diff --git a/TEST_MAPPING b/TEST_MAPPING
index 716378b..66d0c92 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -28,6 +28,13 @@
       "name": "memunreachable_test"
     },
     {
+      "name": "memunreachable_unit_test"
+    },
+    {
+      "name": "memunreachable_unit_test",
+      "host": true
+    },
+    {
       "name": "memunreachable_binder_test"
     },
     {
diff --git a/base/Android.bp b/base/Android.bp
index 340f814..58d3a50 100644
--- a/base/Android.bp
+++ b/base/Android.bp
@@ -131,6 +131,7 @@
         "cmsg_test.cpp",
         "endian_test.cpp",
         "errors_test.cpp",
+        "expected_test.cpp",
         "file_test.cpp",
         "logging_test.cpp",
         "macros_test.cpp",
diff --git a/base/expected_test.cpp b/base/expected_test.cpp
new file mode 100644
index 0000000..490ced4
--- /dev/null
+++ b/base/expected_test.cpp
@@ -0,0 +1,745 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "android-base/expected.h"
+
+#include <cstdio>
+#include <memory>
+#include <string>
+
+#include <gtest/gtest.h>
+
+using android::base::expected;
+using android::base::unexpected;
+
+typedef expected<int, int> exp_int;
+typedef expected<double, double> exp_double;
+typedef expected<std::string, std::string> exp_string;
+typedef expected<std::pair<std::string, int>, int> exp_pair;
+
+struct T {
+  int a;
+  int b;
+  T() = default;
+  T(int a, int b) noexcept : a(a), b(b) {}
+};
+bool operator==(const T& x, const T& y) {
+  return x.a == y.a && x.b == y.b;
+}
+bool operator!=(const T& x, const T& y) {
+  return x.a != y.a || x.b != y.b;
+}
+
+struct E {
+    std::string message;
+    int cause;
+    E(const std::string& message, int cause) : message(message), cause(cause) {}
+};
+
+typedef expected<T,E> exp_complex;
+
+TEST(Expected, testDefaultConstructible) {
+  exp_int e;
+  EXPECT_TRUE(e.has_value());
+  EXPECT_EQ(0, e.value());
+
+  exp_complex e2;
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ(T(0,0), e2.value());
+}
+
+TEST(Expected, testCopyConstructible) {
+  exp_int e;
+  exp_int e2 = e;
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ(0, e.value());
+  EXPECT_EQ(0, e2.value());
+}
+
+TEST(Expected, testMoveConstructible) {
+  exp_int e;
+  exp_int e2 = std::move(e);
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ(0, e.value());
+  EXPECT_EQ(0, e2.value());
+
+  exp_string e3(std::string("hello"));
+  exp_string e4 = std::move(e3);
+
+  EXPECT_TRUE(e3.has_value());
+  EXPECT_TRUE(e4.has_value());
+  EXPECT_EQ("", e3.value()); // e3 is moved
+  EXPECT_EQ("hello", e4.value());
+}
+
+TEST(Expected, testCopyConstructibleFromConvertibleType) {
+  exp_double e = 3.3f;
+  exp_int e2 = e;
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ(3.3f, e.value());
+  EXPECT_EQ(3, e2.value());
+}
+
+TEST(Expected, testMoveConstructibleFromConvertibleType) {
+  exp_double e = 3.3f;
+  exp_int e2 = std::move(e);
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ(3.3f, e.value());
+  EXPECT_EQ(3, e2.value());
+}
+
+TEST(Expected, testConstructibleFromValue) {
+  exp_int e = 3;
+  exp_double e2 = 5.5f;
+  exp_string e3 = std::string("hello");
+  exp_complex e4 = T(10, 20);
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_TRUE(e3.has_value());
+  EXPECT_TRUE(e4.has_value());
+  EXPECT_EQ(3, e.value());
+  EXPECT_EQ(5.5f, e2.value());
+  EXPECT_EQ("hello", e3.value());
+  EXPECT_EQ(T(10,20), e4.value());
+}
+
+TEST(Expected, testConstructibleFromMovedValue) {
+  std::string hello = "hello";
+  exp_string e = std::move(hello);
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_EQ("hello", e.value());
+  EXPECT_EQ("", hello);
+}
+
+TEST(Expected, testConstructibleFromConvertibleValue) {
+  exp_int e = 3.3f; // double to int
+  exp_string e2 = "hello"; // char* to std::string
+  EXPECT_TRUE(e.has_value());
+  EXPECT_EQ(3, e.value());
+
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ("hello", e2.value());
+}
+
+TEST(Expected, testConstructibleFromUnexpected) {
+  exp_int::unexpected_type unexp = unexpected(10);
+  exp_int e = unexp;
+
+  exp_double::unexpected_type unexp2 = unexpected(10.5f);
+  exp_double e2 = unexp2;
+
+  exp_string::unexpected_type unexp3 = unexpected(std::string("error"));
+  exp_string e3 = unexp3;
+
+  EXPECT_FALSE(e.has_value());
+  EXPECT_FALSE(e2.has_value());
+  EXPECT_FALSE(e3.has_value());
+  EXPECT_EQ(10, e.error());
+  EXPECT_EQ(10.5f, e2.error());
+  EXPECT_EQ("error", e3.error());
+}
+
+TEST(Expected, testMoveConstructibleFromUnexpected) {
+  exp_int e = unexpected(10);
+  exp_double e2 = unexpected(10.5f);
+  exp_string e3 = unexpected(std::string("error"));
+
+  EXPECT_FALSE(e.has_value());
+  EXPECT_FALSE(e2.has_value());
+  EXPECT_FALSE(e3.has_value());
+  EXPECT_EQ(10, e.error());
+  EXPECT_EQ(10.5f, e2.error());
+  EXPECT_EQ("error", e3.error());
+}
+
+TEST(Expected, testConstructibleByForwarding) {
+  exp_string e(std::in_place, 5, 'a');
+  EXPECT_TRUE(e.has_value());
+  EXPECT_EQ("aaaaa", e.value());
+
+  exp_string e2({'a', 'b', 'c'});
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ("abc", e2.value());
+
+  exp_pair e3({"hello", 30});
+  EXPECT_TRUE(e3.has_value());
+  EXPECT_EQ("hello",e3->first);
+  EXPECT_EQ(30,e3->second);
+}
+
+TEST(Expected, testDestructible) {
+  bool destroyed = false;
+  struct T {
+    bool* flag_;
+    T(bool* flag) : flag_(flag) {}
+    ~T() { *flag_ = true; }
+  };
+  {
+    expected<T, int> exp = T(&destroyed);
+  }
+  EXPECT_TRUE(destroyed);
+}
+
+TEST(Expected, testAssignable) {
+  exp_int e = 10;
+  exp_int e2 = 20;
+  e = e2;
+
+  EXPECT_EQ(20, e.value());
+  EXPECT_EQ(20, e2.value());
+
+  exp_int e3 = 10;
+  exp_int e4 = 20;
+  e3 = std::move(e4);
+
+  EXPECT_EQ(20, e3.value());
+  EXPECT_EQ(20, e4.value());
+}
+
+TEST(Expected, testAssignableFromValue) {
+  exp_int e = 10;
+  e = 20;
+  EXPECT_EQ(20, e.value());
+
+  exp_double e2 = 3.5f;
+  e2 = 10.5f;
+  EXPECT_EQ(10.5f, e2.value());
+
+  exp_string e3 = "hello";
+  e3 = "world";
+  EXPECT_EQ("world", e3.value());
+}
+
+TEST(Expected, testAssignableFromUnexpected) {
+  exp_int e = 10;
+  e = unexpected(30);
+  EXPECT_FALSE(e.has_value());
+  EXPECT_EQ(30, e.error());
+
+  exp_double e2 = 3.5f;
+  e2 = unexpected(10.5f);
+  EXPECT_FALSE(e2.has_value());
+  EXPECT_EQ(10.5f, e2.error());
+
+  exp_string e3 = "hello";
+  e3 = unexpected("world");
+  EXPECT_FALSE(e3.has_value());
+  EXPECT_EQ("world", e3.error());
+}
+
+TEST(Expected, testAssignableFromMovedValue) {
+  std::string world = "world";
+  exp_string e = "hello";
+  e = std::move(world);
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_EQ("world", e.value());
+  EXPECT_EQ("", world);
+}
+
+TEST(Expected, testAssignableFromMovedUnexpected) {
+  std::string world = "world";
+  exp_string e = "hello";
+  e = unexpected(std::move(world));
+
+  EXPECT_FALSE(e.has_value());
+  EXPECT_EQ("world", e.error());
+  EXPECT_EQ("", world);
+}
+
+TEST(Expected, testEmplace) {
+  struct T {
+    int a;
+    double b;
+    T() {}
+    T(int a, double b) noexcept : a(a), b(b) {}
+  };
+  expected<T, int> exp;
+  T& t = exp.emplace(3, 10.5f);
+
+  EXPECT_TRUE(exp.has_value());
+  EXPECT_EQ(3, t.a);
+  EXPECT_EQ(10.5f, t.b);
+  EXPECT_EQ(3, exp.value().a);
+  EXPECT_EQ(10.5, exp.value().b);
+}
+
+TEST(Expected, testSwapExpectedExpected) {
+  exp_int e = 10;
+  exp_int e2 = 20;
+  e.swap(e2);
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ(20, e.value());
+  EXPECT_EQ(10, e2.value());
+}
+
+TEST(Expected, testSwapUnexpectedUnexpected) {
+  exp_int e = unexpected(10);
+  exp_int e2 = unexpected(20);
+  e.swap(e2);
+  EXPECT_FALSE(e.has_value());
+  EXPECT_FALSE(e2.has_value());
+  EXPECT_EQ(20, e.error());
+  EXPECT_EQ(10, e2.error());
+}
+
+TEST(Expected, testSwapExpectedUnepected) {
+  exp_int e = 10;
+  exp_int e2 = unexpected(30);
+  e.swap(e2);
+  EXPECT_FALSE(e.has_value());
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ(30, e.error());
+  EXPECT_EQ(10, e2.value());
+}
+
+TEST(Expected, testDereference) {
+  struct T {
+    int a;
+    double b;
+    T() {}
+    T(int a, double b) : a(a), b(b) {}
+  };
+  expected<T, int> exp = T(3, 10.5f);
+
+  EXPECT_EQ(3, exp->a);
+  EXPECT_EQ(10.5f, exp->b);
+
+  EXPECT_EQ(3, (*exp).a);
+  EXPECT_EQ(10.5f, (*exp).b);
+}
+
+TEST(Expected, testTest) {
+  exp_int e = 10;
+  EXPECT_TRUE(e);
+  EXPECT_TRUE(e.has_value());
+
+  exp_int e2 = unexpected(10);
+  EXPECT_FALSE(e2);
+  EXPECT_FALSE(e2.has_value());
+}
+
+TEST(Expected, testGetValue) {
+  exp_int e = 10;
+  EXPECT_EQ(10, e.value());
+  EXPECT_EQ(10, e.value_or(20));
+
+  exp_int e2 = unexpected(10);
+  EXPECT_EQ(10, e2.error());
+  EXPECT_EQ(20, e2.value_or(20));
+}
+
+TEST(Expected, testSameValues) {
+  exp_int e = 10;
+  exp_int e2 = 10;
+  EXPECT_TRUE(e == e2);
+  EXPECT_TRUE(e2 == e);
+  EXPECT_FALSE(e != e2);
+  EXPECT_FALSE(e2 != e);
+}
+
+TEST(Expected, testDifferentValues) {
+  exp_int e = 10;
+  exp_int e2 = 20;
+  EXPECT_FALSE(e == e2);
+  EXPECT_FALSE(e2 == e);
+  EXPECT_TRUE(e != e2);
+  EXPECT_TRUE(e2 != e);
+}
+
+TEST(Expected, testValueWithError) {
+  exp_int e = 10;
+  exp_int e2 = unexpected(10);
+  EXPECT_FALSE(e == e2);
+  EXPECT_FALSE(e2 == e);
+  EXPECT_TRUE(e != e2);
+  EXPECT_TRUE(e2 != e);
+}
+
+TEST(Expected, testSameErrors) {
+  exp_int e = unexpected(10);
+  exp_int e2 = unexpected(10);
+  EXPECT_TRUE(e == e2);
+  EXPECT_TRUE(e2 == e);
+  EXPECT_FALSE(e != e2);
+  EXPECT_FALSE(e2 != e);
+}
+
+TEST(Expected, testDifferentErrors) {
+  exp_int e = unexpected(10);
+  exp_int e2 = unexpected(20);
+  EXPECT_FALSE(e == e2);
+  EXPECT_FALSE(e2 == e);
+  EXPECT_TRUE(e != e2);
+  EXPECT_TRUE(e2 != e);
+}
+
+TEST(Expected, testCompareWithSameValue) {
+  exp_int e = 10;
+  int value = 10;
+  EXPECT_TRUE(e == value);
+  EXPECT_TRUE(value == e);
+  EXPECT_FALSE(e != value);
+  EXPECT_FALSE(value != e);
+}
+
+TEST(Expected, testCompareWithDifferentValue) {
+  exp_int e = 10;
+  int value = 20;
+  EXPECT_FALSE(e == value);
+  EXPECT_FALSE(value == e);
+  EXPECT_TRUE(e != value);
+  EXPECT_TRUE(value != e);
+}
+
+TEST(Expected, testCompareWithSameError) {
+  exp_int e = unexpected(10);
+  exp_int::unexpected_type error = 10;
+  EXPECT_TRUE(e == error);
+  EXPECT_TRUE(error == e);
+  EXPECT_FALSE(e != error);
+  EXPECT_FALSE(error != e);
+}
+
+TEST(Expected, testCompareWithDifferentError) {
+  exp_int e = unexpected(10);
+  exp_int::unexpected_type error = 20;
+  EXPECT_FALSE(e == error);
+  EXPECT_FALSE(error == e);
+  EXPECT_TRUE(e != error);
+  EXPECT_TRUE(error != e);
+}
+
+TEST(Expected, testDivideExample) {
+  struct QR {
+    int quotient;
+    int remainder;
+    QR(int q, int r) noexcept : quotient(q), remainder(r) {}
+    bool operator==(const QR& rhs) const {
+      return quotient == rhs.quotient && remainder == rhs.remainder;
+    }
+    bool operator!=(const QR& rhs) const {
+      return quotient != rhs.quotient || remainder == rhs.remainder;
+    }
+  };
+
+  auto divide = [](int x, int y) -> expected<QR,E> {
+    if (y == 0) {
+      return unexpected(E("divide by zero", -1));
+    } else {
+      return QR(x / y, x % y);
+    }
+  };
+
+  EXPECT_FALSE(divide(10, 0));
+  EXPECT_EQ("divide by zero", divide(10, 0).error().message);
+  EXPECT_EQ(-1, divide(10, 0).error().cause);
+
+  EXPECT_TRUE(divide(10, 3));
+  EXPECT_EQ(QR(3, 1), divide(10, 3));
+}
+
+TEST(Expected, testPair) {
+  auto test = [](bool yes) -> exp_pair {
+    if (yes) {
+      return exp_pair({"yes", 42});
+    } else {
+      return unexpected(42);
+    }
+  };
+
+  auto r = test(true);
+  EXPECT_TRUE(r);
+  EXPECT_EQ("yes", r->first);
+}
+
+// copied from result_test.cpp
+struct ConstructorTracker {
+  static size_t constructor_called;
+  static size_t copy_constructor_called;
+  static size_t move_constructor_called;
+  static size_t copy_assignment_called;
+  static size_t move_assignment_called;
+
+  template <typename T,
+    typename std::enable_if_t<std::is_convertible_v<T, std::string>>* = nullptr>
+  ConstructorTracker(T&& string) : string(string) {
+    ++constructor_called;
+  }
+  ConstructorTracker(const ConstructorTracker& ct) {
+    ++copy_constructor_called;
+    string = ct.string;
+  }
+  ConstructorTracker(ConstructorTracker&& ct) noexcept {
+    ++move_constructor_called;
+    string = std::move(ct.string);
+  }
+  ConstructorTracker& operator=(const ConstructorTracker& ct) {
+    ++copy_assignment_called;
+    string = ct.string;
+    return *this;
+  }
+  ConstructorTracker& operator=(ConstructorTracker&& ct) noexcept {
+    ++move_assignment_called;
+    string = std::move(ct.string);
+    return *this;
+  }
+  static void Reset() {
+    constructor_called = 0;
+    copy_constructor_called = 0;
+    move_constructor_called = 0;
+    copy_assignment_called = 0;
+    move_assignment_called = 0;
+  }
+  std::string string;
+};
+
+size_t ConstructorTracker::constructor_called = 0;
+size_t ConstructorTracker::copy_constructor_called = 0;
+size_t ConstructorTracker::move_constructor_called = 0;
+size_t ConstructorTracker::copy_assignment_called = 0;
+size_t ConstructorTracker::move_assignment_called = 0;
+
+typedef expected<ConstructorTracker, int> exp_track;
+
+TEST(Expected, testNumberOfCopies) {
+  // default constructor
+  ConstructorTracker::Reset();
+  exp_track e("hello");
+  EXPECT_EQ(1U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+
+  // copy constructor
+  ConstructorTracker::Reset();
+  exp_track e2 = e;
+  EXPECT_EQ(0U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(1U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+
+  // move constructor
+  ConstructorTracker::Reset();
+  exp_track e3 = std::move(e);
+  EXPECT_EQ(0U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(1U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+
+  // construct from lvalue
+  ConstructorTracker::Reset();
+  ConstructorTracker ct = "hello";
+  exp_track e4(ct);
+  EXPECT_EQ(1U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(1U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+
+  // construct from rvalue
+  ConstructorTracker::Reset();
+  ConstructorTracker ct2 = "hello";
+  exp_track e5(std::move(ct2));
+  EXPECT_EQ(1U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(1U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+
+  // copy assignment
+  ConstructorTracker::Reset();
+  exp_track e6 = "hello";
+  exp_track e7 = "world";
+  e7 = e6;
+  EXPECT_EQ(2U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(1U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+
+  // move assignment
+  ConstructorTracker::Reset();
+  exp_track e8 = "hello";
+  exp_track e9 = "world";
+  e9 = std::move(e8);
+  EXPECT_EQ(2U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(1U, ConstructorTracker::move_assignment_called);
+
+  // swap
+  ConstructorTracker::Reset();
+  exp_track e10 = "hello";
+  exp_track e11 = "world";
+  std::swap(e10, e11);
+  EXPECT_EQ(2U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(1U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(2U, ConstructorTracker::move_assignment_called);
+}
+
+TEST(Expected, testNoCopyOnReturn) {
+  auto test = [](const std::string& in) -> exp_track {
+    if (in.empty()) {
+      return "literal string";
+    }
+    if (in == "test2") {
+      return ConstructorTracker(in + in + "2");
+    }
+    ConstructorTracker result(in + " " + in);
+    return result;
+  };
+
+  ConstructorTracker::Reset();
+  auto result1 = test("");
+  ASSERT_TRUE(result1);
+  EXPECT_EQ("literal string", result1->string);
+  EXPECT_EQ(1U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+
+  ConstructorTracker::Reset();
+  auto result2 = test("test2");
+  ASSERT_TRUE(result2);
+  EXPECT_EQ("test2test22", result2->string);
+  EXPECT_EQ(1U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(1U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+
+  ConstructorTracker::Reset();
+  auto result3 = test("test3");
+  ASSERT_TRUE(result3);
+  EXPECT_EQ("test3 test3", result3->string);
+  EXPECT_EQ(1U, ConstructorTracker::constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_constructor_called);
+  EXPECT_EQ(1U, ConstructorTracker::move_constructor_called);
+  EXPECT_EQ(0U, ConstructorTracker::copy_assignment_called);
+  EXPECT_EQ(0U, ConstructorTracker::move_assignment_called);
+}
+
+TEST(Expected, testNested) {
+  expected<exp_string, std::string> e = "hello";
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_TRUE(e.value().has_value());
+  EXPECT_TRUE(e);
+  EXPECT_TRUE(*e);
+  EXPECT_EQ("hello", e.value().value());
+
+  expected<exp_string, std::string> e2 = unexpected("world");
+  EXPECT_FALSE(e2.has_value());
+  EXPECT_FALSE(e2);
+  EXPECT_EQ("world", e2.error());
+
+  expected<exp_string, std::string> e3 = exp_string(unexpected("world"));
+  EXPECT_TRUE(e3.has_value());
+  EXPECT_FALSE(e3.value().has_value());
+  EXPECT_TRUE(e3);
+  EXPECT_FALSE(*e3);
+  EXPECT_EQ("world", e3.value().error());
+}
+
+constexpr bool equals(const char* a, const char* b) {
+  return (a == nullptr && b == nullptr) ||
+      (a != nullptr && b != nullptr && *a == *b &&
+       (*a == '\0' || equals(a + 1, b + 1)));
+}
+
+TEST(Expected, testConstexpr) {
+  // Compliation error will occur if these expressions can't be
+  // evaluated at compile time
+  constexpr exp_int e(3);
+  constexpr exp_int::unexpected_type err(3);
+  constexpr int i = 4;
+
+  // default constructor
+  static_assert(exp_int().value() == 0);
+  // copy constructor
+  static_assert(exp_int(e).value() == 3);
+  // move constructor
+  static_assert(exp_int(exp_int(4)).value() == 4);
+  // copy construct from value
+  static_assert(exp_int(i).value() == 4);
+  // copy construct from unexpected
+  static_assert(exp_int(err).error() == 3);
+  // move costruct from unexpected
+  static_assert(exp_int(unexpected(3)).error() == 3);
+  // observers
+  static_assert(*exp_int(3) == 3);
+  static_assert(exp_int(3).has_value() == true);
+  static_assert(exp_int(3).value_or(4) == 3);
+
+  typedef expected<const char*, int> exp_s;
+  constexpr exp_s s("hello");
+  constexpr const char* c = "hello";
+  static_assert(equals(exp_s().value(), nullptr));
+  static_assert(equals(exp_s(s).value(), "hello"));
+  static_assert(equals(exp_s(exp_s("hello")).value(), "hello"));
+  static_assert(equals(exp_s("hello").value(), "hello"));
+  static_assert(equals(exp_s(c).value(), "hello"));
+}
+
+TEST(Expected, testWithNonConstructible) {
+   struct AssertNotConstructed {
+     AssertNotConstructed() = delete;
+   };
+
+   expected<int, AssertNotConstructed> v(42);
+   EXPECT_TRUE(v.has_value());
+   EXPECT_EQ(42, v.value());
+
+   expected<AssertNotConstructed, int> e(unexpected(42));
+   EXPECT_FALSE(e.has_value());
+   EXPECT_EQ(42, e.error());
+}
+
+TEST(Expected, testWithMoveOnlyType) {
+  typedef expected<std::unique_ptr<int>,std::unique_ptr<int>> exp_ptr;
+  exp_ptr e(std::make_unique<int>(3));
+  exp_ptr e2(unexpected(std::make_unique<int>(4)));
+
+  EXPECT_TRUE(e.has_value());
+  EXPECT_FALSE(e2.has_value());
+  EXPECT_EQ(3, *(e.value()));
+  EXPECT_EQ(4, *(e2.error()));
+
+  e2 = std::move(e);
+  EXPECT_TRUE(e.has_value());
+  EXPECT_TRUE(e2.has_value());
+  EXPECT_EQ(3, *(e2.value()));
+}
diff --git a/base/include/android-base/expected.h b/base/include/android-base/expected.h
new file mode 100644
index 0000000..d70e50a
--- /dev/null
+++ b/base/include/android-base/expected.h
@@ -0,0 +1,600 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <algorithm>
+#include <initializer_list>
+#include <type_traits>
+#include <utility>
+#include <variant>
+
+// android::base::expected is an Android implementation of the std::expected
+// proposal.
+// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0323r7.html
+//
+// Usage:
+// using android::base::expected;
+// using android::base::unexpected;
+//
+// expected<double,std::string> safe_divide(double i, double j) {
+//   if (j == 0) return unexpected("divide by zero");
+//   else return i / j;
+// }
+//
+// void test() {
+//   auto q = safe_divide(10, 0);
+//   if (q) { printf("%f\n", q.value()); }
+//   else { printf("%s\n", q.error().c_str()); }
+// }
+//
+// When the proposal becomes part of the standard and is implemented by
+// libcxx, this will be removed and android::base::expected will be
+// type alias to std::expected.
+//
+
+namespace android {
+namespace base {
+
+// Synopsis
+template<class T, class E>
+    class expected;
+
+template<class E>
+    class unexpected;
+template<class E>
+  unexpected(E) -> unexpected<E>;
+
+template<class E>
+   class bad_expected_access;
+
+template<>
+   class bad_expected_access<void>;
+
+struct unexpect_t {
+   explicit unexpect_t() = default;
+};
+inline constexpr unexpect_t unexpect{};
+
+// macros for SFINAE
+#define _ENABLE_IF(...) \
+  , std::enable_if_t<(__VA_ARGS__)>* = nullptr
+
+// Define NODISCARD_EXPECTED to prevent expected<T,E> from being
+// ignored when used as a return value. This is off by default.
+#ifdef NODISCARD_EXPECTED
+#define _NODISCARD_ [[nodiscard]]
+#else
+#define _NODISCARD_
+#endif
+
+// Class expected
+template<class T, class E>
+class _NODISCARD_ expected {
+ public:
+  using value_type = T;
+  using error_type = E;
+  using unexpected_type = unexpected<E>;
+
+  template<class U>
+  using rebind = expected<U, error_type>;
+
+  // constructors
+  constexpr expected() = default;
+  constexpr expected(const expected& rhs) = default;
+  constexpr expected(expected&& rhs) noexcept  = default;
+
+  template<class U, class G _ENABLE_IF(
+    std::is_constructible_v<T, const U&> &&
+    std::is_constructible_v<E, const G&> &&
+    !std::is_constructible_v<T, expected<U, G>&> &&
+    !std::is_constructible_v<T, expected<U, G>&&> &&
+    !std::is_constructible_v<T, const expected<U, G>&> &&
+    !std::is_constructible_v<T, const expected<U, G>&&> &&
+    !std::is_convertible_v<expected<U, G>&, T> &&
+    !std::is_convertible_v<expected<U, G>&&, T> &&
+    !std::is_convertible_v<const expected<U, G>&, T> &&
+    !std::is_convertible_v<const expected<U, G>&&, T> &&
+    !(!std::is_convertible_v<const U&, T> ||
+     !std::is_convertible_v<const G&, E>) /* non-explicit */
+  )>
+  constexpr expected(const expected<U, G>& rhs) {
+    if (rhs.has_value()) var_ = rhs.value();
+    else var_ = unexpected(rhs.error());
+  }
+
+  template<class U, class G _ENABLE_IF(
+    std::is_constructible_v<T, const U&> &&
+    std::is_constructible_v<E, const G&> &&
+    !std::is_constructible_v<T, expected<U, G>&> &&
+    !std::is_constructible_v<T, expected<U, G>&&> &&
+    !std::is_constructible_v<T, const expected<U, G>&> &&
+    !std::is_constructible_v<T, const expected<U, G>&&> &&
+    !std::is_convertible_v<expected<U, G>&, T> &&
+    !std::is_convertible_v<expected<U, G>&&, T> &&
+    !std::is_convertible_v<const expected<U, G>&, T> &&
+    !std::is_convertible_v<const expected<U, G>&&, T> &&
+    (!std::is_convertible_v<const U&, T> ||
+     !std::is_convertible_v<const G&, E>) /* explicit */
+  )>
+  constexpr explicit expected(const expected<U, G>& rhs) {
+    if (rhs.has_value()) var_ = rhs.value();
+    else var_ = unexpected(rhs.error());
+  }
+
+  template<class U, class G _ENABLE_IF(
+    std::is_constructible_v<T, const U&> &&
+    std::is_constructible_v<E, const G&> &&
+    !std::is_constructible_v<T, expected<U, G>&> &&
+    !std::is_constructible_v<T, expected<U, G>&&> &&
+    !std::is_constructible_v<T, const expected<U, G>&> &&
+    !std::is_constructible_v<T, const expected<U, G>&&> &&
+    !std::is_convertible_v<expected<U, G>&, T> &&
+    !std::is_convertible_v<expected<U, G>&&, T> &&
+    !std::is_convertible_v<const expected<U, G>&, T> &&
+    !std::is_convertible_v<const expected<U, G>&&, T> &&
+    !(!std::is_convertible_v<const U&, T> ||
+     !std::is_convertible_v<const G&, E>) /* non-explicit */
+  )>
+  constexpr expected(expected<U, G>&& rhs) {
+    if (rhs.has_value()) var_ = std::move(rhs.value());
+    else var_ = unexpected(std::move(rhs.error()));
+  }
+
+  template<class U, class G _ENABLE_IF(
+    std::is_constructible_v<T, const U&> &&
+    std::is_constructible_v<E, const G&> &&
+    !std::is_constructible_v<T, expected<U, G>&> &&
+    !std::is_constructible_v<T, expected<U, G>&&> &&
+    !std::is_constructible_v<T, const expected<U, G>&> &&
+    !std::is_constructible_v<T, const expected<U, G>&&> &&
+    !std::is_convertible_v<expected<U, G>&, T> &&
+    !std::is_convertible_v<expected<U, G>&&, T> &&
+    !std::is_convertible_v<const expected<U, G>&, T> &&
+    !std::is_convertible_v<const expected<U, G>&&, T> &&
+    (!std::is_convertible_v<const U&, T> ||
+     !std::is_convertible_v<const G&, E>) /* explicit */
+  )>
+  constexpr explicit expected(expected<U, G>&& rhs) {
+    if (rhs.has_value()) var_ = std::move(rhs.value());
+    else var_ = unexpected(std::move(rhs.error()));
+  }
+
+  template<class U = T _ENABLE_IF(
+    std::is_constructible_v<T, U&&> &&
+    std::is_convertible_v<U&&,T> /* non-explicit */
+  )>
+  constexpr expected(U&& v)
+  : var_(std::in_place_index<0>, std::forward<U>(v)) {}
+
+  template<class U = T _ENABLE_IF(
+    std::is_constructible_v<T, U&&> &&
+    !std::is_convertible_v<U&&,T> /* explicit */
+  )>
+  constexpr explicit expected(U&& v)
+  : var_(std::in_place_index<0>, T(std::forward<U>(v))) {}
+
+  template<class G = E _ENABLE_IF(
+    std::is_constructible_v<E, const G&> &&
+    std::is_convertible_v<const G&, E> /* non-explicit */
+  )>
+  constexpr expected(const unexpected<G>& e)
+  : var_(std::in_place_index<1>, e.value()) {}
+
+  template<class G = E _ENABLE_IF(
+    std::is_constructible_v<E, const G&> &&
+    !std::is_convertible_v<const G&, E> /* explicit */
+  )>
+  constexpr explicit expected(const unexpected<G>& e)
+  : var_(std::in_place_index<1>, E(e.value())) {}
+
+  template<class G = E _ENABLE_IF(
+    std::is_constructible_v<E, G&&> &&
+    std::is_convertible_v<G&&, E> /* non-explicit */
+  )>
+  constexpr expected(unexpected<G>&& e)
+  : var_(std::in_place_index<1>, std::move(e.value())) {}
+
+  template<class G = E _ENABLE_IF(
+    std::is_constructible_v<E, G&&> &&
+    !std::is_convertible_v<G&&, E> /* explicit */
+  )>
+  constexpr explicit expected(unexpected<G>&& e)
+  : var_(std::in_place_index<1>, E(std::move(e.value()))) {}
+
+  template<class... Args _ENABLE_IF(
+    std::is_constructible_v<T, Args&&...>
+  )>
+  constexpr explicit expected(std::in_place_t, Args&&... args)
+  : var_(std::in_place_index<0>, std::forward<Args>(args)...) {}
+
+  template<class U, class... Args _ENABLE_IF(
+    std::is_constructible_v<T, std::initializer_list<U>&, Args...>
+  )>
+  constexpr explicit expected(std::in_place_t, std::initializer_list<U> il, Args&&... args)
+  : var_(std::in_place_index<0>, il, std::forward<Args>(args)...) {}
+
+  template<class... Args _ENABLE_IF(
+    std::is_constructible_v<E, Args...>
+  )>
+  constexpr explicit expected(unexpect_t, Args&&... args)
+  : var_(unexpected_type(std::forward<Args>(args)...)) {}
+
+  template<class U, class... Args _ENABLE_IF(
+    std::is_constructible_v<E, std::initializer_list<U>&, Args...>
+  )>
+  constexpr explicit expected(unexpect_t, std::initializer_list<U> il, Args&&... args)
+  : var_(unexpected_type(il, std::forward<Args>(args)...)) {}
+
+  // destructor
+  ~expected() = default;
+
+  // assignment
+// TODO(b/132145659) enable assignment operator only when the condition
+// satisfies. SFNAIE doesn't work here because assignment operator should be
+// non-template. We could workaround this by defining a templated parent class
+// having the assignment operator. This incomplete implementation however
+// doesn't allow us to copy assign expected<T,E> even when T is non-copy
+// assignable. The copy assignment will fail by the underlying std::variant
+// anyway though the error message won't be clear.
+//  std::enable_if_t<(
+//    std::is_copy_assignable_v<T> &&
+//    std::is_copy_constructible_v<T> &&
+//    std::is_copy_assignable_v<E> &&
+//    std::is_copy_constructible_v<E> &&
+//    (std::is_nothrow_move_constructible_v<E> ||
+//     std::is_nothrow_move_constructible_v<T>)
+//  ), expected&>
+  expected& operator=(const expected& rhs) {
+    var_ = rhs.var_;
+    return *this;
+  }
+//  std::enable_if_t<(
+//    std::is_move_constructible_v<T> &&
+//    std::is_move_assignable_v<T> &&
+//    std::is_nothrow_move_constructible_v<E> &&
+//    std::is_nothrow_move_assignable_v<E>
+//  ), expected&>
+  expected& operator=(expected&& rhs) noexcept {
+    var_ = std::move(rhs.var_);
+    return *this;
+  }
+
+  template<class U = T _ENABLE_IF(
+    !std::is_void_v<T> &&
+    std::is_constructible_v<T,U> &&
+    std::is_assignable_v<T&,U> &&
+    std::is_nothrow_move_constructible_v<E>
+  )>
+  expected& operator=(U&& rhs) {
+    var_ = T(std::forward<U>(rhs));
+    return *this;
+  }
+
+  template<class G = E>
+  // TODO: std::is_nothrow_copy_constructible_v<E> && std::is_copy_assignable_v<E>
+  expected& operator=(const unexpected<G>& rhs) {
+    var_ = rhs;
+    return *this;
+  }
+
+  template<class G = E _ENABLE_IF(
+    std::is_nothrow_move_constructible_v<G> &&
+    std::is_move_assignable_v<G>
+  )>
+  expected& operator=(unexpected<G>&& rhs) {
+    var_ = std::move(rhs);
+    return *this;
+  }
+
+  // modifiers
+  template<class... Args _ENABLE_IF(
+    std::is_nothrow_constructible_v<T, Args...>
+  )>
+  T& emplace(Args&&... args) {
+    expected(std::in_place, std::forward<Args>(args)...).swap(*this);
+    return value();
+  }
+
+  template<class U, class... Args _ENABLE_IF(
+    std::is_nothrow_constructible_v<T, std::initializer_list<U>&, Args...>
+  )>
+  T& emplace(std::initializer_list<U> il, Args&&... args) {
+    expected(std::in_place, il, std::forward<Args>(args)...).swap(*this);
+    return value();
+  }
+
+  // swap
+  template<typename U = T, typename = std::enable_if_t<(
+    std::is_swappable_v<U> &&
+    std::is_swappable_v<E> &&
+    (std::is_move_constructible_v<U> ||
+     std::is_move_constructible_v<E>))>>
+  void swap(expected& rhs) noexcept(
+    std::is_nothrow_move_constructible_v<T> &&
+    std::is_nothrow_swappable_v<T> &&
+    std::is_nothrow_move_constructible_v<E> &&
+    std::is_nothrow_swappable_v<E>) {
+    var_.swap(rhs.var_);
+  }
+
+  // observers
+  constexpr const T* operator->() const { return std::addressof(value()); }
+  constexpr T* operator->() { return std::addressof(value()); }
+  constexpr const T& operator*() const& { return value(); }
+  constexpr T& operator*() & { return value(); }
+  constexpr const T&& operator*() const&& { return std::move(std::get<T>(var_)); }
+  constexpr T&& operator*() && { return std::move(std::get<T>(var_)); }
+
+  constexpr explicit operator bool() const noexcept { return has_value(); }
+  constexpr bool has_value() const noexcept { return var_.index() == 0; }
+
+  constexpr const T& value() const& { return std::get<T>(var_); }
+  constexpr T& value() & { return std::get<T>(var_); }
+  constexpr const T&& value() const&& { return std::move(std::get<T>(var_)); }
+  constexpr T&& value() && { return std::move(std::get<T>(var_)); }
+
+  constexpr const E& error() const& { return std::get<unexpected_type>(var_).value(); }
+  constexpr E& error() & { return std::get<unexpected_type>(var_).value(); }
+  constexpr const E&& error() const&& { return std::move(std::get<unexpected_type>(var_)).value(); }
+  constexpr E&& error() && { return std::move(std::get<unexpected_type>(var_)).value(); }
+
+  template<class U _ENABLE_IF(
+    std::is_copy_constructible_v<T> &&
+    std::is_convertible_v<U, T>
+  )>
+  constexpr T value_or(U&& v) const& {
+    if (has_value()) return value();
+    else return static_cast<T>(std::forward<U>(v));
+  }
+
+  template<class U _ENABLE_IF(
+    std::is_move_constructible_v<T> &&
+    std::is_convertible_v<U, T>
+  )>
+  constexpr T value_or(U&& v) && {
+    if (has_value()) return std::move(value());
+    else return static_cast<T>(std::forward<U>(v));
+  }
+
+  // expected equality operators
+  template<class T1, class E1, class T2, class E2>
+  friend constexpr bool operator==(const expected<T1, E1>& x, const expected<T2, E2>& y);
+  template<class T1, class E1, class T2, class E2>
+  friend constexpr bool operator!=(const expected<T1, E1>& x, const expected<T2, E2>& y);
+
+  // comparison with T
+  template<class T1, class E1, class T2>
+  friend constexpr bool operator==(const expected<T1, E1>&, const T2&);
+  template<class T1, class E1, class T2>
+  friend constexpr bool operator==(const T2&, const expected<T1, E1>&);
+  template<class T1, class E1, class T2>
+  friend constexpr bool operator!=(const expected<T1, E1>&, const T2&);
+  template<class T1, class E1, class T2>
+  friend constexpr bool operator!=(const T2&, const expected<T1, E1>&);
+
+  // Comparison with unexpected<E>
+  template<class T1, class E1, class E2>
+  friend constexpr bool operator==(const expected<T1, E1>&, const unexpected<E2>&);
+  template<class T1, class E1, class E2>
+  friend constexpr bool operator==(const unexpected<E2>&, const expected<T1, E1>&);
+  template<class T1, class E1, class E2>
+  friend constexpr bool operator!=(const expected<T1, E1>&, const unexpected<E2>&);
+  template<class T1, class E1, class E2>
+  friend constexpr bool operator!=(const unexpected<E2>&, const expected<T1, E1>&);
+
+  // Specialized algorithms
+  template<class T1, class E1>
+  friend void swap(expected<T1, E1>&, expected<T1, E1>&) noexcept;
+
+ private:
+    std::variant<value_type, unexpected_type> var_;
+};
+
+template<class T1, class E1, class T2, class E2>
+constexpr bool operator==(const expected<T1, E1>& x, const expected<T2, E2>& y) {
+  if (x.has_value() != y.has_value()) {
+    return false;
+  } else if (!x.has_value()) {
+    return x.error() == y.error();
+  } else {
+    return *x == *y;
+  }
+}
+
+template<class T1, class E1, class T2, class E2>
+constexpr bool operator!=(const expected<T1, E1>& x, const expected<T2, E2>& y) {
+  if (x.has_value() != y.has_value()) {
+    return true;
+  } else if (!x.has_value()) {
+    return x.error() != y.error();
+  } else {
+    return *x != *y;
+  }
+}
+
+// comparison with T
+template<class T1, class E1, class T2>
+constexpr bool operator==(const expected<T1, E1>& x, const T2& y) {
+  return x.has_value() && (*x == y);
+}
+template<class T1, class E1, class T2>
+constexpr bool operator==(const T2& x, const expected<T1, E1>& y) {
+  return y.has_value() && (x == *y);
+}
+template<class T1, class E1, class T2>
+constexpr bool operator!=(const expected<T1, E1>& x, const T2& y) {
+  return !x.has_value() || (*x != y);
+}
+template<class T1, class E1, class T2>
+constexpr bool operator!=(const T2& x, const expected<T1, E1>& y) {
+  return !y.has_value() || (x != *y);
+}
+
+// Comparison with unexpected<E>
+template<class T1, class E1, class E2>
+constexpr bool operator==(const expected<T1, E1>& x, const unexpected<E2>& y) {
+  return !x.has_value() && (x.error() == y.value());
+}
+template<class T1, class E1, class E2>
+constexpr bool operator==(const unexpected<E2>& x, const expected<T1, E1>& y) {
+  return !y.has_value() && (x.value() == y.error());
+}
+template<class T1, class E1, class E2>
+constexpr bool operator!=(const expected<T1, E1>& x, const unexpected<E2>& y) {
+  return x.has_value() || (x.error() != y.value());
+}
+template<class T1, class E1, class E2>
+constexpr bool operator!=(const unexpected<E2>& x, const expected<T1, E1>& y) {
+  return y.has_value() || (x.value() != y.error());
+}
+
+template<class E>
+class unexpected {
+ public:
+  // constructors
+  constexpr unexpected(const unexpected&) = default;
+  constexpr unexpected(unexpected&&) = default;
+
+  template<class Err = E _ENABLE_IF(
+    std::is_constructible_v<E, Err>
+  )>
+  constexpr unexpected(Err&& e)
+  : val_(std::forward<Err>(e)) {}
+
+  template<class U, class... Args _ENABLE_IF(
+    std::is_constructible_v<E, std::initializer_list<U>&, Args...>
+  )>
+  constexpr explicit unexpected(std::in_place_t, std::initializer_list<U> il, Args&&... args)
+  : val_(il, std::forward<Args>(args)...) {}
+
+  template<class Err _ENABLE_IF(
+    std::is_constructible_v<E, Err> &&
+    !std::is_constructible_v<E, unexpected<Err>&> &&
+    !std::is_constructible_v<E, unexpected<Err>> &&
+    !std::is_constructible_v<E, const unexpected<Err>&> &&
+    !std::is_constructible_v<E, const unexpected<Err>> &&
+    !std::is_convertible_v<unexpected<Err>&, E> &&
+    !std::is_convertible_v<unexpected<Err>, E> &&
+    !std::is_convertible_v<const unexpected<Err>&, E> &&
+    !std::is_convertible_v<const unexpected<Err>, E> &&
+    std::is_convertible_v<Err, E> /* non-explicit */
+  )>
+  constexpr unexpected(const unexpected<Err>& rhs)
+  : val_(rhs.value()) {}
+
+  template<class Err _ENABLE_IF(
+    std::is_constructible_v<E, Err> &&
+    !std::is_constructible_v<E, unexpected<Err>&> &&
+    !std::is_constructible_v<E, unexpected<Err>> &&
+    !std::is_constructible_v<E, const unexpected<Err>&> &&
+    !std::is_constructible_v<E, const unexpected<Err>> &&
+    !std::is_convertible_v<unexpected<Err>&, E> &&
+    !std::is_convertible_v<unexpected<Err>, E> &&
+    !std::is_convertible_v<const unexpected<Err>&, E> &&
+    !std::is_convertible_v<const unexpected<Err>, E> &&
+    !std::is_convertible_v<Err, E> /* explicit */
+  )>
+  constexpr explicit unexpected(const unexpected<Err>& rhs)
+  : val_(E(rhs.value())) {}
+
+  template<class Err _ENABLE_IF(
+    std::is_constructible_v<E, Err> &&
+    !std::is_constructible_v<E, unexpected<Err>&> &&
+    !std::is_constructible_v<E, unexpected<Err>> &&
+    !std::is_constructible_v<E, const unexpected<Err>&> &&
+    !std::is_constructible_v<E, const unexpected<Err>> &&
+    !std::is_convertible_v<unexpected<Err>&, E> &&
+    !std::is_convertible_v<unexpected<Err>, E> &&
+    !std::is_convertible_v<const unexpected<Err>&, E> &&
+    !std::is_convertible_v<const unexpected<Err>, E> &&
+    std::is_convertible_v<Err, E> /* non-explicit */
+  )>
+  constexpr unexpected(unexpected<Err>&& rhs)
+  : val_(std::move(rhs.value())) {}
+
+  template<class Err _ENABLE_IF(
+    std::is_constructible_v<E, Err> &&
+    !std::is_constructible_v<E, unexpected<Err>&> &&
+    !std::is_constructible_v<E, unexpected<Err>> &&
+    !std::is_constructible_v<E, const unexpected<Err>&> &&
+    !std::is_constructible_v<E, const unexpected<Err>> &&
+    !std::is_convertible_v<unexpected<Err>&, E> &&
+    !std::is_convertible_v<unexpected<Err>, E> &&
+    !std::is_convertible_v<const unexpected<Err>&, E> &&
+    !std::is_convertible_v<const unexpected<Err>, E> &&
+    !std::is_convertible_v<Err, E> /* explicit */
+  )>
+  constexpr explicit unexpected(unexpected<Err>&& rhs)
+  : val_(E(std::move(rhs.value()))) {}
+
+  // assignment
+  constexpr unexpected& operator=(const unexpected&) = default;
+  constexpr unexpected& operator=(unexpected&&) = default;
+  template<class Err = E>
+  constexpr unexpected& operator=(const unexpected<Err>& rhs) {
+    val_ = rhs.value();
+    return *this;
+  }
+  template<class Err = E>
+  constexpr unexpected& operator=(unexpected<Err>&& rhs) {
+    val_ = std::forward<E>(rhs.value());
+    return *this;
+  }
+
+  // observer
+  constexpr const E& value() const& noexcept { return val_; }
+  constexpr E& value() & noexcept { return val_; }
+  constexpr const E&& value() const&& noexcept { return std::move(val_); }
+  constexpr E&& value() && noexcept { return std::move(val_); }
+
+  void swap(unexpected& other) noexcept { std::swap(val_, other.val_); }
+
+  template<class E1, class E2>
+  friend constexpr bool
+  operator==(const unexpected<E1>& e1, const unexpected<E2>& e2);
+  template<class E1, class E2>
+  friend constexpr bool
+  operator!=(const unexpected<E1>& e1, const unexpected<E2>& e2);
+
+  template<class E1>
+  friend void swap(unexpected<E1>& x, unexpected<E1>& y) noexcept(noexcept(x.swap(y)));
+ private:
+    E val_;
+};
+
+template<class E1, class E2>
+constexpr bool
+operator==(const unexpected<E1>& e1, const unexpected<E2>& e2) {
+  return e1.value() == e2.value();
+}
+
+template<class E1, class E2>
+constexpr bool
+operator!=(const unexpected<E1>& e1, const unexpected<E2>& e2) {
+  return e1.value() != e2.value();
+}
+
+template<class E1>
+void swap(unexpected<E1>& x, unexpected<E1>& y) noexcept(noexcept(x.swap(y))) {
+  x.swap(y);
+}
+
+// TODO: bad_expected_access class
+
+#undef _ENABLE_IF
+#undef _NODISCARD_
+
+}  // namespace base
+}  // namespace android
diff --git a/bootstat/bootstat.cpp b/bootstat/bootstat.cpp
index c091ff7..b26f83b 100644
--- a/bootstat/bootstat.cpp
+++ b/bootstat/bootstat.cpp
@@ -140,7 +140,7 @@
     {"mba_err", 13},
     {"Watchdog", 14},
     {"Panic", 15},
-    {"power_key", 16},
+    {"power_key", 16},  // Mediatek
     {"power_on", 17},
     {"Reboot", 18},
     {"rtc", 19},
@@ -203,13 +203,13 @@
     {"shutdown,hibernate", 74},  // Suspend to DISK
     {"power_on_key", 75},
     {"reboot_by_key", 76},
-    {"wdt_by_pass_pwk", 77},
+    {"wdt_by_pass_pwk", 77},  // Mediatek
     {"reboot_longkey", 78},
     {"powerkey", 79},
-    {"usb", 80},
-    {"wdt", 81},
-    {"tool_by_pass_pwk", 82},
-    {"2sec_reboot", 83},
+    {"usb", 80},               // Mediatek
+    {"wdt", 81},               // Mediatek
+    {"tool_by_pass_pwk", 82},  // Mediatek
+    {"2sec_reboot", 83},       // Mediatek
     {"reboot,by_key", 84},
     {"reboot,longkey", 85},
     {"reboot,2sec", 86},  // Deprecate in two years, replaced with cold,rtc,2sec
@@ -276,10 +276,10 @@
     {"software_master", 147},
     {"cold,charger", 148},
     {"cold,rtc", 149},
-    {"cold,rtc,2sec", 150},
-    {"reboot,tool", 151},
-    {"reboot,wdt", 152},
-    {"reboot,unknown", 153},
+    {"cold,rtc,2sec", 150},   // Mediatek
+    {"reboot,tool", 151},     // Mediatek
+    {"reboot,wdt", 152},      // Mediatek
+    {"reboot,unknown", 153},  // Mediatek
     {"kernel_panic,audit", 154},
     {"kernel_panic,atomic", 155},
     {"kernel_panic,hung", 156},
@@ -304,6 +304,12 @@
     {"reboot,pmic_off_fault,.*", 175},
     {"reboot,pmic_off_s3rst,.*", 176},
     {"reboot,pmic_off_other,.*", 177},
+    {"reboot,fastboot_menu", 178},
+    {"reboot,recovery_menu", 179},
+    {"reboot,recovery_ui", 180},
+    {"shutdown,fastboot", 181},
+    {"shutdown,recovery", 182},
+    {"reboot,unknown[0-9]*", 183},
 };
 
 // Converts a string value representing the reason the system booted to an
@@ -1086,17 +1092,8 @@
 void LogBootInfoToStatsd(std::chrono::milliseconds end_time,
                          std::chrono::milliseconds total_duration, int32_t bootloader_duration_ms,
                          double time_since_last_boot_sec) {
-  const auto reason = android::base::GetProperty(bootloader_reboot_reason_property, "");
-
-  if (reason.empty()) {
-    android::util::stats_write(android::util::BOOT_SEQUENCE_REPORTED, "<EMPTY>", "<EMPTY>",
-                               end_time.count(), total_duration.count(),
-                               (int64_t)bootloader_duration_ms,
-                               (int64_t)time_since_last_boot_sec * 1000);
-    return;
-  }
-
-  const auto system_reason = android::base::GetProperty(system_reboot_reason_property, "");
+  const auto reason = android::base::GetProperty(bootloader_reboot_reason_property, "<EMPTY>");
+  const auto system_reason = android::base::GetProperty(system_reboot_reason_property, "<EMPTY>");
   android::util::stats_write(android::util::BOOT_SEQUENCE_REPORTED, reason.c_str(),
                              system_reason.c_str(), end_time.count(), total_duration.count(),
                              (int64_t)bootloader_duration_ms,
diff --git a/fastboot/device/usb_client.cpp b/fastboot/device/usb_client.cpp
index 511bd5c..2f0cca7 100644
--- a/fastboot/device/usb_client.cpp
+++ b/fastboot/device/usb_client.cpp
@@ -33,7 +33,7 @@
 constexpr int kMaxPacketsizeSs = 1024;
 
 constexpr size_t kFbFfsNumBufs = 16;
-constexpr size_t kFbFfsBufSize = 32768;
+constexpr size_t kFbFfsBufSize = 16384;
 
 constexpr const char* kUsbFfsFastbootEp0 = "/dev/usb-ffs/fastboot/ep0";
 constexpr const char* kUsbFfsFastbootOut = "/dev/usb-ffs/fastboot/ep1";
diff --git a/init/Android.bp b/init/Android.bp
index 69498ac..383a69d 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -171,7 +171,6 @@
             exclude_shared_libs: ["libbinder", "libutils"],
         },
     },
-    ldflags: ["-Wl,--rpath,/system/${LIB}/bootstrap"],
 }
 
 // Tests
diff --git a/init/property_service.cpp b/init/property_service.cpp
index a1e9551..14e83f2 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -885,8 +885,12 @@
     load_properties_from_file("/system/build.prop", nullptr, &properties);
     load_properties_from_file("/vendor/default.prop", nullptr, &properties);
     load_properties_from_file("/vendor/build.prop", nullptr, &properties);
-    load_properties_from_file("/odm/default.prop", nullptr, &properties);
-    load_properties_from_file("/odm/build.prop", nullptr, &properties);
+    if (SelinuxGetVendorAndroidVersion() >= __ANDROID_API_Q__) {
+        load_properties_from_file("/odm/etc/build.prop", nullptr, &properties);
+    } else {
+        load_properties_from_file("/odm/default.prop", nullptr, &properties);
+        load_properties_from_file("/odm/build.prop", nullptr, &properties);
+    }
     load_properties_from_file("/product/build.prop", nullptr, &properties);
     load_properties_from_file("/product_services/build.prop", nullptr, &properties);
     load_properties_from_file("/factory/factory.prop", "ro.*", &properties);
diff --git a/libcutils/fs_config.cpp b/libcutils/fs_config.cpp
index 494a06f..6606030 100644
--- a/libcutils/fs_config.cpp
+++ b/libcutils/fs_config.cpp
@@ -158,8 +158,9 @@
     { 00750, AID_ROOT,      AID_SHELL,     0, "data/nativetest64/*" },
     { 00600, AID_ROOT,      AID_ROOT,      0, "default.prop" }, // legacy
     { 00600, AID_ROOT,      AID_ROOT,      0, "system/etc/prop.default" },
-    { 00600, AID_ROOT,      AID_ROOT,      0, "odm/build.prop" },
-    { 00600, AID_ROOT,      AID_ROOT,      0, "odm/default.prop" },
+    { 00600, AID_ROOT,      AID_ROOT,      0, "odm/build.prop" }, // legacy; only for P release
+    { 00600, AID_ROOT,      AID_ROOT,      0, "odm/default.prop" }, // legacy; only for P release
+    { 00600, AID_ROOT,      AID_ROOT,      0, "odm/etc/build.prop" },
     { 00444, AID_ROOT,      AID_ROOT,      0, odm_conf_dir + 1 },
     { 00444, AID_ROOT,      AID_ROOT,      0, odm_conf_file + 1 },
     { 00444, AID_ROOT,      AID_ROOT,      0, oem_conf_dir + 1 },
diff --git a/libmemunreachable/Android.bp b/libmemunreachable/Android.bp
index b78a4c4..62a7266 100644
--- a/libmemunreachable/Android.bp
+++ b/libmemunreachable/Android.bp
@@ -22,6 +22,7 @@
 
 cc_library {
     name: "libmemunreachable",
+    vendor_available: true,
     defaults: ["libmemunreachable_defaults"],
     srcs: [
         "Allocator.cpp",
@@ -48,10 +49,23 @@
     },
     export_include_dirs: ["include"],
     local_include_dirs: ["include"],
+    version_script: "libmemunreachable.map",
+}
+
+// Integration test that runs against the public API of libmemunreachable
+cc_test {
+    name: "memunreachable_test",
+    defaults: ["libmemunreachable_defaults"],
+    srcs: [
+        "tests/MemUnreachable_test.cpp",
+    ],
+    shared_libs: ["libmemunreachable"],
+
+    test_suites: ["device-tests"],
 }
 
 cc_test {
-    name: "memunreachable_test",
+    name: "memunreachable_unit_test",
     defaults: ["libmemunreachable_defaults"],
     host_supported: true,
     srcs: [
@@ -67,8 +81,9 @@
                 "tests/MemUnreachable_test.cpp",
                 "tests/ThreadCapture_test.cpp",
             ],
-            shared_libs: [
+            static_libs: [
                 "libmemunreachable",
+                "libc_malloc_debug_backtrace",
             ],
         },
         host: {
diff --git a/libmemunreachable/MemUnreachable.cpp b/libmemunreachable/MemUnreachable.cpp
index 299c320..ce937fd 100644
--- a/libmemunreachable/MemUnreachable.cpp
+++ b/libmemunreachable/MemUnreachable.cpp
@@ -280,6 +280,12 @@
 }
 
 bool GetUnreachableMemory(UnreachableMemoryInfo& info, size_t limit) {
+  if (info.version > 0) {
+    MEM_ALOGE("unsupported UnreachableMemoryInfo.version %zu in GetUnreachableMemory",
+              info.version);
+    return false;
+  }
+
   int parent_pid = getpid();
   int parent_tid = gettid();
 
diff --git a/libmemunreachable/include/memunreachable/memunreachable.h b/libmemunreachable/include/memunreachable/memunreachable.h
index c028eab..011443f 100644
--- a/libmemunreachable/include/memunreachable/memunreachable.h
+++ b/libmemunreachable/include/memunreachable/memunreachable.h
@@ -28,38 +28,45 @@
 namespace android {
 
 struct Leak {
-  uintptr_t begin;
-  size_t size;
+  uintptr_t begin = 0;
+  size_t size = 0;
 
-  size_t referenced_count;
-  size_t referenced_size;
+  size_t referenced_count = 0;
+  size_t referenced_size = 0;
 
-  size_t similar_count;
-  size_t similar_size;
-  size_t similar_referenced_count;
-  size_t similar_referenced_size;
+  size_t similar_count = 0;
+  size_t similar_size = 0;
+  size_t similar_referenced_count = 0;
+  size_t similar_referenced_size = 0;
 
-  size_t total_size;
+  size_t total_size = 0;
 
   static const size_t contents_length = 32;
-  char contents[contents_length];
+  char contents[contents_length] = {};
 
   struct Backtrace {
-    size_t num_frames;
+    size_t num_frames = 0;
 
     static const size_t max_frames = 16;
-    uintptr_t frames[max_frames];
+    uintptr_t frames[max_frames] = {};
+
+    size_t reserved[8] = {};
   } backtrace;
 
+  size_t reserved[8] = {};
+
   std::string ToString(bool log_contents) const;
 };
 
 struct UnreachableMemoryInfo {
   std::vector<Leak> leaks;
-  size_t num_leaks;
-  size_t leak_bytes;
-  size_t num_allocations;
-  size_t allocation_bytes;
+  size_t num_leaks = 0;
+  size_t leak_bytes = 0;
+  size_t num_allocations = 0;
+  size_t allocation_bytes = 0;
+
+  size_t version = 0;  // Must be 0
+  size_t reserved[8] = {};
 
   UnreachableMemoryInfo() {}
   ~UnreachableMemoryInfo();
diff --git a/libmemunreachable/libmemunreachable.map b/libmemunreachable/libmemunreachable.map
new file mode 100644
index 0000000..0d0d954
--- /dev/null
+++ b/libmemunreachable/libmemunreachable.map
@@ -0,0 +1,13 @@
+LIBMEMUNREACHABLE {
+  global:
+    LogUnreachableMemory;
+    NoLeaks;
+    extern "C++" {
+      android::GetUnreachableMemory*;
+      android::GetUnreachableMemoryString*;
+      android::Leak::*;
+      android::UnreachableMemoryInfo::*;
+    };
+  local:
+    *;
+};
diff --git a/libmemunreachable/tests/MemUnreachable_test.cpp b/libmemunreachable/tests/MemUnreachable_test.cpp
index bba0c6d..e464872 100644
--- a/libmemunreachable/tests/MemUnreachable_test.cpp
+++ b/libmemunreachable/tests/MemUnreachable_test.cpp
@@ -264,4 +264,12 @@
   ASSERT_TRUE(LogUnreachableMemory(true, 100));
 }
 
+TEST_F(MemunreachableTest, version) {
+  UnreachableMemoryInfo info;
+  info.version = 1;
+
+  ASSERT_FALSE(GetUnreachableMemory(info));
+  ASSERT_EQ(0U, info.leaks.size());
+}
+
 }  // namespace android
diff --git a/libprocessgroup/cgroup_map.cpp b/libprocessgroup/cgroup_map.cpp
index 6cd6b6e..92fcd1e 100644
--- a/libprocessgroup/cgroup_map.cpp
+++ b/libprocessgroup/cgroup_map.cpp
@@ -67,6 +67,13 @@
     return controller_ != nullptr;
 }
 
+bool CgroupController::IsUsable() const {
+    if (!HasValue()) return false;
+
+    uint32_t flags = ACgroupController_getFlags(controller_);
+    return (flags & CGROUPRC_CONTROLLER_FLAG_MOUNTED) != 0;
+}
+
 std::string CgroupController::GetTasksFilePath(const std::string& rel_path) const {
     std::string tasks_path = path();
 
@@ -153,6 +160,7 @@
         const ACgroupController* controller = ACgroupFile_getController(i);
         LOG(INFO) << "\t" << ACgroupController_getName(controller) << " ver "
                   << ACgroupController_getVersion(controller) << " path "
+                  << ACgroupController_getFlags(controller) << " flags "
                   << ACgroupController_getPath(controller);
     }
 }
diff --git a/libprocessgroup/cgroup_map.h b/libprocessgroup/cgroup_map.h
index d765e60..9350412 100644
--- a/libprocessgroup/cgroup_map.h
+++ b/libprocessgroup/cgroup_map.h
@@ -38,6 +38,7 @@
     const char* path() const;
 
     bool HasValue() const;
+    bool IsUsable() const;
 
     std::string GetTasksFilePath(const std::string& path) const;
     std::string GetProcsFilePath(const std::string& path, uid_t uid, pid_t pid) const;
diff --git a/libprocessgroup/cgrouprc/Android.bp b/libprocessgroup/cgrouprc/Android.bp
index 24652fb..0af75bb 100644
--- a/libprocessgroup/cgrouprc/Android.bp
+++ b/libprocessgroup/cgrouprc/Android.bp
@@ -43,19 +43,19 @@
         "libcgrouprc_format",
     ],
     stubs: {
-        symbol_file: "libcgrouprc.map.txt",
+        symbol_file: "libcgrouprc.llndk.txt",
         versions: ["29"],
     },
     target: {
         linux: {
-            version_script: "libcgrouprc.map.txt",
+            version_script: "libcgrouprc.llndk.txt",
         },
     },
 }
 
 llndk_library {
     name: "libcgrouprc",
-    symbol_file: "libcgrouprc.map.txt",
+    symbol_file: "libcgrouprc.llndk.txt",
     native_bridge_supported: true,
     export_include_dirs: [
         "include",
diff --git a/libprocessgroup/cgrouprc/cgroup_controller.cpp b/libprocessgroup/cgrouprc/cgroup_controller.cpp
index d064d31..5a326e5 100644
--- a/libprocessgroup/cgrouprc/cgroup_controller.cpp
+++ b/libprocessgroup/cgrouprc/cgroup_controller.cpp
@@ -27,6 +27,11 @@
     return controller->version();
 }
 
+uint32_t ACgroupController_getFlags(const ACgroupController* controller) {
+    CHECK(controller != nullptr);
+    return controller->flags();
+}
+
 const char* ACgroupController_getName(const ACgroupController* controller) {
     CHECK(controller != nullptr);
     return controller->name();
diff --git a/libprocessgroup/cgrouprc/include/android/cgrouprc.h b/libprocessgroup/cgrouprc/include/android/cgrouprc.h
index 4edd239..ffc9f0b 100644
--- a/libprocessgroup/cgrouprc/include/android/cgrouprc.h
+++ b/libprocessgroup/cgrouprc/include/android/cgrouprc.h
@@ -66,6 +66,18 @@
         __INTRODUCED_IN(29);
 
 /**
+ * Flag bitmask used in ACgroupController_getFlags
+ */
+#define CGROUPRC_CONTROLLER_FLAG_MOUNTED 0x1
+
+/**
+ * Returns the flags bitmask of the given controller.
+ * If the given controller is null, return 0.
+ */
+__attribute__((warn_unused_result)) uint32_t ACgroupController_getFlags(const ACgroupController*)
+        __INTRODUCED_IN(29);
+
+/**
  * Returns the name of the given controller.
  * If the given controller is null, return nullptr.
  */
diff --git a/libprocessgroup/cgrouprc/libcgrouprc.map.txt b/libprocessgroup/cgrouprc/libcgrouprc.llndk.txt
similarity index 88%
rename from libprocessgroup/cgrouprc/libcgrouprc.map.txt
rename to libprocessgroup/cgrouprc/libcgrouprc.llndk.txt
index 91df392..ea3df33 100644
--- a/libprocessgroup/cgrouprc/libcgrouprc.map.txt
+++ b/libprocessgroup/cgrouprc/libcgrouprc.llndk.txt
@@ -4,6 +4,7 @@
     ACgroupFile_getControllerCount;
     ACgroupFile_getController;
     ACgroupController_getVersion;
+    ACgroupController_getFlags;
     ACgroupController_getName;
     ACgroupController_getPath;
   local:
diff --git a/libprocessgroup/cgrouprc_format/cgroup_controller.cpp b/libprocessgroup/cgrouprc_format/cgroup_controller.cpp
index 877eed8..202b23e 100644
--- a/libprocessgroup/cgrouprc_format/cgroup_controller.cpp
+++ b/libprocessgroup/cgrouprc_format/cgroup_controller.cpp
@@ -20,12 +20,19 @@
 namespace cgrouprc {
 namespace format {
 
-CgroupController::CgroupController(uint32_t version, const std::string& name,
-                                   const std::string& path) {
+CgroupController::CgroupController() : version_(0), flags_(0) {
+    memset(name_, 0, sizeof(name_));
+    memset(path_, 0, sizeof(path_));
+}
+
+CgroupController::CgroupController(uint32_t version, uint32_t flags, const std::string& name,
+                                   const std::string& path)
+    : CgroupController() {
     // strlcpy isn't available on host. Although there is an implementation
     // in licutils, libcutils itself depends on libcgrouprc_format, causing
     // a circular dependency.
     version_ = version;
+    flags_ = flags;
     strncpy(name_, name.c_str(), sizeof(name_) - 1);
     name_[sizeof(name_) - 1] = '\0';
     strncpy(path_, path.c_str(), sizeof(path_) - 1);
@@ -36,6 +43,10 @@
     return version_;
 }
 
+uint32_t CgroupController::flags() const {
+    return flags_;
+}
+
 const char* CgroupController::name() const {
     return name_;
 }
@@ -44,6 +55,10 @@
     return path_;
 }
 
+void CgroupController::set_flags(uint32_t flags) {
+    flags_ = flags;
+}
+
 }  // namespace format
 }  // namespace cgrouprc
 }  // namespace android
diff --git a/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_controller.h b/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_controller.h
index 64c7532..40d8548 100644
--- a/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_controller.h
+++ b/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_controller.h
@@ -26,18 +26,23 @@
 // Minimal controller description to be mmapped into process address space
 struct CgroupController {
   public:
-    CgroupController() {}
-    CgroupController(uint32_t version, const std::string& name, const std::string& path);
+    CgroupController();
+    CgroupController(uint32_t version, uint32_t flags, const std::string& name,
+                     const std::string& path);
 
     uint32_t version() const;
+    uint32_t flags() const;
     const char* name() const;
     const char* path() const;
 
+    void set_flags(uint32_t flags);
+
   private:
     static constexpr size_t CGROUP_NAME_BUF_SZ = 16;
     static constexpr size_t CGROUP_PATH_BUF_SZ = 32;
 
     uint32_t version_;
+    uint32_t flags_;
     char name_[CGROUP_NAME_BUF_SZ];
     char path_[CGROUP_PATH_BUF_SZ];
 };
diff --git a/libprocessgroup/processgroup.cpp b/libprocessgroup/processgroup.cpp
index 1485ae9..d3ac26b 100644
--- a/libprocessgroup/processgroup.cpp
+++ b/libprocessgroup/processgroup.cpp
@@ -106,8 +106,7 @@
 }
 
 static bool isMemoryCgroupSupported() {
-    std::string cgroup_name;
-    static bool memcg_supported = CgroupMap::GetInstance().FindController("memory").HasValue();
+    static bool memcg_supported = CgroupMap::GetInstance().FindController("memory").IsUsable();
 
     return memcg_supported;
 }
diff --git a/libprocessgroup/sched_policy.cpp b/libprocessgroup/sched_policy.cpp
index fe4f93b..15f8139 100644
--- a/libprocessgroup/sched_policy.cpp
+++ b/libprocessgroup/sched_policy.cpp
@@ -151,19 +151,19 @@
 }
 
 bool cpusets_enabled() {
-    static bool enabled = (CgroupMap::GetInstance().FindController("cpuset").HasValue());
+    static bool enabled = (CgroupMap::GetInstance().FindController("cpuset").IsUsable());
     return enabled;
 }
 
 bool schedboost_enabled() {
-    static bool enabled = (CgroupMap::GetInstance().FindController("schedtune").HasValue());
+    static bool enabled = (CgroupMap::GetInstance().FindController("schedtune").IsUsable());
     return enabled;
 }
 
 static int getCGroupSubsys(int tid, const char* subsys, std::string& subgroup) {
     auto controller = CgroupMap::GetInstance().FindController(subsys);
 
-    if (!controller.HasValue()) return -1;
+    if (!controller.IsUsable()) return -1;
 
     if (!controller.GetTaskGroup(tid, &subgroup)) {
         LOG(ERROR) << "Failed to find cgroup for tid " << tid;
diff --git a/libprocessgroup/setup/cgroup_descriptor.h b/libprocessgroup/setup/cgroup_descriptor.h
index 597060e..f029c4f 100644
--- a/libprocessgroup/setup/cgroup_descriptor.h
+++ b/libprocessgroup/setup/cgroup_descriptor.h
@@ -32,6 +32,8 @@
     std::string uid() const { return uid_; }
     std::string gid() const { return gid_; }
 
+    void set_mounted(bool mounted);
+
   private:
     format::CgroupController controller_;
     mode_t mode_ = 0;
diff --git a/libprocessgroup/setup/cgroup_map_write.cpp b/libprocessgroup/setup/cgroup_map_write.cpp
index da60948..17ea06e 100644
--- a/libprocessgroup/setup/cgroup_map_write.cpp
+++ b/libprocessgroup/setup/cgroup_map_write.cpp
@@ -35,6 +35,7 @@
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
+#include <android/cgrouprc.h>
 #include <json/reader.h>
 #include <json/value.h>
 #include <processgroup/format/cgroup_file.h>
@@ -267,7 +268,17 @@
 CgroupDescriptor::CgroupDescriptor(uint32_t version, const std::string& name,
                                    const std::string& path, mode_t mode, const std::string& uid,
                                    const std::string& gid)
-    : controller_(version, name, path), mode_(mode), uid_(uid), gid_(gid) {}
+    : controller_(version, 0, name, path), mode_(mode), uid_(uid), gid_(gid) {}
+
+void CgroupDescriptor::set_mounted(bool mounted) {
+    uint32_t flags = controller_.flags();
+    if (mounted) {
+        flags |= CGROUPRC_CONTROLLER_FLAG_MOUNTED;
+    } else {
+        flags &= ~CGROUPRC_CONTROLLER_FLAG_MOUNTED;
+    }
+    controller_.set_flags(flags);
+}
 
 }  // namespace cgrouprc
 }  // namespace android
@@ -296,10 +307,11 @@
     }
 
     // setup cgroups
-    for (const auto& [name, descriptor] : descriptors) {
-        if (!SetupCgroup(descriptor)) {
+    for (auto& [name, descriptor] : descriptors) {
+        if (SetupCgroup(descriptor)) {
+            descriptor.set_mounted(true);
+        } else {
             // issue a warning and proceed with the next cgroup
-            // TODO: mark the descriptor as invalid and skip it in WriteRcFile()
             LOG(WARNING) << "Failed to setup " << name << " cgroup";
         }
     }
diff --git a/libziparchive/include/ziparchive/zip_archive.h b/libziparchive/include/ziparchive/zip_archive.h
index 7eead7e..a56a4a2 100644
--- a/libziparchive/include/ziparchive/zip_archive.h
+++ b/libziparchive/include/ziparchive/zip_archive.h
@@ -25,6 +25,7 @@
 #include <sys/cdefs.h>
 #include <sys/types.h>
 
+#include <string>
 #include <string_view>
 
 #include "android-base/off64_t.h"
@@ -35,6 +36,7 @@
   kCompressDeflated = 8,  // standard deflate
 };
 
+// TODO: remove this when everyone's moved over to std::string.
 struct ZipString {
   const uint8_t* name;
   uint16_t name_length;
@@ -180,9 +182,6 @@
 int32_t StartIteration(ZipArchiveHandle archive, void** cookie_ptr,
                        const std::string_view optional_prefix = "",
                        const std::string_view optional_suffix = "");
-// TODO: remove this.
-int32_t StartIteration(ZipArchiveHandle archive, void** cookie_ptr,
-                       const ZipString* optional_prefix, const ZipString* optional_suffix);
 
 /*
  * Advance to the next element in the zipfile in iteration order.
@@ -190,6 +189,8 @@
  * Returns 0 on success, -1 if there are no more elements in this
  * archive and lower negative values on failure.
  */
+int32_t Next(void* cookie, ZipEntry* data, std::string* name);
+// TODO: remove this when everyone's moved over to std::string.
 int32_t Next(void* cookie, ZipEntry* data, ZipString* name);
 
 /*
diff --git a/libziparchive/unzip.cpp b/libziparchive/unzip.cpp
index 3a3a694..426325e 100644
--- a/libziparchive/unzip.cpp
+++ b/libziparchive/unzip.cpp
@@ -255,9 +255,8 @@
   }
 
   ZipEntry entry;
-  ZipString string;
-  while ((err = Next(cookie, &entry, &string)) >= 0) {
-    std::string name(string.name, string.name + string.name_length);
+  std::string name;
+  while ((err = Next(cookie, &entry, &name)) >= 0) {
     if (ShouldInclude(name)) ProcessOne(zah, entry, name);
   }
 
diff --git a/libziparchive/zip_archive.cc b/libziparchive/zip_archive.cc
index ac3e236..f4b6c74 100644
--- a/libziparchive/zip_archive.cc
+++ b/libziparchive/zip_archive.cc
@@ -726,22 +726,6 @@
   return 0;
 }
 
-// TODO: remove this.
-int32_t StartIteration(ZipArchiveHandle archive, void** cookie_ptr,
-                       const ZipString* optional_prefix, const ZipString* optional_suffix) {
-  std::string prefix;
-  if (optional_prefix) {
-    prefix = std::string(reinterpret_cast<const char*>(optional_prefix->name),
-                         optional_prefix->name_length);
-  }
-  std::string suffix;
-  if (optional_suffix) {
-    suffix = std::string(reinterpret_cast<const char*>(optional_suffix->name),
-                         optional_suffix->name_length);
-  }
-  return StartIteration(archive, cookie_ptr, prefix.c_str(), suffix.c_str());
-}
-
 void EndIteration(void* cookie) {
   delete reinterpret_cast<IterationHandle*>(cookie);
 }
@@ -763,6 +747,15 @@
   return FindEntry(archive, static_cast<uint32_t>(ent), data);
 }
 
+int32_t Next(void* cookie, ZipEntry* data, std::string* name) {
+  ZipString zs;
+  int32_t result = Next(cookie, data, &zs);
+  if (result == 0) {
+    *name = std::string(reinterpret_cast<const char*>(zs.name), zs.name_length);
+  }
+  return result;
+}
+
 int32_t Next(void* cookie, ZipEntry* data, ZipString* name) {
   IterationHandle* handle = reinterpret_cast<IterationHandle*>(cookie);
   if (handle == NULL) {
diff --git a/libziparchive/zip_archive_benchmark.cpp b/libziparchive/zip_archive_benchmark.cpp
index 434f2e1..23ed408 100644
--- a/libziparchive/zip_archive_benchmark.cpp
+++ b/libziparchive/zip_archive_benchmark.cpp
@@ -71,7 +71,7 @@
   ZipArchiveHandle handle;
   void* iteration_cookie;
   ZipEntry data;
-  ZipString name;
+  std::string name;
 
   while (state.KeepRunning()) {
     OpenArchive(temp_file->path, &handle);
diff --git a/libziparchive/zip_archive_test.cc b/libziparchive/zip_archive_test.cc
index 993c975..b6ca9ec 100644
--- a/libziparchive/zip_archive_test.cc
+++ b/libziparchive/zip_archive_test.cc
@@ -118,10 +118,10 @@
   ZipEntry data;
   std::vector<std::string> names;
 
-  ZipString name;
+  std::string name;
   for (size_t i = 0; i < expected_names_sorted.size(); ++i) {
     ASSERT_EQ(0, Next(iteration_cookie, &data, &name));
-    names.push_back(std::string(reinterpret_cast<const char*>(name.name), name.name_length));
+    names.push_back(name);
   }
 
   // End of iteration.
@@ -167,7 +167,7 @@
   ASSERT_EQ(0, StartIteration(handle, &iteration_cookie, "x", "y"));
 
   ZipEntry data;
-  ZipString name;
+  std::string name;
 
   // End of iteration.
   ASSERT_EQ(-1, Next(iteration_cookie, &data, &name));
@@ -224,7 +224,7 @@
   void* iteration_cookie;
   ASSERT_EQ(0, StartIteration(handle, &iteration_cookie));
 
-  ZipString name;
+  std::string name;
   ZipEntry data;
 
   ASSERT_EQ(Next(iteration_cookie, &data, &name), 0);