nextcloud / server

lib/private/legacy/util.php

Indentation +1461 added lines, -1461 removed lines

@@ -67,1471 +67,1471 @@
 use OC\AppFramework\Http\Request;
 
 class OC_Util {
-	public static $scripts = array();
-	public static $styles = array();
-	public static $headers = array();
-	private static $rootMounted = false;
-	private static $fsSetup = false;
-
-	/** @var array Local cache of version.php */
-	private static $versionCache = null;
-
-	protected static function getAppManager() {
-		return \OC::$server->getAppManager();
-	}
-
-	private static function initLocalStorageRootFS() {
-		// mount local file backend as root
-		$configDataDirectory = \OC::$server->getSystemConfig()->getValue("datadirectory", OC::$SERVERROOT . "/data");
-		//first set up the local "root" storage
-		\OC\Files\Filesystem::initMountManager();
-		if (!self::$rootMounted) {
-			\OC\Files\Filesystem::mount('\OC\Files\Storage\Local', array('datadir' => $configDataDirectory), '/');
-			self::$rootMounted = true;
-		}
-	}
-
-	/**
-	 * mounting an object storage as the root fs will in essence remove the
-	 * necessity of a data folder being present.
-	 * TODO make home storage aware of this and use the object storage instead of local disk access
-	 *
-	 * @param array $config containing 'class' and optional 'arguments'
-	 * @suppress PhanDeprecatedFunction
-	 */
-	private static function initObjectStoreRootFS($config) {
-		// check misconfiguration
-		if (empty($config['class'])) {
-			\OCP\Util::writeLog('files', 'No class given for objectstore', ILogger::ERROR);
-		}
-		if (!isset($config['arguments'])) {
-			$config['arguments'] = array();
-		}
-
-		// instantiate object store implementation
-		$name = $config['class'];
-		if (strpos($name, 'OCA\\') === 0 && substr_count($name, '\\') >= 2) {
-			$segments = explode('\\', $name);
-			OC_App::loadApp(strtolower($segments[1]));
-		}
-		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
-		// mount with plain / root object store implementation
-		$config['class'] = '\OC\Files\ObjectStore\ObjectStoreStorage';
-
-		// mount object storage as root
-		\OC\Files\Filesystem::initMountManager();
-		if (!self::$rootMounted) {
-			\OC\Files\Filesystem::mount($config['class'], $config['arguments'], '/');
-			self::$rootMounted = true;
-		}
-	}
-
-	/**
-	 * mounting an object storage as the root fs will in essence remove the
-	 * necessity of a data folder being present.
-	 *
-	 * @param array $config containing 'class' and optional 'arguments'
-	 * @suppress PhanDeprecatedFunction
-	 */
-	private static function initObjectStoreMultibucketRootFS($config) {
-		// check misconfiguration
-		if (empty($config['class'])) {
-			\OCP\Util::writeLog('files', 'No class given for objectstore', ILogger::ERROR);
-		}
-		if (!isset($config['arguments'])) {
-			$config['arguments'] = array();
-		}
-
-		// instantiate object store implementation
-		$name = $config['class'];
-		if (strpos($name, 'OCA\\') === 0 && substr_count($name, '\\') >= 2) {
-			$segments = explode('\\', $name);
-			OC_App::loadApp(strtolower($segments[1]));
-		}
-
-		if (!isset($config['arguments']['bucket'])) {
-			$config['arguments']['bucket'] = '';
-		}
-		// put the root FS always in first bucket for multibucket configuration
-		$config['arguments']['bucket'] .= '0';
-
-		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
-		// mount with plain / root object store implementation
-		$config['class'] = '\OC\Files\ObjectStore\ObjectStoreStorage';
-
-		// mount object storage as root
-		\OC\Files\Filesystem::initMountManager();
-		if (!self::$rootMounted) {
-			\OC\Files\Filesystem::mount($config['class'], $config['arguments'], '/');
-			self::$rootMounted = true;
-		}
-	}
-
-	/**
-	 * Can be set up
-	 *
-	 * @param string $user
-	 * @return boolean
-	 * @description configure the initial filesystem based on the configuration
-	 * @suppress PhanDeprecatedFunction
-	 * @suppress PhanAccessMethodInternal
-	 */
-	public static function setupFS($user = '') {
-		//setting up the filesystem twice can only lead to trouble
-		if (self::$fsSetup) {
-			return false;
-		}
-
-		\OC::$server->getEventLogger()->start('setup_fs', 'Setup filesystem');
-
-		// If we are not forced to load a specific user we load the one that is logged in
-		if ($user === null) {
-			$user = '';
-		} else if ($user == "" && \OC::$server->getUserSession()->isLoggedIn()) {
-			$user = OC_User::getUser();
-		}
-
-		// load all filesystem apps before, so no setup-hook gets lost
-		OC_App::loadApps(array('filesystem'));
-
-		// the filesystem will finish when $user is not empty,
-		// mark fs setup here to avoid doing the setup from loading
-		// OC_Filesystem
-		if ($user != '') {
-			self::$fsSetup = true;
-		}
-
-		\OC\Files\Filesystem::initMountManager();
-
-		\OC\Files\Filesystem::logWarningWhenAddingStorageWrapper(false);
-		\OC\Files\Filesystem::addStorageWrapper('mount_options', function ($mountPoint, \OCP\Files\Storage $storage, \OCP\Files\Mount\IMountPoint $mount) {
-			if ($storage->instanceOfStorage('\OC\Files\Storage\Common')) {
-				/** @var \OC\Files\Storage\Common $storage */
-				$storage->setMountOptions($mount->getOptions());
-			}
-			return $storage;
-		});
-
-		\OC\Files\Filesystem::addStorageWrapper('enable_sharing', function ($mountPoint, \OCP\Files\Storage\IStorage $storage, \OCP\Files\Mount\IMountPoint $mount) {
-			if (!$mount->getOption('enable_sharing', true)) {
-				return new \OC\Files\Storage\Wrapper\PermissionsMask([
-					'storage' => $storage,
-					'mask' => \OCP\Constants::PERMISSION_ALL - \OCP\Constants::PERMISSION_SHARE
-				]);
-			}
-			return $storage;
-		});
-
-		// install storage availability wrapper, before most other wrappers
-		\OC\Files\Filesystem::addStorageWrapper('oc_availability', function ($mountPoint, \OCP\Files\Storage\IStorage $storage) {
-			if (!$storage->instanceOfStorage('\OCA\Files_Sharing\SharedStorage') && !$storage->isLocal()) {
-				return new \OC\Files\Storage\Wrapper\Availability(['storage' => $storage]);
-			}
-			return $storage;
-		});
-
-		\OC\Files\Filesystem::addStorageWrapper('oc_encoding', function ($mountPoint, \OCP\Files\Storage $storage, \OCP\Files\Mount\IMountPoint $mount) {
-			if ($mount->getOption('encoding_compatibility', false) && !$storage->instanceOfStorage('\OCA\Files_Sharing\SharedStorage') && !$storage->isLocal()) {
-				return new \OC\Files\Storage\Wrapper\Encoding(['storage' => $storage]);
-			}
-			return $storage;
-		});
-
-		\OC\Files\Filesystem::addStorageWrapper('oc_quota', function ($mountPoint, $storage) {
-			// set up quota for home storages, even for other users
-			// which can happen when using sharing
-
-			/**
-			 * @var \OC\Files\Storage\Storage $storage
-			 */
-			if ($storage->instanceOfStorage('\OC\Files\Storage\Home')
-				|| $storage->instanceOfStorage('\OC\Files\ObjectStore\HomeObjectStoreStorage')
-			) {
-				/** @var \OC\Files\Storage\Home $storage */
-				if (is_object($storage->getUser())) {
-					$user = $storage->getUser()->getUID();
-					$quota = OC_Util::getUserQuota($user);
-					if ($quota !== \OCP\Files\FileInfo::SPACE_UNLIMITED) {
-						return new \OC\Files\Storage\Wrapper\Quota(array('storage' => $storage, 'quota' => $quota, 'root' => 'files'));
-					}
-				}
-			}
-
-			return $storage;
-		});
-
-		\OC\Files\Filesystem::addStorageWrapper('readonly', function ($mountPoint, \OCP\Files\Storage\IStorage $storage, \OCP\Files\Mount\IMountPoint $mount) {
-			/*
+    public static $scripts = array();
+    public static $styles = array();
+    public static $headers = array();
+    private static $rootMounted = false;
+    private static $fsSetup = false;
+
+    /** @var array Local cache of version.php */
+    private static $versionCache = null;
+
+    protected static function getAppManager() {
+        return \OC::$server->getAppManager();
+    }
+
+    private static function initLocalStorageRootFS() {
+        // mount local file backend as root
+        $configDataDirectory = \OC::$server->getSystemConfig()->getValue("datadirectory", OC::$SERVERROOT . "/data");
+        //first set up the local "root" storage
+        \OC\Files\Filesystem::initMountManager();
+        if (!self::$rootMounted) {
+            \OC\Files\Filesystem::mount('\OC\Files\Storage\Local', array('datadir' => $configDataDirectory), '/');
+            self::$rootMounted = true;
+        }
+    }
+
+    /**
+     * mounting an object storage as the root fs will in essence remove the
+     * necessity of a data folder being present.
+     * TODO make home storage aware of this and use the object storage instead of local disk access
+     *
+     * @param array $config containing 'class' and optional 'arguments'
+     * @suppress PhanDeprecatedFunction
+     */
+    private static function initObjectStoreRootFS($config) {
+        // check misconfiguration
+        if (empty($config['class'])) {
+            \OCP\Util::writeLog('files', 'No class given for objectstore', ILogger::ERROR);
+        }
+        if (!isset($config['arguments'])) {
+            $config['arguments'] = array();
+        }
+
+        // instantiate object store implementation
+        $name = $config['class'];
+        if (strpos($name, 'OCA\\') === 0 && substr_count($name, '\\') >= 2) {
+            $segments = explode('\\', $name);
+            OC_App::loadApp(strtolower($segments[1]));
+        }
+        $config['arguments']['objectstore'] = new $config['class']($config['arguments']);
+        // mount with plain / root object store implementation
+        $config['class'] = '\OC\Files\ObjectStore\ObjectStoreStorage';
+
+        // mount object storage as root
+        \OC\Files\Filesystem::initMountManager();
+        if (!self::$rootMounted) {
+            \OC\Files\Filesystem::mount($config['class'], $config['arguments'], '/');
+            self::$rootMounted = true;
+        }
+    }
+
+    /**
+     * mounting an object storage as the root fs will in essence remove the
+     * necessity of a data folder being present.
+     *
+     * @param array $config containing 'class' and optional 'arguments'
+     * @suppress PhanDeprecatedFunction
+     */
+    private static function initObjectStoreMultibucketRootFS($config) {
+        // check misconfiguration
+        if (empty($config['class'])) {
+            \OCP\Util::writeLog('files', 'No class given for objectstore', ILogger::ERROR);
+        }
+        if (!isset($config['arguments'])) {
+            $config['arguments'] = array();
+        }
+
+        // instantiate object store implementation
+        $name = $config['class'];
+        if (strpos($name, 'OCA\\') === 0 && substr_count($name, '\\') >= 2) {
+            $segments = explode('\\', $name);
+            OC_App::loadApp(strtolower($segments[1]));
+        }
+
+        if (!isset($config['arguments']['bucket'])) {
+            $config['arguments']['bucket'] = '';
+        }
+        // put the root FS always in first bucket for multibucket configuration
+        $config['arguments']['bucket'] .= '0';
+
+        $config['arguments']['objectstore'] = new $config['class']($config['arguments']);
+        // mount with plain / root object store implementation
+        $config['class'] = '\OC\Files\ObjectStore\ObjectStoreStorage';
+
+        // mount object storage as root
+        \OC\Files\Filesystem::initMountManager();
+        if (!self::$rootMounted) {
+            \OC\Files\Filesystem::mount($config['class'], $config['arguments'], '/');
+            self::$rootMounted = true;
+        }
+    }
+
+    /**
+     * Can be set up
+     *
+     * @param string $user
+     * @return boolean
+     * @description configure the initial filesystem based on the configuration
+     * @suppress PhanDeprecatedFunction
+     * @suppress PhanAccessMethodInternal
+     */
+    public static function setupFS($user = '') {
+        //setting up the filesystem twice can only lead to trouble
+        if (self::$fsSetup) {
+            return false;
+        }
+
+        \OC::$server->getEventLogger()->start('setup_fs', 'Setup filesystem');
+
+        // If we are not forced to load a specific user we load the one that is logged in
+        if ($user === null) {
+            $user = '';
+        } else if ($user == "" && \OC::$server->getUserSession()->isLoggedIn()) {
+            $user = OC_User::getUser();
+        }
+
+        // load all filesystem apps before, so no setup-hook gets lost
+        OC_App::loadApps(array('filesystem'));
+
+        // the filesystem will finish when $user is not empty,
+        // mark fs setup here to avoid doing the setup from loading
+        // OC_Filesystem
+        if ($user != '') {
+            self::$fsSetup = true;
+        }
+
+        \OC\Files\Filesystem::initMountManager();
+
+        \OC\Files\Filesystem::logWarningWhenAddingStorageWrapper(false);
+        \OC\Files\Filesystem::addStorageWrapper('mount_options', function ($mountPoint, \OCP\Files\Storage $storage, \OCP\Files\Mount\IMountPoint $mount) {
+            if ($storage->instanceOfStorage('\OC\Files\Storage\Common')) {
+                /** @var \OC\Files\Storage\Common $storage */
+                $storage->setMountOptions($mount->getOptions());
+            }
+            return $storage;
+        });
+
+        \OC\Files\Filesystem::addStorageWrapper('enable_sharing', function ($mountPoint, \OCP\Files\Storage\IStorage $storage, \OCP\Files\Mount\IMountPoint $mount) {
+            if (!$mount->getOption('enable_sharing', true)) {
+                return new \OC\Files\Storage\Wrapper\PermissionsMask([
+                    'storage' => $storage,
+                    'mask' => \OCP\Constants::PERMISSION_ALL - \OCP\Constants::PERMISSION_SHARE
+                ]);
+            }
+            return $storage;
+        });
+
+        // install storage availability wrapper, before most other wrappers
+        \OC\Files\Filesystem::addStorageWrapper('oc_availability', function ($mountPoint, \OCP\Files\Storage\IStorage $storage) {
+            if (!$storage->instanceOfStorage('\OCA\Files_Sharing\SharedStorage') && !$storage->isLocal()) {
+                return new \OC\Files\Storage\Wrapper\Availability(['storage' => $storage]);
+            }
+            return $storage;
+        });
+
+        \OC\Files\Filesystem::addStorageWrapper('oc_encoding', function ($mountPoint, \OCP\Files\Storage $storage, \OCP\Files\Mount\IMountPoint $mount) {
+            if ($mount->getOption('encoding_compatibility', false) && !$storage->instanceOfStorage('\OCA\Files_Sharing\SharedStorage') && !$storage->isLocal()) {
+                return new \OC\Files\Storage\Wrapper\Encoding(['storage' => $storage]);
+            }
+            return $storage;
+        });
+
+        \OC\Files\Filesystem::addStorageWrapper('oc_quota', function ($mountPoint, $storage) {
+            // set up quota for home storages, even for other users
+            // which can happen when using sharing
+
+            /**
+             * @var \OC\Files\Storage\Storage $storage
+             */
+            if ($storage->instanceOfStorage('\OC\Files\Storage\Home')
+                || $storage->instanceOfStorage('\OC\Files\ObjectStore\HomeObjectStoreStorage')
+            ) {
+                /** @var \OC\Files\Storage\Home $storage */
+                if (is_object($storage->getUser())) {
+                    $user = $storage->getUser()->getUID();
+                    $quota = OC_Util::getUserQuota($user);
+                    if ($quota !== \OCP\Files\FileInfo::SPACE_UNLIMITED) {
+                        return new \OC\Files\Storage\Wrapper\Quota(array('storage' => $storage, 'quota' => $quota, 'root' => 'files'));
+                    }
+                }
+            }
+
+            return $storage;
+        });
+
+        \OC\Files\Filesystem::addStorageWrapper('readonly', function ($mountPoint, \OCP\Files\Storage\IStorage $storage, \OCP\Files\Mount\IMountPoint $mount) {
+            /*
 			 * Do not allow any operations that modify the storage
 			 */
-			if ($mount->getOption('readonly', false)) {
-				return new \OC\Files\Storage\Wrapper\PermissionsMask([
-					'storage' => $storage,
-					'mask' => \OCP\Constants::PERMISSION_ALL & ~(
-						\OCP\Constants::PERMISSION_UPDATE |
-						\OCP\Constants::PERMISSION_CREATE |
-						\OCP\Constants::PERMISSION_DELETE
-					),
-				]);
-			}
-			return $storage;
-		});
-
-		OC_Hook::emit('OC_Filesystem', 'preSetup', array('user' => $user));
-		\OC\Files\Filesystem::logWarningWhenAddingStorageWrapper(true);
-
-		//check if we are using an object storage
-		$objectStore = \OC::$server->getSystemConfig()->getValue('objectstore', null);
-		$objectStoreMultibucket = \OC::$server->getSystemConfig()->getValue('objectstore_multibucket', null);
-
-		// use the same order as in ObjectHomeMountProvider
-		if (isset($objectStoreMultibucket)) {
-			self::initObjectStoreMultibucketRootFS($objectStoreMultibucket);
-		} elseif (isset($objectStore)) {
-			self::initObjectStoreRootFS($objectStore);
-		} else {
-			self::initLocalStorageRootFS();
-		}
-
-		if ($user != '' && !\OC::$server->getUserManager()->userExists($user)) {
-			\OC::$server->getEventLogger()->end('setup_fs');
-			return false;
-		}
-
-		//if we aren't logged in, there is no use to set up the filesystem
-		if ($user != "") {
-
-			$userDir = '/' . $user . '/files';
-
-			//jail the user into his "home" directory
-			\OC\Files\Filesystem::init($user, $userDir);
-
-			OC_Hook::emit('OC_Filesystem', 'setup', array('user' => $user, 'user_dir' => $userDir));
-		}
-		\OC::$server->getEventLogger()->end('setup_fs');
-		return true;
-	}
-
-	/**
-	 * check if a password is required for each public link
-	 *
-	 * @return boolean
-	 * @suppress PhanDeprecatedFunction
-	 */
-	public static function isPublicLinkPasswordRequired() {
-		$enforcePassword = \OC::$server->getConfig()->getAppValue('core', 'shareapi_enforce_links_password', 'no');
-		return $enforcePassword === 'yes';
-	}
-
-	/**
-	 * check if sharing is disabled for the current user
-	 * @param IConfig $config
-	 * @param IGroupManager $groupManager
-	 * @param IUser|null $user
-	 * @return bool
-	 */
-	public static function isSharingDisabledForUser(IConfig $config, IGroupManager $groupManager, $user) {
-		if ($config->getAppValue('core', 'shareapi_exclude_groups', 'no') === 'yes') {
-			$groupsList = $config->getAppValue('core', 'shareapi_exclude_groups_list', '');
-			$excludedGroups = json_decode($groupsList);
-			if (is_null($excludedGroups)) {
-				$excludedGroups = explode(',', $groupsList);
-				$newValue = json_encode($excludedGroups);
-				$config->setAppValue('core', 'shareapi_exclude_groups_list', $newValue);
-			}
-			$usersGroups = $groupManager->getUserGroupIds($user);
-			if (!empty($usersGroups)) {
-				$remainingGroups = array_diff($usersGroups, $excludedGroups);
-				// if the user is only in groups which are disabled for sharing then
-				// sharing is also disabled for the user
-				if (empty($remainingGroups)) {
-					return true;
-				}
-			}
-		}
-		return false;
-	}
-
-	/**
-	 * check if share API enforces a default expire date
-	 *
-	 * @return boolean
-	 * @suppress PhanDeprecatedFunction
-	 */
-	public static function isDefaultExpireDateEnforced() {
-		$isDefaultExpireDateEnabled = \OC::$server->getConfig()->getAppValue('core', 'shareapi_default_expire_date', 'no');
-		$enforceDefaultExpireDate = false;
-		if ($isDefaultExpireDateEnabled === 'yes') {
-			$value = \OC::$server->getConfig()->getAppValue('core', 'shareapi_enforce_expire_date', 'no');
-			$enforceDefaultExpireDate = $value === 'yes';
-		}
-
-		return $enforceDefaultExpireDate;
-	}
-
-	/**
-	 * Get the quota of a user
-	 *
-	 * @param string $userId
-	 * @return float Quota bytes
-	 */
-	public static function getUserQuota($userId) {
-		$user = \OC::$server->getUserManager()->get($userId);
-		if (is_null($user)) {
-			return \OCP\Files\FileInfo::SPACE_UNLIMITED;
-		}
-		$userQuota = $user->getQuota();
-		if($userQuota === 'none') {
-			return \OCP\Files\FileInfo::SPACE_UNLIMITED;
-		}
-		return OC_Helper::computerFileSize($userQuota);
-	}
-
-	/**
-	 * copies the skeleton to the users /files
-	 *
-	 * @param String $userId
-	 * @param \OCP\Files\Folder $userDirectory
-	 * @throws \RuntimeException
-	 * @suppress PhanDeprecatedFunction
-	 */
-	public static function copySkeleton($userId, \OCP\Files\Folder $userDirectory) {
-
-		$plainSkeletonDirectory = \OC::$server->getConfig()->getSystemValue('skeletondirectory', \OC::$SERVERROOT . '/core/skeleton');
-		$userLang = \OC::$server->getL10NFactory()->findLanguage();
-		$skeletonDirectory = str_replace('{lang}', $userLang, $plainSkeletonDirectory);
-
-		if (!file_exists($skeletonDirectory)) {
-			$dialectStart = strpos($userLang, '_');
-			if ($dialectStart !== false) {
-				$skeletonDirectory = str_replace('{lang}', substr($userLang, 0, $dialectStart), $plainSkeletonDirectory);
-			}
-			if ($dialectStart === false || !file_exists($skeletonDirectory)) {
-				$skeletonDirectory = str_replace('{lang}', 'default', $plainSkeletonDirectory);
-			}
-			if (!file_exists($skeletonDirectory)) {
-				$skeletonDirectory = '';
-			}
-		}
-
-		$instanceId = \OC::$server->getConfig()->getSystemValue('instanceid', '');
-
-		if ($instanceId === null) {
-			throw new \RuntimeException('no instance id!');
-		}
-		$appdata = 'appdata_' . $instanceId;
-		if ($userId === $appdata) {
-			throw new \RuntimeException('username is reserved name: ' . $appdata);
-		}
-
-		if (!empty($skeletonDirectory)) {
-			\OCP\Util::writeLog(
-				'files_skeleton',
-				'copying skeleton for '.$userId.' from '.$skeletonDirectory.' to '.$userDirectory->getFullPath('/'),
-				ILogger::DEBUG
-			);
-			self::copyr($skeletonDirectory, $userDirectory);
-			// update the file cache
-			$userDirectory->getStorage()->getScanner()->scan('', \OC\Files\Cache\Scanner::SCAN_RECURSIVE);
-		}
-	}
-
-	/**
-	 * copies a directory recursively by using streams
-	 *
-	 * @param string $source
-	 * @param \OCP\Files\Folder $target
-	 * @return void
-	 */
-	public static function copyr($source, \OCP\Files\Folder $target) {
-		$logger = \OC::$server->getLogger();
-
-		// Verify if folder exists
-		$dir = opendir($source);
-		if($dir === false) {
-			$logger->error(sprintf('Could not opendir "%s"', $source), ['app' => 'core']);
-			return;
-		}
-
-		// Copy the files
-		while (false !== ($file = readdir($dir))) {
-			if (!\OC\Files\Filesystem::isIgnoredDir($file)) {
-				if (is_dir($source . '/' . $file)) {
-					$child = $target->newFolder($file);
-					self::copyr($source . '/' . $file, $child);
-				} else {
-					$child = $target->newFile($file);
-					$sourceStream = fopen($source . '/' . $file, 'r');
-					if($sourceStream === false) {
-						$logger->error(sprintf('Could not fopen "%s"', $source . '/' . $file), ['app' => 'core']);
-						closedir($dir);
-						return;
-					}
-					stream_copy_to_stream($sourceStream, $child->fopen('w'));
-				}
-			}
-		}
-		closedir($dir);
-	}
-
-	/**
-	 * @return void
-	 * @suppress PhanUndeclaredMethod
-	 */
-	public static function tearDownFS() {
-		\OC\Files\Filesystem::tearDown();
-		\OC::$server->getRootFolder()->clearCache();
-		self::$fsSetup = false;
-		self::$rootMounted = false;
-	}
-
-	/**
-	 * get the current installed version of ownCloud
-	 *
-	 * @return array
-	 */
-	public static function getVersion() {
-		OC_Util::loadVersion();
-		return self::$versionCache['OC_Version'];
-	}
-
-	/**
-	 * get the current installed version string of ownCloud
-	 *
-	 * @return string
-	 */
-	public static function getVersionString() {
-		OC_Util::loadVersion();
-		return self::$versionCache['OC_VersionString'];
-	}
-
-	/**
-	 * @deprecated the value is of no use anymore
-	 * @return string
-	 */
-	public static function getEditionString() {
-		return '';
-	}
-
-	/**
-	 * @description get the update channel of the current installed of ownCloud.
-	 * @return string
-	 */
-	public static function getChannel() {
-		OC_Util::loadVersion();
-		return \OC::$server->getConfig()->getSystemValue('updater.release.channel', self::$versionCache['OC_Channel']);
-	}
-
-	/**
-	 * @description get the build number of the current installed of ownCloud.
-	 * @return string
-	 */
-	public static function getBuild() {
-		OC_Util::loadVersion();
-		return self::$versionCache['OC_Build'];
-	}
-
-	/**
-	 * @description load the version.php into the session as cache
-	 * @suppress PhanUndeclaredVariable
-	 */
-	private static function loadVersion() {
-		if (self::$versionCache !== null) {
-			return;
-		}
-
-		$timestamp = filemtime(OC::$SERVERROOT . '/version.php');
-		require OC::$SERVERROOT . '/version.php';
-		/** @var $timestamp int */
-		self::$versionCache['OC_Version_Timestamp'] = $timestamp;
-		/** @var $OC_Version string */
-		self::$versionCache['OC_Version'] = $OC_Version;
-		/** @var $OC_VersionString string */
-		self::$versionCache['OC_VersionString'] = $OC_VersionString;
-		/** @var $OC_Build string */
-		self::$versionCache['OC_Build'] = $OC_Build;
-
-		/** @var $OC_Channel string */
-		self::$versionCache['OC_Channel'] = $OC_Channel;
-	}
-
-	/**
-	 * generates a path for JS/CSS files. If no application is provided it will create the path for core.
-	 *
-	 * @param string $application application to get the files from
-	 * @param string $directory directory within this application (css, js, vendor, etc)
-	 * @param string $file the file inside of the above folder
-	 * @return string the path
-	 */
-	private static function generatePath($application, $directory, $file) {
-		if (is_null($file)) {
-			$file = $application;
-			$application = "";
-		}
-		if (!empty($application)) {
-			return "$application/$directory/$file";
-		} else {
-			return "$directory/$file";
-		}
-	}
-
-	/**
-	 * add a javascript file
-	 *
-	 * @param string $application application id
-	 * @param string|null $file filename
-	 * @param bool $prepend prepend the Script to the beginning of the list
-	 * @return void
-	 */
-	public static function addScript($application, $file = null, $prepend = false) {
-		$path = OC_Util::generatePath($application, 'js', $file);
-
-		// core js files need separate handling
-		if ($application !== 'core' && $file !== null) {
-			self::addTranslations ( $application );
-		}
-		self::addExternalResource($application, $prepend, $path, "script");
-	}
-
-	/**
-	 * add a javascript file from the vendor sub folder
-	 *
-	 * @param string $application application id
-	 * @param string|null $file filename
-	 * @param bool $prepend prepend the Script to the beginning of the list
-	 * @return void
-	 */
-	public static function addVendorScript($application, $file = null, $prepend = false) {
-		$path = OC_Util::generatePath($application, 'vendor', $file);
-		self::addExternalResource($application, $prepend, $path, "script");
-	}
-
-	/**
-	 * add a translation JS file
-	 *
-	 * @param string $application application id
-	 * @param string|null $languageCode language code, defaults to the current language
-	 * @param bool|null $prepend prepend the Script to the beginning of the list
-	 */
-	public static function addTranslations($application, $languageCode = null, $prepend = false) {
-		if (is_null($languageCode)) {
-			$languageCode = \OC::$server->getL10NFactory()->findLanguage($application);
-		}
-		if (!empty($application)) {
-			$path = "$application/l10n/$languageCode";
-		} else {
-			$path = "l10n/$languageCode";
-		}
-		self::addExternalResource($application, $prepend, $path, "script");
-	}
-
-	/**
-	 * add a css file
-	 *
-	 * @param string $application application id
-	 * @param string|null $file filename
-	 * @param bool $prepend prepend the Style to the beginning of the list
-	 * @return void
-	 */
-	public static function addStyle($application, $file = null, $prepend = false) {
-		$path = OC_Util::generatePath($application, 'css', $file);
-		self::addExternalResource($application, $prepend, $path, "style");
-	}
-
-	/**
-	 * add a css file from the vendor sub folder
-	 *
-	 * @param string $application application id
-	 * @param string|null $file filename
-	 * @param bool $prepend prepend the Style to the beginning of the list
-	 * @return void
-	 */
-	public static function addVendorStyle($application, $file = null, $prepend = false) {
-		$path = OC_Util::generatePath($application, 'vendor', $file);
-		self::addExternalResource($application, $prepend, $path, "style");
-	}
-
-	/**
-	 * add an external resource css/js file
-	 *
-	 * @param string $application application id
-	 * @param bool $prepend prepend the file to the beginning of the list
-	 * @param string $path
-	 * @param string $type (script or style)
-	 * @return void
-	 */
-	private static function addExternalResource($application, $prepend, $path, $type = "script") {
-
-		if ($type === "style") {
-			if (!in_array($path, self::$styles)) {
-				if ($prepend === true) {
-					array_unshift ( self::$styles, $path );
-				} else {
-					self::$styles[] = $path;
-				}
-			}
-		} elseif ($type === "script") {
-			if (!in_array($path, self::$scripts)) {
-				if ($prepend === true) {
-					array_unshift ( self::$scripts, $path );
-				} else {
-					self::$scripts [] = $path;
-				}
-			}
-		}
-	}
-
-	/**
-	 * Add a custom element to the header
-	 * If $text is null then the element will be written as empty element.
-	 * So use "" to get a closing tag.
-	 * @param string $tag tag name of the element
-	 * @param array $attributes array of attributes for the element
-	 * @param string $text the text content for the element
-	 * @param bool $prepend prepend the header to the beginning of the list
-	 */
-	public static function addHeader($tag, $attributes, $text = null, $prepend = false) {
-		$header = array(
-			'tag' => $tag,
-			'attributes' => $attributes,
-			'text' => $text
-		);
-		if ($prepend === true) {
-			array_unshift (self::$headers, $header);
-
-		} else {
-			self::$headers[] = $header;
-		}
-	}
-
-	/**
-	 * check if the current server configuration is suitable for ownCloud
-	 *
-	 * @param \OC\SystemConfig $config
-	 * @return array arrays with error messages and hints
-	 */
-	public static function checkServer(\OC\SystemConfig $config) {
-		$l = \OC::$server->getL10N('lib');
-		$errors = array();
-		$CONFIG_DATADIRECTORY = $config->getValue('datadirectory', OC::$SERVERROOT . '/data');
-
-		if (!self::needUpgrade($config) && $config->getValue('installed', false)) {
-			// this check needs to be done every time
-			$errors = self::checkDataDirectoryValidity($CONFIG_DATADIRECTORY);
-		}
-
-		// Assume that if checkServer() succeeded before in this session, then all is fine.
-		if (\OC::$server->getSession()->exists('checkServer_succeeded') && \OC::$server->getSession()->get('checkServer_succeeded')) {
-			return $errors;
-		}
-
-		$webServerRestart = false;
-		$setup = new \OC\Setup(
-			$config,
-			\OC::$server->getIniWrapper(),
-			\OC::$server->getL10N('lib'),
-			\OC::$server->query(\OCP\Defaults::class),
-			\OC::$server->getLogger(),
-			\OC::$server->getSecureRandom(),
-			\OC::$server->query(\OC\Installer::class)
-		);
-
-		$urlGenerator = \OC::$server->getURLGenerator();
-
-		$availableDatabases = $setup->getSupportedDatabases();
-		if (empty($availableDatabases)) {
-			$errors[] = array(
-				'error' => $l->t('No database drivers (sqlite, mysql, or postgresql) installed.'),
-				'hint' => '' //TODO: sane hint
-			);
-			$webServerRestart = true;
-		}
-
-		// Check if config folder is writable.
-		if(!OC_Helper::isReadOnlyConfigEnabled()) {
-			if (!is_writable(OC::$configDir) or !is_readable(OC::$configDir)) {
-				$errors[] = array(
-					'error' => $l->t('Cannot write into "config" directory'),
-					'hint' => $l->t('This can usually be fixed by giving the webserver write access to the config directory. See %s',
-						[ $urlGenerator->linkToDocs('admin-dir_permissions') ]) . '. '
-						. $l->t('Or, if you prefer to keep config.php file read only, set the option "config_is_read_only" to true in it. See %s',
-						[ $urlGenerator->linkToDocs('admin-config') ] )
-				);
-			}
-		}
-
-		// Check if there is a writable install folder.
-		if ($config->getValue('appstoreenabled', true)) {
-			if (OC_App::getInstallPath() === null
-				|| !is_writable(OC_App::getInstallPath())
-				|| !is_readable(OC_App::getInstallPath())
-			) {
-				$errors[] = array(
-					'error' => $l->t('Cannot write into "apps" directory'),
-					'hint' => $l->t('This can usually be fixed by giving the webserver write access to the apps directory'
-						. ' or disabling the appstore in the config file. See %s',
-						[$urlGenerator->linkToDocs('admin-dir_permissions')])
-				);
-			}
-		}
-		// Create root dir.
-		if ($config->getValue('installed', false)) {
-			if (!is_dir($CONFIG_DATADIRECTORY)) {
-				$success = @mkdir($CONFIG_DATADIRECTORY);
-				if ($success) {
-					$errors = array_merge($errors, self::checkDataDirectoryPermissions($CONFIG_DATADIRECTORY));
-				} else {
-					$errors[] = [
-						'error' => $l->t('Cannot create "data" directory'),
-						'hint' => $l->t('This can usually be fixed by giving the webserver write access to the root directory. See %s',
-							[$urlGenerator->linkToDocs('admin-dir_permissions')])
-					];
-				}
-			} else if (!is_writable($CONFIG_DATADIRECTORY) or !is_readable($CONFIG_DATADIRECTORY)) {
-				//common hint for all file permissions error messages
-				$permissionsHint = $l->t('Permissions can usually be fixed by giving the webserver write access to the root directory. See %s.',
-					[$urlGenerator->linkToDocs('admin-dir_permissions')]);
-				$errors[] = [
-					'error' => 'Your data directory is not writable',
-					'hint' => $permissionsHint
-				];
-			} else {
-				$errors = array_merge($errors, self::checkDataDirectoryPermissions($CONFIG_DATADIRECTORY));
-			}
-		}
-
-		if (!OC_Util::isSetLocaleWorking()) {
-			$errors[] = array(
-				'error' => $l->t('Setting locale to %s failed',
-					array('en_US.UTF-8/fr_FR.UTF-8/es_ES.UTF-8/de_DE.UTF-8/ru_RU.UTF-8/'
-						. 'pt_BR.UTF-8/it_IT.UTF-8/ja_JP.UTF-8/zh_CN.UTF-8')),
-				'hint' => $l->t('Please install one of these locales on your system and restart your webserver.')
-			);
-		}
-
-		// Contains the dependencies that should be checked against
-		// classes = class_exists
-		// functions = function_exists
-		// defined = defined
-		// ini = ini_get
-		// If the dependency is not found the missing module name is shown to the EndUser
-		// When adding new checks always verify that they pass on Travis as well
-		// for ini settings, see https://github.com/owncloud/administration/blob/master/travis-ci/custom.ini
-		$dependencies = array(
-			'classes' => array(
-				'ZipArchive' => 'zip',
-				'DOMDocument' => 'dom',
-				'XMLWriter' => 'XMLWriter',
-				'XMLReader' => 'XMLReader',
-			),
-			'functions' => [
-				'xml_parser_create' => 'libxml',
-				'mb_strcut' => 'mb multibyte',
-				'ctype_digit' => 'ctype',
-				'json_encode' => 'JSON',
-				'gd_info' => 'GD',
-				'gzencode' => 'zlib',
-				'iconv' => 'iconv',
-				'simplexml_load_string' => 'SimpleXML',
-				'hash' => 'HASH Message Digest Framework',
-				'curl_init' => 'cURL',
-				'openssl_verify' => 'OpenSSL',
-			],
-			'defined' => array(
-				'PDO::ATTR_DRIVER_NAME' => 'PDO'
-			),
-			'ini' => [
-				'default_charset' => 'UTF-8',
-			],
-		);
-		$missingDependencies = array();
-		$invalidIniSettings = [];
-		$moduleHint = $l->t('Please ask your server administrator to install the module.');
-
-		/**
-		 * FIXME: The dependency check does not work properly on HHVM on the moment
-		 *        and prevents installation. Once HHVM is more compatible with our
-		 *        approach to check for these values we should re-enable those
-		 *        checks.
-		 */
-		$iniWrapper = \OC::$server->getIniWrapper();
-		if (!self::runningOnHhvm()) {
-			foreach ($dependencies['classes'] as $class => $module) {
-				if (!class_exists($class)) {
-					$missingDependencies[] = $module;
-				}
-			}
-			foreach ($dependencies['functions'] as $function => $module) {
-				if (!function_exists($function)) {
-					$missingDependencies[] = $module;
-				}
-			}
-			foreach ($dependencies['defined'] as $defined => $module) {
-				if (!defined($defined)) {
-					$missingDependencies[] = $module;
-				}
-			}
-			foreach ($dependencies['ini'] as $setting => $expected) {
-				if (is_bool($expected)) {
-					if ($iniWrapper->getBool($setting) !== $expected) {
-						$invalidIniSettings[] = [$setting, $expected];
-					}
-				}
-				if (is_int($expected)) {
-					if ($iniWrapper->getNumeric($setting) !== $expected) {
-						$invalidIniSettings[] = [$setting, $expected];
-					}
-				}
-				if (is_string($expected)) {
-					if (strtolower($iniWrapper->getString($setting)) !== strtolower($expected)) {
-						$invalidIniSettings[] = [$setting, $expected];
-					}
-				}
-			}
-		}
-
-		foreach($missingDependencies as $missingDependency) {
-			$errors[] = array(
-				'error' => $l->t('PHP module %s not installed.', array($missingDependency)),
-				'hint' => $moduleHint
-			);
-			$webServerRestart = true;
-		}
-		foreach($invalidIniSettings as $setting) {
-			if(is_bool($setting[1])) {
-				$setting[1] = $setting[1] ? 'on' : 'off';
-			}
-			$errors[] = [
-				'error' => $l->t('PHP setting "%s" is not set to "%s".', [$setting[0], var_export($setting[1], true)]),
-				'hint' =>  $l->t('Adjusting this setting in php.ini will make Nextcloud run again')
-			];
-			$webServerRestart = true;
-		}
-
-		/**
-		 * The mbstring.func_overload check can only be performed if the mbstring
-		 * module is installed as it will return null if the checking setting is
-		 * not available and thus a check on the boolean value fails.
-		 *
-		 * TODO: Should probably be implemented in the above generic dependency
-		 *       check somehow in the long-term.
-		 */
-		if($iniWrapper->getBool('mbstring.func_overload') !== null &&
-			$iniWrapper->getBool('mbstring.func_overload') === true) {
-			$errors[] = array(
-				'error' => $l->t('mbstring.func_overload is set to "%s" instead of the expected value "0"', [$iniWrapper->getString('mbstring.func_overload')]),
-				'hint' => $l->t('To fix this issue set <code>mbstring.func_overload</code> to <code>0</code> in your php.ini')
-			);
-		}
-
-		if(function_exists('xml_parser_create') &&
-			LIBXML_LOADED_VERSION < 20700 ) {
-			$version = LIBXML_LOADED_VERSION;
-			$major = floor($version/10000);
-			$version -= ($major * 10000);
-			$minor = floor($version/100);
-			$version -= ($minor * 100);
-			$patch = $version;
-			$errors[] = array(
-				'error' => $l->t('libxml2 2.7.0 is at least required. Currently %s is installed.', [$major . '.' . $minor . '.' . $patch]),
-				'hint' => $l->t('To fix this issue update your libxml2 version and restart your web server.')
-			);
-		}
-
-		if (!self::isAnnotationsWorking()) {
-			$errors[] = array(
-				'error' => $l->t('PHP is apparently set up to strip inline doc blocks. This will make several core apps inaccessible.'),
-				'hint' => $l->t('This is probably caused by a cache/accelerator such as Zend OPcache or eAccelerator.')
-			);
-		}
-
-		if (!\OC::$CLI && $webServerRestart) {
-			$errors[] = array(
-				'error' => $l->t('PHP modules have been installed, but they are still listed as missing?'),
-				'hint' => $l->t('Please ask your server administrator to restart the web server.')
-			);
-		}
-
-		$errors = array_merge($errors, self::checkDatabaseVersion());
-
-		// Cache the result of this function
-		\OC::$server->getSession()->set('checkServer_succeeded', count($errors) == 0);
-
-		return $errors;
-	}
-
-	/**
-	 * Check the database version
-	 *
-	 * @return array errors array
-	 */
-	public static function checkDatabaseVersion() {
-		$l = \OC::$server->getL10N('lib');
-		$errors = array();
-		$dbType = \OC::$server->getSystemConfig()->getValue('dbtype', 'sqlite');
-		if ($dbType === 'pgsql') {
-			// check PostgreSQL version
-			try {
-				$result = \OC_DB::executeAudited('SHOW SERVER_VERSION');
-				$data = $result->fetchRow();
-				if (isset($data['server_version'])) {
-					$version = $data['server_version'];
-					if (version_compare($version, '9.0.0', '<')) {
-						$errors[] = array(
-							'error' => $l->t('PostgreSQL >= 9 required'),
-							'hint' => $l->t('Please upgrade your database version')
-						);
-					}
-				}
-			} catch (\Doctrine\DBAL\DBALException $e) {
-				$logger = \OC::$server->getLogger();
-				$logger->warning('Error occurred while checking PostgreSQL version, assuming >= 9');
-				$logger->logException($e);
-			}
-		}
-		return $errors;
-	}
-
-	/**
-	 * Check for correct file permissions of data directory
-	 *
-	 * @param string $dataDirectory
-	 * @return array arrays with error messages and hints
-	 */
-	public static function checkDataDirectoryPermissions($dataDirectory) {
-		if(\OC::$server->getConfig()->getSystemValue('check_data_directory_permissions', true) === false) {
-			return  [];
-		}
-		$l = \OC::$server->getL10N('lib');
-		$errors = [];
-		$permissionsModHint = $l->t('Please change the permissions to 0770 so that the directory'
-			. ' cannot be listed by other users.');
-		$perms = substr(decoct(@fileperms($dataDirectory)), -3);
-		if (substr($perms, -1) !== '0') {
-			chmod($dataDirectory, 0770);
-			clearstatcache();
-			$perms = substr(decoct(@fileperms($dataDirectory)), -3);
-			if ($perms[2] !== '0') {
-				$errors[] = [
-					'error' => $l->t('Your data directory is readable by other users'),
-					'hint' => $permissionsModHint
-				];
-			}
-		}
-		return $errors;
-	}
-
-	/**
-	 * Check that the data directory exists and is valid by
-	 * checking the existence of the ".ocdata" file.
-	 *
-	 * @param string $dataDirectory data directory path
-	 * @return array errors found
-	 */
-	public static function checkDataDirectoryValidity($dataDirectory) {
-		$l = \OC::$server->getL10N('lib');
-		$errors = [];
-		if ($dataDirectory[0] !== '/') {
-			$errors[] = [
-				'error' => $l->t('Your data directory must be an absolute path'),
-				'hint' => $l->t('Check the value of "datadirectory" in your configuration')
-			];
-		}
-		if (!file_exists($dataDirectory . '/.ocdata')) {
-			$errors[] = [
-				'error' => $l->t('Your data directory is invalid'),
-				'hint' => $l->t('Ensure there is a file called ".ocdata"' .
-					' in the root of the data directory.')
-			];
-		}
-		return $errors;
-	}
-
-	/**
-	 * Check if the user is logged in, redirects to home if not. With
-	 * redirect URL parameter to the request URI.
-	 *
-	 * @return void
-	 */
-	public static function checkLoggedIn() {
-		// Check if we are a user
-		if (!\OC::$server->getUserSession()->isLoggedIn()) {
-			header('Location: ' . \OC::$server->getURLGenerator()->linkToRoute(
-						'core.login.showLoginForm',
-						[
-							'redirect_url' => \OC::$server->getRequest()->getRequestUri(),
-						]
-					)
-			);
-			exit();
-		}
-		// Redirect to 2FA challenge selection if 2FA challenge was not solved yet
-		if (\OC::$server->getTwoFactorAuthManager()->needsSecondFactor(\OC::$server->getUserSession()->getUser())) {
-			header('Location: ' . \OC::$server->getURLGenerator()->linkToRoute('core.TwoFactorChallenge.selectChallenge'));
-			exit();
-		}
-	}
-
-	/**
-	 * Check if the user is a admin, redirects to home if not
-	 *
-	 * @return void
-	 */
-	public static function checkAdminUser() {
-		OC_Util::checkLoggedIn();
-		if (!OC_User::isAdminUser(OC_User::getUser())) {
-			header('Location: ' . \OCP\Util::linkToAbsolute('', 'index.php'));
-			exit();
-		}
-	}
-
-	/**
-	 * Check if the user is a subadmin, redirects to home if not
-	 *
-	 * @return null|boolean $groups where the current user is subadmin
-	 */
-	public static function checkSubAdminUser() {
-		OC_Util::checkLoggedIn();
-		$userObject = \OC::$server->getUserSession()->getUser();
-		$isSubAdmin = false;
-		if($userObject !== null) {
-			$isSubAdmin = \OC::$server->getGroupManager()->getSubAdmin()->isSubAdmin($userObject);
-		}
-
-		if (!$isSubAdmin) {
-			header('Location: ' . \OCP\Util::linkToAbsolute('', 'index.php'));
-			exit();
-		}
-		return true;
-	}
-
-	/**
-	 * Returns the URL of the default page
-	 * based on the system configuration and
-	 * the apps visible for the current user
-	 *
-	 * @return string URL
-	 * @suppress PhanDeprecatedFunction
-	 */
-	public static function getDefaultPageUrl() {
-		$urlGenerator = \OC::$server->getURLGenerator();
-		// Deny the redirect if the URL contains a @
-		// This prevents unvalidated redirects like ?redirect_url=:user@domain.com
-		if (isset($_REQUEST['redirect_url']) && strpos($_REQUEST['redirect_url'], '@') === false) {
-			$location = $urlGenerator->getAbsoluteURL(urldecode($_REQUEST['redirect_url']));
-		} else {
-			$defaultPage = \OC::$server->getConfig()->getAppValue('core', 'defaultpage');
-			if ($defaultPage) {
-				$location = $urlGenerator->getAbsoluteURL($defaultPage);
-			} else {
-				$appId = 'files';
-				$config = \OC::$server->getConfig();
-				$defaultApps = explode(',', $config->getSystemValue('defaultapp', 'files'));
-				// find the first app that is enabled for the current user
-				foreach ($defaultApps as $defaultApp) {
-					$defaultApp = OC_App::cleanAppId(strip_tags($defaultApp));
-					if (static::getAppManager()->isEnabledForUser($defaultApp)) {
-						$appId = $defaultApp;
-						break;
-					}
-				}
-
-				if($config->getSystemValue('htaccess.IgnoreFrontController', false) === true || getenv('front_controller_active') === 'true') {
-					$location = $urlGenerator->getAbsoluteURL('/apps/' . $appId . '/');
-				} else {
-					$location = $urlGenerator->getAbsoluteURL('/index.php/apps/' . $appId . '/');
-				}
-			}
-		}
-		return $location;
-	}
-
-	/**
-	 * Redirect to the user default page
-	 *
-	 * @return void
-	 */
-	public static function redirectToDefaultPage() {
-		$location = self::getDefaultPageUrl();
-		header('Location: ' . $location);
-		exit();
-	}
-
-	/**
-	 * get an id unique for this instance
-	 *
-	 * @return string
-	 */
-	public static function getInstanceId() {
-		$id = \OC::$server->getSystemConfig()->getValue('instanceid', null);
-		if (is_null($id)) {
-			// We need to guarantee at least one letter in instanceid so it can be used as the session_name
-			$id = 'oc' . \OC::$server->getSecureRandom()->generate(10, \OCP\Security\ISecureRandom::CHAR_LOWER.\OCP\Security\ISecureRandom::CHAR_DIGITS);
-			\OC::$server->getSystemConfig()->setValue('instanceid', $id);
-		}
-		return $id;
-	}
-
-	/**
-	 * Public function to sanitize HTML
-	 *
-	 * This function is used to sanitize HTML and should be applied on any
-	 * string or array of strings before displaying it on a web page.
-	 *
-	 * @param string|array $value
-	 * @return string|array an array of sanitized strings or a single sanitized string, depends on the input parameter.
-	 */
-	public static function sanitizeHTML($value) {
-		if (is_array($value)) {
-			$value = array_map(function($value) {
-				return self::sanitizeHTML($value);
-			}, $value);
-		} else {
-			// Specify encoding for PHP<5.4
-			$value = htmlspecialchars((string)$value, ENT_QUOTES, 'UTF-8');
-		}
-		return $value;
-	}
-
-	/**
-	 * Public function to encode url parameters
-	 *
-	 * This function is used to encode path to file before output.
-	 * Encoding is done according to RFC 3986 with one exception:
-	 * Character '/' is preserved as is.
-	 *
-	 * @param string $component part of URI to encode
-	 * @return string
-	 */
-	public static function encodePath($component) {
-		$encoded = rawurlencode($component);
-		$encoded = str_replace('%2F', '/', $encoded);
-		return $encoded;
-	}
-
-
-	public function createHtaccessTestFile(\OCP\IConfig $config) {
-		// php dev server does not support htaccess
-		if (php_sapi_name() === 'cli-server') {
-			return false;
-		}
-
-		// testdata
-		$fileName = '/htaccesstest.txt';
-		$testContent = 'This is used for testing whether htaccess is properly enabled to disallow access from the outside. This file can be safely removed.';
-
-		// creating a test file
-		$testFile = $config->getSystemValue('datadirectory', OC::$SERVERROOT . '/data') . '/' . $fileName;
-
-		if (file_exists($testFile)) {// already running this test, possible recursive call
-			return false;
-		}
-
-		$fp = @fopen($testFile, 'w');
-		if (!$fp) {
-			throw new OC\HintException('Can\'t create test file to check for working .htaccess file.',
-				'Make sure it is possible for the webserver to write to ' . $testFile);
-		}
-		fwrite($fp, $testContent);
-		fclose($fp);
-
-		return $testContent;
-	}
-
-	/**
-	 * Check if the .htaccess file is working
-	 * @param \OCP\IConfig $config
-	 * @return bool
-	 * @throws Exception
-	 * @throws \OC\HintException If the test file can't get written.
-	 */
-	public function isHtaccessWorking(\OCP\IConfig $config) {
-
-		if (\OC::$CLI || !$config->getSystemValue('check_for_working_htaccess', true)) {
-			return true;
-		}
-
-		$testContent = $this->createHtaccessTestFile($config);
-		if ($testContent === false) {
-			return false;
-		}
-
-		$fileName = '/htaccesstest.txt';
-		$testFile = $config->getSystemValue('datadirectory', OC::$SERVERROOT . '/data') . '/' . $fileName;
-
-		// accessing the file via http
-		$url = \OC::$server->getURLGenerator()->getAbsoluteURL(OC::$WEBROOT . '/data' . $fileName);
-		try {
-			$content = \OC::$server->getHTTPClientService()->newClient()->get($url)->getBody();
-		} catch (\Exception $e) {
-			$content = false;
-		}
-
-		// cleanup
-		@unlink($testFile);
-
-		/*
+            if ($mount->getOption('readonly', false)) {
+                return new \OC\Files\Storage\Wrapper\PermissionsMask([
+                    'storage' => $storage,
+                    'mask' => \OCP\Constants::PERMISSION_ALL & ~(
+                        \OCP\Constants::PERMISSION_UPDATE |
+                        \OCP\Constants::PERMISSION_CREATE |
+                        \OCP\Constants::PERMISSION_DELETE
+                    ),
+                ]);
+            }
+            return $storage;
+        });
+
+        OC_Hook::emit('OC_Filesystem', 'preSetup', array('user' => $user));
+        \OC\Files\Filesystem::logWarningWhenAddingStorageWrapper(true);
+
+        //check if we are using an object storage
+        $objectStore = \OC::$server->getSystemConfig()->getValue('objectstore', null);
+        $objectStoreMultibucket = \OC::$server->getSystemConfig()->getValue('objectstore_multibucket', null);
+
+        // use the same order as in ObjectHomeMountProvider
+        if (isset($objectStoreMultibucket)) {
+            self::initObjectStoreMultibucketRootFS($objectStoreMultibucket);
+        } elseif (isset($objectStore)) {
+            self::initObjectStoreRootFS($objectStore);
+        } else {
+            self::initLocalStorageRootFS();
+        }
+
+        if ($user != '' && !\OC::$server->getUserManager()->userExists($user)) {
+            \OC::$server->getEventLogger()->end('setup_fs');
+            return false;
+        }
+
+        //if we aren't logged in, there is no use to set up the filesystem
+        if ($user != "") {
+
+            $userDir = '/' . $user . '/files';
+
+            //jail the user into his "home" directory
+            \OC\Files\Filesystem::init($user, $userDir);
+
+            OC_Hook::emit('OC_Filesystem', 'setup', array('user' => $user, 'user_dir' => $userDir));
+        }
+        \OC::$server->getEventLogger()->end('setup_fs');
+        return true;
+    }
+
+    /**
+     * check if a password is required for each public link
+     *
+     * @return boolean
+     * @suppress PhanDeprecatedFunction
+     */
+    public static function isPublicLinkPasswordRequired() {
+        $enforcePassword = \OC::$server->getConfig()->getAppValue('core', 'shareapi_enforce_links_password', 'no');
+        return $enforcePassword === 'yes';
+    }
+
+    /**
+     * check if sharing is disabled for the current user
+     * @param IConfig $config
+     * @param IGroupManager $groupManager
+     * @param IUser|null $user
+     * @return bool
+     */
+    public static function isSharingDisabledForUser(IConfig $config, IGroupManager $groupManager, $user) {
+        if ($config->getAppValue('core', 'shareapi_exclude_groups', 'no') === 'yes') {
+            $groupsList = $config->getAppValue('core', 'shareapi_exclude_groups_list', '');
+            $excludedGroups = json_decode($groupsList);
+            if (is_null($excludedGroups)) {
+                $excludedGroups = explode(',', $groupsList);
+                $newValue = json_encode($excludedGroups);
+                $config->setAppValue('core', 'shareapi_exclude_groups_list', $newValue);
+            }
+            $usersGroups = $groupManager->getUserGroupIds($user);
+            if (!empty($usersGroups)) {
+                $remainingGroups = array_diff($usersGroups, $excludedGroups);
+                // if the user is only in groups which are disabled for sharing then
+                // sharing is also disabled for the user
+                if (empty($remainingGroups)) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    /**
+     * check if share API enforces a default expire date
+     *
+     * @return boolean
+     * @suppress PhanDeprecatedFunction
+     */
+    public static function isDefaultExpireDateEnforced() {
+        $isDefaultExpireDateEnabled = \OC::$server->getConfig()->getAppValue('core', 'shareapi_default_expire_date', 'no');
+        $enforceDefaultExpireDate = false;
+        if ($isDefaultExpireDateEnabled === 'yes') {
+            $value = \OC::$server->getConfig()->getAppValue('core', 'shareapi_enforce_expire_date', 'no');
+            $enforceDefaultExpireDate = $value === 'yes';
+        }
+
+        return $enforceDefaultExpireDate;
+    }
+
+    /**
+     * Get the quota of a user
+     *
+     * @param string $userId
+     * @return float Quota bytes
+     */
+    public static function getUserQuota($userId) {
+        $user = \OC::$server->getUserManager()->get($userId);
+        if (is_null($user)) {
+            return \OCP\Files\FileInfo::SPACE_UNLIMITED;
+        }
+        $userQuota = $user->getQuota();
+        if($userQuota === 'none') {
+            return \OCP\Files\FileInfo::SPACE_UNLIMITED;
+        }
+        return OC_Helper::computerFileSize($userQuota);
+    }
+
+    /**
+     * copies the skeleton to the users /files
+     *
+     * @param String $userId
+     * @param \OCP\Files\Folder $userDirectory
+     * @throws \RuntimeException
+     * @suppress PhanDeprecatedFunction
+     */
+    public static function copySkeleton($userId, \OCP\Files\Folder $userDirectory) {
+
+        $plainSkeletonDirectory = \OC::$server->getConfig()->getSystemValue('skeletondirectory', \OC::$SERVERROOT . '/core/skeleton');
+        $userLang = \OC::$server->getL10NFactory()->findLanguage();
+        $skeletonDirectory = str_replace('{lang}', $userLang, $plainSkeletonDirectory);
+
+        if (!file_exists($skeletonDirectory)) {
+            $dialectStart = strpos($userLang, '_');
+            if ($dialectStart !== false) {
+                $skeletonDirectory = str_replace('{lang}', substr($userLang, 0, $dialectStart), $plainSkeletonDirectory);
+            }
+            if ($dialectStart === false || !file_exists($skeletonDirectory)) {
+                $skeletonDirectory = str_replace('{lang}', 'default', $plainSkeletonDirectory);
+            }
+            if (!file_exists($skeletonDirectory)) {
+                $skeletonDirectory = '';
+            }
+        }
+
+        $instanceId = \OC::$server->getConfig()->getSystemValue('instanceid', '');
+
+        if ($instanceId === null) {
+            throw new \RuntimeException('no instance id!');
+        }
+        $appdata = 'appdata_' . $instanceId;
+        if ($userId === $appdata) {
+            throw new \RuntimeException('username is reserved name: ' . $appdata);
+        }
+
+        if (!empty($skeletonDirectory)) {
+            \OCP\Util::writeLog(
+                'files_skeleton',
+                'copying skeleton for '.$userId.' from '.$skeletonDirectory.' to '.$userDirectory->getFullPath('/'),
+                ILogger::DEBUG
+            );
+            self::copyr($skeletonDirectory, $userDirectory);
+            // update the file cache
+            $userDirectory->getStorage()->getScanner()->scan('', \OC\Files\Cache\Scanner::SCAN_RECURSIVE);
+        }
+    }
+
+    /**
+     * copies a directory recursively by using streams
+     *
+     * @param string $source
+     * @param \OCP\Files\Folder $target
+     * @return void
+     */
+    public static function copyr($source, \OCP\Files\Folder $target) {
+        $logger = \OC::$server->getLogger();
+
+        // Verify if folder exists
+        $dir = opendir($source);
+        if($dir === false) {
+            $logger->error(sprintf('Could not opendir "%s"', $source), ['app' => 'core']);
+            return;
+        }
+
+        // Copy the files
+        while (false !== ($file = readdir($dir))) {
+            if (!\OC\Files\Filesystem::isIgnoredDir($file)) {
+                if (is_dir($source . '/' . $file)) {
+                    $child = $target->newFolder($file);
+                    self::copyr($source . '/' . $file, $child);
+                } else {
+                    $child = $target->newFile($file);
+                    $sourceStream = fopen($source . '/' . $file, 'r');
+                    if($sourceStream === false) {
+                        $logger->error(sprintf('Could not fopen "%s"', $source . '/' . $file), ['app' => 'core']);
+                        closedir($dir);
+                        return;
+                    }
+                    stream_copy_to_stream($sourceStream, $child->fopen('w'));
+                }
+            }
+        }
+        closedir($dir);
+    }
+
+    /**
+     * @return void
+     * @suppress PhanUndeclaredMethod
+     */
+    public static function tearDownFS() {
+        \OC\Files\Filesystem::tearDown();
+        \OC::$server->getRootFolder()->clearCache();
+        self::$fsSetup = false;
+        self::$rootMounted = false;
+    }
+
+    /**
+     * get the current installed version of ownCloud
+     *
+     * @return array
+     */
+    public static function getVersion() {
+        OC_Util::loadVersion();
+        return self::$versionCache['OC_Version'];
+    }
+
+    /**
+     * get the current installed version string of ownCloud
+     *
+     * @return string
+     */
+    public static function getVersionString() {
+        OC_Util::loadVersion();
+        return self::$versionCache['OC_VersionString'];
+    }
+
+    /**
+     * @deprecated the value is of no use anymore
+     * @return string
+     */
+    public static function getEditionString() {
+        return '';
+    }
+
+    /**
+     * @description get the update channel of the current installed of ownCloud.
+     * @return string
+     */
+    public static function getChannel() {
+        OC_Util::loadVersion();
+        return \OC::$server->getConfig()->getSystemValue('updater.release.channel', self::$versionCache['OC_Channel']);
+    }
+
+    /**
+     * @description get the build number of the current installed of ownCloud.
+     * @return string
+     */
+    public static function getBuild() {
+        OC_Util::loadVersion();
+        return self::$versionCache['OC_Build'];
+    }
+
+    /**
+     * @description load the version.php into the session as cache
+     * @suppress PhanUndeclaredVariable
+     */
+    private static function loadVersion() {
+        if (self::$versionCache !== null) {
+            return;
+        }
+
+        $timestamp = filemtime(OC::$SERVERROOT . '/version.php');
+        require OC::$SERVERROOT . '/version.php';
+        /** @var $timestamp int */
+        self::$versionCache['OC_Version_Timestamp'] = $timestamp;
+        /** @var $OC_Version string */
+        self::$versionCache['OC_Version'] = $OC_Version;
+        /** @var $OC_VersionString string */
+        self::$versionCache['OC_VersionString'] = $OC_VersionString;
+        /** @var $OC_Build string */
+        self::$versionCache['OC_Build'] = $OC_Build;
+
+        /** @var $OC_Channel string */
+        self::$versionCache['OC_Channel'] = $OC_Channel;
+    }
+
+    /**
+     * generates a path for JS/CSS files. If no application is provided it will create the path for core.
+     *
+     * @param string $application application to get the files from
+     * @param string $directory directory within this application (css, js, vendor, etc)
+     * @param string $file the file inside of the above folder
+     * @return string the path
+     */
+    private static function generatePath($application, $directory, $file) {
+        if (is_null($file)) {
+            $file = $application;
+            $application = "";
+        }
+        if (!empty($application)) {
+            return "$application/$directory/$file";
+        } else {
+            return "$directory/$file";
+        }
+    }
+
+    /**
+     * add a javascript file
+     *
+     * @param string $application application id
+     * @param string|null $file filename
+     * @param bool $prepend prepend the Script to the beginning of the list
+     * @return void
+     */
+    public static function addScript($application, $file = null, $prepend = false) {
+        $path = OC_Util::generatePath($application, 'js', $file);
+
+        // core js files need separate handling
+        if ($application !== 'core' && $file !== null) {
+            self::addTranslations ( $application );
+        }
+        self::addExternalResource($application, $prepend, $path, "script");
+    }
+
+    /**
+     * add a javascript file from the vendor sub folder
+     *
+     * @param string $application application id
+     * @param string|null $file filename
+     * @param bool $prepend prepend the Script to the beginning of the list
+     * @return void
+     */
+    public static function addVendorScript($application, $file = null, $prepend = false) {
+        $path = OC_Util::generatePath($application, 'vendor', $file);
+        self::addExternalResource($application, $prepend, $path, "script");
+    }
+
+    /**
+     * add a translation JS file
+     *
+     * @param string $application application id
+     * @param string|null $languageCode language code, defaults to the current language
+     * @param bool|null $prepend prepend the Script to the beginning of the list
+     */
+    public static function addTranslations($application, $languageCode = null, $prepend = false) {
+        if (is_null($languageCode)) {
+            $languageCode = \OC::$server->getL10NFactory()->findLanguage($application);
+        }
+        if (!empty($application)) {
+            $path = "$application/l10n/$languageCode";
+        } else {
+            $path = "l10n/$languageCode";
+        }
+        self::addExternalResource($application, $prepend, $path, "script");
+    }
+
+    /**
+     * add a css file
+     *
+     * @param string $application application id
+     * @param string|null $file filename
+     * @param bool $prepend prepend the Style to the beginning of the list
+     * @return void
+     */
+    public static function addStyle($application, $file = null, $prepend = false) {
+        $path = OC_Util::generatePath($application, 'css', $file);
+        self::addExternalResource($application, $prepend, $path, "style");
+    }
+
+    /**
+     * add a css file from the vendor sub folder
+     *
+     * @param string $application application id
+     * @param string|null $file filename
+     * @param bool $prepend prepend the Style to the beginning of the list
+     * @return void
+     */
+    public static function addVendorStyle($application, $file = null, $prepend = false) {
+        $path = OC_Util::generatePath($application, 'vendor', $file);
+        self::addExternalResource($application, $prepend, $path, "style");
+    }
+
+    /**
+     * add an external resource css/js file
+     *
+     * @param string $application application id
+     * @param bool $prepend prepend the file to the beginning of the list
+     * @param string $path
+     * @param string $type (script or style)
+     * @return void
+     */
+    private static function addExternalResource($application, $prepend, $path, $type = "script") {
+
+        if ($type === "style") {
+            if (!in_array($path, self::$styles)) {
+                if ($prepend === true) {
+                    array_unshift ( self::$styles, $path );
+                } else {
+                    self::$styles[] = $path;
+                }
+            }
+        } elseif ($type === "script") {
+            if (!in_array($path, self::$scripts)) {
+                if ($prepend === true) {
+                    array_unshift ( self::$scripts, $path );
+                } else {
+                    self::$scripts [] = $path;
+                }
+            }
+        }
+    }
+
+    /**
+     * Add a custom element to the header
+     * If $text is null then the element will be written as empty element.
+     * So use "" to get a closing tag.
+     * @param string $tag tag name of the element
+     * @param array $attributes array of attributes for the element
+     * @param string $text the text content for the element
+     * @param bool $prepend prepend the header to the beginning of the list
+     */
+    public static function addHeader($tag, $attributes, $text = null, $prepend = false) {
+        $header = array(
+            'tag' => $tag,
+            'attributes' => $attributes,
+            'text' => $text
+        );
+        if ($prepend === true) {
+            array_unshift (self::$headers, $header);
+
+        } else {
+            self::$headers[] = $header;
+        }
+    }
+
+    /**
+     * check if the current server configuration is suitable for ownCloud
+     *
+     * @param \OC\SystemConfig $config
+     * @return array arrays with error messages and hints
+     */
+    public static function checkServer(\OC\SystemConfig $config) {
+        $l = \OC::$server->getL10N('lib');
+        $errors = array();
+        $CONFIG_DATADIRECTORY = $config->getValue('datadirectory', OC::$SERVERROOT . '/data');
+
+        if (!self::needUpgrade($config) && $config->getValue('installed', false)) {
+            // this check needs to be done every time
+            $errors = self::checkDataDirectoryValidity($CONFIG_DATADIRECTORY);
+        }
+
+        // Assume that if checkServer() succeeded before in this session, then all is fine.
+        if (\OC::$server->getSession()->exists('checkServer_succeeded') && \OC::$server->getSession()->get('checkServer_succeeded')) {
+            return $errors;
+        }
+
+        $webServerRestart = false;
+        $setup = new \OC\Setup(
+            $config,
+            \OC::$server->getIniWrapper(),
+            \OC::$server->getL10N('lib'),
+            \OC::$server->query(\OCP\Defaults::class),
+            \OC::$server->getLogger(),
+            \OC::$server->getSecureRandom(),
+            \OC::$server->query(\OC\Installer::class)
+        );
+
+        $urlGenerator = \OC::$server->getURLGenerator();
+
+        $availableDatabases = $setup->getSupportedDatabases();
+        if (empty($availableDatabases)) {
+            $errors[] = array(
+                'error' => $l->t('No database drivers (sqlite, mysql, or postgresql) installed.'),
+                'hint' => '' //TODO: sane hint
+            );
+            $webServerRestart = true;
+        }
+
+        // Check if config folder is writable.
+        if(!OC_Helper::isReadOnlyConfigEnabled()) {
+            if (!is_writable(OC::$configDir) or !is_readable(OC::$configDir)) {
+                $errors[] = array(
+                    'error' => $l->t('Cannot write into "config" directory'),
+                    'hint' => $l->t('This can usually be fixed by giving the webserver write access to the config directory. See %s',
+                        [ $urlGenerator->linkToDocs('admin-dir_permissions') ]) . '. '
+                        . $l->t('Or, if you prefer to keep config.php file read only, set the option "config_is_read_only" to true in it. See %s',
+                        [ $urlGenerator->linkToDocs('admin-config') ] )
+                );
+            }
+        }
+
+        // Check if there is a writable install folder.
+        if ($config->getValue('appstoreenabled', true)) {
+            if (OC_App::getInstallPath() === null
+                || !is_writable(OC_App::getInstallPath())
+                || !is_readable(OC_App::getInstallPath())
+            ) {
+                $errors[] = array(
+                    'error' => $l->t('Cannot write into "apps" directory'),
+                    'hint' => $l->t('This can usually be fixed by giving the webserver write access to the apps directory'
+                        . ' or disabling the appstore in the config file. See %s',
+                        [$urlGenerator->linkToDocs('admin-dir_permissions')])
+                );
+            }
+        }
+        // Create root dir.
+        if ($config->getValue('installed', false)) {
+            if (!is_dir($CONFIG_DATADIRECTORY)) {
+                $success = @mkdir($CONFIG_DATADIRECTORY);
+                if ($success) {
+                    $errors = array_merge($errors, self::checkDataDirectoryPermissions($CONFIG_DATADIRECTORY));
+                } else {
+                    $errors[] = [
+                        'error' => $l->t('Cannot create "data" directory'),
+                        'hint' => $l->t('This can usually be fixed by giving the webserver write access to the root directory. See %s',
+                            [$urlGenerator->linkToDocs('admin-dir_permissions')])
+                    ];
+                }
+            } else if (!is_writable($CONFIG_DATADIRECTORY) or !is_readable($CONFIG_DATADIRECTORY)) {
+                //common hint for all file permissions error messages
+                $permissionsHint = $l->t('Permissions can usually be fixed by giving the webserver write access to the root directory. See %s.',
+                    [$urlGenerator->linkToDocs('admin-dir_permissions')]);
+                $errors[] = [
+                    'error' => 'Your data directory is not writable',
+                    'hint' => $permissionsHint
+                ];
+            } else {
+                $errors = array_merge($errors, self::checkDataDirectoryPermissions($CONFIG_DATADIRECTORY));
+            }
+        }
+
+        if (!OC_Util::isSetLocaleWorking()) {
+            $errors[] = array(
+                'error' => $l->t('Setting locale to %s failed',
+                    array('en_US.UTF-8/fr_FR.UTF-8/es_ES.UTF-8/de_DE.UTF-8/ru_RU.UTF-8/'
+                        . 'pt_BR.UTF-8/it_IT.UTF-8/ja_JP.UTF-8/zh_CN.UTF-8')),
+                'hint' => $l->t('Please install one of these locales on your system and restart your webserver.')
+            );
+        }
+
+        // Contains the dependencies that should be checked against
+        // classes = class_exists
+        // functions = function_exists
+        // defined = defined
+        // ini = ini_get
+        // If the dependency is not found the missing module name is shown to the EndUser
+        // When adding new checks always verify that they pass on Travis as well
+        // for ini settings, see https://github.com/owncloud/administration/blob/master/travis-ci/custom.ini
+        $dependencies = array(
+            'classes' => array(
+                'ZipArchive' => 'zip',
+                'DOMDocument' => 'dom',
+                'XMLWriter' => 'XMLWriter',
+                'XMLReader' => 'XMLReader',
+            ),
+            'functions' => [
+                'xml_parser_create' => 'libxml',
+                'mb_strcut' => 'mb multibyte',
+                'ctype_digit' => 'ctype',
+                'json_encode' => 'JSON',
+                'gd_info' => 'GD',
+                'gzencode' => 'zlib',
+                'iconv' => 'iconv',
+                'simplexml_load_string' => 'SimpleXML',
+                'hash' => 'HASH Message Digest Framework',
+                'curl_init' => 'cURL',
+                'openssl_verify' => 'OpenSSL',
+            ],
+            'defined' => array(
+                'PDO::ATTR_DRIVER_NAME' => 'PDO'
+            ),
+            'ini' => [
+                'default_charset' => 'UTF-8',
+            ],
+        );
+        $missingDependencies = array();
+        $invalidIniSettings = [];
+        $moduleHint = $l->t('Please ask your server administrator to install the module.');
+
+        /**
+         * FIXME: The dependency check does not work properly on HHVM on the moment
+         *        and prevents installation. Once HHVM is more compatible with our
+         *        approach to check for these values we should re-enable those
+         *        checks.
+         */
+        $iniWrapper = \OC::$server->getIniWrapper();
+        if (!self::runningOnHhvm()) {
+            foreach ($dependencies['classes'] as $class => $module) {
+                if (!class_exists($class)) {
+                    $missingDependencies[] = $module;
+                }
+            }
+            foreach ($dependencies['functions'] as $function => $module) {
+                if (!function_exists($function)) {
+                    $missingDependencies[] = $module;
+                }
+            }
+            foreach ($dependencies['defined'] as $defined => $module) {
+                if (!defined($defined)) {
+                    $missingDependencies[] = $module;
+                }
+            }
+            foreach ($dependencies['ini'] as $setting => $expected) {
+                if (is_bool($expected)) {
+                    if ($iniWrapper->getBool($setting) !== $expected) {
+                        $invalidIniSettings[] = [$setting, $expected];
+                    }
+                }
+                if (is_int($expected)) {
+                    if ($iniWrapper->getNumeric($setting) !== $expected) {
+                        $invalidIniSettings[] = [$setting, $expected];
+                    }
+                }
+                if (is_string($expected)) {
+                    if (strtolower($iniWrapper->getString($setting)) !== strtolower($expected)) {
+                        $invalidIniSettings[] = [$setting, $expected];
+                    }
+                }
+            }
+        }
+
+        foreach($missingDependencies as $missingDependency) {
+            $errors[] = array(
+                'error' => $l->t('PHP module %s not installed.', array($missingDependency)),
+                'hint' => $moduleHint
+            );
+            $webServerRestart = true;
+        }
+        foreach($invalidIniSettings as $setting) {
+            if(is_bool($setting[1])) {
+                $setting[1] = $setting[1] ? 'on' : 'off';
+            }
+            $errors[] = [
+                'error' => $l->t('PHP setting "%s" is not set to "%s".', [$setting[0], var_export($setting[1], true)]),
+                'hint' =>  $l->t('Adjusting this setting in php.ini will make Nextcloud run again')
+            ];
+            $webServerRestart = true;
+        }
+
+        /**
+         * The mbstring.func_overload check can only be performed if the mbstring
+         * module is installed as it will return null if the checking setting is
+         * not available and thus a check on the boolean value fails.
+         *
+         * TODO: Should probably be implemented in the above generic dependency
+         *       check somehow in the long-term.
+         */
+        if($iniWrapper->getBool('mbstring.func_overload') !== null &&
+            $iniWrapper->getBool('mbstring.func_overload') === true) {
+            $errors[] = array(
+                'error' => $l->t('mbstring.func_overload is set to "%s" instead of the expected value "0"', [$iniWrapper->getString('mbstring.func_overload')]),
+                'hint' => $l->t('To fix this issue set <code>mbstring.func_overload</code> to <code>0</code> in your php.ini')
+            );
+        }
+
+        if(function_exists('xml_parser_create') &&
+            LIBXML_LOADED_VERSION < 20700 ) {
+            $version = LIBXML_LOADED_VERSION;
+            $major = floor($version/10000);
+            $version -= ($major * 10000);
+            $minor = floor($version/100);
+            $version -= ($minor * 100);
+            $patch = $version;
+            $errors[] = array(
+                'error' => $l->t('libxml2 2.7.0 is at least required. Currently %s is installed.', [$major . '.' . $minor . '.' . $patch]),
+                'hint' => $l->t('To fix this issue update your libxml2 version and restart your web server.')
+            );
+        }
+
+        if (!self::isAnnotationsWorking()) {
+            $errors[] = array(
+                'error' => $l->t('PHP is apparently set up to strip inline doc blocks. This will make several core apps inaccessible.'),
+                'hint' => $l->t('This is probably caused by a cache/accelerator such as Zend OPcache or eAccelerator.')
+            );
+        }
+
+        if (!\OC::$CLI && $webServerRestart) {
+            $errors[] = array(
+                'error' => $l->t('PHP modules have been installed, but they are still listed as missing?'),
+                'hint' => $l->t('Please ask your server administrator to restart the web server.')
+            );
+        }
+
+        $errors = array_merge($errors, self::checkDatabaseVersion());
+
+        // Cache the result of this function
+        \OC::$server->getSession()->set('checkServer_succeeded', count($errors) == 0);
+
+        return $errors;
+    }
+
+    /**
+     * Check the database version
+     *
+     * @return array errors array
+     */
+    public static function checkDatabaseVersion() {
+        $l = \OC::$server->getL10N('lib');
+        $errors = array();
+        $dbType = \OC::$server->getSystemConfig()->getValue('dbtype', 'sqlite');
+        if ($dbType === 'pgsql') {
+            // check PostgreSQL version
+            try {
+                $result = \OC_DB::executeAudited('SHOW SERVER_VERSION');
+                $data = $result->fetchRow();
+                if (isset($data['server_version'])) {
+                    $version = $data['server_version'];
+                    if (version_compare($version, '9.0.0', '<')) {
+                        $errors[] = array(
+                            'error' => $l->t('PostgreSQL >= 9 required'),
+                            'hint' => $l->t('Please upgrade your database version')
+                        );
+                    }
+                }
+            } catch (\Doctrine\DBAL\DBALException $e) {
+                $logger = \OC::$server->getLogger();
+                $logger->warning('Error occurred while checking PostgreSQL version, assuming >= 9');
+                $logger->logException($e);
+            }
+        }
+        return $errors;
+    }
+
+    /**
+     * Check for correct file permissions of data directory
+     *
+     * @param string $dataDirectory
+     * @return array arrays with error messages and hints
+     */
+    public static function checkDataDirectoryPermissions($dataDirectory) {
+        if(\OC::$server->getConfig()->getSystemValue('check_data_directory_permissions', true) === false) {
+            return  [];
+        }
+        $l = \OC::$server->getL10N('lib');
+        $errors = [];
+        $permissionsModHint = $l->t('Please change the permissions to 0770 so that the directory'
+            . ' cannot be listed by other users.');
+        $perms = substr(decoct(@fileperms($dataDirectory)), -3);
+        if (substr($perms, -1) !== '0') {
+            chmod($dataDirectory, 0770);
+            clearstatcache();
+            $perms = substr(decoct(@fileperms($dataDirectory)), -3);
+            if ($perms[2] !== '0') {
+                $errors[] = [
+                    'error' => $l->t('Your data directory is readable by other users'),
+                    'hint' => $permissionsModHint
+                ];
+            }
+        }
+        return $errors;
+    }
+
+    /**
+     * Check that the data directory exists and is valid by
+     * checking the existence of the ".ocdata" file.
+     *
+     * @param string $dataDirectory data directory path
+     * @return array errors found
+     */
+    public static function checkDataDirectoryValidity($dataDirectory) {
+        $l = \OC::$server->getL10N('lib');
+        $errors = [];
+        if ($dataDirectory[0] !== '/') {
+            $errors[] = [
+                'error' => $l->t('Your data directory must be an absolute path'),
+                'hint' => $l->t('Check the value of "datadirectory" in your configuration')
+            ];
+        }
+        if (!file_exists($dataDirectory . '/.ocdata')) {
+            $errors[] = [
+                'error' => $l->t('Your data directory is invalid'),
+                'hint' => $l->t('Ensure there is a file called ".ocdata"' .
+                    ' in the root of the data directory.')
+            ];
+        }
+        return $errors;
+    }
+
+    /**
+     * Check if the user is logged in, redirects to home if not. With
+     * redirect URL parameter to the request URI.
+     *
+     * @return void
+     */
+    public static function checkLoggedIn() {
+        // Check if we are a user
+        if (!\OC::$server->getUserSession()->isLoggedIn()) {
+            header('Location: ' . \OC::$server->getURLGenerator()->linkToRoute(
+                        'core.login.showLoginForm',
+                        [
+                            'redirect_url' => \OC::$server->getRequest()->getRequestUri(),
+                        ]
+                    )
+            );
+            exit();
+        }
+        // Redirect to 2FA challenge selection if 2FA challenge was not solved yet
+        if (\OC::$server->getTwoFactorAuthManager()->needsSecondFactor(\OC::$server->getUserSession()->getUser())) {
+            header('Location: ' . \OC::$server->getURLGenerator()->linkToRoute('core.TwoFactorChallenge.selectChallenge'));
+            exit();
+        }
+    }
+
+    /**
+     * Check if the user is a admin, redirects to home if not
+     *
+     * @return void
+     */
+    public static function checkAdminUser() {
+        OC_Util::checkLoggedIn();
+        if (!OC_User::isAdminUser(OC_User::getUser())) {
+            header('Location: ' . \OCP\Util::linkToAbsolute('', 'index.php'));
+            exit();
+        }
+    }
+
+    /**
+     * Check if the user is a subadmin, redirects to home if not
+     *
+     * @return null|boolean $groups where the current user is subadmin
+     */
+    public static function checkSubAdminUser() {
+        OC_Util::checkLoggedIn();
+        $userObject = \OC::$server->getUserSession()->getUser();
+        $isSubAdmin = false;
+        if($userObject !== null) {
+            $isSubAdmin = \OC::$server->getGroupManager()->getSubAdmin()->isSubAdmin($userObject);
+        }
+
+        if (!$isSubAdmin) {
+            header('Location: ' . \OCP\Util::linkToAbsolute('', 'index.php'));
+            exit();
+        }
+        return true;
+    }
+
+    /**
+     * Returns the URL of the default page
+     * based on the system configuration and
+     * the apps visible for the current user
+     *
+     * @return string URL
+     * @suppress PhanDeprecatedFunction
+     */
+    public static function getDefaultPageUrl() {
+        $urlGenerator = \OC::$server->getURLGenerator();
+        // Deny the redirect if the URL contains a @
+        // This prevents unvalidated redirects like ?redirect_url=:user@domain.com
+        if (isset($_REQUEST['redirect_url']) && strpos($_REQUEST['redirect_url'], '@') === false) {
+            $location = $urlGenerator->getAbsoluteURL(urldecode($_REQUEST['redirect_url']));
+        } else {
+            $defaultPage = \OC::$server->getConfig()->getAppValue('core', 'defaultpage');
+            if ($defaultPage) {
+                $location = $urlGenerator->getAbsoluteURL($defaultPage);
+            } else {
+                $appId = 'files';
+                $config = \OC::$server->getConfig();
+                $defaultApps = explode(',', $config->getSystemValue('defaultapp', 'files'));
+                // find the first app that is enabled for the current user
+                foreach ($defaultApps as $defaultApp) {
+                    $defaultApp = OC_App::cleanAppId(strip_tags($defaultApp));
+                    if (static::getAppManager()->isEnabledForUser($defaultApp)) {
+                        $appId = $defaultApp;
+                        break;
+                    }
+                }
+
+                if($config->getSystemValue('htaccess.IgnoreFrontController', false) === true || getenv('front_controller_active') === 'true') {
+                    $location = $urlGenerator->getAbsoluteURL('/apps/' . $appId . '/');
+                } else {
+                    $location = $urlGenerator->getAbsoluteURL('/index.php/apps/' . $appId . '/');
+                }
+            }
+        }
+        return $location;
+    }
+
+    /**
+     * Redirect to the user default page
+     *
+     * @return void
+     */
+    public static function redirectToDefaultPage() {
+        $location = self::getDefaultPageUrl();
+        header('Location: ' . $location);
+        exit();
+    }
+
+    /**
+     * get an id unique for this instance
+     *
+     * @return string
+     */
+    public static function getInstanceId() {
+        $id = \OC::$server->getSystemConfig()->getValue('instanceid', null);
+        if (is_null($id)) {
+            // We need to guarantee at least one letter in instanceid so it can be used as the session_name
+            $id = 'oc' . \OC::$server->getSecureRandom()->generate(10, \OCP\Security\ISecureRandom::CHAR_LOWER.\OCP\Security\ISecureRandom::CHAR_DIGITS);
+            \OC::$server->getSystemConfig()->setValue('instanceid', $id);
+        }
+        return $id;
+    }
+
+    /**
+     * Public function to sanitize HTML
+     *
+     * This function is used to sanitize HTML and should be applied on any
+     * string or array of strings before displaying it on a web page.
+     *
+     * @param string|array $value
+     * @return string|array an array of sanitized strings or a single sanitized string, depends on the input parameter.
+     */
+    public static function sanitizeHTML($value) {
+        if (is_array($value)) {
+            $value = array_map(function($value) {
+                return self::sanitizeHTML($value);
+            }, $value);
+        } else {
+            // Specify encoding for PHP<5.4
+            $value = htmlspecialchars((string)$value, ENT_QUOTES, 'UTF-8');
+        }
+        return $value;
+    }
+
+    /**
+     * Public function to encode url parameters
+     *
+     * This function is used to encode path to file before output.
+     * Encoding is done according to RFC 3986 with one exception:
+     * Character '/' is preserved as is.
+     *
+     * @param string $component part of URI to encode
+     * @return string
+     */
+    public static function encodePath($component) {
+        $encoded = rawurlencode($component);
+        $encoded = str_replace('%2F', '/', $encoded);
+        return $encoded;
+    }
+
+
+    public function createHtaccessTestFile(\OCP\IConfig $config) {
+        // php dev server does not support htaccess
+        if (php_sapi_name() === 'cli-server') {
+            return false;
+        }
+
+        // testdata
+        $fileName = '/htaccesstest.txt';
+        $testContent = 'This is used for testing whether htaccess is properly enabled to disallow access from the outside. This file can be safely removed.';
+
+        // creating a test file
+        $testFile = $config->getSystemValue('datadirectory', OC::$SERVERROOT . '/data') . '/' . $fileName;
+
+        if (file_exists($testFile)) {// already running this test, possible recursive call
+            return false;
+        }
+
+        $fp = @fopen($testFile, 'w');
+        if (!$fp) {
+            throw new OC\HintException('Can\'t create test file to check for working .htaccess file.',
+                'Make sure it is possible for the webserver to write to ' . $testFile);
+        }
+        fwrite($fp, $testContent);
+        fclose($fp);
+
+        return $testContent;
+    }
+
+    /**
+     * Check if the .htaccess file is working
+     * @param \OCP\IConfig $config
+     * @return bool
+     * @throws Exception
+     * @throws \OC\HintException If the test file can't get written.
+     */
+    public function isHtaccessWorking(\OCP\IConfig $config) {
+
+        if (\OC::$CLI || !$config->getSystemValue('check_for_working_htaccess', true)) {
+            return true;
+        }
+
+        $testContent = $this->createHtaccessTestFile($config);
+        if ($testContent === false) {
+            return false;
+        }
+
+        $fileName = '/htaccesstest.txt';
+        $testFile = $config->getSystemValue('datadirectory', OC::$SERVERROOT . '/data') . '/' . $fileName;
+
+        // accessing the file via http
+        $url = \OC::$server->getURLGenerator()->getAbsoluteURL(OC::$WEBROOT . '/data' . $fileName);
+        try {
+            $content = \OC::$server->getHTTPClientService()->newClient()->get($url)->getBody();
+        } catch (\Exception $e) {
+            $content = false;
+        }
+
+        // cleanup
+        @unlink($testFile);
+
+        /*
 		 * If the content is not equal to test content our .htaccess
 		 * is working as required
 		 */
-		return $content !== $testContent;
-	}
-
-	/**
-	 * Check if the setlocal call does not work. This can happen if the right
-	 * local packages are not available on the server.
-	 *
-	 * @return bool
-	 */
-	public static function isSetLocaleWorking() {
-		\Patchwork\Utf8\Bootup::initLocale();
-		if ('' === basename('§')) {
-			return false;
-		}
-		return true;
-	}
-
-	/**
-	 * Check if it's possible to get the inline annotations
-	 *
-	 * @return bool
-	 */
-	public static function isAnnotationsWorking() {
-		$reflection = new \ReflectionMethod(__METHOD__);
-		$docs = $reflection->getDocComment();
-
-		return (is_string($docs) && strlen($docs) > 50);
-	}
-
-	/**
-	 * Check if the PHP module fileinfo is loaded.
-	 *
-	 * @return bool
-	 */
-	public static function fileInfoLoaded() {
-		return function_exists('finfo_open');
-	}
-
-	/**
-	 * clear all levels of output buffering
-	 *
-	 * @return void
-	 */
-	public static function obEnd() {
-		while (ob_get_level()) {
-			ob_end_clean();
-		}
-	}
-
-	/**
-	 * Checks whether the server is running on Mac OS X
-	 *
-	 * @return bool true if running on Mac OS X, false otherwise
-	 */
-	public static function runningOnMac() {
-		return (strtoupper(substr(PHP_OS, 0, 6)) === 'DARWIN');
-	}
-
-	/**
-	 * Checks whether server is running on HHVM
-	 *
-	 * @return bool True if running on HHVM, false otherwise
-	 */
-	public static function runningOnHhvm() {
-		return defined('HHVM_VERSION');
-	}
-
-	/**
-	 * Handles the case that there may not be a theme, then check if a "default"
-	 * theme exists and take that one
-	 *
-	 * @return string the theme
-	 */
-	public static function getTheme() {
-		$theme = \OC::$server->getSystemConfig()->getValue("theme", '');
-
-		if ($theme === '') {
-			if (is_dir(OC::$SERVERROOT . '/themes/default')) {
-				$theme = 'default';
-			}
-		}
-
-		return $theme;
-	}
-
-	/**
-	 * Clear a single file from the opcode cache
-	 * This is useful for writing to the config file
-	 * in case the opcode cache does not re-validate files
-	 * Returns true if successful, false if unsuccessful:
-	 * caller should fall back on clearing the entire cache
-	 * with clearOpcodeCache() if unsuccessful
-	 *
-	 * @param string $path the path of the file to clear from the cache
-	 * @return bool true if underlying function returns true, otherwise false
-	 */
-	public static function deleteFromOpcodeCache($path) {
-		$ret = false;
-		if ($path) {
-			// APC >= 3.1.1
-			if (function_exists('apc_delete_file')) {
-				$ret = @apc_delete_file($path);
-			}
-			// Zend OpCache >= 7.0.0, PHP >= 5.5.0
-			if (function_exists('opcache_invalidate')) {
-				$ret = @opcache_invalidate($path);
-			}
-		}
-		return $ret;
-	}
-
-	/**
-	 * Clear the opcode cache if one exists
-	 * This is necessary for writing to the config file
-	 * in case the opcode cache does not re-validate files
-	 *
-	 * @return void
-	 * @suppress PhanDeprecatedFunction
-	 * @suppress PhanUndeclaredConstant
-	 */
-	public static function clearOpcodeCache() {
-		// APC
-		if (function_exists('apc_clear_cache')) {
-			apc_clear_cache();
-		}
-		// Zend Opcache
-		if (function_exists('accelerator_reset')) {
-			accelerator_reset();
-		}
-		// Opcache (PHP >= 5.5)
-		if (function_exists('opcache_reset')) {
-			@opcache_reset();
-		}
-	}
-
-	/**
-	 * Normalize a unicode string
-	 *
-	 * @param string $value a not normalized string
-	 * @return bool|string
-	 */
-	public static function normalizeUnicode($value) {
-		if(Normalizer::isNormalized($value)) {
-			return $value;
-		}
-
-		$normalizedValue = Normalizer::normalize($value);
-		if ($normalizedValue === null || $normalizedValue === false) {
-			\OC::$server->getLogger()->warning('normalizing failed for "' . $value . '"', ['app' => 'core']);
-			return $value;
-		}
-
-		return $normalizedValue;
-	}
-
-	/**
-	 * A human readable string is generated based on version and build number
-	 *
-	 * @return string
-	 */
-	public static function getHumanVersion() {
-		$version = OC_Util::getVersionString();
-		$build = OC_Util::getBuild();
-		if (!empty($build) and OC_Util::getChannel() === 'daily') {
-			$version .= ' Build:' . $build;
-		}
-		return $version;
-	}
-
-	/**
-	 * Returns whether the given file name is valid
-	 *
-	 * @param string $file file name to check
-	 * @return bool true if the file name is valid, false otherwise
-	 * @deprecated use \OC\Files\View::verifyPath()
-	 */
-	public static function isValidFileName($file) {
-		$trimmed = trim($file);
-		if ($trimmed === '') {
-			return false;
-		}
-		if (\OC\Files\Filesystem::isIgnoredDir($trimmed)) {
-			return false;
-		}
-
-		// detect part files
-		if (preg_match('/' . \OCP\Files\FileInfo::BLACKLIST_FILES_REGEX . '/', $trimmed) !== 0) {
-			return false;
-		}
-
-		foreach (str_split($trimmed) as $char) {
-			if (strpos(\OCP\Constants::FILENAME_INVALID_CHARS, $char) !== false) {
-				return false;
-			}
-		}
-		return true;
-	}
-
-	/**
-	 * Check whether the instance needs to perform an upgrade,
-	 * either when the core version is higher or any app requires
-	 * an upgrade.
-	 *
-	 * @param \OC\SystemConfig $config
-	 * @return bool whether the core or any app needs an upgrade
-	 * @throws \OC\HintException When the upgrade from the given version is not allowed
-	 */
-	public static function needUpgrade(\OC\SystemConfig $config) {
-		if ($config->getValue('installed', false)) {
-			$installedVersion = $config->getValue('version', '0.0.0');
-			$currentVersion = implode('.', \OCP\Util::getVersion());
-			$versionDiff = version_compare($currentVersion, $installedVersion);
-			if ($versionDiff > 0) {
-				return true;
-			} else if ($config->getValue('debug', false) && $versionDiff < 0) {
-				// downgrade with debug
-				$installedMajor = explode('.', $installedVersion);
-				$installedMajor = $installedMajor[0] . '.' . $installedMajor[1];
-				$currentMajor = explode('.', $currentVersion);
-				$currentMajor = $currentMajor[0] . '.' . $currentMajor[1];
-				if ($installedMajor === $currentMajor) {
-					// Same major, allow downgrade for developers
-					return true;
-				} else {
-					// downgrade attempt, throw exception
-					throw new \OC\HintException('Downgrading is not supported and is likely to cause unpredictable issues (from ' . $installedVersion . ' to ' . $currentVersion . ')');
-				}
-			} else if ($versionDiff < 0) {
-				// downgrade attempt, throw exception
-				throw new \OC\HintException('Downgrading is not supported and is likely to cause unpredictable issues (from ' . $installedVersion . ' to ' . $currentVersion . ')');
-			}
-
-			// also check for upgrades for apps (independently from the user)
-			$apps = \OC_App::getEnabledApps(false, true);
-			$shouldUpgrade = false;
-			foreach ($apps as $app) {
-				if (\OC_App::shouldUpgrade($app)) {
-					$shouldUpgrade = true;
-					break;
-				}
-			}
-			return $shouldUpgrade;
-		} else {
-			return false;
-		}
-	}
-
-	/**
-	 * is this Internet explorer ?
-	 *
-	 * @return boolean
-	 */
-	public static function isIe() {
-		if (!isset($_SERVER['HTTP_USER_AGENT'])) {
-			return false;
-		}
-
-		return preg_match(Request::USER_AGENT_IE, $_SERVER['HTTP_USER_AGENT']) === 1;
-	}
+        return $content !== $testContent;
+    }
+
+    /**
+     * Check if the setlocal call does not work. This can happen if the right
+     * local packages are not available on the server.
+     *
+     * @return bool
+     */
+    public static function isSetLocaleWorking() {
+        \Patchwork\Utf8\Bootup::initLocale();
+        if ('' === basename('§')) {
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Check if it's possible to get the inline annotations
+     *
+     * @return bool
+     */
+    public static function isAnnotationsWorking() {
+        $reflection = new \ReflectionMethod(__METHOD__);
+        $docs = $reflection->getDocComment();
+
+        return (is_string($docs) && strlen($docs) > 50);
+    }
+
+    /**
+     * Check if the PHP module fileinfo is loaded.
+     *
+     * @return bool
+     */
+    public static function fileInfoLoaded() {
+        return function_exists('finfo_open');
+    }
+
+    /**
+     * clear all levels of output buffering
+     *
+     * @return void
+     */
+    public static function obEnd() {
+        while (ob_get_level()) {
+            ob_end_clean();
+        }
+    }
+
+    /**
+     * Checks whether the server is running on Mac OS X
+     *
+     * @return bool true if running on Mac OS X, false otherwise
+     */
+    public static function runningOnMac() {
+        return (strtoupper(substr(PHP_OS, 0, 6)) === 'DARWIN');
+    }
+
+    /**
+     * Checks whether server is running on HHVM
+     *
+     * @return bool True if running on HHVM, false otherwise
+     */
+    public static function runningOnHhvm() {
+        return defined('HHVM_VERSION');
+    }
+
+    /**
+     * Handles the case that there may not be a theme, then check if a "default"
+     * theme exists and take that one
+     *
+     * @return string the theme
+     */
+    public static function getTheme() {
+        $theme = \OC::$server->getSystemConfig()->getValue("theme", '');
+
+        if ($theme === '') {
+            if (is_dir(OC::$SERVERROOT . '/themes/default')) {
+                $theme = 'default';
+            }
+        }
+
+        return $theme;
+    }
+
+    /**
+     * Clear a single file from the opcode cache
+     * This is useful for writing to the config file
+     * in case the opcode cache does not re-validate files
+     * Returns true if successful, false if unsuccessful:
+     * caller should fall back on clearing the entire cache
+     * with clearOpcodeCache() if unsuccessful
+     *
+     * @param string $path the path of the file to clear from the cache
+     * @return bool true if underlying function returns true, otherwise false
+     */
+    public static function deleteFromOpcodeCache($path) {
+        $ret = false;
+        if ($path) {
+            // APC >= 3.1.1
+            if (function_exists('apc_delete_file')) {
+                $ret = @apc_delete_file($path);
+            }
+            // Zend OpCache >= 7.0.0, PHP >= 5.5.0
+            if (function_exists('opcache_invalidate')) {
+                $ret = @opcache_invalidate($path);
+            }
+        }
+        return $ret;
+    }
+
+    /**
+     * Clear the opcode cache if one exists
+     * This is necessary for writing to the config file
+     * in case the opcode cache does not re-validate files
+     *
+     * @return void
+     * @suppress PhanDeprecatedFunction
+     * @suppress PhanUndeclaredConstant
+     */
+    public static function clearOpcodeCache() {
+        // APC
+        if (function_exists('apc_clear_cache')) {
+            apc_clear_cache();
+        }
+        // Zend Opcache
+        if (function_exists('accelerator_reset')) {
+            accelerator_reset();
+        }
+        // Opcache (PHP >= 5.5)
+        if (function_exists('opcache_reset')) {
+            @opcache_reset();
+        }
+    }
+
+    /**
+     * Normalize a unicode string
+     *
+     * @param string $value a not normalized string
+     * @return bool|string
+     */
+    public static function normalizeUnicode($value) {
+        if(Normalizer::isNormalized($value)) {
+            return $value;
+        }
+
+        $normalizedValue = Normalizer::normalize($value);
+        if ($normalizedValue === null || $normalizedValue === false) {
+            \OC::$server->getLogger()->warning('normalizing failed for "' . $value . '"', ['app' => 'core']);
+            return $value;
+        }
+
+        return $normalizedValue;
+    }
+
+    /**
+     * A human readable string is generated based on version and build number
+     *
+     * @return string
+     */
+    public static function getHumanVersion() {
+        $version = OC_Util::getVersionString();
+        $build = OC_Util::getBuild();
+        if (!empty($build) and OC_Util::getChannel() === 'daily') {
+            $version .= ' Build:' . $build;
+        }
+        return $version;
+    }
+
+    /**
+     * Returns whether the given file name is valid
+     *
+     * @param string $file file name to check
+     * @return bool true if the file name is valid, false otherwise
+     * @deprecated use \OC\Files\View::verifyPath()
+     */
+    public static function isValidFileName($file) {
+        $trimmed = trim($file);
+        if ($trimmed === '') {
+            return false;
+        }
+        if (\OC\Files\Filesystem::isIgnoredDir($trimmed)) {
+            return false;
+        }
+
+        // detect part files
+        if (preg_match('/' . \OCP\Files\FileInfo::BLACKLIST_FILES_REGEX . '/', $trimmed) !== 0) {
+            return false;
+        }
+
+        foreach (str_split($trimmed) as $char) {
+            if (strpos(\OCP\Constants::FILENAME_INVALID_CHARS, $char) !== false) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Check whether the instance needs to perform an upgrade,
+     * either when the core version is higher or any app requires
+     * an upgrade.
+     *
+     * @param \OC\SystemConfig $config
+     * @return bool whether the core or any app needs an upgrade
+     * @throws \OC\HintException When the upgrade from the given version is not allowed
+     */
+    public static function needUpgrade(\OC\SystemConfig $config) {
+        if ($config->getValue('installed', false)) {
+            $installedVersion = $config->getValue('version', '0.0.0');
+            $currentVersion = implode('.', \OCP\Util::getVersion());
+            $versionDiff = version_compare($currentVersion, $installedVersion);
+            if ($versionDiff > 0) {
+                return true;
+            } else if ($config->getValue('debug', false) && $versionDiff < 0) {
+                // downgrade with debug
+                $installedMajor = explode('.', $installedVersion);
+                $installedMajor = $installedMajor[0] . '.' . $installedMajor[1];
+                $currentMajor = explode('.', $currentVersion);
+                $currentMajor = $currentMajor[0] . '.' . $currentMajor[1];
+                if ($installedMajor === $currentMajor) {
+                    // Same major, allow downgrade for developers
+                    return true;
+                } else {
+                    // downgrade attempt, throw exception
+                    throw new \OC\HintException('Downgrading is not supported and is likely to cause unpredictable issues (from ' . $installedVersion . ' to ' . $currentVersion . ')');
+                }
+            } else if ($versionDiff < 0) {
+                // downgrade attempt, throw exception
+                throw new \OC\HintException('Downgrading is not supported and is likely to cause unpredictable issues (from ' . $installedVersion . ' to ' . $currentVersion . ')');
+            }
+
+            // also check for upgrades for apps (independently from the user)
+            $apps = \OC_App::getEnabledApps(false, true);
+            $shouldUpgrade = false;
+            foreach ($apps as $app) {
+                if (\OC_App::shouldUpgrade($app)) {
+                    $shouldUpgrade = true;
+                    break;
+                }
+            }
+            return $shouldUpgrade;
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * is this Internet explorer ?
+     *
+     * @return boolean
+     */
+    public static function isIe() {
+        if (!isset($_SERVER['HTTP_USER_AGENT'])) {
+            return false;
+        }
+
+        return preg_match(Request::USER_AGENT_IE, $_SERVER['HTTP_USER_AGENT']) === 1;
+    }
 
 }