<?php

/**

 * Random_* Compatibility Library 

 * for using the new PHP 7 random_* API in PHP 5 projects

 * 

 * The MIT License (MIT)

 * 

 * Copyright (c) 2015 Paragon Initiative Enterprises

 * 

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 * 

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE.

 */

if ( ! is_callable( 'random_bytes' ) ):

/**

 * If the libsodium PHP extension is loaded, we'll use it above any other

 * solution.

 *

 * libsodium-php project:

 * @ref https://github.com/jedisct1/libsodium-php

 *

 * @param int $bytes

 *

 * @throws Exception

 *

 * @return string

 */

function random_bytes($bytes)

{

    try {

        $bytes = RandomCompat_intval($bytes);

    } catch (TypeError $ex) {

        throw new TypeError(

            'random_bytes(): $bytes must be an integer'

        );

    }

    if ($bytes < 1) {

        throw new Error(

            'Length must be greater than 0'

        );

    }

    /**

     * \Sodium\randombytes_buf() doesn't allow more than 2147483647 bytes to be

     * generated in one invocation.

     */

    if ($bytes > 2147483647) {

        $buf = '';

        for ($i = 0; $i < $bytes; $i += 1073741824) {

            $n = ($bytes - $i) > 1073741824

                ? 1073741824

                : $bytes - $i;

            $buf .= \Sodium\randombytes_buf($n);

        }

    } else {

        $buf = \Sodium\randombytes_buf($bytes);

    }

    if ($buf !== false) {

        if (RandomCompat_strlen($buf) === $bytes) {

            return $buf;

        }

    }

    /**

     * If we reach here, PHP has failed us.

     */

    throw new Exception(

        'Could not gather sufficient random data'

    );

}

endif;