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/*
*
* Copyright (c) 2020 Project CHIP Authors
* Copyright (c) 2016-2017 Nest Labs, Inc.
*
* 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.
*/
/**
* @file
*
* @brief
* API function declarations for reading from and writing to persistent storage.
* Platforms will be responsible for implementing the read/write details.
*/
#pragma once
#include <climits>
#include <cstddef>
#include <cstdint>
#include <type_traits>
#include <lib/core/CHIPConfig.h>
#include <lib/core/CHIPError.h>
namespace chip {
namespace Platform {
namespace PersistedStorage {
// Persistent storage key type is const char * in core config, however
// it is uint8_t/uint16_t on other platforms (EFR32 and nRF5 respectively)
typedef CHIP_CONFIG_PERSISTED_STORAGE_KEY_TYPE Key;
namespace internal {
template <typename T>
struct EmptyKey
{
static constexpr T value = 0; // handles numeric values
};
template <>
struct EmptyKey<const char *>
{
static constexpr const char * value = nullptr;
};
} // namespace internal
inline constexpr Key kEmptyKey = internal::EmptyKey<Key>::value;
/**
* @brief
* Read integer value of a key from persistent storage.
* Platform is responsible for validating aKey.
*
* @param[in] aKey A key to a persistently-stored value.
* @param[in,out] aValue A reference to an integer value.
*
* @return CHIP_ERROR_INVALID_ARGUMENT if aKey is NULL
* CHIP_ERROR_INVALID_STRING_LENGTH if aKey exceeds
* CHIP_CONFIG_PERSISTED_STORAGE_MAX_KEY_LENGTH
* CHIP_ERROR_PERSISTED_STORAGE_VALUE_NOT_FOUND if aKey does not exist
* CHIP_NO_ERROR otherwise
*/
CHIP_ERROR Read(Key aKey, uint32_t & aValue);
/**
* @brief
* Write the integer value of a key to persistent storage.
* Platform is responsible for validating aKey.
* If aKey does not exist, it will be created and assigned aValue.
* Otherwise any existing value of aKey will be replaced with aValue.
*
* @param[in] aKey A key to a persistently-stored value.
* @param[in] aValue The value.
*
* @return CHIP_ERROR_INVALID_ARGUMENT if aKey is NULL
* CHIP_ERROR_INVALID_STRING_LENGTH if aKey exceeds
* CHIP_CONFIG_PERSISTED_STORAGE_MAX_KEY_LENGTH
* CHIP_NO_ERROR otherwise
*/
CHIP_ERROR Write(Key aKey, uint32_t aValue);
} // namespace PersistedStorage
} // namespace Platform
} // namespace chip