From f08c28c77a585e35cc17a2248ba61428275ccdd7 Mon Sep 17 00:00:00 2001
From: Oleg Pudeyev <oleg@bsdpower.com>
Date: Tue, 4 Dec 2012 01:59:27 -0500
Subject: [ticket/10103] Factor out flock lock class.

PHPBB3-10103
---
 phpBB/includes/lock/flock.php | 124 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 phpBB/includes/lock/flock.php

(limited to 'phpBB/includes/lock/flock.php')

diff --git a/phpBB/includes/lock/flock.php b/phpBB/includes/lock/flock.php
new file mode 100644
index 0000000000..e24a5f3e1c
--- /dev/null
+++ b/phpBB/includes/lock/flock.php
@@ -0,0 +1,124 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2012 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* File locking class
+* @package phpBB3
+*/
+class phpbb_lock_flock
+{
+	/**
+	* Path to the file access to which is controlled
+	*
+	* @var string
+	*/
+	private $path;
+
+	/**
+	* File pointer for the lock file
+	* @var string
+	*/
+	private $lock_fp;
+
+	/**
+	* Creates an instance of the lock.
+	*
+	* You have to call acquire() to actually create the lock.
+	*
+	* @param	string	$path	Path to the file access to which is controlled
+	*/
+	public function __construct($path)
+	{
+		$this->path = $path;
+		$this->lock_fp = null;
+	}
+
+	/**
+	* Tries to acquire the lock.
+	*
+	* As a lock may only be held by one process at a time, lock
+	* acquisition may fail if another process is holding the lock.
+	*
+	* @return	bool			true if lock was acquired
+	*							false otherwise
+	*/
+	public function acquire()
+	{
+		if ($this->locked)
+		{
+			return false;
+		}
+
+		// For systems that can't have two processes opening
+		// one file for writing simultaneously
+		if (file_exists($this->path . '.lock'))
+		{
+			$mode = 'rb';
+		}
+		else
+		{
+			$mode = 'wb';
+		}
+
+		$this->lock_fp = @fopen($this->path . '.lock', $mode);
+
+		if ($mode == 'wb')
+		{
+			if (!$this->lock_fp)
+			{
+				// Two processes may attempt to create lock file at the same time.
+				// Have the losing process try opening the lock file again for reading
+				// on the assumption that the winning process created it
+				$mode = 'rb';
+				$this->lock_fp = @fopen($this->path . '.lock', $mode);
+			}
+			else
+			{
+				// Only need to set mode when the lock file is written
+				@chmod($this->path . '.lock', 0666);
+			}
+		}
+
+		if ($this->lock_fp)
+		{
+			@flock($this->lock_fp, LOCK_EX);
+		}
+
+		return (bool) $this->lock_fp;
+	}
+
+	/**
+	* Releases the lock.
+	*
+	* The lock must have been previously obtained, that is, acquire() call
+	* was issued and returned true.
+	*
+	* Note: Attempting to release a lock that is already released,
+	* that is, calling release() multiple times, is harmless.
+	*
+	* @return null
+	*/
+	public function release()
+	{
+		if ($this->lock_fp)
+		{
+			@flock($this->lock_fp, LOCK_UN);
+			fclose($this->lock_fp);
+			$this->lock_fp = null;
+		}
+	}
+}
-- 
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