RandomNumberGenerator.cpp

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1//===-- RandomNumberGenerator.cpp - Implement RNG class -------------------===//

2//

3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

4// See https://llvm.org/LICENSE.txt for license information.

5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

6//

7//===----------------------------------------------------------------------===//

8//

9// This file implements deterministic random number generation (RNG).

10// The current implementation is NOT cryptographically secure as it uses

11// the C++11 <random> facilities.

12//

13//===----------------------------------------------------------------------===//

14

15#include "llvm/Support/RandomNumberGenerator.h"

16

17#include "DebugOptions.h"

18

19#include "llvm/Support/CommandLine.h"

20#include "llvm/Support/Debug.h"

21#include "llvm/Support/Error.h"

22#include "llvm/Support/ManagedStatic.h"

23#include "llvm/Support/raw_ostream.h"

24#ifdef _WIN32

25#include "llvm/Support/Windows/WindowsSupport.h"

26#else

27#include "Unix/Unix.h"

28#endif

29

30using namespace llvm;

31

32 #define DEBUG_TYPE "rng"

33namespace {

34struct CreateSeed {

35 static void *call() {

36 return new cl::opt<uint64_t>(

37 "rng-seed", cl::value_desc("seed"), cl::Hidden,

38 cl::desc("Seed for the random number generator"), cl::init(0));

39 }

40};

41} // namespace

42 static ManagedStatic<cl::opt<uint64_t>, CreateSeed> Seed;

43 void llvm::initRandomSeedOptions() { *Seed; }

44

45RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) {

46 LLVM_DEBUG(if (*Seed == 0) dbgs()

47 << "Warning! Using unseeded random number generator.\n");

48

49 // Combine seed and salts using std::seed_seq.

50 // Data: Seed-low, Seed-high, Salt

51 // Note: std::seed_seq can only store 32-bit values, even though we

52 // are using a 64-bit RNG. This isn't a problem since the Mersenne

53 // twister constructor copies these correctly into its initial state.

54 std::vector<uint32_t> Data;

55 Data.resize(2 + Salt.size());

56 Data[0] = *Seed;

57 Data[1] = *Seed >> 32;

58

59 llvm::copy(Salt, Data.begin() + 2);

60

61 std::seed_seq SeedSeq(Data.begin(), Data.end());

62 Generator.seed(SeedSeq);

63}

64

65 RandomNumberGenerator::result_type RandomNumberGenerator::operator()() {

66 return Generator();

67}

68

69// Get random vector of specified size

70 std::error_code llvm::getRandomBytes(void *Buffer, size_t Size) {

71#ifdef _WIN32

72 HCRYPTPROV hProvider;

73 if (CryptAcquireContext(&hProvider, 0, 0, PROV_RSA_FULL,

74 CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {

75 ScopedCryptContext ScopedHandle(hProvider);

76 if (CryptGenRandom(hProvider, Size, static_cast<BYTE *>(Buffer)))

77 return std::error_code();

78 }

79 return std::error_code(GetLastError(), std::system_category());

80#else

81 int Fd = open("/dev/urandom", O_RDONLY);

82 if (Fd != -1) {

83 std::error_code Ret;

84 ssize_t BytesRead = read(Fd, Buffer, Size);

85 if (BytesRead == -1)

86 Ret = errnoAsErrorCode();

87 else if (BytesRead != static_cast<ssize_t>(Size))

88 Ret = std::error_code(EIO, std::system_category());

89 if (close(Fd) == -1)

90 Ret = errnoAsErrorCode();

91

92 return Ret;

93 }

94 return errnoAsErrorCode();

95#endif

96}

CommandLine.h

DebugOptions.h

InlinePriorityMode::Size

@ Size

Definition InlineOrder.cpp:25

ManagedStatic.h

Seed

static ManagedStatic< cl::opt< uint64_t >, CreateSeed > Seed

Definition RandomNumberGenerator.cpp:42

RandomNumberGenerator.h

Debug.h

LLVM_DEBUG

#define LLVM_DEBUG(...)

Definition Debug.h:114

Unix.h

WindowsSupport.h

llvm::ManagedStatic

ManagedStatic - This transparently changes the behavior of global statics to be lazily constructed on...

Definition ManagedStatic.h:85

llvm::RandomNumberGenerator::result_type

generator_type::result_type result_type

Definition RandomNumberGenerator.h:41

llvm::RandomNumberGenerator::operator()

LLVM_ABI result_type operator()()

Returns a random number in the range [0, Max).

Definition RandomNumberGenerator.cpp:65

llvm::ScopedHandle

Definition WindowsSupport.h:79

llvm::StringRef

StringRef - Represent a constant reference to a string, i.e.

Definition StringRef.h:55

llvm::StringRef::size

constexpr size_t size() const

size - Get the string size.

Definition StringRef.h:146

llvm::cl::opt

Definition CommandLine.h:1455

Error.h

llvm::cl::Hidden

@ Hidden

Definition CommandLine.h:139

llvm::cl::init

initializer< Ty > init(const Ty &Val)

Definition CommandLine.h:445

llvm

This is an optimization pass for GlobalISel generic memory operations.

Definition AddressRanges.h:18

llvm::ScopedCryptContext

ScopedHandle< CryptContextTraits > ScopedCryptContext

Definition WindowsSupport.h:184

llvm::dbgs

LLVM_ABI raw_ostream & dbgs()

dbgs() - This returns a reference to a raw_ostream for debugging messages.

Definition Debug.cpp:207

llvm::Data

FunctionAddr VTableAddr uintptr_t uintptr_t Data

Definition InstrProf.h:189

llvm::initRandomSeedOptions

void initRandomSeedOptions()

Definition RandomNumberGenerator.cpp:43

llvm::getRandomBytes

LLVM_ABI std::error_code getRandomBytes(void *Buffer, size_t Size)

Definition RandomNumberGenerator.cpp:70

llvm::copy

OutputIt copy(R &&Range, OutputIt Out)

Definition STLExtras.h:1835

llvm::errnoAsErrorCode

std::error_code errnoAsErrorCode()

Helper to get errno as an std::error_code.

Definition Error.h:1240

raw_ostream.h

llvm::cl::desc

Definition CommandLine.h:411

llvm::cl::value_desc

Definition CommandLine.h:420

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