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llvm-mirror/lib/Support/RandomNumberGenerator.cpp
Zachary Turner dec9bd8187 Mark all library options as hidden.
These command line options are not intended for public use, and often
don't even make sense in the context of a particular tool anyway. About
90% of them are already hidden, but when people add new options they
forget to hide them, so if you were to make a brand new tool today, link
against one of LLVM's libraries, and run tool -help you would get a
bunch of junk that doesn't make sense for the tool you're writing.

This patch hides these options. The real solution is to not have
libraries defining command line options, but that's a much larger effort
and not something I'm prepared to take on.

Differential Revision: https://reviews.llvm.org/D40674

llvm-svn: 319505
2017-12-01 00:53:10 +00:00

92 lines
3.0 KiB
C++

//===-- RandomNumberGenerator.cpp - Implement RNG class -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements deterministic random number generation (RNG).
// The current implementation is NOT cryptographically secure as it uses
// the C++11 <random> facilities.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/RandomNumberGenerator.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#ifdef LLVM_ON_WIN32
#include "Windows/WindowsSupport.h"
#else
#include "Unix/Unix.h"
#endif
using namespace llvm;
#define DEBUG_TYPE "rng"
// Tracking BUG: 19665
// http://llvm.org/bugs/show_bug.cgi?id=19665
//
// Do not change to cl::opt<uint64_t> since this silently breaks argument parsing.
static cl::opt<unsigned long long>
Seed("rng-seed", cl::value_desc("seed"), cl::Hidden,
cl::desc("Seed for the random number generator"), cl::init(0));
RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) {
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<uint32_t> Data;
Data.resize(2 + Salt.size());
Data[0] = Seed;
Data[1] = Seed >> 32;
std::copy(Salt.begin(), Salt.end(), 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 LLVM_ON_WIN32
HCRYPTPROV hProvider;
if (CryptAcquireContext(&hProvider, 0, 0, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
ScopedCryptContext ScopedHandle(hProvider);
if (CryptGenRandom(hProvider, Size, static_cast<BYTE *>(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 = std::error_code(errno, std::system_category());
else if (BytesRead != static_cast<ssize_t>(Size))
Ret = std::error_code(EIO, std::system_category());
if (close(Fd) == -1)
Ret = std::error_code(errno, std::system_category());
return Ret;
}
return std::error_code(errno, std::system_category());
#endif
}