//===-- RandomNumberGenerator.cpp - Implement RNG class -------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file implements deterministic random number generation (RNG). // The current implementation is NOT cryptographically secure as it uses // the C++11 facilities. // //===----------------------------------------------------------------------===// #include "llvm/Support/RandomNumberGenerator.h" #include "DebugOptions.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/Error.h" #include "llvm/Support/ManagedStatic.h" #include "llvm/Support/raw_ostream.h" #ifdef _WIN32 #include "llvm/Support/Windows/WindowsSupport.h" #else #include "Unix/Unix.h" #endif using namespace llvm; #define DEBUG_TYPE "rng" namespace { struct CreateSeed { static void *call() { return new cl::opt( "rng-seed", cl::value_desc("seed"), cl::Hidden, cl::desc("Seed for the random number generator"), cl::init(0)); } }; } // namespace static ManagedStatic, CreateSeed> Seed; void llvm::initRandomSeedOptions() { *Seed; } RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) { LLVM_DEBUG(if (*Seed == 0) dbgs() << "Warning! Using unseeded random number generator.\n"); // Combine seed and salts using std::seed_seq. // Data: Seed-low, Seed-high, Salt // Note: std::seed_seq can only store 32-bit values, even though we // are using a 64-bit RNG. This isn't a problem since the Mersenne // twister constructor copies these correctly into its initial state. std::vector Data; Data.resize(2 + Salt.size()); Data[0] = *Seed; Data[1] = *Seed >> 32; llvm::copy(Salt, Data.begin() + 2); std::seed_seq SeedSeq(Data.begin(), Data.end()); Generator.seed(SeedSeq); } RandomNumberGenerator::result_type RandomNumberGenerator::operator()() { return Generator(); } // Get random vector of specified size std::error_code llvm::getRandomBytes(void *Buffer, size_t Size) { #ifdef _WIN32 HCRYPTPROV hProvider; if (CryptAcquireContext(&hProvider, 0, 0, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) { ScopedCryptContext ScopedHandle(hProvider); if (CryptGenRandom(hProvider, Size, static_cast(Buffer))) return std::error_code(); } return std::error_code(GetLastError(), std::system_category()); #else int Fd = open("/dev/urandom", O_RDONLY); if (Fd != -1) { std::error_code Ret; ssize_t BytesRead = read(Fd, Buffer, Size); if (BytesRead == -1) Ret = errnoAsErrorCode(); else if (BytesRead != static_cast(Size)) Ret = std::error_code(EIO, std::system_category()); if (close(Fd) == -1) Ret = errnoAsErrorCode(); return Ret; } return errnoAsErrorCode(); #endif }