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Disallow renaming a rule to "_RETURN".

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ON SELECT rules must be named "_RETURN", while other kinds of rules
must not be; this ancient restriction is depended on by various client
code.  We successfully enforced this convention in most places, but
ALTER RULE allowed renaming a non-SELECT rule to "_RETURN".  Notably,
that would break dump/restore, since the eventual CREATE RULE command
would reject the name.

While at it, remove DefineQueryRewrite's hack to substitute "_RETURN"
for the convention that was used before 7.3.  We dropped other
server-side code that supported restoring pre-7.3 dumps some time ago
(notably in e58a59975 and nearby commits), but this bit was missed.

Bug: #19543
Reported-by: Adam Pickering <adamkpickering@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/19543-461228e77f3b32fc@postgresql.org
Backpatch-through: 14
This commit is contained in:
Tom Lane 2026-07-04 11:34:26 -04:00
parent e0ff7fd9aa
commit a8c2547eaa
3 changed files with 19 additions and 20 deletions
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36
src/backend/rewrite/rewriteDefine.c
View file

@ -402,26 +402,11 @@ DefineQueryRewrite(const char *rulename,
* ... 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);
}
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("view rule for \"%s\" must be named \"%s\"",
RelationGetRelationName(event_relation),
ViewSelectRuleName)));
}
else
{
@ -867,6 +852,17 @@ RenameRewriteRule(RangeVar *relation, const char *oldName,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("renaming an ON SELECT rule is not allowed")));
/*
* Conversely, if it's not an ON SELECT rule then it must *not* be named
* _RETURN.
*/
if (strcmp(newName, ViewSelectRuleName) == 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("non-view rule for \"%s\" must not be named \"%s\"",
RelationGetRelationName(targetrel),
ViewSelectRuleName)));
/* OK, do the update */
namestrcpy(&(ruleform->rulename), newName);

2
src/test/regress/expected/rules.out
View file

@ -3436,6 +3436,8 @@ ALTER RULE NewInsertRule ON rule_v1 RENAME TO "_RETURN"; -- already exists
ERROR: rule "_RETURN" for relation "rule_v1" already exists
ALTER RULE "_RETURN" ON rule_v1 RENAME TO abc; -- ON SELECT rule cannot be renamed
ERROR: renaming an ON SELECT rule is not allowed
ALTER RULE rtest_t4_ins1 ON rtest_t4 RENAME TO "_RETURN"; -- also disallowed
ERROR: non-view rule for "rtest_t4" must not be named "_RETURN"
DROP VIEW rule_v1;
DROP TABLE rule_t1;
--

1
src/test/regress/sql/rules.sql
View file

@ -1087,6 +1087,7 @@ SELECT * FROM rule_v1;
ALTER RULE InsertRule ON rule_v1 RENAME TO NewInsertRule; -- doesn't exist
ALTER RULE NewInsertRule ON rule_v1 RENAME TO "_RETURN"; -- already exists
ALTER RULE "_RETURN" ON rule_v1 RENAME TO abc; -- ON SELECT rule cannot be renamed
ALTER RULE rtest_t4_ins1 ON rtest_t4 RENAME TO "_RETURN"; -- also disallowed
DROP VIEW rule_v1;
DROP TABLE rule_t1;