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<?php
/**
* Copyright 2017 Facebook, Inc.
*
* You are hereby granted a non-exclusive, worldwide, royalty-free license to
* use, copy, modify, and distribute this software in source code or binary
* form for use in connection with the web services and APIs provided by
* Facebook.
*
* As with any software that integrates with the Facebook platform, your use
* of this software is subject to the Facebook Developer Principles and
* Policies [http://developers.facebook.com/policy/]. This copyright 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.
*
*/
namespace Facebook\PseudoRandomString;
use Facebook\Exceptions\FacebookSDKException;
class UrandomPseudoRandomStringGenerator implements PseudoRandomStringGeneratorInterface
{
use PseudoRandomStringGeneratorTrait;
/**
* @const string The error message when generating the string fails.
*/
const ERROR_MESSAGE = 'Unable to generate a cryptographically secure pseudo-random string from /dev/urandom. ';
/**
* @throws FacebookSDKException
*/
public function __construct()
{
if (ini_get('open_basedir')) {
throw new FacebookSDKException(
static::ERROR_MESSAGE .
'There is an open_basedir constraint that prevents access to /dev/urandom.'
);
}
if (!is_readable('/dev/urandom')) {
throw new FacebookSDKException(
static::ERROR_MESSAGE .
'Unable to read from /dev/urandom.'
);
}
}
/**
* @inheritdoc
*/
public function getPseudoRandomString($length)
{
$this->validateLength($length);
$stream = fopen('/dev/urandom', 'rb');
if (!is_resource($stream)) {
throw new FacebookSDKException(
static::ERROR_MESSAGE .
'Unable to open stream to /dev/urandom.'
);
}
if (!defined('HHVM_VERSION')) {
stream_set_read_buffer($stream, 0);
}
$binaryString = fread($stream, $length);
fclose($stream);
if (!$binaryString) {
throw new FacebookSDKException(
static::ERROR_MESSAGE .
'Stream to /dev/urandom returned no data.'
);
}
return $this->binToHex($binaryString, $length);
}
}
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