/*------------------------------------------------------------------------- * * rewriteDefine.c * routines for defining a rewrite rule * * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.72 2002/05/21 22:05:55 tgl Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/heapam.h" #include "catalog/catname.h" #include "catalog/indexing.h" #include "catalog/pg_rewrite.h" #include "commands/view.h" #include "miscadmin.h" #include "optimizer/clauses.h" #include "parser/parse_relation.h" #include "rewrite/rewriteDefine.h" #include "rewrite/rewriteManip.h" #include "rewrite/rewriteSupport.h" #include "storage/smgr.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/syscache.h" static void setRuleCheckAsUser(Query *qry, Oid userid); static bool setRuleCheckAsUser_walker(Node *node, Oid *context); /* * InsertRule - * takes the arguments and inserts them as a row into the system * relation "pg_rewrite" */ static Oid InsertRule(char *rulname, int evtype, Oid eventrel_oid, AttrNumber evslot_index, bool evinstead, char *evqual, char *actiontree) { int i; Datum values[Natts_pg_rewrite]; char nulls[Natts_pg_rewrite]; NameData rname; Relation pg_rewrite_desc; TupleDesc tupDesc; HeapTuple tup; Oid rewriteObjectId; if (IsDefinedRewriteRule(eventrel_oid, rulname)) elog(ERROR, "Attempt to insert rule \"%s\" failed: already exists", rulname); /* * Set up *nulls and *values arrays */ MemSet(nulls, ' ', sizeof(nulls)); i = 0; namestrcpy(&rname, rulname); values[i++] = NameGetDatum(&rname); /* rulename */ values[i++] = ObjectIdGetDatum(eventrel_oid); /* ev_class */ values[i++] = Int16GetDatum(evslot_index); /* ev_attr */ values[i++] = CharGetDatum(evtype + '0'); /* ev_type */ values[i++] = BoolGetDatum(evinstead); /* is_instead */ values[i++] = DirectFunctionCall1(textin, CStringGetDatum(evqual)); /* ev_qual */ values[i++] = DirectFunctionCall1(textin, CStringGetDatum(actiontree)); /* ev_action */ /* * create a new pg_rewrite tuple */ pg_rewrite_desc = heap_openr(RewriteRelationName, RowExclusiveLock); tupDesc = pg_rewrite_desc->rd_att; tup = heap_formtuple(tupDesc, values, nulls); rewriteObjectId = simple_heap_insert(pg_rewrite_desc, tup); if (RelationGetForm(pg_rewrite_desc)->relhasindex) { Relation idescs[Num_pg_rewrite_indices]; CatalogOpenIndices(Num_pg_rewrite_indices, Name_pg_rewrite_indices, idescs); CatalogIndexInsert(idescs, Num_pg_rewrite_indices, pg_rewrite_desc, tup); CatalogCloseIndices(Num_pg_rewrite_indices, idescs); } heap_freetuple(tup); heap_close(pg_rewrite_desc, RowExclusiveLock); return rewriteObjectId; } void DefineQueryRewrite(RuleStmt *stmt) { RangeVar *event_obj = stmt->relation; Node *event_qual = stmt->whereClause; CmdType event_type = stmt->event; bool is_instead = stmt->instead; List *action = stmt->actions; Relation event_relation; Oid ev_relid; Oid ruleId; int event_attno; Oid event_attype; char *actionP, *event_qualP; List *l; Query *query; AclResult aclresult; bool RelisBecomingView = false; /* * 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 might be * sufficient to grab ShareLock to lock out insert/update/delete * actions. But for now, let's just grab AccessExclusiveLock all the * time. */ event_relation = heap_openrv(event_obj, AccessExclusiveLock); ev_relid = RelationGetRelid(event_relation); /* * Check user has permission to apply rules to this relation. */ aclresult = pg_class_aclcheck(ev_relid, GetUserId(), ACL_RULE); if (aclresult != ACLCHECK_OK) aclcheck_error(aclresult, RelationGetRelationName(event_relation)); /* * No rule actions that modify OLD or NEW */ foreach(l, action) { query = (Query *) lfirst(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) elog(ERROR, "rule actions on OLD currently not supported" "\n\tuse views or triggers instead"); if (query->resultRelation == PRS2_NEW_VARNO) elog(ERROR, "rule actions on NEW currently not supported" "\n\tuse triggers instead"); } /* * Rules ON SELECT are restricted to view definitions */ if (event_type == CMD_SELECT) { List *tllist; int i; /* * So there cannot be INSTEAD NOTHING, ... */ if (length(action) == 0) { elog(ERROR, "instead nothing rules on select currently not supported" "\n\tuse views instead"); } /* * ... there cannot be multiple actions, ... */ if (length(action) > 1) elog(ERROR, "multiple action rules on select currently not supported"); /* * ... the one action must be a SELECT, ... */ query = (Query *) lfirst(action); if (!is_instead || query->commandType != CMD_SELECT) elog(ERROR, "only instead-select rules currently supported on select"); /* * ... there can be no rule qual, ... */ if (event_qual != NULL) elog(ERROR, "event qualifications not supported for rules on select"); /* * ... the targetlist of the SELECT action must exactly match the * event relation, ... */ i = 0; foreach(tllist, query->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(tllist); Resdom *resdom = tle->resdom; Form_pg_attribute attr; char *attname; if (resdom->resjunk) continue; i++; if (i > event_relation->rd_att->natts) elog(ERROR, "select rule's target list has too many entries"); attr = event_relation->rd_att->attrs[i - 1]; attname = NameStr(attr->attname); if (strcmp(resdom->resname, attname) != 0) elog(ERROR, "select rule's target entry %d has different column name from %s", i, attname); if (attr->atttypid != resdom->restype) elog(ERROR, "select rule's target entry %d has different type from attribute %s", i, attname); /* * 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. */ if (attr->atttypmod != resdom->restypmod && attr->atttypmod != -1 && resdom->restypmod != -1) elog(ERROR, "select rule's target entry %d has different size from attribute %s", i, attname); } if (i != event_relation->rd_att->natts) elog(ERROR, "select rule's target list has too few entries"); /* * ... there must not be another ON SELECT rule already ... */ if (event_relation->rd_rules != NULL) { for (i = 0; i < event_relation->rd_rules->numLocks; i++) { RewriteRule *rule; rule = event_relation->rd_rules->rules[i]; if (rule->event == CMD_SELECT) elog(ERROR, "\"%s\" is already a view", RelationGetRelationName(event_relation)); } } /* * ... and finally the rule must be named _RETURN. */ if (strcmp(stmt->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(stmt->rulename, "_RET", 4) != 0 || strncmp(stmt->rulename + 4, event_obj->relname, NAMEDATALEN - 4 - 4) != 0) elog(ERROR, "view rule for \"%s\" must be named \"%s\"", event_obj->relname, ViewSelectRuleName); stmt->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. */ if (event_relation->rd_rel->relkind != RELKIND_VIEW) { HeapScanDesc scanDesc; scanDesc = heap_beginscan(event_relation, SnapshotNow, 0, NULL); if (heap_getnext(scanDesc, ForwardScanDirection) != NULL) elog(ERROR, "Relation \"%s\" is not empty. Cannot convert it to view", event_obj->relname); heap_endscan(scanDesc); RelisBecomingView = true; } } /* * This rule is allowed - prepare to install it. */ event_attno = -1; event_attype = InvalidOid; /* * We want the rule's table references to be checked as though by the * rule owner, not the user referencing the rule. Therefore, scan * through the rule's rtables and set the checkAsUser field on all * rtable entries. */ foreach(l, action) { query = (Query *) lfirst(l); setRuleCheckAsUser(query, GetUserId()); } /* discard rule if it's null action and not INSTEAD; it's a no-op */ if (action != NIL || is_instead) { event_qualP = nodeToString(event_qual); actionP = nodeToString(action); ruleId = InsertRule(stmt->rulename, event_type, ev_relid, event_attno, is_instead, event_qualP, actionP); /* * Set pg_class 'relhasrules' field TRUE for event relation. If * appropriate, also modify the 'relkind' field to show that the * relation is now a view. * * Important side effect: an SI notice is broadcast to force all * backends (including me!) to update relcache entries with the * new rule. */ SetRelationRuleStatus(ev_relid, true, RelisBecomingView); } /* * IF the relation is becoming a view, delete the storage files * associated with it. NB: we had better have AccessExclusiveLock to * do this ... */ if (RelisBecomingView) smgrunlink(DEFAULT_SMGR, event_relation); /* Close rel, but keep lock till commit... */ heap_close(event_relation, NoLock); } /* * setRuleCheckAsUser * Recursively scan a query 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 * checkFor bits will never be set. However, for other types of rules it's * important to set these fields to match the rule owner. So we just set * them always. */ static void setRuleCheckAsUser(Query *qry, Oid userid) { List *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(rte->subquery, userid); } else rte->checkAsUser = userid; } /* If there are sublinks, search for them and process their RTEs */ if (qry->hasSubLinks) query_tree_walker(qry, setRuleCheckAsUser_walker, (void *) &userid, false /* already did the ones in rtable */ ); } /* * Expression-tree walker to find sublink queries */ static bool setRuleCheckAsUser_walker(Node *node, Oid *context) { if (node == NULL) return false; if (IsA(node, Query)) { Query *qry = (Query *) node; setRuleCheckAsUser(qry, *context); return false; } return expression_tree_walker(node, setRuleCheckAsUser_walker, (void *) context); } /* * Rename an existing rewrite rule. * * This is unused code at the moment. */ void RenameRewriteRule(Oid owningRel, const char *oldName, const char *newName) { Relation pg_rewrite_desc; HeapTuple ruletup; pg_rewrite_desc = heap_openr(RewriteRelationName, RowExclusiveLock); ruletup = SearchSysCacheCopy(RULERELNAME, ObjectIdGetDatum(owningRel), PointerGetDatum(oldName), 0, 0); if (!HeapTupleIsValid(ruletup)) elog(ERROR, "RenameRewriteRule: rule \"%s\" does not exist", oldName); /* should not already exist */ if (IsDefinedRewriteRule(owningRel, newName)) elog(ERROR, "Attempt to rename rule \"%s\" failed: \"%s\" already exists", oldName, newName); namestrcpy(&(((Form_pg_rewrite) GETSTRUCT(ruletup))->rulename), newName); simple_heap_update(pg_rewrite_desc, &ruletup->t_self, ruletup); /* keep system catalog indices current */ if (RelationGetForm(pg_rewrite_desc)->relhasindex) { Relation idescs[Num_pg_rewrite_indices]; CatalogOpenIndices(Num_pg_rewrite_indices, Name_pg_rewrite_indices, idescs); CatalogIndexInsert(idescs, Num_pg_rewrite_indices, pg_rewrite_desc, ruletup); CatalogCloseIndices(Num_pg_rewrite_indices, idescs); } heap_freetuple(ruletup); heap_close(pg_rewrite_desc, RowExclusiveLock); }