another attempt to enforce session ID regeneration on login

[tt-rss.git] / include / functions.php

<?php
	define('EXPECTED_CONFIG_VERSION', 26);
	define('SCHEMA_VERSION', 134);

	define('LABEL_BASE_INDEX', -1024);
	define('PLUGIN_FEED_BASE_INDEX', -128);

	define('COOKIE_LIFETIME_LONG', 86400*365);

	$fetch_last_error = false;
	$fetch_last_error_code = false;
	$fetch_last_content_type = false;
	$fetch_last_error_content = false; // curl only for the time being
	$fetch_effective_url = false;
	$fetch_curl_used = false;
	$suppress_debugging = false;

	libxml_disable_entity_loader(true);

	// separate test because this is included before sanity checks
	if (function_exists("mb_internal_encoding")) mb_internal_encoding("UTF-8");

	date_default_timezone_set('UTC');
	if (defined('E_DEPRECATED')) {
		error_reporting(E_ALL & ~E_NOTICE & ~E_DEPRECATED);
	} else {
		error_reporting(E_ALL & ~E_NOTICE);
	}

	require_once 'config.php';

	/**
	 * Define a constant if not already defined
	 */
	function define_default($name, $value) {
		defined($name) or define($name, $value);
	}

	/* Some tunables you can override in config.php using define():	*/

	define_default('FEED_FETCH_TIMEOUT', 45);
	// How may seconds to wait for response when requesting feed from a site
	define_default('FEED_FETCH_NO_CACHE_TIMEOUT', 15);
	// How may seconds to wait for response when requesting feed from a
	// site when that feed wasn't cached before
	define_default('FILE_FETCH_TIMEOUT', 45);
	// Default timeout when fetching files from remote sites
	define_default('FILE_FETCH_CONNECT_TIMEOUT', 15);
	// How many seconds to wait for initial response from website when
	// fetching files from remote sites
	define_default('DAEMON_UPDATE_LOGIN_LIMIT', 30);
	// stop updating feeds if users haven't logged in for X days
	define_default('DAEMON_FEED_LIMIT', 500);
	// feed limit for one update batch
	define_default('DAEMON_SLEEP_INTERVAL', 120);
	// default sleep interval between feed updates (sec)
	define_default('MIN_CACHE_FILE_SIZE', 1024);
	// do not cache files smaller than that (bytes)
	define_default('MAX_CACHE_FILE_SIZE', 64*1024*1024);
	// do not cache files larger than that (bytes)
	define_default('MAX_DOWNLOAD_FILE_SIZE', 16*1024*1024);
	// do not download general files larger than that (bytes)
	define_default('CACHE_MAX_DAYS', 7);
	// max age in days for various automatically cached (temporary) files
	define_default('MAX_CONDITIONAL_INTERVAL', 3600*12);
	// max interval between forced unconditional updates for servers
	// not complying with http if-modified-since (seconds)

	/* tunables end here */

	if (DB_TYPE == "pgsql") {
		define('SUBSTRING_FOR_DATE', 'SUBSTRING_FOR_DATE');
	} else {
		define('SUBSTRING_FOR_DATE', 'SUBSTRING');
	}

	/**
	 * Return available translations names.
	 *
	 * @access public
	 * @return array A array of available translations.
	 */
	function get_translations() {
		$tr = array(
					"auto"  => "Detect automatically",
					"ar_SA" => "العربيّة (Arabic)",
					"bg_BG" => "Bulgarian",
					"da_DA" => "Dansk",
					"ca_CA" => "Català",
					"cs_CZ" => "Česky",
					"en_US" => "English",
					"el_GR" => "Ελληνικά",
					"es_ES" => "Español (España)",
					"es_LA" => "Español",
					"de_DE" => "Deutsch",
					"fr_FR" => "Français",
					"hu_HU" => "Magyar (Hungarian)",
					"it_IT" => "Italiano",
					"ja_JP" => "日本語 (Japanese)",
					"lv_LV" => "Latviešu",
					"nb_NO" => "Norwegian bokmål",
					"nl_NL" => "Dutch",
					"pl_PL" => "Polski",
					"ru_RU" => "Русский",
					"pt_BR" => "Portuguese/Brazil",
					"pt_PT" => "Portuguese/Portugal",
					"zh_CN" => "Simplified Chinese",
					"zh_TW" => "Traditional Chinese",
					"sv_SE" => "Svenska",
					"fi_FI" => "Suomi",
					"tr_TR" => "Türkçe");

		return $tr;
	}

	require_once "lib/accept-to-gettext.php";
	require_once "lib/gettext/gettext.inc";

	function startup_gettext() {

		# Get locale from Accept-Language header
		$lang = al2gt(array_keys(get_translations()), "text/html");

		if (defined('_TRANSLATION_OVERRIDE_DEFAULT')) {
			$lang = _TRANSLATION_OVERRIDE_DEFAULT;
		}

		if ($_SESSION["uid"] && get_schema_version() >= 120) {
			$pref_lang = get_pref("USER_LANGUAGE", $_SESSION["uid"]);

			if ($pref_lang && $pref_lang != 'auto') {
				$lang = $pref_lang;
			}
		}

		if ($lang) {
			if (defined('LC_MESSAGES')) {
				_setlocale(LC_MESSAGES, $lang);
			} else if (defined('LC_ALL')) {
				_setlocale(LC_ALL, $lang);
			}

			_bindtextdomain("messages", "locale");

			_textdomain("messages");
			_bind_textdomain_codeset("messages", "UTF-8");
		}
	}

	require_once 'db-prefs.php';
	require_once 'version.php';
	require_once 'controls.php';

	define('SELF_USER_AGENT', 'Tiny Tiny RSS/' . VERSION . ' (http://tt-rss.org/)');
	ini_set('user_agent', SELF_USER_AGENT);

	$schema_version = false;

	function _debug_suppress($suppress) {
		global $suppress_debugging;

		$suppress_debugging = $suppress;
	}

	/**
	 * Print a timestamped debug message.
	 *
	 * @param string $msg The debug message.
	 * @return void
	 */
	function _debug($msg, $show = true) {
		global $suppress_debugging;

		//echo "[$suppress_debugging] $msg $show\n";

		if ($suppress_debugging) return false;

		$ts = strftime("%H:%M:%S", time());
		if (function_exists('posix_getpid')) {
			$ts = "$ts/" . posix_getpid();
		}

		if ($show && !(defined('QUIET') && QUIET)) {
			print "[$ts] $msg\n";
		}

		if (defined('LOGFILE'))  {
			$fp = fopen(LOGFILE, 'a+');

			if ($fp) {
				$locked = false;

				if (function_exists("flock")) {
					$tries = 0;

					// try to lock logfile for writing
					while ($tries < 5 && !$locked = flock($fp, LOCK_EX | LOCK_NB)) {
						sleep(1);
						++$tries;
					}

					if (!$locked) {
						fclose($fp);
						return;
					}
				}

				fputs($fp, "[$ts] $msg\n");

				if (function_exists("flock")) {
					flock($fp, LOCK_UN);
				}

				fclose($fp);
			}
		}

	} // function _debug

	/**
	 * Purge a feed old posts.
	 *
	 * @param mixed $link A database connection.
	 * @param mixed $feed_id The id of the purged feed.
	 * @param mixed $purge_interval Olderness of purged posts.
	 * @param boolean $debug Set to True to enable the debug. False by default.
	 * @access public
	 * @return void
	 */
	function purge_feed($feed_id, $purge_interval, $debug = false) {

		if (!$purge_interval) $purge_interval = feed_purge_interval($feed_id);

		$pdo = Db::pdo();

		$sth = $pdo->prepare("SELECT owner_uid FROM ttrss_feeds WHERE id = ?");
		$sth->execute([$feed_id]);

		$owner_uid = false;

		if ($row = $sth->fetch()) {
			$owner_uid = $row["owner_uid"];
		}

		if ($purge_interval == -1 || !$purge_interval) {
			if ($owner_uid) {
				CCache::update($feed_id, $owner_uid);
			}
			return;
		}

		if (!$owner_uid) return;

		if (FORCE_ARTICLE_PURGE == 0) {
			$purge_unread = get_pref("PURGE_UNREAD_ARTICLES",
				$owner_uid, false);
		} else {
			$purge_unread = true;
			$purge_interval = FORCE_ARTICLE_PURGE;
		}

		if (!$purge_unread)
			$query_limit = " unread = false AND ";
		else
			$query_limit = "";

		$purge_interval = (int) $purge_interval;

		if (DB_TYPE == "pgsql") {
			$sth = $pdo->prepare("DELETE FROM ttrss_user_entries
				USING ttrss_entries
				WHERE ttrss_entries.id = ref_id AND
				marked = false AND
				feed_id = ? AND
				$query_limit
				ttrss_entries.date_updated < NOW() - INTERVAL '$purge_interval days'");
			$sth->execute([$feed_id]);

		} else {
			$sth  = $pdo->prepare("DELETE FROM ttrss_user_entries
				USING ttrss_user_entries, ttrss_entries
				WHERE ttrss_entries.id = ref_id AND
				marked = false AND
				feed_id = ? AND
				$query_limit
				ttrss_entries.date_updated < DATE_SUB(NOW(), INTERVAL $purge_interval DAY)");
			$sth->execute([$feed_id]);

		}

		$rows = $sth->rowCount();

		CCache::update($feed_id, $owner_uid);

		if ($debug) {
			_debug("Purged feed $feed_id ($purge_interval): deleted $rows articles");
		}

		return $rows;
	} // function purge_feed

	function feed_purge_interval($feed_id) {

		$pdo = DB::pdo();

		$sth = $pdo->prepare("SELECT purge_interval, owner_uid FROM ttrss_feeds
			WHERE id = ?");
		$sth->execute([$feed_id]);

		if ($row = $sth->fetch()) {
			$purge_interval = $row["purge_interval"];
			$owner_uid = $row["owner_uid"];

			if ($purge_interval == 0) $purge_interval = get_pref(
				'PURGE_OLD_DAYS', $owner_uid);

			return $purge_interval;

		} else {
			return -1;
		}
	}

	// TODO: max_size currently only works for CURL transfers
	// TODO: multiple-argument way is deprecated, first parameter is a hash now
	function fetch_file_contents($options /* previously: 0: $url , 1: $type = false, 2: $login = false, 3: $pass = false,
				4: $post_query = false, 5: $timeout = false, 6: $timestamp = 0, 7: $useragent = false*/) {

		global $fetch_last_error;
		global $fetch_last_error_code;
		global $fetch_last_error_content;
		global $fetch_last_content_type;
		global $fetch_last_modified;
		global $fetch_effective_url;
		global $fetch_curl_used;

		$fetch_last_error = false;
		$fetch_last_error_code = -1;
		$fetch_last_error_content = "";
		$fetch_last_content_type = "";
		$fetch_curl_used = false;
		$fetch_last_modified = "";
		$fetch_effective_url = "";

		if (!is_array($options)) {

			// falling back on compatibility shim
			$option_names = [ "url", "type", "login", "pass", "post_query", "timeout", "last_modified", "useragent" ];
			$tmp = [];

			for ($i = 0; $i < func_num_args(); $i++) {
				$tmp[$option_names[$i]] = func_get_arg($i);
			}

			$options = $tmp;

			/*$options = array(
					"url" => func_get_arg(0),
					"type" => @func_get_arg(1),
					"login" => @func_get_arg(2),
					"pass" => @func_get_arg(3),
					"post_query" => @func_get_arg(4),
					"timeout" => @func_get_arg(5),
					"timestamp" => @func_get_arg(6),
					"useragent" => @func_get_arg(7)
			); */
		}

		$url = $options["url"];
		$type = isset($options["type"]) ? $options["type"] : false;
		$login = isset($options["login"]) ? $options["login"] : false;
		$pass = isset($options["pass"]) ? $options["pass"] : false;
		$post_query = isset($options["post_query"]) ? $options["post_query"] : false;
		$timeout = isset($options["timeout"]) ? $options["timeout"] : false;
		$last_modified = isset($options["last_modified"]) ? $options["last_modified"] : "";
		$useragent = isset($options["useragent"]) ? $options["useragent"] : false;
		$followlocation = isset($options["followlocation"]) ? $options["followlocation"] : true;
		$max_size = isset($options["max_size"]) ? $options["max_size"] : MAX_DOWNLOAD_FILE_SIZE; // in bytes
		$http_accept = isset($options["http_accept"]) ? $options["http_accept"] : false;

		$url = ltrim($url, ' ');
		$url = str_replace(' ', '%20', $url);

		if (strpos($url, "//") === 0)
			$url = 'http:' . $url;

		if (!defined('NO_CURL') && function_exists('curl_init') && !ini_get("open_basedir")) {

			$fetch_curl_used = true;

			$ch = curl_init($url);

			$curl_http_headers = [];

			if ($last_modified && !$post_query)
				array_push($curl_http_headers, "If-Modified-Since: $last_modified");

			if ($http_accept)
				array_push($curl_http_headers, "Accept: " . $http_accept);

			if (count($curl_http_headers) > 0)
				curl_setopt($ch, CURLOPT_HTTPHEADER, $curl_http_headers);

			curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $timeout ? $timeout : FILE_FETCH_CONNECT_TIMEOUT);
			curl_setopt($ch, CURLOPT_TIMEOUT, $timeout ? $timeout : FILE_FETCH_TIMEOUT);
			curl_setopt($ch, CURLOPT_FOLLOWLOCATION, !ini_get("open_basedir") && $followlocation);
			curl_setopt($ch, CURLOPT_MAXREDIRS, 20);
			curl_setopt($ch, CURLOPT_BINARYTRANSFER, true);
			curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
			curl_setopt($ch, CURLOPT_HEADER, true);
			curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
			curl_setopt($ch, CURLOPT_USERAGENT, $useragent ? $useragent :
				SELF_USER_AGENT);
			curl_setopt($ch, CURLOPT_ENCODING, "");
			//curl_setopt($ch, CURLOPT_REFERER, $url);

			if ($max_size) {
				curl_setopt($ch, CURLOPT_NOPROGRESS, false);
				curl_setopt($ch, CURLOPT_BUFFERSIZE, 16384); // needed to get 5 arguments in progress function?

				// holy shit closures in php
				// download & upload are *expected* sizes respectively, could be zero
				curl_setopt($ch, CURLOPT_PROGRESSFUNCTION, function($curl_handle, $download_size, $downloaded, $upload_size, $uploaded) use( &$max_size) {
					//_debug("[curl progressfunction] $downloaded $max_size");

					return ($downloaded > $max_size) ? 1 : 0; // if max size is set, abort when exceeding it
				});

			}

			if (!ini_get("open_basedir")) {
				curl_setopt($ch, CURLOPT_COOKIEJAR, "/dev/null");
			}

			if (defined('_HTTP_PROXY')) {
				curl_setopt($ch, CURLOPT_PROXY, _HTTP_PROXY);
			}

			if ($post_query) {
				curl_setopt($ch, CURLOPT_POST, true);
				curl_setopt($ch, CURLOPT_POSTFIELDS, $post_query);
			}

			if ($login && $pass)
				curl_setopt($ch, CURLOPT_USERPWD, "$login:$pass");

			$ret = @curl_exec($ch);

			$headers_length = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
			$headers = explode("\r\n", substr($ret, 0, $headers_length));
			$contents = substr($ret, $headers_length);

			foreach ($headers as $header) {
				if (strstr($header, ": ") !== FALSE) {
					list ($key, $value) = explode(": ", $header);

					if (strtolower($key) == "last-modified") {
						$fetch_last_modified = $value;
					}
				}

				if (substr(strtolower($header), 0, 7) == 'http/1.') {
					$fetch_last_error_code = (int) substr($header, 9, 3);
					$fetch_last_error = $header;
				}
			}

			if (curl_errno($ch) === 23 || curl_errno($ch) === 61) {
				curl_setopt($ch, CURLOPT_ENCODING, 'none');
				$contents = @curl_exec($ch);
			}

			$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
			$fetch_last_content_type = curl_getinfo($ch, CURLINFO_CONTENT_TYPE);

			$fetch_effective_url = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);

			$fetch_last_error_code = $http_code;

			if ($http_code != 200 || $type && strpos($fetch_last_content_type, "$type") === false) {

				if (curl_errno($ch) != 0) {
					$fetch_last_error .=  "; " . curl_errno($ch) . " " . curl_error($ch);
				}

				$fetch_last_error_content = $contents;
				curl_close($ch);
				return false;
			}

			if (!$contents) {
				$fetch_last_error = curl_errno($ch) . " " . curl_error($ch);
				curl_close($ch);
				return false;
			}

			curl_close($ch);

			return $contents;
		} else {

			$fetch_curl_used = false;

			if ($login && $pass){
				$url_parts = array();

				preg_match("/(^[^:]*):\/\/(.*)/", $url, $url_parts);

				$pass = urlencode($pass);

				if ($url_parts[1] && $url_parts[2]) {
					$url = $url_parts[1] . "://$login:$pass@" . $url_parts[2];
				}
			}

			// TODO: should this support POST requests or not? idk

			 $context_options = array(
				  'http' => array(
						'header' => array(
							'Connection: close'
						),
						'method' => 'GET',
						'ignore_errors' => true,
						'timeout' => $timeout ? $timeout : FILE_FETCH_TIMEOUT,
						'protocol_version'=> 1.1)
				  );

			if (!$post_query && $last_modified)
				array_push($context_options['http']['header'], "If-Modified-Since: $last_modified");

			if ($http_accept)
				array_push($context_options['http']['header'], "Accept: $http_accept");

			if (defined('_HTTP_PROXY')) {
				$context_options['http']['request_fulluri'] = true;
				$context_options['http']['proxy'] = _HTTP_PROXY;
			}

			$context = stream_context_create($context_options);

			$old_error = error_get_last();

			$fetch_effective_url = $url;

			$data = @file_get_contents($url, false, $context);

			if (isset($http_response_header) && is_array($http_response_header)) {
				foreach ($http_response_header as $header) {
					if (strstr($header, ": ") !== FALSE) {
						list ($key, $value) = explode(": ", $header);

						$key = strtolower($key);

						if ($key == 'content-type') {
							$fetch_last_content_type = $value;
							// don't abort here b/c there might be more than one
							// e.g. if we were being redirected -- last one is the right one
						} else if ($key == 'last-modified') {
							$fetch_last_modified = $value;
						} else if ($key == 'location') {
							$fetch_effective_url = $value;
						}
					}

					if (substr(strtolower($header), 0, 7) == 'http/1.') {
						$fetch_last_error_code = (int) substr($header, 9, 3);
						$fetch_last_error = $header;
					}
				}
			}

			if ($fetch_last_error_code != 200) {
				$error = error_get_last();

				if ($error['message'] != $old_error['message']) {
					$fetch_last_error .= "; " . $error["message"];
				}

				$fetch_last_error_content = $data;

				return false;
			}
			return $data;
		}

	}

	/**
	 * Try to determine the favicon URL for a feed.
	 * adapted from wordpress favicon plugin by Jeff Minard (http://thecodepro.com/)
	 * http://dev.wp-plugins.org/file/favatars/trunk/favatars.php
	 *
	 * @param string $url A feed or page URL
	 * @access public
	 * @return mixed The favicon URL, or false if none was found.
	 */
	function get_favicon_url($url) {

		$favicon_url = false;

		if ($html = @fetch_file_contents($url)) {

			libxml_use_internal_errors(true);

			$doc = new DOMDocument();
			$doc->loadHTML($html);
			$xpath = new DOMXPath($doc);

			$base = $xpath->query('/html/head/base[@href]');
			foreach ($base as $b) {
				$url = rewrite_relative_url($url, $b->getAttribute("href"));
				break;
			}

			$entries = $xpath->query('/html/head/link[@rel="shortcut icon" or @rel="icon"]');
			if (count($entries) > 0) {
				foreach ($entries as $entry) {
					$favicon_url = rewrite_relative_url($url, $entry->getAttribute("href"));
					break;
				}
			}
		}

		if (!$favicon_url)
			$favicon_url = rewrite_relative_url($url, "/favicon.ico");

		return $favicon_url;
	} // function get_favicon_url

	function initialize_user_prefs($uid, $profile = false) {

		if (get_schema_version() < 63) $profile_qpart = "";

		$pdo = DB::pdo();
		$in_nested_tr = false;

		try {
			$pdo->beginTransaction();
		} catch (Exception $e) {
			$in_nested_tr = true;
		}

		$sth = $pdo->query("SELECT pref_name,def_value FROM ttrss_prefs");

		$profile = $profile ? $profile : null;

		$u_sth = $pdo->prepare("SELECT pref_name
			FROM ttrss_user_prefs WHERE owner_uid = :uid AND
				(profile = :profile OR (:profile IS NULL AND profile IS NULL))");
		$u_sth->execute([':uid' => $uid, ':profile' => $profile]);

		$active_prefs = array();

		while ($line = $u_sth->fetch()) {
			array_push($active_prefs, $line["pref_name"]);
		}

		while ($line = $sth->fetch()) {
			if (array_search($line["pref_name"], $active_prefs) === FALSE) {
//				print "adding " . $line["pref_name"] . "<br>";

				if (get_schema_version() < 63) {
					$i_sth = $pdo->prepare("INSERT INTO ttrss_user_prefs
						(owner_uid,pref_name,value) VALUES
						(?, ?, ?)");
					$i_sth->execute([$uid, $line["pref_name"], $line["def_value"]]);

				} else {
					$i_sth = $pdo->prepare("INSERT INTO ttrss_user_prefs
						(owner_uid,pref_name,value, profile) VALUES
						(?, ?, ?, ?)");
					$i_sth->execute([$uid, $line["pref_name"], $line["def_value"], $profile]);
				}

			}
		}

		if (!$in_nested_tr) $pdo->commit();

	}

	function get_ssl_certificate_id() {
		if ($_SERVER["REDIRECT_SSL_CLIENT_M_SERIAL"]) {
			return sha1($_SERVER["REDIRECT_SSL_CLIENT_M_SERIAL"] .
				$_SERVER["REDIRECT_SSL_CLIENT_V_START"] .
				$_SERVER["REDIRECT_SSL_CLIENT_V_END"] .
				$_SERVER["REDIRECT_SSL_CLIENT_S_DN"]);
		}
		if ($_SERVER["SSL_CLIENT_M_SERIAL"]) {
			return sha1($_SERVER["SSL_CLIENT_M_SERIAL"] .
				$_SERVER["SSL_CLIENT_V_START"] .
				$_SERVER["SSL_CLIENT_V_END"] .
				$_SERVER["SSL_CLIENT_S_DN"]);
		}
		return "";
	}

	function authenticate_user($login, $password, $check_only = false) {

		if (!SINGLE_USER_MODE) {
			$user_id = false;
			$auth_module = false;

			foreach (PluginHost::getInstance()->get_hooks(PluginHost::HOOK_AUTH_USER) as $plugin) {

				$user_id = (int) $plugin->authenticate($login, $password);

				if ($user_id) {
					$auth_module = strtolower(get_class($plugin));
					break;
				}
			}

			if ($user_id && !$check_only) {

				/* if a session is started here there's a stale login cookie we need to clean */

				if (session_status() != PHP_SESSION_NONE) {
					$_SESSION["login_error_msg"] = __("Stale session cookie found, try logging in again");
					return false;
				}

				session_regenerate_id(true);
				session_start();

				$_SESSION["uid"] = $user_id;
				$_SESSION["version"] = VERSION_STATIC;
				$_SESSION["auth_module"] = $auth_module;

				$pdo = DB::pdo();
				$sth = $pdo->prepare("SELECT login,access_level,pwd_hash FROM ttrss_users
					WHERE id = ?");
				$sth->execute([$user_id]);
				$row = $sth->fetch();

				$_SESSION["name"] = $row["login"];
				$_SESSION["access_level"] = $row["access_level"];
				$_SESSION["csrf_token"] = uniqid_short();

				$usth = $pdo->prepare("UPDATE ttrss_users SET last_login = NOW() WHERE id = ?");
				$usth->execute([$user_id]);

				$_SESSION["ip_address"] = $_SERVER["REMOTE_ADDR"];
				$_SESSION["user_agent"] = sha1($_SERVER['HTTP_USER_AGENT']);
				$_SESSION["pwd_hash"] = $row["pwd_hash"];

				$_SESSION["last_version_check"] = time();

				initialize_user_prefs($_SESSION["uid"]);

				return true;
			}

			return false;

		} else {

			$_SESSION["uid"] = 1;
			$_SESSION["name"] = "admin";
			$_SESSION["access_level"] = 10;

			$_SESSION["hide_hello"] = true;
			$_SESSION["hide_logout"] = true;

			$_SESSION["auth_module"] = false;

			if (!$_SESSION["csrf_token"]) {
				$_SESSION["csrf_token"] = uniqid_short();
			}

			$_SESSION["ip_address"] = $_SERVER["REMOTE_ADDR"];

			initialize_user_prefs($_SESSION["uid"]);

			return true;
		}
	}

	// this is used for user http parameters unless HTML code is actually needed
	function clean($param) {
		if (is_array($param)) {
			return array_map("strip_tags", $param);
		} else if (is_string($param)) {
			return strip_tags($param);
		} else {
			return $param;
		}
	}

	function make_password($length = 8) {

		$password = "";
		$possible = "0123456789abcdfghjkmnpqrstvwxyzABCDFGHJKMNPQRSTVWXYZ";

	$i = 0;

		while ($i < $length) {
			$char = substr($possible, mt_rand(0, strlen($possible)-1), 1);

			if (!strstr($password, $char)) {
				$password .= $char;
				$i++;
			}
		}
		return $password;
	}

	// this is called after user is created to initialize default feeds, labels
	// or whatever else

	// user preferences are checked on every login, not here

	function initialize_user($uid) {

		$pdo = DB::pdo();

		$sth = $pdo->prepare("insert into ttrss_feeds (owner_uid,title,feed_url)
			values (?, 'Tiny Tiny RSS: Forum',
				'http://tt-rss.org/forum/rss.php')");
		$sth->execute([$uid]);
	}

	function logout_user() {
		@session_destroy();
		if (isset($_COOKIE[session_name()])) {
		   setcookie(session_name(), '', time()-42000, '/');
		}
		session_commit();
	}

	function validate_csrf($csrf_token) {
		return $csrf_token == $_SESSION['csrf_token'];
	}

	function load_user_plugins($owner_uid, $pluginhost = false) {

		if (!$pluginhost) $pluginhost = PluginHost::getInstance();

		if ($owner_uid && SCHEMA_VERSION >= 100) {
			$plugins = get_pref("_ENABLED_PLUGINS", $owner_uid);

			$pluginhost->load($plugins, PluginHost::KIND_USER, $owner_uid);

			if (get_schema_version() > 100) {
				$pluginhost->load_data();
			}
		}
	}

	function login_sequence() {
		$pdo = Db::pdo();

		if (SINGLE_USER_MODE) {
			@session_start();
			authenticate_user("admin", null);
			startup_gettext();
			load_user_plugins($_SESSION["uid"]);
		} else {
			if (!validate_session()) $_SESSION["uid"] = false;

			if (!$_SESSION["uid"]) {

				if (AUTH_AUTO_LOGIN && authenticate_user(null, null)) {
					$_SESSION["ref_schema_version"] = get_schema_version(true);
				} else {
					 authenticate_user(null, null, true);
				}

				if (!$_SESSION["uid"]) {
					logout_user();

					render_login_form();
					exit;
				}

			} else {
				/* bump login timestamp */
				$sth = $pdo->prepare("UPDATE ttrss_users SET last_login = NOW() WHERE id = ?");
				$sth->execute([$_SESSION['uid']]);

				$_SESSION["last_login_update"] = time();
			}

			if ($_SESSION["uid"]) {
				startup_gettext();
				load_user_plugins($_SESSION["uid"]);

				/* cleanup ccache */

				$sth = $pdo->prepare("DELETE FROM ttrss_counters_cache WHERE owner_uid = ?
					AND
						(SELECT COUNT(id) FROM ttrss_feeds WHERE
							ttrss_feeds.id = feed_id) = 0");

				$sth->execute([$_SESSION['uid']]);

				$sth = $pdo->prepare("DELETE FROM ttrss_cat_counters_cache WHERE owner_uid = ?
					AND
						(SELECT COUNT(id) FROM ttrss_feed_categories WHERE
							ttrss_feed_categories.id = feed_id) = 0");

				$sth->execute([$_SESSION['uid']]);
			}

		}
	}

	function truncate_string($str, $max_len, $suffix = '&hellip;') {
		if (mb_strlen($str, "utf-8") > $max_len) {
			return mb_substr($str, 0, $max_len, "utf-8") . $suffix;
		} else {
			return $str;
		}
	}

	// is not utf8 clean
	function truncate_middle($str, $max_len, $suffix = '&hellip;') {
		if (strlen($str) > $max_len) {
			return substr_replace($str, $suffix, $max_len / 2, mb_strlen($str) - $max_len);
		} else {
			return $str;
		}
	}

	function convert_timestamp($timestamp, $source_tz, $dest_tz) {

		try {
			$source_tz = new DateTimeZone($source_tz);
		} catch (Exception $e) {
			$source_tz = new DateTimeZone('UTC');
		}

		try {
			$dest_tz = new DateTimeZone($dest_tz);
		} catch (Exception $e) {
			$dest_tz = new DateTimeZone('UTC');
		}

		$dt = new DateTime(date('Y-m-d H:i:s', $timestamp), $source_tz);
		return $dt->format('U') + $dest_tz->getOffset($dt);
	}

	function make_local_datetime($timestamp, $long, $owner_uid = false,
					$no_smart_dt = false, $eta_min = false) {

		if (!$owner_uid) $owner_uid = $_SESSION['uid'];
		if (!$timestamp) $timestamp = '1970-01-01 0:00';

		global $utc_tz;
		global $user_tz;

		if (!$utc_tz) $utc_tz = new DateTimeZone('UTC');

		$timestamp = substr($timestamp, 0, 19);

		# We store date in UTC internally
		$dt = new DateTime($timestamp, $utc_tz);

		$user_tz_string = get_pref('USER_TIMEZONE', $owner_uid);

		if ($user_tz_string != 'Automatic') {

			try {
				if (!$user_tz) $user_tz = new DateTimeZone($user_tz_string);
			} catch (Exception $e) {
				$user_tz = $utc_tz;
			}

			$tz_offset = $user_tz->getOffset($dt);
		} else {
			$tz_offset = (int) -$_SESSION["clientTzOffset"];
		}

		$user_timestamp = $dt->format('U') + $tz_offset;

		if (!$no_smart_dt) {
			return smart_date_time($user_timestamp,
				$tz_offset, $owner_uid, $eta_min);
		} else {
			if ($long)
				$format = get_pref('LONG_DATE_FORMAT', $owner_uid);
			else
				$format = get_pref('SHORT_DATE_FORMAT', $owner_uid);

			return date($format, $user_timestamp);
		}
	}

	function smart_date_time($timestamp, $tz_offset = 0, $owner_uid = false, $eta_min = false) {
		if (!$owner_uid) $owner_uid = $_SESSION['uid'];

		if ($eta_min && time() + $tz_offset - $timestamp < 3600) {
			return T_sprintf("%d min", date("i", time() + $tz_offset - $timestamp));
		} else if (date("Y.m.d", $timestamp) == date("Y.m.d", time() + $tz_offset)) {
			return date("G:i", $timestamp);
		} else if (date("Y", $timestamp) == date("Y", time() + $tz_offset)) {
			$format = get_pref('SHORT_DATE_FORMAT', $owner_uid);
			return date($format, $timestamp);
		} else {
			$format = get_pref('LONG_DATE_FORMAT', $owner_uid);
			return date($format, $timestamp);
		}
	}

	function sql_bool_to_bool($s) {
		return $s && ($s !== "f" && $s !== "false"); //no-op for PDO, backwards compat for legacy layer
	}

	function bool_to_sql_bool($s) {
		return $s ? 1 : 0;
	}

	// Session caching removed due to causing wrong redirects to upgrade
	// script when get_schema_version() is called on an obsolete session
	// created on a previous schema version.
	function get_schema_version($nocache = false) {
		global $schema_version;

		$pdo = DB::pdo();

		if (!$schema_version && !$nocache) {
			$row = $pdo->query("SELECT schema_version FROM ttrss_version")->fetch();
			$version = $row["schema_version"];
			$schema_version = $version;
			return $version;
		} else {
			return $schema_version;
		}
	}

	function sanity_check() {
		require_once 'errors.php';
		global $ERRORS;

		$error_code = 0;
		$schema_version = get_schema_version(true);

		if ($schema_version != SCHEMA_VERSION) {
			$error_code = 5;
		}

		return array("code" => $error_code, "message" => $ERRORS[$error_code]);
	}

	function file_is_locked($filename) {
		if (file_exists(LOCK_DIRECTORY . "/$filename")) {
			if (function_exists('flock')) {
				$fp = @fopen(LOCK_DIRECTORY . "/$filename", "r");
				if ($fp) {
					if (flock($fp, LOCK_EX | LOCK_NB)) {
						flock($fp, LOCK_UN);
						fclose($fp);
						return false;
					}
					fclose($fp);
					return true;
				} else {
					return false;
				}
			}
			return true; // consider the file always locked and skip the test
		} else {
			return false;
		}
	}


	function make_lockfile($filename) {
		$fp = fopen(LOCK_DIRECTORY . "/$filename", "w");

		if ($fp && flock($fp, LOCK_EX | LOCK_NB)) {
			$stat_h = fstat($fp);
			$stat_f = stat(LOCK_DIRECTORY . "/$filename");

			if (strtoupper(substr(PHP_OS, 0, 3)) !== 'WIN') {
				if ($stat_h["ino"] != $stat_f["ino"] ||
						$stat_h["dev"] != $stat_f["dev"]) {

					return false;
				}
			}

			if (function_exists('posix_getpid')) {
				fwrite($fp, posix_getpid() . "\n");
			}
			return $fp;
		} else {
			return false;
		}
	}

	function make_stampfile($filename) {
		$fp = fopen(LOCK_DIRECTORY . "/$filename", "w");

		if (flock($fp, LOCK_EX | LOCK_NB)) {
			fwrite($fp, time() . "\n");
			flock($fp, LOCK_UN);
			fclose($fp);
			return true;
		} else {
			return false;
		}
	}

	function sql_random_function() {
		if (DB_TYPE == "mysql") {
			return "RAND()";
		} else {
			return "RANDOM()";
		}
	}

	function getFeedUnread($feed, $is_cat = false) {
		return Feeds::getFeedArticles($feed, $is_cat, true, $_SESSION["uid"]);
	}

	function checkbox_to_sql_bool($val) {
		return ($val == "on") ? 1 : 0;
	}

	function uniqid_short() {
		return uniqid(base_convert(rand(), 10, 36));
	}

	function make_init_params() {
		$params = array();

		foreach (array("ON_CATCHUP_SHOW_NEXT_FEED", "HIDE_READ_FEEDS",
					 "ENABLE_FEED_CATS", "FEEDS_SORT_BY_UNREAD", "CONFIRM_FEED_CATCHUP",
					 "CDM_AUTO_CATCHUP", "FRESH_ARTICLE_MAX_AGE",
					 "HIDE_READ_SHOWS_SPECIAL", "COMBINED_DISPLAY_MODE") as $param) {

			$params[strtolower($param)] = (int) get_pref($param);
		}

		$params["icons_url"] = ICONS_URL;
		$params["cookie_lifetime"] = SESSION_COOKIE_LIFETIME;
		$params["default_view_mode"] = get_pref("_DEFAULT_VIEW_MODE");
		$params["default_view_limit"] = (int) get_pref("_DEFAULT_VIEW_LIMIT");
		$params["default_view_order_by"] = get_pref("_DEFAULT_VIEW_ORDER_BY");
		$params["bw_limit"] = (int) $_SESSION["bw_limit"];
		$params["is_default_pw"] = Pref_Prefs::isdefaultpassword();
		$params["label_base_index"] = (int) LABEL_BASE_INDEX;

		$theme = get_pref( "USER_CSS_THEME", false, false);
		$params["theme"] = theme_valid("$theme") ? $theme : "";

		$params["plugins"] = implode(", ", PluginHost::getInstance()->get_plugin_names());

		$params["php_platform"] = PHP_OS;
		$params["php_version"] = PHP_VERSION;

		$params["sanity_checksum"] = sha1(file_get_contents("include/sanity_check.php"));

		$pdo = Db::pdo();

		$sth = $pdo->prepare("SELECT MAX(id) AS mid, COUNT(*) AS nf FROM
				ttrss_feeds WHERE owner_uid = ?");
		$sth->execute([$_SESSION['uid']]);
		$row = $sth->fetch();

		$max_feed_id = $row["mid"];
		$num_feeds = $row["nf"];

		$params["max_feed_id"] = (int) $max_feed_id;
		$params["num_feeds"] = (int) $num_feeds;

		$params["hotkeys"] = get_hotkeys_map();

		$params["csrf_token"] = $_SESSION["csrf_token"];
		$params["widescreen"] = (int) $_COOKIE["ttrss_widescreen"];

		$params['simple_update'] = defined('SIMPLE_UPDATE_MODE') && SIMPLE_UPDATE_MODE;

		$params["icon_alert"] = base64_img("images/alert.png");
		$params["icon_information"] = base64_img("images/information.png");
		$params["icon_cross"] = base64_img("images/cross.png");
		$params["icon_indicator_white"] = base64_img("images/indicator_white.gif");

		$params["labels"] = Labels::get_all_labels($_SESSION["uid"]);

		return $params;
	}

	function get_hotkeys_info() {
		$hotkeys = array(
			__("Navigation") => array(
				"next_feed" => __("Open next feed"),
				"prev_feed" => __("Open previous feed"),
				"next_article" => __("Open next article"),
				"prev_article" => __("Open previous article"),
				"next_article_noscroll" => __("Open next article (don't scroll long articles)"),
				"prev_article_noscroll" => __("Open previous article (don't scroll long articles)"),
				"next_article_noexpand" => __("Move to next article (don't expand or mark read)"),
				"prev_article_noexpand" => __("Move to previous article (don't expand or mark read)"),
				"search_dialog" => __("Show search dialog")),
			__("Article") => array(
				"toggle_mark" => __("Toggle starred"),
				"toggle_publ" => __("Toggle published"),
				"toggle_unread" => __("Toggle unread"),
				"edit_tags" => __("Edit tags"),
				"open_in_new_window" => __("Open in new window"),
				"catchup_below" => __("Mark below as read"),
				"catchup_above" => __("Mark above as read"),
				"article_scroll_down" => __("Scroll down"),
				"article_scroll_up" => __("Scroll up"),
				"select_article_cursor" => __("Select article under cursor"),
				"email_article" => __("Email article"),
				"close_article" => __("Close/collapse article"),
				"toggle_expand" => __("Toggle article expansion (combined mode)"),
				"toggle_widescreen" => __("Toggle widescreen mode"),
				"toggle_embed_original" => __("Toggle embed original")),
			__("Article selection") => array(
				"select_all" => __("Select all articles"),
				"select_unread" => __("Select unread"),
				"select_marked" => __("Select starred"),
				"select_published" => __("Select published"),
				"select_invert" => __("Invert selection"),
				"select_none" => __("Deselect everything")),
			__("Feed") => array(
				"feed_refresh" => __("Refresh current feed"),
				"feed_unhide_read" => __("Un/hide read feeds"),
				"feed_subscribe" => __("Subscribe to feed"),
				"feed_edit" => __("Edit feed"),
				"feed_catchup" => __("Mark as read"),
				"feed_reverse" => __("Reverse headlines"),
				"feed_toggle_vgroup" => __("Toggle headline grouping"),
				"feed_debug_update" => __("Debug feed update"),
				"feed_debug_viewfeed" => __("Debug viewfeed()"),
				"catchup_all" => __("Mark all feeds as read"),
				"cat_toggle_collapse" => __("Un/collapse current category"),
				"toggle_combined_mode" => __("Toggle combined mode"),
				"toggle_cdm_expanded" => __("Toggle auto expand in combined mode")),
			__("Go to") => array(
				"goto_all" => __("All articles"),
				"goto_fresh" => __("Fresh"),
				"goto_marked" => __("Starred"),
				"goto_published" => __("Published"),
				"goto_tagcloud" => __("Tag cloud"),
				"goto_prefs" => __("Preferences")),
			__("Other") => array(
				"create_label" => __("Create label"),
				"create_filter" => __("Create filter"),
				"collapse_sidebar" => __("Un/collapse sidebar"),
				"help_dialog" => __("Show help dialog"))
		);

		foreach (PluginHost::getInstance()->get_hooks(PluginHost::HOOK_HOTKEY_INFO) as $plugin) {
			$hotkeys = $plugin->hook_hotkey_info($hotkeys);
		}

		return $hotkeys;
	}

	function get_hotkeys_map() {
		$hotkeys = array(
	//			"navigation" => array(
			"k" => "next_feed",
			"j" => "prev_feed",
			"n" => "next_article",
			"p" => "prev_article",
			"(38)|up" => "prev_article",
			"(40)|down" => "next_article",
	//				"^(38)|Ctrl-up" => "prev_article_noscroll",
	//				"^(40)|Ctrl-down" => "next_article_noscroll",
			"(191)|/" => "search_dialog",
	//			"article" => array(
			"s" => "toggle_mark",
			"*s" => "toggle_publ",
			"u" => "toggle_unread",
			"*t" => "edit_tags",
			"o" => "open_in_new_window",
			"c p" => "catchup_below",
			"c n" => "catchup_above",
			"*n" => "article_scroll_down",
			"*p" => "article_scroll_up",
			"*(38)|Shift+up" => "article_scroll_up",
			"*(40)|Shift+down" => "article_scroll_down",
			"a *w" => "toggle_widescreen",
			"a e" => "toggle_embed_original",
			"e" => "email_article",
			"a q" => "close_article",
	//			"article_selection" => array(
			"a a" => "select_all",
			"a u" => "select_unread",
			"a *u" => "select_marked",
			"a p" => "select_published",
			"a i" => "select_invert",
			"a n" => "select_none",
	//			"feed" => array(
			"f r" => "feed_refresh",
			"f a" => "feed_unhide_read",
			"f s" => "feed_subscribe",
			"f e" => "feed_edit",
			"f q" => "feed_catchup",
			"f x" => "feed_reverse",
			"f g" => "feed_toggle_vgroup",
			"f *d" => "feed_debug_update",
			"f *g" => "feed_debug_viewfeed",
			"f *c" => "toggle_combined_mode",
			"f c" => "toggle_cdm_expanded",
			"*q" => "catchup_all",
			"x" => "cat_toggle_collapse",
	//			"goto" => array(
			"g a" => "goto_all",
			"g f" => "goto_fresh",
			"g s" => "goto_marked",
			"g p" => "goto_published",
			"g t" => "goto_tagcloud",
			"g *p" => "goto_prefs",
	//			"other" => array(
			"(9)|Tab" => "select_article_cursor", // tab
			"c l" => "create_label",
			"c f" => "create_filter",
			"c s" => "collapse_sidebar",
			"^(191)|Ctrl+/" => "help_dialog",
		);

		if (get_pref('COMBINED_DISPLAY_MODE')) {
			$hotkeys["^(38)|Ctrl-up"] = "prev_article_noscroll";
			$hotkeys["^(40)|Ctrl-down"] = "next_article_noscroll";
		}

		foreach (PluginHost::getInstance()->get_hooks(PluginHost::HOOK_HOTKEY_MAP) as $plugin) {
			$hotkeys = $plugin->hook_hotkey_map($hotkeys);
		}

		$prefixes = array();

		foreach (array_keys($hotkeys) as $hotkey) {
			$pair = explode(" ", $hotkey, 2);

			if (count($pair) > 1 && !in_array($pair[0], $prefixes)) {
				array_push($prefixes, $pair[0]);
			}
		}

		return array($prefixes, $hotkeys);
	}

	function check_for_update() {
		if (defined("GIT_VERSION_TIMESTAMP")) {
			$content = @fetch_file_contents(array("url" => "http://tt-rss.org/version.json", "timeout" => 5));

			if ($content) {
				$content = json_decode($content, true);

				if ($content && isset($content["changeset"])) {
					if ((int)GIT_VERSION_TIMESTAMP < (int)$content["changeset"]["timestamp"] &&
						GIT_VERSION_HEAD != $content["changeset"]["id"]) {

						return $content["changeset"]["id"];
					}
				}
			}
		}

		return "";
	}

	function make_runtime_info($disable_update_check = false) {
		$data = array();

		$pdo = Db::pdo();

		$sth = $pdo->prepare("SELECT MAX(id) AS mid, COUNT(*) AS nf FROM
				ttrss_feeds WHERE owner_uid = ?");
		$sth->execute([$_SESSION['uid']]);
		$row = $sth->fetch();

		$max_feed_id = $row['mid'];
		$num_feeds = $row['nf'];

		$data["max_feed_id"] = (int) $max_feed_id;
		$data["num_feeds"] = (int) $num_feeds;

		$data['last_article_id'] = Article::getLastArticleId();
		$data['cdm_expanded'] = get_pref('CDM_EXPANDED');

		$data['dep_ts'] = calculate_dep_timestamp();
		$data['reload_on_ts_change'] = !defined('_NO_RELOAD_ON_TS_CHANGE');

		$data["labels"] = Labels::get_all_labels($_SESSION["uid"]);

		if (CHECK_FOR_UPDATES && !$disable_update_check && $_SESSION["last_version_check"] + 86400 + rand(-1000, 1000) < time()) {
			$update_result = @check_for_update();

			$data["update_result"] = $update_result;

			$_SESSION["last_version_check"] = time();
		}

		if (file_exists(LOCK_DIRECTORY . "/update_daemon.lock")) {

			$data['daemon_is_running'] = (int) file_is_locked("update_daemon.lock");

			if (time() - $_SESSION["daemon_stamp_check"] > 30) {

				$stamp = (int) @file_get_contents(LOCK_DIRECTORY . "/update_daemon.stamp");

				if ($stamp) {
					$stamp_delta = time() - $stamp;

					if ($stamp_delta > 1800) {
						$stamp_check = 0;
					} else {
						$stamp_check = 1;
						$_SESSION["daemon_stamp_check"] = time();
					}

					$data['daemon_stamp_ok'] = $stamp_check;

					$stamp_fmt = date("Y.m.d, G:i", $stamp);

					$data['daemon_stamp'] = $stamp_fmt;
				}
			}
		}

		return $data;
	}

	function search_to_sql($search, $search_language) {

		$keywords = str_getcsv(trim($search), " ");
		$query_keywords = array();
		$search_words = array();
		$search_query_leftover = array();

		$pdo = Db::pdo();

		if ($search_language)
			$search_language = $pdo->quote(mb_strtolower($search_language));
		else
			$search_language = $pdo->quote("english");

		foreach ($keywords as $k) {
			if (strpos($k, "-") === 0) {
				$k = substr($k, 1);
				$not = "NOT";
			} else {
				$not = "";
			}

			$commandpair = explode(":", mb_strtolower($k), 2);

			switch ($commandpair[0]) {
				case "title":
					if ($commandpair[1]) {
						array_push($query_keywords, "($not (LOWER(ttrss_entries.title) LIKE ".
							$pdo->quote('%' . mb_strtolower($commandpair[1]) . '%') ."))");
					} else {
						array_push($query_keywords, "(UPPER(ttrss_entries.title) $not LIKE UPPER('%$k%')
								OR UPPER(ttrss_entries.content) $not LIKE UPPER(".$pdo->quote("%$k%")."))");
						array_push($search_words, $k);
					}
					break;
				case "author":
					if ($commandpair[1]) {
						array_push($query_keywords, "($not (LOWER(author) LIKE ".
							$pdo->quote('%' . mb_strtolower($commandpair[1]) . '%')."))");
					} else {
						array_push($query_keywords, "(UPPER(ttrss_entries.title) $not LIKE UPPER('%$k%')
								OR UPPER(ttrss_entries.content) $not LIKE UPPER(".$pdo->quote("%$k%")."))");
						array_push($search_words, $k);
					}
					break;
				case "note":
					if ($commandpair[1]) {
						if ($commandpair[1] == "true")
							array_push($query_keywords, "($not (note IS NOT NULL AND note != ''))");
						else if ($commandpair[1] == "false")
							array_push($query_keywords, "($not (note IS NULL OR note = ''))");
						else
							array_push($query_keywords, "($not (LOWER(note) LIKE ".
								$pdo->quote('%' . mb_strtolower($commandpair[1]) . '%')."))");
					} else {
						array_push($query_keywords, "(UPPER(ttrss_entries.title) $not LIKE UPPER(".$pdo->quote("%$k%").")
								OR UPPER(ttrss_entries.content) $not LIKE UPPER(".$pdo->quote("%$k%")."))");
						if (!$not) array_push($search_words, $k);
					}
					break;
				case "star":

					if ($commandpair[1]) {
						if ($commandpair[1] == "true")
							array_push($query_keywords, "($not (marked = true))");
						else
							array_push($query_keywords, "($not (marked = false))");
					} else {
						array_push($query_keywords, "(UPPER(ttrss_entries.title) $not LIKE UPPER(".$pdo->quote("%$k%").")
								OR UPPER(ttrss_entries.content) $not LIKE UPPER(".$pdo->quote("%$k%")."))");
						if (!$not) array_push($search_words, $k);
					}
					break;
				case "pub":
					if ($commandpair[1]) {
						if ($commandpair[1] == "true")
							array_push($query_keywords, "($not (published = true))");
						else
							array_push($query_keywords, "($not (published = false))");

					} else {
						array_push($query_keywords, "(UPPER(ttrss_entries.title) $not LIKE UPPER('%$k%')
								OR UPPER(ttrss_entries.content) $not LIKE UPPER(".$pdo->quote("%$k%")."))");
						if (!$not) array_push($search_words, $k);
					}
					break;
				case "unread":
					if ($commandpair[1]) {
						if ($commandpair[1] == "true")
							array_push($query_keywords, "($not (unread = true))");
						else
							array_push($query_keywords, "($not (unread = false))");

					} else {
						array_push($query_keywords, "(UPPER(ttrss_entries.title) $not LIKE UPPER(".$pdo->quote("%$k%").")
								OR UPPER(ttrss_entries.content) $not LIKE UPPER(".$pdo->quote("%$k%")."))");
						if (!$not) array_push($search_words, $k);
					}
					break;
				default:
					if (strpos($k, "@") === 0) {

						$user_tz_string = get_pref('USER_TIMEZONE', $_SESSION['uid']);
						$orig_ts = strtotime(substr($k, 1));
						$k = date("Y-m-d", convert_timestamp($orig_ts, $user_tz_string, 'UTC'));

						//$k = date("Y-m-d", strtotime(substr($k, 1)));

						array_push($query_keywords, "(".SUBSTRING_FOR_DATE."(updated,1,LENGTH('$k')) $not = '$k')");
					} else {

						if (DB_TYPE == "pgsql") {
							$k = mb_strtolower($k);
							array_push($search_query_leftover, $not ? "!$k" : $k);
						} else {
							array_push($query_keywords, "(UPPER(ttrss_entries.title) $not LIKE UPPER(".$pdo->quote("%$k%").")
								OR UPPER(ttrss_entries.content) $not LIKE UPPER(".$pdo->quote("%$k%")."))");
						}

						if (!$not) array_push($search_words, $k);
					}
			}
		}

		if (count($search_query_leftover) > 0) {
			$search_query_leftover = $pdo->quote(implode(" & ", $search_query_leftover));

			if (DB_TYPE == "pgsql") {
				array_push($query_keywords,
					"(tsvector_combined @@ to_tsquery($search_language, $search_query_leftover))");
			}

		}

		$search_query_part = implode("AND", $query_keywords);

		return array($search_query_part, $search_words);
	}

	function iframe_whitelisted($entry) {
		$whitelist = array("youtube.com", "youtu.be", "vimeo.com", "player.vimeo.com");

		@$src = parse_url($entry->getAttribute("src"), PHP_URL_HOST);

		if ($src) {
			foreach ($whitelist as $w) {
				if ($src == $w || $src == "www.$w")
					return true;
			}
		}

		return false;
	}

	// check for locally cached (media) URLs and rewrite to local versions
	// this is called separately after sanitize() and plugin render article hooks to allow
	// plugins work on original source URLs used before caching

	function rewrite_cached_urls($str) {
		$charset_hack = '<head>
				<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
			</head>';

		$res = trim($str); if (!$res) return '';

		$doc = new DOMDocument();
		$doc->loadHTML($charset_hack . $res);
		$xpath = new DOMXPath($doc);

		$entries = $xpath->query('(//img[@src]|//video[@poster]|//video/source[@src]|//audio/source[@src])');

		$need_saving = false;

		foreach ($entries as $entry) {

			if ($entry->hasAttribute('src') || $entry->hasAttribute('poster')) {

				// should be already absolutized because this is called after sanitize()
				$src = $entry->hasAttribute('poster') ? $entry->getAttribute('poster') : $entry->getAttribute('src');
				$cached_filename = CACHE_DIR . '/images/' . sha1($src);

				if (file_exists($cached_filename)) {

					// this is strictly cosmetic
					if ($entry->tagName == 'img') {
						$suffix = ".png";
					} else if ($entry->parentNode && $entry->parentNode->tagName == "video") {
						$suffix = ".mp4";
					} else if ($entry->parentNode && $entry->parentNode->tagName == "audio") {
						$suffix = ".ogg";
					} else {
						$suffix = "";
					}

					$src = get_self_url_prefix() . '/public.php?op=cached_url&hash=' . sha1($src) . $suffix;

					if ($entry->hasAttribute('poster'))
						$entry->setAttribute('poster', $src);
					else
						$entry->setAttribute('src', $src);

					$need_saving = true;
				}
			}
		}

		if ($need_saving) {
			$doc->removeChild($doc->firstChild); //remove doctype
			$res = $doc->saveHTML();
		}

		return $res;
	}

	function sanitize($str, $force_remove_images = false, $owner = false, $site_url = false, $highlight_words = false, $article_id = false) {
		if (!$owner) $owner = $_SESSION["uid"];

		$res = trim($str); if (!$res) return '';

		$charset_hack = '<head>
				<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
			</head>';

		$res = trim($res); if (!$res) return '';

		libxml_use_internal_errors(true);

		$doc = new DOMDocument();
		$doc->loadHTML($charset_hack . $res);
		$xpath = new DOMXPath($doc);

		$rewrite_base_url = $site_url ? $site_url : get_self_url_prefix();

		$entries = $xpath->query('(//a[@href]|//img[@src]|//video/source[@src]|//audio/source[@src])');

		foreach ($entries as $entry) {

			if ($entry->hasAttribute('href')) {
				$entry->setAttribute('href',
					rewrite_relative_url($rewrite_base_url, $entry->getAttribute('href')));

				$entry->setAttribute('rel', 'noopener noreferrer');
			}

			if ($entry->hasAttribute('src')) {
				$src = rewrite_relative_url($rewrite_base_url, $entry->getAttribute('src'));

				// cache stuff has gone to rewrite_cached_urls()

				$entry->setAttribute('src', $src);
			}

			if ($entry->nodeName == 'img') {
				$entry->setAttribute('referrerpolicy', 'no-referrer');

				$entry->removeAttribute('width');
				$entry->removeAttribute('height');

				if ($entry->hasAttribute('src')) {
					$is_https_url = parse_url($entry->getAttribute('src'), PHP_URL_SCHEME) === 'https';

					if (is_prefix_https() && !$is_https_url) {

						if ($entry->hasAttribute('srcset')) {
							$entry->removeAttribute('srcset');
						}

						if ($entry->hasAttribute('sizes')) {
							$entry->removeAttribute('sizes');
						}
					}
				}
			}

			if ($entry->hasAttribute('src') &&
					($owner && get_pref("STRIP_IMAGES", $owner)) || $force_remove_images || $_SESSION["bw_limit"]) {

				$p = $doc->createElement('p');

				$a = $doc->createElement('a');
				$a->setAttribute('href', $entry->getAttribute('src'));

				$a->appendChild(new DOMText($entry->getAttribute('src')));
				$a->setAttribute('target', '_blank');
				$a->setAttribute('rel', 'noopener noreferrer');

				$p->appendChild($a);

				if ($entry->nodeName == 'source') {

					if ($entry->parentNode && $entry->parentNode->parentNode)
						$entry->parentNode->parentNode->replaceChild($p, $entry->parentNode);

				} else if ($entry->nodeName == 'img') {

					if ($entry->parentNode)
						$entry->parentNode->replaceChild($p, $entry);

				}
			}

			if (strtolower($entry->nodeName) == "a") {
				$entry->setAttribute("target", "_blank");
				$entry->setAttribute("rel", "noopener noreferrer");
			}
		}

		$entries = $xpath->query('//iframe');
		foreach ($entries as $entry) {
			if (!iframe_whitelisted($entry)) {
				$entry->setAttribute('sandbox', 'allow-scripts');
			} else {
				if (is_prefix_https()) {
					$entry->setAttribute("src",
						str_replace("http://", "https://",
							$entry->getAttribute("src")));
				}
			}
		}

		$allowed_elements = array('a', 'abbr', 'address', 'acronym', 'audio', 'article', 'aside',
			'b', 'bdi', 'bdo', 'big', 'blockquote', 'body', 'br',
			'caption', 'cite', 'center', 'code', 'col', 'colgroup',
			'data', 'dd', 'del', 'details', 'description', 'dfn', 'div', 'dl', 'font',
			'dt', 'em', 'footer', 'figure', 'figcaption',
			'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'header', 'hr', 'html', 'i',
			'img', 'ins', 'kbd', 'li', 'main', 'mark', 'nav', 'noscript',
			'ol', 'p', 'pre', 'q', 'ruby', 'rp', 'rt', 's', 'samp', 'section',
			'small', 'source', 'span', 'strike', 'strong', 'sub', 'summary',
			'sup', 'table', 'tbody', 'td', 'tfoot', 'th', 'thead', 'time',
			'tr', 'track', 'tt', 'u', 'ul', 'var', 'wbr', 'video', 'xml:namespace' );

		if ($_SESSION['hasSandbox']) $allowed_elements[] = 'iframe';

		$disallowed_attributes = array('id', 'style', 'class');

		foreach (PluginHost::getInstance()->get_hooks(PluginHost::HOOK_SANITIZE) as $plugin) {
			$retval = $plugin->hook_sanitize($doc, $site_url, $allowed_elements, $disallowed_attributes, $article_id);
			if (is_array($retval)) {
				$doc = $retval[0];
				$allowed_elements = $retval[1];
				$disallowed_attributes = $retval[2];
			} else {
				$doc = $retval;
			}
		}

		$doc->removeChild($doc->firstChild); //remove doctype
		$doc = strip_harmful_tags($doc, $allowed_elements, $disallowed_attributes);

		if ($highlight_words) {
			foreach ($highlight_words as $word) {

				// http://stackoverflow.com/questions/4081372/highlight-keywords-in-a-paragraph

				$elements = $xpath->query("//*/text()");

				foreach ($elements as $child) {

					$fragment = $doc->createDocumentFragment();
					$text = $child->textContent;

					while (($pos = mb_stripos($text, $word)) !== false) {
						$fragment->appendChild(new DomText(mb_substr($text, 0, $pos)));
						$word = mb_substr($text, $pos, mb_strlen($word));
						$highlight = $doc->createElement('span');
						$highlight->appendChild(new DomText($word));
						$highlight->setAttribute('class', 'highlight');
						$fragment->appendChild($highlight);
						$text = mb_substr($text, $pos + mb_strlen($word));
					}

					if (!empty($text)) $fragment->appendChild(new DomText($text));

					$child->parentNode->replaceChild($fragment, $child);
				}
			}
		}

		$res = $doc->saveHTML();

		/* strip everything outside of <body>...</body> */

		$res_frag = array();
		if (preg_match('/<body>(.*)<\/body>/is', $res, $res_frag)) {
			return $res_frag[1];
		} else {
			return $res;
		}
	}

	function strip_harmful_tags($doc, $allowed_elements, $disallowed_attributes) {
		$xpath = new DOMXPath($doc);
		$entries = $xpath->query('//*');

		foreach ($entries as $entry) {
			if (!in_array($entry->nodeName, $allowed_elements)) {
				$entry->parentNode->removeChild($entry);
			}

			if ($entry->hasAttributes()) {
				$attrs_to_remove = array();

				foreach ($entry->attributes as $attr) {

					if (strpos($attr->nodeName, 'on') === 0) {
						array_push($attrs_to_remove, $attr);
					}

					if ($attr->nodeName == 'href' && stripos($attr->value, 'javascript:') === 0) {
						array_push($attrs_to_remove, $attr);
					}

					if (in_array($attr->nodeName, $disallowed_attributes)) {
						array_push($attrs_to_remove, $attr);
					}
				}

				foreach ($attrs_to_remove as $attr) {
					$entry->removeAttributeNode($attr);
				}
			}
		}

		return $doc;
	}

	function trim_array($array) {
		$tmp = $array;
		array_walk($tmp, 'trim');
		return $tmp;
	}

	function tag_is_valid($tag) {
		if (!$tag || is_numeric($tag) || mb_strlen($tag) > 250)
			return false;

		return true;
	}

	function render_login_form() {
		header('Cache-Control: public');

		require_once "login_form.php";
		exit;
	}

	function T_sprintf() {
		$args = func_get_args();
		return vsprintf(__(array_shift($args)), $args);
	}

	function print_checkpoint($n, $s) {
		$ts = microtime(true);
		echo sprintf("<!-- CP[$n] %.4f seconds -->\n", $ts - $s);
		return $ts;
	}

	function sanitize_tag($tag) {
		$tag = trim($tag);

		$tag = mb_strtolower($tag, 'utf-8');

		$tag = preg_replace('/[,\'\"\+\>\<]/', "", $tag);

		if (DB_TYPE == "mysql") {
			$tag = preg_replace('/[\x{10000}-\x{10FFFF}]/u', "\xEF\xBF\xBD", $tag);
		}

		return $tag;
	}

	function is_server_https() {
		return (!empty($_SERVER['HTTPS']) && ($_SERVER['HTTPS'] != 'off')) || $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https';
	}

	function is_prefix_https() {
		return parse_url(SELF_URL_PATH, PHP_URL_SCHEME) == 'https';
	}

	// this returns SELF_URL_PATH sans ending slash
	function get_self_url_prefix() {
		if (strrpos(SELF_URL_PATH, "/") === strlen(SELF_URL_PATH)-1) {
			return substr(SELF_URL_PATH, 0, strlen(SELF_URL_PATH)-1);
		} else {
			return SELF_URL_PATH;
		}
	}

	function encrypt_password($pass, $salt = '', $mode2 = false) {
		if ($salt && $mode2) {
			return "MODE2:" . hash('sha256', $salt . $pass);
		} else if ($salt) {
			return "SHA1X:" . sha1("$salt:$pass");
		} else {
			return "SHA1:" . sha1($pass);
		}
	} // function encrypt_password

	function load_filters($feed_id, $owner_uid) {
		$filters = array();

		$feed_id = (int) $feed_id;
		$cat_id = (int)Feeds::getFeedCategory($feed_id);

		if ($cat_id == 0)
			$null_cat_qpart = "cat_id IS NULL OR";
		else
			$null_cat_qpart = "";

		$pdo = Db::pdo();

		$sth = $pdo->prepare("SELECT * FROM ttrss_filters2 WHERE
				owner_uid = ? AND enabled = true ORDER BY order_id, title");
		$sth->execute([$owner_uid]);

		$check_cats = array_merge(
			Feeds::getParentCategories($cat_id, $owner_uid),
			[$cat_id]);

		$check_cats_str = join(",", $check_cats);
		$check_cats_fullids = array_map(function($a) { return "CAT:$a"; }, $check_cats);

		while ($line = $sth->fetch()) {
			$filter_id = $line["id"];

			$match_any_rule = sql_bool_to_bool($line["match_any_rule"]);

			$sth2 = $pdo->prepare("SELECT
					r.reg_exp, r.inverse, r.feed_id, r.cat_id, r.cat_filter, r.match_on, t.name AS type_name
					FROM ttrss_filters2_rules AS r,
					ttrss_filter_types AS t
					WHERE
						(match_on IS NOT NULL OR
						  (($null_cat_qpart (cat_id IS NULL AND cat_filter = false) OR cat_id IN ($check_cats_str)) AND
						  (feed_id IS NULL OR feed_id = ?))) AND
						filter_type = t.id AND filter_id = ?");
			$sth2->execute([$feed_id, $filter_id]);

			$rules = array();
			$actions = array();

			while ($rule_line = $sth2->fetch()) {
	#				print_r($rule_line);

				if ($rule_line["match_on"]) {
					$match_on = json_decode($rule_line["match_on"], true);

					if (in_array("0", $match_on) || in_array($feed_id, $match_on) || count(array_intersect($check_cats_fullids, $match_on)) > 0) {

						$rule = array();
						$rule["reg_exp"] = $rule_line["reg_exp"];
						$rule["type"] = $rule_line["type_name"];
						$rule["inverse"] = sql_bool_to_bool($rule_line["inverse"]);

						array_push($rules, $rule);
					} else if (!$match_any_rule) {
						// this filter contains a rule that doesn't match to this feed/category combination
						// thus filter has to be rejected

						$rules = [];
						break;
					}

				} else {

					$rule = array();
					$rule["reg_exp"] = $rule_line["reg_exp"];
					$rule["type"] = $rule_line["type_name"];
					$rule["inverse"] = sql_bool_to_bool($rule_line["inverse"]);

					array_push($rules, $rule);
				}
			}

			if (count($rules) > 0) {
				$sth2 = $pdo->prepare("SELECT a.action_param,t.name AS type_name
						FROM ttrss_filters2_actions AS a,
						ttrss_filter_actions AS t
						WHERE
							action_id = t.id AND filter_id = ?");
				$sth2->execute([$filter_id]);

				while ($action_line = $sth2->fetch()) {
					#				print_r($action_line);

					$action = array();
					$action["type"] = $action_line["type_name"];
					$action["param"] = $action_line["action_param"];

					array_push($actions, $action);
				}
			}

			$filter = array();
			$filter["match_any_rule"] = sql_bool_to_bool($line["match_any_rule"]);
			$filter["inverse"] = sql_bool_to_bool($line["inverse"]);
			$filter["rules"] = $rules;
			$filter["actions"] = $actions;

			if (count($rules) > 0 && count($actions) > 0) {
				array_push($filters, $filter);
			}
		}

		return $filters;
	}

	function get_score_pic($score) {
		if ($score > 100) {
			return "score_high.png";
		} else if ($score > 0) {
			return "score_half_high.png";
		} else if ($score < -100) {
			return "score_low.png";
		} else if ($score < 0) {
			return "score_half_low.png";
		} else {
			return "score_neutral.png";
		}
	}

	function init_plugins() {
		PluginHost::getInstance()->load(PLUGINS, PluginHost::KIND_ALL);

		return true;
	}

	function add_feed_category($feed_cat, $parent_cat_id = false) {

		if (!$feed_cat) return false;

		$feed_cat = mb_substr($feed_cat, 0, 250);
		if (!$parent_cat_id) $parent_cat_id = null;

		$pdo = Db::pdo();
		$tr_in_progress = false;

		try {
			$pdo->beginTransaction();
		} catch (Exception $e) {
			$tr_in_progress = true;
		}

		$sth = $pdo->prepare("SELECT id FROM ttrss_feed_categories
				WHERE (parent_cat = :parent OR (:parent IS NULL AND parent_cat IS NULL))
				AND title = :title AND owner_uid = :uid");
		$sth->execute([':parent' => $parent_cat_id, ':title' => $feed_cat, ':uid' => $_SESSION['uid']]);

		if (!$sth->fetch()) {

			$sth = $pdo->prepare("INSERT INTO ttrss_feed_categories (owner_uid,title,parent_cat)
					VALUES (?, ?, ?)");
			$sth->execute([$_SESSION['uid'], $feed_cat, $parent_cat_id]);

			if (!$tr_in_progress) $pdo->commit();

			return true;
		}

		$pdo->commit();

		return false;
	}

	/**
	 * Fixes incomplete URLs by prepending "http://".
	 * Also replaces feed:// with http://, and
	 * prepends a trailing slash if the url is a domain name only.
	 *
	 * @param string $url Possibly incomplete URL
	 *
	 * @return string Fixed URL.
	 */
	function fix_url($url) {

		// support schema-less urls
		if (strpos($url, '//') === 0) {
			$url = 'https:' . $url;
		}

		if (strpos($url, '://') === false) {
			$url = 'http://' . $url;
		} else if (substr($url, 0, 5) == 'feed:') {
			$url = 'http:' . substr($url, 5);
		}

		//prepend slash if the URL has no slash in it
		// "http://www.example" -> "http://www.example/"
		if (strpos($url, '/', strpos($url, ':') + 3) === false) {
			$url .= '/';
		}

		//convert IDNA hostname to punycode if possible
		if (function_exists("idn_to_ascii")) {
			$parts = parse_url($url);
			if (mb_detect_encoding($parts['host']) != 'ASCII')
			{
				$parts['host'] = idn_to_ascii($parts['host']);
				$url = build_url($parts);
			}
		}

		if ($url != "http:///")
			return $url;
		else
			return '';
	}

	function validate_feed_url($url) {
		$parts = parse_url($url);

		return ($parts['scheme'] == 'http' || $parts['scheme'] == 'feed' || $parts['scheme'] == 'https');

	}

	/* function save_email_address($email) {
		// FIXME: implement persistent storage of emails

		if (!$_SESSION['stored_emails'])
			$_SESSION['stored_emails'] = array();

		if (!in_array($email, $_SESSION['stored_emails']))
			array_push($_SESSION['stored_emails'], $email);
	} */


	function get_feed_access_key($feed_id, $is_cat, $owner_uid = false) {

		if (!$owner_uid) $owner_uid = $_SESSION["uid"];

		$is_cat = bool_to_sql_bool($is_cat);

		$pdo = Db::pdo();

		$sth = $pdo->prepare("SELECT access_key FROM ttrss_access_keys
				WHERE feed_id = ? AND is_cat = ?
				AND owner_uid = ?");
		$sth->execute([$feed_id, (int)$is_cat, $owner_uid]);

		if ($row = $sth->fetch()) {
			return $row["access_key"];
		} else {
			$key = uniqid_short();

			$sth = $pdo->prepare("INSERT INTO ttrss_access_keys
					(access_key, feed_id, is_cat, owner_uid)
					VALUES (?, ?, ?, ?)");

			$sth->execute([$key, $feed_id, (int)$is_cat, $owner_uid]);

			return $key;
		}
	}

	function get_feeds_from_html($url, $content)
	{
		$url     = fix_url($url);
		$baseUrl = substr($url, 0, strrpos($url, '/') + 1);

		libxml_use_internal_errors(true);

		$doc = new DOMDocument();
		$doc->loadHTML($content);
		$xpath = new DOMXPath($doc);
		$entries = $xpath->query('/html/head/link[@rel="alternate" and '.
			'(contains(@type,"rss") or contains(@type,"atom"))]|/html/head/link[@rel="feed"]');
		$feedUrls = array();
		foreach ($entries as $entry) {
			if ($entry->hasAttribute('href')) {
				$title = $entry->getAttribute('title');
				if ($title == '') {
					$title = $entry->getAttribute('type');
				}
				$feedUrl = rewrite_relative_url(
					$baseUrl, $entry->getAttribute('href')
				);
				$feedUrls[$feedUrl] = $title;
			}
		}
		return $feedUrls;
	}

	function is_html($content) {
		return preg_match("/<html|DOCTYPE html/i", substr($content, 0, 100)) !== 0;
	}

	function url_is_html($url, $login = false, $pass = false) {
		return is_html(fetch_file_contents($url, false, $login, $pass));
	}

	function build_url($parts) {
		return $parts['scheme'] . "://" . $parts['host'] . $parts['path'];
	}

	function cleanup_url_path($path) {
		$path = str_replace("/./", "/", $path);
		$path = str_replace("//", "/", $path);

		return $path;
	}

	/**
	 * Converts a (possibly) relative URL to a absolute one.
	 *
	 * @param string $url     Base URL (i.e. from where the document is)
	 * @param string $rel_url Possibly relative URL in the document
	 *
	 * @return string Absolute URL
	 */
	function rewrite_relative_url($url, $rel_url) {
		if (strpos($rel_url, "://") !== false) {
			return $rel_url;
		} else if (strpos($rel_url, "//") === 0) {
			# protocol-relative URL (rare but they exist)
			return $rel_url;
		} else if (preg_match("/^[a-z]+:/i", $rel_url)) {
			# magnet:, feed:, etc
			return $rel_url;
		} else if (strpos($rel_url, "/") === 0) {
			$parts = parse_url($url);
			$parts['path'] = $rel_url;
			$parts['path'] = cleanup_url_path($parts['path']);

			return build_url($parts);

		} else {
			$parts = parse_url($url);
			if (!isset($parts['path'])) {
				$parts['path'] = '/';
			}
			$dir = $parts['path'];
			if (substr($dir, -1) !== '/') {
				$dir = dirname($parts['path']);
				$dir !== '/' && $dir .= '/';
			}
			$parts['path'] = $dir . $rel_url;
			$parts['path'] = cleanup_url_path($parts['path']);

			return build_url($parts);
		}
	}

	function cleanup_tags($days = 14, $limit = 1000) {

		$days = (int) $days;

		if (DB_TYPE == "pgsql") {
			$interval_query = "date_updated < NOW() - INTERVAL '$days days'";
		} else if (DB_TYPE == "mysql") {
			$interval_query = "date_updated < DATE_SUB(NOW(), INTERVAL $days DAY)";
		}

		$tags_deleted = 0;

		$pdo = Db::pdo();

		while ($limit > 0) {
			$limit_part = 500;

			$sth = $pdo->prepare("SELECT ttrss_tags.id AS id
					FROM ttrss_tags, ttrss_user_entries, ttrss_entries
					WHERE post_int_id = int_id AND $interval_query AND
					ref_id = ttrss_entries.id AND tag_cache != '' LIMIT ?");
			$sth->execute([$limit]);

			$ids = array();

			while ($line = $sth->fetch()) {
				array_push($ids, $line['id']);
			}

			if (count($ids) > 0) {
				$ids = join(",", $ids);

				$usth = $pdo->query("DELETE FROM ttrss_tags WHERE id IN ($ids)");
				$tags_deleted = $usth->rowCount();
			} else {
				break;
			}

			$limit -= $limit_part;
		}

		return $tags_deleted;
	}

	function print_user_stylesheet() {
		$value = get_pref('USER_STYLESHEET');

		if ($value) {
			print "<style type=\"text/css\">";
			print str_replace("<br/>", "\n", $value);
			print "</style>";
		}

	}

	function filter_to_sql($filter, $owner_uid) {
		$query = array();

		$pdo = Db::pdo();

		if (DB_TYPE == "pgsql")
			$reg_qpart = "~";
		else
			$reg_qpart = "REGEXP";

		foreach ($filter["rules"] AS $rule) {
			$rule['reg_exp'] = str_replace('/', '\/', $rule["reg_exp"]);
			$regexp_valid = preg_match('/' . $rule['reg_exp'] . '/',
					$rule['reg_exp']) !== FALSE;

			if ($regexp_valid) {

				$rule['reg_exp'] = $pdo->quote($rule['reg_exp']);

				switch ($rule["type"]) {
					case "title":
						$qpart = "LOWER(ttrss_entries.title) $reg_qpart LOWER('".
							$rule['reg_exp'] . "')";
						break;
					case "content":
						$qpart = "LOWER(ttrss_entries.content) $reg_qpart LOWER('".
							$rule['reg_exp'] . "')";
						break;
					case "both":
						$qpart = "LOWER(ttrss_entries.title) $reg_qpart LOWER('".
							$rule['reg_exp'] . "') OR LOWER(" .
							"ttrss_entries.content) $reg_qpart LOWER('" . $rule['reg_exp'] . "')";
						break;
					case "tag":
						$qpart = "LOWER(ttrss_user_entries.tag_cache) $reg_qpart LOWER('".
							$rule['reg_exp'] . "')";
						break;
					case "link":
						$qpart = "LOWER(ttrss_entries.link) $reg_qpart LOWER('".
							$rule['reg_exp'] . "')";
						break;
					case "author":
						$qpart = "LOWER(ttrss_entries.author) $reg_qpart LOWER('".
							$rule['reg_exp'] . "')";
						break;
				}

				if (isset($rule['inverse'])) $qpart = "NOT ($qpart)";

				if (isset($rule["feed_id"]) && $rule["feed_id"] > 0) {
					$qpart .= " AND feed_id = " . $pdo->quote($rule["feed_id"]);
				}

				if (isset($rule["cat_id"])) {

					if ($rule["cat_id"] > 0) {
						$children = Feeds::getChildCategories($rule["cat_id"], $owner_uid);
						array_push($children, $rule["cat_id"]);
						$children = array_map("intval", $children);

						$children = join(",", $children);

						$cat_qpart = "cat_id IN ($children)";
					} else {
						$cat_qpart = "cat_id IS NULL";
					}

					$qpart .= " AND $cat_qpart";
				}

				$qpart .= " AND feed_id IS NOT NULL";

				array_push($query, "($qpart)");

			}
		}

		if (count($query) > 0) {
			$fullquery = "(" . join($filter["match_any_rule"] ? "OR" : "AND", $query) . ")";
		} else {
			$fullquery = "(false)";
		}

		if ($filter['inverse']) $fullquery = "(NOT $fullquery)";

		return $fullquery;
	}

	if (!function_exists('gzdecode')) {
		function gzdecode($string) { // no support for 2nd argument
			return file_get_contents('compress.zlib://data:who/cares;base64,'.
				base64_encode($string));
		}
	}

	function get_random_bytes($length) {
		if (function_exists('openssl_random_pseudo_bytes')) {
			return openssl_random_pseudo_bytes($length);
		} else {
			$output = "";

			for ($i = 0; $i < $length; $i++)
				$output .= chr(mt_rand(0, 255));

			return $output;
		}
	}

	function read_stdin() {
		$fp = fopen("php://stdin", "r");

		if ($fp) {
			$line = trim(fgets($fp));
			fclose($fp);
			return $line;
		}

		return null;
	}

	function implements_interface($class, $interface) {
		return in_array($interface, class_implements($class));
	}

	function get_minified_js($files) {

		$rv = '';

		foreach ($files as $js) {
			if (!isset($_GET['debug'])) {
				$cached_file = CACHE_DIR . "/js/".basename($js);

				if (file_exists($cached_file) && is_readable($cached_file) && filemtime($cached_file) >= filemtime("js/$js")) {

					list($header, $contents) = explode("\n", file_get_contents($cached_file), 2);

					if ($header && $contents) {
						list($htag, $hversion) = explode(":", $header);

						if ($htag == "tt-rss" && $hversion == VERSION) {
							$rv .= $contents;
							continue;
						}
					}
				}

				$minified = JShrink\Minifier::minify(file_get_contents("js/$js"));
				file_put_contents($cached_file, "tt-rss:" . VERSION . "\n" . $minified);
				$rv .= $minified;

			} else {
				$rv .= file_get_contents("js/$js"); // no cache in debug mode
			}
		}

		return $rv;
	}

	function calculate_dep_timestamp() {
		$files = array_merge(glob("js/*.js"), glob("css/*.css"));

		$max_ts = -1;

		foreach ($files as $file) {
			if (filemtime($file) > $max_ts) $max_ts = filemtime($file);
		}

		return $max_ts;
	}

	function T_js_decl($s1, $s2) {
		if ($s1 && $s2) {
			$s1 = preg_replace("/\n/", "", $s1);
			$s2 = preg_replace("/\n/", "", $s2);

			$s1 = preg_replace("/\"/", "\\\"", $s1);
			$s2 = preg_replace("/\"/", "\\\"", $s2);

			return "T_messages[\"$s1\"] = \"$s2\";\n";
		}
	}

	function init_js_translations() {

		print 'var T_messages = new Object();

			function __(msg) {
				if (T_messages[msg]) {
					return T_messages[msg];
				} else {
					return msg;
				}
			}

			function ngettext(msg1, msg2, n) {
				return __((parseInt(n) > 1) ? msg2 : msg1);
			}';

		$l10n = _get_reader();

		for ($i = 0; $i < $l10n->total; $i++) {
			$orig = $l10n->get_original_string($i);
			if(strpos($orig, "\000") !== FALSE) { // Plural forms
				$key = explode(chr(0), $orig);
				print T_js_decl($key[0], _ngettext($key[0], $key[1], 1)); // Singular
				print T_js_decl($key[1], _ngettext($key[0], $key[1], 2)); // Plural
			} else {
				$translation = __($orig);
				print T_js_decl($orig, $translation);
			}
		}
	}

	function get_theme_path($theme) {
		if ($theme == "default.php")
			return "css/default.css";

		$check = "themes/$theme";
		if (file_exists($check)) return $check;

		$check = "themes.local/$theme";
		if (file_exists($check)) return $check;
	}

	function theme_valid($theme) {
		$bundled_themes = [ "default.php", "night.css", "compact.css" ];

		if (in_array($theme, $bundled_themes)) return true;

		$file = "themes/" . basename($theme);

		if (!file_exists($file)) $file = "themes.local/" . basename($theme);

		if (file_exists($file) && is_readable($file)) {
			$fh = fopen($file, "r");

			if ($fh) {
				$header = fgets($fh);
				fclose($fh);

				return strpos($header, "supports-version:" . VERSION_STATIC) !== FALSE;
			}
		}

		return false;
	}

	/**
	 * @SuppressWarnings(unused)
	 */
	function error_json($code) {
		require_once "errors.php";

		@$message = $ERRORS[$code];

		return json_encode(array("error" =>
			array("code" => $code, "message" => $message)));

	}

	/*function abs_to_rel_path($dir) {
		$tmp = str_replace(dirname(__DIR__), "", $dir);

		if (strlen($tmp) > 0 && substr($tmp, 0, 1) == "/") $tmp = substr($tmp, 1);

		return $tmp;
	}*/

	function get_upload_error_message($code) {

		$errors = array(
			0 => __('There is no error, the file uploaded with success'),
			1 => __('The uploaded file exceeds the upload_max_filesize directive in php.ini'),
			2 => __('The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form'),
			3 => __('The uploaded file was only partially uploaded'),
			4 => __('No file was uploaded'),
			6 => __('Missing a temporary folder'),
			7 => __('Failed to write file to disk.'),
			8 => __('A PHP extension stopped the file upload.'),
		);

		return $errors[$code];
	}

	function base64_img($filename) {
		if (file_exists($filename)) {
			$ext = pathinfo($filename, PATHINFO_EXTENSION);

			return "data:image/$ext;base64," . base64_encode(file_get_contents($filename));
		} else {
			return "";
		}
	}

	/*	this is essentially a wrapper for readfile() which allows plugins to hook
		output with httpd-specific "fast" implementation i.e. X-Sendfile or whatever else

		hook function should return true if request was handled (or at least attempted to)

		note that this can be called without user context so the plugin to handle this
		should be loaded systemwide in config.php */
	function send_local_file($filename) {
		if (file_exists($filename)) {

			if (is_writable($filename)) touch($filename);

			$tmppluginhost = new PluginHost();

			$tmppluginhost->load(PLUGINS, PluginHost::KIND_SYSTEM);
			$tmppluginhost->load_data();

			foreach ($tmppluginhost->get_hooks(PluginHost::HOOK_SEND_LOCAL_FILE) as $plugin) {
				if ($plugin->hook_send_local_file($filename)) return true;
			}

			$mimetype = mime_content_type($filename);

			// this is hardly ideal but 1) only media is cached in images/ and 2) seemingly only mp4
			// video files are detected as octet-stream by mime_content_type()

			if ($mimetype == "application/octet-stream")
				$mimetype = "video/mp4";

			header("Content-type: $mimetype");

			$stamp = gmdate("D, d M Y H:i:s", filemtime($filename)) . " GMT";
			header("Last-Modified: $stamp", true);

			return readfile($filename);
		} else {
			return false;
		}
	}

	function check_mysql_tables() {
		$pdo = Db::pdo();

		$sth = $pdo->prepare("SELECT engine, table_name FROM information_schema.tables WHERE
			table_schema = ? AND table_name LIKE 'ttrss_%' AND engine != 'InnoDB'");
		$sth->execute([DB_NAME]);

		$bad_tables = [];

		while ($line = $sth->fetch()) {
			array_push($bad_tables, $line);
		}

		return $bad_tables;
	}

	function validate_field($string, $allowed, $default = "") {
		if (in_array($string, $allowed))
			return $string;
		else
			return $default;
	}

	function arr_qmarks($arr) {
		return str_repeat('?,', count($arr) - 1) . '?';
	}