Pluggable storage backends: first steps

- add backend related columns in photo table
- add system resource storage class
- add code to load image data from backend class
- return "nosign" image as photo meta with SystemResource backend

config/dbstructure.config.php

@@ -34,7 +34,7 @@
 use Friendica\Database\DBA;
 
 if (!defined('DB_UPDATE_VERSION')) {
-	define('DB_UPDATE_VERSION', 1293);
+	define('DB_UPDATE_VERSION', 1294);
 }
 
 return [
@@ -955,6 +955,8 @@ return [
 			"allow_gid" => ["type" => "mediumtext", "comment" => "Access Control - list of allowed groups"],
 			"deny_cid" => ["type" => "mediumtext", "comment" => "Access Control - list of denied contact.id"],
 			"deny_gid" => ["type" => "mediumtext", "comment" => "Access Control - list of denied groups"],
+			"backend-class" => ["type" => "tinytext", "default" => "", "comment" => "Storage backend class"],
+			"backend-ref" => ["type" => "text", "default" => "", "comment" => "Storage backend data reference"]
 		],
 		"indexes" => [
 			"PRIMARY" => ["id"],

src/Model/Photo.php

@@ -58,7 +58,7 @@ class Photo extends BaseObject
 	public static function selectFirst(array $fields = [], array $condition = [], array $params = [])
 	{
 		if (empty($fields)) {
-			$selected = self::getFields();
+			$fields = self::getFields();
 		}
 
 		return DBA::selectFirst("photo", $fields, $condition, $params);
@@ -68,7 +68,7 @@ class Photo extends BaseObject
 	 * @brief Get a single photo given resource id and scale
 	 *
 	 * This method checks for permissions. Returns associative array
-	 * on success, a generic "red sign" data if user has no permission,
+	 * on success, "no sign" image info, if user has no permission,
 	 * false if photo does not exists
 	 *
 	 * @param string  $resourceid  Rescource ID for the photo
@@ -92,7 +92,7 @@ class Photo extends BaseObject
 
 		$photo = self::selectFirst([], $condition, $params);
 		if ($photo === false) {
-			return false; ///TODO: Return info for red sign image
+			return self::createPhotoForSystemResource("images/nosign.jpg");
 		}
 		return $photo;
 	}
@@ -116,13 +116,26 @@ class Photo extends BaseObject
 	 *
 	 * @return \Friendica\Object\Image
 	 */
-	public static function getImageForPhotoId($id)
+	public static function getImageForPhoto($photo)
 	{
-		$i = self::selectFirst(["data", "type"],["id"=>$id]);
+		$data = "";
-		if ($i===false) {
+		if ($photo["backend-class"] == "") {
+			// legacy data storage in "data" column
+			$i = self::selectFirst(["data"], ["id"=>$photo["id"]]);
+			if ($i===false) {
+				return null;
+			}
+			$data = $i["data"];
+		} else {
+			$backendClass = $photo["backend-class"];
+			$backendRef = $photo["backend-ref"];
+			$data = $backendClass::get($backendRef);
+		}
+
+		if ($data === "") {
 			return null;
 		}
-		return new Image($i["data"], $i["type"]);
+		return new Image($data, $photo["type"]);
 	}
 
 	/**
@@ -138,6 +151,25 @@ class Photo extends BaseObject
 		return $fields;
 	}
 
+	/**
+	 * @brief Construct a photo array for a system resource image
+	 *
+	 * @param string  $filename  Image file name relative to code root
+	 * @param string  $mimetype  Image mime type. Defaults to "image/jpeg"
+	 *
+	 * @return array
+	 */
+	public static function createPhotoForSystemResource($filename, $mimetype = "image/jpeg")
+	{
+		$fields = self::getFields();
+		$values = array_fill(0, count($fields), "");
+		$photo = array_combine($fields, $values);
+		$photo["backend-class"] = "\Friendica\Model\Storage\SystemResource";
+		$photo["backend-ref"] = $filename;
+		$photo["type"] = $mimetype;
+		$photo['cacheable'] = false;
+		return $photo;
+	}
 
 
 	/**

src/Model/Storage/SystemResource.php

@@ -0,0 +1,39 @@
+<?php
+/**
+ * @file src/Model/Storage/SystemStorage.php
+ */
+
+namespace Friendica\Model\Storage;
+
+/**
+ * @brief System resource storage class
+ *
+ * This class is used to load system resources, like images.
+ * Is not itended to be selectable by admins as default storage class.
+ */
+class SystemResource
+{
+	// Valid folders to look for resources
+	const VALID_FOLDERS = [ "images" ];
+
+	/**
+	 * @brief get data
+	 *
+	 * @param string  $resourceid
+	 *
+	 * @return string
+	 */
+	static function get($filename)
+	{
+		$folder = dirname($filename);
+		if (!in_array($folder, self::VALID_FOLDERS)) return "";
+		if (!file_exists($filename)) return "";
+		return file_get_contents($filename);
+	}
+
+	static function put($filename, $data)
+	{
+		throw new \BadMethodCallException();
+	}
+}
+

src/Module/Photo.php

@@ -77,9 +77,9 @@ class Photo extends BaseModule
 			killme();
 		}
 
-		$cacheable = ($photo["allow_cid"].$photo["allow_gid"].$photo["deny_cid"].$photo["deny_gid"] === "") || defaults($photo, "cacheable", false);
+		$cacheable = ($photo["allow_cid"].$photo["allow_gid"].$photo["deny_cid"].$photo["deny_gid"] === "") && (isset($photo["cacheable"])?$photo["cacheable"]:true);
 
-		$img = MPhoto::getImageForPhotoId($photo["id"]);
+		$img = MPhoto::getImageForPhoto($photo);
 
 		if (is_null($img) || !$img->isValid()) {
 			Logger::log("Invalid photo with id {$photo['id']}.");