79 lines
2.6 KiB
C++
79 lines
2.6 KiB
C++
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_RAND_UTIL_H_
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#define BASE_RAND_UTIL_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <algorithm>
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#include <string>
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#include "base/base_export.h"
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#include "build/build_config.h"
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namespace base {
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// Returns a random number in range [0, UINT64_MAX]. Thread-safe.
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BASE_EXPORT uint64_t RandUint64();
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// Returns a random number between min and max (inclusive). Thread-safe.
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BASE_EXPORT int RandInt(int min, int max);
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// Returns a random number in range [0, range). Thread-safe.
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BASE_EXPORT uint64_t RandGenerator(uint64_t range);
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// Returns a random double in range [0, 1). Thread-safe.
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BASE_EXPORT double RandDouble();
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// Given input |bits|, convert with maximum precision to a double in
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// the range [0, 1). Thread-safe.
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BASE_EXPORT double BitsToOpenEndedUnitInterval(uint64_t bits);
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// Fills |output_length| bytes of |output| with random data. Thread-safe.
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//
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// Although implementations are required to use a cryptographically secure
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// random number source, code outside of base/ that relies on this should use
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// crypto::RandBytes instead to ensure the requirement is easily discoverable.
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BASE_EXPORT void RandBytes(void* output, size_t output_length);
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// Fills a string of length |length| with random data and returns it.
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// |length| should be nonzero. Thread-safe.
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//
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// Note that this is a variation of |RandBytes| with a different return type.
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// The returned string is likely not ASCII/UTF-8. Use with care.
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//
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// Although implementations are required to use a cryptographically secure
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// random number source, code outside of base/ that relies on this should use
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// crypto::RandBytes instead to ensure the requirement is easily discoverable.
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BASE_EXPORT std::string RandBytesAsString(size_t length);
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// An STL UniformRandomBitGenerator backed by RandUint64.
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// TODO(tzik): Consider replacing this with a faster implementation.
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class RandomBitGenerator {
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public:
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using result_type = uint64_t;
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static constexpr result_type min() { return 0; }
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static constexpr result_type max() { return UINT64_MAX; }
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result_type operator()() const { return RandUint64(); }
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RandomBitGenerator() = default;
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~RandomBitGenerator() = default;
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};
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// Shuffles [first, last) randomly. Thread-safe.
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template <typename Itr>
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void RandomShuffle(Itr first, Itr last) {
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std::shuffle(first, last, RandomBitGenerator());
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}
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#if defined(OS_POSIX)
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BASE_EXPORT int GetUrandomFD();
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#endif
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} // namespace base
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#endif // BASE_RAND_UTIL_H_
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