Add generateRandomUuidString C++ helper (#54089)

Summary:
Pull Request resolved: #54089

Changelog: [Internal]

Adds a minimal standards-compliant UUID v4 generator to `react/utils` for use elsewhere in React Native. We don't need UUID parsing, support for UUID versions other than 4, a UUID value type, or extremely high performance - which makes inlining this simple, portable implementation directly in our codebase acceptable.

Reviewed By: robhogan

Differential Revision: D84149720

fbshipit-source-id: 399d88f4adaff3be4fef5dd1abab3c8552ca1a75

Author: motiz88

packages/react-native/ReactCommon/react/utils/Uuid.cpp

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "Uuid.h"
+
+#include <array>
+#include <iomanip>
+#include <random>
+#include <sstream>
+
+namespace {
+
+std::mt19937& getThreadLocalEngine() {
+  static thread_local std::random_device device;
+  static thread_local std::mt19937 engine(device());
+  return engine;
+}
+
+uint64_t randomUInt64(uint64_t max = std::numeric_limits<uint64_t>::max()) {
+  std::uniform_int_distribution<uint64_t> distribution(0, max);
+  return distribution(getThreadLocalEngine());
+}
+
+} // namespace
+
+namespace facebook::react {
+
+std::string generateRandomUuidString() {
+  static constexpr uint8_t kUuidLength = 16;
+  // see: https://tools.ietf.org/html/rfc4122#section-4.1.2 for reference
+  static constexpr uint8_t kTimeLowSegBufEnd = sizeof(uint32_t);
+  static constexpr uint8_t kTimeMidSegBufEnd =
+      kTimeLowSegBufEnd + sizeof(uint16_t);
+  static constexpr uint8_t kTimeHiAndVersionSegBufEnd =
+      kTimeMidSegBufEnd + sizeof(uint16_t);
+  static constexpr uint8_t kClockHiLoSegBufEnd =
+      kTimeHiAndVersionSegBufEnd + sizeof(uint16_t);
+  static constexpr uint8_t kNodeSegHiBufEnd =
+      kClockHiLoSegBufEnd + sizeof(uint16_t);
+
+  std::array<uint8_t, kUuidLength> uuidBytes;
+
+  *(uint64_t*)uuidBytes.data() = randomUInt64();
+  *(uint64_t*)(uuidBytes.data() + sizeof(uint64_t)) = randomUInt64();
+
+  // Conforming to RFC 4122: https://www.cryptosys.net/pki/uuid-rfc4122.html
+  uuidBytes[7] &= 0x0f;
+  uuidBytes[7] |= 0x40;
+  uuidBytes[9] &= 0x3f;
+  uuidBytes[9] |= 0x80;
+
+  std::stringstream ss;
+
+  ss << std::setfill('0') << std::setw(8) << std::right << std::hex
+     << *(uint32_t*)uuidBytes.data() << "-" << std::setw(4)
+     << *(uint16_t*)(uuidBytes.data() + kTimeLowSegBufEnd) << "-"
+     << *(uint16_t*)(uuidBytes.data() + kTimeMidSegBufEnd) << "-"
+     << *(uint16_t*)(uuidBytes.data() + kTimeHiAndVersionSegBufEnd) << "-"
+     << std::setw(8) << *(uint32_t*)(uuidBytes.data() + kNodeSegHiBufEnd)
+     << std::setw(4) << *(uint16_t*)(uuidBytes.data() + kClockHiLoSegBufEnd);
+
+  return ss.str();
+}
+
+} // namespace facebook::react

packages/react-native/ReactCommon/react/utils/Uuid.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <string>
+
+namespace facebook::react {
+
+/**
+ * Generates a random UUID version 4 string in the format
+ * xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx (lowercase).
+ */
+std::string generateRandomUuidString();
+
+} // namespace facebook::react

packages/react-native/ReactCommon/react/utils/tests/UuidTest.cpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <react/utils/Uuid.h>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using namespace ::testing;
+
+namespace facebook::react {
+
+TEST(UuidTest, TestGenerateRandomUuidString) {
+  static constexpr auto kUuidV4Regex =
+      "[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}";
+
+  std::string uuid1 = generateRandomUuidString();
+  std::string uuid2 = generateRandomUuidString();
+  EXPECT_THAT(uuid1, MatchesRegex(kUuidV4Regex));
+  EXPECT_THAT(uuid2, MatchesRegex(kUuidV4Regex));
+  EXPECT_NE(uuid1, uuid2);
+}
+
+} // namespace facebook::react