[squirrelmail.git] / functions / global.php

<?php

/**
 * global.php
 *
 * This includes code to update < 4.1.0 globals to the newer format
 * It also has some session register functions that work across various
 * php versions.
 *
 * @copyright &copy; 1999-2007 The SquirrelMail Project Team
 * @license http://opensource.org/licenses/gpl-license.php GNU Public License
 * @version $Id$
 * @package squirrelmail
 */

/**
 */
define('SQ_INORDER',0);
define('SQ_GET',1);
define('SQ_POST',2);
define('SQ_SESSION',3);
define('SQ_COOKIE',4);
define('SQ_SERVER',5);
define('SQ_FORM',6);


/**
 * returns true if current php version is at mimimum a.b.c
 *
 * Called: check_php_version(4,1)
 * @param int a major version number
 * @param int b minor version number
 * @param int c release number
 * @return bool
 */
function check_php_version ($a = '0', $b = '0', $c = '0')
{
    return version_compare ( PHP_VERSION, "$a.$b.$c", 'ge' );
}

/**
 * returns true if the current internal SM version is at minimum a.b.c
 * These are plain integer comparisons, as our internal version is
 * constructed by us, as an array of 3 ints.
 *
 * Called: check_sm_version(1,3,3)
 * @param int a major version number
 * @param int b minor version number
 * @param int c release number
 * @return bool
 */
function check_sm_version($a = 0, $b = 0, $c = 0)
{
    global $SQM_INTERNAL_VERSION;
    if ( !isset($SQM_INTERNAL_VERSION) ||
         $SQM_INTERNAL_VERSION[0] < $a ||
         ( $SQM_INTERNAL_VERSION[0] == $a &&
           $SQM_INTERNAL_VERSION[1] < $b) ||
         ( $SQM_INTERNAL_VERSION[0] == $a &&
           $SQM_INTERNAL_VERSION[1] == $b &&
           $SQM_INTERNAL_VERSION[2] < $c ) ) {
        return FALSE;
    }
    return TRUE;
}


/**
 * Recursively strip slashes from the values of an array.
 * @param array array the array to strip, passed by reference
 * @return void
 */
function sqstripslashes(&$array) {
    if(count($array) > 0) {
        foreach ($array as $index=>$value) {
            if (is_array($array[$index])) {
                sqstripslashes($array[$index]);
            }
            else {
                $array[$index] = stripslashes($value);
            }
        }
    }
}

/**
 * Squelch error output to screen (only) for the given function.
 * If the SquirrelMail debug mode SM_DEBUG_MODE_ADVANCED is not 
 * enabled, error output will not go to the log, either.
 *
 * This provides an alternative to the @ error-suppression
 * operator where errors will not be shown in the interface
 * but will show up in the server log file (assuming the
 * administrator has configured PHP logging).
 *
 * @since 1.4.12 and 1.5.2
 *
 * @param string $function The function to be executed
 * @param array  $args     The arguments to be passed to the function
 *                         (OPTIONAL; default no arguments)
 *                         NOTE: The caller must take extra action if
 *                               the function being called is supposed
 *                               to use any of the parameters by
 *                               reference.  In the following example,
 *                               $x is passed by reference and $y is
 *                               passed by value to the "my_func"
 *                               function.
 * sq_call_function_suppress_errors('my_func', array(&$x, $y));
 *
 * @return mixed The return value, if any, of the function being
 *               executed will be returned.
 *
 */
function sq_call_function_suppress_errors($function, $args=NULL) {
   global $sm_debug_mode;

   $display_errors = ini_get('display_errors');
   ini_set('display_errors', '0');

   // if advanced debug mode isn't enabled, don't log the error, either
   //
   if (!($sm_debug_mode & SM_DEBUG_MODE_ADVANCED))
      $error_reporting = error_reporting(0);

   $ret = call_user_func_array($function, $args);

   if (!($sm_debug_mode & SM_DEBUG_MODE_ADVANCED))
      error_reporting($error_reporting);

   ini_set('display_errors', $display_errors);
   return $ret;
}

/**
 * Add a variable to the session.
 * @param mixed $var the variable to register
 * @param string $name the name to refer to this variable
 * @return void
 */
function sqsession_register ($var, $name) {

    sqsession_is_active();

    $_SESSION[$name] = $var;
}

/**
 * Delete a variable from the session.
 * @param string $name the name of the var to delete
 * @return void
 */
function sqsession_unregister ($name) {

    sqsession_is_active();

    unset($_SESSION[$name]);

    session_unregister("$name");
}

/**
 * Checks to see if a variable has already been registered
 * in the session.
 * @param string $name the name of the var to check
 * @return bool whether the var has been registered
 */
function sqsession_is_registered ($name) {
    $test_name = &$name;
    $result = false;

    if (isset($_SESSION[$test_name])) {
        $result = true;
    }

    return $result;
}


/**
  * Retrieves a form variable, from a set of possible similarly named
  * form variables, based on finding a different, single field.  This
  * is intended to allow more than one same-named inputs in a single
  * <form>, where the submit button that is clicked tells us which
  * input we should retrieve.  An example is if we have:
  *     <select name="startMessage_1">
  *     <select name="startMessage_2">
  *     <input type="submit" name="form_submit_1" />
  *     <input type="submit" name="form_submit_2" />
  * and we want to know which one of the select inputs should be
  * returned as $startMessage (without the suffix!), this function
  * decides by looking for either "form_submit_1" or "form_submit_2"
  * (both should not appear).  In this example, $name should be
  * "startMessage" and $indicator_field should be "form_submit".
  *
  * NOTE that form widgets must be named with the suffix "_1", "_2", "_3"
  *      and so on, or this function will not work.
  *
  * If more than one of the indicator fields is found, the first one
  * (numerically) will win.
  *
  * If an indicator field is found without a matching input ($name)
  * field, FALSE is returned.
  *
  * If no indicator fields are found, a field of $name *without* any
  * suffix is searched for (but only if $fallback_no_suffix is TRUE),
  * and if not found, FALSE is ultimately returned.
  *
  * It should also be possible to use the same string for both
  * $name and $indicator_field to look for the first possible
  * widget with a suffix that can be found (and possibly fallback
  * to a widget without a suffix).
  *
  * @param string name the name of the var to search
  * @param mixed value the variable to return
  * @param string indicator_field the name of the field upon which to base
  *                               our decision upon (see above)
  * @param int search constant defining where to look
  * @param bool fallback_no_suffix whether or not to look for $name with
  *                                no suffix when nothing else is found
  * @param mixed default the value to assign to $value when nothing is found
  * @param int typecast force variable to be cast to given type (please
  *                     use SQ_TYPE_XXX constants or set to FALSE (default)
  *                     to leave variable type unmolested)
  *
  * @return bool whether variable is found.
  */
function sqGetGlobalVarMultiple($name, &$value, $indicator_field,
                                $search = SQ_INORDER,
                                $fallback_no_suffix=TRUE, $default=NULL,
                                $typecast=FALSE) {

    // Set arbitrary max limit -- should be much lower except on the
    // search results page, if there are many (50 or more?) mailboxes
    // shown, this may not be high enough.  Is there some way we should
    // automate this value?
    //
    $max_form_search = 100;

    for ($i = 1; $i <= $max_form_search; $i++) {
        if (sqGetGlobalVar($indicator_field . '_' . $i, $temp, $search)) {
            return sqGetGlobalVar($name . '_' . $i, $value, $search, $default, $typecast);
        }
    }


    // no indicator field found; just try without suffix if allowed
    //
    if ($fallback_no_suffix) {
        return sqGetGlobalVar($name, $value, $search, $default, $typecast);
    }


    // no dice, set default and return FALSE
    //
    if (!is_null($default)) {
        $value = $default;
    }
    return FALSE;

}


/**
 * Search for the var $name in $_SESSION, $_POST, $_GET, $_COOKIE, or $_SERVER
 * and set it in provided var.
 *
 * If $search is not provided, or if it is SQ_INORDER, it will search $_SESSION,
 * then $_POST, then $_GET. If $search is SQ_FORM it will search $_POST and
 * $_GET.  Otherwise, use one of the defined constants to look for a var in one
 * place specifically.
 *
 * Note: $search is an int value equal to one of the constants defined above.
 *
 * Example:
 * sqgetGlobalVar('username',$username,SQ_SESSION);
 * // No quotes around last param, it's a constant - not a string!
 *
 * @param string name the name of the var to search
 * @param mixed value the variable to return
 * @param int search constant defining where to look
 * @param mixed default the value to assign to $value when nothing is found
 * @param int typecast force variable to be cast to given type (please
 *                     use SQ_TYPE_XXX constants or set to FALSE (default)
 *                     to leave variable type unmolested)
 *
 * @return bool whether variable is found.
 */
function sqgetGlobalVar($name, &$value, $search = SQ_INORDER, $default = NULL, $typecast = false) {

    $result = false;

    switch ($search) {
        /* we want the default case to be first here,
           so that if a valid value isn't specified,
           all three arrays will be searched. */
      default:
      case SQ_INORDER: // check session, post, get
      case SQ_SESSION:
        if( isset($_SESSION[$name]) ) {
            $value = $_SESSION[$name];
            $result = TRUE;
            break;
        } elseif ( $search == SQ_SESSION ) {
            break;
        }
      case SQ_FORM:   // check post, get
      case SQ_POST:
        if( isset($_POST[$name]) ) {
            $value = $_POST[$name];
            $result = TRUE;
            break;
        } elseif ( $search == SQ_POST ) {
          break;
        }
      case SQ_GET:
        if ( isset($_GET[$name]) ) {
            $value = $_GET[$name];
            $result = TRUE;
            break;
        }
        /* NO IF HERE. FOR SQ_INORDER CASE, EXIT after GET */
        break;
      case SQ_COOKIE:
        if ( isset($_COOKIE[$name]) ) {
            $value = $_COOKIE[$name];
            $result = TRUE;
            break;
        }
        break;
      case SQ_SERVER:
        if ( isset($_SERVER[$name]) ) {
            $value = $_SERVER[$name];
            $result = TRUE;
            break;
        }
        break;
    }
    if ($result && $typecast) {
        switch ($typecast) {
            case SQ_TYPE_INT: $value = (int) $value; break;
            case SQ_TYPE_STRING: $value = (string) $value; break;
            case SQ_TYPE_BOOL: $value = (bool) $value; break;
            default: break;
        }
    } else if (!$result && !is_null($default)) {
        $value = $default;
    }
    return $result;
}

/**
 * Deletes an existing session, more advanced than the standard PHP
 * session_destroy(), it explicitly deletes the cookies and global vars.
 *
 * WARNING: Older PHP versions have some issues with session management.
 * See http://bugs.php.net/11643 (warning, spammed bug tracker) and
 * http://bugs.php.net/13834. SID constant is not destroyed in PHP 4.1.2,
 * 4.2.3 and maybe other versions. If you restart session after session
 * is destroyed, affected PHP versions produce PHP notice. Bug should
 * be fixed only in 4.3.0
 */
function sqsession_destroy() {

    /*
     * php.net says we can kill the cookie by setting just the name:
     * http://www.php.net/manual/en/function.setcookie.php
     * maybe this will help fix the session merging again.
     *
     * Changed the theory on this to kill the cookies first starting
     * a new session will provide a new session for all instances of
     * the browser, we don't want that, as that is what is causing the
     * merging of sessions.
     */

    global $base_uri, $_COOKIE, $_SESSION;

    if (isset($_COOKIE[session_name()]) && session_name()) sqsetcookie(session_name(), '', 0, $base_uri);
    if (isset($_COOKIE['username']) && $_COOKIE['username']) sqsetcookie('username','',0,$base_uri);
    if (isset($_COOKIE['key']) && $_COOKIE['key']) sqsetcookie('key','',0,$base_uri);

    $sessid = session_id();
    if (!empty( $sessid )) {
        $_SESSION = array();
        @session_destroy();
    }
}

/**
 * Function to verify a session has been started.  If it hasn't
 * start a session up.  php.net doesn't tell you that $_SESSION
 * (even though autoglobal), is not created unless a session is
 * started, unlike $_POST, $_GET and such
 * Update: (see #1685031) the session ID is left over after the
 * session is closed in some PHP setups; this function just becomes
 * a passthru to sqsession_start(), but leaving old code in for
 * edification.
 */
function sqsession_is_active() {
    //$sessid = session_id();
    //if ( empty( $sessid ) ) {
        sqsession_start();
    //}
}

/**
 * Function to start the session and store the cookie with the session_id as
 * HttpOnly cookie which means that the cookie isn't accessible by javascript
 * (IE6 only)
 * Note that as sqsession_is_active() no longer discriminates as to when 
 * it calls this function, session_start() has to have E_NOTICE suppression
 * (thus the @ sign).
 */
function sqsession_start() {
    global $base_uri;

    sq_call_function_suppress_errors('session_start');
    // was: @session_start();
    $session_id = session_id();

    // session_starts sets the sessionid cookie buth without the httponly var
    // setting the cookie again sets the httponly cookie attribute
    sqsetcookie(session_name(),$session_id,false,$base_uri);
}


/**
 * Set a cookie
 * @param string  $sName     The name of the cookie.
 * @param string  $sValue    The value of the cookie.
 * @param int     $iExpire   The time the cookie expires. This is a Unix timestamp so is in number of seconds since the epoch.
 * @param string  $sPath     The path on the server in which the cookie will be available on.
 * @param string  $sDomain   The domain that the cookie is available.
 * @param boolean $bSecure   Indicates that the cookie should only be transmitted over a secure HTTPS connection.
 * @param boolean $bHttpOnly Disallow JS to access the cookie (IE6 only)
 * @return void
 */
function sqsetcookie($sName,$sValue='deleted',$iExpire=0,$sPath="",$sDomain="",$bSecure=false,$bHttpOnly=true) {
    // if we have a secure connection then limit the cookies to https only.
    if ($sName && isset($_SERVER['HTTPS']) && $_SERVER['HTTPS']) {
        $bSecure = true;
    }

    // admin config can override the restriction of secure-only cookies
    global $only_secure_cookies;
    if (!$only_secure_cookies)
        $bSecure = false;

    if (false && check_php_version(5,2)) {
       // php 5 supports the httponly attribute in setcookie, but because setcookie seems a bit
       // broken we use the header function for php 5.2 as well. We might change that later.
       //setcookie($sName,$sValue,(int) $iExpire,$sPath,$sDomain,$bSecure,$bHttpOnly);
    } else {
        if (!empty($sDomain)) {
            // Fix the domain to accept domains with and without 'www.'.
            if (strtolower(substr($sDomain, 0, 4)) == 'www.')  $sDomain = substr($sDomain, 4);
            $sDomain = '.' . $sDomain;

            // Remove port information.
            $Port = strpos($sDomain, ':');
            if ($Port !== false)  $sDomain = substr($sDomain, 0, $Port);
        }
        if (!$sValue) $sValue = 'deleted';
        header('Set-Cookie: ' . rawurlencode($sName) . '=' . rawurlencode($sValue)
                            . (empty($iExpire) ? '' : '; expires=' . gmdate('D, d-M-Y H:i:s', $iExpire) . ' GMT')
                            . (empty($sPath) ? '' : '; path=' . $sPath)
                            . (empty($sDomain) ? '' : '; domain=' . $sDomain)
                            . (!$bSecure ? '' : '; secure')
                            . (!$bHttpOnly ? '' : '; HttpOnly'), false);
    }
}

/**
 * session_regenerate_id replacement for PHP < 4.3.2
 *
 * This code is borrowed from Gallery, session.php version 1.53.2.1
 */
if (!function_exists('session_regenerate_id')) {
    function make_seed() {
        list($usec, $sec) = explode(' ', microtime());
        return (float)$sec + ((float)$usec * 100000);
    }

    function php_combined_lcg() {
        mt_srand(make_seed());
        $tv = gettimeofday();
        $lcg['s1'] = $tv['sec'] ^ (~$tv['usec']);
        $lcg['s2'] = mt_rand();
        $q = (int) ($lcg['s1'] / 53668);
        $lcg['s1'] = (int) (40014 * ($lcg['s1'] - 53668 * $q) - 12211 * $q);
        if ($lcg['s1'] < 0) {
            $lcg['s1'] += 2147483563;
        }
        $q = (int) ($lcg['s2'] / 52774);
        $lcg['s2'] = (int) (40692 * ($lcg['s2'] - 52774 * $q) - 3791 * $q);
        if ($lcg['s2'] < 0) {
            $lcg['s2'] += 2147483399;
        }
        $z = (int) ($lcg['s1'] - $lcg['s2']);
        if ($z < 1) {
            $z += 2147483562;
        }
        return $z * 4.656613e-10;
    }

    function session_regenerate_id() {
        global $base_uri;
        $tv = gettimeofday();
        sqgetGlobalVar('REMOTE_ADDR',$remote_addr,SQ_SERVER);
        $buf = sprintf("%.15s%ld%ld%0.8f", $remote_addr, $tv['sec'], $tv['usec'], php_combined_lcg() * 10);
        session_id(md5($buf));
        if (ini_get('session.use_cookies')) {
            // at a later stage we use sqsetcookie. At this point just do
            // what session_regenerate_id would do
            setcookie(session_name(), session_id(), NULL, $base_uri);
        }
        return TRUE;
    }
}


/**
 * php_self
 *
 * Creates an URL for the page calling this function, using either the PHP global
 * REQUEST_URI, or the PHP global PHP_SELF with QUERY_STRING added. Before 1.5.1
 * function was stored in function/strings.php.
 *
 * @return string the complete url for this page
 * @since 1.2.3
 */
function php_self () {
    if ( sqgetGlobalVar('REQUEST_URI', $req_uri, SQ_SERVER) && !empty($req_uri) ) {
      return $req_uri;
    }

    if ( sqgetGlobalVar('PHP_SELF', $php_self, SQ_SERVER) && !empty($php_self) ) {

      // need to add query string to end of PHP_SELF to match REQUEST_URI
      //
      if ( sqgetGlobalVar('QUERY_STRING', $query_string, SQ_SERVER) && !empty($query_string) ) {
         $php_self .= '?' . $query_string;
      }

      return $php_self;
    }

    return '';
}


/**
  * Find files and/or directories in a given directory optionally
  * limited to only those with the given file extension.  If the
  * directory is not found or cannot be opened, no error is generated;
  * only an empty file list is returned.
FIXME: do we WANT to throw an error or a notice or... or return FALSE?
  *
  * @param string $directory_path         The path (relative or absolute)
  *                                       to the desired directory.
  * @param mixed  $extension              The file extension filter - either
  *                                       an array of desired extension(s),
  *                                       or a comma-separated list of same
  *                                       (optional; default is to return 
  *                                       all files (dirs).
  * @param boolean $return_filenames_only When TRUE, only file/dir names
  *                                       are returned, otherwise the
  *                                       $directory_path string is
  *                                       prepended to each file/dir in
  *                                       the returned list (optional;
  *                                       default is filename/dirname only)
  * @param boolean $include_directories   When TRUE, directories are
  *                                       included (optional; default
  *                                       DO include directories).
  * @param boolean $directories_only      When TRUE, ONLY directories
  *                                       are included (optional; default
  *                                       is to include files too).
  * @param boolean $separate_files_and_directories When TRUE, files and
  *                                                directories are returned
  *                                                in separate lists, so
  *                                                the return value is
  *                                                formatted as a two-element
  *                                                array with the two keys
  *                                                "FILES" and "DIRECTORIES",
  *                                                where corresponding values
  *                                                are lists of either all
  *                                                files or all directories
  *                                                (optional; default do not
  *                                                split up return array).
  * @param boolean $only_sm               When TRUE, a security check will
  *                                       limit directory access to only
  *                                       paths within the SquirrelMail 
  *                                       installation currently being used
  *                                       (optional; default TRUE)
  *
  * @return array The requested file/directory list(s).
  *
  * @since 1.5.2
  *
  */
function list_files($directory_path, $extensions='', $return_filenames_only=TRUE,
                    $include_directories=TRUE, $directories_only=FALSE,
                    $separate_files_and_directories=FALSE, $only_sm=TRUE) {

    $files = array();
    $directories = array();


    // make sure requested path is under SM_PATH if needed
    //
    if ($only_sm) {
        if (strpos(realpath($directory_path), realpath(SM_PATH)) !== 0) {
            //plain_error_message(_("Illegal filesystem access was requested"));
            echo _("Illegal filesystem access was requested");
            exit;
        }
    }


    // validate given directory
    //
    if (empty($directory_path)
     || !is_dir($directory_path)
     || !($DIR = opendir($directory_path))) {
        return $files;
    }


    // ensure extensions is an array and is properly formatted 
    //
    if (!empty($extensions)) {
        if (!is_array($extensions))
            $extensions = explode(',', $extensions);
        $temp_extensions = array();
        foreach ($extensions as $ext)
            $temp_extensions[] = '.' . trim(trim($ext), '.');
        $extensions = $temp_extensions;
    } else $extensions = array();


    $directory_path = rtrim($directory_path, '/');


    // parse through the files
    //
    while (($file = readdir($DIR)) !== false) {

        if ($file == '.' || $file == '..') continue;

        if (!empty($extensions))
            foreach ($extensions as $ext)
                if (strrpos($file, $ext) !== (strlen($file) - strlen($ext)))
                    continue 2;

        // only use is_dir() if we really need to (be as efficient as possible)
        //
        $is_dir = FALSE;
        if (!$include_directories || $directories_only
                                  || $separate_files_and_directories) {
            if (is_dir($directory_path . '/' . $file)) {
                if (!$include_directories) continue;
                $is_dir = TRUE;
                $directories[] = ($return_filenames_only
                               ? $file
                               : $directory_path . '/' . $file);
            }
            if ($directories_only) continue;
        }

        if (!$separate_files_and_directories
         || ($separate_files_and_directories && !$is_dir)) {
            $files[] = ($return_filenames_only
                     ? $file
                     : $directory_path . '/' . $file);
        }

    }
    closedir($DIR);


    if ($directories_only) return $directories;
    if ($separate_files_and_directories) return array('FILES' => $files,
                                                      'DIRECTORIES' => $directories);
    return $files;

}


/**
 * Print variable
 *
 * sm_print_r($some_variable, [$some_other_variable [, ...]]);
 *
 * Debugging function - does the same as print_r, but makes sure special
 * characters are converted to htmlentities first.  This will allow
 * values like <some@email.address> to be displayed.
 * The output is wrapped in <<pre>> and <</pre>> tags.
 * Since 1.4.2 accepts unlimited number of arguments.
 * @since 1.4.1
 * @return void
 */
function sm_print_r() {
    ob_start();  // Buffer output
    foreach(func_get_args() as $var) {
        print_r($var);
        echo "\n";
        // php has get_class_methods function that can print class methods
        if (is_object($var)) {
            // get class methods if $var is object
            $aMethods=get_class_methods(get_class($var));
            // make sure that $aMethods is array and array is not empty
            if (is_array($aMethods) && $aMethods!=array()) {
                echo "Object methods:\n";
                foreach($aMethods as $method) {
                    echo '* ' . $method . "\n";
                }
            }
            echo "\n";
        }
    }
    $buffer = ob_get_contents(); // Grab the print_r output
    ob_end_clean();  // Silently discard the output & stop buffering
    print '<div align="left"><pre>';
    print htmlentities($buffer);
    print '</pre></div>';
}


/**
  * Sanitize a value using htmlspecialchars() or similar, but also
  * recursively run htmlspecialchars() (or similar) on array keys
  * and values.
  *
  * If $value is not a string or an array with strings in it,
  * the value is returned as is.
  *
  * @param mixed $value       The value to be sanitized.
  * @param mixed $quote_style Either boolean or an integer.  If it
  *                           is an integer, it must be the PHP
  *                           constant indicating if/how to escape
  *                           quotes: ENT_QUOTES, ENT_COMPAT, or
  *                           ENT_NOQUOTES.  If it is a boolean value,
  *                           it must be TRUE and thus indicates
  *                           that the only sanitizing to be done
  *                           herein is to replace single and double
  *                           quotes with &#039; and &quot;, no other
  *                           changes are made to $value.  If it is
  *                           boolean and FALSE, behavior reverts
  *                           to same as if the value was ENT_QUOTES
  *                           (OPTIONAL; default is ENT_QUOTES).
  *
  * @return mixed The sanitized value.
  *
  * @since 1.5.2
  *
  **/
function sq_htmlspecialchars($value, $quote_style=ENT_QUOTES) {

    if ($quote_style === FALSE) $quote_style = ENT_QUOTES;

    // array?  go recursive...
    //
    if (is_array($value)) {
        $return_array = array();
        foreach ($value as $key => $val) {
            $return_array[sq_htmlspecialchars($key, $quote_style)]
                = sq_htmlspecialchars($val, $quote_style);
        }
        return $return_array;

    // sanitize strings only
    //
    } else if (is_string($value)) {
        if ($quote_style === TRUE)
            return str_replace(array('\'', '"'), array('&#039;', '&quot;'), $value);
        else
            return htmlspecialchars($value, $quote_style);
    }

    // anything else gets returned with no changes
    //
    return $value;

}