1/*-------------------------------------------------------------------------
2 *
3 * rewriteDefine.c
4 * routines for defining a rewrite rule
5 *
6 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/rewrite/rewriteDefine.c
12 *
13 *-------------------------------------------------------------------------
14 */
15#include "postgres.h"
16
17#include "access/heapam.h"
18#include "access/htup_details.h"
19#include "access/multixact.h"
20#include "access/tableam.h"
21#include "access/transam.h"
22#include "access/xact.h"
23#include "catalog/catalog.h"
24#include "catalog/dependency.h"
25#include "catalog/heap.h"
26#include "catalog/indexing.h"
27#include "catalog/namespace.h"
28#include "catalog/objectaccess.h"
29#include "catalog/pg_rewrite.h"
30#include "catalog/storage.h"
31#include "commands/policy.h"
32#include "miscadmin.h"
33#include "nodes/nodeFuncs.h"
34#include "parser/parse_utilcmd.h"
35#include "rewrite/rewriteDefine.h"
36#include "rewrite/rewriteManip.h"
37#include "rewrite/rewriteSupport.h"
38#include "utils/acl.h"
39#include "utils/builtins.h"
40#include "utils/inval.h"
41#include "utils/lsyscache.h"
42#include "utils/rel.h"
43#include "utils/snapmgr.h"
44#include "utils/syscache.h"
45
46
47static void checkRuleResultList(List *targetList, TupleDesc resultDesc,
48 bool isSelect, bool requireColumnNameMatch);
49static bool setRuleCheckAsUser_walker(Node *node, Oid *context);
50static void setRuleCheckAsUser_Query(Query *qry, Oid userid);
51
52
53/*
54 * InsertRule -
55 * takes the arguments and inserts them as a row into the system
56 * relation "pg_rewrite"
57 */
58static Oid
59InsertRule(const char *rulname,
60 int evtype,
61 Oid eventrel_oid,
62 bool evinstead,
63 Node *event_qual,
64 List *action,
65 bool replace)
66{
67 char *evqual = nodeToString(event_qual);
68 char *actiontree = nodeToString((Node *) action);
69 Datum values[Natts_pg_rewrite];
70 bool nulls[Natts_pg_rewrite];
71 bool replaces[Natts_pg_rewrite];
72 NameData rname;
73 Relation pg_rewrite_desc;
74 HeapTuple tup,
75 oldtup;
76 Oid rewriteObjectId;
77 ObjectAddress myself,
78 referenced;
79 bool is_update = false;
80
81 /*
82 * Set up *nulls and *values arrays
83 */
84 MemSet(nulls, false, sizeof(nulls));
85
86 namestrcpy(&rname, rulname);
87 values[Anum_pg_rewrite_rulename - 1] = NameGetDatum(&rname);
88 values[Anum_pg_rewrite_ev_class - 1] = ObjectIdGetDatum(eventrel_oid);
89 values[Anum_pg_rewrite_ev_type - 1] = CharGetDatum(evtype + '0');
90 values[Anum_pg_rewrite_ev_enabled - 1] = CharGetDatum(RULE_FIRES_ON_ORIGIN);
91 values[Anum_pg_rewrite_is_instead - 1] = BoolGetDatum(evinstead);
92 values[Anum_pg_rewrite_ev_qual - 1] = CStringGetTextDatum(evqual);
93 values[Anum_pg_rewrite_ev_action - 1] = CStringGetTextDatum(actiontree);
94
95 /*
96 * Ready to store new pg_rewrite tuple
97 */
98 pg_rewrite_desc = table_open(RewriteRelationId, RowExclusiveLock);
99
100 /*
101 * Check to see if we are replacing an existing tuple
102 */
103 oldtup = SearchSysCache2(RULERELNAME,
104 ObjectIdGetDatum(eventrel_oid),
105 PointerGetDatum(rulname));
106
107 if (HeapTupleIsValid(oldtup))
108 {
109 if (!replace)
110 ereport(ERROR,
111 (errcode(ERRCODE_DUPLICATE_OBJECT),
112 errmsg("rule \"%s\" for relation \"%s\" already exists",
113 rulname, get_rel_name(eventrel_oid))));
114
115 /*
116 * When replacing, we don't need to replace every attribute
117 */
118 MemSet(replaces, false, sizeof(replaces));
119 replaces[Anum_pg_rewrite_ev_type - 1] = true;
120 replaces[Anum_pg_rewrite_is_instead - 1] = true;
121 replaces[Anum_pg_rewrite_ev_qual - 1] = true;
122 replaces[Anum_pg_rewrite_ev_action - 1] = true;
123
124 tup = heap_modify_tuple(oldtup, RelationGetDescr(pg_rewrite_desc),
125 values, nulls, replaces);
126
127 CatalogTupleUpdate(pg_rewrite_desc, &tup->t_self, tup);
128
129 ReleaseSysCache(oldtup);
130
131 rewriteObjectId = ((Form_pg_rewrite) GETSTRUCT(tup))->oid;
132 is_update = true;
133 }
134 else
135 {
136 rewriteObjectId = GetNewOidWithIndex(pg_rewrite_desc,
137 RewriteOidIndexId,
138 Anum_pg_rewrite_oid);
139 values[Anum_pg_rewrite_oid - 1] = ObjectIdGetDatum(rewriteObjectId);
140
141 tup = heap_form_tuple(pg_rewrite_desc->rd_att, values, nulls);
142
143 CatalogTupleInsert(pg_rewrite_desc, tup);
144 }
145
146
147 heap_freetuple(tup);
148
149 /* If replacing, get rid of old dependencies and make new ones */
150 if (is_update)
151 deleteDependencyRecordsFor(RewriteRelationId, rewriteObjectId, false);
152
153 /*
154 * Install dependency on rule's relation to ensure it will go away on
155 * relation deletion. If the rule is ON SELECT, make the dependency
156 * implicit --- this prevents deleting a view's SELECT rule. Other kinds
157 * of rules can be AUTO.
158 */
159 myself.classId = RewriteRelationId;
160 myself.objectId = rewriteObjectId;
161 myself.objectSubId = 0;
162
163 referenced.classId = RelationRelationId;
164 referenced.objectId = eventrel_oid;
165 referenced.objectSubId = 0;
166
167 recordDependencyOn(&myself, &referenced,
168 (evtype == CMD_SELECT) ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO);
169
170 /*
171 * Also install dependencies on objects referenced in action and qual.
172 */
173 recordDependencyOnExpr(&myself, (Node *) action, NIL,
174 DEPENDENCY_NORMAL);
175
176 if (event_qual != NULL)
177 {
178 /* Find query containing OLD/NEW rtable entries */
179 Query *qry = linitial_node(Query, action);
180
181 qry = getInsertSelectQuery(qry, NULL);
182 recordDependencyOnExpr(&myself, event_qual, qry->rtable,
183 DEPENDENCY_NORMAL);
184 }
185
186 /* Post creation hook for new rule */
187 InvokeObjectPostCreateHook(RewriteRelationId, rewriteObjectId, 0);
188
189 table_close(pg_rewrite_desc, RowExclusiveLock);
190
191 return rewriteObjectId;
192}
193
194/*
195 * DefineRule
196 * Execute a CREATE RULE command.
197 */
198ObjectAddress
199DefineRule(RuleStmt *stmt, const char *queryString)
200{
201 List *actions;
202 Node *whereClause;
203 Oid relId;
204
205 /* Parse analysis. */
206 transformRuleStmt(stmt, queryString, &actions, &whereClause);
207
208 /*
209 * Find and lock the relation. Lock level should match
210 * DefineQueryRewrite.
211 */
212 relId = RangeVarGetRelid(stmt->relation, AccessExclusiveLock, false);
213
214 /* ... and execute */
215 return DefineQueryRewrite(stmt->rulename,
216 relId,
217 whereClause,
218 stmt->event,
219 stmt->instead,
220 stmt->replace,
221 actions);
222}
223
224
225/*
226 * DefineQueryRewrite
227 * Create a rule
228 *
229 * This is essentially the same as DefineRule() except that the rule's
230 * action and qual have already been passed through parse analysis.
231 */
232ObjectAddress
233DefineQueryRewrite(const char *rulename,
234 Oid event_relid,
235 Node *event_qual,
236 CmdType event_type,
237 bool is_instead,
238 bool replace,
239 List *action)
240{
241 Relation event_relation;
242 ListCell *l;
243 Query *query;
244 bool RelisBecomingView = false;
245 Oid ruleId = InvalidOid;
246 ObjectAddress address;
247
248 /*
249 * If we are installing an ON SELECT rule, we had better grab
250 * AccessExclusiveLock to ensure no SELECTs are currently running on the
251 * event relation. For other types of rules, it would be sufficient to
252 * grab ShareRowExclusiveLock to lock out insert/update/delete actions and
253 * to ensure that we lock out current CREATE RULE statements; but because
254 * of race conditions in access to catalog entries, we can't do that yet.
255 *
256 * Note that this lock level should match the one used in DefineRule.
257 */
258 event_relation = table_open(event_relid, AccessExclusiveLock);
259
260 /*
261 * Verify relation is of a type that rules can sensibly be applied to.
262 * Internal callers can target materialized views, but transformRuleStmt()
263 * blocks them for users. Don't mention them in the error message.
264 */
265 if (event_relation->rd_rel->relkind != RELKIND_RELATION &&
266 event_relation->rd_rel->relkind != RELKIND_MATVIEW &&
267 event_relation->rd_rel->relkind != RELKIND_VIEW &&
268 event_relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
269 ereport(ERROR,
270 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
271 errmsg("\"%s\" is not a table or view",
272 RelationGetRelationName(event_relation))));
273
274 if (!allowSystemTableMods && IsSystemRelation(event_relation))
275 ereport(ERROR,
276 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
277 errmsg("permission denied: \"%s\" is a system catalog",
278 RelationGetRelationName(event_relation))));
279
280 /*
281 * Check user has permission to apply rules to this relation.
282 */
283 if (!pg_class_ownercheck(event_relid, GetUserId()))
284 aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(event_relation->rd_rel->relkind),
285 RelationGetRelationName(event_relation));
286
287 /*
288 * No rule actions that modify OLD or NEW
289 */
290 foreach(l, action)
291 {
292 query = lfirst_node(Query, l);
293 if (query->resultRelation == 0)
294 continue;
295 /* Don't be fooled by INSERT/SELECT */
296 if (query != getInsertSelectQuery(query, NULL))
297 continue;
298 if (query->resultRelation == PRS2_OLD_VARNO)
299 ereport(ERROR,
300 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
301 errmsg("rule actions on OLD are not implemented"),
302 errhint("Use views or triggers instead.")));
303 if (query->resultRelation == PRS2_NEW_VARNO)
304 ereport(ERROR,
305 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
306 errmsg("rule actions on NEW are not implemented"),
307 errhint("Use triggers instead.")));
308 }
309
310 if (event_type == CMD_SELECT)
311 {
312 /*
313 * Rules ON SELECT are restricted to view definitions
314 *
315 * So there cannot be INSTEAD NOTHING, ...
316 */
317 if (list_length(action) == 0)
318 ereport(ERROR,
319 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
320 errmsg("INSTEAD NOTHING rules on SELECT are not implemented"),
321 errhint("Use views instead.")));
322
323 /*
324 * ... there cannot be multiple actions, ...
325 */
326 if (list_length(action) > 1)
327 ereport(ERROR,
328 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
329 errmsg("multiple actions for rules on SELECT are not implemented")));
330
331 /*
332 * ... the one action must be a SELECT, ...
333 */
334 query = linitial_node(Query, action);
335 if (!is_instead ||
336 query->commandType != CMD_SELECT)
337 ereport(ERROR,
338 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
339 errmsg("rules on SELECT must have action INSTEAD SELECT")));
340
341 /*
342 * ... it cannot contain data-modifying WITH ...
343 */
344 if (query->hasModifyingCTE)
345 ereport(ERROR,
346 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
347 errmsg("rules on SELECT must not contain data-modifying statements in WITH")));
348
349 /*
350 * ... there can be no rule qual, ...
351 */
352 if (event_qual != NULL)
353 ereport(ERROR,
354 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
355 errmsg("event qualifications are not implemented for rules on SELECT")));
356
357 /*
358 * ... the targetlist of the SELECT action must exactly match the
359 * event relation, ...
360 */
361 checkRuleResultList(query->targetList,
362 RelationGetDescr(event_relation),
363 true,
364 event_relation->rd_rel->relkind !=
365 RELKIND_MATVIEW);
366
367 /*
368 * ... there must not be another ON SELECT rule already ...
369 */
370 if (!replace && event_relation->rd_rules != NULL)
371 {
372 int i;
373
374 for (i = 0; i < event_relation->rd_rules->numLocks; i++)
375 {
376 RewriteRule *rule;
377
378 rule = event_relation->rd_rules->rules[i];
379 if (rule->event == CMD_SELECT)
380 ereport(ERROR,
381 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
382 errmsg("\"%s\" is already a view",
383 RelationGetRelationName(event_relation))));
384 }
385 }
386
387 /*
388 * ... and finally the rule must be named _RETURN.
389 */
390 if (strcmp(rulename, ViewSelectRuleName) != 0)
391 {
392 /*
393 * In versions before 7.3, the expected name was _RETviewname. For
394 * backwards compatibility with old pg_dump output, accept that
395 * and silently change it to _RETURN. Since this is just a quick
396 * backwards-compatibility hack, limit the number of characters
397 * checked to a few less than NAMEDATALEN; this saves having to
398 * worry about where a multibyte character might have gotten
399 * truncated.
400 */
401 if (strncmp(rulename, "_RET", 4) != 0 ||
402 strncmp(rulename + 4, RelationGetRelationName(event_relation),
403 NAMEDATALEN - 4 - 4) != 0)
404 ereport(ERROR,
405 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
406 errmsg("view rule for \"%s\" must be named \"%s\"",
407 RelationGetRelationName(event_relation),
408 ViewSelectRuleName)));
409 rulename = pstrdup(ViewSelectRuleName);
410 }
411
412 /*
413 * Are we converting a relation to a view?
414 *
415 * If so, check that the relation is empty because the storage for the
416 * relation is going to be deleted. Also insist that the rel not have
417 * any triggers, indexes, child tables, policies, or RLS enabled.
418 * (Note: these tests are too strict, because they will reject
419 * relations that once had such but don't anymore. But we don't
420 * really care, because this whole business of converting relations to
421 * views is just a kluge to allow dump/reload of views that
422 * participate in circular dependencies.)
423 */
424 if (event_relation->rd_rel->relkind != RELKIND_VIEW &&
425 event_relation->rd_rel->relkind != RELKIND_MATVIEW)
426 {
427 TableScanDesc scanDesc;
428 Snapshot snapshot;
429 TupleTableSlot *slot;
430
431 if (event_relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
432 ereport(ERROR,
433 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
434 errmsg("cannot convert partitioned table \"%s\" to a view",
435 RelationGetRelationName(event_relation))));
436
437 if (event_relation->rd_rel->relispartition)
438 ereport(ERROR,
439 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
440 errmsg("cannot convert partition \"%s\" to a view",
441 RelationGetRelationName(event_relation))));
442
443 snapshot = RegisterSnapshot(GetLatestSnapshot());
444 scanDesc = table_beginscan(event_relation, snapshot, 0, NULL);
445 slot = table_slot_create(event_relation, NULL);
446 if (table_scan_getnextslot(scanDesc, ForwardScanDirection, slot))
447 ereport(ERROR,
448 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
449 errmsg("could not convert table \"%s\" to a view because it is not empty",
450 RelationGetRelationName(event_relation))));
451 ExecDropSingleTupleTableSlot(slot);
452 table_endscan(scanDesc);
453 UnregisterSnapshot(snapshot);
454
455 if (event_relation->rd_rel->relhastriggers)
456 ereport(ERROR,
457 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
458 errmsg("could not convert table \"%s\" to a view because it has triggers",
459 RelationGetRelationName(event_relation)),
460 errhint("In particular, the table cannot be involved in any foreign key relationships.")));
461
462 if (event_relation->rd_rel->relhasindex)
463 ereport(ERROR,
464 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
465 errmsg("could not convert table \"%s\" to a view because it has indexes",
466 RelationGetRelationName(event_relation))));
467
468 if (event_relation->rd_rel->relhassubclass)
469 ereport(ERROR,
470 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
471 errmsg("could not convert table \"%s\" to a view because it has child tables",
472 RelationGetRelationName(event_relation))));
473
474 if (event_relation->rd_rel->relrowsecurity)
475 ereport(ERROR,
476 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
477 errmsg("could not convert table \"%s\" to a view because it has row security enabled",
478 RelationGetRelationName(event_relation))));
479
480 if (relation_has_policies(event_relation))
481 ereport(ERROR,
482 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
483 errmsg("could not convert table \"%s\" to a view because it has row security policies",
484 RelationGetRelationName(event_relation))));
485
486 RelisBecomingView = true;
487 }
488 }
489 else
490 {
491 /*
492 * For non-SELECT rules, a RETURNING list can appear in at most one of
493 * the actions ... and there can't be any RETURNING list at all in a
494 * conditional or non-INSTEAD rule. (Actually, there can be at most
495 * one RETURNING list across all rules on the same event, but it seems
496 * best to enforce that at rule expansion time.) If there is a
497 * RETURNING list, it must match the event relation.
498 */
499 bool haveReturning = false;
500
501 foreach(l, action)
502 {
503 query = lfirst_node(Query, l);
504
505 if (!query->returningList)
506 continue;
507 if (haveReturning)
508 ereport(ERROR,
509 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
510 errmsg("cannot have multiple RETURNING lists in a rule")));
511 haveReturning = true;
512 if (event_qual != NULL)
513 ereport(ERROR,
514 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
515 errmsg("RETURNING lists are not supported in conditional rules")));
516 if (!is_instead)
517 ereport(ERROR,
518 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
519 errmsg("RETURNING lists are not supported in non-INSTEAD rules")));
520 checkRuleResultList(query->returningList,
521 RelationGetDescr(event_relation),
522 false, false);
523 }
524 }
525
526 /*
527 * This rule is allowed - prepare to install it.
528 */
529
530 /* discard rule if it's null action and not INSTEAD; it's a no-op */
531 if (action != NIL || is_instead)
532 {
533 ruleId = InsertRule(rulename,
534 event_type,
535 event_relid,
536 is_instead,
537 event_qual,
538 action,
539 replace);
540
541 /*
542 * Set pg_class 'relhasrules' field true for event relation.
543 *
544 * Important side effect: an SI notice is broadcast to force all
545 * backends (including me!) to update relcache entries with the new
546 * rule.
547 */
548 SetRelationRuleStatus(event_relid, true);
549 }
550
551 /* ---------------------------------------------------------------------
552 * If the relation is becoming a view:
553 * - delete the associated storage files
554 * - get rid of any system attributes in pg_attribute; a view shouldn't
555 * have any of those
556 * - remove the toast table; there is no need for it anymore, and its
557 * presence would make vacuum slightly more complicated
558 * - set relkind to RELKIND_VIEW, and adjust other pg_class fields
559 * to be appropriate for a view
560 *
561 * NB: we had better have AccessExclusiveLock to do this ...
562 * ---------------------------------------------------------------------
563 */
564 if (RelisBecomingView)
565 {
566 Relation relationRelation;
567 Oid toastrelid;
568 HeapTuple classTup;
569 Form_pg_class classForm;
570
571 relationRelation = table_open(RelationRelationId, RowExclusiveLock);
572 toastrelid = event_relation->rd_rel->reltoastrelid;
573
574 /* drop storage while table still looks like a table */
575 RelationDropStorage(event_relation);
576 DeleteSystemAttributeTuples(event_relid);
577
578 /*
579 * Drop the toast table if any. (This won't take care of updating the
580 * toast fields in the relation's own pg_class entry; we handle that
581 * below.)
582 */
583 if (OidIsValid(toastrelid))
584 {
585 ObjectAddress toastobject;
586
587 /*
588 * Delete the dependency of the toast relation on the main
589 * relation so we can drop the former without dropping the latter.
590 */
591 deleteDependencyRecordsFor(RelationRelationId, toastrelid,
592 false);
593
594 /* Make deletion of dependency record visible */
595 CommandCounterIncrement();
596
597 /* Now drop toast table, including its index */
598 toastobject.classId = RelationRelationId;
599 toastobject.objectId = toastrelid;
600 toastobject.objectSubId = 0;
601 performDeletion(&toastobject, DROP_RESTRICT,
602 PERFORM_DELETION_INTERNAL);
603 }
604
605 /*
606 * SetRelationRuleStatus may have updated the pg_class row, so we must
607 * advance the command counter before trying to update it again.
608 */
609 CommandCounterIncrement();
610
611 /*
612 * Fix pg_class entry to look like a normal view's, including setting
613 * the correct relkind and removal of reltoastrelid of the toast table
614 * we potentially removed above.
615 */
616 classTup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(event_relid));
617 if (!HeapTupleIsValid(classTup))
618 elog(ERROR, "cache lookup failed for relation %u", event_relid);
619 classForm = (Form_pg_class) GETSTRUCT(classTup);
620
621 classForm->relam = InvalidOid;
622 classForm->reltablespace = InvalidOid;
623 classForm->relpages = 0;
624 classForm->reltuples = 0;
625 classForm->relallvisible = 0;
626 classForm->reltoastrelid = InvalidOid;
627 classForm->relhasindex = false;
628 classForm->relkind = RELKIND_VIEW;
629 classForm->relfrozenxid = InvalidTransactionId;
630 classForm->relminmxid = InvalidMultiXactId;
631 classForm->relreplident = REPLICA_IDENTITY_NOTHING;
632
633 CatalogTupleUpdate(relationRelation, &classTup->t_self, classTup);
634
635 heap_freetuple(classTup);
636 table_close(relationRelation, RowExclusiveLock);
637 }
638
639 ObjectAddressSet(address, RewriteRelationId, ruleId);
640
641 /* Close rel, but keep lock till commit... */
642 table_close(event_relation, NoLock);
643
644 return address;
645}
646
647/*
648 * checkRuleResultList
649 * Verify that targetList produces output compatible with a tupledesc
650 *
651 * The targetList might be either a SELECT targetlist, or a RETURNING list;
652 * isSelect tells which. This is used for choosing error messages.
653 *
654 * A SELECT targetlist may optionally require that column names match.
655 */
656static void
657checkRuleResultList(List *targetList, TupleDesc resultDesc, bool isSelect,
658 bool requireColumnNameMatch)
659{
660 ListCell *tllist;
661 int i;
662
663 /* Only a SELECT may require a column name match. */
664 Assert(isSelect || !requireColumnNameMatch);
665
666 i = 0;
667 foreach(tllist, targetList)
668 {
669 TargetEntry *tle = (TargetEntry *) lfirst(tllist);
670 Oid tletypid;
671 int32 tletypmod;
672 Form_pg_attribute attr;
673 char *attname;
674
675 /* resjunk entries may be ignored */
676 if (tle->resjunk)
677 continue;
678 i++;
679 if (i > resultDesc->natts)
680 ereport(ERROR,
681 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
682 isSelect ?
683 errmsg("SELECT rule's target list has too many entries") :
684 errmsg("RETURNING list has too many entries")));
685
686 attr = TupleDescAttr(resultDesc, i - 1);
687 attname = NameStr(attr->attname);
688
689 /*
690 * Disallow dropped columns in the relation. This is not really
691 * expected to happen when creating an ON SELECT rule. It'd be
692 * possible if someone tried to convert a relation with dropped
693 * columns to a view, but the only case we care about supporting
694 * table-to-view conversion for is pg_dump, and pg_dump won't do that.
695 *
696 * Unfortunately, the situation is also possible when adding a rule
697 * with RETURNING to a regular table, and rejecting that case is
698 * altogether more annoying. In principle we could support it by
699 * modifying the targetlist to include dummy NULL columns
700 * corresponding to the dropped columns in the tupdesc. However,
701 * places like ruleutils.c would have to be fixed to not process such
702 * entries, and that would take an uncertain and possibly rather large
703 * amount of work. (Note we could not dodge that by marking the dummy
704 * columns resjunk, since it's precisely the non-resjunk tlist columns
705 * that are expected to correspond to table columns.)
706 */
707 if (attr->attisdropped)
708 ereport(ERROR,
709 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
710 isSelect ?
711 errmsg("cannot convert relation containing dropped columns to view") :
712 errmsg("cannot create a RETURNING list for a relation containing dropped columns")));
713
714 /* Check name match if required; no need for two error texts here */
715 if (requireColumnNameMatch && strcmp(tle->resname, attname) != 0)
716 ereport(ERROR,
717 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
718 errmsg("SELECT rule's target entry %d has different column name from column \"%s\"",
719 i, attname),
720 errdetail("SELECT target entry is named \"%s\".",
721 tle->resname)));
722
723 /* Check type match. */
724 tletypid = exprType((Node *) tle->expr);
725 if (attr->atttypid != tletypid)
726 ereport(ERROR,
727 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
728 isSelect ?
729 errmsg("SELECT rule's target entry %d has different type from column \"%s\"",
730 i, attname) :
731 errmsg("RETURNING list's entry %d has different type from column \"%s\"",
732 i, attname),
733 isSelect ?
734 errdetail("SELECT target entry has type %s, but column has type %s.",
735 format_type_be(tletypid),
736 format_type_be(attr->atttypid)) :
737 errdetail("RETURNING list entry has type %s, but column has type %s.",
738 format_type_be(tletypid),
739 format_type_be(attr->atttypid))));
740
741 /*
742 * Allow typmods to be different only if one of them is -1, ie,
743 * "unspecified". This is necessary for cases like "numeric", where
744 * the table will have a filled-in default length but the select
745 * rule's expression will probably have typmod = -1.
746 */
747 tletypmod = exprTypmod((Node *) tle->expr);
748 if (attr->atttypmod != tletypmod &&
749 attr->atttypmod != -1 && tletypmod != -1)
750 ereport(ERROR,
751 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
752 isSelect ?
753 errmsg("SELECT rule's target entry %d has different size from column \"%s\"",
754 i, attname) :
755 errmsg("RETURNING list's entry %d has different size from column \"%s\"",
756 i, attname),
757 isSelect ?
758 errdetail("SELECT target entry has type %s, but column has type %s.",
759 format_type_with_typemod(tletypid, tletypmod),
760 format_type_with_typemod(attr->atttypid,
761 attr->atttypmod)) :
762 errdetail("RETURNING list entry has type %s, but column has type %s.",
763 format_type_with_typemod(tletypid, tletypmod),
764 format_type_with_typemod(attr->atttypid,
765 attr->atttypmod))));
766 }
767
768 if (i != resultDesc->natts)
769 ereport(ERROR,
770 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
771 isSelect ?
772 errmsg("SELECT rule's target list has too few entries") :
773 errmsg("RETURNING list has too few entries")));
774}
775
776/*
777 * setRuleCheckAsUser
778 * Recursively scan a query or expression tree and set the checkAsUser
779 * field to the given userid in all rtable entries.
780 *
781 * Note: for a view (ON SELECT rule), the checkAsUser field of the OLD
782 * RTE entry will be overridden when the view rule is expanded, and the
783 * checkAsUser field of the NEW entry is irrelevant because that entry's
784 * requiredPerms bits will always be zero. However, for other types of rules
785 * it's important to set these fields to match the rule owner. So we just set
786 * them always.
787 */
788void
789setRuleCheckAsUser(Node *node, Oid userid)
790{
791 (void) setRuleCheckAsUser_walker(node, &userid);
792}
793
794static bool
795setRuleCheckAsUser_walker(Node *node, Oid *context)
796{
797 if (node == NULL)
798 return false;
799 if (IsA(node, Query))
800 {
801 setRuleCheckAsUser_Query((Query *) node, *context);
802 return false;
803 }
804 return expression_tree_walker(node, setRuleCheckAsUser_walker,
805 (void *) context);
806}
807
808static void
809setRuleCheckAsUser_Query(Query *qry, Oid userid)
810{
811 ListCell *l;
812
813 /* Set all the RTEs in this query node */
814 foreach(l, qry->rtable)
815 {
816 RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
817
818 if (rte->rtekind == RTE_SUBQUERY)
819 {
820 /* Recurse into subquery in FROM */
821 setRuleCheckAsUser_Query(rte->subquery, userid);
822 }
823 else
824 rte->checkAsUser = userid;
825 }
826
827 /* Recurse into subquery-in-WITH */
828 foreach(l, qry->cteList)
829 {
830 CommonTableExpr *cte = (CommonTableExpr *) lfirst(l);
831
832 setRuleCheckAsUser_Query(castNode(Query, cte->ctequery), userid);
833 }
834
835 /* If there are sublinks, search for them and process their RTEs */
836 if (qry->hasSubLinks)
837 query_tree_walker(qry, setRuleCheckAsUser_walker, (void *) &userid,
838 QTW_IGNORE_RC_SUBQUERIES);
839}
840
841
842/*
843 * Change the firing semantics of an existing rule.
844 */
845void
846EnableDisableRule(Relation rel, const char *rulename,
847 char fires_when)
848{
849 Relation pg_rewrite_desc;
850 Oid owningRel = RelationGetRelid(rel);
851 Oid eventRelationOid;
852 HeapTuple ruletup;
853 Form_pg_rewrite ruleform;
854 bool changed = false;
855
856 /*
857 * Find the rule tuple to change.
858 */
859 pg_rewrite_desc = table_open(RewriteRelationId, RowExclusiveLock);
860 ruletup = SearchSysCacheCopy2(RULERELNAME,
861 ObjectIdGetDatum(owningRel),
862 PointerGetDatum(rulename));
863 if (!HeapTupleIsValid(ruletup))
864 ereport(ERROR,
865 (errcode(ERRCODE_UNDEFINED_OBJECT),
866 errmsg("rule \"%s\" for relation \"%s\" does not exist",
867 rulename, get_rel_name(owningRel))));
868
869 ruleform = (Form_pg_rewrite) GETSTRUCT(ruletup);
870
871 /*
872 * Verify that the user has appropriate permissions.
873 */
874 eventRelationOid = ruleform->ev_class;
875 Assert(eventRelationOid == owningRel);
876 if (!pg_class_ownercheck(eventRelationOid, GetUserId()))
877 aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(eventRelationOid)),
878 get_rel_name(eventRelationOid));
879
880 /*
881 * Change ev_enabled if it is different from the desired new state.
882 */
883 if (DatumGetChar(ruleform->ev_enabled) !=
884 fires_when)
885 {
886 ruleform->ev_enabled = CharGetDatum(fires_when);
887 CatalogTupleUpdate(pg_rewrite_desc, &ruletup->t_self, ruletup);
888
889 changed = true;
890 }
891
892 InvokeObjectPostAlterHook(RewriteRelationId, ruleform->oid, 0);
893
894 heap_freetuple(ruletup);
895 table_close(pg_rewrite_desc, RowExclusiveLock);
896
897 /*
898 * If we changed anything, broadcast a SI inval message to force each
899 * backend (including our own!) to rebuild relation's relcache entry.
900 * Otherwise they will fail to apply the change promptly.
901 */
902 if (changed)
903 CacheInvalidateRelcache(rel);
904}
905
906
907/*
908 * Perform permissions and integrity checks before acquiring a relation lock.
909 */
910static void
911RangeVarCallbackForRenameRule(const RangeVar *rv, Oid relid, Oid oldrelid,
912 void *arg)
913{
914 HeapTuple tuple;
915 Form_pg_class form;
916
917 tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
918 if (!HeapTupleIsValid(tuple))
919 return; /* concurrently dropped */
920 form = (Form_pg_class) GETSTRUCT(tuple);
921
922 /* only tables and views can have rules */
923 if (form->relkind != RELKIND_RELATION &&
924 form->relkind != RELKIND_VIEW &&
925 form->relkind != RELKIND_PARTITIONED_TABLE)
926 ereport(ERROR,
927 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
928 errmsg("\"%s\" is not a table or view", rv->relname)));
929
930 if (!allowSystemTableMods && IsSystemClass(relid, form))
931 ereport(ERROR,
932 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
933 errmsg("permission denied: \"%s\" is a system catalog",
934 rv->relname)));
935
936 /* you must own the table to rename one of its rules */
937 if (!pg_class_ownercheck(relid, GetUserId()))
938 aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), rv->relname);
939
940 ReleaseSysCache(tuple);
941}
942
943/*
944 * Rename an existing rewrite rule.
945 */
946ObjectAddress
947RenameRewriteRule(RangeVar *relation, const char *oldName,
948 const char *newName)
949{
950 Oid relid;
951 Relation targetrel;
952 Relation pg_rewrite_desc;
953 HeapTuple ruletup;
954 Form_pg_rewrite ruleform;
955 Oid ruleOid;
956 ObjectAddress address;
957
958 /*
959 * Look up name, check permissions, and acquire lock (which we will NOT
960 * release until end of transaction).
961 */
962 relid = RangeVarGetRelidExtended(relation, AccessExclusiveLock,
963 0,
964 RangeVarCallbackForRenameRule,
965 NULL);
966
967 /* Have lock already, so just need to build relcache entry. */
968 targetrel = relation_open(relid, NoLock);
969
970 /* Prepare to modify pg_rewrite */
971 pg_rewrite_desc = table_open(RewriteRelationId, RowExclusiveLock);
972
973 /* Fetch the rule's entry (it had better exist) */
974 ruletup = SearchSysCacheCopy2(RULERELNAME,
975 ObjectIdGetDatum(relid),
976 PointerGetDatum(oldName));
977 if (!HeapTupleIsValid(ruletup))
978 ereport(ERROR,
979 (errcode(ERRCODE_UNDEFINED_OBJECT),
980 errmsg("rule \"%s\" for relation \"%s\" does not exist",
981 oldName, RelationGetRelationName(targetrel))));
982 ruleform = (Form_pg_rewrite) GETSTRUCT(ruletup);
983 ruleOid = ruleform->oid;
984
985 /* rule with the new name should not already exist */
986 if (IsDefinedRewriteRule(relid, newName))
987 ereport(ERROR,
988 (errcode(ERRCODE_DUPLICATE_OBJECT),
989 errmsg("rule \"%s\" for relation \"%s\" already exists",
990 newName, RelationGetRelationName(targetrel))));
991
992 /*
993 * We disallow renaming ON SELECT rules, because they should always be
994 * named "_RETURN".
995 */
996 if (ruleform->ev_type == CMD_SELECT + '0')
997 ereport(ERROR,
998 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
999 errmsg("renaming an ON SELECT rule is not allowed")));
1000
1001 /* OK, do the update */
1002 namestrcpy(&(ruleform->rulename), newName);
1003
1004 CatalogTupleUpdate(pg_rewrite_desc, &ruletup->t_self, ruletup);
1005
1006 heap_freetuple(ruletup);
1007 table_close(pg_rewrite_desc, RowExclusiveLock);
1008
1009 /*
1010 * Invalidate relation's relcache entry so that other backends (and this
1011 * one too!) are sent SI message to make them rebuild relcache entries.
1012 * (Ideally this should happen automatically...)
1013 */
1014 CacheInvalidateRelcache(targetrel);
1015
1016 ObjectAddressSet(address, RewriteRelationId, ruleOid);
1017
1018 /*
1019 * Close rel, but keep exclusive lock!
1020 */
1021 relation_close(targetrel, NoLock);
1022
1023 return address;
1024}
1025