PHP Classes
elePHPant
Icontem

File: vendor/paragonie/random_compat/lib/random_int.php

Recommend this page to a friend!
  Classes of Renato De Oliveira Lucena  >  PHP Pokemon Script  >  vendor/paragonie/random_compat/lib/random_int.php  >  Download  
File: vendor/paragonie/random_compat/lib/random_int.php
Role: Example script
Content type: text/plain
Description: Example script
Class: PHP Pokemon Script
Provides an API to manage a database of Pokemons
Author: By
Last change:
Date: 1 year ago
Size: 6,255 bytes
 

Contents

Class file image Download
<?php

if (!is_callable('random_int')) {
   
/**
     * Random_* Compatibility Library
     * for using the new PHP 7 random_* API in PHP 5 projects
     *
     * The MIT License (MIT)
     *
     * Copyright (c) 2015 - 2017 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.
     */

    /**
     * Fetch a random integer between $min and $max inclusive
     *
     * @param int $min
     * @param int $max
     *
     * @throws Exception
     *
     * @return int
     */
   
function random_int($min, $max)
    {
       
/**
         * Type and input logic checks
         *
         * If you pass it a float in the range (~PHP_INT_MAX, PHP_INT_MAX)
         * (non-inclusive), it will sanely cast it to an int. If you it's equal to
         * ~PHP_INT_MAX or PHP_INT_MAX, we let it fail as not an integer. Floats
         * lose precision, so the <= and => operators might accidentally let a float
         * through.
         */

       
try {
           
$min = RandomCompat_intval($min);
        } catch (
TypeError $ex) {
            throw new
TypeError(
               
'random_int(): $min must be an integer'
           
);
        }

        try {
           
$max = RandomCompat_intval($max);
        } catch (
TypeError $ex) {
            throw new
TypeError(
               
'random_int(): $max must be an integer'
           
);
        }

       
/**
         * Now that we've verified our weak typing system has given us an integer,
         * let's validate the logic then we can move forward with generating random
         * integers along a given range.
         */
       
if ($min > $max) {
            throw new
Error(
               
'Minimum value must be less than or equal to the maximum value'
           
);
        }

        if (
$max === $min) {
            return
$min;
        }

       
/**
         * Initialize variables to 0
         *
         * We want to store:
         * $bytes => the number of random bytes we need
         * $mask => an integer bitmask (for use with the &) operator
         * so we can minimize the number of discards
         */
       
$attempts = $bits = $bytes = $mask = $valueShift = 0;

       
/**
         * At this point, $range is a positive number greater than 0. It might
         * overflow, however, if $max - $min > PHP_INT_MAX. PHP will cast it to
         * a float and we will lose some precision.
         */
       
$range = $max - $min;

       
/**
         * Test for integer overflow:
         */
       
if (!is_int($range)) {

           
/**
             * Still safely calculate wider ranges.
             * Provided by @CodesInChaos, @oittaa
             *
             * @ref https://gist.github.com/CodesInChaos/03f9ea0b58e8b2b8d435
             *
             * We use ~0 as a mask in this case because it generates all 1s
             *
             * @ref https://eval.in/400356 (32-bit)
             * @ref http://3v4l.org/XX9r5 (64-bit)
             */
           
$bytes = PHP_INT_SIZE;
           
$mask = ~0;

        } else {

           
/**
             * $bits is effectively ceil(log($range, 2)) without dealing with
             * type juggling
             */
           
while ($range > 0) {
                if (
$bits % 8 === 0) {
                    ++
$bytes;
                }
                ++
$bits;
               
$range >>= 1;
               
$mask = $mask << 1 | 1;
            }
           
$valueShift = $min;
        }

       
$val = 0;
       
/**
         * Now that we have our parameters set up, let's begin generating
         * random integers until one falls between $min and $max
         */
       
do {
           
/**
             * The rejection probability is at most 0.5, so this corresponds
             * to a failure probability of 2^-128 for a working RNG
             */
           
if ($attempts > 128) {
                throw new
Exception(
                   
'random_int: RNG is broken - too many rejections'
               
);
            }

           
/**
             * Let's grab the necessary number of random bytes
             */
           
$randomByteString = random_bytes($bytes);

           
/**
             * Let's turn $randomByteString into an integer
             *
             * This uses bitwise operators (<< and |) to build an integer
             * out of the values extracted from ord()
             *
             * Example: [9F] | [6D] | [32] | [0C] =>
             * 159 + 27904 + 3276800 + 201326592 =>
             * 204631455
             */
           
$val &= 0;
            for (
$i = 0; $i < $bytes; ++$i) {
               
$val |= ord($randomByteString[$i]) << ($i * 8);
            }

           
/**
             * Apply mask
             */
           
$val &= $mask;
           
$val += $valueShift;

            ++
$attempts;
           
/**
             * If $val overflows to a floating point number,
             * ... or is larger than $max,
             * ... or smaller than $min,
             * then try again.
             */
       
} while (!is_int($val) || $val > $max || $val < $min);

        return (int)
$val;
    }
}