mirror of
https://github.com/SerenityOS/serenity
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82 lines
1.8 KiB
C++
82 lines
1.8 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Platform.h>
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#include <AK/Span.h>
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#include <AK/StdLibExtras.h>
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#include <AK/Types.h>
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#include <stdlib.h>
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#if defined(__unix__)
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# include <unistd.h>
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#endif
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namespace AK {
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inline void fill_with_random([[maybe_unused]] Bytes bytes)
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{
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#if defined(AK_OS_SERENITY) || defined(AK_OS_ANDROID) || defined(AK_OS_BSD_GENERIC) || defined(AK_OS_HAIKU) || AK_LIBC_GLIBC_PREREQ(2, 36)
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arc4random_buf(bytes.data(), bytes.size());
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#elif defined(OSS_FUZZ)
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#else
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auto fill_with_random_fallback = [&]() {
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for (auto& byte : bytes)
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byte = rand();
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};
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# if defined(__unix__)
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// The maximum permitted value for the getentropy length argument.
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static constexpr size_t getentropy_length_limit = 256;
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auto iterations = bytes.size() / getentropy_length_limit;
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for (size_t i = 0; i < iterations; ++i) {
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if (getentropy(bytes.data(), getentropy_length_limit) != 0) {
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fill_with_random_fallback();
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return;
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}
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bytes = bytes.slice(getentropy_length_limit);
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}
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if (bytes.is_empty() || getentropy(bytes.data(), bytes.size()) == 0)
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return;
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# endif
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fill_with_random_fallback();
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#endif
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}
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template<typename T>
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inline T get_random()
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{
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T t;
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fill_with_random({ &t, sizeof(T) });
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return t;
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}
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u32 get_random_uniform(u32 max_bounds);
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template<typename Collection>
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inline void shuffle(Collection& collection)
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{
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// Fisher-Yates shuffle
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for (size_t i = collection.size() - 1; i >= 1; --i) {
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size_t j = get_random_uniform(i + 1);
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AK::swap(collection[i], collection[j]);
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}
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}
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}
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#if USING_AK_GLOBALLY
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using AK::fill_with_random;
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using AK::get_random;
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using AK::get_random_uniform;
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using AK::shuffle;
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#endif
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