Add a helper function that makes it easier to log from anywhere

composer.json

@@ -11,6 +11,9 @@
 		}
 	},
 	"autoload": {
+		"files": [
+			"lib/public/Log/functions.php"
+		],
 		"psr-4": {
 			"": "lib/private/legacy",
 			"OC\\": "lib/private",

lib/composer/composer/autoload_files.php

@@ -0,0 +1,10 @@
+<?php
+
+// autoload_files.php @generated by Composer
+
+$vendorDir = dirname(__DIR__);
+$baseDir = dirname(dirname($vendorDir));
+
+return array(
+    '03ae51fe9694f2f597f918142c49ff7a' => $baseDir . '/lib/public/Log/functions.php',
+);

lib/composer/composer/autoload_real.php

@@ -31,6 +31,25 @@ public static function getLoader()
 
         $loader->register(true);
 
+        $includeFiles = \Composer\Autoload\ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2::$files;
+        foreach ($includeFiles as $fileIdentifier => $file) {
+            composerRequire749170dad3f5e7f9ca158f5a9f04f6a2($fileIdentifier, $file);
+        }
+
         return $loader;
     }
 }
+
+/**
+ * @param string $fileIdentifier
+ * @param string $file
+ * @return void
+ */
+function composerRequire749170dad3f5e7f9ca158f5a9f04f6a2($fileIdentifier, $file)
+{
+    if (empty($GLOBALS['__composer_autoload_files'][$fileIdentifier])) {
+        $GLOBALS['__composer_autoload_files'][$fileIdentifier] = true;
+
+        require $file;
+    }
+}

lib/composer/composer/autoload_static.php

@@ -6,6 +6,10 @@
 
 class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
 {
+    public static $files = array (
+        '03ae51fe9694f2f597f918142c49ff7a' => __DIR__ . '/../../..' . '/lib/public/Log/functions.php',
+    );
+
     public static $prefixLengthsPsr4 = array (
         'O' => 
         array (

lib/public/Log/functions.php

@@ -0,0 +1,73 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * @copyright 2022 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @author 2022 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace OCP\Log;
+
+use OC;
+use OCP\AppFramework\QueryException;
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
+use function class_exists;
+
+/**
+ * Get a PSR logger
+ *
+ * Whenever possible, inject a logger into your classes instead of relying on
+ * this helper function.
+ *
+ * @warning the returned logger implementation is not guaranteed to be the same
+ *          between two function calls. During early stages of the process you
+ *          might in fact get a noop implementation when Nextcloud isn't ready
+ *          to log. Therefore you MUST NOT cache the result of this function but
+ *          fetch a new logger for every log line you want to write.
+ *
+ * @param string|null $appId optional parameter to acquire the app-specific logger
+ *
+ * @return LoggerInterface
+ * @since 24.0.0
+ */
+function logger(string $appId = null): LoggerInterface {
+	if (!class_exists(OC::class) || OC::$server === null) {
+		// If someone calls this log before Nextcloud is initialized, there is
+		// no logging available. In that case we return a noop implementation
+		// TODO: evaluate whether logging to error_log could be an alternative
+		return new NullLogger();
+	}
+
+	if ($appId !== null) {
+		try {
+			$appContainer = OC::$server->getRegisteredAppContainer($appId);
+			return $appContainer->get(LoggerInterface::class);
+		} catch (QueryException $e) {
+			// Ignore and return the server logger below
+		}
+	}
+
+	try {
+		return OC::$server->get(LoggerInterface::class);
+	} catch (QueryException $e) {
+		return new NullLogger();
+	}
+}