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Commit 1e88c8c0 authored by Elliott Hughes's avatar Elliott Hughes
Browse files

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
parent efee71c2

base/Android.bp

+7 −1
Original line number Diff line number Diff line
@@ -39,7 +39,10 @@ cc_library { 
    shared_libs: ["liblog"],

    target: {

        android: {

            srcs: ["errors_unix.cpp"],

            srcs: [

                "errors_unix.cpp",

                "properties.cpp",

            ],

            cppflags: ["-Wexit-time-destructors"],

        },

        darwin: {
@@ -78,6 +81,9 @@ cc_test { 
        "test_main.cpp",

    ],

    target: {

        android: {

            srcs: ["properties_test.cpp"],

        },

        windows: {

            srcs: ["utf8_test.cpp"],

            enabled: true,

base/include/android-base/properties.h

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+64 −0
Original line number Diff line number Diff line 
/*

 * 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.

 */



#ifndef ANDROID_BASE_PROPERTIES_H

#define ANDROID_BASE_PROPERTIES_H



#include <sys/cdefs.h>



#if !defined(__BIONIC__)

#error Only bionic supports system properties.

#endif



#include <limits>

#include <string>



namespace android {

namespace base {



// Returns the current value of the system property `key`,

// or `default_value` if the property is empty or doesn't exist.

std::string GetProperty(const std::string& key, const std::string& default_value);



// Returns true if the system property `key` has the value "1", "y", "yes", "on", or "true",

// false for "0", "n", "no", "off", or "false", or `default_value` otherwise.

bool GetBoolProperty(const std::string& key, bool default_value);



// Returns the signed integer corresponding to the system property `key`.

// If the property is empty, doesn't exist, doesn't have an integer value, or is outside

// the optional bounds, returns `default_value`.

template <typename T> T GetIntProperty(const std::string& key,

                                       T default_value,

                                       T min = std::numeric_limits<T>::min(),

                                       T max = std::numeric_limits<T>::max());



// Returns the unsigned integer corresponding to the system property `key`.

// If the property is empty, doesn't exist, doesn't have an integer value, or is outside

// the optional bound, returns `default_value`.

template <typename T> T GetUintProperty(const std::string& key,

                                        T default_value,

                                        T max = std::numeric_limits<T>::max());



// Sets the system property `key` to `value`.

// Note that system property setting is inherently asynchronous so a return value of `true`

// isn't particularly meaningful, and immediately reading back the value won't necessarily

// tell you whether or not your call succeeded. A `false` return value definitely means failure.

bool SetProperty(const std::string& key, const std::string& value);



} // namespace base

} // namespace android



#endif  // ANDROID_BASE_MEMORY_H

base/properties.cpp

0 → 100644
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/*

 * 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 <sys/system_properties.h>



#include <string>



#include <android-base/parseint.h>



namespace android {

namespace base {



std::string GetProperty(const std::string& key, const std::string& default_value) {

  const prop_info* pi = __system_property_find(key.c_str());

  if (pi == nullptr) return default_value;



  char buf[PROP_VALUE_MAX];

  if (__system_property_read(pi, nullptr, buf) > 0) return buf;



  // If the property exists but is empty, also return the default value.

  // Since we can't remove system properties, "empty" is traditionally

  // the same as "missing" (this was true for cutils' property_get).

  return default_value;

}



bool GetBoolProperty(const std::string& key, bool default_value) {

  std::string value = GetProperty(key, "");

  if (value == "1" || value == "y" || value == "yes" || value == "on" || value == "true") {

    return true;

  } else if (value == "0" || value == "n" || value == "no" || value == "off" || value == "false") {

    return false;

  }

  return default_value;

}



template <typename T>

T GetIntProperty(const std::string& key, T default_value, T min, T max) {

  T result;

  std::string value = GetProperty(key, "");

  if (!value.empty() && android::base::ParseInt(value.c_str(), &result, min, max)) return result;

  return default_value;

}



template <typename T>

T GetUintProperty(const std::string& key, T default_value, T max) {

  T result;

  std::string value = GetProperty(key, "");

  if (!value.empty() && android::base::ParseUint(value.c_str(), &result, max)) return result;

  return default_value;

}



template int8_t GetIntProperty(const std::string&, int8_t, int8_t, int8_t);

template int16_t GetIntProperty(const std::string&, int16_t, int16_t, int16_t);

template int32_t GetIntProperty(const std::string&, int32_t, int32_t, int32_t);

template int64_t GetIntProperty(const std::string&, int64_t, int64_t, int64_t);



template uint8_t GetUintProperty(const std::string&, uint8_t, uint8_t);

template uint16_t GetUintProperty(const std::string&, uint16_t, uint16_t);

template uint32_t GetUintProperty(const std::string&, uint32_t, uint32_t);

template uint64_t GetUintProperty(const std::string&, uint64_t, uint64_t);



bool SetProperty(const std::string& key, const std::string& value) {

  return (__system_property_set(key.c_str(), value.c_str()) == 0);

}



}  // namespace base

}  // namespace android

base/properties_test.cpp

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/*

 * 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>(); }