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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
89 lines
3.0 KiB
C++
89 lines
3.0 KiB
C++
//===-- RandomNumberGenerator.cpp - Implement RNG class -------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements deterministic random number generation (RNG).
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// The current implementation is NOT cryptographically secure as it uses
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// the C++11 <random> facilities.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/RandomNumberGenerator.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#ifdef _WIN32
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#include "Windows/WindowsSupport.h"
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#else
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#include "Unix/Unix.h"
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#endif
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using namespace llvm;
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#define DEBUG_TYPE "rng"
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// Tracking BUG: 19665
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// http://llvm.org/bugs/show_bug.cgi?id=19665
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//
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// Do not change to cl::opt<uint64_t> since this silently breaks argument parsing.
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static cl::opt<unsigned long long>
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Seed("rng-seed", cl::value_desc("seed"), cl::Hidden,
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cl::desc("Seed for the random number generator"), cl::init(0));
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RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) {
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LLVM_DEBUG(if (Seed == 0) dbgs()
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<< "Warning! Using unseeded random number generator.\n");
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// Combine seed and salts using std::seed_seq.
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// Data: Seed-low, Seed-high, Salt
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// Note: std::seed_seq can only store 32-bit values, even though we
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// are using a 64-bit RNG. This isn't a problem since the Mersenne
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// twister constructor copies these correctly into its initial state.
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std::vector<uint32_t> Data;
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Data.resize(2 + Salt.size());
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Data[0] = Seed;
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Data[1] = Seed >> 32;
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llvm::copy(Salt, Data.begin() + 2);
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std::seed_seq SeedSeq(Data.begin(), Data.end());
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Generator.seed(SeedSeq);
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}
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RandomNumberGenerator::result_type RandomNumberGenerator::operator()() {
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return Generator();
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}
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// Get random vector of specified size
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std::error_code llvm::getRandomBytes(void *Buffer, size_t Size) {
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#ifdef _WIN32
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HCRYPTPROV hProvider;
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if (CryptAcquireContext(&hProvider, 0, 0, PROV_RSA_FULL,
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CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
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ScopedCryptContext ScopedHandle(hProvider);
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if (CryptGenRandom(hProvider, Size, static_cast<BYTE *>(Buffer)))
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return std::error_code();
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}
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return std::error_code(GetLastError(), std::system_category());
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#else
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int Fd = open("/dev/urandom", O_RDONLY);
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if (Fd != -1) {
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std::error_code Ret;
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ssize_t BytesRead = read(Fd, Buffer, Size);
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if (BytesRead == -1)
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Ret = std::error_code(errno, std::system_category());
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else if (BytesRead != static_cast<ssize_t>(Size))
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Ret = std::error_code(EIO, std::system_category());
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if (close(Fd) == -1)
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Ret = std::error_code(errno, std::system_category());
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return Ret;
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}
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return std::error_code(errno, std::system_category());
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#endif
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}
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