1<?php
2/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
3
4/**
5 * DNS Library for handling lookups and updates.
6 *
7 * PHP Version 5
8 *
9 * Copyright (c) 2010, Mike Pultz <mike@mikepultz.com>.
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 *
16 *   * Redistributions of source code must retain the above copyright
17 *     notice, this list of conditions and the following disclaimer.
18 *
19 *   * Redistributions in binary form must reproduce the above copyright
20 *     notice, this list of conditions and the following disclaimer in
21 *     the documentation and/or other materials provided with the
22 *     distribution.
23 *
24 *   * Neither the name of Mike Pultz nor the names of his contributors
25 *     may be used to endorse or promote products derived from this
26 *     software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
31 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
32 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
33 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
34 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
35 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
36 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRIC
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
38 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
39 * POSSIBILITY OF SUCH DAMAGE.
40 *
41 * @category  Networking
42 * @package   Net_DNS2
43 * @author    Mike Pultz <mike@mikepultz.com>
44 * @copyright 2010 Mike Pultz <mike@mikepultz.com>
45 * @license   http://www.opensource.org/licenses/bsd-license.php  BSD License
46 * @version   SVN: $Id$
47 * @link      http://pear.php.net/package/Net_DNS2
48 * @since     File available since Release 1.1.0
49 *
50 */
51
52/**
53 * File-based caching for the Net_DNS2_Cache class
54 *
55 * @category Networking
56 * @package  Net_DNS2
57 * @author   Mike Pultz <mike@mikepultz.com>
58 * @license  http://www.opensource.org/licenses/bsd-license.php  BSD License
59 * @link     http://pear.php.net/package/Net_DNS2
60 * @see      Net_DNS2_Packet
61 *
62 */
63class Net_DNS2_Cache_File extends Net_DNS2_Cache
64{
65    /**
66     * open a cache object
67     *
68     * @param string  $cache_file path to a file to use for cache storage
69     * @param integer $size       the size of the shared memory segment to create
70     * @param string  $serializer the name of the cache serialize to use
71     *
72     * @throws Net_DNS2_Exception
73     * @access public
74     * @return void
75     *
76     */
77    public function open($cache_file, $size, $serializer)
78    {
79        $this->cache_size       = $size;
80        $this->cache_file       = $cache_file;
81        $this->cache_serializer = $serializer;
82
83        //
84        // check that the file exists first
85        //
86        if ( ($this->cache_opened == false)
87            && (file_exists($this->cache_file) == true)
88            && (filesize($this->cache_file) > 0)
89        ) {
90            //
91            // open the file for reading
92            //
93            $fp = @fopen($this->cache_file, 'r');
94            if ($fp !== false) {
95
96                //
97                // lock the file just in case
98                //
99                flock($fp, LOCK_EX);
100
101                //
102                // read the file contents
103                //
104                $data = fread($fp, filesize($this->cache_file));
105
106                $decoded = null;
107
108                if ($this->cache_serializer == 'json') {
109
110                    $decoded = json_decode($data, true);
111                } else {
112
113                    $decoded = unserialize($data);
114                }
115
116                if (is_array($decoded) == true) {
117
118                    $this->cache_data = $decoded;
119                } else {
120
121                    $this->cache_data = array();
122                }
123
124                //
125                // unlock
126                //
127                flock($fp, LOCK_UN);
128
129                //
130                // close the file
131                //
132                fclose($fp);
133
134                //
135                // clean up the data
136                //
137                $this->clean();
138
139                //
140                // mark this so we don't read this contents more than once per instance.
141                //
142                $this->cache_opened = true;
143            }
144        }
145    }
146
147    /**
148     * Destructor
149     *
150     * @access public
151     *
152     */
153    public function __destruct()
154    {
155        //
156        // if there's no cache file set, then there's nothing to do
157        //
158        if (strlen($this->cache_file) == 0) {
159            return;
160        }
161
162        //
163        // open the file for reading/writing
164        //
165        $fp = fopen($this->cache_file, 'a+');
166        if ($fp !== false) {
167
168            //
169            // lock the file just in case
170            //
171            flock($fp, LOCK_EX);
172
173            //
174            // seek to the start of the file to read
175            //
176            fseek($fp, 0, SEEK_SET);
177
178            //
179            // read the file contents
180            //
181            $data = @fread($fp, filesize($this->cache_file));
182            if ( ($data !== false) && (strlen($data) > 0) ) {
183
184                //
185                // unserialize and store the data
186                //
187                $c = $this->cache_data;
188
189                $decoded = null;
190
191                if ($this->cache_serializer == 'json') {
192
193                    $decoded = json_decode($data, true);
194                } else {
195
196                    $decoded = unserialize($data);
197                }
198
199                if (is_array($decoded) == true) {
200
201                    $this->cache_data = array_merge($c, $decoded);
202                }
203            }
204
205            //
206            // trucate the file
207            //
208            ftruncate($fp, 0);
209
210            //
211            // clean the data
212            //
213            $this->clean();
214
215            //
216            // resize the data
217            //
218            $data = $this->resize();
219            if (!is_null($data)) {
220
221                //
222                // write the file contents
223                //
224                fwrite($fp, $data);
225            }
226
227            //
228            // unlock
229            //
230            flock($fp, LOCK_UN);
231
232            //
233            // close the file
234            //
235            fclose($fp);
236        }
237    }
238};
239
240/*
241 * Local variables:
242 * tab-width: 4
243 * c-basic-offset: 4
244 * c-hanging-comment-ender-p: nil
245 * End:
246 */
247?>
248