EDIT 2017/01 - J'ai écrit une bibliothèque pour faire cela en PHP> = 7.0 https://github.com/DaveRandom/Resume
EDIT 2016/02 - Code complètement réécrit en un ensemble d'outils modulaires, un exemple d'utilisation, plutôt qu'une fonction monolithique. Les corrections mentionnées dans les commentaires ci-dessous ont été intégrées.
Une solution testée et fonctionnelle (largement basée sur la réponse de Theo ci-dessus) qui traite des téléchargements avec reprise, dans un ensemble de quelques outils autonomes. Ce code nécessite PHP 5.4 ou version ultérieure.
Cette solution ne peut toujours faire face qu'à une plage par requête, mais en toute circonstance avec un navigateur standard auquel je pense, cela ne devrait pas poser de problème.
<?php
/**
* Get the value of a header in the current request context
*
* @param string $name Name of the header
* @return string|null Returns null when the header was not sent or cannot be retrieved
*/
function get_request_header($name)
{
$name = strtoupper($name);
// IIS/Some Apache versions and configurations
if (isset($_SERVER['HTTP_' . $name])) {
return trim($_SERVER['HTTP_' . $name]);
}
// Various other SAPIs
foreach (apache_request_headers() as $header_name => $value) {
if (strtoupper($header_name) === $name) {
return trim($value);
}
}
return null;
}
class NonExistentFileException extends \RuntimeException {}
class UnreadableFileException extends \RuntimeException {}
class UnsatisfiableRangeException extends \RuntimeException {}
class InvalidRangeHeaderException extends \RuntimeException {}
class RangeHeader
{
/**
* The first byte in the file to send (0-indexed), a null value indicates the last
* $end bytes
*
* @var int|null
*/
private $firstByte;
/**
* The last byte in the file to send (0-indexed), a null value indicates $start to
* EOF
*
* @var int|null
*/
private $lastByte;
/**
* Create a new instance from a Range header string
*
* @param string $header
* @return RangeHeader
*/
public static function createFromHeaderString($header)
{
if ($header === null) {
return null;
}
if (!preg_match('/^\s*(\S+)\s*(\d*)\s*-\s*(\d*)\s*(?:,|$)/', $header, $info)) {
throw new InvalidRangeHeaderException('Invalid header format');
} else if (strtolower($info[1]) !== 'bytes') {
throw new InvalidRangeHeaderException('Unknown range unit: ' . $info[1]);
}
return new self(
$info[2] === '' ? null : $info[2],
$info[3] === '' ? null : $info[3]
);
}
/**
* @param int|null $firstByte
* @param int|null $lastByte
* @throws InvalidRangeHeaderException
*/
public function __construct($firstByte, $lastByte)
{
$this->firstByte = $firstByte === null ? $firstByte : (int)$firstByte;
$this->lastByte = $lastByte === null ? $lastByte : (int)$lastByte;
if ($this->firstByte === null && $this->lastByte === null) {
throw new InvalidRangeHeaderException(
'Both start and end position specifiers empty'
);
} else if ($this->firstByte < 0 || $this->lastByte < 0) {
throw new InvalidRangeHeaderException(
'Position specifiers cannot be negative'
);
} else if ($this->lastByte !== null && $this->lastByte < $this->firstByte) {
throw new InvalidRangeHeaderException(
'Last byte cannot be less than first byte'
);
}
}
/**
* Get the start position when this range is applied to a file of the specified size
*
* @param int $fileSize
* @return int
* @throws UnsatisfiableRangeException
*/
public function getStartPosition($fileSize)
{
$size = (int)$fileSize;
if ($this->firstByte === null) {
return ($size - 1) - $this->lastByte;
}
if ($size <= $this->firstByte) {
throw new UnsatisfiableRangeException(
'Start position is after the end of the file'
);
}
return $this->firstByte;
}
/**
* Get the end position when this range is applied to a file of the specified size
*
* @param int $fileSize
* @return int
* @throws UnsatisfiableRangeException
*/
public function getEndPosition($fileSize)
{
$size = (int)$fileSize;
if ($this->lastByte === null) {
return $size - 1;
}
if ($size <= $this->lastByte) {
throw new UnsatisfiableRangeException(
'End position is after the end of the file'
);
}
return $this->lastByte;
}
/**
* Get the length when this range is applied to a file of the specified size
*
* @param int $fileSize
* @return int
* @throws UnsatisfiableRangeException
*/
public function getLength($fileSize)
{
$size = (int)$fileSize;
return $this->getEndPosition($size) - $this->getStartPosition($size) + 1;
}
/**
* Get a Content-Range header corresponding to this Range and the specified file
* size
*
* @param int $fileSize
* @return string
*/
public function getContentRangeHeader($fileSize)
{
return 'bytes ' . $this->getStartPosition($fileSize) . '-'
. $this->getEndPosition($fileSize) . '/' . $fileSize;
}
}
class PartialFileServlet
{
/**
* The range header on which the data transmission will be based
*
* @var RangeHeader|null
*/
private $range;
/**
* @param RangeHeader $range Range header on which the transmission will be based
*/
public function __construct(RangeHeader $range = null)
{
$this->range = $range;
}
/**
* Send part of the data in a seekable stream resource to the output buffer
*
* @param resource $fp Stream resource to read data from
* @param int $start Position in the stream to start reading
* @param int $length Number of bytes to read
* @param int $chunkSize Maximum bytes to read from the file in a single operation
*/
private function sendDataRange($fp, $start, $length, $chunkSize = 8192)
{
if ($start > 0) {
fseek($fp, $start, SEEK_SET);
}
while ($length) {
$read = ($length > $chunkSize) ? $chunkSize : $length;
$length -= $read;
echo fread($fp, $read);
}
}
/**
* Send the headers that are included regardless of whether a range was requested
*
* @param string $fileName
* @param int $contentLength
* @param string $contentType
*/
private function sendDownloadHeaders($fileName, $contentLength, $contentType)
{
header('Content-Type: ' . $contentType);
header('Content-Length: ' . $contentLength);
header('Content-Disposition: attachment; filename="' . $fileName . '"');
header('Accept-Ranges: bytes');
}
/**
* Send data from a file based on the current Range header
*
* @param string $path Local file system path to serve
* @param string $contentType MIME type of the data stream
*/
public function sendFile($path, $contentType = 'application/octet-stream')
{
// Make sure the file exists and is a file, otherwise we are wasting our time
$localPath = realpath($path);
if ($localPath === false || !is_file($localPath)) {
throw new NonExistentFileException(
$path . ' does not exist or is not a file'
);
}
// Make sure we can open the file for reading
if (!$fp = fopen($localPath, 'r')) {
throw new UnreadableFileException(
'Failed to open ' . $localPath . ' for reading'
);
}
$fileSize = filesize($localPath);
if ($this->range == null) {
// No range requested, just send the whole file
header('HTTP/1.1 200 OK');
$this->sendDownloadHeaders(basename($localPath), $fileSize, $contentType);
fpassthru($fp);
} else {
// Send the request range
header('HTTP/1.1 206 Partial Content');
header('Content-Range: ' . $this->range->getContentRangeHeader($fileSize));
$this->sendDownloadHeaders(
basename($localPath),
$this->range->getLength($fileSize),
$contentType
);
$this->sendDataRange(
$fp,
$this->range->getStartPosition($fileSize),
$this->range->getLength($fileSize)
);
}
fclose($fp);
}
}
Exemple d'utilisation:
<?php
$path = '/local/path/to/file.ext';
$contentType = 'application/octet-stream';
// Avoid sending unexpected errors to the client - we should be serving a file,
// we don't want to corrupt the data we send
ini_set('display_errors', '0');
try {
$rangeHeader = RangeHeader::createFromHeaderString(get_request_header('Range'));
(new PartialFileServlet($rangeHeader))->sendFile($path, $contentType);
} catch (InvalidRangeHeaderException $e) {
header("HTTP/1.1 400 Bad Request");
} catch (UnsatisfiableRangeException $e) {
header("HTTP/1.1 416 Range Not Satisfiable");
} catch (NonExistentFileException $e) {
header("HTTP/1.1 404 Not Found");
} catch (UnreadableFileException $e) {
header("HTTP/1.1 500 Internal Server Error");
}
// It's usually a good idea to explicitly exit after sending a file to avoid sending any
// extra data on the end that might corrupt the file
exit;