From 8a096e9bf7154df9393f6920579996d7dfe8958e Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Fri, 10 Oct 2025 09:37:51 -0500
Subject: [PATCH v5 4/4] avoid locking before privilege checks in dblink

---
 contrib/dblink/dblink.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index 0cf4c27f2e9..1e7696beb50 100644
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -2460,6 +2460,21 @@ get_tuple_of_interest(Relation rel, int *pkattnums, int pknumatts, char **src_pk
 	return NULL;
 }
 
+static void
+RangeVarCallbackForDblink(const RangeVar *relation,
+						  Oid relId, Oid oldRelId, void *arg)
+{
+	AclResult	aclresult;
+
+	if (!OidIsValid(relId))
+		return;
+
+	aclresult = pg_class_aclcheck(relId, GetUserId(), *((AclMode *) arg));
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, get_relkind_objtype(get_rel_relkind(relId)),
+					   relation->relname);
+}
+
 /*
  * Open the relation named by relname_text, acquire specified type of lock,
  * verify we have specified permissions.
@@ -2469,19 +2484,13 @@ static Relation
 get_rel_from_relname(text *relname_text, LOCKMODE lockmode, AclMode aclmode)
 {
 	RangeVar   *relvar;
-	Relation	rel;
-	AclResult	aclresult;
+	Oid			relid;
 
 	relvar = makeRangeVarFromNameList(textToQualifiedNameList(relname_text));
-	rel = table_openrv(relvar, lockmode);
-
-	aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
-								  aclmode);
-	if (aclresult != ACLCHECK_OK)
-		aclcheck_error(aclresult, get_relkind_objtype(rel->rd_rel->relkind),
-					   RelationGetRelationName(rel));
+	relid = RangeVarGetRelidExtended(relvar, lockmode, 0,
+									 RangeVarCallbackForDblink, &aclmode);
 
-	return rel;
+	return table_open(relid, NoLock);
 }
 
 /*
-- 
2.39.5 (Apple Git-154)