file(char *path, const char *db,
                             const char *table_name)
 {
-  build_table_filename(path, FN_REFLEN-1, db, table_name, triggers_file_ext, 0);
+  build_table_filename(path, FN_REFLEN-1, db, table_name, TRG_EXT, 0);
   return my_delete(path, MYF(MY_WME));
 }
 
@@ -627,8 +628,7 @@ static bool rm_trigger_file(char *path, const char *db,
 static bool rm_trigname_file(char *path, const char *db,
                              const char *trigger_name)
 {
-  build_table_filename(path, FN_REFLEN-1,
-                       db, trigger_name, trigname_file_ext, 0);
+  build_table_filename(path, FN_REFLEN - 1, db, trigger_name, TRN_EXT, 0);
   return my_delete(path, MYF(MY_WME));
 }
 
@@ -653,8 +653,8 @@ static bool save_trigger_file(Table_triggers_list *triggers, const char *db,
   char file_buff[FN_REFLEN];
   LEX_STRING file;
 
-  file.length= build_table_filename(file_buff, FN_REFLEN-1, db, table_name,
-                                    triggers_file_ext, 0);
+  file.length= build_table_filename(file_buff, FN_REFLEN - 1, db, table_name,
+                                    TRG_EXT, 0);
   file.str= file_buff;
   return sql_create_definition_file(NULL, &file, &triggers_file_type,
                                     (uchar*)triggers, triggers_file_parameters,
@@ -834,8 +834,8 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
 
   DBUG_ENTER("Table_triggers_list::check_n_load");
 
-  path.length= build_table_filename(path_buff, FN_REFLEN-1,
-                                    db, table_name, triggers_file_ext, 0);
+  path.length= build_table_filename(path_buff, FN_REFLEN - 1,
+                                    db, table_name, TRG_EXT, 0);
   path.str= path_buff;
 
   // QQ: should we analyze errno somehow ?
@@ -1106,7 +1106,7 @@ err_with_lex_cleanup:
       be merged into .FRM anyway.
     */
     my_error(ER_WRONG_OBJECT, MYF(0),
-             table_name, triggers_file_ext+1, "TRIGGER");
+             table_name, TRG_EXT + 1, "TRIGGER");
     DBUG_RETURN(1);
   }
 
@@ -1166,43 +1166,38 @@ bool Table_triggers_list::get_trigger_info(THD *thd, trg_event_type event,
 }
 
 
-/*
+/**
   Find trigger's table from trigger identifier and add it to
   the statement table list.
 
-  SYNOPSIS
-    mysql_table_for_trigger()
-      thd    - current thread context
-      trig   - identifier for trigger
-      if_exists - treat a not existing trigger as a warning if TRUE
-      table - pointer to TABLE_LIST object for the table trigger (output)
-
-  RETURN VALUE
-    0 Success
-    1 Error
+  @param[in] thd       Thread context.
+  @param[in] trg_name  Trigger name.
+  @param[in] if_exists TRUE if SQL statement contains "IF EXISTS" clause.
+                       That means a warning instead of error should be
+                       thrown if trigger with given name does not exist.
+  @param[out] table    Pointer to TABLE_LIST object for the
+                       table trigger.
+
+  @return Operation status
+    @retval FALSE On success.
+    @retval TRUE  Otherwise.
 */
 
-int
-add_table_for_trigger(THD *thd, sp_name *trig, bool if_exists,
+bool add_table_for_trigger(THD *thd,
+                           sp_name *trg_name,
+                           bool if_exists,
                            TABLE_LIST **table)
 {
   LEX *lex= thd->lex;
-  char path_buff[FN_REFLEN];
-  LEX_STRING path;
-  File_parser *parser;
-  struct st_trigname trigname;
-  Handle_old_incorrect_trigger_table_hook trigger_table_hook(
-                                          path_buff, &trigname.trigger_table);
+  char trn_path_buff[FN_REFLEN];
+  LEX_STRING trn_path= { trn_path_buff, 0 };
+  LEX_STRING tbl_name;
 
   DBUG_ENTER("add_table_for_trigger");
-  DBUG_ASSERT(table != NULL);
 
-  path.length= build_table_filename(path_buff, FN_REFLEN-1,
-                                    trig->m_db.str, trig->m_name.str,
-                                    trigname_file_ext, 0);
-  path.str= path_buff;
+  build_trn_path(thd, trg_name, &trn_path);
 
-  if (access(path_buff, F_OK))
+  if (check_trn_exists(&trn_path))
   {
     if (if_exists)
     {
@@ -1210,39 +1205,27 @@ add_table_for_trigger(THD *thd, sp_name *trig, bool if_exists,
                           MYSQL_ERROR::WARN_LEVEL_NOTE,
                           ER_TRG_DOES_NOT_EXIST,
                           ER(ER_TRG_DOES_NOT_EXIST));
+
       *table= NULL;
-      DBUG_RETURN(0);
-    }
 
-    my_error(ER_TRG_DOES_NOT_EXIST, MYF(0));
-    DBUG_RETURN(1);
+      DBUG_RETURN(FALSE);
     }
 
-  if (!(parser= sql_parse_prepare(&path, thd->mem_root, 1)))
-    DBUG_RETURN(1);
-
-  if (!is_equal(&trigname_file_type, parser->type()))
-  {
-    my_error(ER_WRONG_OBJECT, MYF(0), trig->m_name.str, trigname_file_ext+1,
-             "TRIGGERNAME");
-    DBUG_RETURN(1);
+    my_error(ER_TRG_DOES_NOT_EXIST, MYF(0));
+    DBUG_RETURN(TRUE);
   }
 
-  if (parser->parse((uchar*)&trigname, thd->mem_root,
-                    trigname_file_parameters, 1,
-                    &trigger_table_hook))
-    DBUG_RETURN(1);
+  if (load_table_name_for_trigger(thd, trg_name, &trn_path, &tbl_name))
+    DBUG_RETURN(TRUE);
 
   /* We need to reset statement table list to be PS/SP friendly. */
   lex->query_tables= 0;
   lex->query_tables_last= &lex->query_tables;
-  *table= sp_add_to_query_tables(thd, lex, trig->m_db.str,
-                                 trigname.trigger_table.str, TL_IGNORE);
 
-  if (! *table)
-    DBUG_RETURN(1);
+  *table= sp_add_to_query_tables(thd, lex, trg_name->m_db.str,
+                                 tbl_name.str, TL_IGNORE);
 
-  DBUG_RETURN(0);
+  DBUG_RETURN(*table ? FALSE : TRUE);
 }
 
 
@@ -1426,7 +1409,7 @@ Table_triggers_list::change_table_name_in_trignames(const char *db_name,
   {
     trigname_file.length= build_table_filename(trigname_buff, FN_REFLEN-1,
                                                db_name, trigger->str,
-                                               trigname_file_ext, 0);
+                                               TRN_EXT, 0);
     trigname_file.str= trigname_buff;
 
     trigname.trigger_table= *new_table_name;
@@ -1535,17 +1518,33 @@ end:
 }
 
 
-bool Table_triggers_list::process_triggers(THD *thd, trg_event_type event,
+/**
+  Execute trigger for given (event, time) pair.
+
+  The operation executes trigger for the specified event (insert, update,
+  delete) and time (after, before) if it is set.
+
+  @param thd
+  @param event
+  @param time_type,
+  @param old_row_is_record1
+
+  @return Error status.
+    @retval FALSE on success.
+    @retval TRUE  on error.
+*/
+
+bool Table_triggers_list::process_triggers(THD *thd,
+                                           trg_event_type event,
                                            trg_action_time_type time_type,
                                            bool old_row_is_record1)
 {
-  bool err_status= FALSE;
-  sp_head *sp_trigger= bodies[event][time_type];
-
-  if (sp_trigger)
-  {
+  bool err_status;
   Sub_statement_state statement_state;
 
+  if (!bodies[event][time_type])
+    return FALSE;
+
   if (old_row_is_record1)
   {
     old_field= record1_field;
@@ -1556,56 +1555,17 @@ bool Table_triggers_list::process_triggers(THD *thd, trg_event_type event,
     new_field= record1_field;
     old_field= trigger_table->field;
   }
-#ifndef NO_EMBEDDED_ACCESS_CHECKS
-    Security_context *sctx= &sp_trigger->m_security_ctx;
-    Security_context *save_ctx= NULL;
-
-
-    if (sp_trigger->m_chistics->suid != SP_IS_NOT_SUID &&
-        sctx->change_security_context(thd,
-                                      &sp_trigger->m_definer_user,
-                                      &sp_trigger->m_definer_host,
-                                      &sp_trigger->m_db,
-                                      &save_ctx))
-      return TRUE;
-
-    /*
-      Fetch information about table-level privileges to GRANT_INFO structure for
-      subject table. Check of privileges that will use it and information about
-      column-level privileges will happen in Item_trigger_field::fix_fields().
-    */
-
-    fill_effective_table_privileges(thd,
-                                    &subject_table_grants[event][time_type],
-                                    trigger_table->s->db.str,
-                                    trigger_table->s->table_name.str);
-
-    /* Check that the definer has TRIGGER privilege on the subject table. */
-
-    if (!(subject_table_grants[event][time_type].privilege & TRIGGER_ACL))
-    {
-      char priv_desc[128];
-      get_privilege_desc(priv_desc, sizeof(priv_desc), TRIGGER_ACL);
-
-      my_error(ER_TABLEACCESS_DENIED_ERROR, MYF(0), priv_desc,
-               thd->security_ctx->priv_user, thd->security_ctx->host_or_ip,
-               trigger_table->s->table_name.str);
-
-      sctx->restore_security_context(thd, save_ctx);
-      return TRUE;
-    }
-#endif // NO_EMBEDDED_ACCESS_CHECKS
 
   thd->reset_sub_statement_state(&statement_state, SUB_STMT_TRIGGER);
-    err_status= sp_trigger->execute_trigger
-      (thd, trigger_table->s->db.str, trigger_table->s->table_name.str,
+
+  err_status=
+    bodies[event][time_type]->execute_trigger(
+      thd,
+      &trigger_table->s->db,
+      &trigger_table->s->table_name,
       &subject_table_grants[event][time_type]);
-    thd->restore_sub_statement_state(&statement_state);
 
-#ifndef NO_EMBEDDED_ACCESS_CHECKS
-    sctx->restore_security_context(thd, save_ctx);
-#endif // NO_EMBEDDED_ACCESS_CHECKS
-  }
+  thd->restore_sub_statement_state(&statement_state);
 
   return err_status;
 }
@@ -1747,3 +1707,95 @@ process_unknown_string(char *&unknown_key, uchar* base, MEM_ROOT *mem_root,
   }
   DBUG_RETURN(FALSE);
 }
+
+
+/**
+  Contruct path to TRN-file.
+
+  @param thd[in]        Thread context.
+  @param trg_name[in]   Trigger name.
+  @param trn_path[out]  Variable to store constructed path
+*/
+
+void build_trn_path(THD *thd, const sp_name *trg_name, LEX_STRING *trn_path)
+{
+  /* Construct path to the TRN-file. */
+
+  trn_path->length= build_table_filename(trn_path->str,
+                                         FN_REFLEN - 1,
+                                         trg_name->m_db.str,
+                                         trg_name->m_name.str,
+                                         TRN_EXT,
+                                         0);
+}
+
+
+/**
+  Check if TRN-file exists.
+
+  @return
+    @retval TRUE  if TRN-file does not exist.
+    @retval FALSE if TRN-file exists.
+*/
+
+bool check_trn_exists(const LEX_STRING *trn_path)
+{
+  return access(trn_path->str, F_OK) != 0;
+}
+
+
+/**
+  Retrieve table name for given trigger.
+
+  @param thd[in]        Thread context.
+  @param trg_name[in]   Trigger name.
+  @param trn_path[in]   Path to the corresponding TRN-file.
+  @param tbl_name[out]  Variable to store retrieved table name.
+
+  @return Error status.
+    @retval FALSE on success.
+    @retval TRUE  if table name could not be retrieved.
+*/
+
+bool load_table_name_for_trigger(THD *thd,
+                                 const sp_name *trg_name,
+                                 const LEX_STRING *trn_path,
+                                 LEX_STRING *tbl_name)
+{
+  File_parser *parser;
+  struct st_trigname trn_data;
+
+  Handle_old_incorrect_trigger_table_hook trigger_table_hook(
+                                          trn_path->str,
+                                          &trn_data.trigger_table);
+
+  DBUG_ENTER("load_table_name_for_trigger");
+
+  /* Parse the TRN-file. */
+
+  if (!(parser= sql_parse_prepare(trn_path, thd->mem_root, TRUE)))
+    DBUG_RETURN(TRUE);
+
+  if (!is_equal(&trigname_file_type, parser->type()))
+  {
+    my_error(ER_WRONG_OBJECT, MYF(0),
+             trg_name->m_name.str,
+             TRN_EXT + 1,
+             "TRIGGERNAME");
+
+    DBUG_RETURN(TRUE);
+  }
+
+  if (parser->parse((uchar*) &trn_data, thd->mem_root,
+                    trigname_file_parameters, 1,
+                    &trigger_table_hook))
+    DBUG_RETURN(TRUE);
+
+  /* Copy trigger table name. */
+
+  *tbl_name= trn_data.trigger_table;
+
+  /* That's all. */
+
+  DBUG_RETURN(FALSE);
+}

sql/sql_trigger.h

@@ -17,7 +17,7 @@
 /*
   This class holds all information about triggers of table.
 
-  QQ: Will it be merged into TABLE in future ?
+  QQ: Will it be merged into TABLE in the future ?
 */
 
 class Table_triggers_list: public Sql_alloc
@@ -143,6 +143,17 @@ private:
 extern const LEX_STRING trg_action_time_type_names[];
 extern const LEX_STRING trg_event_type_names[];
 
-int
-add_table_for_trigger(THD *thd, sp_name *trig, bool if_exists,
+bool add_table_for_trigger(THD *thd,
+                           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_STRING *trn_path);
+
+bool load_table_name_for_trigger(THD *thd,
+                                 const sp_name *trg_name,
+                                 const LEX_STRING *trn_path,
+                                 LEX_STRING *tbl_name);
+