From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 12 Jun 2021 17:29:24 +0000 (-0400)
Subject: Ensure pg_filenode_relation(0, 0) returns NULL.
X-Git-Tag: REL_12_8~108
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7681b78fba106b43d9b10d22b52ba2d5cbfc1326;p=thirdparty%2Fpostgresql.git

Ensure pg_filenode_relation(0, 0) returns NULL.

Previously, a zero value for the relfilenode resulted in
a confusing error message about "unexpected duplicate".
This function returns NULL for other invalid relfilenode
values, so zero should be treated likewise.

It's been like this all along, so back-patch to all supported
branches.

Justin Pryzby

Discussion: https://postgr.es/m/20210612023324.GT16435@telsasoft.com
---

diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index a87e7214e9f..bdaa341be7b 100644
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -921,7 +921,11 @@ pg_filenode_relation(PG_FUNCTION_ARGS)
 {
 	Oid			reltablespace = PG_GETARG_OID(0);
 	Oid			relfilenode = PG_GETARG_OID(1);
-	Oid			heaprel = InvalidOid;
+	Oid			heaprel;
+
+	/* test needed so RelidByRelfilenode doesn't misbehave */
+	if (!OidIsValid(relfilenode))
+		PG_RETURN_NULL();
 
 	heaprel = RelidByRelfilenode(reltablespace, relfilenode);