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/*
* Copyright (C) 2022 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 ART_LIBARTTOOLS_INCLUDE_TOOLS_SYSTEM_PROPERTIES_H_
#define ART_LIBARTTOOLS_INCLUDE_TOOLS_SYSTEM_PROPERTIES_H_
#include <string>
#include "android-base/parsebool.h"
#include "android-base/properties.h"
namespace art {
namespace tools {
// A class for getting system properties with fallback lookup support. Different from
// android::base::GetProperty, this class is mockable.
class SystemProperties {
public:
SystemProperties() = default;
SystemProperties(const SystemProperties& other) = default;
SystemProperties& operator=(const SystemProperties& other) = default;
SystemProperties(SystemProperties&& other) = default;
SystemProperties& operator=(SystemProperties&& other) = default;
virtual ~SystemProperties() = default;
// Returns the current value of the system property `key`, or `default_value` if the property
// doesn't have a value.
std::string Get(const std::string& key, const std::string& default_value) const {
std::string value = GetProperty(key);
if (!value.empty()) {
return value;
}
return default_value;
}
// Same as above, but allows specifying one or more fallback keys. The last argument is a string
// default value that will be used if none of the given keys has a value.
//
// Usage:
//
// Look up for "key_1", then "key_2", then "key_3". If none of them has a value, return "default":
// Get("key_1", "key_2", "key_3", /*default_value=*/"default")
template <typename... Args>
std::string Get(const std::string& key, const std::string& fallback_key, Args... args) const {
return Get(key, Get(fallback_key, args...));
}
// Returns the current value of the system property `key` with zero or more fallback keys, or an
// empty string if none of the given keys has a value.
//
// Usage:
//
// Look up for "key_1". If it doesn't have a value, return an empty string:
// GetOrEmpty("key_1")
//
// Look up for "key_1", then "key_2", then "key_3". If none of them has a value, return an empty
// string:
// GetOrEmpty("key_1", "key_2", "key_3")
template <typename... Args>
std::string GetOrEmpty(const std::string& key, Args... fallback_keys) const {
return Get(key, fallback_keys..., /*default_value=*/"");
}
// Returns the current value of the boolean system property `key`, or `default_value` if the
// property doesn't have a value. See `android::base::ParseBool` for how the value is parsed.
bool GetBool(const std::string& key, bool default_value) const {
android::base::ParseBoolResult result = android::base::ParseBool(GetProperty(key));
if (result != android::base::ParseBoolResult::kError) {
return result == android::base::ParseBoolResult::kTrue;
}
return default_value;
}
// Same as above, but allows specifying one or more fallback keys. The last argument is a bool
// default value that will be used if none of the given keys has a value.
//
// Usage:
//
// Look up for "key_1", then "key_2", then "key_3". If none of them has a value, return true:
// Get("key_1", "key_2", "key_3", /*default_value=*/true)
template <typename... Args>
bool GetBool(const std::string& key, const std::string& fallback_key, Args... args) const {
return GetBool(key, GetBool(fallback_key, args...));
}
protected:
// The single source of truth of system properties. Can be mocked in unit tests.
virtual std::string GetProperty(const std::string& key) const {
return android::base::GetProperty(key, /*default_value=*/"");
}
};
} // namespace tools
} // namespace art
#endif // ART_LIBARTTOOLS_INCLUDE_TOOLS_SYSTEM_PROPERTIES_H_
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