LCOV - code coverage report
Current view: top level - lib/Support - RandomNumberGenerator.cpp (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 23 27 85.2 %
Date: 2017-09-14 15:23:50 Functions: 5 5 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===-- RandomNumberGenerator.cpp - Implement RNG class -------------------===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // This file implements deterministic random number generation (RNG).
      11             : // The current implementation is NOT cryptographically secure as it uses
      12             : // the C++11 <random> facilities.
      13             : //
      14             : //===----------------------------------------------------------------------===//
      15             : 
      16             : #include "llvm/Support/RandomNumberGenerator.h"
      17             : #include "llvm/Support/CommandLine.h"
      18             : #include "llvm/Support/Debug.h"
      19             : #include "llvm/Support/raw_ostream.h"
      20             : #ifdef LLVM_ON_WIN32
      21             : #include "Windows/WindowsSupport.h"
      22             : #else
      23             : #include "Unix/Unix.h"
      24             : #endif
      25             : 
      26             : using namespace llvm;
      27             : 
      28             : #define DEBUG_TYPE "rng"
      29             : 
      30             : // Tracking BUG: 19665
      31             : // http://llvm.org/bugs/show_bug.cgi?id=19665
      32             : //
      33             : // Do not change to cl::opt<uint64_t> since this silently breaks argument parsing.
      34             : static cl::opt<unsigned long long>
      35      289320 : Seed("rng-seed", cl::value_desc("seed"),
      36      361650 :      cl::desc("Seed for the random number generator"), cl::init(0));
      37             : 
      38           4 : RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) {
      39             :   DEBUG(
      40             :     if (Seed == 0)
      41             :       dbgs() << "Warning! Using unseeded random number generator.\n"
      42             :   );
      43             : 
      44             :   // Combine seed and salts using std::seed_seq.
      45             :   // Data: Seed-low, Seed-high, Salt
      46             :   // Note: std::seed_seq can only store 32-bit values, even though we
      47             :   // are using a 64-bit RNG. This isn't a problem since the Mersenne
      48             :   // twister constructor copies these correctly into its initial state.
      49           4 :   std::vector<uint32_t> Data;
      50           2 :   Data.resize(2 + Salt.size());
      51           2 :   Data[0] = Seed;
      52           2 :   Data[1] = Seed >> 32;
      53             : 
      54           8 :   std::copy(Salt.begin(), Salt.end(), Data.begin() + 2);
      55             : 
      56           8 :   std::seed_seq SeedSeq(Data.begin(), Data.end());
      57           2 :   Generator.seed(SeedSeq);
      58           2 : }
      59             : 
      60          20 : RandomNumberGenerator::result_type RandomNumberGenerator::operator()() {
      61          20 :   return Generator();
      62             : }
      63             : 
      64             : // Get random vector of specified size
      65          37 : std::error_code llvm::getRandomBytes(void *Buffer, size_t Size) {
      66             : #ifdef LLVM_ON_WIN32
      67             :   HCRYPTPROV hProvider;
      68             :   if (CryptAcquireContext(&hProvider, 0, 0, PROV_RSA_FULL,
      69             :                            CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
      70             :     ScopedCryptContext ScopedHandle(hProvider);
      71             :     if (CryptGenRandom(hProvider, Size, static_cast<BYTE *>(Buffer)))
      72             :       return std::error_code();
      73             :   }
      74             :   return std::error_code(GetLastError(), std::system_category());
      75             : #else
      76          37 :   int Fd = open("/dev/urandom", O_RDONLY);
      77          37 :   if (Fd != -1) {
      78          37 :     std::error_code Ret;
      79          37 :     ssize_t BytesRead = read(Fd, Buffer, Size);
      80          37 :     if (BytesRead == -1)
      81           0 :       Ret = std::error_code(errno, std::system_category());
      82          37 :     else if (BytesRead != static_cast<ssize_t>(Size))
      83           0 :       Ret = std::error_code(EIO, std::system_category());
      84          37 :     if (close(Fd) == -1)
      85           0 :       Ret = std::error_code(errno, std::system_category());
      86             : 
      87          37 :     return Ret;
      88             :   }
      89           0 :   return std::error_code(errno, std::system_category());
      90             : #endif
      91      216990 : }

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