Don't fill the pagination cache if there are no extra items

apps/dav/lib/Paginate/LimitedCopyIterator.php

@@ -20,6 +20,7 @@
 class LimitedCopyIterator extends \AppendIterator {
 	private array $skipped = [];
 	private array $copy = [];
+	private readonly bool $hasOthers;
 
 	public function __construct(\Traversable $iterator, int $count, int $offset = 0) {
 		parent::__construct();
@@ -29,17 +30,17 @@ public function __construct(\Traversable $iterator, int $count, int $offset = 0)
 		}
 		$iterator = new \NoRewindIterator($iterator);
 
-		$i = 0;
-		while ($iterator->valid() && ++$i <= $offset) {
-			$this->skipped[] = $iterator->current();
+		while ($iterator->valid() && count($this->skipped) < $offset) {
+			$this->skipped[$iterator->key()] = $iterator->current();
 			$iterator->next();
 		}
 
 		while ($iterator->valid() && count($this->copy) < $count) {
-			$this->copy[] = $iterator->current();
+			$this->copy[$iterator->key()] = $iterator->current();
 			$iterator->next();
 		}
 
+		$this->hasOthers = $iterator->valid() || count($this->skipped) > 0;
 		$this->append(new \ArrayIterator($this->skipped));
 		$this->append($this->getRequestedItems());
 		$this->append($iterator);
@@ -48,4 +49,11 @@ public function __construct(\Traversable $iterator, int $count, int $offset = 0)
 	public function getRequestedItems(): \Iterator {
 		return new \ArrayIterator($this->copy);
 	}
+
+	/**
+	 * Are there any other items in the iterator aside from the requested ones
+	 */
+	public function hasOthers(): bool {
+		return $this->hasOthers;
+	}
 }

apps/dav/lib/Paginate/PaginatePlugin.php

@@ -59,17 +59,21 @@ public function onMultiStatus(&$fileProperties): void {
 			$offset = (int)$request->getHeader(self::PAGINATE_OFFSET_HEADER);
 
 			$copyIterator = new LimitedCopyIterator($fileProperties, $pageSize, $offset);
-			// wrap the iterator with another that renders XML, this way we
-			// cache XML, but we keep the first $pageSize elements as objects
-			// to use for the response of the first page.
-			$rendererGenerator = $this->getXmlRendererGenerator($copyIterator);
-			['token' => $token, 'count' => $count] = $this->cache->store($url, $rendererGenerator);
+
+			if ($copyIterator->hasOthers()) {
+				// wrap the iterator with another that renders XML, this way we
+				// cache XML, but we keep the first $pageSize elements as objects
+				// to use for the response of the first page.
+				$rendererGenerator = $this->getXmlRendererGenerator($copyIterator);
+				['token' => $token, 'count' => $count] = $this->cache->store($url, $rendererGenerator);
+
+				$this->server->httpResponse->addHeader(self::PAGINATE_HEADER, 'true');
+				$this->server->httpResponse->addHeader(self::PAGINATE_TOKEN_HEADER, $token);
+				$this->server->httpResponse->addHeader(self::PAGINATE_TOTAL_HEADER, (string)$count);
+				$request->setHeader(self::PAGINATE_TOKEN_HEADER, $token);
+			}
 
 			$fileProperties = $copyIterator->getRequestedItems();
-			$this->server->httpResponse->addHeader(self::PAGINATE_HEADER, 'true');
-			$this->server->httpResponse->addHeader(self::PAGINATE_TOKEN_HEADER, $token);
-			$this->server->httpResponse->addHeader(self::PAGINATE_TOTAL_HEADER, (string)$count);
-			$request->setHeader(self::PAGINATE_TOKEN_HEADER, $token);
 		}
 	}
 

apps/dav/tests/unit/Paginate/LimitedCopyIteratorTest.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\DAV\Tests\unit\Paginate;
+
+use OCA\DAV\Paginate\LimitedCopyIterator;
+use Test\TestCase;
+
+class LimitedCopyIteratorTest extends TestCase {
+	public function testBasic() {
+		$data = [1, 2, 3, 4, 5, 6, 7];
+
+		$copy = new LimitedCopyIterator(new \ArrayIterator($data), 5, 0);
+		$this->assertEquals([1, 2, 3, 4, 5], iterator_to_array($copy->getRequestedItems()));
+		$this->assertTrue($copy->hasOthers());
+		$this->assertEquals($data, iterator_to_array($copy));
+
+		$copy = new LimitedCopyIterator(new \ArrayIterator($data), 15, 0);
+		$this->assertEquals([1, 2, 3, 4, 5, 6, 7], iterator_to_array($copy->getRequestedItems()));
+		$this->assertFalse($copy->hasOthers());
+		$this->assertEquals($data, iterator_to_array($copy));
+
+		$copy = new LimitedCopyIterator(new \ArrayIterator($data), 15, 1);
+		$this->assertEquals([1 => 2, 3, 4, 5, 6, 7], iterator_to_array($copy->getRequestedItems()));
+		$this->assertTrue($copy->hasOthers());
+		$this->assertEquals($data, iterator_to_array($copy));
+	}
+
+}