xref: /dokuwiki/inc/common.php (revision 84c1127cc070777c8cbcf488f5422bc4b71470a8)

<?php
/**
 * Common DokuWiki functions
 *
 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
 * @author     Andreas Gohr <andi@splitbrain.org>
 */

if(!defined('DOKU_INC')) die('meh.');

/**
 * These constants are used with the recents function
 */
define('RECENTS_SKIP_DELETED', 2);
define('RECENTS_SKIP_MINORS', 4);
define('RECENTS_SKIP_SUBSPACES', 8);
define('RECENTS_MEDIA_CHANGES', 16);
define('RECENTS_MEDIA_PAGES_MIXED', 32);

/**
 * Wrapper around htmlspecialchars()
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 * @see    htmlspecialchars()
 */
function hsc($string) {
    return htmlspecialchars($string, ENT_QUOTES, 'UTF-8');
}

/**
 * print a newline terminated string
 *
 * You can give an indention as optional parameter
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function ptln($string, $indent = 0) {
    echo str_repeat(' ', $indent)."$string\n";
}

/**
 * strips control characters (<32) from the given string
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function stripctl($string) {
    return preg_replace('/[\x00-\x1F]+/s', '', $string);
}

/**
 * Return a secret token to be used for CSRF attack prevention
 *
 * @author  Andreas Gohr <andi@splitbrain.org>
 * @link    http://en.wikipedia.org/wiki/Cross-site_request_forgery
 * @link    http://christ1an.blogspot.com/2007/04/preventing-csrf-efficiently.html
 * @return  string
 */
function getSecurityToken() {
    return md5(auth_cookiesalt().session_id().$_SERVER['REMOTE_USER']);
}

/**
 * Check the secret CSRF token
 */
function checkSecurityToken($token = null) {
    global $INPUT;
    if(!$_SERVER['REMOTE_USER']) return true; // no logged in user, no need for a check

    if(is_null($token)) $token = $INPUT->str('sectok');
    if(getSecurityToken() != $token) {
        msg('Security Token did not match. Possible CSRF attack.', -1);
        return false;
    }
    return true;
}

/**
 * Print a hidden form field with a secret CSRF token
 *
 * @author  Andreas Gohr <andi@splitbrain.org>
 */
function formSecurityToken($print = true) {
    $ret = '<div class="no"><input type="hidden" name="sectok" value="'.getSecurityToken().'" /></div>'."\n";
    if($print) echo $ret;
    return $ret;
}

/**
 * Return info about the current document as associative
 * array.
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function pageinfo() {
    global $ID;
    global $REV;
    global $RANGE;
    global $USERINFO;
    global $lang;

    // include ID & REV not redundant, as some parts of DokuWiki may temporarily change $ID, e.g. p_wiki_xhtml
    // FIXME ... perhaps it would be better to ensure the temporary changes weren't necessary
    $info['id']  = $ID;
    $info['rev'] = $REV;

    // set info about manager/admin status.
    $info['isadmin']   = false;
    $info['ismanager'] = false;
    if(isset($_SERVER['REMOTE_USER'])) {
        $sub = new Subscription();

        $info['userinfo']   = $USERINFO;
        $info['perm']       = auth_quickaclcheck($ID);
        $info['subscribed'] = $sub->user_subscription();
        $info['client']     = $_SERVER['REMOTE_USER'];

        if($info['perm'] == AUTH_ADMIN) {
            $info['isadmin']   = true;
            $info['ismanager'] = true;
        } elseif(auth_ismanager()) {
            $info['ismanager'] = true;
        }

        // if some outside auth were used only REMOTE_USER is set
        if(!$info['userinfo']['name']) {
            $info['userinfo']['name'] = $_SERVER['REMOTE_USER'];
        }

    } else {
        $info['perm']       = auth_aclcheck($ID, '', null);
        $info['subscribed'] = false;
        $info['client']     = clientIP(true);
    }

    $info['namespace'] = getNS($ID);
    $info['locked']    = checklock($ID);
    $info['filepath']  = fullpath(wikiFN($ID));
    $info['exists']    = @file_exists($info['filepath']);
    if($REV) {
        //check if current revision was meant
        if($info['exists'] && (@filemtime($info['filepath']) == $REV)) {
            $REV = '';
        } elseif($RANGE) {
            //section editing does not work with old revisions!
            $REV   = '';
            $RANGE = '';
            msg($lang['nosecedit'], 0);
        } else {
            //really use old revision
            $info['filepath'] = fullpath(wikiFN($ID, $REV));
            $info['exists']   = @file_exists($info['filepath']);
        }
    }
    $info['rev'] = $REV;
    if($info['exists']) {
        $info['writable'] = (is_writable($info['filepath']) &&
            ($info['perm'] >= AUTH_EDIT));
    } else {
        $info['writable'] = ($info['perm'] >= AUTH_CREATE);
    }
    $info['editable'] = ($info['writable'] && empty($info['locked']));
    $info['lastmod']  = @filemtime($info['filepath']);

    //load page meta data
    $info['meta'] = p_get_metadata($ID);

    //who's the editor
    if($REV) {
        $revinfo = getRevisionInfo($ID, $REV, 1024);
    } else {
        if(is_array($info['meta']['last_change'])) {
            $revinfo = $info['meta']['last_change'];
        } else {
            $revinfo = getRevisionInfo($ID, $info['lastmod'], 1024);
            // cache most recent changelog line in metadata if missing and still valid
            if($revinfo !== false) {
                $info['meta']['last_change'] = $revinfo;
                p_set_metadata($ID, array('last_change' => $revinfo));
            }
        }
    }
    //and check for an external edit
    if($revinfo !== false && $revinfo['date'] != $info['lastmod']) {
        // cached changelog line no longer valid
        $revinfo                     = false;
        $info['meta']['last_change'] = $revinfo;
        p_set_metadata($ID, array('last_change' => $revinfo));
    }

    $info['ip']   = $revinfo['ip'];
    $info['user'] = $revinfo['user'];
    $info['sum']  = $revinfo['sum'];
    // See also $INFO['meta']['last_change'] which is the most recent log line for page $ID.
    // Use $INFO['meta']['last_change']['type']===DOKU_CHANGE_TYPE_MINOR_EDIT in place of $info['minor'].

    if($revinfo['user']) {
        $info['editor'] = $revinfo['user'];
    } else {
        $info['editor'] = $revinfo['ip'];
    }

    // draft
    $draft = getCacheName($info['client'].$ID, '.draft');
    if(@file_exists($draft)) {
        if(@filemtime($draft) < @filemtime(wikiFN($ID))) {
            // remove stale draft
            @unlink($draft);
        } else {
            $info['draft'] = $draft;
        }
    }

    // mobile detection
    $info['ismobile'] = clientismobile();

    return $info;
}

/**
 * Build an string of URL parameters
 *
 * @author Andreas Gohr
 */
function buildURLparams($params, $sep = '&amp;') {
    $url = '';
    $amp = false;
    foreach($params as $key => $val) {
        if($amp) $url .= $sep;

        $url .= rawurlencode($key).'=';
        $url .= rawurlencode((string) $val);
        $amp = true;
    }
    return $url;
}

/**
 * Build an string of html tag attributes
 *
 * Skips keys starting with '_', values get HTML encoded
 *
 * @author Andreas Gohr
 */
function buildAttributes($params, $skipempty = false) {
    $url   = '';
    $white = false;
    foreach($params as $key => $val) {
        if($key{0} == '_') continue;
        if($val === '' && $skipempty) continue;
        if($white) $url .= ' ';

        $url .= $key.'="';
        $url .= htmlspecialchars($val);
        $url .= '"';
        $white = true;
    }
    return $url;
}

/**
 * This builds the breadcrumb trail and returns it as array
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function breadcrumbs() {
    // we prepare the breadcrumbs early for quick session closing
    static $crumbs = null;
    if($crumbs != null) return $crumbs;

    global $ID;
    global $ACT;
    global $conf;

    //first visit?
    $crumbs = isset($_SESSION[DOKU_COOKIE]['bc']) ? $_SESSION[DOKU_COOKIE]['bc'] : array();
    //we only save on show and existing wiki documents
    $file = wikiFN($ID);
    if($ACT != 'show' || !@file_exists($file)) {
        $_SESSION[DOKU_COOKIE]['bc'] = $crumbs;
        return $crumbs;
    }

    // page names
    $name = noNSorNS($ID);
    if(useHeading('navigation')) {
        // get page title
        $title = p_get_first_heading($ID, METADATA_RENDER_USING_SIMPLE_CACHE);
        if($title) {
            $name = $title;
        }
    }

    //remove ID from array
    if(isset($crumbs[$ID])) {
        unset($crumbs[$ID]);
    }

    //add to array
    $crumbs[$ID] = $name;
    //reduce size
    while(count($crumbs) > $conf['breadcrumbs']) {
        array_shift($crumbs);
    }
    //save to session
    $_SESSION[DOKU_COOKIE]['bc'] = $crumbs;
    return $crumbs;
}

/**
 * Filter for page IDs
 *
 * This is run on a ID before it is outputted somewhere
 * currently used to replace the colon with something else
 * on Windows systems and to have proper URL encoding
 *
 * Urlencoding is ommitted when the second parameter is false
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function idfilter($id, $ue = true) {
    global $conf;
    if($conf['useslash'] && $conf['userewrite']) {
        $id = strtr($id, ':', '/');
    } elseif(strtoupper(substr(PHP_OS, 0, 3)) === 'WIN' &&
        $conf['userewrite']
    ) {
        $id = strtr($id, ':', ';');
    }
    if($ue) {
        $id = rawurlencode($id);
        $id = str_replace('%3A', ':', $id); //keep as colon
        $id = str_replace('%2F', '/', $id); //keep as slash
    }
    return $id;
}

/**
 * This builds a link to a wikipage
 *
 * It handles URL rewriting and adds additional parameter if
 * given in $more
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function wl($id = '', $urlParameters = '', $absolute = false, $separator = '&amp;') {
    global $conf;
    if(is_array($urlParameters)) {
        $urlParameters = buildURLparams($urlParameters, $separator);
    } else {
        $urlParameters = str_replace(',', $separator, $urlParameters);
    }
    if($id === '') {
        $id = $conf['start'];
    }
    $id = idfilter($id);
    if($absolute) {
        $xlink = DOKU_URL;
    } else {
        $xlink = DOKU_BASE;
    }

    if($conf['userewrite'] == 2) {
        $xlink .= DOKU_SCRIPT.'/'.$id;
        if($urlParameters) $xlink .= '?'.$urlParameters;
    } elseif($conf['userewrite']) {
        $xlink .= $id;
        if($urlParameters) $xlink .= '?'.$urlParameters;
    } elseif($id) {
        $xlink .= DOKU_SCRIPT.'?id='.$id;
        if($urlParameters) $xlink .= $separator.$urlParameters;
    } else {
        $xlink .= DOKU_SCRIPT;
        if($urlParameters) $xlink .= '?'.$urlParameters;
    }

    return $xlink;
}

/**
 * This builds a link to an alternate page format
 *
 * Handles URL rewriting if enabled. Follows the style of wl().
 *
 * @author Ben Coburn <btcoburn@silicodon.net>
 */
function exportlink($id = '', $format = 'raw', $more = '', $abs = false, $sep = '&amp;') {
    global $conf;
    if(is_array($more)) {
        $more = buildURLparams($more, $sep);
    } else {
        $more = str_replace(',', $sep, $more);
    }

    $format = rawurlencode($format);
    $id     = idfilter($id);
    if($abs) {
        $xlink = DOKU_URL;
    } else {
        $xlink = DOKU_BASE;
    }

    if($conf['userewrite'] == 2) {
        $xlink .= DOKU_SCRIPT.'/'.$id.'?do=export_'.$format;
        if($more) $xlink .= $sep.$more;
    } elseif($conf['userewrite'] == 1) {
        $xlink .= '_export/'.$format.'/'.$id;
        if($more) $xlink .= '?'.$more;
    } else {
        $xlink .= DOKU_SCRIPT.'?do=export_'.$format.$sep.'id='.$id;
        if($more) $xlink .= $sep.$more;
    }

    return $xlink;
}

/**
 * Build a link to a media file
 *
 * Will return a link to the detail page if $direct is false
 *
 * The $more parameter should always be given as array, the function then
 * will strip default parameters to produce even cleaner URLs
 *
 * @param string  $id     the media file id or URL
 * @param mixed   $more   string or array with additional parameters
 * @param bool    $direct link to detail page if false
 * @param string  $sep    URL parameter separator
 * @param bool    $abs    Create an absolute URL
 * @return string
 */
function ml($id = '', $more = '', $direct = true, $sep = '&amp;', $abs = false) {
    global $conf;
    if(is_array($more)) {
        // strip defaults for shorter URLs
        if(isset($more['cache']) && $more['cache'] == 'cache') unset($more['cache']);
        if(!$more['w']) unset($more['w']);
        if(!$more['h']) unset($more['h']);
        if(isset($more['id']) && $direct) unset($more['id']);
        $more = buildURLparams($more, $sep);
    } else {
        $more = str_replace('cache=cache', '', $more); //skip default
        $more = str_replace(',,', ',', $more);
        $more = str_replace(',', $sep, $more);
    }

    if($abs) {
        $xlink = DOKU_URL;
    } else {
        $xlink = DOKU_BASE;
    }

    // external URLs are always direct without rewriting
    if(preg_match('#^(https?|ftp)://#i', $id)) {
        $xlink .= 'lib/exe/fetch.php';
        // add hash:
        $xlink .= '?hash='.substr(md5(auth_cookiesalt().$id), 0, 6);
        if($more) {
            $xlink .= $sep.$more;
            $xlink .= $sep.'media='.rawurlencode($id);
        } else {
            $xlink .= $sep.'media='.rawurlencode($id);
        }
        return $xlink;
    }

    $id = idfilter($id);

    // decide on scriptname
    if($direct) {
        if($conf['userewrite'] == 1) {
            $script = '_media';
        } else {
            $script = 'lib/exe/fetch.php';
        }
    } else {
        if($conf['userewrite'] == 1) {
            $script = '_detail';
        } else {
            $script = 'lib/exe/detail.php';
        }
    }

    // build URL based on rewrite mode
    if($conf['userewrite']) {
        $xlink .= $script.'/'.$id;
        if($more) $xlink .= '?'.$more;
    } else {
        if($more) {
            $xlink .= $script.'?'.$more;
            $xlink .= $sep.'media='.$id;
        } else {
            $xlink .= $script.'?media='.$id;
        }
    }

    return $xlink;
}

/**
 * Returns the URL to the DokuWiki base script
 *
 * Consider using wl() instead, unless you absoutely need the doku.php endpoint
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function script() {
    return DOKU_BASE.DOKU_SCRIPT;
}

/**
 * Spamcheck against wordlist
 *
 * Checks the wikitext against a list of blocked expressions
 * returns true if the text contains any bad words
 *
 * Triggers COMMON_WORDBLOCK_BLOCKED
 *
 *  Action Plugins can use this event to inspect the blocked data
 *  and gain information about the user who was blocked.
 *
 *  Event data:
 *    data['matches']  - array of matches
 *    data['userinfo'] - information about the blocked user
 *      [ip]           - ip address
 *      [user]         - username (if logged in)
 *      [mail]         - mail address (if logged in)
 *      [name]         - real name (if logged in)
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 * @author Michael Klier <chi@chimeric.de>
 * @param  string $text - optional text to check, if not given the globals are used
 * @return bool         - true if a spam word was found
 */
function checkwordblock($text = '') {
    global $TEXT;
    global $PRE;
    global $SUF;
    global $conf;
    global $INFO;

    if(!$conf['usewordblock']) return false;

    if(!$text) $text = "$PRE $TEXT $SUF";

    // we prepare the text a tiny bit to prevent spammers circumventing URL checks
    $text = preg_replace('!(\b)(www\.[\w.:?\-;,]+?\.[\w.:?\-;,]+?[\w/\#~:.?+=&%@\!\-.:?\-;,]+?)([.:?\-;,]*[^\w/\#~:.?+=&%@\!\-.:?\-;,])!i', '\1http://\2 \2\3', $text);

    $wordblocks = getWordblocks();
    // how many lines to read at once (to work around some PCRE limits)
    if(version_compare(phpversion(), '4.3.0', '<')) {
        // old versions of PCRE define a maximum of parenthesises even if no
        // backreferences are used - the maximum is 99
        // this is very bad performancewise and may even be too high still
        $chunksize = 40;
    } else {
        // read file in chunks of 200 - this should work around the
        // MAX_PATTERN_SIZE in modern PCRE
        $chunksize = 200;
    }
    while($blocks = array_splice($wordblocks, 0, $chunksize)) {
        $re = array();
        // build regexp from blocks
        foreach($blocks as $block) {
            $block = preg_replace('/#.*$/', '', $block);
            $block = trim($block);
            if(empty($block)) continue;
            $re[] = $block;
        }
        if(count($re) && preg_match('#('.join('|', $re).')#si', $text, $matches)) {
            // prepare event data
            $data['matches']        = $matches;
            $data['userinfo']['ip'] = $_SERVER['REMOTE_ADDR'];
            if($_SERVER['REMOTE_USER']) {
                $data['userinfo']['user'] = $_SERVER['REMOTE_USER'];
                $data['userinfo']['name'] = $INFO['userinfo']['name'];
                $data['userinfo']['mail'] = $INFO['userinfo']['mail'];
            }
            $callback = create_function('', 'return true;');
            return trigger_event('COMMON_WORDBLOCK_BLOCKED', $data, $callback, true);
        }
    }
    return false;
}

/**
 * Return the IP of the client
 *
 * Honours X-Forwarded-For and X-Real-IP Proxy Headers
 *
 * It returns a comma separated list of IPs if the above mentioned
 * headers are set. If the single parameter is set, it tries to return
 * a routable public address, prefering the ones suplied in the X
 * headers
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 * @param  boolean $single If set only a single IP is returned
 * @return string
 */
function clientIP($single = false) {
    $ip   = array();
    $ip[] = $_SERVER['REMOTE_ADDR'];
    if(!empty($_SERVER['HTTP_X_FORWARDED_FOR']))
        $ip = array_merge($ip, explode(',', str_replace(' ', '', $_SERVER['HTTP_X_FORWARDED_FOR'])));
    if(!empty($_SERVER['HTTP_X_REAL_IP']))
        $ip = array_merge($ip, explode(',', str_replace(' ', '', $_SERVER['HTTP_X_REAL_IP'])));

    // some IPv4/v6 regexps borrowed from Feyd
    // see: http://forums.devnetwork.net/viewtopic.php?f=38&t=53479
    $dec_octet   = '(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|[0-9])';
    $hex_digit   = '[A-Fa-f0-9]';
    $h16         = "{$hex_digit}{1,4}";
    $IPv4Address = "$dec_octet\\.$dec_octet\\.$dec_octet\\.$dec_octet";
    $ls32        = "(?:$h16:$h16|$IPv4Address)";
    $IPv6Address =
        "(?:(?:{$IPv4Address})|(?:".
            "(?:$h16:){6}$ls32".
            "|::(?:$h16:){5}$ls32".
            "|(?:$h16)?::(?:$h16:){4}$ls32".
            "|(?:(?:$h16:){0,1}$h16)?::(?:$h16:){3}$ls32".
            "|(?:(?:$h16:){0,2}$h16)?::(?:$h16:){2}$ls32".
            "|(?:(?:$h16:){0,3}$h16)?::(?:$h16:){1}$ls32".
            "|(?:(?:$h16:){0,4}$h16)?::$ls32".
            "|(?:(?:$h16:){0,5}$h16)?::$h16".
            "|(?:(?:$h16:){0,6}$h16)?::".
            ")(?:\\/(?:12[0-8]|1[0-1][0-9]|[1-9][0-9]|[0-9]))?)";

    // remove any non-IP stuff
    $cnt   = count($ip);
    $match = array();
    for($i = 0; $i < $cnt; $i++) {
        if(preg_match("/^$IPv4Address$/", $ip[$i], $match) || preg_match("/^$IPv6Address$/", $ip[$i], $match)) {
            $ip[$i] = $match[0];
        } else {
            $ip[$i] = '';
        }
        if(empty($ip[$i])) unset($ip[$i]);
    }
    $ip = array_values(array_unique($ip));
    if(!$ip[0]) $ip[0] = '0.0.0.0'; // for some strange reason we don't have a IP

    if(!$single) return join(',', $ip);

    // decide which IP to use, trying to avoid local addresses
    $ip = array_reverse($ip);
    foreach($ip as $i) {
        if(preg_match('/^(::1|[fF][eE]80:|127\.|10\.|192\.168\.|172\.((1[6-9])|(2[0-9])|(3[0-1]))\.)/', $i)) {
            continue;
        } else {
            return $i;
        }
    }
    // still here? just use the first (last) address
    return $ip[0];
}

/**
 * Check if the browser is on a mobile device
 *
 * Adapted from the example code at url below
 *
 * @link http://www.brainhandles.com/2007/10/15/detecting-mobile-browsers/#code
 */
function clientismobile() {

    if(isset($_SERVER['HTTP_X_WAP_PROFILE'])) return true;

    if(preg_match('/wap\.|\.wap/i', $_SERVER['HTTP_ACCEPT'])) return true;

    if(!isset($_SERVER['HTTP_USER_AGENT'])) return false;

    $uamatches = 'midp|j2me|avantg|docomo|novarra|palmos|palmsource|240x320|opwv|chtml|pda|windows ce|mmp\/|blackberry|mib\/|symbian|wireless|nokia|hand|mobi|phone|cdm|up\.b|audio|SIE\-|SEC\-|samsung|HTC|mot\-|mitsu|sagem|sony|alcatel|lg|erics|vx|NEC|philips|mmm|xx|panasonic|sharp|wap|sch|rover|pocket|benq|java|pt|pg|vox|amoi|bird|compal|kg|voda|sany|kdd|dbt|sendo|sgh|gradi|jb|\d\d\di|moto';

    if(preg_match("/$uamatches/i", $_SERVER['HTTP_USER_AGENT'])) return true;

    return false;
}

/**
 * Convert one or more comma separated IPs to hostnames
 *
 * If $conf['dnslookups'] is disabled it simply returns the input string
 *
 * @author Glen Harris <astfgl@iamnota.org>
 * @param  string $ips comma separated list of IP addresses
 * @return string a comma separated list of hostnames
 */
function gethostsbyaddrs($ips) {
    global $conf;
    if(!$conf['dnslookups']) return $ips;

    $hosts = array();
    $ips   = explode(',', $ips);

    if(is_array($ips)) {
        foreach($ips as $ip) {
            $hosts[] = gethostbyaddr(trim($ip));
        }
        return join(',', $hosts);
    } else {
        return gethostbyaddr(trim($ips));
    }
}

/**
 * Checks if a given page is currently locked.
 *
 * removes stale lockfiles
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function checklock($id) {
    global $conf;
    $lock = wikiLockFN($id);

    //no lockfile
    if(!@file_exists($lock)) return false;

    //lockfile expired
    if((time() - filemtime($lock)) > $conf['locktime']) {
        @unlink($lock);
        return false;
    }

    //my own lock
    list($ip, $session) = explode("\n", io_readFile($lock));
    if($ip == $_SERVER['REMOTE_USER'] || $ip == clientIP() || $session == session_id()) {
        return false;
    }

    return $ip;
}

/**
 * Lock a page for editing
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function lock($id) {
    global $conf;

    if($conf['locktime'] == 0) {
        return;
    }

    $lock = wikiLockFN($id);
    if($_SERVER['REMOTE_USER']) {
        io_saveFile($lock, $_SERVER['REMOTE_USER']);
    } else {
        io_saveFile($lock, clientIP()."\n".session_id());
    }
}

/**
 * Unlock a page if it was locked by the user
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 * @param string $id page id to unlock
 * @return bool true if a lock was removed
 */
function unlock($id) {
    $lock = wikiLockFN($id);
    if(@file_exists($lock)) {
        list($ip, $session) = explode("\n", io_readFile($lock));
        if($ip == $_SERVER['REMOTE_USER'] || $ip == clientIP() || $session == session_id()) {
            @unlink($lock);
            return true;
        }
    }
    return false;
}

/**
 * convert line ending to unix format
 *
 * @see    formText() for 2crlf conversion
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function cleanText($text) {
    $text = preg_replace("/(\015\012)|(\015)/", "\012", $text);
    return $text;
}

/**
 * Prepares text for print in Webforms by encoding special chars.
 * It also converts line endings to Windows format which is
 * pseudo standard for webforms.
 *
 * @see    cleanText() for 2unix conversion
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function formText($text) {
    $text = str_replace("\012", "\015\012", $text);
    return htmlspecialchars($text);
}

/**
 * Returns the specified local text in raw format
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function rawLocale($id, $ext = 'txt') {
    return io_readFile(localeFN($id, $ext));
}

/**
 * Returns the raw WikiText
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function rawWiki($id, $rev = '') {
    return io_readWikiPage(wikiFN($id, $rev), $id, $rev);
}

/**
 * Returns the pagetemplate contents for the ID's namespace
 *
 * @triggers COMMON_PAGETPL_LOAD
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function pageTemplate($id) {
    global $conf;

    if(is_array($id)) $id = $id[0];

    // prepare initial event data
    $data = array(
        'id'        => $id, // the id of the page to be created
        'tpl'       => '', // the text used as template
        'tplfile'   => '', // the file above text was/should be loaded from
        'doreplace' => true // should wildcard replacements be done on the text?
    );

    $evt = new Doku_Event('COMMON_PAGETPL_LOAD', $data);
    if($evt->advise_before(true)) {
        // the before event might have loaded the content already
        if(empty($data['tpl'])) {
            // if the before event did not set a template file, try to find one
            if(empty($data['tplfile'])) {
                $path = dirname(wikiFN($id));
                if(@file_exists($path.'/_template.txt')) {
                    $data['tplfile'] = $path.'/_template.txt';
                } else {
                    // search upper namespaces for templates
                    $len = strlen(rtrim($conf['datadir'], '/'));
                    while(strlen($path) >= $len) {
                        if(@file_exists($path.'/__template.txt')) {
                            $data['tplfile'] = $path.'/__template.txt';
                            break;
                        }
                        $path = substr($path, 0, strrpos($path, '/'));
                    }
                }
            }
            // load the content
            $data['tpl'] = io_readFile($data['tplfile']);
        }
        if($data['doreplace']) parsePageTemplate($data);
    }
    $evt->advise_after();
    unset($evt);

    return $data['tpl'];
}

/**
 * Performs common page template replacements
 * This works on data from COMMON_PAGETPL_LOAD
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function parsePageTemplate(&$data) {
    /**
     * @var string $id        the id of the page to be created
     * @var string $tpl       the text used as template
     * @var string $tplfile   the file above text was/should be loaded from
     * @var bool   $doreplace should wildcard replacements be done on the text?
     */
    extract($data);

    global $USERINFO;
    global $conf;

    // replace placeholders
    $file = noNS($id);
    $page = strtr($file, $conf['sepchar'], ' ');

    $tpl = str_replace(
        array(
             '@ID@',
             '@NS@',
             '@FILE@',
             '@!FILE@',
             '@!FILE!@',
             '@PAGE@',
             '@!PAGE@',
             '@!!PAGE@',
             '@!PAGE!@',
             '@USER@',
             '@NAME@',
             '@MAIL@',
             '@DATE@',
        ),
        array(
             $id,
             getNS($id),
             $file,
             utf8_ucfirst($file),
             utf8_strtoupper($file),
             $page,
             utf8_ucfirst($page),
             utf8_ucwords($page),
             utf8_strtoupper($page),
             $_SERVER['REMOTE_USER'],
             $USERINFO['name'],
             $USERINFO['mail'],
             $conf['dformat'],
        ), $tpl
    );

    // we need the callback to work around strftime's char limit
    $tpl         = preg_replace_callback('/%./', create_function('$m', 'return strftime($m[0]);'), $tpl);
    $data['tpl'] = $tpl;
    return $tpl;
}

/**
 * Returns the raw Wiki Text in three slices.
 *
 * The range parameter needs to have the form "from-to"
 * and gives the range of the section in bytes - no
 * UTF-8 awareness is needed.
 * The returned order is prefix, section and suffix.
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function rawWikiSlices($range, $id, $rev = '') {
    $text = io_readWikiPage(wikiFN($id, $rev), $id, $rev);

    // Parse range
    list($from, $to) = explode('-', $range, 2);
    // Make range zero-based, use defaults if marker is missing
    $from = !$from ? 0 : ($from - 1);
    $to   = !$to ? strlen($text) : ($to - 1);

    $slices[0] = substr($text, 0, $from);
    $slices[1] = substr($text, $from, $to - $from);
    $slices[2] = substr($text, $to);
    return $slices;
}

/**
 * Joins wiki text slices
 *
 * function to join the text slices.
 * When the pretty parameter is set to true it adds additional empty
 * lines between sections if needed (used on saving).
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function con($pre, $text, $suf, $pretty = false) {
    if($pretty) {
        if($pre !== '' && substr($pre, -1) !== "\n" &&
            substr($text, 0, 1) !== "\n"
        ) {
            $pre .= "\n";
        }
        if($suf !== '' && substr($text, -1) !== "\n" &&
            substr($suf, 0, 1) !== "\n"
        ) {
            $text .= "\n";
        }
    }

    return $pre.$text.$suf;
}

/**
 * Saves a wikitext by calling io_writeWikiPage.
 * Also directs changelog and attic updates.
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 * @author Ben Coburn <btcoburn@silicodon.net>
 */
function saveWikiText($id, $text, $summary, $minor = false) {
    /* Note to developers:
       This code is subtle and delicate. Test the behavior of
       the attic and changelog with dokuwiki and external edits
       after any changes. External edits change the wiki page
       directly without using php or dokuwiki.
     */
    global $conf;
    global $lang;
    global $REV;
    // ignore if no changes were made
    if($text == rawWiki($id, '')) {
        return;
    }

    $file        = wikiFN($id);
    $old         = @filemtime($file); // from page
    $wasRemoved  = (trim($text) == ''); // check for empty or whitespace only
    $wasCreated  = !@file_exists($file);
    $wasReverted = ($REV == true);
    $newRev      = false;
    $oldRev      = getRevisions($id, -1, 1, 1024); // from changelog
    $oldRev      = (int) (empty($oldRev) ? 0 : $oldRev[0]);
    if(!@file_exists(wikiFN($id, $old)) && @file_exists($file) && $old >= $oldRev) {
        // add old revision to the attic if missing
        saveOldRevision($id);
        // add a changelog entry if this edit came from outside dokuwiki
        if($old > $oldRev) {
            addLogEntry($old, $id, DOKU_CHANGE_TYPE_EDIT, $lang['external_edit'], '', array('ExternalEdit'=> true));
            // remove soon to be stale instructions
            $cache = new cache_instructions($id, $file);
            $cache->removeCache();
        }
    }

    if($wasRemoved) {
        // Send "update" event with empty data, so plugins can react to page deletion
        $data = array(array($file, '', false), getNS($id), noNS($id), false);
        trigger_event('IO_WIKIPAGE_WRITE', $data);
        // pre-save deleted revision
        @touch($file);
        clearstatcache();
        $newRev = saveOldRevision($id);
        // remove empty file
        @unlink($file);
        // don't remove old meta info as it should be saved, plugins can use IO_WIKIPAGE_WRITE for removing their metadata...
        // purge non-persistant meta data
        p_purge_metadata($id);
        $del = true;
        // autoset summary on deletion
        if(empty($summary)) $summary = $lang['deleted'];
        // remove empty namespaces
        io_sweepNS($id, 'datadir');
        io_sweepNS($id, 'mediadir');
    } else {
        // save file (namespace dir is created in io_writeWikiPage)
        io_writeWikiPage($file, $text, $id);
        // pre-save the revision, to keep the attic in sync
        $newRev = saveOldRevision($id);
        $del    = false;
    }

    // select changelog line type
    $extra = '';
    $type  = DOKU_CHANGE_TYPE_EDIT;
    if($wasReverted) {
        $type  = DOKU_CHANGE_TYPE_REVERT;
        $extra = $REV;
    } else if($wasCreated) {
        $type = DOKU_CHANGE_TYPE_CREATE;
    } else if($wasRemoved) {
        $type = DOKU_CHANGE_TYPE_DELETE;
    } else if($minor && $conf['useacl'] && $_SERVER['REMOTE_USER']) {
        $type = DOKU_CHANGE_TYPE_MINOR_EDIT;
    } //minor edits only for logged in users

    addLogEntry($newRev, $id, $type, $summary, $extra);
    // send notify mails
    notify($id, 'admin', $old, $summary, $minor);
    notify($id, 'subscribers', $old, $summary, $minor);

    // update the purgefile (timestamp of the last time anything within the wiki was changed)
    io_saveFile($conf['cachedir'].'/purgefile', time());

    // if useheading is enabled, purge the cache of all linking pages
    if(useHeading('content')) {
        $pages = ft_backlinks($id);
        foreach($pages as $page) {
            $cache = new cache_renderer($page, wikiFN($page), 'xhtml');
            $cache->removeCache();
        }
    }
}

/**
 * moves the current version to the attic and returns its
 * revision date
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function saveOldRevision($id) {
    global $conf;
    $oldf = wikiFN($id);
    if(!@file_exists($oldf)) return '';
    $date = filemtime($oldf);
    $newf = wikiFN($id, $date);
    io_writeWikiPage($newf, rawWiki($id), $id, $date);
    return $date;
}

/**
 * Sends a notify mail on page change or registration
 *
 * @param string     $id       The changed page
 * @param string     $who      Who to notify (admin|subscribers|register)
 * @param int|string $rev Old page revision
 * @param string     $summary  What changed
 * @param boolean    $minor    Is this a minor edit?
 * @param array      $replace  Additional string substitutions, @KEY@ to be replaced by value
 *
 * @return bool
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function notify($id, $who, $rev = '', $summary = '', $minor = false, $replace = array()) {
    global $lang;
    global $conf;
    global $INFO;
    global $DIFF_INLINESTYLES;

    // decide if there is something to do, eg. whom to mail
    if($who == 'admin') {
        if(empty($conf['notify'])) return false; //notify enabled?
        $text = rawLocale('mailtext');
        $to   = $conf['notify'];
        $bcc  = '';
    } elseif($who == 'subscribers') {
        if(!actionOK('subscribe')) return false; //subscribers enabled?
        if($conf['useacl'] && $_SERVER['REMOTE_USER'] && $minor) return false; //skip minors
        $data = array('id' => $id, 'addresslist' => '', 'self' => false);
        trigger_event(
            'COMMON_NOTIFY_ADDRESSLIST', $data,
            array(new Subscription(), 'notifyaddresses')
        );
        $bcc = $data['addresslist'];
        if(empty($bcc)) return false;
        $to   = '';
        $text = rawLocale('subscr_single');
    } elseif($who == 'register') {
        if(empty($conf['registernotify'])) return false;
        $text = rawLocale('registermail');
        $to   = $conf['registernotify'];
        $bcc  = '';
    } else {
        return false; //just to be safe
    }

    // prepare replacements (keys not set in hrep will be taken from trep)
    $trep = array(
        'NEWPAGE' => wl($id, '', true, '&'),
        'PAGE'    => $id,
        'SUMMARY' => $summary
    );
    $trep = array_merge($trep, $replace);
    $hrep = array();

    // prepare content
    if($who == 'register') {
        $subject = $lang['mail_new_user'].' '.$summary;
    } elseif($rev) {
        $subject         = $lang['mail_changed'].' '.$id;
        $trep['OLDPAGE'] = wl($id, "rev=$rev", true, '&');
        $df              = new Diff(explode("\n", rawWiki($id, $rev)),
                                    explode("\n", rawWiki($id)));
        $dformat         = new UnifiedDiffFormatter();
        $tdiff           = $dformat->format($df);

        $DIFF_INLINESTYLES = true;
        $dformat           = new InlineDiffFormatter();
        $hdiff             = $dformat->format($df);
        $hdiff             = '<table>'.$hdiff.'</table>';
        $DIFF_INLINESTYLES = false;
    } else {
        $subject         = $lang['mail_newpage'].' '.$id;
        $trep['OLDPAGE'] = '---';
        $tdiff           = rawWiki($id);
        $hdiff           = nl2br(hsc($tdiff));
    }
    $trep['DIFF'] = $tdiff;
    $hrep['DIFF'] = $hdiff;

    // send mail
    $mail = new Mailer();
    $mail->to($to);
    $mail->bcc($bcc);
    $mail->subject($subject);
    $mail->setBody($text, $trep, $hrep);
    if($who == 'subscribers') {
        $mail->setHeader(
            'List-Unsubscribe',
            '<'.wl($id, array('do'=> 'subscribe'), true, '&').'>',
            false
        );
    }
    return $mail->send();
}

/**
 * extracts the query from a search engine referrer
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 * @author Todd Augsburger <todd@rollerorgans.com>
 */
function getGoogleQuery() {
    if(!isset($_SERVER['HTTP_REFERER'])) {
        return '';
    }
    $url = parse_url($_SERVER['HTTP_REFERER']);

    // only handle common SEs
    if(!preg_match('/(google|bing|yahoo|ask|duckduckgo|babylon|aol|yandex)/',$url['host'])) return '';

    $query = array();
    // temporary workaround against PHP bug #49733
    // see http://bugs.php.net/bug.php?id=49733
    if(UTF8_MBSTRING) $enc = mb_internal_encoding();
    parse_str($url['query'], $query);
    if(UTF8_MBSTRING) mb_internal_encoding($enc);

    $q = '';
    if(isset($query['q'])){
        $q = $query['q'];
    }elseif(isset($query['p'])){
        $q = $query['p'];
    }elseif(isset($query['query'])){
        $q = $query['query'];
    }
    $q = trim($q);

    if(!$q) return '';
    $q = preg_split('/[\s\'"\\\\`()\]\[?:!\.{};,#+*<>\\/]+/', $q, -1, PREG_SPLIT_NO_EMPTY);
    return $q;
}

/**
 * Try to set correct locale
 *
 * @deprecated No longer used
 * @author     Andreas Gohr <andi@splitbrain.org>
 */
function setCorrectLocale() {
    global $conf;
    global $lang;

    $enc = strtoupper($lang['encoding']);
    foreach($lang['locales'] as $loc) {
        //try locale
        if(@setlocale(LC_ALL, $loc)) return;
        //try loceale with encoding
        if(@setlocale(LC_ALL, "$loc.$enc")) return;
    }
    //still here? try to set from environment
    @setlocale(LC_ALL, "");
}

/**
 * Return the human readable size of a file
 *
 * @param       int    $size   A file size
 * @param       int    $dec    A number of decimal places
 * @author      Martin Benjamin <b.martin@cybernet.ch>
 * @author      Aidan Lister <aidan@php.net>
 * @version     1.0.0
 */
function filesize_h($size, $dec = 1) {
    $sizes = array('B', 'KB', 'MB', 'GB');
    $count = count($sizes);
    $i     = 0;

    while($size >= 1024 && ($i < $count - 1)) {
        $size /= 1024;
        $i++;
    }

    return round($size, $dec).' '.$sizes[$i];
}

/**
 * Return the given timestamp as human readable, fuzzy age
 *
 * @author Andreas Gohr <gohr@cosmocode.de>
 */
function datetime_h($dt) {
    global $lang;

    $ago = time() - $dt;
    if($ago > 24 * 60 * 60 * 30 * 12 * 2) {
        return sprintf($lang['years'], round($ago / (24 * 60 * 60 * 30 * 12)));
    }
    if($ago > 24 * 60 * 60 * 30 * 2) {
        return sprintf($lang['months'], round($ago / (24 * 60 * 60 * 30)));
    }
    if($ago > 24 * 60 * 60 * 7 * 2) {
        return sprintf($lang['weeks'], round($ago / (24 * 60 * 60 * 7)));
    }
    if($ago > 24 * 60 * 60 * 2) {
        return sprintf($lang['days'], round($ago / (24 * 60 * 60)));
    }
    if($ago > 60 * 60 * 2) {
        return sprintf($lang['hours'], round($ago / (60 * 60)));
    }
    if($ago > 60 * 2) {
        return sprintf($lang['minutes'], round($ago / (60)));
    }
    return sprintf($lang['seconds'], $ago);
}

/**
 * Wraps around strftime but provides support for fuzzy dates
 *
 * The format default to $conf['dformat']. It is passed to
 * strftime - %f can be used to get the value from datetime_h()
 *
 * @see datetime_h
 * @author Andreas Gohr <gohr@cosmocode.de>
 */
function dformat($dt = null, $format = '') {
    global $conf;

    if(is_null($dt)) $dt = time();
    $dt = (int) $dt;
    if(!$format) $format = $conf['dformat'];

    $format = str_replace('%f', datetime_h($dt), $format);
    return strftime($format, $dt);
}

/**
 * Formats a timestamp as ISO 8601 date
 *
 * @author <ungu at terong dot com>
 * @link http://www.php.net/manual/en/function.date.php#54072
 * @param int $int_date: current date in UNIX timestamp
 * @return string
 */
function date_iso8601($int_date) {
    $date_mod     = date('Y-m-d\TH:i:s', $int_date);
    $pre_timezone = date('O', $int_date);
    $time_zone    = substr($pre_timezone, 0, 3).":".substr($pre_timezone, 3, 2);
    $date_mod .= $time_zone;
    return $date_mod;
}

/**
 * return an obfuscated email address in line with $conf['mailguard'] setting
 *
 * @author Harry Fuecks <hfuecks@gmail.com>
 * @author Christopher Smith <chris@jalakai.co.uk>
 */
function obfuscate($email) {
    global $conf;

    switch($conf['mailguard']) {
        case 'visible' :
            $obfuscate = array('@' => ' [at] ', '.' => ' [dot] ', '-' => ' [dash] ');
            return strtr($email, $obfuscate);

        case 'hex' :
            $encode = '';
            $len    = strlen($email);
            for($x = 0; $x < $len; $x++) {
                $encode .= '&#x'.bin2hex($email{$x}).';';
            }
            return $encode;

        case 'none' :
        default :
            return $email;
    }
}

/**
 * Removes quoting backslashes
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function unslash($string, $char = "'") {
    return str_replace('\\'.$char, $char, $string);
}

/**
 * Convert php.ini shorthands to byte
 *
 * @author <gilthans dot NO dot SPAM at gmail dot com>
 * @link   http://de3.php.net/manual/en/ini.core.php#79564
 */
function php_to_byte($v) {
    $l   = substr($v, -1);
    $ret = substr($v, 0, -1);
    switch(strtoupper($l)) {
        case 'P':
            $ret *= 1024;
        case 'T':
            $ret *= 1024;
        case 'G':
            $ret *= 1024;
        case 'M':
            $ret *= 1024;
        case 'K':
            $ret *= 1024;
            break;
        default;
            $ret *= 10;
            break;
    }
    return $ret;
}

/**
 * Wrapper around preg_quote adding the default delimiter
 */
function preg_quote_cb($string) {
    return preg_quote($string, '/');
}

/**
 * Shorten a given string by removing data from the middle
 *
 * You can give the string in two parts, the first part $keep
 * will never be shortened. The second part $short will be cut
 * in the middle to shorten but only if at least $min chars are
 * left to display it. Otherwise it will be left off.
 *
 * @param string $keep   the part to keep
 * @param string $short  the part to shorten
 * @param int    $max    maximum chars you want for the whole string
 * @param int    $min    minimum number of chars to have left for middle shortening
 * @param string $char   the shortening character to use
 * @return string
 */
function shorten($keep, $short, $max, $min = 9, $char = '…') {
    $max = $max - utf8_strlen($keep);
    if($max < $min) return $keep;
    $len = utf8_strlen($short);
    if($len <= $max) return $keep.$short;
    $half = floor($max / 2);
    return $keep.utf8_substr($short, 0, $half - 1).$char.utf8_substr($short, $len - $half);
}

/**
 * Return the users realname or e-mail address for use
 * in page footer and recent changes pages
 *
 * @author Andy Webber <dokuwiki AT andywebber DOT com>
 */
function editorinfo($username) {
    global $conf;
    global $auth;

    switch($conf['showuseras']) {
        case 'username':
        case 'email':
        case 'email_link':
            if($auth) $info = $auth->getUserData($username);
            break;
        default:
            return hsc($username);
    }

    if(isset($info) && $info) {
        switch($conf['showuseras']) {
            case 'username':
                return hsc($info['name']);
            case 'email':
                return obfuscate($info['mail']);
            case 'email_link':
                $mail = obfuscate($info['mail']);
                return '<a href="mailto:'.$mail.'">'.$mail.'</a>';
            default:
                return hsc($username);
        }
    } else {
        return hsc($username);
    }
}

/**
 * Returns the path to a image file for the currently chosen license.
 * When no image exists, returns an empty string
 *
 * @author Andreas Gohr <andi@splitbrain.org>
 * @param  string $type - type of image 'badge' or 'button'
 * @return string
 */
function license_img($type) {
    global $license;
    global $conf;
    if(!$conf['license']) return '';
    if(!is_array($license[$conf['license']])) return '';
    $lic   = $license[$conf['license']];
    $try   = array();
    $try[] = 'lib/images/license/'.$type.'/'.$conf['license'].'.png';
    $try[] = 'lib/images/license/'.$type.'/'.$conf['license'].'.gif';
    if(substr($conf['license'], 0, 3) == 'cc-') {
        $try[] = 'lib/images/license/'.$type.'/cc.png';
    }
    foreach($try as $src) {
        if(@file_exists(DOKU_INC.$src)) return $src;
    }
    return '';
}

/**
 * Checks if the given amount of memory is available
 *
 * If the memory_get_usage() function is not available the
 * function just assumes $bytes of already allocated memory
 *
 * @author Filip Oscadal <webmaster@illusionsoftworks.cz>
 * @author Andreas Gohr <andi@splitbrain.org>
 *
 * @param  int $mem  Size of memory you want to allocate in bytes
 * @param int  $bytes
 * @internal param int $used already allocated memory (see above)
 * @return bool
 */
function is_mem_available($mem, $bytes = 1048576) {
    $limit = trim(ini_get('memory_limit'));
    if(empty($limit)) return true; // no limit set!

    // parse limit to bytes
    $limit = php_to_byte($limit);

    // get used memory if possible
    if(function_exists('memory_get_usage')) {
        $used = memory_get_usage();
    } else {
        $used = $bytes;
    }

    if($used + $mem > $limit) {
        return false;
    }

    return true;
}

/**
 * Send a HTTP redirect to the browser
 *
 * Works arround Microsoft IIS cookie sending bug. Exits the script.
 *
 * @link   http://support.microsoft.com/kb/q176113/
 * @author Andreas Gohr <andi@splitbrain.org>
 */
function send_redirect($url) {
    //are there any undisplayed messages? keep them in session for display
    global $MSG;
    if(isset($MSG) && count($MSG) && !defined('NOSESSION')) {
        //reopen session, store data and close session again
        @session_start();
        $_SESSION[DOKU_COOKIE]['msg'] = $MSG;
    }

    // always close the session
    session_write_close();

    // work around IE bug
    // http://www.ianhoar.com/2008/11/16/internet-explorer-6-and-redirected-anchor-links/
    list($url, $hash) = explode('#', $url);
    if($hash) {
        if(strpos($url, '?')) {
            $url = $url.'&#'.$hash;
        } else {
            $url = $url.'?&#'.$hash;
        }
    }

    // check if running on IIS < 6 with CGI-PHP
    if(isset($_SERVER['SERVER_SOFTWARE']) && isset($_SERVER['GATEWAY_INTERFACE']) &&
        (strpos($_SERVER['GATEWAY_INTERFACE'], 'CGI') !== false) &&
        (preg_match('|^Microsoft-IIS/(\d)\.\d$|', trim($_SERVER['SERVER_SOFTWARE']), $matches)) &&
        $matches[1] < 6
    ) {
        header('Refresh: 0;url='.$url);
    } else {
        header('Location: '.$url);
    }
    exit;
}

/**
 * Validate a value using a set of valid values
 *
 * This function checks whether a specified value is set and in the array
 * $valid_values. If not, the function returns a default value or, if no
 * default is specified, throws an exception.
 *
 * @param string $param        The name of the parameter
 * @param array  $valid_values A set of valid values; Optionally a default may
 *                             be marked by the key “default”.
 * @param array  $array        The array containing the value (typically $_POST
 *                             or $_GET)
 * @param string $exc          The text of the raised exception
 *
 * @throws Exception
 * @return mixed
 * @author Adrian Lang <lang@cosmocode.de>
 */
function valid_input_set($param, $valid_values, $array, $exc = '') {
    if(isset($array[$param]) && in_array($array[$param], $valid_values)) {
        return $array[$param];
    } elseif(isset($valid_values['default'])) {
        return $valid_values['default'];
    } else {
        throw new Exception($exc);
    }
}

/**
 * Read a preference from the DokuWiki cookie
 */
function get_doku_pref($pref, $default) {
    if(strpos($_COOKIE['DOKU_PREFS'], $pref) !== false) {
        $parts = explode('#', $_COOKIE['DOKU_PREFS']);
        $cnt   = count($parts);
        for($i = 0; $i < $cnt; $i += 2) {
            if($parts[$i] == $pref) {
                return $parts[$i + 1];
            }
        }
    }
    return $default;
}

//Setup VIM: ex: et ts=2 :