New core-extensions to allow Docker volumes for third-party extensions (#2837)

* New core-extensions to allow Docker volumes for third-party extensions

#Fix https://github.com/FreshRSS/FreshRSS/issues/2650
Split our extensions directory into two:
1) Core extensions shipped with FreshRSS in ./lib/core-extensions/
2) Third-party extensions modified by end-users in ./extensions/ which
can easily be mounted as a Docker volume

* Example of Docker Compose with extensions

* Back-compatibility + fix array merge bug

10 files changed, 43 insertions, 22 deletions

diff --git a/Docker/README.md b/Docker/README.md
index 6920471df..92f13bcf3 100644
--- a/Docker/README.md
+++ b/Docker/README.md
@@ -56,10 +56,12 @@ You must first chose a domain (DNS) or sub-domain, e.g. `freshrss.example.net`.
 
 ```sh
 docker volume create freshrss-data
+docker volume create freshrss-extensions
 
 # Remember to replace freshrss.example.net by your server address in the command below:
 docker run -d --restart unless-stopped --log-opt max-size=10m \
   -v freshrss-data:/var/www/FreshRSS/data \
+  -v freshrss-extensions:/var/www/FreshRSS/extensions \
   -e 'CRON_MIN=4,34' \
   -e TZ=Europe/Paris \
   --net freshrss-network \
@@ -223,6 +225,7 @@ See cron option 1 for customising the cron schedule.
 ```sh
 docker run -d --restart unless-stopped --log-opt max-size=10m \
   -v freshrss-data:/var/www/FreshRSS/data \
+  -v freshrss-extensions:/var/www/FreshRSS/extensions \
   -e 'CRON_MIN=17,47' \
   --net freshrss-network \
   --name freshrss_cron freshrss/freshrss \
@@ -233,6 +236,7 @@ docker run -d --restart unless-stopped --log-opt max-size=10m \
 ```sh
 docker run -d --restart unless-stopped --log-opt max-size=10m \
   -v freshrss-data:/var/www/FreshRSS/data \
+  -v freshrss-extensions:/var/www/FreshRSS/extensions \
   -e 'CRON_MIN=27,57' \
   --net freshrss-network \
   --name freshrss_cron freshrss/freshrss:alpine \
diff --git a/Docker/docker-compose.yml b/Docker/docker-compose.yml
index 1c0a79ab8..9b8952329 100644
--- a/Docker/docker-compose.yml
+++ b/Docker/docker-compose.yml
@@ -20,6 +20,7 @@ services:
       - freshrss_postgresql
     volumes:
       - freshrss_data:/var/www/FreshRSS/data
+      - freshrss_extensions:/var/www/FreshRSS/extensions
     environment:
       - CRON_MIN=*/20
       - TZ=Europe/Copenhagen
@@ -29,3 +30,4 @@ services:
 volumes:
   pgsql_data:
   freshrss_data:
+  freshrss_extensions:
diff --git a/constants.php b/constants.php
index 67e3d2677..65a297e85 100644
--- a/constants.php
+++ b/constants.php
@@ -13,7 +13,7 @@ define('INDEX_PATH', PUBLIC_PATH . PUBLIC_TO_INDEX_PATH);
 define('PUBLIC_RELATIVE', '..');
 define('LIB_PATH', FRESHRSS_PATH . '/lib');
 define('APP_PATH', FRESHRSS_PATH . '/app');
-define('EXTENSIONS_PATH', FRESHRSS_PATH . '/extensions');
+define('CORE_EXTENSIONS_PATH', LIB_PATH . '/core-extensions');
 //</Not customisable>
 
 function safe_define($name, $value) {
@@ -49,6 +49,11 @@ safe_define('API_LOG', USERS_PATH . '/_/log_api.txt');
 safe_define('CACHE_PATH', DATA_PATH . '/cache');
 safe_define('PSHB_LOG', USERS_PATH . '/_/log_pshb.txt');
 safe_define('PSHB_PATH', DATA_PATH . '/PubSubHubbub');
+safe_define('EXTENSIONS_DATA', DATA_PATH . '/extensions-data');
+safe_define('THIRDPARTY_EXTENSIONS_PATH', FRESHRSS_PATH . '/extensions');
+
+//Deprecated constants
+safe_define('EXTENSIONS_PATH', FRESHRSS_PATH . '/extensions');
 
 //Directory used for feed mutex with *.freshrss.lock files. Must be writable.
 safe_define('TMP_PATH', sys_get_temp_dir());
diff --git a/extensions/README.md b/extensions/README.md
index 62766d6f2..9833196b4 100644
--- a/extensions/README.md
+++ b/extensions/README.md
@@ -1,4 +1,4 @@
-# FreshRSS extensions
+# FreshRSS third-party extensions
 
 You may place custom extensions for FreshRSS in this directory.
 
diff --git a/lib/Minz/ExtensionManager.php b/lib/Minz/ExtensionManager.php
index e6b8dafb0..b2814e4a3 100644
--- a/lib/Minz/ExtensionManager.php
+++ b/lib/Minz/ExtensionManager.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * An extension manager to load extensions present in EXTENSIONS_PATH.
+ * An extension manager to load extensions present in CORE_EXTENSIONS_PATH and THIRDPARTY_EXTENSIONS_PATH.
  *
  * @todo see coding style for methods!!
  */
@@ -78,16 +78,17 @@ class Minz_ExtensionManager {
 	 * inherit from Minz_Extension class.
 	 */
 	public static function init() {
-		$list_potential_extensions = array_values(array_diff(
-			scandir(EXTENSIONS_PATH),
-			array('..', '.')
-		));
+		$list_core_extensions = array_diff(scandir(CORE_EXTENSIONS_PATH), [ '..', '.' ]);
+		$list_thirdparty_extensions = array_diff(scandir(THIRDPARTY_EXTENSIONS_PATH), [ '..', '.' ], $list_core_extensions);
+		array_walk($list_core_extensions, function (&$s) { $s = CORE_EXTENSIONS_PATH . '/' . $s; });
+		array_walk($list_thirdparty_extensions, function (&$s) { $s = THIRDPARTY_EXTENSIONS_PATH . '/' . $s; });
+
+		$list_potential_extensions = array_merge($list_core_extensions, $list_thirdparty_extensions);
 
 		$system_conf = Minz_Configuration::get('system');
 		self::$ext_auto_enabled = $system_conf->extensions_enabled;
 
-		foreach ($list_potential_extensions as $ext_dir) {
-			$ext_pathname = EXTENSIONS_PATH . '/' . $ext_dir;
+		foreach ($list_potential_extensions as $ext_pathname) {
 			if (!is_dir($ext_pathname)) {
 				continue;
 			}
@@ -111,7 +112,7 @@ class Minz_ExtensionManager {
 
 			// Try to load extension itself
 			$extension = self::load($meta_json);
-			if (!is_null($extension)) {
+			if ($extension != null) {
 				self::register($extension);
 			}
 		}
diff --git a/lib/core-extensions/README.md b/lib/core-extensions/README.md
new file mode 100644
index 000000000..7d48fbffd
--- /dev/null
+++ b/lib/core-extensions/README.md
@@ -0,0 +1,5 @@
+# FreshRSS core extensions
+
+This directory contains some core extensions shipped with FreshRSS.
+
+For custom third-party extensions, use the `./FreshRSS/extensions/` directory instead.
diff --git a/extensions/Tumblr-GDPR/README.md b/lib/core-extensions/Tumblr-GDPR/README.md
index fc5e4dd50..fc5e4dd50 100644
--- a/extensions/Tumblr-GDPR/README.md
+++ b/lib/core-extensions/Tumblr-GDPR/README.md
diff --git a/extensions/Tumblr-GDPR/extension.php b/lib/core-extensions/Tumblr-GDPR/extension.php
index 83bdf2189..83bdf2189 100644
--- a/extensions/Tumblr-GDPR/extension.php
+++ b/lib/core-extensions/Tumblr-GDPR/extension.php
diff --git a/extensions/Tumblr-GDPR/metadata.json b/lib/core-extensions/Tumblr-GDPR/metadata.json
index b5c33787b..b5c33787b 100644
--- a/extensions/Tumblr-GDPR/metadata.json
+++ b/lib/core-extensions/Tumblr-GDPR/metadata.json
diff --git a/p/ext.php b/p/ext.php
index 3035aae7d..f3b7b6a9e 100644
--- a/p/ext.php
+++ b/p/ext.php
@@ -7,19 +7,9 @@ if (!isset($_GET['f']) ||
 
 require(__DIR__ . '/../constants.php');
 
-/**
- * Check if a file can be served by ext.php. A valid file is under a
- * EXTENSIONS_PATH/extension_name/static/ directory.
- *
- * You should sanitize path by using the realpath() function.
- *
- * @param $path the path to the file we want to serve.
- * @return true if it can be served, false else.
- *
- */
-function is_valid_path($path) {
+function is_valid_path_extension($path, $extensionPath) {
 	// It must be under the extension path.
-	$real_ext_path = realpath(EXTENSIONS_PATH);
+	$real_ext_path = realpath($extensionPath);
 
 	//Windows compatibility
 	$real_ext_path = str_replace('\\', '/', $real_ext_path);
@@ -40,6 +30,20 @@ function is_valid_path($path) {
 	return true;
 }
 
+/**
+ * Check if a file can be served by ext.php. A valid file is under a
+ * CORE_EXTENSIONS_PATH/extension_name/static/ or THIRDPARTY_EXTENSIONS_PATH/extension_name/static/ directory.
+ *
+ * You should sanitize path by using the realpath() function.
+ *
+ * @param $path the path to the file we want to serve.
+ * @return true if it can be served, false otherwise.
+ *
+ */
+function is_valid_path($path) {
+	return is_valid_path_extension($path, CORE_EXTENSIONS_PATH) || is_valid_path_extension($path, THIRDPARTY_EXTENSIONS_PATH);
+}
+
 $file_name = urldecode($_GET['f']);
 $file_type = $_GET['t'];