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<?php
namespace ParagonIE\ConstantTime;
/**
* Copyright (c) 2016 - 2017 Paragon Initiative Enterprises.
* Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
*
* 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.
*/
/**
* Class Binary
*
* Binary string operators that don't choke on
* mbstring.func_overload
*
* @package ParagonIE\ConstantTime
*/
abstract class Binary
{
/**
* Safe string length
*
* @ref mbstring.func_overload
*
* @param string $str
* @return int
*/
public static function safeStrlen($str)
{
if (\function_exists('mb_strlen')) {
return (int) \mb_strlen($str, '8bit');
} else {
return (int) \strlen($str);
}
}
/**
* Safe substring
*
* @ref mbstring.func_overload
*
* @staticvar boolean $exists
* @param string $str
* @param int $start
* @param int $length
* @return string
* @throws \TypeError
*/
public static function safeSubstr(
$str,
$start = 0,
$length = \null
) {
if (\function_exists('mb_substr')) {
// mb_substr($str, 0, null, '8bit') returns an empty string on PHP
// 5.3, so we have to find the length ourselves.
if (\is_null($length)) {
if ($start >= 0) {
$length = self::safeStrlen($str) - $start;
} else {
$length = -$start;
}
}
// $length calculation above might result in a 0-length string
if ($length === 0) {
return '';
}
return \mb_substr($str, $start, $length, '8bit');
}
if ($length === 0) {
return '';
}
// Unlike mb_substr(), substr() doesn't accept null for length
if (!is_null($length)) {
return \substr($str, $start, $length);
} else {
return \substr($str, $start);
}
}
}
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