Proper message shown when private links accessed

apps/files/lib/Controller/ViewController.php

@@ -281,9 +281,12 @@ public function showFile($fileId) {
 		$params = [];
 
 		if (empty($files) && $this->appManager->isEnabledForUser('files_trashbin')) {
-			$baseFolder = $this->rootFolder->get($uid . '/files_trashbin/files/');
-			$files = $baseFolder->getById($fileId);
-			$params['view'] = 'trashbin';
+			// Access files_trashbin if it exists
+			if ( $this->rootFolder->nodeExists($uid . '/files_trashbin/files/')) {
+				$baseFolder = $this->rootFolder->get($uid . '/files_trashbin/files/');
+				$files = $baseFolder->getById($fileId);
+				$params['view'] = 'trashbin';
+			}
 		}
 
 		if (!empty($files)) {
@@ -299,6 +302,12 @@ public function showFile($fileId) {
 			}
 			return new RedirectResponse($this->urlGenerator->linkToRoute('files.view.index', $params));
 		}
+
+		if ( $this->userSession->isLoggedIn() and empty($files)) {
+			$param["error"] = $this->l10n->t("You don't have permissions to access this file/folder - Please contact the owner to share it with you.");
+			return new TemplateResponse("core", 'error', ["errors" => [$param]], 'guest');
+		}
+
 		throw new \OCP\Files\NotFoundException();
 	}
 }

apps/files/tests/Controller/ViewControllerTest.php

@@ -428,6 +428,10 @@ public function testShowFileRouteWithTrashedFile($useShowFile) {
 			->with('files_trashbin')
 			->will($this->returnValue(true));
 
+		$this->rootFolder->expects($this->once())
+			->method('nodeExists')
+			->will($this->returnValue(true));
+
 		$parentNode = $this->createMock('\OCP\Files\Folder');
 		$parentNode->expects($this->once())
 			->method('getPath')
@@ -440,7 +444,8 @@ public function testShowFileRouteWithTrashedFile($useShowFile) {
 			->method('get')
 			->with('testuser1/files/')
 			->will($this->returnValue($baseFolderFiles));
-		$this->rootFolder->expects($this->at(1))
+		//The index is pointing to 2, because nodeExists internally calls get method.
+		$this->rootFolder->expects($this->at(2))
 			->method('get')
 			->with('testuser1/files_trashbin/files/')
 			->will($this->returnValue($baseFolderTrash));

core/Controller/LoginController.php

@@ -166,6 +166,21 @@ public function showLoginForm($user, $redirect_url, $remember_login) {
 			$parameters['user_autofocus'] = true;
 		}
 
+		/**
+		 * If redirect_url is not empty and remember_login is null and
+		 * user not logged in and check if the string
+		 * webroot+"/index.php/f/" is in redirect_url then
+		 * user is trying to access files for which he needs to login.
+		 */
+
+		if ((!empty($redirect_url)) and ($remember_login === null) and
+			($this->userSession->isLoggedIn() === false) and
+			(strpos($this->urlGenerator->getAbsoluteURL(urldecode($redirect_url)),
+				$this->urlGenerator->getAbsoluteURL('/index.php/f/')) !== false)) {
+
+			$parameters['accessLink'] = true;
+		}
+
 		return new TemplateResponse(
 			$this->appName, 'login', $parameters, 'guest'
 		);

core/templates/login.php

@@ -66,6 +66,11 @@
 				<?php p($l->t('Wrong password.')); ?>
 			</p>
 		<?php } ?>
+		<?php if (!empty($_['accessLink'])) { ?>
+			<p class="warning">
+				<?php p($l->t("You are trying to access a private link. Please log in first.")) ?>
+			</p>
+		<?php } ?>
 		<?php if ($_['rememberLoginAllowed'] === true) : ?>
 		<div class="remember-login-container">
 			<?php if ($_['rememberLoginState'] === 0) { ?>

tests/Core/Controller/LoginControllerTest.php

@@ -137,6 +137,23 @@ public function testShowLoginFormForLoggedInUsers() {
 		$this->assertEquals($expectedResponse, $this->loginController->showLoginForm('', '', ''));
 	}
 
+	public function testResponseForNotLoggedinUser() {
+		$params = [
+			'messages' => Array (),
+			'loginName' => '',
+			'user_autofocus' => true,
+			'redirect_url' => '%2Findex.php%2Ff%2F17',
+			'canResetPassword' => true,
+			'resetPasswordLink' => null,
+			'alt_login' => Array (),
+			'rememberLoginAllowed' => false,
+			'rememberLoginState' => 0
+		];
+
+		$expectedResponse = new TemplateResponse('core', 'login', $params, 'guest');
+		$this->assertEquals($expectedResponse, $this->loginController->showLoginForm('', '%2Findex.php%2Ff%2F17', ''));
+	}
+
 	public function testShowLoginFormWithErrorsInSession() {
 		$this->userSession
 			->expects($this->once())