owncloud/core

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lib/private/Files/Stream/Quota.php

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<?php
/**
 * @author Jörn Friedrich Dreyer <jfd@butonic.de>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Vincent Petry <pvince81@owncloud.com>
 *
 * @copyright Copyright (c) 2018, ownCloud GmbH
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * 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, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

namespace OC\Files\Stream;

/**
 * stream wrapper limits the amount of data that can be written to a stream
 *
 * usage: void \OC\Files\Stream\Quota::register($id, $stream, $limit)
 * or:    resource \OC\Files\Stream\Quota::wrap($stream, $limit)
 */
class Quota {
    private static $streams = [];

    /**
     * @var resource $source
     */
    private $source;

    /**
     * @var int $limit
     */
    private $limit;

    /**
     * @param string $id
     * @param resource $stream
     * @param int $limit
     */
    public static function register($id, $stream, $limit) {
        self::$streams[$id] = [$stream, $limit];
    }

    /**
     * remove all registered streams
     */
    public static function clear() {
        self::$streams = [];
    }

    /**
     * @param resource $stream
     * @param int $limit
     * @return resource
     */
    public static function wrap($stream, $limit) {
        $id = \uniqid();
        self::register($id, $stream, $limit);
        $meta = \stream_get_meta_data($stream);
        return \fopen('quota://' . $id, $meta['mode']);
    }

    public function stream_open($path, $mode, $options, &$opened_path) {
        $id = \substr($path, \strlen('quota://'));
        if (isset(self::$streams[$id])) {
            list($this->source, $this->limit) = self::$streams[$id];
            return true;
        } else {
            return false;
        }
    }

    public function stream_seek($offset, $whence = SEEK_SET) {
        if ($whence === SEEK_END) {
            // go to the end to find out last position's offset
            $oldOffset = $this->stream_tell();
            if (\fseek($this->source, 0, $whence) !== 0) {
                return false;
            }
            $whence = SEEK_SET;
            $offset = $this->stream_tell() + $offset;
            $this->limit += $oldOffset - $offset;
        } elseif ($whence === SEEK_SET) {
            $this->limit += $this->stream_tell() - $offset;
        } else {
            $this->limit -= $offset;
        }
        // this wrapper needs to return "true" for success.
        // the fseek call itself returns 0 on success
        return \fseek($this->source, $offset, $whence) === 0;
    }

    public function stream_tell() {
        return \ftell($this->source);
    }

    public function stream_read($count) {
        $this->limit -= $count;
        return \fread($this->source, $count);
    }

    public function stream_write($data) {
        $size = \strlen($data);
        if ($size > $this->limit) {
            $data = \substr($data, 0, $this->limit);
            $size = $this->limit;
        }
        $this->limit -= $size;
        return \fwrite($this->source, $data);
    }

    public function stream_set_option($option, $arg1, $arg2) {
        switch ($option) {
            case STREAM_OPTION_BLOCKING:
                \stream_set_blocking($this->source, $arg1);
                break;
            case STREAM_OPTION_READ_TIMEOUT:
                \stream_set_timeout($this->source, $arg1, $arg2);
                break;
            case STREAM_OPTION_WRITE_BUFFER:
                \stream_set_write_buffer($this->source, $arg1);
        }
    }

    public function stream_stat() {
        return \fstat($this->source);
    }

    public function stream_lock($mode) {
        return \flock($this->source, $mode);
    }

    public function stream_flush() {
        return \fflush($this->source);
    }

    public function stream_eof() {
        return \feof($this->source);
    }

    public function stream_close() {
        \fclose($this->source);
    }
}