Source for file File.php

<?php
require_once('Driver.php');
require_once('System/SharedMemory.php');
 
/**
 * A driver that use plain filesystem as data store
 */
class AJAX_Locking_Driver_File extends AJAX_Locking_Driver
{
    var $dir;
 
    /**
     * Constructor
     *
     * @return AJAX_Locking_Driver 
     */
    function AJAX_Locking_Driver_File($dir = '/tmp', $timeout = false)
    {
        parent::AJAX_Locking_Driver($timeout);
 
        $this->dir = realpath($dir);
    }
 
    /**
     * Locks an object
     *
     * @param mixed $user    id of the user who wants to lock
     * @param string $type    type/classname of the object
     * @param mixed $id        id of the object
     * @return boolean true if the unlock was successfull, false otherwise
     */
    function lock($user, $type, $id)
    {
        $key = $this->_getKey($type, $id);
 
        $value = $this->_get($key);
        if (empty($value)) {
            // object is unlocked: lock it
            $value = $this->_getValue($user, $type, $id);
            $this->_set($key, $value);
            return true;
        } else {
            // object is locked: check if lock expired
            list($owner, $type, $id, $time) = $this->_parseValue($value);
            if (time() - $time > $this->timeout) {
                // lock expired: remove it and lock
                $this->_rm($key);
                $this->_set($key, $value);
                return true;
            } else {
                // object properly locked by (another?) user
                return ($owner == $user);
            }
        }
 
    }
 
    /**
     * Unlocks an object
     *
     * @param mixed $user    id of the user who wants to unlock
     * @param string $type    type/classname of the object
     * @param mixed $id        id of the object
     * @return boolean true if the unlock was successfull, false otherwise
     */
    function unlock($user, $type, $id)
    {
        $key = $this->_getKey($type, $id);
        $value = $this->_get($key);
        if (empty($value)) {
            // object was not locked
            return false;
        } else {
            // check if user is owner of the lock
            list($owner, $type, $id, $time) = $this->_parseValue($value);
            if ($user == $owner) {
                // unlock it
                $this->_rm($key);
                return true;
            } else {
                // user cannot unlock it
                return false;
            }
        }
    }
 
    /**
     * Returns the status of the object (lock or unlocked)
     *
     * @param mixed $user    id of the user who wants to know the object's status
     * @param string $type    type/classname of the object
     * @param mixed $id        id of the object
     * @return string the status and the owner of the object
     */
    function status($user, $type, $id)
    {
        $key = $this->_getKey($type, $id);
        $value = $this->_get($key);
        if (empty($value)) {
            // object is unlocked
            return AJAX_LOCKING_UNLOCKED . '~' . 'noboby';
        } else {
            // object is locked:
            // 1. check if current user is owner of the lock
            // 2. check if lock expired
            list($owner, $type, $id, $time) = $this->_parseValue($value);
            $timeout = (time() - $time > $this->timeout);
            if ($owner == $user) {
                if ($timeout) {
                    // lock expired: remove it and inform it's ower
                    $this->_rm($key);
                    return AJAX_LOCKING_TIMEOUT . '~' . $owner;
                } else {
                    return AJAX_LOCKING_OWNED . '~' . $owner;
                }
            } else {
                if ($timeout) {
                    // lock expired: remove it
                    $this->_rm($key);
                    return AJAX_LOCKING_UNLOCKED . '~' . 'nobody';
                } else {
                    return AJAX_LOCKING_LOCKED . '~' . $owner;
                }
            }
        }
    }
 
    /**
     * Returns the list of all active locks for administration purpose
     *
     * @return array of locks (owner, type, id), false if not implemented
     */
    function getLocks()
    {
        $files = array();
        $dh  = opendir($this->dir);
        while (false !== ($filename = readdir($dh))) {
            if (strstr($filename, AJAX_LOCKING_PREFIX) == $filename) {
                $files[] = $filename;
            }
        }
 
        $locks = array();
        foreach ($files as $f) {
            $value = file_get_contents($this->dir . DIRECTORY_SEPARATOR . $f);
            if ($value) {
                list($owner, $type, $id, $time) = $this->_parseValue($value);
                $timeout = (time() - $time > $this->timeout);
                if (!$timeout) {
                    $locks[] = array(
                        'owner' => $owner,
                        'type' => $type,
                        'id' => $id
                    );
                }
            }
        }
 
        return $locks;
    }
 
    /**
     * Administrately delete lock
     *
     * @param string $type 
     * @param mixed $id 
     *
     * @return true if the lock is deleted successfully, false otherwise
     */
    function delete($type, $id)
    {
        $key = $this->_getKey($type, $id);
        $this->_rm($key);
    }
 
 
    /**
     * Returns the values stored in file $key
     *
     * @param string $key 
     * @return string 
     */
    function _get($key)
    {
        $value = '';
        $filename = $this->dir . DIRECTORY_SEPARATOR . $key;
        if (file_exists($filename)) {
            $value = file_get_contents($filename);
        }
        return $value;
    }
 
    /**
     * Puts the value $value into file $key
     *
     * @param string $key 
     * @param string $value 
     */
    function _set($key, $value)
    {
        $filename = $this->dir . DIRECTORY_SEPARATOR . $key;
        $fp = fopen($filename, 'w');
        fwrite($fp, $value);
        fclose($fp);
    }
 
    /**
     * Remove the file $key
     *
     * @param string $key 
     */
    function _rm($key)
    {
        $filename = $this->dir . DIRECTORY_SEPARATOR . $key;
        return @unlink($filename);
    }
 
}
?>