make previews work for shared files in the versions drop-down

apps/files_versions/ajax/preview.php

@@ -6,31 +6,38 @@
  * See the COPYING-README file.
  */
 \OC_Util::checkLoggedIn();
-
+error_log("get preview!");
 if(!\OC_App::isEnabled('files_versions')){
 	exit;
 }
 
 $file = array_key_exists('file', $_GET) ? (string) urldecode($_GET['file']) : '';
+$user = array_key_exists('user', $_GET) ? $_GET['user'] : '';
 $maxX = array_key_exists('x', $_GET) ? (int) $_GET['x'] : 44;
 $maxY = array_key_exists('y', $_GET) ? (int) $_GET['y'] : 44;
 $version = array_key_exists('version', $_GET) ? $_GET['version'] : '';
 $scalingUp = array_key_exists('scalingup', $_GET) ? (bool) $_GET['scalingup'] : true;
 
+if($user === '') {
+	\OC_Response::setStatus(400); //400 Bad Request
+	\OC_Log::write('versions-preview', 'No user parameter was passed', \OC_Log::DEBUG);
+	exit;
+}
+
 if($file === '' && $version === '') {
 	\OC_Response::setStatus(400); //400 Bad Request
-	\OC_Log::write('core-preview', 'No file parameter was passed', \OC_Log::DEBUG);
+	\OC_Log::write('versions-preview', 'No file parameter was passed', \OC_Log::DEBUG);
 	exit;
 }
 
 if($maxX === 0 || $maxY === 0) {
 	\OC_Response::setStatus(400); //400 Bad Request
-	\OC_Log::write('core-preview', 'x and/or y set to 0', \OC_Log::DEBUG);
+	\OC_Log::write('versions-preview', 'x and/or y set to 0', \OC_Log::DEBUG);
 	exit;
 }
 
 try{
-	$preview = new \OC\Preview(\OC_User::getUser(), 'files_versions');
+	$preview = new \OC\Preview($user, 'files_versions');
 	$preview->setFile($file.'.v'.$version);
 	$preview->setMaxX($maxX);
 	$preview->setMaxY($maxY);

apps/files_versions/lib/versions.php

@@ -257,7 +257,7 @@ class Storage {
 					$versions[$key]['cur'] = 0;
 					$versions[$key]['version'] = $version;
 					$versions[$key]['humanReadableTimestamp'] = self::getHumanReadableTimestamp($version);
-					$versions[$key]['preview'] = \OCP\Util::linkToRoute('core_ajax_versions_preview', array('file' => $filename, 'version' => $version));
+					$versions[$key]['preview'] = \OCP\Util::linkToRoute('core_ajax_versions_preview', array('file' => $filename, 'version' => $version, 'user' => $uid));
 					$versions[$key]['path'] = $filename;
 					$versions[$key]['size'] = $file['size'];
 				}