1<?php
2declare(strict_types=1);
3namespace ParagonIE\ConstantTime;
4
5use TypeError;
6
7/**
8 *  Copyright (c) 2016 - 2022 Paragon Initiative Enterprises.
9 *  Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
10 *
11 *  Permission is hereby granted, free of charge, to any person obtaining a copy
12 *  of this software and associated documentation files (the "Software"), to deal
13 *  in the Software without restriction, including without limitation the rights
14 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
15 *  copies of the Software, and to permit persons to whom the Software is
16 *  furnished to do so, subject to the following conditions:
17 *
18 *  The above copyright notice and this permission notice shall be included in all
19 *  copies or substantial portions of the Software.
20 *
21 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
22 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
23 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
24 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
25 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
26 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
27 *  SOFTWARE.
28 */
29
30/**
31 * Class Binary
32 *
33 * Binary string operators that don't choke on
34 * mbstring.func_overload
35 *
36 * @package ParagonIE\ConstantTime
37 */
38abstract class Binary
39{
40    /**
41     * Safe string length
42     *
43     * @ref mbstring.func_overload
44     *
45     * @param string $str
46     * @return int
47     */
48    public static function safeStrlen(
49        #[\SensitiveParameter]
50        string $str
51    ): int {
52        if (\function_exists('mb_strlen')) {
53            // mb_strlen in PHP 7.x can return false.
54            /** @psalm-suppress RedundantCast */
55            return (int) \mb_strlen($str, '8bit');
56        } else {
57            return \strlen($str);
58        }
59    }
60
61    /**
62     * Safe substring
63     *
64     * @ref mbstring.func_overload
65     *
66     * @staticvar boolean $exists
67     * @param string $str
68     * @param int $start
69     * @param ?int $length
70     * @return string
71     *
72     * @throws TypeError
73     */
74    public static function safeSubstr(
75        #[\SensitiveParameter]
76        string $str,
77        int $start = 0,
78        $length = null
79    ): string {
80        if ($length === 0) {
81            return '';
82        }
83        if (\function_exists('mb_substr')) {
84            return \mb_substr($str, $start, $length, '8bit');
85        }
86        // Unlike mb_substr(), substr() doesn't accept NULL for length
87        if ($length !== null) {
88            return \substr($str, $start, $length);
89        } else {
90            return \substr($str, $start);
91        }
92    }
93}
94