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<?php
/**
*
* @copyright Copyright (c) 2020, Lukas Stabe (lukas@stabe.de)
*
* @license GNU AGPL version 3 or any later version
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
namespace OC\Files\Stream;
use Icewind\Streams\File;
/**
* A stream wrapper that uses http range requests to provide a seekable stream for http reading
*/
class SeekableHttpStream implements File {
private const PROTOCOL = 'httpseek';
private static $registered = false;
/**
* Registers the stream wrapper using the `httpseek://` url scheme
* $return void
*/
private static function registerIfNeeded() {
if (!self::$registered) {
stream_wrapper_register(
self::PROTOCOL,
self::class
);
self::$registered = true;
}
}
/**
* Open a readonly-seekable http stream
*
* The provided callback will be called with byte range and should return an http stream for the requested range
*
* @param callable $callback
* @return false|resource
*/
public static function open(callable $callback) {
$context = stream_context_create([
SeekableHttpStream::PROTOCOL => [
'callback' => $callback
],
]);
SeekableHttpStream::registerIfNeeded();
return fopen(SeekableHttpStream::PROTOCOL . '://', 'r', false, $context);
}
/** @var resource */
public $context;
/** @var callable */
private $openCallback;
/** @var resource */
private $current;
/** @var int */
private $offset = 0;
private function reconnect(int $start) {
$range = $start . '-';
if ($this->current != null) {
fclose($this->current);
}
$this->current = ($this->openCallback)($range);
if ($this->current === false) {
return false;
}
$responseHead = stream_get_meta_data($this->current)['wrapper_data'];
$rangeHeaders = array_values(array_filter($responseHead, function ($v) {
return preg_match('#^content-range:#i', $v) === 1;
}));
if (!$rangeHeaders) {
return false;
}
$contentRange = $rangeHeaders[0];
$content = trim(explode(':', $contentRange)[1]);
$range = trim(explode(' ', $content)[1]);
$begin = intval(explode('-', $range)[0]);
if ($begin !== $start) {
return false;
}
$this->offset = $begin;
return true;
}
public function stream_open($path, $mode, $options, &$opened_path) {
$options = stream_context_get_options($this->context)[self::PROTOCOL];
$this->openCallback = $options['callback'];
return $this->reconnect(0);
}
public function stream_read($count) {
if (!$this->current) {
return false;
}
$ret = fread($this->current, $count);
$this->offset += strlen($ret);
return $ret;
}
public function stream_seek($offset, $whence = SEEK_SET) {
switch ($whence) {
case SEEK_SET:
if ($offset === $this->offset) {
return true;
}
return $this->reconnect($offset);
case SEEK_CUR:
if ($offset === 0) {
return true;
}
return $this->reconnect($this->offset + $offset);
case SEEK_END:
return false;
}
return false;
}
public function stream_tell() {
return $this->offset;
}
public function stream_stat() {
if (is_resource($this->current)) {
return fstat($this->current);
} else {
return false;
}
}
public function stream_eof() {
if (is_resource($this->current)) {
return feof($this->current);
} else {
return true;
}
}
public function stream_close() {
if (is_resource($this->current)) {
fclose($this->current);
}
}
public function stream_write($data) {
return false;
}
public function stream_set_option($option, $arg1, $arg2) {
return false;
}
public function stream_truncate($size) {
return false;
}
public function stream_lock($operation) {
return false;
}
public function stream_flush() {
return; //noop because readonly stream
}
}
|
