granicus.if.org Git - postgresql/blob - src/backend/rewrite/rewriteDefine.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * rewriteDefine.c
   4  *        routines for defining a rewrite rule
   5  *
   6  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.67 2002/04/18 20:01:09 tgl Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include "access/heapam.h"
  18 #include "catalog/catname.h"
  19 #include "catalog/indexing.h"
  20 #include "catalog/pg_rewrite.h"
  21 #include "commands/view.h"
  22 #include "miscadmin.h"
  23 #include "optimizer/clauses.h"
  24 #include "parser/parse_relation.h"
  25 #include "rewrite/rewriteDefine.h"
  26 #include "rewrite/rewriteManip.h"
  27 #include "rewrite/rewriteSupport.h"
  28 #include "storage/smgr.h"
  29 #include "utils/acl.h"
  30 #include "utils/builtins.h"
  31 #include "utils/syscache.h"
  32
  33
  34 static void setRuleCheckAsUser(Query *qry, Oid userid);
  35 static bool setRuleCheckAsUser_walker(Node *node, Oid *context);
  36
  37
  38 /*
  39  * InsertRule -
  40  *        takes the arguments and inserts them as a row into the system
  41  *        relation "pg_rewrite"
  42  */
  43 static Oid
  44 InsertRule(char *rulname,
  45                    int evtype,
  46                    Oid eventrel_oid,
  47                    AttrNumber evslot_index,
  48                    bool evinstead,
  49                    char *evqual,
  50                    char *actiontree)
  51 {
  52         int                     i;
  53         Datum           values[Natts_pg_rewrite];
  54         char            nulls[Natts_pg_rewrite];
  55         NameData        rname;
  56         Relation        pg_rewrite_desc;
  57         TupleDesc       tupDesc;
  58         HeapTuple       tup;
  59         Oid                     rewriteObjectId;
  60
  61         if (IsDefinedRewriteRule(eventrel_oid, rulname))
  62                 elog(ERROR, "Attempt to insert rule \"%s\" failed: already exists",
  63                          rulname);
  64
  65         /*
  66          * Set up *nulls and *values arrays
  67          */
  68         MemSet(nulls, ' ', sizeof(nulls));
  69
  70         i = 0;
  71         namestrcpy(&rname, rulname);
  72         values[i++] = NameGetDatum(&rname);                             /* rulename */
  73         values[i++] = ObjectIdGetDatum(eventrel_oid);   /* ev_class */
  74         values[i++] = Int16GetDatum(evslot_index);              /* ev_attr */
  75         values[i++] = CharGetDatum(evtype + '0');               /* ev_type */
  76         values[i++] = BoolGetDatum(evinstead);                  /* is_instead */
  77         values[i++] = DirectFunctionCall1(textin, CStringGetDatum(evqual));     /* ev_qual */
  78         values[i++] = DirectFunctionCall1(textin, CStringGetDatum(actiontree)); /* ev_action */
  79
  80         /*
  81          * create a new pg_rewrite tuple
  82          */
  83         pg_rewrite_desc = heap_openr(RewriteRelationName, RowExclusiveLock);
  84
  85         tupDesc = pg_rewrite_desc->rd_att;
  86
  87         tup = heap_formtuple(tupDesc,
  88                                                  values,
  89                                                  nulls);
  90
  91         heap_insert(pg_rewrite_desc, tup);
  92
  93         rewriteObjectId = tup->t_data->t_oid;
  94
  95         if (RelationGetForm(pg_rewrite_desc)->relhasindex)
  96         {
  97                 Relation        idescs[Num_pg_rewrite_indices];
  98
  99                 CatalogOpenIndices(Num_pg_rewrite_indices, Name_pg_rewrite_indices,
 100                                                    idescs);
 101                 CatalogIndexInsert(idescs, Num_pg_rewrite_indices, pg_rewrite_desc,
 102                                                    tup);
 103                 CatalogCloseIndices(Num_pg_rewrite_indices, idescs);
 104         }
 105
 106         heap_freetuple(tup);
 107
 108         heap_close(pg_rewrite_desc, RowExclusiveLock);
 109
 110         return rewriteObjectId;
 111 }
 112
 113 void
 114 DefineQueryRewrite(RuleStmt *stmt)
 115 {
 116         RangeVar   *event_obj = stmt->relation;
 117         Node       *event_qual = stmt->whereClause;
 118         CmdType         event_type = stmt->event;
 119         bool            is_instead = stmt->instead;
 120         List       *action = stmt->actions;
 121         Relation        event_relation;
 122         Oid                     ev_relid;
 123         Oid                     ruleId;
 124         int                     event_attno;
 125         Oid                     event_attype;
 126         char       *actionP,
 127                            *event_qualP;
 128         List       *l;
 129         Query      *query;
 130         int32           aclcheck_result;
 131         bool            RelisBecomingView = false;
 132
 133         /*
 134          * If we are installing an ON SELECT rule, we had better grab
 135          * AccessExclusiveLock to ensure no SELECTs are currently running on
 136          * the event relation.  For other types of rules, it might be
 137          * sufficient to grab ShareLock to lock out insert/update/delete
 138          * actions.  But for now, let's just grab AccessExclusiveLock all the
 139          * time.
 140          */
 141         event_relation = heap_openrv(event_obj, AccessExclusiveLock);
 142         ev_relid = RelationGetRelid(event_relation);
 143
 144         /*
 145          * Check user has permission to apply rules to this relation.
 146          */
 147         aclcheck_result = pg_class_aclcheck(ev_relid, GetUserId(), ACL_RULE);
 148         if (aclcheck_result != ACLCHECK_OK)
 149                 elog(ERROR, "%s: %s",
 150                          RelationGetRelationName(event_relation),
 151                          aclcheck_error_strings[aclcheck_result]);
 152
 153         /*
 154          * No rule actions that modify OLD or NEW
 155          */
 156         foreach(l, action)
 157         {
 158                 query = (Query *) lfirst(l);
 159                 if (query->resultRelation == 0)
 160                         continue;
 161                 /* Don't be fooled by INSERT/SELECT */
 162                 if (query != getInsertSelectQuery(query, NULL))
 163                         continue;
 164                 if (query->resultRelation == PRS2_OLD_VARNO)
 165                         elog(ERROR, "rule actions on OLD currently not supported"
 166                                  "\n\tuse views or triggers instead");
 167                 if (query->resultRelation == PRS2_NEW_VARNO)
 168                         elog(ERROR, "rule actions on NEW currently not supported"
 169                                  "\n\tuse triggers instead");
 170         }
 171
 172         /*
 173          * Rules ON SELECT are restricted to view definitions
 174          */
 175         if (event_type == CMD_SELECT)
 176         {
 177                 List       *tllist;
 178                 int                     i;
 179                 char       *expected_name;
 180
 181                 /*
 182                  * So there cannot be INSTEAD NOTHING, ...
 183                  */
 184                 if (length(action) == 0)
 185                 {
 186                         elog(ERROR, "instead nothing rules on select currently not supported"
 187                                  "\n\tuse views instead");
 188                 }
 189
 190                 /*
 191                  * ... there cannot be multiple actions, ...
 192                  */
 193                 if (length(action) > 1)
 194                         elog(ERROR, "multiple action rules on select currently not supported");
 195
 196                 /*
 197                  * ... the one action must be a SELECT, ...
 198                  */
 199                 query = (Query *) lfirst(action);
 200                 if (!is_instead || query->commandType != CMD_SELECT)
 201                         elog(ERROR, "only instead-select rules currently supported on select");
 202
 203                 /*
 204                  * ... there can be no rule qual, ...
 205                  */
 206                 if (event_qual != NULL)
 207                         elog(ERROR, "event qualifications not supported for rules on select");
 208
 209                 /*
 210                  * ... the targetlist of the SELECT action must exactly match the
 211                  * event relation, ...
 212                  */
 213                 i = 0;
 214                 foreach(tllist, query->targetList)
 215                 {
 216                         TargetEntry *tle = (TargetEntry *) lfirst(tllist);
 217                         Resdom     *resdom = tle->resdom;
 218                         Form_pg_attribute attr;
 219                         char       *attname;
 220
 221                         if (resdom->resjunk)
 222                                 continue;
 223                         i++;
 224                         if (i > event_relation->rd_att->natts)
 225                                 elog(ERROR, "select rule's target list has too many entries");
 226
 227                         attr = event_relation->rd_att->attrs[i - 1];
 228                         attname = NameStr(attr->attname);
 229
 230                         if (strcmp(resdom->resname, attname) != 0)
 231                                 elog(ERROR, "select rule's target entry %d has different column name from %s", i, attname);
 232
 233                         if (attr->atttypid != resdom->restype)
 234                                 elog(ERROR, "select rule's target entry %d has different type from attribute %s", i, attname);
 235
 236                         /*
 237                          * Allow typmods to be different only if one of them is -1,
 238                          * ie, "unspecified".  This is necessary for cases like
 239                          * "numeric", where the table will have a filled-in default
 240                          * length but the select rule's expression will probably have
 241                          * typmod = -1.
 242                          */
 243                         if (attr->atttypmod != resdom->restypmod &&
 244                                 attr->atttypmod != -1 && resdom->restypmod != -1)
 245                                 elog(ERROR, "select rule's target entry %d has different size from attribute %s", i, attname);
 246                 }
 247
 248                 if (i != event_relation->rd_att->natts)
 249                         elog(ERROR, "select rule's target list has too few entries");
 250
 251                 /*
 252                  * ... there must not be another ON SELECT rule already ...
 253                  */
 254                 if (event_relation->rd_rules != NULL)
 255                 {
 256                         for (i = 0; i < event_relation->rd_rules->numLocks; i++)
 257                         {
 258                                 RewriteRule *rule;
 259
 260                                 rule = event_relation->rd_rules->rules[i];
 261                                 if (rule->event == CMD_SELECT)
 262                                         elog(ERROR, "\"%s\" is already a view",
 263                                                  RelationGetRelationName(event_relation));
 264                         }
 265                 }
 266
 267                 /*
 268                  * ... and finally the rule must be named _RETviewname.
 269                  */
 270                 expected_name = MakeRetrieveViewRuleName(event_obj->relname);
 271                 if (strcmp(expected_name, stmt->rulename) != 0)
 272                 {
 273                         elog(ERROR, "view rule for \"%s\" must be named \"%s\"",
 274                                  event_obj->relname, expected_name);
 275                 }
 276                 pfree(expected_name);
 277
 278                 /*
 279                  * Are we converting a relation to a view?
 280                  *
 281                  * If so, check that the relation is empty because the storage for
 282                  * the relation is going to be deleted.
 283                  */
 284                 if (event_relation->rd_rel->relkind != RELKIND_VIEW)
 285                 {
 286                         HeapScanDesc scanDesc;
 287                         HeapTuple       tuple;
 288
 289                         scanDesc = heap_beginscan(event_relation, 0, SnapshotNow, 0, NULL);
 290                         tuple = heap_getnext(scanDesc, 0);
 291                         if (HeapTupleIsValid(tuple))
 292                                 elog(ERROR, "Relation \"%s\" is not empty. Cannot convert it to view",
 293                                          event_obj->relname);
 294
 295                         /*
 296                          * don't need heap_freetuple because we never got a valid
 297                          * tuple
 298                          */
 299                         heap_endscan(scanDesc);
 300
 301                         RelisBecomingView = true;
 302                 }
 303         }
 304
 305         /*
 306          * This rule is allowed - prepare to install it.
 307          */
 308         event_attno = -1;
 309         event_attype = InvalidOid;
 310
 311         /*
 312          * We want the rule's table references to be checked as though by the
 313          * rule owner, not the user referencing the rule.  Therefore, scan
 314          * through the rule's rtables and set the checkAsUser field on all
 315          * rtable entries.
 316          */
 317         foreach(l, action)
 318         {
 319                 query = (Query *) lfirst(l);
 320                 setRuleCheckAsUser(query, GetUserId());
 321         }
 322
 323         /* discard rule if it's null action and not INSTEAD; it's a no-op */
 324         if (action != NIL || is_instead)
 325         {
 326                 event_qualP = nodeToString(event_qual);
 327                 actionP = nodeToString(action);
 328
 329                 ruleId = InsertRule(stmt->rulename,
 330                                                         event_type,
 331                                                         ev_relid,
 332                                                         event_attno,
 333                                                         is_instead,
 334                                                         event_qualP,
 335                                                         actionP);
 336
 337                 /*
 338                  * Set pg_class 'relhasrules' field TRUE for event relation. If
 339                  * appropriate, also modify the 'relkind' field to show that the
 340                  * relation is now a view.
 341                  *
 342                  * Important side effect: an SI notice is broadcast to force all
 343                  * backends (including me!) to update relcache entries with the
 344                  * new rule.
 345                  */
 346                 SetRelationRuleStatus(ev_relid, true, RelisBecomingView);
 347         }
 348
 349         /*
 350          * IF the relation is becoming a view, delete the storage files
 351          * associated with it.  NB: we had better have AccessExclusiveLock to
 352          * do this ...
 353          */
 354         if (RelisBecomingView)
 355                 smgrunlink(DEFAULT_SMGR, event_relation);
 356
 357         /* Close rel, but keep lock till commit... */
 358         heap_close(event_relation, NoLock);
 359 }
 360
 361 /*
 362  * setRuleCheckAsUser
 363  *              Recursively scan a query and set the checkAsUser field to the
 364  *              given userid in all rtable entries.
 365  *
 366  * Note: for a view (ON SELECT rule), the checkAsUser field of the *OLD*
 367  * RTE entry will be overridden when the view rule is expanded, and the
 368  * checkAsUser field of the *NEW* entry is irrelevant because that entry's
 369  * checkFor bits will never be set.  However, for other types of rules it's
 370  * important to set these fields to match the rule owner.  So we just set
 371  * them always.
 372  */
 373 static void
 374 setRuleCheckAsUser(Query *qry, Oid userid)
 375 {
 376         List       *l;
 377
 378         /* Set all the RTEs in this query node */
 379         foreach(l, qry->rtable)
 380         {
 381                 RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
 382
 383                 if (rte->subquery)
 384                 {
 385                         /* Recurse into subquery in FROM */
 386                         setRuleCheckAsUser(rte->subquery, userid);
 387                 }
 388                 else
 389                         rte->checkAsUser = userid;
 390         }
 391
 392         /* If there are sublinks, search for them and process their RTEs */
 393         if (qry->hasSubLinks)
 394                 query_tree_walker(qry, setRuleCheckAsUser_walker, (void *) &userid,
 395                                                   false /* already did the ones in rtable */ );
 396 }
 397
 398 /*
 399  * Expression-tree walker to find sublink queries
 400  */
 401 static bool
 402 setRuleCheckAsUser_walker(Node *node, Oid *context)
 403 {
 404         if (node == NULL)
 405                 return false;
 406         if (IsA(node, Query))
 407         {
 408                 Query      *qry = (Query *) node;
 409
 410                 setRuleCheckAsUser(qry, *context);
 411                 return false;
 412         }
 413         return expression_tree_walker(node, setRuleCheckAsUser_walker,
 414                                                                   (void *) context);
 415 }
 416
 417
 418 /*
 419  * Rename an existing rewrite rule.
 420  *
 421  * There is not currently a user command to invoke this directly
 422  * (perhaps there should be).  But we need it anyway to rename the
 423  * ON SELECT rule associated with a view, when the view is renamed.
 424  */
 425 void
 426 RenameRewriteRule(Oid owningRel, const char *oldName,
 427                                   const char *newName)
 428 {
 429         Relation        pg_rewrite_desc;
 430         HeapTuple       ruletup;
 431
 432         pg_rewrite_desc = heap_openr(RewriteRelationName, RowExclusiveLock);
 433
 434         ruletup = SearchSysCacheCopy(RULERELNAME,
 435                                                                  ObjectIdGetDatum(owningRel),
 436                                                                  PointerGetDatum(oldName),
 437                                                                  0, 0);
 438         if (!HeapTupleIsValid(ruletup))
 439                 elog(ERROR, "RenameRewriteRule: rule \"%s\" does not exist", oldName);
 440
 441         /* should not already exist */
 442         if (IsDefinedRewriteRule(owningRel, newName))
 443                 elog(ERROR, "Attempt to rename rule \"%s\" failed: \"%s\" already exists",
 444                          oldName, newName);
 445
 446         namestrcpy(&(((Form_pg_rewrite) GETSTRUCT(ruletup))->rulename), newName);
 447
 448         simple_heap_update(pg_rewrite_desc, &ruletup->t_self, ruletup);
 449
 450         /* keep system catalog indices current */
 451         if (RelationGetForm(pg_rewrite_desc)->relhasindex)
 452         {
 453                 Relation        idescs[Num_pg_rewrite_indices];
 454
 455                 CatalogOpenIndices(Num_pg_rewrite_indices, Name_pg_rewrite_indices,
 456                                                    idescs);
 457                 CatalogIndexInsert(idescs, Num_pg_rewrite_indices, pg_rewrite_desc,
 458                                                    ruletup);
 459                 CatalogCloseIndices(Num_pg_rewrite_indices, idescs);
 460         }
 461
 462         heap_freetuple(ruletup);
 463         heap_close(pg_rewrite_desc, RowExclusiveLock);
 464 }