// Copyright (c) 2012 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef BUTIL_RAND_UTIL_H_ #define BUTIL_RAND_UTIL_H_ #include <string> #include "butil/base_export.h" #include "butil/basictypes.h" namespace butil { // -------------------------------------------------------------------------- // NOTE(gejun): Functions in this header read from /dev/urandom in posix // systems and are not proper for performance critical situations. // For fast random numbers, check fast_rand.h // -------------------------------------------------------------------------- // Returns a random number in range [0, kuint64max]. Thread-safe. BUTIL_EXPORT uint64_t RandUint64(); // Returns a random number between min and max (inclusive). Thread-safe. BUTIL_EXPORT int RandInt(int min, int max); // Returns a random number in range [0, range). Thread-safe. // // Note that this can be used as an adapter for std::random_shuffle(): // Given a pre-populated |std::vector<int> myvector|, shuffle it as // std::random_shuffle(myvector.begin(), myvector.end(), butil::RandGenerator); BUTIL_EXPORT uint64_t RandGenerator(uint64_t range); // Returns a random double in range [0, 1). Thread-safe. BUTIL_EXPORT double RandDouble(); // Given input |bits|, convert with maximum precision to a double in // the range [0, 1). Thread-safe. BUTIL_EXPORT double BitsToOpenEndedUnitInterval(uint64_t bits); // Fills |output_length| bytes of |output| with random data. // // WARNING: // Do not use for security-sensitive purposes. // See crypto/ for cryptographically secure random number generation APIs. BUTIL_EXPORT void RandBytes(void* output, size_t output_length); // Fills a string of length |length| with random data and returns it. // |length| should be nonzero. // // Note that this is a variation of |RandBytes| with a different return type. // The returned string is likely not ASCII/UTF-8. Use with care. // // WARNING: // Do not use for security-sensitive purposes. // See crypto/ for cryptographically secure random number generation APIs. BUTIL_EXPORT std::string RandBytesAsString(size_t length); #if defined(OS_POSIX) BUTIL_EXPORT int GetUrandomFD(); #endif } // namespace butil #endif // BUTIL_RAND_UTIL_H_