Throw exception on `getPath` if file does not exist

Currently the `getPath` methods returned `NULL` in case when a file with the specified ID does not exist. This however mandates that developers are checking for the `NULL` case and if they do not the door for bugs with all kind of impact is widely opened.

This is especially harmful if used in context with Views where the final result is limited based on the result of `getPath`, if `getPath` returns `NULL` PHP type juggles this to an empty string resulting in all possible kind of bugs.

While one could argue that this is a misusage of the API the fact is that it is very often misused and an exception will trigger an immediate stop of execution as well as log this behaviour and show a pretty error page.

I also adjusted some usages where I believe that we need to catch these errors, in most cases this is though simply an error that should hard-fail.

14 files changed, 121 insertions, 54 deletions

diff --git a/apps/files_sharing/api/server2server.php b/apps/files_sharing/api/server2server.php
index 2e0468039b4..832193f2b99 100644
--- a/apps/files_sharing/api/server2server.php
+++ b/apps/files_sharing/api/server2server.php
@@ -25,6 +25,7 @@
 namespace OCA\Files_Sharing\API;
 
 use OCA\Files_Sharing\Activity;
+use OCP\Files\NotFoundException;
 
 class Server2Server {
 
@@ -264,7 +265,11 @@ class Server2Server {
 	private function getFile($user, $fileSource) {
 		\OC_Util::setupFS($user);
 
-		$file = \OC\Files\Filesystem::getPath($fileSource);
+		try {
+			$file = \OC\Files\Filesystem::getPath($fileSource);
+		} catch (NotFoundException $e) {
+			$file = null;
+		}
 		$args = \OC\Files\Filesystem::is_dir($file) ? array('dir' => $file) : array('dir' => dirname($file), 'scrollto' => $file);
 		$link = \OCP\Util::linkToAbsolute('files', 'index.php', $args);
 
diff --git a/apps/files_sharing/lib/controllers/sharecontroller.php b/apps/files_sharing/lib/controllers/sharecontroller.php
index 616b64e6c59..8a4e67eccf6 100644
--- a/apps/files_sharing/lib/controllers/sharecontroller.php
+++ b/apps/files_sharing/lib/controllers/sharecontroller.php
@@ -333,8 +333,7 @@ class ShareController extends Controller {
 				OC_Util::tearDownFS();
 				OC_Util::setupFS($rootLinkItem['uid_owner']);
 				$path = Filesystem::getPath($linkItem['file_source']);
-
-				if(!empty($path) && Filesystem::isReadable($path)) {
+				if(Filesystem::isReadable($path)) {
 					return $path;
 				}
 			}
diff --git a/apps/files_sharing/lib/helper.php b/apps/files_sharing/lib/helper.php
index b15f70fcde3..beb8c69c415 100644
--- a/apps/files_sharing/lib/helper.php
+++ b/apps/files_sharing/lib/helper.php
@@ -28,6 +28,8 @@
  */
 namespace OCA\Files_Sharing;
 
+use OCP\Files\NotFoundException;
+
 class Helper {
 
 	public static function registerHooks() {
@@ -48,6 +50,7 @@ class Helper {
 	 * @param string $token string share token
 	 * @param string $relativePath optional path relative to the share
 	 * @param string $password optional password
+	 * @return array
 	 */
 	public static function setupFromToken($token, $relativePath = null, $password = null) {
 		\OC_User::setIncognitoMode(true);
@@ -71,10 +74,11 @@ class Helper {
 			\OCP\JSON::checkUserExists($rootLinkItem['uid_owner']);
 			\OC_Util::tearDownFS();
 			\OC_Util::setupFS($rootLinkItem['uid_owner']);
-			$path = \OC\Files\Filesystem::getPath($linkItem['file_source']);
 		}
 
-		if ($path === null) {
+		try {
+			$path = \OC\Files\Filesystem::getPath($linkItem['file_source']);
+		} catch (NotFoundException $e) {
 			\OCP\Util::writeLog('share', 'could not resolve linkItem', \OCP\Util::DEBUG);
 			\OC_Response::setStatus(404);
 			\OCP\JSON::error(array('success' => false));
diff --git a/apps/files_sharing/lib/propagation/recipientpropagator.php b/apps/files_sharing/lib/propagation/recipientpropagator.php
index 8e064e2ee54..f0941ce6cb7 100644
--- a/apps/files_sharing/lib/propagation/recipientpropagator.php
+++ b/apps/files_sharing/lib/propagation/recipientpropagator.php
@@ -25,6 +25,7 @@ namespace OCA\Files_Sharing\Propagation;
 use OC\Files\Cache\ChangePropagator;
 use OC\Files\View;
 use OC\Share\Share;
+use OCP\Files\NotFoundException;
 
 /**
  * Propagate etags for share recipients
@@ -128,6 +129,9 @@ class RecipientPropagator {
 
 	protected $propagatingIds = [];
 
+	/**
+	 * @param int $id
+	 */
 	public function propagateById($id) {
 		if (isset($this->propagatingIds[$id])) {
 			return;
@@ -142,7 +146,13 @@ class RecipientPropagator {
 			if ($share['share_with'] === $this->userId) {
 				$user = $share['uid_owner'];
 				$view = new View('/' . $user . '/files');
-				$path = $view->getPath($share['file_source']);
+
+				try {
+					$path = $view->getPath($share['file_source']);
+				} catch (NotFoundException $e) {
+					$path = null;
+				}
+
 				$watcher = new ChangeWatcher($view, $this->manager->getSharePropagator($user));
 				$watcher->writeHook(['path' => $path]);
 			}
diff --git a/apps/files_sharing/lib/share/file.php b/apps/files_sharing/lib/share/file.php
index 6c676f47a0c..67ef3937e6d 100644
--- a/apps/files_sharing/lib/share/file.php
+++ b/apps/files_sharing/lib/share/file.php
@@ -40,15 +40,16 @@ class OC_Share_Backend_File implements OCP\Share_Backend_File_Dependent {
 	private $path;
 
 	public function isValidSource($itemSource, $uidOwner) {
-		$path = \OC\Files\Filesystem::getPath($itemSource);
-		if ($path) {
+		try {
+			$path = \OC\Files\Filesystem::getPath($itemSource);
 			// FIXME: attributes should not be set here,
 			// keeping this pattern for now to avoid unexpected
 			// regressions
 			$this->path = \OC\Files\Filesystem::normalizePath(basename($path));
 			return true;
+		} catch (\OCP\Files\NotFoundException $e) {
+			return false;
 		}
-		return false;
 	}
 
 	public function getFilePath($itemSource, $uidOwner) {
@@ -57,12 +58,13 @@ class OC_Share_Backend_File implements OCP\Share_Backend_File_Dependent {
 			$this->path = null;
 			return $path;
 		} else {
-			$path = \OC\Files\Filesystem::getPath($itemSource);
-			if ($path) {
+			try {
+				$path = \OC\Files\Filesystem::getPath($itemSource);
 				return $path;
+			} catch (\OCP\Files\NotFoundException $e) {
+				return false;
 			}
 		}
-		return false;
 	}
 
 	/**
diff --git a/apps/files_sharing/tests/controller/sharecontroller.php b/apps/files_sharing/tests/controller/sharecontroller.php
index 0b56aafc8a9..db5eb75d761 100644
--- a/apps/files_sharing/tests/controller/sharecontroller.php
+++ b/apps/files_sharing/tests/controller/sharecontroller.php
@@ -199,8 +199,7 @@ class ShareControllerTest extends \Test\TestCase {
 	}
 
 	/**
-	 * @expectedException \Exception
-	 * @expectedExceptionMessage No file found belonging to file.
+	 * @expectedException \OCP\Files\NotFoundException
 	 */
 	public function testShowShareWithDeletedFile() {
 		$this->container['UserManager']->expects($this->once())
@@ -216,8 +215,7 @@ class ShareControllerTest extends \Test\TestCase {
 	}
 
 	/**
-	 * @expectedException \Exception
-	 * @expectedExceptionMessage No file found belonging to file.
+	 * @expectedException \OCP\Files\NotFoundException
 	 */
 	public function testDownloadShareWithDeletedFile() {
 		$this->container['UserManager']->expects($this->once())
diff --git a/apps/files_sharing/tests/etagpropagation.php b/apps/files_sharing/tests/etagpropagation.php
index 2490fef03e1..9f9b65ed527 100644
--- a/apps/files_sharing/tests/etagpropagation.php
+++ b/apps/files_sharing/tests/etagpropagation.php
@@ -173,7 +173,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsChanged($users, 'sub1/sub2');
 	}
 
-	private function assertAllUnchaged() {
+	private function assertAllUnchanged() {
 		$users = [self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4];
 		$this->assertEtagsNotChanged($users);
@@ -186,7 +186,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerWritesToSingleFileShare() {
@@ -195,7 +195,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsNotChanged([self::TEST_FILES_SHARING_API_USER4, self::TEST_FILES_SHARING_API_USER3]);
 		$this->assertEtagsChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerWritesToShareWithReshare() {
@@ -204,7 +204,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerRenameInShare() {
@@ -214,7 +214,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerRenameInReShare() {
@@ -223,7 +223,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerRenameIntoReShare() {
@@ -232,7 +232,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerRenameOutOfReShare() {
@@ -241,7 +241,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerDeleteInShare() {
@@ -251,7 +251,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerDeleteInReShare() {
@@ -260,7 +260,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testOwnerUnshares() {
@@ -283,7 +283,7 @@ class EtagPropagation extends TestCase {
 			self::TEST_FILES_SHARING_API_USER4,
 		]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientUnsharesFromSelf() {
@@ -298,7 +298,7 @@ class EtagPropagation extends TestCase {
 			self::TEST_FILES_SHARING_API_USER4,
 		]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientWritesToShare() {
@@ -308,7 +308,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientWritesToReshare() {
@@ -317,7 +317,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientWritesToOtherRecipientsReshare() {
@@ -326,7 +326,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientRenameInShare() {
@@ -336,7 +336,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientRenameInReShare() {
@@ -345,7 +345,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientRenameResharedFolder() {
@@ -356,7 +356,7 @@ class EtagPropagation extends TestCase {
 
 		$this->assertEtagsChanged([self::TEST_FILES_SHARING_API_USER2], 'sub1');
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientDeleteInShare() {
@@ -366,7 +366,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientDeleteInReShare() {
@@ -375,7 +375,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testReshareRecipientWritesToReshare() {
@@ -384,7 +384,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testReshareRecipientRenameInReShare() {
@@ -393,7 +393,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testReshareRecipientDeleteInReShare() {
@@ -402,7 +402,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2,
 			self::TEST_FILES_SHARING_API_USER3, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testRecipientUploadInDirectReshare() {
@@ -411,7 +411,7 @@ class EtagPropagation extends TestCase {
 		$this->assertEtagsNotChanged([self::TEST_FILES_SHARING_API_USER3]);
 		$this->assertEtagsChanged([self::TEST_FILES_SHARING_API_USER1, self::TEST_FILES_SHARING_API_USER2, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 
 	public function testEtagChangeOnPermissionsChange() {
@@ -424,6 +424,6 @@ class EtagPropagation extends TestCase {
 
 		$this->assertEtagsForFoldersChanged([self::TEST_FILES_SHARING_API_USER2, self::TEST_FILES_SHARING_API_USER4]);
 
-		$this->assertAllUnchaged();
+		$this->assertAllUnchanged();
 	}
 }
diff --git a/apps/files_trashbin/lib/trashbin.php b/apps/files_trashbin/lib/trashbin.php
index 839a47a7bf2..9eada31f5df 100644
--- a/apps/files_trashbin/lib/trashbin.php
+++ b/apps/files_trashbin/lib/trashbin.php
@@ -41,6 +41,7 @@ use OC\Files\Filesystem;
 use OC\Files\View;
 use OCA\Files_Trashbin\AppInfo\Application;
 use OCA\Files_Trashbin\Command\Expire;
+use OCP\Files\NotFoundException;
 
 class Trashbin {
 
@@ -64,15 +65,24 @@ class Trashbin {
 		self::getUidAndFilename($params['path']);
 	}
 
+	/**
+	 * @param string $filename
+	 * @return array
+	 * @throws \OC\User\NoUserException
+	 */
 	public static function getUidAndFilename($filename) {
 		$uid = \OC\Files\Filesystem::getOwner($filename);
 		\OC\Files\Filesystem::initMountPoints($uid);
 		if ($uid != \OCP\User::getUser()) {
 			$info = \OC\Files\Filesystem::getFileInfo($filename);
 			$ownerView = new \OC\Files\View('/' . $uid . '/files');
-			$filename = $ownerView->getPath($info['fileid']);
+			try {
+				$filename = $ownerView->getPath($info['fileid']);
+			} catch (NotFoundException $e) {
+				$filename = null;
+			}
 		}
-		return array($uid, $filename);
+		return [$uid, $filename];
 	}
 
 	/**
diff --git a/apps/files_versions/lib/storage.php b/apps/files_versions/lib/storage.php
index dd8af1b8d18..6737bf20f90 100644
--- a/apps/files_versions/lib/storage.php
+++ b/apps/files_versions/lib/storage.php
@@ -44,6 +44,7 @@ namespace OCA\Files_Versions;
 use OCA\Files_Versions\AppInfo\Application;
 use OCA\Files_Versions\Command\Expire;
 use OCP\Lock\ILockingProvider;
+use OCP\Files\NotFoundException;
 
 class Storage {
 
@@ -74,15 +75,24 @@ class Storage {
 	/** @var \OCA\Files_Versions\AppInfo\Application */
 	private static $application;
 
+	/**
+	 * @param string $filename
+	 * @return array
+	 * @throws \OC\User\NoUserException
+	 */
 	public static function getUidAndFilename($filename) {
 		$uid = \OC\Files\Filesystem::getOwner($filename);
 		\OC\Files\Filesystem::initMountPoints($uid);
 		if ( $uid != \OCP\User::getUser() ) {
 			$info = \OC\Files\Filesystem::getFileInfo($filename);
 			$ownerView = new \OC\Files\View('/'.$uid.'/files');
-			$filename = $ownerView->getPath($info['fileid']);
+			try {
+				$filename = $ownerView->getPath($info['fileid']);
+			} catch (NotFoundException $e) {
+				$filename = null;
+			}
 		}
-		return array($uid, $filename);
+		return [$uid, $filename];
 	}
 
 	/**
diff --git a/apps/files_versions/tests/versions.php b/apps/files_versions/tests/versions.php
index 2979de2ac98..b9bc0932a84 100644
--- a/apps/files_versions/tests/versions.php
+++ b/apps/files_versions/tests/versions.php
@@ -759,7 +759,11 @@ class Test_Files_Versioning extends \Test\TestCase {
 		);
 	}
 
-	private function createAndCheckVersions($view, $path) {
+	/**
+	 * @param \OC\Files\View $view
+	 * @param string $path
+	 */
+	private function createAndCheckVersions(\OC\Files\View $view, $path) {
 		$view->file_put_contents($path, 'test file');
 		$view->file_put_contents($path, 'version 1');
 		$view->file_put_contents($path, 'version 2');
@@ -782,7 +786,6 @@ class Test_Files_Versioning extends \Test\TestCase {
 	/**
 	 * @param string $user
 	 * @param bool $create
-	 * @param bool $password
 	 */
 	public static function loginHelper($user, $create = false) {
 
diff --git a/lib/private/files/filesystem.php b/lib/private/files/filesystem.php
index babf1c7d4ea..0f7508b8f26 100644
--- a/lib/private/files/filesystem.php
+++ b/lib/private/files/filesystem.php
@@ -62,6 +62,7 @@ use OC\Cache\File;
 use OC\Files\Config\MountProviderCollection;
 use OC\Files\Storage\StorageFactory;
 use OCP\Files\Config\IMountProvider;
+use OCP\Files\NotFoundException;
 use OCP\IUserManager;
 
 class Filesystem {
@@ -855,7 +856,7 @@ class Filesystem {
 	 * @param string $path
 	 * @param boolean $includeMountPoints whether to add mountpoint sizes,
 	 * defaults to true
-	 * @return \OC\Files\FileInfo
+	 * @return \OC\Files\FileInfo|bool False if file does not exist
 	 */
 	public static function getFileInfo($path, $includeMountPoints = true) {
 		return self::$defaultInstance->getFileInfo($path, $includeMountPoints);
@@ -891,6 +892,7 @@ class Filesystem {
 	 * Note that the resulting path is not guaranteed to be unique for the id, multiple paths can point to the same file
 	 *
 	 * @param int $id
+	 * @throws NotFoundException
 	 * @return string
 	 */
 	public static function getPath($id) {
diff --git a/lib/private/files/view.php b/lib/private/files/view.php
index 1639f765f69..e7328500ffb 100644
--- a/lib/private/files/view.php
+++ b/lib/private/files/view.php
@@ -48,6 +48,7 @@ use OC\Files\Mount\MoveableMount;
 use OCP\Files\FileNameTooLongException;
 use OCP\Files\InvalidCharacterInPathException;
 use OCP\Files\InvalidPathException;
+use OCP\Files\NotFoundException;
 use OCP\Files\ReservedWordException;
 use OCP\Lock\ILockingProvider;
 use OCP\Lock\LockedException;
@@ -533,6 +534,7 @@ class View {
 	 * @param string $path
 	 * @param mixed $data
 	 * @return bool|mixed
+	 * @throws \Exception
 	 */
 	public function file_put_contents($path, $data) {
 		if (is_resource($data)) { //not having to deal with streams in file_put_contents makes life easier
@@ -989,12 +991,13 @@ class View {
 	 * @param array $hooks (optional)
 	 * @param mixed $extraParam (optional)
 	 * @return mixed
+	 * @throws \Exception
 	 *
 	 * This method takes requests for basic filesystem functions (e.g. reading & writing
 	 * files), processes hooks and proxies, sanitises paths, and finally passes them on to
 	 * \OC\Files\Storage\Storage for delegation to a storage backend for execution
 	 */
-	private function basicOperation($operation, $path, $hooks = array(), $extraParam = null) {
+	private function basicOperation($operation, $path, $hooks = [], $extraParam = null) {
 		$postFix = (substr($path, -1, 1) === '/') ? '/' : '';
 		$absolutePath = Filesystem::normalizePath($this->getAbsolutePath($path));
 		if (Filesystem::isValidPath($path)
@@ -1166,7 +1169,7 @@ class View {
 	 * @param boolean|string $includeMountPoints true to add mountpoint sizes,
 	 * 'ext' to add only ext storage mount point sizes. Defaults to true.
 	 * defaults to true
-	 * @return \OC\Files\FileInfo|false
+	 * @return \OC\Files\FileInfo|bool False if file does not exist
 	 */
 	public function getFileInfo($path, $includeMountPoints = true) {
 		$this->assertPathLength($path);
@@ -1563,7 +1566,8 @@ class View {
 	 * Note that the resulting path is not guarantied to be unique for the id, multiple paths can point to the same file
 	 *
 	 * @param int $id
-	 * @return string|null
+	 * @throws NotFoundException
+	 * @return string
 	 */
 	public function getPath($id) {
 		$id = (int)$id;
@@ -1588,9 +1592,13 @@ class View {
 				}
 			}
 		}
-		return null;
+		throw new NotFoundException(sprintf('File with id "%s" has not been found.', $id));
 	}
 
+	/**
+	 * @param string $path
+	 * @throws InvalidPathException
+	 */
 	private function assertPathLength($path) {
 		$maxLen = min(PHP_MAXPATHLEN, 4000);
 		// Check for the string length - performed using isset() instead of strlen()
diff --git a/lib/private/hook.php b/lib/private/hook.php
index faf5495b646..68621580b16 100644
--- a/lib/private/hook.php
+++ b/lib/private/hook.php
@@ -78,12 +78,12 @@ class OC_Hook{
 	 * @param string $signalName name of signal
 	 * @param mixed $params default: array() array with additional data
 	 * @return bool true if slots exists or false if not
-	 *
+	 * @throws \OC\ServerNotAvailableException
 	 * Emits a signal. To get data from the slot use references!
 	 *
 	 * TODO: write example
 	 */
-	static public function emit($signalClass, $signalName, $params = array()) {
+	static public function emit($signalClass, $signalName, $params = []) {
 
 		// Return false if no hook handlers are listening to this
 		// emitting class
diff --git a/tests/lib/files/view.php b/tests/lib/files/view.php
index c0845a5613c..a84b8badd5a 100644
--- a/tests/lib/files/view.php
+++ b/tests/lib/files/view.php
@@ -207,15 +207,31 @@ class View extends \Test\TestCase {
 		$rootView = new \OC\Files\View('');
 
 		$cachedData = $rootView->getFileInfo('/foo.txt');
+		/** @var int $id1 */
 		$id1 = $cachedData['fileid'];
 		$this->assertEquals('/foo.txt', $rootView->getPath($id1));
 
 		$cachedData = $rootView->getFileInfo('/substorage/foo.txt');
+		/** @var int $id2 */
 		$id2 = $cachedData['fileid'];
 		$this->assertEquals('/substorage/foo.txt', $rootView->getPath($id2));
 
 		$folderView = new \OC\Files\View('/substorage');
 		$this->assertEquals('/foo.txt', $folderView->getPath($id2));
+	}
+
+	/**
+	 * @expectedException \OCP\Files\NotFoundException
+	 */
+	function testGetPathNotExisting() {
+		$storage1 = $this->getTestStorage();
+		\OC\Files\Filesystem::mount($storage1, [], '/');
+
+		$rootView = new \OC\Files\View('');
+		$cachedData = $rootView->getFileInfo('/foo.txt');
+		/** @var int $id1 */
+		$id1 = $cachedData['fileid'];
+		$folderView = new \OC\Files\View('/substorage');
 		$this->assertNull($folderView->getPath($id1));
 	}