Set more restrictive permissions on abook files - matches how pref files are treated...
[squirrelmail.git] / functions / abook_local_file.php
index 7863fa7c1b62991639842cf1064fe9c3aba708a0..fc05257a4231685866cbc4b3d66dfeb730859381 100644 (file)
 /**
  * abook_local_file.php
  *
- * Copyright (c) 1999-2001 The Squirrelmail Development Team
- * Licensed under the GNU GPL. For full terms see the file COPYING.
+ * @copyright © 1999-2007 The SquirrelMail Project Team
+ * @license http://opensource.org/licenses/gpl-license.php GNU Public License
+ * @version $Id$
+ * @package squirrelmail
+ * @subpackage addressbook
+ */
+
+/**
+ * Backend for address book as a pipe separated file
  *
- * Backend for addressbook as a pipe separated file
+ * Stores the address book in a local file
  *
  * An array with the following elements must be passed to
  * the class constructor (elements marked ? are optional):
- *
- *    filename  => path to addressbook file
- *  ? create    => if true: file is created if it does not exist.
- *  ? umask     => umask set before opening file.
- *
+ *<pre>
+ *   filename  => path to addressbook file
+ * ? create    => if true: file is created if it does not exist.
+ * ? umask     => umask set before opening file.
+ * ? name      => name of address book.
+ * ? detect_writeable => detect address book access permissions by
+ *                checking file permissions.
+ * ? writeable => allow writing into address book. Used only when
+ *                detect_writeable is set to false.
+ * ? listing   => enable/disable listing
+ *</pre>
  * NOTE. This class should not be used directly. Use the
  *       "AddressBook" class instead.
- *
- * $Id$
+ * @package squirrelmail
  */
-
-/*****************************************************************/
-/*** THIS FILE NEEDS TO HAVE ITS FORMATTING FIXED!!!           ***/
-/*** PLEASE DO SO AND REMOVE THIS COMMENT SECTION.             ***/
-/***    + Base level indent should begin at left margin, as    ***/
-/***      the first line of the class definition below.        ***/
-/***    + All identation should consist of four space blocks   ***/
-/***    + Tab characters are evil.                             ***/
-/***    + all comments should use "slash-star ... star-slash"  ***/
-/***      style -- no pound characters, no slash-slash style   ***/
-/***    + FLOW CONTROL STATEMENTS (if, while, etc) SHOULD      ***/
-/***      ALWAYS USE { AND } CHARACTERS!!!                     ***/
-/***    + Please use ' instead of ", when possible. Note "     ***/
-/***      should always be used in _( ) function calls.        ***/
-/*** Thank you for your help making the SM code more readable. ***/
-/*****************************************************************/
-
 class abook_local_file extends addressbook_backend {
-     var $btype = 'local';
-     var $bname = 'local_file';
-
-     var $filename   = '';
-     var $filehandle = 0;
-     var $create     = false;
-     var $umask;
-
-     // ========================== Private =======================
-
-     // Constructor
-     function abook_local_file($param) {
-       $this->sname = _("Personal address book");
-       $this->umask = Umask();
-
-       if(is_array($param)) {
-        if(empty($param['filename']))
-          return $this->set_error('Invalid parameters');
-        if(!is_string($param['filename']))
-          return $this->set_error($param['filename'] . ': '.
-                                  _("Not a file name"));
-
-        $this->filename = $param['filename'];
-
-        if($param['create'])
-          $this->create = true;
-        if(isset($param['umask'])) 
-          $this->umask = $param['umask'];
-
-        if(!empty($param['name']))
-          $this->sname = $param['name'];
-
-        $this->open(true);
-       } else {
-        $this->set_error('Invalid argument to constructor');
-       }
-     }
-
-     // Open the addressbook file and store the file pointer.
-     // Use $file as the file to open, or the class' own 
-     // filename property. If $param is empty and file is  
-     // open, do nothing.
-     function open($new = false) {
-       $this->error = '';
-       $file   = $this->filename;
-       $create = $this->create;
-
-       // Return true is file is open and $new is unset
-       if($this->filehandle && !$new)
-        return true;
-
-       // Check that new file exitsts
-       if((!(file_exists($file) && is_readable($file))) && !$create)
-        return $this->set_error("$file: " . _("No such file or directory"));
-
-       // Close old file, if any
-       if($this->filehandle) $this->close();
-       
-       // Open file. First try to open for reading and writing,
-       // but fall back to read only.
-       umask($this->umask);
-       $fh = @fopen($file, 'a+');
-       if($fh) {
-        $this->filehandle = &$fh;
-        $this->filename   = $file;
-        $this->writeable  = true;
-       } else {
-        $fh = @fopen($file, 'r');
-        if($fh) {
-          $this->filehandle = &$fh;
-          $this->filename   = $file;
-          $this->writeable  = false;
-        } else {
-          return $this->set_error("$file: " . _("Open failed"));
-        }
-       }
-
-       return true;
-     }
-
-     // Close the file and forget the filehandle
-     function close() {
-       @fclose($this->filehandle);
-       $this->filehandle = 0;
-       $this->filename   = '';
-       $this->writable   = false;
-     }
-
-     // Lock the datafile - try 20 times in 5 seconds
-     function lock() {
-       for($i = 0 ; $i < 20 ; $i++) {
-        if(flock($this->filehandle, 2 + 4)) 
-          return true;
-        else
-          usleep(250000);
-       }
-       return false;
-     }
-
-     // Lock the datafile
-     function unlock() {
-       return flock($this->filehandle, 3);
-     }
-
-     // Overwrite the file with data from $rows
-     // NOTE! Previous locks are broken by this function
-     function overwrite(&$rows) {
-       $newfh = @fopen($this->filename, 'w');
-       if(!$newfh)
-        return $this->set_error("$file: " . _("Open failed"));
-
-       for($i = 0 ; $i < sizeof($rows) ; $i++) {
-        if(is_array($rows[$i]))
-          fwrite($newfh, join('|', $rows[$i]) . "\n");
-       }       
-
-       fclose($newfh);
-       $this->unlock();
-       $this->open(true);
-       return true;
-     }
-     
-     // ========================== Public ========================
-     
-     // Search the file
-     function search($expr) {
-
-       // To be replaced by advanded search expression parsing
-       if(is_array($expr)) return;
-
-       // Make regexp from glob'ed expression
-       // May want to quote other special characters like (, ), -, [, ], etc.
-       $expr = str_replace('?', '.', $expr);
-       $expr = str_replace('*', '.*', $expr);
-
-       $res = array();
-       if(!$this->open())
-        return false;
-
-       @rewind($this->filehandle);
-       
-       while ($row = @fgetcsv($this->filehandle, 2048, '|')) {
-        $line = join(' ', $row);
-        if(eregi($expr, $line)) {
-          array_push($res, array('nickname'  => $row[0],
-                                 'name'      => $row[1] . ' ' . $row[2],
-                                 'firstname' => $row[1],
-                                 'lastname'  => $row[2],
-                                 'email'     => $row[3],
-                                 'label'     => $row[4],
-                                 'backend'   => $this->bnum,
-                                 'source'    => &$this->sname));
-        }
-       }
-       
-       return $res;
-     }
-     
-     // Lookup alias
-     function lookup($alias) {
-       if(empty($alias))
-        return array();
-
-       $alias = strtolower($alias);
-       
-       $this->open();
-       @rewind($this->filehandle);
-       
-       while ($row = @fgetcsv($this->filehandle, 2048, '|')) {
-        if(strtolower($row[0]) == $alias) {
-          return array('nickname'  => $row[0],
-                       'name'      => $row[1] . ' ' . $row[2],
-                       'firstname' => $row[1],
-                       'lastname'  => $row[2],
-                       'email'     => $row[3],
-                       'label'     => $row[4],
-                       'backend'   => $this->bnum,
-                       'source'    => &$this->sname);
-        }
-       }
-       
-       return array();
-     }
-
-     // List all addresses
-     function list_addr() {
-       $res = array();
-       $this->open();
-       @rewind($this->filehandle);
-       
-       while ($row = @fgetcsv($this->filehandle, 2048, '|')) {
-        array_push($res, array('nickname'  => $row[0],
-                               'name'      => $row[1] . ' ' . $row[2],
-                               'firstname' => $row[1],
-                               'lastname'  => $row[2],
-                               'email'     => $row[3],
-                               'label'     => $row[4],
-                               'backend'   => $this->bnum,
-                               'source'    => &$this->sname));
-       }
-       return $res;
-     }
-
-     // Add address
-     function add($userdata) {
-       if(!$this->writeable) 
-        return $this->set_error(_("Addressbook is read-only"));
-
-       // See if user exist already
-       $ret = $this->lookup($userdata['nickname']);
-       if(!empty($ret))
-        return $this->set_error(sprintf(_("User '%s' already exist"),
-                                        $ret['nickname']));
-
-       // Here is the data to write
-       $data = $userdata['nickname'] . '|' . $userdata['firstname'] . '|' .
-               $userdata['lastname'] . '|' . $userdata['email'] . '|' .
-               $userdata['label'];
-       // Strip linefeeds
-       $data = ereg_replace("[\r\n]", ' ', $data);
-       // Add linefeed at end
-       $data = $data . "\n";
-
-       // Reopen file, just to be sure
-       $this->open(true);
-       if(!$this->writeable) 
-        return $this->set_error(_("Addressbook is read-only"));
-
-       // Lock the file
-       if(!$this->lock())
-        return $this->set_error(_("Could not lock datafile"));
-
-       // Write
-       $r = fwrite($this->filehandle, $data);
-
-       // Unlock file
-       $this->unlock();
-
-       // Test write result and exit if OK
-       if($r > 0) return true;
-
-       // Fail
-       $this->set_error(_("Write to addressbook failed"));
-       return false;
-     }
-
-     // Delete address
-     function remove($alias) {
-       if(!$this->writeable) 
-        return $this->set_error(_("Addressbook is read-only"));
-
-       // Lock the file to make sure we're the only process working
-       // on it.
-       if(!$this->lock())
-        return $this->set_error(_("Could not lock datafile"));
-
-       // Read file into memory, ignoring nicknames to delete
-       @rewind($this->filehandle);
-       $i = 0;
-       $rows = array();
-       while($row = @fgetcsv($this->filehandle, 2048, '|')) {
-        if(!in_array($row[0], $alias))
-          $rows[$i++] = $row;
-       }
-
-       // Write data back
-       if(!$this->overwrite($rows)) {
-        $this->unlock();
-        return false;
-       }
-
-       $this->unlock();
-       return true;
-     }
-
-     // Modify address
-     function modify($alias, $userdata) {
-       if(!$this->writeable) 
-        return $this->set_error(_("Addressbook is read-only"));
-
-       // See if user exist
-       $ret = $this->lookup($alias);
-       if(empty($ret))
-        return $this->set_error(sprintf(_("User '%s' does not exist"),
-                                        $alias));
-
-       // Lock the file to make sure we're the only process working
-       // on it.
-       if(!$this->lock())
-        return $this->set_error(_("Could not lock datafile"));
-
-       // Read file into memory, modifying the data for the 
-       // user identifyed by $alias
-       $this->open(true);
-       @rewind($this->filehandle);
-       $i = 0;
-       $rows = array();
-       while($row = @fgetcsv($this->filehandle, 2048, '|')) {
-        if(strtolower($row[0]) != strtolower($alias)) {
-          $rows[$i++] = $row;
-        } else {
-          $rows[$i++] = array(0 => $userdata['nickname'],
-                              1 => $userdata['firstname'],
-                              2 => $userdata['lastname'],
-                              3 => $userdata['email'], 
-                              4 => $userdata['label']);
-        }
-       }
-
-       // Write data back
-       if(!$this->overwrite($rows)) {
-        $this->unlock();
-        return false;
-       }
-
-       $this->unlock();
-       return true;
-     }
-     
-   } // End of class abook_local_file
-?>
+    /**
+     * Backend type
+     * @var string
+     */
+    var $btype = 'local';
+    /**
+     * Backend name
+     * @var string
+     */
+    var $bname = 'local_file';
+
+    /**
+     * File used to store data
+     * @var string
+     */
+    var $filename = '';
+    /**
+     * File handle
+     * @var object
+     */
+    var $filehandle = 0;
+    /**
+     * Create file, if it not present
+     * @var bool
+     */
+    var $create = false;
+    /**
+     * Detect, if address book is writeable by checking file permisions
+     * @var bool
+     */
+    var $detect_writeable   = true;
+    /**
+     * Control write access to address book
+     *
+     * Option does not have any effect, if 'detect_writeable' is 'true'
+     * @var bool
+     */
+    var $writeable = false;
+    /**
+     * controls listing of address book
+     * @var bool
+     */
+    var $listing = true;
+    /**
+     * Umask of the file
+     * @var string
+     */
+    var $umask;
+    /**
+     * Sets max entry size (number of bytes used for all address book fields 
+     * (including escapes) + 4 delimiters + 1 linefeed)
+     * @var integer
+     * @since 1.5.2
+     */
+    var $line_length = 2048;
+
+    /* ========================== Private ======================= */
+
+    /**
+     * Constructor
+     * @param array $param backend options
+     * @return bool
+     */
+    function abook_local_file($param) {
+        $this->sname = _("Personal Address Book");
+        $this->umask = Umask();
+
+        if(is_array($param)) {
+            if(empty($param['filename'])) {
+                return $this->set_error('Invalid parameters');
+            }
+            if(!is_string($param['filename'])) {
+                return $this->set_error($param['filename'] . ': '.
+                     _("Not a file name"));
+            }
+
+            $this->filename = $param['filename'];
+
+            if(isset($param['create'])) {
+                $this->create = $param['create'];
+            }
+            if(isset($param['umask'])) {
+                $this->umask = $param['umask'];
+            }
+            if(isset($param['name'])) {
+                $this->sname = $param['name'];
+            }
+            if(isset($param['detect_writeable'])) {
+                $this->detect_writeable = $param['detect_writeable'];
+            }
+            if(!empty($param['writeable'])) {
+                $this->writeable = $param['writeable'];
+            }
+            if(isset($param['listing'])) {
+                $this->listing = $param['listing'];
+            }
+            if(isset($param['line_length']) && ! empty($param['line_length'])) {
+                $this->line_length = (int) $param['line_length'];
+            }
+
+            $this->open(true);
+        } else {
+            $this->set_error('Invalid argument to constructor');
+        }
+    }
+
+    /**
+     * Open the addressbook file and store the file pointer.
+     * Use $file as the file to open, or the class' own
+     * filename property. If $param is empty and file is
+     * open, do nothing.
+     * @param bool $new is file already opened
+     * @return bool
+     */
+    function open($new = false) {
+        $this->error = '';
+        $file   = $this->filename;
+        $create = $this->create;
+        $fopenmode = (($this->writeable && sq_is_writable($file)) ? 'a+' : 'r');
+
+        /* Return true is file is open and $new is unset */
+        if($this->filehandle && !$new) {
+            return true;
+        }
+
+        /* Check that new file exitsts */
+        if((!(file_exists($file) && is_readable($file))) && !$create) {
+            return $this->set_error("$file: " . _("No such file or directory"));
+        }
+
+        /* Close old file, if any */
+        if($this->filehandle) { $this->close(); }
+
+        umask($this->umask);
+        if (! $this->detect_writeable) {
+            $fh = @fopen($file,$fopenmode);
+            if ($fh) {
+                $this->filehandle = &$fh;
+                $this->filename = $file;
+            } else {
+                return $this->set_error("$file: " . _("Open failed"));
+            }
+        } else {
+            /* Open file. First try to open for reading and writing,
+             * but fall back to read only. */
+            $fh = @fopen($file, 'a+');
+            if($fh) {
+                $this->filehandle = &$fh;
+                $this->filename   = $file;
+                $this->writeable  = true;
+            } else {
+                $fh = @fopen($file, 'r');
+                if($fh) {
+                    $this->filehandle = &$fh;
+                    $this->filename   = $file;
+                    $this->writeable  = false;
+                } else {
+                    return $this->set_error("$file: " . _("Open failed"));
+                }
+            }
+        }
+        return true;
+    }
+
+    /** Close the file and forget the filehandle */
+    function close() {
+        @fclose($this->filehandle);
+        $this->filehandle = 0;
+        $this->filename   = '';
+        $this->writable   = false;
+    }
+
+    /** Lock the datafile - try 20 times in 5 seconds */
+    function lock() {
+        for($i = 0 ; $i < 20 ; $i++) {
+            if(flock($this->filehandle, 2 + 4))
+                return true;
+            else
+                usleep(250000);
+        }
+        return false;
+    }
+
+    /** Unlock the datafile */
+    function unlock() {
+        return flock($this->filehandle, 3);
+    }
+
+    /**
+     * Overwrite the file with data from $rows
+     * NOTE! Previous locks are broken by this function
+     * @param array $rows new data
+     * @return bool
+     */
+    function overwrite(&$rows) {
+        $this->unlock();
+        $newfh = @fopen($this->filename.'.tmp', 'w');
+
+        if(!$newfh) {
+            return $this->set_error($this->filename. '.tmp:' . _("Open failed"));
+        }
+
+        for($i = 0, $cnt=sizeof($rows) ; $i < $cnt ; $i++) {
+            if(is_array($rows[$i])) {
+                for($j = 0, $cnt_part=count($rows[$i]) ; $j < $cnt_part ; $j++) {
+                    $rows[$i][$j] = $this->quotevalue($rows[$i][$j]);
+                }
+                $tmpwrite = sq_fwrite($newfh, join('|', $rows[$i]) . "\n");
+                if ($tmpwrite === FALSE) {
+                    return $this->set_error($this->filename . '.tmp:' . _("Write failed"));
+                }
+            }
+        }
+
+        fclose($newfh);
+        if (!@copy($this->filename . '.tmp' , $this->filename)) {
+          return $this->set_error($this->filename . ':' . _("Unable to update"));
+        }
+        @unlink($this->filename . '.tmp');
+        @chmod($this->filename, 0600);
+        $this->unlock();
+        $this->open(true);
+        return true;
+    }
+
+    /* ========================== Public ======================== */
+
+    /**
+     * Search the file
+     * @param string $expr search expression
+     * @return array search results
+     */
+    function search($expr) {
+
+        /* To be replaced by advanded search expression parsing */
+        if(is_array($expr)) { return; }
+
+        // don't allow wide search when listing is disabled.
+        if ($expr=='*' && ! $this->listing)
+            return array();
+
+        /* Make regexp from glob'ed expression
+         * May want to quote other special characters like (, ), -, [, ], etc. */
+        $expr = str_replace('?', '.', $expr);
+        $expr = str_replace('*', '.*', $expr);
+
+        $res = array();
+        if(!$this->open()) {
+            return false;
+        }
+        @rewind($this->filehandle);
+
+        while ($row = @fgetcsv($this->filehandle, $this->line_length, '|')) {
+            if (count($row)<5) {
+                /**
+                 * address book is corrupted.
+                 */
+                global $oTemplate;
+                error_box(_("Address book is corrupted. Required fields are missing."));
+                $oTemplate->display('footer.tpl');
+                die();
+            } else {
+                $line = join(' ', $row);
+                /**
+                 * TODO: regexp search is supported only in local_file backend.
+                 * Do we check format of regexp or ignore errors?
+                 */
+                // errors on eregi call are suppressed in order to prevent display of regexp compilation errors
+                if(@eregi($expr, $line)) {
+                    array_push($res, array('nickname'  => $row[0],
+                        'name'      => $this->fullname($row[1], $row[2]),
+                        'firstname' => $row[1],
+                        'lastname'  => $row[2],
+                        'email'     => $row[3],
+                        'label'     => $row[4],
+                        'backend'   => $this->bnum,
+                        'source'    => &$this->sname));
+                }
+            }
+        }
+
+        return $res;
+    }
+
+    /**
+     * Lookup an address by the indicated field.
+     *
+     * @param string  $value The value to look up
+     * @param integer $field The field to look in, should be one
+     *                       of the SM_ABOOK_FIELD_* constants
+     *                       defined in include/constants.php
+     *                       (OPTIONAL; defaults to nickname field)
+     *                       NOTE: uniqueness is only guaranteed
+     *                       when the nickname field is used here;
+     *                       otherwise, the first matching address
+     *                       is returned.
+     *
+     * @return array Array with lookup results when the value
+     *               was found, an empty array if the value was
+     *               not found.
+     *
+     */
+    function lookup($value, $field=SM_ABOOK_FIELD_NICKNAME) {
+        if(empty($value)) {
+            return array();
+        }
+
+        $value = strtolower($value);
+
+        $this->open();
+        @rewind($this->filehandle);
+
+        while ($row = @fgetcsv($this->filehandle, $this->line_length, '|')) {
+            if (count($row)<5) {
+                /**
+                 * address book is corrupted.
+                 */
+                global $oTemplate;
+                error_box(_("Address book is corrupted. Required fields are missing."));
+                $oTemplate->display('footer.tpl');
+                die();
+            } else {
+                if(strtolower($row[$field]) == $value) {
+                   return array('nickname'  => $row[0],
+                      'name'      => $this->fullname($row[1], $row[2]),
+                      'firstname' => $row[1],
+                      'lastname'  => $row[2],
+                      'email'     => $row[3],
+                      'label'     => $row[4],
+                      'backend'   => $this->bnum,
+                      'source'    => &$this->sname);
+                }
+            }
+        }
+
+        return array();
+    }
+
+    /**
+     * List all addresses
+     * @return array list of all addresses
+     */
+    function list_addr() {
+        $res = array();
+
+        if(isset($this->listing) && !$this->listing) {
+            return array();
+        }
+
+        $this->open();
+        @rewind($this->filehandle);
+
+        while ($row = @fgetcsv($this->filehandle, $this->line_length, '|')) {
+            if (count($row)<5) {
+                /**
+                 * address book is corrupted. Don't be nice to people that 
+                 * violate address book formating.
+                 */
+                global $oTemplate;
+                error_box(_("Address book is corrupted. Required fields are missing."));
+                $oTemplate->display('footer.tpl');
+                die();
+            } else {
+                array_push($res, array('nickname'  => $row[0],
+                    'name'      => $this->fullname($row[1], $row[2]),
+                    'firstname' => $row[1],
+                    'lastname'  => $row[2],
+                    'email'     => $row[3],
+                    'label'     => $row[4],
+                    'backend'   => $this->bnum,
+                    'source'    => &$this->sname));
+            }
+        }
+        return $res;
+    }
+
+    /**
+     * Add address
+     * @param array $userdata new data
+     * @return bool
+     */
+    function add($userdata) {
+        if(!$this->writeable) {
+            return $this->set_error(_("Address book is read-only"));
+        }
+        /* See if user exists already */
+        $ret = $this->lookup($userdata['nickname']);
+        if(!empty($ret)) {
+            // i18n: don't use html formating in translation
+            return $this->set_error(sprintf(_("User \"%s\" already exists"),$ret['nickname']));
+        }
+
+        /* Here is the data to write */
+        $data = $this->quotevalue($userdata['nickname']) . '|' .
+                $this->quotevalue($userdata['firstname']) . '|' .
+                $this->quotevalue((!empty($userdata['lastname'])?$userdata['lastname']:'')) . '|' .
+                $this->quotevalue($userdata['email']) . '|' .
+                $this->quotevalue((!empty($userdata['label'])?$userdata['label']:''));
+
+        /* Strip linefeeds */
+        $data = ereg_replace("[\r\n]", ' ', $data);
+
+        /**
+         * Make sure that entry fits into allocated record space.
+         * One byte is reserved for linefeed
+         */
+        if (strlen($data) >= $this->line_length) {
+            return $this->set_error(_("Address book entry is too big"));
+        }
+
+        /* Add linefeed at end */
+        $data = $data . "\n";
+
+        /* Reopen file, just to be sure */
+        $this->open(true);
+        if(!$this->writeable) {
+            return $this->set_error(_("Address book is read-only"));
+        }
+
+        /* Lock the file */
+        if(!$this->lock()) {
+            return $this->set_error(_("Could not lock datafile"));
+        }
+
+        /* Write */
+        $r = sq_fwrite($this->filehandle, $data);
+
+        /* Unlock file */
+        $this->unlock();
+
+        /* Test write result */
+        if($r === FALSE) {
+            /* Fail */
+            $this->set_error(_("Write to address book failed"));
+            return FALSE;
+        }
+
+        return TRUE;
+    }
+
+    /**
+     * Delete address
+     * @param string $alias alias that has to be deleted
+     * @return bool
+     */
+    function remove($alias) {
+        if(!$this->writeable) {
+            return $this->set_error(_("Address book is read-only"));
+        }
+
+        /* Lock the file to make sure we're the only process working
+         * on it. */
+        if(!$this->lock()) {
+            return $this->set_error(_("Could not lock datafile"));
+        }
+
+        /* Read file into memory, ignoring nicknames to delete */
+        @rewind($this->filehandle);
+        $i = 0;
+        $rows = array();
+        while($row = @fgetcsv($this->filehandle, $this->line_length, '|')) {
+            if(!in_array($row[0], $alias)) {
+                $rows[$i++] = $row;
+            }
+        }
+
+        /* Write data back */
+        if(!$this->overwrite($rows)) {
+            $this->unlock();
+            return false;
+        }
+
+        $this->unlock();
+        return true;
+    }
+
+    /**
+     * Modify address
+     * @param string $alias modified alias
+     * @param array $userdata new data
+     * @return bool true, if operation successful
+     */
+    function modify($alias, $userdata) {
+        if(!$this->writeable) {
+            return $this->set_error(_("Address book is read-only"));
+        }
+
+        /* See if user exists */
+        $ret = $this->lookup($alias);
+        if(empty($ret)) {
+            // i18n: don't use html formating in translation
+            return $this->set_error(sprintf(_("User \"%s\" does not exist"),$alias));
+        }
+        
+        /* If the alias changed, see if the new alias exists */
+        if (strtolower($alias) != strtolower($userdata['nickname'])) {
+            $ret = $this->lookup($userdata['nickname']);
+            if (!empty($ret)) {
+                return $this->set_error(sprintf(_("User \"%s\" already exists"), $userdata['nickname']));
+            }
+        }
+        
+        /* Lock the file to make sure we're the only process working
+         * on it. */
+        if(!$this->lock()) {
+            return $this->set_error(_("Could not lock datafile"));
+        }
+
+        /* calculate userdata size */
+        $data = $this->quotevalue($userdata['nickname']) . '|'
+            . $this->quotevalue($userdata['firstname']) . '|'
+            . $this->quotevalue((!empty($userdata['lastname'])?$userdata['lastname']:'')) . '|'
+            . $this->quotevalue($userdata['email']) . '|'
+            . $this->quotevalue((!empty($userdata['label'])?$userdata['label']:''));
+        /* make sure that it fits into allocated space */
+        if (strlen($data) >= $this->line_length) {
+            return $this->set_error(_("Address book entry is too big"));
+        }
+        
+        /* Read file into memory, modifying the data for the
+         * user identified by $alias */
+        $this->open(true);
+        @rewind($this->filehandle);
+        $i = 0;
+        $rows = array();
+        while($row = @fgetcsv($this->filehandle, $this->line_length, '|')) {
+            if(strtolower($row[0]) != strtolower($alias)) {
+                $rows[$i++] = $row;
+            } else {
+                $rows[$i++] = array(0 => $userdata['nickname'],
+                                    1 => $userdata['firstname'],
+                                    2 => (!empty($userdata['lastname'])?$userdata['lastname']:''),
+                                    3 => $userdata['email'],
+                                    4 => (!empty($userdata['label'])?$userdata['label']:''));
+            }
+        }
+
+        /* Write data back */
+        if(!$this->overwrite($rows)) {
+            $this->unlock();
+            return false;
+        }
+
+        $this->unlock();
+        return true;
+    }
+
+    /**
+     * Function for quoting values before saving
+     * @param string $value string that has to be quoted
+     * @param string quoted string
+     */
+    function quotevalue($value) {
+        /* Quote the field if it contains | or ". Double quotes need to
+         * be replaced with "" */
+        if(ereg("[|\"]", $value)) {
+            $value = '"' . str_replace('"', '""', $value) . '"';
+        }
+        return $value;
+    }
+}