Improve behavior of concurrent rename statements.

Previously, renaming a table, sequence, view, index, foreign table,
column, or trigger checked permissions before locking the object, which
meant that if permissions were revoked during the lock wait, we would
still allow the operation.  Similarly, if the original object is dropped
and a new one with the same name is created, the operation will be allowed
if we had permissions on the old object; the permissions on the new
object don't matter.  All this is now fixed.

Along the way, attempting to rename a trigger on a foreign table now gives
the same error message as trying to create one there in the first place
(i.e. that it's not a table or view) rather than simply stating that no
trigger by that name exists.

Patch by me; review by Noah Misch.

1 files changed, 9 insertions, 53 deletions

diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index f9be3a9a4ec..2954bb27dd9 100644
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -105,62 +105,18 @@ ExecRenameStmt(RenameStmt *stmt)
 		case OBJECT_SEQUENCE:
 		case OBJECT_VIEW:
 		case OBJECT_INDEX:
+		case OBJECT_FOREIGN_TABLE:
+			RenameRelation(stmt);
+			break;
+
 		case OBJECT_COLUMN:
 		case OBJECT_ATTRIBUTE:
+			renameatt(stmt);
+			break;
+
 		case OBJECT_TRIGGER:
-		case OBJECT_FOREIGN_TABLE:
-			{
-				Oid			relid;
-
-				CheckRelationOwnership(stmt->relation, true);
-
-				/*
-				 * Lock level used here should match what will be taken later,
-				 * in RenameRelation, renameatt, or renametrig.
-				 */
-				relid = RangeVarGetRelid(stmt->relation, AccessExclusiveLock,
-										 false);
-
-				switch (stmt->renameType)
-				{
-					case OBJECT_TABLE:
-					case OBJECT_SEQUENCE:
-					case OBJECT_VIEW:
-					case OBJECT_INDEX:
-					case OBJECT_FOREIGN_TABLE:
-						{
-							/*
-							 * RENAME TABLE requires that we (still) hold
-							 * CREATE rights on the containing namespace, as
-							 * well as ownership of the table.
-							 */
-							Oid			namespaceId = get_rel_namespace(relid);
-							AclResult	aclresult;
-
-							aclresult = pg_namespace_aclcheck(namespaceId,
-															  GetUserId(),
-															  ACL_CREATE);
-							if (aclresult != ACLCHECK_OK)
-								aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
-											get_namespace_name(namespaceId));
-
-							RenameRelation(relid, stmt->newname, stmt->renameType);
-							break;
-						}
-					case OBJECT_COLUMN:
-					case OBJECT_ATTRIBUTE:
-						renameatt(relid, stmt);
-						break;
-					case OBJECT_TRIGGER:
-						renametrig(relid,
-								   stmt->subname,		/* old att name */
-								   stmt->newname);		/* new att name */
-						break;
-					default:
-						 /* can't happen */ ;
-				}
-				break;
-			}
+			renametrig(stmt);
+			break;
 
 		case OBJECT_TSPARSER:
 			RenameTSParser(stmt->object, stmt->newname);