Preserve symbolic links from sync clients

apps/dav/composer/composer/autoload_classmap.php

@@ -343,6 +343,7 @@
     'OCA\\DAV\\Upload\\FutureFile' => $baseDir . '/../lib/Upload/FutureFile.php',
     'OCA\\DAV\\Upload\\PartFile' => $baseDir . '/../lib/Upload/PartFile.php',
     'OCA\\DAV\\Upload\\RootCollection' => $baseDir . '/../lib/Upload/RootCollection.php',
+    'OCA\\DAV\\Upload\\SymlinkPlugin' => $baseDir . '/../lib/Upload/SymlinkPlugin.php',
     'OCA\\DAV\\Upload\\UploadFile' => $baseDir . '/../lib/Upload/UploadFile.php',
     'OCA\\DAV\\Upload\\UploadFolder' => $baseDir . '/../lib/Upload/UploadFolder.php',
     'OCA\\DAV\\Upload\\UploadHome' => $baseDir . '/../lib/Upload/UploadHome.php',

apps/dav/composer/composer/autoload_static.php

@@ -358,6 +358,7 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\Upload\\FutureFile' => __DIR__ . '/..' . '/../lib/Upload/FutureFile.php',
         'OCA\\DAV\\Upload\\PartFile' => __DIR__ . '/..' . '/../lib/Upload/PartFile.php',
         'OCA\\DAV\\Upload\\RootCollection' => __DIR__ . '/..' . '/../lib/Upload/RootCollection.php',
+        'OCA\\DAV\\Upload\\SymlinkPlugin' => __DIR__ . '/..' . '/../lib/Upload/SymlinkPlugin.php',
         'OCA\\DAV\\Upload\\UploadFile' => __DIR__ . '/..' . '/../lib/Upload/UploadFile.php',
         'OCA\\DAV\\Upload\\UploadFolder' => __DIR__ . '/..' . '/../lib/Upload/UploadFolder.php',
         'OCA\\DAV\\Upload\\UploadHome' => __DIR__ . '/..' . '/../lib/Upload/UploadHome.php',

apps/dav/lib/BulkUpload/BulkUploadPlugin.php

@@ -23,6 +23,7 @@
 
 namespace OCA\DAV\BulkUpload;
 
+use OC\Files\SymlinkManager;
 use OCA\DAV\Connector\Sabre\MtimeSanitizer;
 use OCP\AppFramework\Http;
 use OCP\Files\DavUtil;
@@ -37,12 +38,18 @@ class BulkUploadPlugin extends ServerPlugin {
 	private Folder $userFolder;
 	private LoggerInterface $logger;
 
+	/**
+	 * @var SymlinkManager
+	 */
+	private $symlinkManager;
+
 	public function __construct(
 		Folder $userFolder,
 		LoggerInterface $logger
 	) {
 		$this->userFolder = $userFolder;
 		$this->logger = $logger;
+		$this->symlinkManager = new SymlinkManager();
 	}
 
 	/**
@@ -93,6 +100,14 @@ public function httpPost(RequestInterface $request, ResponseInterface $response)
 				$node->touch($mtime);
 				$node = $this->userFolder->getById($node->getId())[0];
 
+				if (isset($headers['oc-file-type']) && $headers['oc-file-type'] == 1) {
+					$this->symlinkManager->storeSymlink($node);
+				} elseif ($this->symlinkManager->isSymlink($node)) {
+					// uploaded file is not a symlink, but there was a symlink
+					// at the same location before
+					$this->symlinkManager->deleteSymlink($node);
+				}
+
 				$writtenFiles[$headers['x-file-path']] = [
 					"error" => false,
 					"etag" => $node->getETag(),

apps/dav/lib/Connector/Sabre/File.php

@@ -125,7 +125,7 @@ public function __construct(View $view, FileInfo $info, IManager $shareManager =
 	 * different object on a subsequent GET you are strongly recommended to not
 	 * return an ETag, and just return null.
 	 *
-	 * @param resource $data
+	 * @param resource|string $data
 	 *
 	 * @throws Forbidden
 	 * @throws UnsupportedMediaType

apps/dav/lib/Connector/Sabre/FilesPlugin.php

@@ -35,6 +35,7 @@
 namespace OCA\DAV\Connector\Sabre;
 
 use OC\AppFramework\Http\Request;
+use OC\Files\SymlinkManager;
 use OCP\Constants;
 use OCP\Files\ForbiddenException;
 use OCP\Files\StorageNotAvailableException;
@@ -73,6 +74,7 @@ class FilesPlugin extends ServerPlugin {
 	public const LASTMODIFIED_PROPERTYNAME = '{DAV:}lastmodified';
 	public const CREATIONDATE_PROPERTYNAME = '{DAV:}creationdate';
 	public const DISPLAYNAME_PROPERTYNAME = '{DAV:}displayname';
+	public const RESOURCETYPE_PROPERTYNAME = '{DAV:}resourcetype';
 	public const OWNER_ID_PROPERTYNAME = '{http://owncloud.org/ns}owner-id';
 	public const OWNER_DISPLAY_NAME_PROPERTYNAME = '{http://owncloud.org/ns}owner-display-name';
 	public const CHECKSUMS_PROPERTYNAME = '{http://owncloud.org/ns}checksums';
@@ -103,6 +105,7 @@ class FilesPlugin extends ServerPlugin {
 	private IConfig $config;
 	private IRequest $request;
 	private IPreview $previewManager;
+	private SymlinkManager $symlinkManager;
 
 	public function __construct(Tree $tree,
 		IConfig $config,
@@ -118,6 +121,7 @@ public function __construct(Tree $tree,
 		$this->isPublic = $isPublic;
 		$this->downloadAttachment = $downloadAttachment;
 		$this->previewManager = $previewManager;
+		$this->symlinkManager = new SymlinkManager();
 	}
 
 	/**
@@ -159,7 +163,8 @@ public function initialize(Server $server) {
 		$this->server->on('propPatch', [$this, 'handleUpdateProperties']);
 		$this->server->on('afterBind', [$this, 'sendFileIdHeader']);
 		$this->server->on('afterWriteContent', [$this, 'sendFileIdHeader']);
-		$this->server->on('afterMethod:GET', [$this,'httpGet']);
+		$this->server->on('method:GET', [$this,'httpGet']);
+		$this->server->on('afterMethod:GET', [$this,'afterHttpGet']);
 		$this->server->on('afterMethod:GET', [$this, 'handleDownloadToken']);
 		$this->server->on('afterResponse', function ($request, ResponseInterface $response) {
 			$body = $response->getBody();
@@ -224,13 +229,35 @@ public function handleDownloadToken(RequestInterface $request, ResponseInterface
 		}
 	}
 
+	public function httpGet(RequestInterface $request, ResponseInterface $response): bool {
+		// only handle symlinks
+		$node = $this->tree->getNodeForPath($request->getPath());
+		if (!($node instanceof \OCA\DAV\Connector\Sabre\File
+				&& $this->symlinkManager->isSymlink($node->getFileInfo()))) {
+			return true;
+		}
+
+		$date = new \DateTime();
+		$date->setTimestamp($node->getLastModified());
+		$date = $date->setTimezone(new \DateTimeZone('UTC'));
+		$response->setHeader('Last-Modified', $date->format('D, d M Y H:i:s').' GMT');
+		$response->setHeader('OC-File-Type', '1');
+		$response->setHeader('OC-ETag', $node->getEtag());
+		$response->setHeader('ETag', $node->getEtag());
+		$response->setBody($node->get());
+		$response->setStatus(200);
+		// do not continue processing this request
+		return false;
+	}
+
+
 	/**
 	 * Add headers to file download
 	 *
 	 * @param RequestInterface $request
 	 * @param ResponseInterface $response
 	 */
-	public function httpGet(RequestInterface $request, ResponseInterface $response) {
+	public function afterHttpGet(RequestInterface $request, ResponseInterface $response): void {
 		// Only handle valid files
 		$node = $this->tree->getNodeForPath($request->getPath());
 		if (!($node instanceof IFile)) {
@@ -431,6 +458,14 @@ public function handleGetProperties(PropFind $propFind, \Sabre\DAV\INode $node)
 			$propFind->handle(self::UPLOAD_TIME_PROPERTYNAME, function () use ($node) {
 				return $node->getFileInfo()->getUploadTime();
 			});
+
+			$propFind->handle(self::RESOURCETYPE_PROPERTYNAME, function() use ($node) {
+				$info = $node->getFileInfo();
+				if ($this->symlinkManager->isSymlink($info)) {
+					return new \Sabre\DAV\Xml\Property\ResourceType(['{DAV:}symlink']);
+				}
+				return null;
+			});
 		}
 
 		if ($node instanceof Directory) {

apps/dav/lib/Server.php

@@ -74,6 +74,7 @@
 use OCA\DAV\SystemTag\SystemTagPlugin;
 use OCA\DAV\Upload\ChunkingPlugin;
 use OCA\DAV\Upload\ChunkingV2Plugin;
+use OCA\DAV\Upload\SymlinkPlugin;
 use OCP\AppFramework\Http\Response;
 use OCP\Diagnostics\IEventLogger;
 use OCP\EventDispatcher\IEventDispatcher;
@@ -222,6 +223,7 @@ public function __construct(IRequest $request, string $baseUri) {
 		$this->server->addPlugin(new RequestIdHeaderPlugin(\OC::$server->get(IRequest::class)));
 		$this->server->addPlugin(new ChunkingV2Plugin(\OCP\Server::get(ICacheFactory::class)));
 		$this->server->addPlugin(new ChunkingPlugin());
+		$this->server->addPlugin(new SymlinkPlugin($logger));
 
 		// allow setup of additional plugins
 		$dispatcher->dispatch('OCA\DAV\Connector\Sabre::addPlugin', $event);

apps/dav/lib/Upload/SymlinkPlugin.php

@@ -0,0 +1,169 @@
+<?php
+
+declare(strict_types=1);
+/*
+ * @copyright Copyright (c) 2023 Tamino Bauknecht <[email protected]>
+ *
+ * @author Tamino Bauknecht <[email protected]>
+ *
+ * @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 OCA\DAV\Upload;
+
+use OC\Files\SymlinkManager;
+use Psr\Log\LoggerInterface;
+use Sabre\DAV\Server;
+use Sabre\DAV\ServerPlugin;
+use Sabre\HTTP\RequestInterface;
+use Sabre\HTTP\ResponseInterface;
+
+class SymlinkPlugin extends ServerPlugin {
+	/**
+	 * @var Server
+	 *
+	 * @psalm-suppress PropertyNotSetInConstructor
+	 */
+	private $server;
+	/** @var SymlinkManager */
+	private $symlinkManager;
+	/** @var LoggerInterface */
+	private $logger;
+
+	public function __construct(LoggerInterface $logger) {
+		$this->symlinkManager = new SymlinkManager();
+		$this->logger = $logger;
+	}
+
+	/**
+	 * @inheritdoc
+	 */
+	public function initialize(Server $server): void {
+		$server->on('method:PUT', [$this, 'httpPut']);
+		$server->on('method:DELETE', [$this, 'httpDelete']);
+		$server->on('afterMove', [$this, 'afterMove']);
+		$server->on('afterCopy', [$this, 'afterCopy']);
+
+		$this->server = $server;
+	}
+
+	public function httpPut(RequestInterface $request, ResponseInterface $response): bool {
+		if ($request->hasHeader('OC-File-Type') && $request->getHeader('OC-File-Type') == 1) {
+			$symlinkPath = $request->getPath();
+			$symlinkName = basename($symlinkPath);
+			$symlinkTarget = $request->getBodyAsString();
+			$parentPath = dirname($symlinkPath);
+			$parentNode = $this->server->tree->getNodeForPath($parentPath);
+			if (!$parentNode instanceof \Sabre\DAV\ICollection) {
+				throw new \Sabre\DAV\Exception\Forbidden("Directory does not allow creation of files - failed to upload '$symlinkName'");
+			}
+			$etag = $parentNode->createFile($symlinkName);
+			$symlinkNode = $parentNode->getChild($symlinkName);
+			if (!$symlinkNode instanceof \OCA\DAV\Connector\Sabre\File) {
+				throw new \Sabre\DAV\Exception\NotFound("Failed to get newly created file '$symlinkName'");
+			}
+			$symlinkNode->put($symlinkTarget);
+			$this->symlinkManager->storeSymlink($symlinkNode->getFileInfo());
+
+			if ($etag) {
+				$response->setHeader('OC-ETag', $etag);
+			}
+			$response->setStatus(201);
+			return false; // this request was handled already
+		} elseif ($this->server->tree->nodeExists($request->getPath())) {
+			$node = $this->server->tree->getNodeForPath($request->getPath());
+			if (!$node instanceof \OCA\DAV\Connector\Sabre\File) {
+				// cannot check if file was symlink before - let's hope it's not
+				$this->logger->warning('Unable to check if there was a symlink
+					before at the same location');
+				return true;
+			}
+			// if the newly uploaded file is not a symlink,
+			// but there was a symlink at the same path before
+			if ($this->symlinkManager->isSymlink($node->getFileInfo())) {
+				$this->symlinkManager->deleteSymlink($node->getFileInfo());
+			}
+		}
+		return true; // continue handling this request
+	}
+
+	public function httpDelete(RequestInterface $request, ResponseInterface $response): bool {
+		$path = $request->getPath();
+		$node = $this->server->tree->getNodeForPath($path);
+		if (!$node instanceof \OCA\DAV\Connector\Sabre\Node) {
+			return true;
+		}
+		$info = $node->getFileInfo();
+		if ($this->symlinkManager->isSymlink($info)) {
+			if (!$this->symlinkManager->deleteSymlink($info)) {
+				$symlinkName = $info->getName();
+				throw new \Sabre\DAV\Exception\NotFound("Unable to delete symlink '$symlinkName'!");
+			}
+		}
+		// always propagate to trigger deletion of regular file representing symlink in filesystem
+		return true;
+	}
+
+	public function afterMove(string $source, string $destination): void {
+		// source node does not exist anymore, thus use still existing parent
+		$sourceParentNode = dirname($source);
+		$sourceParentNode = $this->server->tree->getNodeForPath($sourceParentNode);
+		if (!$sourceParentNode instanceof \OCA\DAV\Connector\Sabre\Node) {
+			throw new \Sabre\DAV\Exception\NotImplemented('Unable to check if moved file is a symlink!');
+		}
+		$destinationNode = $this->server->tree->getNodeForPath($destination);
+		if (!$destinationNode instanceof \OCA\DAV\Connector\Sabre\Node) {
+			throw new \Sabre\DAV\Exception\NotImplemented('Unable to set symlink information on move destination!');
+		}
+
+		$sourceInfo = new \OC\Files\FileInfo(
+			$source,
+			$sourceParentNode->getFileInfo()->getStorage(),
+			$sourceParentNode->getInternalPath() . '/' . basename($source),
+			[],
+			$sourceParentNode->getFileInfo()->getMountPoint());
+		$destinationInfo = $destinationNode->getFileInfo();
+
+		if ($this->symlinkManager->isSymlink($sourceInfo)) {
+			$this->symlinkManager->deleteSymlink($sourceInfo);
+			$this->symlinkManager->storeSymlink($destinationInfo);
+		} elseif ($this->symlinkManager->isSymlink($destinationInfo)) {
+			// source was not a symlink, but destination was a symlink before
+			$this->symlinkManager->deleteSymlink($destinationInfo);
+		}
+	}
+
+	public function afterCopy(string $source, string $destination): void {
+		$sourceNode = $this->server->tree->getNodeForPath($source);
+		if (!$sourceNode instanceof \OCA\DAV\Connector\Sabre\Node) {
+			throw new \Sabre\DAV\Exception\NotImplemented(
+				'Unable to check if copied file is a symlink!');
+		}
+		$destinationNode = $this->server->tree->getNodeForPath($destination);
+		if (!$destinationNode instanceof \OCA\DAV\Connector\Sabre\Node) {
+			throw new \Sabre\DAV\Exception\NotImplemented(
+				'Unable to set symlink information on copy destination!');
+		}
+
+		$sourceInfo = $sourceNode->getFileInfo();
+		$destinationInfo = $destinationNode->getFileInfo();
+
+		if ($this->symlinkManager->isSymlink($sourceInfo)) {
+			$this->symlinkManager->storeSymlink($destinationInfo);
+		}
+	}
+}

core/Controller/PreviewController.php

@@ -27,6 +27,7 @@
  */
 namespace OC\Core\Controller;
 
+use OC\Files\SymlinkManager;
 use OCA\Files_Sharing\SharedStorage;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http;
@@ -42,6 +43,12 @@
 use OCP\Preview\IMimeIconProvider;
 
 class PreviewController extends Controller {
+	private const SYMLINK_PREVIEW_ICON_PATH = '/core/img/filetypes/link.svg';
+	/**
+	 * @var SymlinkManager
+	 */
+	private $symlinkManager;
+
 	public function __construct(
 		string $appName,
 		IRequest $request,
@@ -51,6 +58,8 @@ public function __construct(
 		private IMimeIconProvider $mimeIconProvider,
 	) {
 		parent::__construct($appName, $request);
+
+		$this->symlinkManager = new SymlinkManager();
 	}
 
 	/**
@@ -169,6 +178,14 @@ private function fetchPreview(
 			}
 		}
 
+		if ($this->symlinkManager->isSymlink($node)) {
+			if ($url = \OC::$server->get(\OCP\IURLGenerator::class)->getAbsoluteURL(
+				self::SYMLINK_PREVIEW_ICON_PATH
+			)) {
+				return new RedirectResponse($url);
+			}
+		}
+
 		try {
 			$f = $this->preview->getPreview($node, $x, $y, !$a, $mode);
 			$response = new FileDisplayResponse($f, Http::STATUS_OK, [