Add std::string system property functions.

Makes it easier to write correct code in a world where the maximum
property key/value lengths change.

Bug: http://b/23102347
Test: libbase_test64
Change-Id: I100f00904221bbcef9e8786a4e6e30428039bb49
diff --git a/properties_test.cpp b/properties_test.cpp
new file mode 100644
index 0000000..da89ec5
--- /dev/null
+++ b/properties_test.cpp
@@ -0,0 +1,121 @@
+/*
+ * Copyright (C) 2016 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/properties.h"
+
+#include <gtest/gtest.h>
+
+#include <string>
+
+TEST(properties, smoke) {
+  android::base::SetProperty("debug.libbase.property_test", "hello");
+
+  std::string s = android::base::GetProperty("debug.libbase.property_test", "");
+  ASSERT_EQ("hello", s);
+
+  android::base::SetProperty("debug.libbase.property_test", "world");
+  s = android::base::GetProperty("debug.libbase.property_test", "");
+  ASSERT_EQ("world", s);
+
+  s = android::base::GetProperty("this.property.does.not.exist", "");
+  ASSERT_EQ("", s);
+
+  s = android::base::GetProperty("this.property.does.not.exist", "default");
+  ASSERT_EQ("default", s);
+}
+
+TEST(properties, empty) {
+  // Because you can't delete a property, people "delete" them by
+  // setting them to the empty string. In that case we'd want to
+  // keep the default value (like cutils' property_get did).
+  android::base::SetProperty("debug.libbase.property_test", "");
+  std::string s = android::base::GetProperty("debug.libbase.property_test", "default");
+  ASSERT_EQ("default", s);
+}
+
+static void CheckGetBoolProperty(bool expected, const std::string& value, bool default_value) {
+  android::base::SetProperty("debug.libbase.property_test", value.c_str());
+  ASSERT_EQ(expected, android::base::GetBoolProperty("debug.libbase.property_test", default_value));
+}
+
+TEST(properties, GetBoolProperty_true) {
+  CheckGetBoolProperty(true, "1", false);
+  CheckGetBoolProperty(true, "y", false);
+  CheckGetBoolProperty(true, "yes", false);
+  CheckGetBoolProperty(true, "on", false);
+  CheckGetBoolProperty(true, "true", false);
+}
+
+TEST(properties, GetBoolProperty_false) {
+  CheckGetBoolProperty(false, "0", true);
+  CheckGetBoolProperty(false, "n", true);
+  CheckGetBoolProperty(false, "no", true);
+  CheckGetBoolProperty(false, "off", true);
+  CheckGetBoolProperty(false, "false", true);
+}
+
+TEST(properties, GetBoolProperty_default) {
+  CheckGetBoolProperty(true, "burp", true);
+  CheckGetBoolProperty(false, "burp", false);
+}
+
+template <typename T> void CheckGetIntProperty() {
+  // Positive and negative.
+  android::base::SetProperty("debug.libbase.property_test", "-12");
+  EXPECT_EQ(T(-12), android::base::GetIntProperty<T>("debug.libbase.property_test", 45));
+  android::base::SetProperty("debug.libbase.property_test", "12");
+  EXPECT_EQ(T(12), android::base::GetIntProperty<T>("debug.libbase.property_test", 45));
+
+  // Default value.
+  android::base::SetProperty("debug.libbase.property_test", "");
+  EXPECT_EQ(T(45), android::base::GetIntProperty<T>("debug.libbase.property_test", 45));
+
+  // Bounds checks.
+  android::base::SetProperty("debug.libbase.property_test", "0");
+  EXPECT_EQ(T(45), android::base::GetIntProperty<T>("debug.libbase.property_test", 45, 1, 2));
+  android::base::SetProperty("debug.libbase.property_test", "1");
+  EXPECT_EQ(T(1), android::base::GetIntProperty<T>("debug.libbase.property_test", 45, 1, 2));
+  android::base::SetProperty("debug.libbase.property_test", "2");
+  EXPECT_EQ(T(2), android::base::GetIntProperty<T>("debug.libbase.property_test", 45, 1, 2));
+  android::base::SetProperty("debug.libbase.property_test", "3");
+  EXPECT_EQ(T(45), android::base::GetIntProperty<T>("debug.libbase.property_test", 45, 1, 2));
+}
+
+template <typename T> void CheckGetUintProperty() {
+  // Positive.
+  android::base::SetProperty("debug.libbase.property_test", "12");
+  EXPECT_EQ(T(12), android::base::GetUintProperty<T>("debug.libbase.property_test", 45));
+
+  // Default value.
+  android::base::SetProperty("debug.libbase.property_test", "");
+  EXPECT_EQ(T(45), android::base::GetUintProperty<T>("debug.libbase.property_test", 45));
+
+  // Bounds checks.
+  android::base::SetProperty("debug.libbase.property_test", "12");
+  EXPECT_EQ(T(12), android::base::GetUintProperty<T>("debug.libbase.property_test", 33, 22));
+  android::base::SetProperty("debug.libbase.property_test", "12");
+  EXPECT_EQ(T(5), android::base::GetUintProperty<T>("debug.libbase.property_test", 5, 10));
+}
+
+TEST(properties, GetIntProperty_int8_t) { CheckGetIntProperty<int8_t>(); }
+TEST(properties, GetIntProperty_int16_t) { CheckGetIntProperty<int16_t>(); }
+TEST(properties, GetIntProperty_int32_t) { CheckGetIntProperty<int32_t>(); }
+TEST(properties, GetIntProperty_int64_t) { CheckGetIntProperty<int64_t>(); }
+
+TEST(properties, GetUintProperty_uint8_t) { CheckGetUintProperty<uint8_t>(); }
+TEST(properties, GetUintProperty_uint16_t) { CheckGetUintProperty<uint16_t>(); }
+TEST(properties, GetUintProperty_uint32_t) { CheckGetUintProperty<uint32_t>(); }
+TEST(properties, GetUintProperty_uint64_t) { CheckGetUintProperty<uint64_t>(); }