src/platform/silabs/KeyValueStoreManagerImpl.cpp - third_party/github/project-chip/connectedhomeip - Git at Google

 /*
  *
  *    Copyright (c) 2021-2022 Project CHIP Authors
  *    All rights reserved.
  *
  *    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
  *          Platform-specific key value storage implementation for SILABS
  */

 #include "MigrationManager.h"
 #include <crypto/CHIPCryptoPAL.h>
 #include <platform/CHIPDeviceLayer.h>
 #include <platform/KeyValueStoreManager.h>
 #include <platform/silabs/SilabsConfig.h>
 #include <stdio.h>
 #include <string.h>

 using namespace ::chip;
 using namespace ::chip::Crypto;
 using namespace ::chip::DeviceLayer::Internal;

 #define CONVERT_KEYMAP_INDEX_TO_NVM3KEY(index) (SilabsConfig::kConfigKey_KvsFirstKeySlot + index)
 #define CONVERT_NVM3KEY_TO_KEYMAP_INDEX(nvm3Key) (nvm3Key - SilabsConfig::kConfigKey_KvsFirstKeySlot)

 namespace chip {
 namespace DeviceLayer {
 namespace PersistedStorage {

 KeyValueStoreManagerImpl KeyValueStoreManagerImpl::sInstance;
 uint16_t mKvsKeyMap[KeyValueStoreManagerImpl::kMaxEntries] = { 0 };

 CHIP_ERROR KeyValueStoreManagerImpl::Init(void)
 {
     CHIP_ERROR err;
     err = SilabsConfig::Init();
     SuccessOrExit(err);

     Silabs::MigrationManager::GetMigrationInstance().applyMigrations();

     memset(mKvsKeyMap, 0, sizeof(mKvsKeyMap));
     size_t outLen;
     err = SilabsConfig::ReadConfigValueBin(SilabsConfig::kConfigKey_KvsStringKeyMap, reinterpret_cast<uint8_t *>(mKvsKeyMap),
                                            sizeof(mKvsKeyMap), outLen);

     if (err == CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND) // Initial boot
     {
         err = CHIP_NO_ERROR;
     }

 exit:
     return err;
 }

 bool KeyValueStoreManagerImpl::IsValidKvsNvm3Key(uint32_t nvm3Key) const
 {
     return ((SilabsConfig::kConfigKey_KvsFirstKeySlot <= nvm3Key) && (nvm3Key <= SilabsConfig::kConfigKey_KvsLastKeySlot));
 }

 uint16_t KeyValueStoreManagerImpl::hashKvsKeyString(const char * key) const
 {
     uint8_t hash256[Crypto::kSHA256_Hash_Length] = { 0 };
     Crypto::Hash_SHA256(reinterpret_cast<const uint8_t *>(key), strlen(key), hash256);

     uint16_t hash16 = 0, i = 0;

     while (!hash16 && (i < (Crypto::kSHA256_Hash_Length - 1)))
     {
         hash16 = (hash256[i] | (hash256[i + 1] << 8));
         i++;
     }
     return hash16;
 }

 CHIP_ERROR KeyValueStoreManagerImpl::MapKvsKeyToNvm3(const char * key, uint16_t hash, uint32_t & nvm3Key, bool isSlotNeeded) const
 {
     CHIP_ERROR err;
     char * strPrefix          = nullptr;
     uint8_t firstEmptyKeySlot = kMaxEntries;
     for (uint8_t keyIndex = 0; keyIndex < kMaxEntries; keyIndex++)
     {
         if (mKvsKeyMap[keyIndex] == hash)
         {
             uint32_t tempNvm3key = CONVERT_KEYMAP_INDEX_TO_NVM3KEY(keyIndex);
             VerifyOrDie(IsValidKvsNvm3Key(tempNvm3key) == true);

             size_t readCount;
             size_t length = strlen(key);
             if (strPrefix == nullptr)
             {
                 // Use a calloc to initialize all bits to 0. alloc +1 for a null char
                 strPrefix = static_cast<char *>(Platform::MemoryCalloc(1, length + 1));
                 VerifyOrDie(strPrefix != nullptr);
             }

             // Collision prevention
             // Read the data from NVM3 it should be prefixed by the kvsString
             // else we will look for another matching hash in the map
             SilabsConfig::ReadConfigValueBin(tempNvm3key, reinterpret_cast<uint8_t *>(strPrefix), length, readCount, 0);
             if (strcmp(key, strPrefix) == 0)
             {
                 // String matches we have confirmed the hash pointed us the right key data
                 nvm3Key = tempNvm3key;
                 Platform::MemoryFree(strPrefix);
                 return CHIP_NO_ERROR;
             }
         }

         if (isSlotNeeded && (firstEmptyKeySlot == kMaxEntries) && (mKvsKeyMap[keyIndex] == 0))
         {
             firstEmptyKeySlot = keyIndex;
         }
     }

     Platform::MemoryFree(strPrefix);

     if (isSlotNeeded)
     {
         if (firstEmptyKeySlot != kMaxEntries)
         {
             nvm3Key = CONVERT_KEYMAP_INDEX_TO_NVM3KEY(firstEmptyKeySlot);
             VerifyOrDie(IsValidKvsNvm3Key(nvm3Key) == true);
             err = CHIP_NO_ERROR;
         }
         else
         {
             err = CHIP_ERROR_PERSISTED_STORAGE_FAILED;
         }
     }
     else
     {
         err = CHIP_ERROR_PERSISTED_STORAGE_VALUE_NOT_FOUND;
     }
     return err;
 }

 void KeyValueStoreManagerImpl::ForceKeyMapSave()
 {
     OnScheduledKeyMapSave(nullptr, nullptr);
 }

 void KeyValueStoreManagerImpl::OnScheduledKeyMapSave(System::Layer * systemLayer, void * appState)
 {
     SilabsConfig::WriteConfigValueBin(SilabsConfig::kConfigKey_KvsStringKeyMap, reinterpret_cast<const uint8_t *>(mKvsKeyMap),
                                       sizeof(mKvsKeyMap));
 }

 void KeyValueStoreManagerImpl::ScheduleKeyMapSave(void)
 {
     /*
         During commissioning, the key map will be modified multiples times subsequently.
         Commit the key map in nvm once it as stabilized.
     */
     SystemLayer().StartTimer(
         std::chrono::duration_cast<System::Clock::Timeout>(System::Clock::Seconds32(SILABS_KVS_SAVE_DELAY_SECONDS)),
         KeyValueStoreManagerImpl::OnScheduledKeyMapSave, NULL);
 }

 CHIP_ERROR KeyValueStoreManagerImpl::_Get(const char * key, void * value, size_t value_size, size_t * read_bytes_size,
                                           size_t offset_bytes) const
 {
     VerifyOrReturnError(key != nullptr, CHIP_ERROR_INVALID_ARGUMENT);

     uint32_t nvm3Key;
     uint16_t hash  = hashKvsKeyString(key);
     CHIP_ERROR err = MapKvsKeyToNvm3(key, hash, nvm3Key);
     VerifyOrReturnError(err == CHIP_NO_ERROR, err);

     size_t outLen;
     // The user doesn't need the KeyString prefix, Read data after it
     size_t KeyStringLen = strlen(key);
     err                 = SilabsConfig::ReadConfigValueBin(nvm3Key, reinterpret_cast<uint8_t *>(value), value_size, outLen,
                                            (offset_bytes + KeyStringLen));
     if (read_bytes_size)
     {
         *read_bytes_size = outLen;
     }

     if (err == CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND)
     {
         return CHIP_ERROR_PERSISTED_STORAGE_VALUE_NOT_FOUND;
     }

     return err;
 }

 CHIP_ERROR KeyValueStoreManagerImpl::_Put(const char * key, const void * value, size_t value_size)
 {
     VerifyOrReturnError(key != nullptr, CHIP_ERROR_INVALID_ARGUMENT);

     uint32_t nvm3Key;
     uint16_t hash  = hashKvsKeyString(key);
     CHIP_ERROR err = MapKvsKeyToNvm3(key, hash, nvm3Key, /* isSlotNeeded */ true);
     VerifyOrReturnError(err == CHIP_NO_ERROR, err);

     // add the string Key as prefix to the stored data as a collision prevention mechanism.
     size_t keyStringLen    = strlen(key);
     uint8_t * prefixedData = static_cast<uint8_t *>(Platform::MemoryAlloc(keyStringLen + value_size));
     VerifyOrDie(prefixedData != nullptr);
     memcpy(prefixedData, key, keyStringLen);
     memcpy(prefixedData + keyStringLen, value, value_size);

     err = SilabsConfig::WriteConfigValueBin(nvm3Key, prefixedData, keyStringLen + value_size);
     if (err == CHIP_NO_ERROR)
     {
         uint32_t keyIndex    = CONVERT_NVM3KEY_TO_KEYMAP_INDEX(nvm3Key);
         mKvsKeyMap[keyIndex] = hash;
         ScheduleKeyMapSave();
     }
     Platform::MemoryFree(prefixedData);
     return err;
 }

 CHIP_ERROR KeyValueStoreManagerImpl::_Delete(const char * key)
 {
     VerifyOrReturnError(key != nullptr, CHIP_ERROR_INVALID_ARGUMENT);

     uint32_t nvm3Key;
     uint16_t hash  = hashKvsKeyString(key);
     CHIP_ERROR err = MapKvsKeyToNvm3(key, hash, nvm3Key);
     VerifyOrReturnError(err == CHIP_NO_ERROR, err);

     err = SilabsConfig::ClearConfigValue(nvm3Key);
     if (err == CHIP_NO_ERROR)
     {
         uint32_t keyIndex    = CONVERT_NVM3KEY_TO_KEYMAP_INDEX(nvm3Key);
         mKvsKeyMap[keyIndex] = 0;
         ScheduleKeyMapSave();
     }

     return err;
 }

 void KeyValueStoreManagerImpl::ErasePartition(void)
 {
     // Iterate over all the Matter Kvs nvm3 records and delete each one...
     for (uint32_t nvm3Key = SilabsConfig::kMinConfigKey_MatterKvs; nvm3Key <= SilabsConfig::kMaxConfigKey_MatterKvs; nvm3Key++)
     {
         SilabsConfig::ClearConfigValue(nvm3Key);
     }

     memset(mKvsKeyMap, 0, sizeof(mKvsKeyMap));
 }

 void KeyValueStoreManagerImpl::KvsMapMigration(void)
 {
     size_t readlen                                                                        = 0;
     constexpr uint8_t oldMaxEntires                                                       = 120;
     char mKvsStoredKeyString[oldMaxEntires][PersistentStorageDelegate::kKeyLengthMax + 1] = { 0 };
     CHIP_ERROR err =
         SilabsConfig::ReadConfigValueBin(SilabsConfig::kConfigKey_KvsStringKeyMap, reinterpret_cast<uint8_t *>(mKvsStoredKeyString),
                                          sizeof(mKvsStoredKeyString), readlen);

     if (err == CHIP_NO_ERROR)
     {
         for (uint8_t i = 0; i < oldMaxEntires; i++)
         {
             if (mKvsStoredKeyString[i][0] != 0)
             {
                 size_t dataLen   = 0;
                 uint32_t nvm3Key = CONVERT_KEYMAP_INDEX_TO_NVM3KEY(i);

                 if (SilabsConfig::ConfigValueExists(nvm3Key, dataLen))
                 {
                     // Read old data and prefix it with the string Key for the collision prevention mechanism.
                     size_t keyStringLen    = strlen(mKvsStoredKeyString[i]);
                     uint8_t * prefixedData = static_cast<uint8_t *>(Platform::MemoryAlloc(keyStringLen + dataLen));
                     VerifyOrDie(prefixedData != nullptr);
                     memcpy(prefixedData, mKvsStoredKeyString[i], keyStringLen);

                     SilabsConfig::ReadConfigValueBin(nvm3Key, prefixedData + keyStringLen, dataLen, readlen);
                     SilabsConfig::WriteConfigValueBin(nvm3Key, prefixedData, keyStringLen + dataLen);
                     mKvsKeyMap[i] = KeyValueStoreMgrImpl().hashKvsKeyString(mKvsStoredKeyString[i]);
                     Platform::MemoryFree(prefixedData);
                 }
             }
         }
         ForceKeyMapSave();
     }
     else if (err != CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND)
     {
         // Error reading the old String Keymap. Cannot not resolve stored data for migration.
         ChipLogError(DeviceLayer, "Migration failed ! Kvs Key map could not be recovered %" CHIP_ERROR_FORMAT, err.Format());
         // start with a fresh kvs section.
         KeyValueStoreMgrImpl().ErasePartition();
     }
 }

 } // namespace PersistedStorage
 } // namespace DeviceLayer
 } // namespace chip
	/*
	*
	* Copyright (c) 2021-2022 Project CHIP Authors
	* All rights reserved.
	*
	* 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
	* Platform-specific key value storage implementation for SILABS
	*/

	#include "MigrationManager.h"
	#include <crypto/CHIPCryptoPAL.h>
	#include <platform/CHIPDeviceLayer.h>
	#include <platform/KeyValueStoreManager.h>
	#include <platform/silabs/SilabsConfig.h>
	#include <stdio.h>
	#include <string.h>

	using namespace ::chip;
	using namespace ::chip::Crypto;
	using namespace ::chip::DeviceLayer::Internal;

	#define CONVERT_KEYMAP_INDEX_TO_NVM3KEY(index) (SilabsConfig::kConfigKey_KvsFirstKeySlot + index)
	#define CONVERT_NVM3KEY_TO_KEYMAP_INDEX(nvm3Key) (nvm3Key - SilabsConfig::kConfigKey_KvsFirstKeySlot)

	namespace chip {
	namespace DeviceLayer {
	namespace PersistedStorage {

	KeyValueStoreManagerImpl KeyValueStoreManagerImpl::sInstance;
	uint16_t mKvsKeyMap[KeyValueStoreManagerImpl::kMaxEntries] = { 0 };

	CHIP_ERROR KeyValueStoreManagerImpl::Init(void)
	{
	CHIP_ERROR err;
	err = SilabsConfig::Init();
	SuccessOrExit(err);

	Silabs::MigrationManager::GetMigrationInstance().applyMigrations();

	memset(mKvsKeyMap, 0, sizeof(mKvsKeyMap));
	size_t outLen;
	err = SilabsConfig::ReadConfigValueBin(SilabsConfig::kConfigKey_KvsStringKeyMap, reinterpret_cast<uint8_t *>(mKvsKeyMap),
	sizeof(mKvsKeyMap), outLen);

	if (err == CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND) // Initial boot
	{
	err = CHIP_NO_ERROR;
	}

	exit:
	return err;
	}

	bool KeyValueStoreManagerImpl::IsValidKvsNvm3Key(uint32_t nvm3Key) const
	{
	return ((SilabsConfig::kConfigKey_KvsFirstKeySlot <= nvm3Key) && (nvm3Key <= SilabsConfig::kConfigKey_KvsLastKeySlot));
	}

	uint16_t KeyValueStoreManagerImpl::hashKvsKeyString(const char * key) const
	{
	uint8_t hash256[Crypto::kSHA256_Hash_Length] = { 0 };
	Crypto::Hash_SHA256(reinterpret_cast<const uint8_t *>(key), strlen(key), hash256);

	uint16_t hash16 = 0, i = 0;

	while (!hash16 && (i < (Crypto::kSHA256_Hash_Length - 1)))
	{
	hash16 = (hash256[i] \| (hash256[i + 1] << 8));
	i++;
	}
	return hash16;
	}

	CHIP_ERROR KeyValueStoreManagerImpl::MapKvsKeyToNvm3(const char * key, uint16_t hash, uint32_t & nvm3Key, bool isSlotNeeded) const
	{
	CHIP_ERROR err;
	char * strPrefix = nullptr;
	uint8_t firstEmptyKeySlot = kMaxEntries;
	for (uint8_t keyIndex = 0; keyIndex < kMaxEntries; keyIndex++)
	{
	if (mKvsKeyMap[keyIndex] == hash)
	{
	uint32_t tempNvm3key = CONVERT_KEYMAP_INDEX_TO_NVM3KEY(keyIndex);
	VerifyOrDie(IsValidKvsNvm3Key(tempNvm3key) == true);

	size_t readCount;
	size_t length = strlen(key);
	if (strPrefix == nullptr)
	{
	// Use a calloc to initialize all bits to 0. alloc +1 for a null char
	strPrefix = static_cast<char *>(Platform::MemoryCalloc(1, length + 1));
	VerifyOrDie(strPrefix != nullptr);
	}

	// Collision prevention
	// Read the data from NVM3 it should be prefixed by the kvsString
	// else we will look for another matching hash in the map
	SilabsConfig::ReadConfigValueBin(tempNvm3key, reinterpret_cast<uint8_t *>(strPrefix), length, readCount, 0);
	if (strcmp(key, strPrefix) == 0)
	{
	// String matches we have confirmed the hash pointed us the right key data
	nvm3Key = tempNvm3key;
	Platform::MemoryFree(strPrefix);
	return CHIP_NO_ERROR;
	}
	}

	if (isSlotNeeded && (firstEmptyKeySlot == kMaxEntries) && (mKvsKeyMap[keyIndex] == 0))
	{
	firstEmptyKeySlot = keyIndex;
	}
	}

	Platform::MemoryFree(strPrefix);

	if (isSlotNeeded)
	{
	if (firstEmptyKeySlot != kMaxEntries)
	{
	nvm3Key = CONVERT_KEYMAP_INDEX_TO_NVM3KEY(firstEmptyKeySlot);
	VerifyOrDie(IsValidKvsNvm3Key(nvm3Key) == true);
	err = CHIP_NO_ERROR;
	}
	else
	{
	err = CHIP_ERROR_PERSISTED_STORAGE_FAILED;
	}
	}
	else
	{
	err = CHIP_ERROR_PERSISTED_STORAGE_VALUE_NOT_FOUND;
	}
	return err;
	}

	void KeyValueStoreManagerImpl::ForceKeyMapSave()
	{
	OnScheduledKeyMapSave(nullptr, nullptr);
	}

	void KeyValueStoreManagerImpl::OnScheduledKeyMapSave(System::Layer * systemLayer, void * appState)
	{
	SilabsConfig::WriteConfigValueBin(SilabsConfig::kConfigKey_KvsStringKeyMap, reinterpret_cast<const uint8_t *>(mKvsKeyMap),
	sizeof(mKvsKeyMap));
	}

	void KeyValueStoreManagerImpl::ScheduleKeyMapSave(void)
	{
	/*
	During commissioning, the key map will be modified multiples times subsequently.
	Commit the key map in nvm once it as stabilized.
	*/
	SystemLayer().StartTimer(
	std::chrono::duration_cast<System::Clock::Timeout>(System::Clock::Seconds32(SILABS_KVS_SAVE_DELAY_SECONDS)),
	KeyValueStoreManagerImpl::OnScheduledKeyMapSave, NULL);
	}

	CHIP_ERROR KeyValueStoreManagerImpl::_Get(const char * key, void * value, size_t value_size, size_t * read_bytes_size,
	size_t offset_bytes) const
	{
	VerifyOrReturnError(key != nullptr, CHIP_ERROR_INVALID_ARGUMENT);

	uint32_t nvm3Key;
	uint16_t hash = hashKvsKeyString(key);
	CHIP_ERROR err = MapKvsKeyToNvm3(key, hash, nvm3Key);
	VerifyOrReturnError(err == CHIP_NO_ERROR, err);

	size_t outLen;
	// The user doesn't need the KeyString prefix, Read data after it
	size_t KeyStringLen = strlen(key);
	err = SilabsConfig::ReadConfigValueBin(nvm3Key, reinterpret_cast<uint8_t *>(value), value_size, outLen,
	(offset_bytes + KeyStringLen));
	if (read_bytes_size)
	{
	*read_bytes_size = outLen;
	}

	if (err == CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND)
	{
	return CHIP_ERROR_PERSISTED_STORAGE_VALUE_NOT_FOUND;
	}

	return err;
	}

	CHIP_ERROR KeyValueStoreManagerImpl::_Put(const char * key, const void * value, size_t value_size)
	{
	VerifyOrReturnError(key != nullptr, CHIP_ERROR_INVALID_ARGUMENT);

	uint32_t nvm3Key;
	uint16_t hash = hashKvsKeyString(key);
	CHIP_ERROR err = MapKvsKeyToNvm3(key, hash, nvm3Key, /* isSlotNeeded */ true);
	VerifyOrReturnError(err == CHIP_NO_ERROR, err);

	// add the string Key as prefix to the stored data as a collision prevention mechanism.
	size_t keyStringLen = strlen(key);
	uint8_t * prefixedData = static_cast<uint8_t *>(Platform::MemoryAlloc(keyStringLen + value_size));
	VerifyOrDie(prefixedData != nullptr);
	memcpy(prefixedData, key, keyStringLen);
	memcpy(prefixedData + keyStringLen, value, value_size);

	err = SilabsConfig::WriteConfigValueBin(nvm3Key, prefixedData, keyStringLen + value_size);
	if (err == CHIP_NO_ERROR)
	{
	uint32_t keyIndex = CONVERT_NVM3KEY_TO_KEYMAP_INDEX(nvm3Key);
	mKvsKeyMap[keyIndex] = hash;
	ScheduleKeyMapSave();
	}
	Platform::MemoryFree(prefixedData);
	return err;
	}

	CHIP_ERROR KeyValueStoreManagerImpl::_Delete(const char * key)
	{
	VerifyOrReturnError(key != nullptr, CHIP_ERROR_INVALID_ARGUMENT);

	uint32_t nvm3Key;
	uint16_t hash = hashKvsKeyString(key);
	CHIP_ERROR err = MapKvsKeyToNvm3(key, hash, nvm3Key);
	VerifyOrReturnError(err == CHIP_NO_ERROR, err);

	err = SilabsConfig::ClearConfigValue(nvm3Key);
	if (err == CHIP_NO_ERROR)
	{
	uint32_t keyIndex = CONVERT_NVM3KEY_TO_KEYMAP_INDEX(nvm3Key);
	mKvsKeyMap[keyIndex] = 0;
	ScheduleKeyMapSave();
	}

	return err;
	}

	void KeyValueStoreManagerImpl::ErasePartition(void)
	{
	// Iterate over all the Matter Kvs nvm3 records and delete each one...
	for (uint32_t nvm3Key = SilabsConfig::kMinConfigKey_MatterKvs; nvm3Key <= SilabsConfig::kMaxConfigKey_MatterKvs; nvm3Key++)
	{
	SilabsConfig::ClearConfigValue(nvm3Key);
	}

	memset(mKvsKeyMap, 0, sizeof(mKvsKeyMap));
	}

	void KeyValueStoreManagerImpl::KvsMapMigration(void)
	{
	size_t readlen = 0;
	constexpr uint8_t oldMaxEntires = 120;
	char mKvsStoredKeyString[oldMaxEntires][PersistentStorageDelegate::kKeyLengthMax + 1] = { 0 };
	CHIP_ERROR err =
	SilabsConfig::ReadConfigValueBin(SilabsConfig::kConfigKey_KvsStringKeyMap, reinterpret_cast<uint8_t *>(mKvsStoredKeyString),
	sizeof(mKvsStoredKeyString), readlen);

	if (err == CHIP_NO_ERROR)
	{
	for (uint8_t i = 0; i < oldMaxEntires; i++)
	{
	if (mKvsStoredKeyString[i][0] != 0)
	{
	size_t dataLen = 0;
	uint32_t nvm3Key = CONVERT_KEYMAP_INDEX_TO_NVM3KEY(i);

	if (SilabsConfig::ConfigValueExists(nvm3Key, dataLen))
	{
	// Read old data and prefix it with the string Key for the collision prevention mechanism.
	size_t keyStringLen = strlen(mKvsStoredKeyString[i]);
	uint8_t * prefixedData = static_cast<uint8_t *>(Platform::MemoryAlloc(keyStringLen + dataLen));
	VerifyOrDie(prefixedData != nullptr);
	memcpy(prefixedData, mKvsStoredKeyString[i], keyStringLen);

	SilabsConfig::ReadConfigValueBin(nvm3Key, prefixedData + keyStringLen, dataLen, readlen);
	SilabsConfig::WriteConfigValueBin(nvm3Key, prefixedData, keyStringLen + dataLen);
	mKvsKeyMap[i] = KeyValueStoreMgrImpl().hashKvsKeyString(mKvsStoredKeyString[i]);
	Platform::MemoryFree(prefixedData);
	}
	}
	}
	ForceKeyMapSave();
	}
	else if (err != CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND)
	{
	// Error reading the old String Keymap. Cannot not resolve stored data for migration.
	ChipLogError(DeviceLayer, "Migration failed ! Kvs Key map could not be recovered %" CHIP_ERROR_FORMAT, err.Format());
	// start with a fresh kvs section.
	KeyValueStoreMgrImpl().ErasePartition();
	}
	}

	} // namespace PersistedStorage
	} // namespace DeviceLayer
	} // namespace chip