Line data    Source code

       1             : /*
       2             :  *    Copyright (c) 2021 Project CHIP Authors
       3             :  *
       4             :  *    Licensed under the Apache License, Version 2.0 (the "License");
       5             :  *    you may not use this file except in compliance with the License.
       6             :  *    You may obtain a copy of the License at
       7             :  *
       8             :  *        http://www.apache.org/licenses/LICENSE-2.0
       9             :  *
      10             :  *    Unless required by applicable law or agreed to in writing, software
      11             :  *    distributed under the License is distributed on an "AS IS" BASIS,
      12             :  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      13             :  *    See the License for the specific language governing permissions and
      14             :  *    limitations under the License.
      15             :  */
      16             : #pragma once
      17             : 
      18             : #include <app/ConcreteAttributePath.h>
      19             : #include <app/data-model/Nullable.h>
      20             : #include <app/util/attribute-metadata.h>
      21             : #include <cstring>
      22             : #include <inttypes.h>
      23             : #include <lib/support/BufferReader.h>
      24             : #include <lib/support/BufferWriter.h>
      25             : #include <lib/support/Span.h>
      26             : 
      27             : namespace chip {
      28             : namespace app {
      29             : 
      30             : /**
      31             :  * Interface for persisting attribute values. This will always write attributes in storage as little-endian
      32             :  * and uses a different key space from AttributePersistenceProvider.
      33             :  */
      34             : 
      35             : class SafeAttributePersistenceProvider
      36             : {
      37             : public:
      38           1 :     virtual ~SafeAttributePersistenceProvider() = default;
      39           1 :     SafeAttributePersistenceProvider()          = default;
      40             : 
      41             :     // The following API provides helper functions to simplify the access of commonly used types.
      42             :     // The API may not be complete.
      43             :     // Currently implemented write and read types are: uint8_t, uint16_t, uint32_t, unit64_t and
      44             :     // their nullable varieties, and bool.
      45             : 
      46             :     /**
      47             :      * Write an attribute value of type intX, uintX or bool to non-volatile memory.
      48             :      *
      49             :      * @param [in] aPath the attribute path for the data being written.
      50             :      * @param [in] aValue the data to write.
      51             :      */
      52             :     template <typename T, std::enable_if_t<std::is_integral<T>::value, bool> = true>
      53             :     CHIP_ERROR WriteScalarValue(const ConcreteAttributePath & aPath, T & aValue)
      54             :     {
      55             :         uint8_t value[sizeof(T)];
      56             :         auto w = Encoding::LittleEndian::BufferWriter(value, sizeof(T));
      57             :         if constexpr (std::is_signed_v<T>)
      58             :         {
      59             :             w.EndianPutSigned(aValue, sizeof(T));
      60             :         }
      61             :         else
      62             :         {
      63             :             w.EndianPut(aValue, sizeof(T));
      64             :         }
      65             : 
      66             :         return SafeWriteValue(aPath, ByteSpan(value));
      67             :     }
      68             : 
      69             :     /**
      70             :      * Read an attribute of type intX, uintX or bool from non-volatile memory.
      71             :      *
      72             :      * @param [in]     aPath the attribute path for the data being persisted.
      73             :      * @param [in,out] aValue where to place the data.
      74             :      */
      75             :     template <typename T, std::enable_if_t<std::is_integral<T>::value, bool> = true>
      76             :     CHIP_ERROR ReadScalarValue(const ConcreteAttributePath & aPath, T & aValue)
      77             :     {
      78             :         uint8_t attrData[sizeof(T)];
      79             :         MutableByteSpan tempVal(attrData);
      80             :         auto err = SafeReadValue(aPath, tempVal);
      81             :         if (err != CHIP_NO_ERROR)
      82             :         {
      83             :             return err;
      84             :         }
      85             : 
      86             :         Encoding::LittleEndian::Reader r(tempVal.data(), tempVal.size());
      87             :         r.RawReadLowLevelBeCareful(&aValue);
      88             :         return r.StatusCode();
      89             :     }
      90             : 
      91             :     /**
      92             :      * Write an attribute value of type nullable intX, uintX to non-volatile memory.
      93             :      *
      94             :      * @param [in] aPath the attribute path for the data being written.
      95             :      * @param [in] aValue the data to write.
      96             :      */
      97             :     template <typename T, std::enable_if_t<std::is_integral<T>::value, bool> = true>
      98             :     CHIP_ERROR WriteScalarValue(const ConcreteAttributePath & aPath, DataModel::Nullable<T> & aValue)
      99             :     {
     100             :         typename NumericAttributeTraits<T>::StorageType storageValue;
     101             :         if (aValue.IsNull())
     102             :         {
     103             :             NumericAttributeTraits<T>::SetNull(storageValue);
     104             :         }
     105             :         else
     106             :         {
     107             :             NumericAttributeTraits<T>::WorkingToStorage(aValue.Value(), storageValue);
     108             :         }
     109             :         return WriteScalarValue(aPath, storageValue);
     110             :     }
     111             : 
     112             :     /**
     113             :      * Read an attribute of type nullable intX, uintX from non-volatile memory.
     114             :      *
     115             :      * @param [in]     aPath the attribute path for the data being persisted.
     116             :      * @param [in,out] aValue where to place the data.
     117             :      */
     118             :     template <typename T, std::enable_if_t<std::is_integral<T>::value, bool> = true>
     119             :     CHIP_ERROR ReadScalarValue(const ConcreteAttributePath & aPath, DataModel::Nullable<T> & aValue)
     120             :     {
     121             :         typename NumericAttributeTraits<T>::StorageType storageValue;
     122             :         CHIP_ERROR err = ReadScalarValue(aPath, storageValue);
     123             :         if (err != CHIP_NO_ERROR)
     124             :         {
     125             :             return err;
     126             :         }
     127             : 
     128             :         if (NumericAttributeTraits<T>::IsNullValue(storageValue))
     129             :         {
     130             :             aValue.SetNull();
     131             :             return CHIP_NO_ERROR;
     132             :         }
     133             : 
     134             :         // Consider checking CanRepresentValue here, so we don't produce invalid data
     135             :         // if the storage hands us invalid values.
     136             :         aValue.SetNonNull(NumericAttributeTraits<T>::StorageToWorking(storageValue));
     137             :         return CHIP_NO_ERROR;
     138             :     }
     139             : 
     140             : protected:
     141             :     /**
     142             :      * Write an attribute value from the attribute store (i.e. not a struct or
     143             :      * list) to non-volatile memory.
     144             :      *
     145             :      * @param [in] aPath the attribute path for the data being written.
     146             :      * @param [in] aValue the data to write. The value should be stored as-is.
     147             :      */
     148             :     virtual CHIP_ERROR SafeWriteValue(const ConcreteAttributePath & aPath, const ByteSpan & aValue) = 0;
     149             : 
     150             :     /**
     151             :      * Read an attribute value from non-volatile memory.
     152             :      * It can be assumed that this method will never be called upon to read
     153             :      * an attribute of type string or long-string.
     154             :      *
     155             :      * @param [in]     aPath the attribute path for the data being persisted.
     156             :      * @param [in,out] aValue where to place the data.  The size of the buffer
     157             :      *                 will be equal to `aValue.size()`.  The callee is expected to adjust
     158             :      *                 aValue's size to the actual number of bytes read.
     159             :      */
     160             :     virtual CHIP_ERROR SafeReadValue(const ConcreteAttributePath & aPath, MutableByteSpan & aValue) = 0;
     161             : };
     162             : 
     163             : /**
     164             :  * Instance getter for the global SafeAttributePersistenceProvider.
     165             :  *
     166             :  * Callers have to externally synchronize usage of this function.
     167             :  *
     168             :  * @return The global SafeAttributePersistenceProvider.  This must never be null.
     169             :  */
     170             : SafeAttributePersistenceProvider * GetSafeAttributePersistenceProvider();
     171             : 
     172             : /**
     173             :  * Instance setter for the global SafeAttributePersistenceProvider.
     174             :  *
     175             :  * Callers have to externally synchronize usage of this function.
     176             :  *
     177             :  * If the `provider` is nullptr, the value is not changed.
     178             :  *
     179             :  * @param[in] aProvider the SafeAttributePersistenceProvider implementation to use.
     180             :  */
     181             : void SetSafeAttributePersistenceProvider(SafeAttributePersistenceProvider * aProvider);
     182             : 
     183             : } // namespace app
     184             : } // namespace chip