Fix multiple serialized values

src/Core/Config/Model/DatabaseConfig.php

@@ -61,15 +61,13 @@ class DatabaseConfig implements IManageConfigValues
 
 		foreach ($setCache->getAll() as $category => $data) {
 			foreach ($data as $key => $value) {
-				$this->cache->set($category, $key, $value, Cache::SOURCE_DATA);
-				$this->database->insert('config', ['cat' => $category, 'k' => $key, 'v' => serialize($value)], Database::INSERT_UPDATE);
+				$this->set($category, $key, $value);
 			}
 		}
 
 		foreach ($delCache->getAll() as $category => $keys) {
 			foreach ($keys as $key => $value) {
-				$this->cache->delete($category, $key);
-				$this->database->delete('config', ['cat' => $category, 'k' => $key]);
+				$this->delete($category, $key);
 			}
 		}
 
@@ -85,6 +83,10 @@ class DatabaseConfig implements IManageConfigValues
 	/** {@inheritDoc} */
 	public function set(string $cat, string $key, $value): bool
 	{
+		// In case someone or something already serialized a config entry, unserialize it first
+		// We serialize values just once
+		$value = SerializeUtil::maybeUnserialize($value);
+
 		$this->cache->set($cat, $key, $value, Cache::SOURCE_DATA);
 		return $this->database->insert('config', ['cat' => $cat, 'k' => $key, 'v' => serialize($value)], Database::INSERT_UPDATE);
 	}

src/Core/Config/Util/SerializeUtil.php

@@ -28,10 +28,24 @@ namespace Friendica\Core\Config\Util;
  */
 class SerializeUtil
 {
+	/**
+	 * Checks if the value needs to get unserialized and returns the unserialized value
+	 *
+	 * @param mixed $value A possible serialized value
+	 *
+	 * @return mixed The unserialized value
+	 */
 	public static function maybeUnserialize($value)
 	{
-		if (static::isSerialized($value)) {
-			return @unserialize(trim($value));
+		// This checks for possible multiple serialized values
+		while (SerializeUtil::isSerialized($value)) {
+			$oldValue = $value;
+			$value = @unserialize($value);
+
+			// If there's no change after the unserialize call, break the loop (avoid endless loops)
+			if ($oldValue === $value) {
+				break;
+			}
 		}
 
 		return $value;