updraftplus / includes / class-partialfileservlet.php

class-partialfileservlet.php in UpdraftPlus: WP Backup & Migration Plugin 1.16.5, at includes/class-partialfileservlet.php

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1	<?php
2
3	// https://stackoverflow.com/questions/157318/resumable-downloads-when-using-php-to-send-the-file
4	// User: DaveRandom
5
6	if (!class_exists('UpdraftPlus_NonExistentFileException')):
7	class UpdraftPlus_NonExistentFileException extends RuntimeException {}
8	endif;
9
10	if (!class_exists('UpdraftPlus_UnreadableFileException')):
11	class UpdraftPlus_UnreadableFileException extends RuntimeException {}
12	endif;
13
14	if (!class_exists('UpdraftPlus_UnsatisfiableRangeException')):
15	class UpdraftPlus_UnsatisfiableRangeException extends RuntimeException {}
16	endif;
17
18	if (!class_exists('UpdraftPlus_InvalidRangeHeaderException')):
19	class UpdraftPlus_InvalidRangeHeaderException extends RuntimeException {}
20	endif;
21
22	class UpdraftPlus_RangeHeader
23	{
24	/**
25	* The first byte in the file to send (0-indexed), a null value indicates the last
26	* $end bytes
27	*
28	* @var int\|null
29	*/
30	private $firstByte;
31
32	/**
33	* The last byte in the file to send (0-indexed), a null value indicates $start to
34	* EOF
35	*
36	* @var int\|null
37	*/
38	private $lastByte;
39
40	/**
41	* Create a new instance from a Range header string
42	*
43	* @param string $header
44	* @return UpdraftPlus_RangeHeader
45	*/
46	public static function createFromHeaderString($header)
47	{
48	if ($header === null) {
49	return null;
50	}
51	if (!preg_match('/^\s([A-Za-z]+)\s=\s(\d)\s-\s(\d)\s(?:,\|$)/', $header, $info)) {
52	throw new UpdraftPlus_InvalidRangeHeaderException('Invalid header format');
53	} else if (strtolower($info[1]) !== 'bytes') {
54	throw new UpdraftPlus_InvalidRangeHeaderException('Unknown range unit: ' . $info[1]);
55	}
56
57	return new self(
58	$info[2] === '' ? null : $info[2],
59	$info[3] === '' ? null : $info[3]
60	);
61	}
62
63	/**
64	* @param int\|null $firstByte
65	* @param int\|null $lastByte
66	* @throws UpdraftPlus_InvalidRangeHeaderException
67	*/
68	public function __construct($firstByte, $lastByte)
69	{
70	$this->firstByte = $firstByte === null ? $firstByte : (int)$firstByte;
71	$this->lastByte = $lastByte === null ? $lastByte : (int)$lastByte;
72
73	if ($this->firstByte === null && $this->lastByte === null) {
74	throw new UpdraftPlus_InvalidRangeHeaderException(
75	'Both start and end position specifiers empty'
76	);
77	} else if ($this->firstByte < 0 \|\| $this->lastByte < 0) {
78	throw new UpdraftPlus_InvalidRangeHeaderException(
79	'Position specifiers cannot be negative'
80	);
81	} else if ($this->lastByte !== null && $this->lastByte < $this->firstByte) {
82	throw new UpdraftPlus_InvalidRangeHeaderException(
83	'Last byte cannot be less than first byte'
84	);
85	}
86	}
87
88	/**
89	* Get the start position when this range is applied to a file of the specified size
90	*
91	* @param int $fileSize
92	* @return int
93	* @throws UpdraftPlus_UnsatisfiableRangeException
94	*/
95	public function getStartPosition($fileSize)
96	{
97	$size = (int)$fileSize;
98
99	if ($this->firstByte === null) {
100	return ($size - 1) - $this->lastByte;
101	}
102
103	if ($size <= $this->firstByte) {
104	throw new UpdraftPlus_UnsatisfiableRangeException(
105	'Start position is after the end of the file'
106	);
107	}
108
109	return $this->firstByte;
110	}
111
112	/**
113	* Get the end position when this range is applied to a file of the specified size
114	*
115	* @param int $fileSize
116	* @return int
117	* @throws UpdraftPlus_UnsatisfiableRangeException
118	*/
119	public function getEndPosition($fileSize)
120	{
121	$size = (int)$fileSize;
122
123	if ($this->lastByte === null) {
124	return $size - 1;
125	}
126
127	if ($size <= $this->lastByte) {
128	throw new UpdraftPlus_UnsatisfiableRangeException(
129	'End position is after the end of the file'
130	);
131	}
132
133	return $this->lastByte;
134	}
135
136	/**
137	* Get the length when this range is applied to a file of the specified size
138	*
139	* @param int $fileSize
140	* @return int
141	* @throws UpdraftPlus_UnsatisfiableRangeException
142	*/
143	public function getLength($fileSize)
144	{
145	$size = (int)$fileSize;
146
147	return $this->getEndPosition($size) - $this->getStartPosition($size) + 1;
148	}
149
150	/**
151	* Get a Content-Range header corresponding to this Range and the specified file
152	* size
153	*
154	* @param int $fileSize
155	* @return string
156	*/
157	public function getContentRangeHeader($fileSize)
158	{
159	return 'bytes ' . $this->getStartPosition($fileSize) . '-'
160	. $this->getEndPosition($fileSize) . '/' . $fileSize;
161	}
162	}
163
164	class UpdraftPlus_PartialFileServlet
165	{
166	/**
167	* The range header on which the data transmission will be based
168	*
169	* @var UpdraftPlus_RangeHeader\|null
170	*/
171	private $range;
172
173	/**
174	* @param UpdraftPlus_RangeHeader $range Range header on which the transmission will be based
175	*/
176	public function __construct($range = null)
177	{
178	$this->range = $range;
179	}
180
181	/**
182	* Send part of the data in a seekable stream resource to the output buffer
183	*
184	* @param resource $fp Stream resource to read data from
185	* @param int $start Position in the stream to start reading
186	* @param int $length Number of bytes to read
187	* @param int $chunkSize Maximum bytes to read from the file in a single operation
188	*/
189	private function sendDataRange($fp, $start, $length, $chunkSize = 2097152)
190	{
191	if ($start > 0) {
192	fseek($fp, $start, SEEK_SET);
193	}
194
195	while ($length) {
196	$read = ($length > $chunkSize) ? $chunkSize : $length;
197	$length -= $read;
198	echo fread($fp, $read);
199	}
200	}
201
202	/**
203	* Send the headers that are included regardless of whether a range was requested
204	*
205	* @param string $fileName
206	* @param int $contentLength
207	* @param string $contentType
208	*/
209	private function sendDownloadHeaders($fileName, $contentLength, $contentType)
210	{
211	header('Content-Type: ' . $contentType);
212	header('Content-Length: ' . $contentLength);
213	header('Content-Disposition: attachment; filename="' . $fileName . '"');
214	header('Accept-Ranges: bytes');
215	}
216
217	/**
218	* Send data from a file based on the current Range header
219	*
220	* @param string $path Local file system path to serve
221	* @param string $contentType MIME type of the data stream
222	*/
223	public function sendFile($path, $contentType = 'application/octet-stream')
224	{
225	// Make sure the file exists and is a file, otherwise we are wasting our time
226	$localPath = realpath($path);
227	if ($localPath === false \|\| !is_file($localPath)) {
228	throw new UpdraftPlus_NonExistentFileException(
229	$path . ' does not exist or is not a file'
230	);
231	}
232
233	// Make sure we can open the file for reading
234	if (!$fp = fopen($localPath, 'r')) {
235	throw new UpdraftPlus_UnreadableFileException(
236	'Failed to open ' . $localPath . ' for reading'
237	);
238	}
239
240	$fileSize = filesize($localPath);
241
242	if ($this->range == null) {
243	// No range requested, just send the whole file
244	header('HTTP/1.1 200 OK');
245	$this->sendDownloadHeaders(basename($localPath), $fileSize, $contentType);
246
247	fpassthru($fp);
248	} else {
249	// Send the request range
250	header('HTTP/1.1 206 Partial Content');
251	header('Content-Range: ' . $this->range->getContentRangeHeader($fileSize));
252	$this->sendDownloadHeaders(
253	basename($localPath),
254	$this->range->getLength($fileSize),
255	$contentType
256	);
257
258	$this->sendDataRange(
259	$fp,
260	$this->range->getStartPosition($fileSize),
261	$this->range->getLength($fileSize)
262	);
263	}
264
265	fclose($fp);
266	}
267	}