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postgres/src/backend/rewrite/rewriteDefine.c
Tom Lane b21615d1e9 Reject non-ON-SELECT rules that are named "_RETURN". 
DefineQueryRewrite() has long required that ON SELECT rules be named
"_RETURN".  But we overlooked the converse case: we should forbid
non-ON-SELECT rules that are named "_RETURN".  In particular this
prevents using CREATE OR REPLACE RULE to overwrite a view's _RETURN
rule with some other kind of rule, thereby breaking the view.

Per bug #17646 from Kui Liu.  Back-patch to all supported branches.

Discussion: https://postgr.es/m/17646-70c93cfa40365776@postgresql.org
2022-10-17 12:14:39 -04:00

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/*-------------------------------------------------------------------------
*
* rewriteDefine.c
* routines for defining a rewrite rule
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/rewrite/rewriteDefine.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/multixact.h"
#include "access/tableam.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_rewrite.h"
#include "catalog/storage.h"
#include "commands/policy.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "parser/parse_utilcmd.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteManip.h"
#include "rewrite/rewriteSupport.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
static void checkRuleResultList(List *targetList, TupleDesc resultDesc,
bool isSelect, bool requireColumnNameMatch);
static bool setRuleCheckAsUser_walker(Node *node, Oid *context);
static void setRuleCheckAsUser_Query(Query *qry, Oid userid);
/*
* InsertRule -
* takes the arguments and inserts them as a row into the system
* relation "pg_rewrite"
*/
static Oid
InsertRule(const char *rulname,
int evtype,
Oid eventrel_oid,
bool evinstead,
Node *event_qual,
List *action,
bool replace)
{
char *evqual = nodeToString(event_qual);
char *actiontree = nodeToString((Node *) action);
Datum values[Natts_pg_rewrite];
bool nulls[Natts_pg_rewrite];
bool replaces[Natts_pg_rewrite];
NameData rname;
Relation pg_rewrite_desc;
HeapTuple tup,
oldtup;
Oid rewriteObjectId;
ObjectAddress myself,
referenced;
bool is_update = false;
/*
* Set up *nulls and *values arrays
*/
MemSet(nulls, false, sizeof(nulls));
namestrcpy(&rname, rulname);
values[Anum_pg_rewrite_rulename - 1] = NameGetDatum(&rname);
values[Anum_pg_rewrite_ev_class - 1] = ObjectIdGetDatum(eventrel_oid);
values[Anum_pg_rewrite_ev_type - 1] = CharGetDatum(evtype + '0');
values[Anum_pg_rewrite_ev_enabled - 1] = CharGetDatum(RULE_FIRES_ON_ORIGIN);
values[Anum_pg_rewrite_is_instead - 1] = BoolGetDatum(evinstead);
values[Anum_pg_rewrite_ev_qual - 1] = CStringGetTextDatum(evqual);
values[Anum_pg_rewrite_ev_action - 1] = CStringGetTextDatum(actiontree);
/*
* Ready to store new pg_rewrite tuple
*/
pg_rewrite_desc = table_open(RewriteRelationId, RowExclusiveLock);
/*
* Check to see if we are replacing an existing tuple
*/
oldtup = SearchSysCache2(RULERELNAME,
ObjectIdGetDatum(eventrel_oid),
PointerGetDatum(rulname));
if (HeapTupleIsValid(oldtup))
{
if (!replace)
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("rule \"%s\" for relation \"%s\" already exists",
rulname, get_rel_name(eventrel_oid))));
/*
* When replacing, we don't need to replace every attribute
*/
MemSet(replaces, false, sizeof(replaces));
replaces[Anum_pg_rewrite_ev_type - 1] = true;
replaces[Anum_pg_rewrite_is_instead - 1] = true;
replaces[Anum_pg_rewrite_ev_qual - 1] = true;
replaces[Anum_pg_rewrite_ev_action - 1] = true;
tup = heap_modify_tuple(oldtup, RelationGetDescr(pg_rewrite_desc),
values, nulls, replaces);
CatalogTupleUpdate(pg_rewrite_desc, &tup->t_self, tup);
ReleaseSysCache(oldtup);
rewriteObjectId = ((Form_pg_rewrite) GETSTRUCT(tup))->oid;
is_update = true;
}
else
{
rewriteObjectId = GetNewOidWithIndex(pg_rewrite_desc,
RewriteOidIndexId,
Anum_pg_rewrite_oid);
values[Anum_pg_rewrite_oid - 1] = ObjectIdGetDatum(rewriteObjectId);
tup = heap_form_tuple(pg_rewrite_desc->rd_att, values, nulls);
CatalogTupleInsert(pg_rewrite_desc, tup);
}
heap_freetuple(tup);
/* If replacing, get rid of old dependencies and make new ones */
if (is_update)
deleteDependencyRecordsFor(RewriteRelationId, rewriteObjectId, false);
/*
* Install dependency on rule's relation to ensure it will go away on
* relation deletion. If the rule is ON SELECT, make the dependency
* implicit --- this prevents deleting a view's SELECT rule. Other kinds
* of rules can be AUTO.
*/
myself.classId = RewriteRelationId;
myself.objectId = rewriteObjectId;
myself.objectSubId = 0;
referenced.classId = RelationRelationId;
referenced.objectId = eventrel_oid;
referenced.objectSubId = 0;
recordDependencyOn(&myself, &referenced,
(evtype == CMD_SELECT) ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO);
/*
* Also install dependencies on objects referenced in action and qual.
*/
recordDependencyOnExpr(&myself, (Node *) action, NIL,
DEPENDENCY_NORMAL);
if (event_qual != NULL)
{
/* Find query containing OLD/NEW rtable entries */
Query *qry = linitial_node(Query, action);
qry = getInsertSelectQuery(qry, NULL);
recordDependencyOnExpr(&myself, event_qual, qry->rtable,
DEPENDENCY_NORMAL);
}
/* Post creation hook for new rule */
InvokeObjectPostCreateHook(RewriteRelationId, rewriteObjectId, 0);
table_close(pg_rewrite_desc, RowExclusiveLock);
return rewriteObjectId;
}
/*
* DefineRule
* Execute a CREATE RULE command.
*/
ObjectAddress
DefineRule(RuleStmt *stmt, const char *queryString)
{
List *actions;
Node *whereClause;
Oid relId;
/* Parse analysis. */
transformRuleStmt(stmt, queryString, &actions, &whereClause);
/*
* Find and lock the relation. Lock level should match
* DefineQueryRewrite.
*/
relId = RangeVarGetRelid(stmt->relation, AccessExclusiveLock, false);
/* ... and execute */
return DefineQueryRewrite(stmt->rulename,
relId,
whereClause,
stmt->event,
stmt->instead,
stmt->replace,
actions);
}
/*
* DefineQueryRewrite
* Create a rule
*
* This is essentially the same as DefineRule() except that the rule's
* action and qual have already been passed through parse analysis.
*/
ObjectAddress
DefineQueryRewrite(const char *rulename,
Oid event_relid,
Node *event_qual,
CmdType event_type,
bool is_instead,
bool replace,
List *action)
{
Relation event_relation;
ListCell *l;
Query *query;
bool RelisBecomingView = false;
Oid ruleId = InvalidOid;
ObjectAddress address;
/*
* If we are installing an ON SELECT rule, we had better grab
* AccessExclusiveLock to ensure no SELECTs are currently running on the
* event relation. For other types of rules, it would be sufficient to
* grab ShareRowExclusiveLock to lock out insert/update/delete actions and
* to ensure that we lock out current CREATE RULE statements; but because
* of race conditions in access to catalog entries, we can't do that yet.
*
* Note that this lock level should match the one used in DefineRule.
*/
event_relation = table_open(event_relid, AccessExclusiveLock);
/*
* Verify relation is of a type that rules can sensibly be applied to.
* Internal callers can target materialized views, but transformRuleStmt()
* blocks them for users. Don't mention them in the error message.
*/
if (event_relation->rd_rel->relkind != RELKIND_RELATION &&
event_relation->rd_rel->relkind != RELKIND_MATVIEW &&
event_relation->rd_rel->relkind != RELKIND_VIEW &&
event_relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("\"%s\" is not a table or view",
RelationGetRelationName(event_relation))));
if (!allowSystemTableMods && IsSystemRelation(event_relation))
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied: \"%s\" is a system catalog",
RelationGetRelationName(event_relation))));
/*
* Check user has permission to apply rules to this relation.
*/
if (!pg_class_ownercheck(event_relid, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(event_relation->rd_rel->relkind),
RelationGetRelationName(event_relation));
/*
* No rule actions that modify OLD or NEW
*/
foreach(l, action)
{
query = lfirst_node(Query, l);
if (query->resultRelation == 0)
continue;
/* Don't be fooled by INSERT/SELECT */
if (query != getInsertSelectQuery(query, NULL))
continue;
if (query->resultRelation == PRS2_OLD_VARNO)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("rule actions on OLD are not implemented"),
errhint("Use views or triggers instead.")));
if (query->resultRelation == PRS2_NEW_VARNO)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("rule actions on NEW are not implemented"),
errhint("Use triggers instead.")));
}
if (event_type == CMD_SELECT)
{
/*
* Rules ON SELECT are restricted to view definitions
*
* So there cannot be INSTEAD NOTHING, ...
*/
if (list_length(action) == 0)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("INSTEAD NOTHING rules on SELECT are not implemented"),
errhint("Use views instead.")));
/*
* ... there cannot be multiple actions, ...
*/
if (list_length(action) > 1)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("multiple actions for rules on SELECT are not implemented")));
/*
* ... the one action must be a SELECT, ...
*/
query = linitial_node(Query, action);
if (!is_instead ||
query->commandType != CMD_SELECT)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("rules on SELECT must have action INSTEAD SELECT")));
/*
* ... it cannot contain data-modifying WITH ...
*/
if (query->hasModifyingCTE)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("rules on SELECT must not contain data-modifying statements in WITH")));
/*
* ... there can be no rule qual, ...
*/
if (event_qual != NULL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("event qualifications are not implemented for rules on SELECT")));
/*
* ... the targetlist of the SELECT action must exactly match the
* event relation, ...
*/
checkRuleResultList(query->targetList,
RelationGetDescr(event_relation),
true,
event_relation->rd_rel->relkind !=
RELKIND_MATVIEW);
/*
* ... there must not be another ON SELECT rule already ...
*/
if (!replace && event_relation->rd_rules != NULL)
{
int i;
for (i = 0; i < event_relation->rd_rules->numLocks; i++)
{
RewriteRule *rule;
rule = event_relation->rd_rules->rules[i];
if (rule->event == CMD_SELECT)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("\"%s\" is already a view",
RelationGetRelationName(event_relation))));
}
}
/*
* ... and finally the rule must be named _RETURN.
*/
if (strcmp(rulename, ViewSelectRuleName) != 0)
{
/*
* In versions before 7.3, the expected name was _RETviewname. For
* backwards compatibility with old pg_dump output, accept that
* and silently change it to _RETURN. Since this is just a quick
* backwards-compatibility hack, limit the number of characters
* checked to a few less than NAMEDATALEN; this saves having to
* worry about where a multibyte character might have gotten
* truncated.
*/
if (strncmp(rulename, "_RET", 4) != 0 ||
strncmp(rulename + 4, RelationGetRelationName(event_relation),
NAMEDATALEN - 4 - 4) != 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("view rule for \"%s\" must be named \"%s\"",
RelationGetRelationName(event_relation),
ViewSelectRuleName)));
rulename = pstrdup(ViewSelectRuleName);
}
/*
* Are we converting a relation to a view?
*
* If so, check that the relation is empty because the storage for the
* relation is going to be deleted. Also insist that the rel not be
* involved in partitioning, nor have any triggers, indexes, child or
* parent tables, RLS policies, or RLS enabled. (Note: some of these
* tests are too strict, because they will reject relations that once
* had such but don't anymore. But we don't really care, because this
* whole business of converting relations to views is just an obsolete
* kluge to allow dump/reload of views that participate in circular
* dependencies.)
*/
if (event_relation->rd_rel->relkind != RELKIND_VIEW &&
event_relation->rd_rel->relkind != RELKIND_MATVIEW)
{
TableScanDesc scanDesc;
Snapshot snapshot;
TupleTableSlot *slot;
if (event_relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot convert partitioned table \"%s\" to a view",
RelationGetRelationName(event_relation))));
/* only case left: */
Assert(event_relation->rd_rel->relkind == RELKIND_RELATION);
if (event_relation->rd_rel->relispartition)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot convert partition \"%s\" to a view",
RelationGetRelationName(event_relation))));
snapshot = RegisterSnapshot(GetLatestSnapshot());
scanDesc = table_beginscan(event_relation, snapshot, 0, NULL);
slot = table_slot_create(event_relation, NULL);
if (table_scan_getnextslot(scanDesc, ForwardScanDirection, slot))
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("could not convert table \"%s\" to a view because it is not empty",
RelationGetRelationName(event_relation))));
ExecDropSingleTupleTableSlot(slot);
table_endscan(scanDesc);
UnregisterSnapshot(snapshot);
if (event_relation->rd_rel->relhastriggers)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("could not convert table \"%s\" to a view because it has triggers",
RelationGetRelationName(event_relation)),
errhint("In particular, the table cannot be involved in any foreign key relationships.")));
if (event_relation->rd_rel->relhasindex)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("could not convert table \"%s\" to a view because it has indexes",
RelationGetRelationName(event_relation))));
if (event_relation->rd_rel->relhassubclass)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("could not convert table \"%s\" to a view because it has child tables",
RelationGetRelationName(event_relation))));
if (has_superclass(RelationGetRelid(event_relation)))
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("could not convert table \"%s\" to a view because it has parent tables",
RelationGetRelationName(event_relation))));
if (event_relation->rd_rel->relrowsecurity)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("could not convert table \"%s\" to a view because it has row security enabled",
RelationGetRelationName(event_relation))));
if (relation_has_policies(event_relation))
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("could not convert table \"%s\" to a view because it has row security policies",
RelationGetRelationName(event_relation))));
RelisBecomingView = true;
}
}
else
{
/*
* For non-SELECT rules, a RETURNING list can appear in at most one of
* the actions ... and there can't be any RETURNING list at all in a
* conditional or non-INSTEAD rule. (Actually, there can be at most
* one RETURNING list across all rules on the same event, but it seems
* best to enforce that at rule expansion time.) If there is a
* RETURNING list, it must match the event relation.
*/
bool haveReturning = false;
foreach(l, action)
{
query = lfirst_node(Query, l);
if (!query->returningList)
continue;
if (haveReturning)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot have multiple RETURNING lists in a rule")));
haveReturning = true;
if (event_qual != NULL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("RETURNING lists are not supported in conditional rules")));
if (!is_instead)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("RETURNING lists are not supported in non-INSTEAD rules")));
checkRuleResultList(query->returningList,
RelationGetDescr(event_relation),
false, false);
}
/*
* And finally, if it's not an ON SELECT rule then it must *not* be
* named _RETURN. This prevents accidentally or maliciously replacing
* a view's ON SELECT rule with some other kind of rule.
*/
if (strcmp(rulename, ViewSelectRuleName) == 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("non-view rule for \"%s\" must not be named \"%s\"",
RelationGetRelationName(event_relation),
ViewSelectRuleName)));
}
/*
* This rule is allowed - prepare to install it.
*/
/* discard rule if it's null action and not INSTEAD; it's a no-op */
if (action != NIL || is_instead)
{
ruleId = InsertRule(rulename,
event_type,
event_relid,
is_instead,
event_qual,
action,
replace);
/*
* Set pg_class 'relhasrules' field true for event relation.
*
* Important side effect: an SI notice is broadcast to force all
* backends (including me!) to update relcache entries with the new
* rule.
*/
SetRelationRuleStatus(event_relid, true);
}
/* ---------------------------------------------------------------------
* If the relation is becoming a view:
* - delete the associated storage files
* - get rid of any system attributes in pg_attribute; a view shouldn't
* have any of those
* - remove the toast table; there is no need for it anymore, and its
* presence would make vacuum slightly more complicated
* - set relkind to RELKIND_VIEW, and adjust other pg_class fields
* to be appropriate for a view
*
* NB: we had better have AccessExclusiveLock to do this ...
* ---------------------------------------------------------------------
*/
if (RelisBecomingView)
{
Relation relationRelation;
Oid toastrelid;
HeapTuple classTup;
Form_pg_class classForm;
relationRelation = table_open(RelationRelationId, RowExclusiveLock);
toastrelid = event_relation->rd_rel->reltoastrelid;
/* drop storage while table still looks like a table */
RelationDropStorage(event_relation);
DeleteSystemAttributeTuples(event_relid);
/*
* Drop the toast table if any. (This won't take care of updating the
* toast fields in the relation's own pg_class entry; we handle that
* below.)
*/
if (OidIsValid(toastrelid))
{
ObjectAddress toastobject;
/*
* Delete the dependency of the toast relation on the main
* relation so we can drop the former without dropping the latter.
*/
deleteDependencyRecordsFor(RelationRelationId, toastrelid,
false);
/* Make deletion of dependency record visible */
CommandCounterIncrement();
/* Now drop toast table, including its index */
toastobject.classId = RelationRelationId;
toastobject.objectId = toastrelid;
toastobject.objectSubId = 0;
performDeletion(&toastobject, DROP_RESTRICT,
PERFORM_DELETION_INTERNAL);
}
/*
* SetRelationRuleStatus may have updated the pg_class row, so we must
* advance the command counter before trying to update it again.
*/
CommandCounterIncrement();
/*
* Fix pg_class entry to look like a normal view's, including setting
* the correct relkind and removal of reltoastrelid of the toast table
* we potentially removed above.
*/
classTup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(event_relid));
if (!HeapTupleIsValid(classTup))
elog(ERROR, "cache lookup failed for relation %u", event_relid);
classForm = (Form_pg_class) GETSTRUCT(classTup);
classForm->relam = InvalidOid;
classForm->reltablespace = InvalidOid;
classForm->relpages = 0;
classForm->reltuples = 0;
classForm->relallvisible = 0;
classForm->reltoastrelid = InvalidOid;
classForm->relhasindex = false;
classForm->relkind = RELKIND_VIEW;
classForm->relfrozenxid = InvalidTransactionId;
classForm->relminmxid = InvalidMultiXactId;
classForm->relreplident = REPLICA_IDENTITY_NOTHING;
CatalogTupleUpdate(relationRelation, &classTup->t_self, classTup);
heap_freetuple(classTup);
table_close(relationRelation, RowExclusiveLock);
}
ObjectAddressSet(address, RewriteRelationId, ruleId);
/* Close rel, but keep lock till commit... */
table_close(event_relation, NoLock);
return address;
}
/*
* checkRuleResultList
* Verify that targetList produces output compatible with a tupledesc
*
* The targetList might be either a SELECT targetlist, or a RETURNING list;
* isSelect tells which. This is used for choosing error messages.
*
* A SELECT targetlist may optionally require that column names match.
*/
static void
checkRuleResultList(List *targetList, TupleDesc resultDesc, bool isSelect,
bool requireColumnNameMatch)
{
ListCell *tllist;
int i;
/* Only a SELECT may require a column name match. */
Assert(isSelect || !requireColumnNameMatch);
i = 0;
foreach(tllist, targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(tllist);
Oid tletypid;
int32 tletypmod;
Form_pg_attribute attr;
char *attname;
/* resjunk entries may be ignored */
if (tle->resjunk)
continue;
i++;
if (i > resultDesc->natts)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
isSelect ?
errmsg("SELECT rule's target list has too many entries") :
errmsg("RETURNING list has too many entries")));
attr = TupleDescAttr(resultDesc, i - 1);
attname = NameStr(attr->attname);
/*
* Disallow dropped columns in the relation. This is not really
* expected to happen when creating an ON SELECT rule. It'd be
* possible if someone tried to convert a relation with dropped
* columns to a view, but the only case we care about supporting
* table-to-view conversion for is pg_dump, and pg_dump won't do that.
*
* Unfortunately, the situation is also possible when adding a rule
* with RETURNING to a regular table, and rejecting that case is
* altogether more annoying. In principle we could support it by
* modifying the targetlist to include dummy NULL columns
* corresponding to the dropped columns in the tupdesc. However,
* places like ruleutils.c would have to be fixed to not process such
* entries, and that would take an uncertain and possibly rather large
* amount of work. (Note we could not dodge that by marking the dummy
* columns resjunk, since it's precisely the non-resjunk tlist columns
* that are expected to correspond to table columns.)
*/
if (attr->attisdropped)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
isSelect ?
errmsg("cannot convert relation containing dropped columns to view") :
errmsg("cannot create a RETURNING list for a relation containing dropped columns")));
/* Check name match if required; no need for two error texts here */
if (requireColumnNameMatch && strcmp(tle->resname, attname) != 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("SELECT rule's target entry %d has different column name from column \"%s\"",
i, attname),
errdetail("SELECT target entry is named \"%s\".",
tle->resname)));
/* Check type match. */
tletypid = exprType((Node *) tle->expr);
if (attr->atttypid != tletypid)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
isSelect ?
errmsg("SELECT rule's target entry %d has different type from column \"%s\"",
i, attname) :
errmsg("RETURNING list's entry %d has different type from column \"%s\"",
i, attname),
isSelect ?
errdetail("SELECT target entry has type %s, but column has type %s.",
format_type_be(tletypid),
format_type_be(attr->atttypid)) :
errdetail("RETURNING list entry has type %s, but column has type %s.",
format_type_be(tletypid),
format_type_be(attr->atttypid))));
/*
* Allow typmods to be different only if one of them is -1, ie,
* "unspecified". This is necessary for cases like "numeric", where
* the table will have a filled-in default length but the select
* rule's expression will probably have typmod = -1.
*/
tletypmod = exprTypmod((Node *) tle->expr);
if (attr->atttypmod != tletypmod &&
attr->atttypmod != -1 && tletypmod != -1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
isSelect ?
errmsg("SELECT rule's target entry %d has different size from column \"%s\"",
i, attname) :
errmsg("RETURNING list's entry %d has different size from column \"%s\"",
i, attname),
isSelect ?
errdetail("SELECT target entry has type %s, but column has type %s.",
format_type_with_typemod(tletypid, tletypmod),
format_type_with_typemod(attr->atttypid,
attr->atttypmod)) :
errdetail("RETURNING list entry has type %s, but column has type %s.",
format_type_with_typemod(tletypid, tletypmod),
format_type_with_typemod(attr->atttypid,
attr->atttypmod))));
}
if (i != resultDesc->natts)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
isSelect ?
errmsg("SELECT rule's target list has too few entries") :
errmsg("RETURNING list has too few entries")));
}
/*
* setRuleCheckAsUser
* Recursively scan a query or expression tree and set the checkAsUser
* field to the given userid in all rtable entries.
*
* Note: for a view (ON SELECT rule), the checkAsUser field of the OLD
* RTE entry will be overridden when the view rule is expanded, and the
* checkAsUser field of the NEW entry is irrelevant because that entry's
* requiredPerms bits will always be zero. However, for other types of rules
* it's important to set these fields to match the rule owner. So we just set
* them always.
*/
void
setRuleCheckAsUser(Node *node, Oid userid)
{
(void) setRuleCheckAsUser_walker(node, &userid);
}
static bool
setRuleCheckAsUser_walker(Node *node, Oid *context)
{
if (node == NULL)
return false;
if (IsA(node, Query))
{
setRuleCheckAsUser_Query((Query *) node, *context);
return false;
}
return expression_tree_walker(node, setRuleCheckAsUser_walker,
(void *) context);
}
static void
setRuleCheckAsUser_Query(Query *qry, Oid userid)
{
ListCell *l;
/* Set all the RTEs in this query node */
foreach(l, qry->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
if (rte->rtekind == RTE_SUBQUERY)
{
/* Recurse into subquery in FROM */
setRuleCheckAsUser_Query(rte->subquery, userid);
}
else
rte->checkAsUser = userid;
}
/* Recurse into subquery-in-WITH */
foreach(l, qry->cteList)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(l);
setRuleCheckAsUser_Query(castNode(Query, cte->ctequery), userid);
}
/* If there are sublinks, search for them and process their RTEs */
if (qry->hasSubLinks)
query_tree_walker(qry, setRuleCheckAsUser_walker, (void *) &userid,
QTW_IGNORE_RC_SUBQUERIES);
}
/*
* Change the firing semantics of an existing rule.
*/
void
EnableDisableRule(Relation rel, const char *rulename,
char fires_when)
{
Relation pg_rewrite_desc;
Oid owningRel = RelationGetRelid(rel);
Oid eventRelationOid;
HeapTuple ruletup;
Form_pg_rewrite ruleform;
bool changed = false;
/*
* Find the rule tuple to change.
*/
pg_rewrite_desc = table_open(RewriteRelationId, RowExclusiveLock);
ruletup = SearchSysCacheCopy2(RULERELNAME,
ObjectIdGetDatum(owningRel),
PointerGetDatum(rulename));
if (!HeapTupleIsValid(ruletup))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("rule \"%s\" for relation \"%s\" does not exist",
rulename, get_rel_name(owningRel))));
ruleform = (Form_pg_rewrite) GETSTRUCT(ruletup);
/*
* Verify that the user has appropriate permissions.
*/
eventRelationOid = ruleform->ev_class;
Assert(eventRelationOid == owningRel);
if (!pg_class_ownercheck(eventRelationOid, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(eventRelationOid)),
get_rel_name(eventRelationOid));
/*
* Change ev_enabled if it is different from the desired new state.
*/
if (DatumGetChar(ruleform->ev_enabled) !=
fires_when)
{
ruleform->ev_enabled = CharGetDatum(fires_when);
CatalogTupleUpdate(pg_rewrite_desc, &ruletup->t_self, ruletup);
changed = true;
}
InvokeObjectPostAlterHook(RewriteRelationId, ruleform->oid, 0);
heap_freetuple(ruletup);
table_close(pg_rewrite_desc, RowExclusiveLock);
/*
* If we changed anything, broadcast a SI inval message to force each
* backend (including our own!) to rebuild relation's relcache entry.
* Otherwise they will fail to apply the change promptly.
*/
if (changed)
CacheInvalidateRelcache(rel);
}
/*
* Perform permissions and integrity checks before acquiring a relation lock.
*/
static void
RangeVarCallbackForRenameRule(const RangeVar *rv, Oid relid, Oid oldrelid,
void *arg)
{
HeapTuple tuple;
Form_pg_class form;
tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
if (!HeapTupleIsValid(tuple))
return; /* concurrently dropped */
form = (Form_pg_class) GETSTRUCT(tuple);
/* only tables and views can have rules */
if (form->relkind != RELKIND_RELATION &&
form->relkind != RELKIND_VIEW &&
form->relkind != RELKIND_PARTITIONED_TABLE)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("\"%s\" is not a table or view", rv->relname)));
if (!allowSystemTableMods && IsSystemClass(relid, form))
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied: \"%s\" is a system catalog",
rv->relname)));
/* you must own the table to rename one of its rules */
if (!pg_class_ownercheck(relid, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, get_relkind_objtype(get_rel_relkind(relid)), rv->relname);
ReleaseSysCache(tuple);
}
/*
* Rename an existing rewrite rule.
*/
ObjectAddress
RenameRewriteRule(RangeVar *relation, const char *oldName,
const char *newName)
{
Oid relid;
Relation targetrel;
Relation pg_rewrite_desc;
HeapTuple ruletup;
Form_pg_rewrite ruleform;
Oid ruleOid;
ObjectAddress address;
/*
* Look up name, check permissions, and acquire lock (which we will NOT
* release until end of transaction).
*/
relid = RangeVarGetRelidExtended(relation, AccessExclusiveLock,
0,
RangeVarCallbackForRenameRule,
NULL);
/* Have lock already, so just need to build relcache entry. */
targetrel = relation_open(relid, NoLock);
/* Prepare to modify pg_rewrite */
pg_rewrite_desc = table_open(RewriteRelationId, RowExclusiveLock);
/* Fetch the rule's entry (it had better exist) */
ruletup = SearchSysCacheCopy2(RULERELNAME,
ObjectIdGetDatum(relid),
PointerGetDatum(oldName));
if (!HeapTupleIsValid(ruletup))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("rule \"%s\" for relation \"%s\" does not exist",
oldName, RelationGetRelationName(targetrel))));
ruleform = (Form_pg_rewrite) GETSTRUCT(ruletup);
ruleOid = ruleform->oid;
/* rule with the new name should not already exist */
if (IsDefinedRewriteRule(relid, newName))
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("rule \"%s\" for relation \"%s\" already exists",
newName, RelationGetRelationName(targetrel))));
/*
* We disallow renaming ON SELECT rules, because they should always be
* named "_RETURN".
*/
if (ruleform->ev_type == CMD_SELECT + '0')
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("renaming an ON SELECT rule is not allowed")));
/* OK, do the update */
namestrcpy(&(ruleform->rulename), newName);
CatalogTupleUpdate(pg_rewrite_desc, &ruletup->t_self, ruletup);
InvokeObjectPostAlterHook(RewriteRelationId, ruleOid, 0);
heap_freetuple(ruletup);
table_close(pg_rewrite_desc, RowExclusiveLock);
/*
* Invalidate relation's relcache entry so that other backends (and this
* one too!) are sent SI message to make them rebuild relcache entries.
* (Ideally this should happen automatically...)
*/
CacheInvalidateRelcache(targetrel);
ObjectAddressSet(address, RewriteRelationId, ruleOid);
/*
* Close rel, but keep exclusive lock!
*/
relation_close(targetrel, NoLock);
return address;
}
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