From 3f1814f36ed0dbaee0c12884cea1bf337c6a2b14 Mon Sep 17 00:00:00 2001
From: Brad Jorsch <bjorsch@wikimedia.org>
Date: Mon, 15 Dec 2014 11:04:57 -0500
Subject: [PATCH] API: Don't use an empty LinkBatch in ApiOpenSearch, part 2.

While Ie4609b08 took care of the empty $titles case, we get the same
problem if $titles is non-empty but contains only Special-namespace
titles.

Bug: T78074
Change-Id: Ic6572628e1da9953ef8212e49d4944e94d799f44
---
 includes/api/ApiOpenSearch.php | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/includes/api/ApiOpenSearch.php b/includes/api/ApiOpenSearch.php
index af09656814..5fc9f2b8a5 100644
--- a/includes/api/ApiOpenSearch.php
+++ b/includes/api/ApiOpenSearch.php
@@ -135,22 +135,24 @@ class ApiOpenSearch extends ApiBase {
 
 		if ( $resolveRedir ) {
 			// Query for redirects
-			$db = $this->getDb();
-			$lb = new LinkBatch( $titles );
-			$res = $db->select(
-				array( 'page', 'redirect' ),
-				array( 'page_namespace', 'page_title', 'rd_namespace', 'rd_title' ),
-				array(
-					'rd_from = page_id',
-					'rd_interwiki IS NULL OR rd_interwiki = ' . $db->addQuotes( '' ),
-					$lb->constructSet( 'page', $db ),
-				),
-				__METHOD__
-			);
 			$redirects = array();
-			foreach ( $res as $row ) {
-				$redirects[$row->page_namespace][$row->page_title] =
-					array( $row->rd_namespace, $row->rd_title );
+			$lb = new LinkBatch( $titles );
+			if ( !$lb->isEmpty() ) {
+				$db = $this->getDb();
+				$res = $db->select(
+					array( 'page', 'redirect' ),
+					array( 'page_namespace', 'page_title', 'rd_namespace', 'rd_title' ),
+					array(
+						'rd_from = page_id',
+						'rd_interwiki IS NULL OR rd_interwiki = ' . $db->addQuotes( '' ),
+						$lb->constructSet( 'page', $db ),
+					),
+					__METHOD__
+				);
+				foreach ( $res as $row ) {
+					$redirects[$row->page_namespace][$row->page_title] =
+						array( $row->rd_namespace, $row->rd_title );
+				}
 			}
 
 			// Bypass any redirects
-- 
2.20.1