if we don't have a encrypted file key we can return a empty string right away

apps/encryption/lib/keymanager.php

@@ -394,17 +394,20 @@ class KeyManager {
 	public function getFileKey($path, $uid) {
 		$encryptedFileKey = $this->keyStorage->getFileKey($path, $this->fileKeyId, Encryption::ID);
 
+		if (empty($encryptedFileKey)) {
+			return '';
+		}
+
+		if ($this->util->isMasterKeyEnabled()) {
+			$uid = $this->getMasterKeyId();
+		}
+
 		if (is_null($uid)) {
 			$uid = $this->getPublicShareKeyId();
 			$shareKey = $this->getShareKey($path, $uid);
 			$privateKey = $this->keyStorage->getSystemUserKey($this->publicShareKeyId . '.privateKey', Encryption::ID);
 			$privateKey = $this->crypt->decryptPrivateKey($privateKey);
 		} else {
-
-			if ($this->util->isMasterKeyEnabled()) {
-				$uid = $this->getMasterKeyId();
-			}
-
 			$shareKey = $this->getShareKey($path, $uid);
 			$privateKey = $this->session->getPrivateKey();
 		}

apps/encryption/tests/lib/crypto/encryptalltest.php

@@ -153,6 +153,36 @@ class EncryptAllTest extends TestCase {
 
 	}
 
+	public function testEncryptAllWithMasterKey() {
+		/** @var EncryptAll  | \PHPUnit_Framework_MockObject_MockObject  $encryptAll */
+		$encryptAll = $this->getMockBuilder('OCA\Encryption\Crypto\EncryptAll')
+			->setConstructorArgs(
+				[
+					$this->setupUser,
+					$this->userManager,
+					$this->view,
+					$this->keyManager,
+					$this->util,
+					$this->config,
+					$this->mailer,
+					$this->l,
+					$this->questionHelper,
+					$this->secureRandom
+				]
+			)
+			->setMethods(['createKeyPairs', 'encryptAllUsersFiles', 'outputPasswords'])
+			->getMock();
+
+		$this->util->expects($this->any())->method('isMasterKeyEnabled')->willReturn(true);
+		$encryptAll->expects($this->never())->method('createKeyPairs');
+		$this->keyManager->expects($this->once())->method('validateMasterKey');
+		$encryptAll->expects($this->at(0))->method('encryptAllUsersFiles')->with();
+		$encryptAll->expects($this->never())->method('outputPasswords');
+
+		$encryptAll->encryptAll($this->inputInterface, $this->outputInterface);
+
+	}
+
 	public function testCreateKeyPairs() {
 		/** @var EncryptAll  | \PHPUnit_Framework_MockObject_MockObject  $encryptAll */
 		$encryptAll = $this->getMockBuilder('OCA\Encryption\Crypto\EncryptAll')