sql_trigger.cc 12.5 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434
#include "mysql_priv.h"
#include "sp_head.h"
#include "sql_trigger.h"
#include "parse_file.h"


static const LEX_STRING triggers_file_type= {(char *)"TRIGGERS", 8};
static const char * const triggers_file_ext= ".TRG";

/*
  Table of .TRG file field descriptors.
  We have here only one field now because in nearest future .TRG
  files will be merged into .FRM files (so we don't need something
  like md5 or created fields).
*/
static File_option triggers_file_parameters[]=
{
  {{(char*)"triggers", 8}, offsetof(Table_triggers_list, definitions_list),
   FILE_OPTIONS_STRLIST},
  {{NULL, 0}, 0, FILE_OPTIONS_STRING}
};


/*
  Create or drop trigger for table.

  SYNOPSIS
    mysql_create_or_drop_trigger()
      thd    - current thread context (including trigger definition in LEX)
      tables - table list containing one table for which trigger is created.
      create - whenever we create (true) or drop (false) trigger

  NOTE
    This function is mainly responsible for opening and locking of table and
    invalidation of all its instances in table cache after trigger creation.
    Real work on trigger creation/dropping is done inside Table_triggers_list
    methods.

  RETURN VALUE
    0 - Success, non-0 in case of error.
*/
int mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
{
  TABLE *table;
  int result= 0;

  DBUG_ENTER("mysql_create_or_drop_trigger");

  /*
    QQ: This function could be merged in mysql_alter_table() function
    But do we want this ?
  */

  if (open_and_lock_tables(thd, tables))
    DBUG_RETURN(-1);

  // TODO: We should check if user has TRIGGER privilege for table here.

  table= tables->table;

  /*
    We do not allow creation of triggers on views or temporary tables.
    We have to do this check here and not in
    Table_triggers_list::create_trigger() because we want to avoid messing
    with table cash for views and temporary tables.
  */
  if (tables->view || table->tmp_table != NO_TMP_TABLE)
  {
    my_error(ER_TRG_ON_VIEW_OR_TEMP_TABLE, MYF(0), tables->alias);
    DBUG_RETURN(-1);
  }

  if (!table->triggers)
  {
    if (!create)
    {
      my_error(ER_TRG_DOES_NOT_EXIST, MYF(0));
      DBUG_RETURN(-1);
    }

    if (!(table->triggers= new (&table->mem_root) Table_triggers_list()))
      DBUG_RETURN(-1);
  }

  /*
    We don't want perform our operations while global read lock is held
    so we have to wait until its end and then prevent it from occuring
    again until we are done. (Acquiring LOCK_open is not enough because
    global read lock is held without helding LOCK_open).
  */
  if (wait_if_global_read_lock(thd, 0))
    DBUG_RETURN(-1);

  VOID(pthread_mutex_lock(&LOCK_open));
  if ((create ? table->triggers->create_trigger(thd, tables):
                table->triggers->drop_trigger(thd, tables)))
    result= -1;

  /* It is sensible to invalidate table in any case */
  close_cached_table(thd, table);
  VOID(pthread_mutex_unlock(&LOCK_open));
  start_waiting_global_read_lock(thd);

  if (!result)
    send_ok(thd);

  DBUG_RETURN(result);
}


/*
  Create trigger for table.

  SYNOPSIS
    create_trigger()
      thd    - current thread context (including trigger definition in LEX)
      tables - table list containing one open table for which trigger is
               created.

  RETURN VALUE
    False - success
    True  - error
*/
bool Table_triggers_list::create_trigger(THD *thd, TABLE_LIST *tables)
{
  LEX *lex= thd->lex;
  TABLE *table= tables->table;
  char dir_buff[FN_REFLEN], file_buff[FN_REFLEN];
  LEX_STRING dir, file;
  MEM_ROOT *old_global_root;
  LEX_STRING *trg_def, *name;
  List_iterator_fast<LEX_STRING> it(names_list);

  /* We don't allow creation of several triggers of the same type yet */
  if (bodies[lex->trg_chistics.event][lex->trg_chistics.action_time])
  {
    my_error(ER_TRG_ALREADY_EXISTS, MYF(0));
    return 1;
  }

  /* Let us check if trigger with the same name exists */
  while ((name= it++))
  {
    if (my_strcasecmp(system_charset_info, lex->name_and_length.str,
                      name->str) == 0)
    {
      my_error(ER_TRG_ALREADY_EXISTS, MYF(0));
      return 1;
    }
  }

  /*
    Here we are creating file with triggers and save all triggers in it.
    sql_create_definition_file() files handles renaming and backup of older
    versions
  */
  strxnmov(dir_buff, FN_REFLEN, mysql_data_home, "/", tables->db, "/", NullS);
  dir.length= unpack_filename(dir_buff, dir_buff);
  dir.str= dir_buff;
  file.length=  strxnmov(file_buff, FN_REFLEN, tables->real_name,
                         triggers_file_ext, NullS) - file_buff;
  file.str= file_buff;

  old_global_root= my_pthread_getspecific_ptr(MEM_ROOT*, THR_MALLOC);
  my_pthread_setspecific_ptr(THR_MALLOC, &table->mem_root);

  /*
    Soon we will invalidate table object and thus Table_triggers_list object
    so don't care about place to which trg_def->ptr points and other
    invariants (e.g. we don't bother to update names_list)

    QQ: Hmm... probably we should not care about setting up active thread
        mem_root too.
  */
  if (!(trg_def= (LEX_STRING *)alloc_root(&table->mem_root,
                                          sizeof(LEX_STRING))) ||
      definitions_list.push_back(trg_def))
  {
    my_pthread_setspecific_ptr(THR_MALLOC, old_global_root);
    return 1;
  }

  trg_def->str= thd->query;
  trg_def->length= thd->query_length;

  my_pthread_setspecific_ptr(THR_MALLOC, old_global_root);

  return sql_create_definition_file(&dir, &file, &triggers_file_type,
                                    (gptr)this, triggers_file_parameters, 3);
}


/*
  Drop trigger for table.

  SYNOPSIS
    drop_trigger()
      thd    - current thread context (including trigger definition in LEX)
      tables - table list containing one open table for which trigger is
               dropped.

  RETURN VALUE
    False - success
    True  - error
*/
bool Table_triggers_list::drop_trigger(THD *thd, TABLE_LIST *tables)
{
  LEX *lex= thd->lex;
  LEX_STRING *name;
  List_iterator_fast<LEX_STRING> it_name(names_list);
  List_iterator<LEX_STRING>      it_def(definitions_list);

  while ((name= it_name++))
  {
    it_def++;

    if (my_strcasecmp(system_charset_info, lex->name_and_length.str,
                      name->str) == 0)
    {
      /*
        Again we don't care much about other things required for
        clean trigger removing since table will be reopened anyway.
      */
      it_def.remove();

      if (definitions_list.is_empty())
      {
        char path[FN_REFLEN];

        /*
          TODO: Probably instead of removing .TRG file we should move
          to archive directory but this should be done as part of
          parse_file.cc functionality (because we will need it
          elsewhere).
        */
        strxnmov(path, FN_REFLEN, mysql_data_home, "/", tables->db, "/",
                 tables->real_name, triggers_file_ext, NullS);
        unpack_filename(path, path);
        return my_delete(path, MYF(MY_WME));
      }
      else
      {
        char dir_buff[FN_REFLEN], file_buff[FN_REFLEN];
        LEX_STRING dir, file;

        strxnmov(dir_buff, FN_REFLEN, mysql_data_home, "/", tables->db,
                 "/", NullS);
        dir.length= unpack_filename(dir_buff, dir_buff);
        dir.str= dir_buff;
        file.length=  strxnmov(file_buff, FN_REFLEN, tables->real_name,
                               triggers_file_ext, NullS) - file_buff;
        file.str= file_buff;

        return sql_create_definition_file(&dir, &file, &triggers_file_type,
                                          (gptr)this,
                                          triggers_file_parameters, 3);
      }
    }
  }

  my_error(ER_TRG_DOES_NOT_EXIST, MYF(0));
  return 1;
}


Table_triggers_list::~Table_triggers_list()
{
  for (int i= 0; i < 3; i++)
    for (int j= 0; j < 2; j++)
      delete bodies[i][j];

  if (old_field)
    for (Field **fld_ptr= old_field; *fld_ptr; fld_ptr++)
      delete *fld_ptr;
}


/*
  Check whenever .TRG file for table exist and load all triggers it contains.

  SYNOPSIS
    check_n_load()
      thd        - current thread context
      db         - table's database name
      table_name - table's name
      table      - pointer to table object

  RETURN VALUE
    False - success
    True  - error
*/
bool Table_triggers_list::check_n_load(THD *thd, const char *db,
                                       const char *table_name, TABLE *table)
{
  char path_buff[FN_REFLEN];
  LEX_STRING path;
  File_parser *parser;
  MEM_ROOT *old_global_mem_root;

  DBUG_ENTER("Table_triggers_list::check_n_load");

  strxnmov(path_buff, FN_REFLEN, mysql_data_home, "/", db, "/", table_name,
           triggers_file_ext, NullS);
  path.length= unpack_filename(path_buff, path_buff);
  path.str= path_buff;

  // QQ: should we analyze errno somehow ?
  if (access(path_buff, F_OK))
    DBUG_RETURN(0);

  /*
    File exists so we got to load triggers
    FIXME: A lot of things to do here e.g. how about other funcs and being
    more paranoical ?
  */

  if ((parser= sql_parse_prepare(&path, &table->mem_root, 1)))
  {
    if (!strncmp(triggers_file_type.str, parser->type()->str,
                 parser->type()->length))
    {
      int i;
      Table_triggers_list *triggers_info=
        new (&table->mem_root) Table_triggers_list();

      if (!triggers_info)
        DBUG_RETURN(1);

      if (parser->parse((gptr)triggers_info, &table->mem_root,
                        triggers_file_parameters, 1))
        DBUG_RETURN(1);

      table->triggers= triggers_info;

      /*
        We have to prepare array of Field objects which will represent OLD.*
        row values by referencing to record[1] instead of record[0]

        TODO: This could be avoided if there is no ON UPDATE trigger.
      */
      if (!(triggers_info->old_field=
              (Field **)alloc_root(&table->mem_root, (table->fields + 1) *
                                                     sizeof(Field*))))
        DBUG_RETURN(1);

      for (i= 0; i < table->fields; i++)
      {
        /*
          QQ: it is supposed that it is ok to use this function for field
              cloning...
        */
        if (!(triggers_info->old_field[i]=
                table->field[i]->new_field(&table->mem_root, table)))
          DBUG_RETURN(1);
        triggers_info->old_field[i]->move_field((my_ptrdiff_t)
                                                (table->record[1] -
                                                 table->record[0]));
      }
      triggers_info->old_field[i]= 0;

      List_iterator_fast<LEX_STRING> it(triggers_info->definitions_list);
      LEX_STRING *trg_create_str, *trg_name_str;
      char *trg_name_buff;
      LEX *old_lex= thd->lex, lex;

      thd->lex= &lex;

      while ((trg_create_str= it++))
      {
        lex_start(thd, (uchar*)trg_create_str->str, trg_create_str->length);
        mysql_init_query(thd, true);
        lex.trg_table= table;
        if (yyparse((void *)thd) || thd->is_fatal_error)
        {
          /*
            Free lex associated resources
            QQ: Do we really need all this stuff here ?
          */
          if (lex.sphead)
          {
            if (&lex != thd->lex)
              thd->lex->sphead->restore_lex(thd);
            delete lex.sphead;
          }
          goto err_with_lex_cleanup;
        }

        triggers_info->bodies[lex.trg_chistics.event]
                             [lex.trg_chistics.action_time]= lex.sphead;
        lex.sphead= 0;

        if (!(trg_name_buff= alloc_root(&table->mem_root,
                                        sizeof(LEX_STRING) +
                                        lex.name_and_length.length + 1)))
          goto err_with_lex_cleanup;

        trg_name_str= (LEX_STRING *)trg_name_buff;
        trg_name_buff+= sizeof(LEX_STRING);
        memcpy(trg_name_buff, lex.name_and_length.str,
               lex.name_and_length.length + 1);
        trg_name_str->str= trg_name_buff;
        trg_name_str->length= lex.name_and_length.length;

	old_global_mem_root= my_pthread_getspecific_ptr(MEM_ROOT*, THR_MALLOC);
	my_pthread_setspecific_ptr(THR_MALLOC, &table->mem_root);

        if (triggers_info->names_list.push_back(trg_name_str))
          goto err_with_lex_cleanup;

        my_pthread_setspecific_ptr(THR_MALLOC, old_global_mem_root);

        lex_end(&lex);
      }
      thd->lex= old_lex;

      DBUG_RETURN(0);

err_with_lex_cleanup:
      // QQ: anything else ?
      lex_end(&lex);
      thd->lex= old_lex;
      DBUG_RETURN(1);
    }

    /*
      We don't care about this error message much because .TRG files will
      be merged into .FRM anyway.
    */
    my_error(ER_WRONG_OBJECT, MYF(0), table_name, triggers_file_ext, "TRIGGER");
    DBUG_RETURN(1);
  }

  DBUG_RETURN(1);
}