From 8d1a3daa3fd7d1a4ecb7934662a76266a02ce225 Mon Sep 17 00:00:00 2001
From: Vincent Petry <pvince81@yahoo.fr>
Date: Thu, 3 Aug 2023 23:09:17 +0200
Subject: [PATCH] Allow ext storage Local to go unavailable

Whenever an external storage of type Local points at a non-existing
directory, process this as a StorageNotAvailable instead of returning
404.

This makes desktop clients ignore the folder instead of deleting it when
it becomes unavailable.

The code change was limited to external storages to avoid issues during
setup and with the default home storage.
Signed-off-by: Vincent Petry <pvince81@yahoo.fr>
---
 apps/files_external/lib/Lib/Backend/Local.php |  6 ++++++
 lib/private/Files/Storage/Local.php           |  7 +++++++
 tests/lib/Files/Storage/LocalTest.php         | 11 +++++++++++
 3 files changed, 24 insertions(+)

diff --git a/apps/files_external/lib/Lib/Backend/Local.php b/apps/files_external/lib/Lib/Backend/Local.php
index 88b251360d678..bd15cb461271b 100644
--- a/apps/files_external/lib/Lib/Backend/Local.php
+++ b/apps/files_external/lib/Lib/Backend/Local.php
@@ -26,8 +26,10 @@
 use OCA\Files_External\Lib\Auth\AuthMechanism;
 use OCA\Files_External\Lib\Auth\NullMechanism;
 use OCA\Files_External\Lib\DefinitionParameter;
+use OCA\Files_External\Lib\StorageConfig;
 use OCA\Files_External\Service\BackendService;
 use OCP\IL10N;
+use OCP\IUser;
 
 class Local extends Backend {
 	public function __construct(IL10N $l, NullMechanism $legacyAuth) {
@@ -45,4 +47,8 @@ public function __construct(IL10N $l, NullMechanism $legacyAuth) {
 			->setLegacyAuthMechanism($legacyAuth)
 		;
 	}
+
+	public function manipulateStorageConfig(StorageConfig &$storage, IUser $user = null): void {
+		$storage->setBackendOption('isExternal', true);
+	}
 }
diff --git a/lib/private/Files/Storage/Local.php b/lib/private/Files/Storage/Local.php
index 02708ed4f7d00..fdc30b492595e 100644
--- a/lib/private/Files/Storage/Local.php
+++ b/lib/private/Files/Storage/Local.php
@@ -51,6 +51,7 @@
 use OCP\Files\GenericFileException;
 use OCP\Files\IMimeTypeDetector;
 use OCP\Files\Storage\IStorage;
+use OCP\Files\StorageNotAvailableException;
 use OCP\IConfig;
 use OCP\Util;
 use Psr\Log\LoggerInterface;
@@ -95,6 +96,12 @@ public function __construct($arguments) {
 
 		// support Write-Once-Read-Many file systems
 		$this->unlinkOnTruncate = $this->config->getSystemValueBool('localstorage.unlink_on_truncate', false);
+
+		if (isset($arguments['isExternal']) && $arguments['isExternal'] && !$this->stat('')) {
+			// data dir not accessible or available, can happen when using an external storage of type Local
+			// on an unmounted system mount point
+			throw new StorageNotAvailableException('Local storage path does not exist "' . $this->getSourcePath('') . '"');
+		}
 	}
 
 	public function __destruct() {
diff --git a/tests/lib/Files/Storage/LocalTest.php b/tests/lib/Files/Storage/LocalTest.php
index e324d2b28db06..1190a2b2da043 100644
--- a/tests/lib/Files/Storage/LocalTest.php
+++ b/tests/lib/Files/Storage/LocalTest.php
@@ -139,4 +139,15 @@ public function testWriteUmaskCopy() {
 		umask($oldMask);
 		$this->assertTrue($this->instance->isUpdatable('test.txt'));
 	}
+
+	public function testUnavailableExternal() {
+		$this->expectException(\OCP\Files\StorageNotAvailableException::class);
+		$this->instance = new \OC\Files\Storage\Local(['datadir' => $this->tmpDir . '/unexist', 'isExternal' => true]);
+	}
+
+	public function testUnavailableNonExternal() {
+		$this->instance = new \OC\Files\Storage\Local(['datadir' => $this->tmpDir . '/unexist']);
+		// no exception thrown
+		$this->assertNotNull($this->instance);
+	}
 }