base/properties.cpp

/*
 * 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