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124 lines
2.2 KiB
PHP
124 lines
2.2 KiB
PHP
<?php
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/**
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*
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* @package phpBB3
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* @copyright (c) 2012 phpBB Group
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* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
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*
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*/
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/**
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* @ignore
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*/
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if (!defined('IN_PHPBB'))
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{
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exit;
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}
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/**
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* File locking class
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* @package phpBB3
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*/
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class phpbb_lock_flock
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{
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/**
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* Path to the file access to which is controlled
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*
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* @var string
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*/
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private $path;
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/**
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* File pointer for the lock file
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* @var string
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*/
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private $lock_fp;
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/**
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* Creates an instance of the lock.
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*
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* You have to call acquire() to actually create the lock.
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*
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* @param string $path Path to the file access to which is controlled
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*/
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public function __construct($path)
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{
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$this->path = $path;
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$this->lock_fp = null;
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}
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/**
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* Tries to acquire the lock.
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*
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* As a lock may only be held by one process at a time, lock
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* acquisition may fail if another process is holding the lock.
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*
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* @return bool true if lock was acquired
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* false otherwise
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*/
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public function acquire()
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{
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if ($this->locked)
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{
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return false;
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}
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// For systems that can't have two processes opening
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// one file for writing simultaneously
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if (file_exists($this->path . '.lock'))
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{
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$mode = 'rb';
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}
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else
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{
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$mode = 'wb';
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}
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$this->lock_fp = @fopen($this->path . '.lock', $mode);
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if ($mode == 'wb')
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{
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if (!$this->lock_fp)
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{
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// Two processes may attempt to create lock file at the same time.
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// Have the losing process try opening the lock file again for reading
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// on the assumption that the winning process created it
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$mode = 'rb';
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$this->lock_fp = @fopen($this->path . '.lock', $mode);
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}
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else
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{
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// Only need to set mode when the lock file is written
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@chmod($this->path . '.lock', 0666);
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}
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}
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if ($this->lock_fp)
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{
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@flock($this->lock_fp, LOCK_EX);
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}
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return (bool) $this->lock_fp;
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}
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/**
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* Releases the lock.
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*
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* The lock must have been previously obtained, that is, acquire() call
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* was issued and returned true.
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*
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* Note: Attempting to release a lock that is already released,
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* that is, calling release() multiple times, is harmless.
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*
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* @return null
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*/
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public function release()
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{
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if ($this->lock_fp)
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{
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@flock($this->lock_fp, LOCK_UN);
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fclose($this->lock_fp);
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$this->lock_fp = null;
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}
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}
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}
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