Imported Upstream version 5.18.0.179

Former-commit-id: 67aa10e65b237e1c4537630979ee99ebe1374215

external/llvm/lib/Support/RandomNumberGenerator.cpp

@@ -0,0 +1,91 @@
+//===-- 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
+}