Better handle when log_type isn't file and give explanation

Fixes nextcloud#52 (and possibly others)

Currently if `log_type` is set to anything other than `file` (the default) - such as syslog or systemd - the Logging page spins indefinitely. This fixes the backend assumptions about logging always being log_type `file` and also provides the admin (user) with an informative message so they know what's going on.

Signed-off-by: Josh Richards <[email protected]>

lib/Controller/LogController.php

@@ -56,8 +56,30 @@ public function __construct($appName,
 	 * @return TemplateResponse
 	 */
 	public function get($count = 50, $offset = 0, $levels = '11111') {
-		$iterator = $this->logIteratorFactory->getLogIterator($levels);
-		return $this->responseFromIterator($iterator, $count, $offset);
+		$logType = $this->config->getSystemValue('log_type','file');
+		if ($logType === 'file') { // we only support web access when `log_type` is set to `file` (the default)
+			$iterator = $this->logIteratorFactory->getLogIterator($levels);
+			return $this->responseFromIterator($iterator, $count, $offset);
+		} else { // A log_type other than `file` seems to be configured so:
+			 //     * Generate a dummy entry so we don't error out
+ 			 //     * Use the dummy entry to inform the admin to look elsewhere and/or correct their configuration
+			$dummyLine["id"] = uniqid();
+			$dummyLine["reqid"] = "00000000000000000000"; // irrelevant
+			$dummyLine["level"] = 1; // INFO
+			$dummyLine["time"] = date(DATE_ATOM, time());
+			$dummyLine["remoteAddr"] = "0.0.0.0";
+			$dummyLine["user"] = "---";
+			$dummyLine["app"] = "Logreader";
+			$dummyLine["method"] = "---";
+			$dummyLine["url"] = "---";
+			$dummyLine["message"] =
+				'File-based logging must be enabled to access logs from the Web UI. Your `log_type` is currently '
+				. 'set to: [' . $logType . ']. If you feel this is an error, please verify `log_type` in your '
+				. 'config.php and check the Nextcloud Administration Manual. This is not an actual log entry.';
+			$dummyLine["userAgent"] = "---";
+			$dummyLine["version"] = "---";
+			return new JSONResponse(['data' => $dummyLine, 'remain' => false]);
+		}
 	}
 
 
@@ -91,6 +113,12 @@ public function poll(string $lastReqId, string $levels = '11111'): JSONResponse
 		$cycles = 0;
 		$maxCycles = 20;
 
+		$logType = $this->config->getSystemValue('log_type','file');
+		if ($logType !== 'file') { // we only support access when `log_type` is set to `file` (the default)
+			// TODO: Don't even attempt polling in the front-end
+			sleep(20);
+			return new JSONResponse([]);
+		}
 		$lastItem = $this->getLastItem($levels);
 		while ($lastItem === null || $lastItem['reqId'] === $lastReqId) {
 			sleep(1);