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/raw_ostream.h" |
22 | #ifdef _WIN32 |
23 | #include "llvm/Support/Windows/WindowsSupport.h" |
24 | #else |
25 | #include "Unix/Unix.h" |
26 | #endif |
27 | |
28 | using namespace llvm; |
29 | |
30 | #define DEBUG_TYPE "rng" |
31 | namespace { |
32 | struct CreateSeed { |
33 | static void *call() { |
34 | return new cl::opt<uint64_t>( |
35 | "rng-seed" , cl::value_desc("seed" ), cl::Hidden, |
36 | cl::desc("Seed for the random number generator" ), cl::init(Val: 0)); |
37 | } |
38 | }; |
39 | } // namespace |
40 | static ManagedStatic<cl::opt<uint64_t>, CreateSeed> Seed; |
41 | void llvm::initRandomSeedOptions() { *Seed; } |
42 | |
43 | RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) { |
44 | LLVM_DEBUG(if (*Seed == 0) dbgs() |
45 | << "Warning! Using unseeded random number generator.\n" ); |
46 | |
47 | // Combine seed and salts using std::seed_seq. |
48 | // Data: Seed-low, Seed-high, Salt |
49 | // Note: std::seed_seq can only store 32-bit values, even though we |
50 | // are using a 64-bit RNG. This isn't a problem since the Mersenne |
51 | // twister constructor copies these correctly into its initial state. |
52 | std::vector<uint32_t> Data; |
53 | Data.resize(new_size: 2 + Salt.size()); |
54 | Data[0] = *Seed; |
55 | Data[1] = *Seed >> 32; |
56 | |
57 | llvm::copy(Range&: Salt, Out: Data.begin() + 2); |
58 | |
59 | std::seed_seq SeedSeq(Data.begin(), Data.end()); |
60 | Generator.seed(q&: SeedSeq); |
61 | } |
62 | |
63 | RandomNumberGenerator::result_type RandomNumberGenerator::operator()() { |
64 | return Generator(); |
65 | } |
66 | |
67 | // Get random vector of specified size |
68 | std::error_code llvm::getRandomBytes(void *Buffer, size_t Size) { |
69 | #ifdef _WIN32 |
70 | HCRYPTPROV hProvider; |
71 | if (CryptAcquireContext(&hProvider, 0, 0, PROV_RSA_FULL, |
72 | CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) { |
73 | ScopedCryptContext ScopedHandle(hProvider); |
74 | if (CryptGenRandom(hProvider, Size, static_cast<BYTE *>(Buffer))) |
75 | return std::error_code(); |
76 | } |
77 | return std::error_code(GetLastError(), std::system_category()); |
78 | #else |
79 | int Fd = open(file: "/dev/urandom" , O_RDONLY); |
80 | if (Fd != -1) { |
81 | std::error_code Ret; |
82 | ssize_t BytesRead = read(fd: Fd, buf: Buffer, nbytes: Size); |
83 | if (BytesRead == -1) |
84 | Ret = std::error_code(errno, std::system_category()); |
85 | else if (BytesRead != static_cast<ssize_t>(Size)) |
86 | Ret = std::error_code(EIO, std::system_category()); |
87 | if (close(fd: Fd) == -1) |
88 | Ret = std::error_code(errno, std::system_category()); |
89 | |
90 | return Ret; |
91 | } |
92 | return std::error_code(errno, std::system_category()); |
93 | #endif |
94 | } |
95 | |