From c78a4ae0748c27e3041e996d1637e3e0fc8ccaee Mon Sep 17 00:00:00 2001
From: Josh <josh.t.richards@gmail.com>
Date: Tue, 28 Oct 2025 14:07:19 -0400
Subject: [PATCH 1/2] fix(preview/bundled): copy content not resource id and
 improve error handling

Signed-off-by: Josh <josh.t.richards@gmail.com>
---
 lib/private/Preview/Bundled.php | 69 ++++++++++++++++++++++++++++++---
 1 file changed, 63 insertions(+), 6 deletions(-)

diff --git a/lib/private/Preview/Bundled.php b/lib/private/Preview/Bundled.php
index 6100e8262a4ba..cf241d22075c6 100644
--- a/lib/private/Preview/Bundled.php
+++ b/lib/private/Preview/Bundled.php
@@ -8,28 +8,73 @@
 
 use OC\Archive\ZIP;
 use OCP\Files\File;
+use OCP\IConfig;
 use OCP\IImage;
+use OCP\ITempManager;
+use OCP\Server;
+use Psr\Log\LoggerInterface;
 
 /**
  * Extracts a preview from files that embed them in an ZIP archive
  */
 abstract class Bundled extends ProviderV2 {
 	protected function extractThumbnail(File $file, string $path): ?IImage {
-		if ($file->getSize() === 0) {
+		$previewMaxFilesize = Server::get(IConfig::class)->getSystemValueInt('preview_max_filesize_image', 50);
+		$size = $file->getSize();
+		if ($size === 0) {
+			return null;
+		}
+		if ($previewMaxFilesize !== -1 && $size > ($previewMaxFilesize * 1024 * 1024)) {
 			return null;
 		}
 
-		$sourceTmp = \OC::$server->getTempManager()->getTemporaryFile();
-		$targetTmp = \OC::$server->getTempManager()->getTemporaryFile();
+		$sourceTmp = Server::get(ITempManager::class)->getTemporaryFile();
+		$targetTmp = Server::get(ITempManager::class)->getTemporaryFile();
 		$this->tmpFiles[] = $sourceTmp;
 		$this->tmpFiles[] = $targetTmp;
 
 		try {
-			$content = $file->fopen('r');
-			file_put_contents($sourceTmp, $content);
+			$src = $file->fopen('r');
+			if ($src === false) {
+				Server::get(LoggerInterface::class)->debug(
+					'Unable to extract thumbnail - fopen source failed',
+					['path' => $path]
+				);
+				return null;
+			}
+			
+			$dst = fopen($sourceTmp, 'wb');
+			if ($dst === false) {
+				Server::get(LoggerInterface::class)->debug(
+					'Unable to extract thumbnail - fopen destination failed',
+					['path' => $path]
+				);
+				return null;
+			}
+			
+			$bytes = stream_copy_to_stream($src, $dst);
+			if ($bytes === false || $bytes === 0) {
+				Server::get(LoggerInterface::class)->debug(
+					'Unable to extract thumbnail - copy returned 0 bytes',
+					['path' => $path]
+				);
+				return null;
+			}
+
+			fclose($dst);
+			$dst = null;
+			fclose($src);
+			$src = null;
 
 			$zip = new ZIP($sourceTmp);
-			$zip->extractFile($path, $targetTmp);
+			$result = $zip->extractFile($path, $targetTmp);
+			if ($result === false || !file_exists($targetTmp) || filesize($targetTmp) === 0) {
+				Server::get(LoggerInterface::class)->debug(
+					'Unable to extract thumbnail - extractFile failed or target missing/empty',
+					['path' => $path]
+				);
+				return null;
+			}
 
 			$image = new \OCP\Image();
 			$image->loadFromFile($targetTmp);
@@ -37,7 +82,19 @@ protected function extractThumbnail(File $file, string $path): ?IImage {
 
 			return $image;
 		} catch (\Throwable $e) {
+				Server::get(LoggerInterface::class)->debug(
+					'Unable to extract thumbnail - exception while extracting',
+					['message' => $e->getMessage(), 'path' => $path]
+				);
 			return null;
+		} finally {
+			if (isset($dst) && is_resource($dst)) {
+				fclose($dst);
+			}
+			if (isset($src) && is_resource($src)) {
+				fclose($src);
+			}
+			$this->cleanTmpFiles();
 		}
 	}
 }

From d73a1cc7471d1cfbec73857e33b56d1f0b494c06 Mon Sep 17 00:00:00 2001
From: Josh <josh.t.richards@gmail.com>
Date: Tue, 28 Oct 2025 14:25:08 -0400
Subject: [PATCH 2/2] fix: lint and psalm

Signed-off-by: Josh <josh.t.richards@gmail.com>
---
 lib/private/Preview/Bundled.php | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/lib/private/Preview/Bundled.php b/lib/private/Preview/Bundled.php
index cf241d22075c6..277962d49f24d 100644
--- a/lib/private/Preview/Bundled.php
+++ b/lib/private/Preview/Bundled.php
@@ -34,6 +34,7 @@ protected function extractThumbnail(File $file, string $path): ?IImage {
 		$this->tmpFiles[] = $targetTmp;
 
 		try {
+			/** @var resource|false|null */
 			$src = $file->fopen('r');
 			if ($src === false) {
 				Server::get(LoggerInterface::class)->debug(
@@ -42,7 +43,8 @@ protected function extractThumbnail(File $file, string $path): ?IImage {
 				);
 				return null;
 			}
-			
+
+			/** @var resource|false|null */
 			$dst = fopen($sourceTmp, 'wb');
 			if ($dst === false) {
 				Server::get(LoggerInterface::class)->debug(
@@ -51,7 +53,7 @@ protected function extractThumbnail(File $file, string $path): ?IImage {
 				);
 				return null;
 			}
-			
+
 			$bytes = stream_copy_to_stream($src, $dst);
 			if ($bytes === false || $bytes === 0) {
 				Server::get(LoggerInterface::class)->debug(
@@ -82,10 +84,10 @@ protected function extractThumbnail(File $file, string $path): ?IImage {
 
 			return $image;
 		} catch (\Throwable $e) {
-				Server::get(LoggerInterface::class)->debug(
-					'Unable to extract thumbnail - exception while extracting',
-					['message' => $e->getMessage(), 'path' => $path]
-				);
+			Server::get(LoggerInterface::class)->debug(
+				'Unable to extract thumbnail - exception while extracting',
+				['message' => $e->getMessage(), 'path' => $path]
+			);
 			return null;
 		} finally {
 			if (isset($dst) && is_resource($dst)) {