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<?php
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namespace ParagonIE\ConstantTime;
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/**
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* Copyright (c) 2016 - 2017 Paragon Initiative Enterprises.
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* Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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/**
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* Class Binary
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*
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* Binary string operators that don't choke on
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* mbstring.func_overload
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*
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* @package ParagonIE\ConstantTime
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*/
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abstract class Binary
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{
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/**
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* Safe string length
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*
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* @ref mbstring.func_overload
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*
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* @param string $str
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* @return int
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*/
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public static function safeStrlen($str)
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{
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if (\function_exists('mb_strlen')) {
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return (int) \mb_strlen($str, '8bit');
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} else {
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return (int) \strlen($str);
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}
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}
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/**
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* Safe substring
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*
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* @ref mbstring.func_overload
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*
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* @staticvar boolean $exists
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* @param string $str
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* @param int $start
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* @param int $length
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* @return string
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* @throws \TypeError
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*/
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public static function safeSubstr(
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$str,
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$start = 0,
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$length = \null
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) {
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if (\function_exists('mb_substr')) {
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// mb_substr($str, 0, null, '8bit') returns an empty string on PHP
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// 5.3, so we have to find the length ourselves.
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if (\is_null($length)) {
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if ($start >= 0) {
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$length = self::safeStrlen($str) - $start;
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} else {
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$length = -$start;
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}
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}
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// $length calculation above might result in a 0-length string
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if ($length === 0) {
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return '';
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}
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return \mb_substr($str, $start, $length, '8bit');
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}
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if ($length === 0) {
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return '';
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}
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// Unlike mb_substr(), substr() doesn't accept null for length
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if (!is_null($length)) {
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return \substr($str, $start, $length);
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} else {
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return \substr($str, $start);
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}
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}
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}
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