Stop writing data to the output buffer in case the connection is no l…

changelog/unreleased/37219

@@ -0,0 +1,11 @@
+Bugfix: Stop writing data to the output buffer when the connection is not alive
+
+Publicly shared video playback is sending a range http request to get the video
+content. In cases where the user is seeking to different positions of the video
+will result in a pretty high server load because all the video content is sent
+to the browser. Without detecting the connection state on server side all data
+is put to the output buffer.
+With this change the server processes will stop sending data as soon as the
+connection is detected as non-active.
+
+https://github.com/owncloud/core/pull/37219

lib/private/Files/View.php

@@ -475,6 +475,7 @@ public function readfile($path) {
 			$size = $this->filesize($path);
 			while (!\feof($handle)) {
 				echo \fread($handle, $chunkSize);
+				$this->checkConnectionStatus();
 				\flush();
 			}
 			return $size;
@@ -504,10 +505,10 @@ public function readfilePart($path, $from, $to) {
 						$len = $chunkSize;
 					}
 					echo \fread($handle, $len);
+					$this->checkConnectionStatus();
 					\flush();
 				}
-				$size = \ftell($handle) - $from;
-				return $size;
+				return \ftell($handle) - $from;
 			}
 
 			throw new \OCP\Files\UnseekableException('fseek error');
@@ -2268,4 +2269,11 @@ private function createParentDirectories($filePath) {
 	public static function setIgnorePartFile($isIgnored) {
 		self::$ignorePartFile = $isIgnored;
 	}
+
+	private function checkConnectionStatus(): void {
+		$connectionStatus = \connection_status();
+		if ($connectionStatus !== 0) {
+			throw new \RuntimeException("Connection lost. Status: $connectionStatus");
+		}
+	}
 }

lib/private/legacy/files.php

@@ -192,9 +192,6 @@ public static function get($dir, $files, $params = null) {
 			$l = \OC::$server->getL10N('lib');
 			/* @phan-suppress-next-line PhanUndeclaredMethod */
 			$hint = \method_exists($ex, 'getHint') ? $ex->getHint() : '';
-			if ($event->hasArgument('message')) {
-				$hint .= ' ' . $event->getArgument('message');
-			}
 			\OC_Template::printErrorPage($l->t('File cannot be downloaded'), $hint);
 		}
 	}