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|
<?php
/**
* SPDX-FileCopyrightText: 2020 Nextcloud GmbH and Nextcloud contributors
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
namespace OC\Files\Stream;
use Icewind\Streams\File;
use Icewind\Streams\Wrapper;
/**
* 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 bool $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|closed-resource */
private $current;
/** @var int $offset offset of the current chunk */
private int $offset = 0;
/** @var int $length length of the current chunk */
private int $length = 0;
/** @var int $totalSize size of the full stream */
private int $totalSize = 0;
private bool $needReconnect = false;
private function reconnect(int $start): bool {
$this->needReconnect = false;
$range = $start . '-';
if ($this->hasOpenStream()) {
fclose($this->current);
}
$stream = ($this->openCallback)($range);
if ($stream === false) {
$this->current = null;
return false;
}
$this->current = $stream;
$responseHead = stream_get_meta_data($this->current)['wrapper_data'];
while ($responseHead instanceof Wrapper) {
$wrapperOptions = stream_context_get_options($responseHead->context);
foreach ($wrapperOptions as $options) {
if (isset($options['source']) && is_resource($options['source'])) {
$responseHead = stream_get_meta_data($options['source'])['wrapper_data'];
continue 2;
}
}
throw new \Exception('Failed to get source stream from stream wrapper of ' . get_class($responseHead));
}
$rangeHeaders = array_values(array_filter($responseHead, function ($v) {
return preg_match('#^content-range:#i', $v) === 1;
}));
if (!$rangeHeaders) {
$this->current = null;
return false;
}
$contentRange = $rangeHeaders[0];
$content = trim(explode(':', $contentRange)[1]);
$range = trim(explode(' ', $content)[1]);
$begin = intval(explode('-', $range)[0]);
$length = intval(explode('/', $range)[1]);
if ($begin !== $start) {
$this->current = null;
return false;
}
$this->offset = $begin;
$this->length = $length;
if ($start === 0) {
$this->totalSize = $length;
}
return true;
}
/**
* @return ?resource
*/
private function getCurrent() {
if ($this->needReconnect) {
$this->reconnect($this->offset);
}
if (is_resource($this->current)) {
return $this->current;
} else {
return null;
}
}
/**
* @return bool
* @psalm-assert-if-true resource $this->current
*/
private function hasOpenStream(): bool {
return is_resource($this->current);
}
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->getCurrent()) {
return false;
}
$ret = fread($this->getCurrent(), $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;
} else {
$this->offset = $offset;
}
break;
case SEEK_CUR:
if ($offset === 0) {
return true;
} else {
$this->offset += $offset;
}
break;
case SEEK_END:
if ($this->length === 0) {
return false;
} elseif ($this->length + $offset === $this->offset) {
return true;
} else {
$this->offset = $this->length + $offset;
}
break;
}
if ($this->hasOpenStream()) {
fclose($this->current);
}
$this->current = null;
$this->needReconnect = true;
return true;
}
public function stream_tell() {
return $this->offset;
}
public function stream_stat() {
if ($this->getCurrent()) {
$stat = fstat($this->getCurrent());
if ($stat) {
$stat['size'] = $this->totalSize;
}
return $stat;
} else {
return false;
}
}
public function stream_eof() {
if ($this->getCurrent()) {
return feof($this->getCurrent());
} else {
return true;
}
}
public function stream_close() {
if ($this->hasOpenStream()) {
fclose($this->current);
}
$this->current = null;
}
public function stream_write($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
}
}
|
