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 <lib/support/BufferReader.h>
22 : #include <lib/support/BufferWriter.h>
23 : #include <lib/support/Span.h>
24 :
25 : #include <cstring>
26 : #include <inttypes.h>
27 :
28 : namespace chip {
29 : namespace app {
30 :
31 : /**
32 : * Interface for persisting attribute values. This will always write attributes in storage as little-endian
33 : * and uses a different key space from AttributePersistenceProvider.
34 : */
35 :
36 : class SafeAttributePersistenceProvider
37 : {
38 : public:
39 1 : virtual ~SafeAttributePersistenceProvider() = default;
40 1 : SafeAttributePersistenceProvider() = default;
41 :
42 : // The following API provides helper functions to simplify the access of commonly used types.
43 : // The API may not be complete.
44 : // Currently implemented write and read types are: bool, uint8_t, uint16_t, uint32_t, unit64_t and
45 : // their nullable varieties, as well as ByteSpans.
46 :
47 : /**
48 : * Write an attribute value of type intX, uintX or bool to non-volatile memory.
49 : *
50 : * @param [in] aPath the attribute path for the data being written.
51 : * @param [in] aValue the data to write.
52 : */
53 : template <typename T, std::enable_if_t<std::is_integral<T>::value, bool> = true>
54 : CHIP_ERROR WriteScalarValue(const ConcreteAttributePath & aPath, T aValue)
55 : {
56 : uint8_t value[sizeof(T)];
57 : auto w = Encoding::LittleEndian::BufferWriter(value, sizeof(T));
58 : if constexpr (std::is_signed_v<T>)
59 : {
60 : w.EndianPutSigned(aValue, sizeof(T));
61 : }
62 : else
63 : {
64 : w.EndianPut(aValue, sizeof(T));
65 : }
66 :
67 : return SafeWriteValue(aPath, ByteSpan(value));
68 : }
69 :
70 : /**
71 : * Read an attribute of type intX, uintX or bool from non-volatile memory.
72 : *
73 : * @param [in] aPath the attribute path for the data being persisted.
74 : * @param [in,out] aValue where to place the data.
75 : *
76 : * @retval CHIP_ERROR_PERSISTED_STORAGE_VALUE_NOT_FOUND if no stored value exists for the attribute
77 : */
78 : template <typename T, std::enable_if_t<std::is_integral<T>::value, bool> = true>
79 : CHIP_ERROR ReadScalarValue(const ConcreteAttributePath & aPath, T & aValue)
80 : {
81 : uint8_t attrData[sizeof(T)];
82 : MutableByteSpan tempVal(attrData);
83 : ReturnErrorOnFailure(SafeReadValue(aPath, tempVal));
84 : VerifyOrReturnError(tempVal.size() == sizeof(T), CHIP_ERROR_INCORRECT_STATE);
85 : Encoding::LittleEndian::Reader r(tempVal.data(), tempVal.size());
86 : r.RawReadLowLevelBeCareful(&aValue);
87 : return r.StatusCode();
88 : }
89 :
90 : /**
91 : * Write an attribute value of type nullable intX, uintX to non-volatile memory.
92 : *
93 : * @param [in] aPath the attribute path for the data being written.
94 : * @param [in] aValue the data to write.
95 : */
96 : template <typename T, std::enable_if_t<std::is_integral<T>::value, bool> = true>
97 : CHIP_ERROR WriteScalarValue(const ConcreteAttributePath & aPath, const DataModel::Nullable<T> & aValue)
98 : {
99 : typename NumericAttributeTraits<T>::StorageType storageValue;
100 : if (aValue.IsNull())
101 : {
102 : NumericAttributeTraits<T>::SetNull(storageValue);
103 : }
104 : else
105 : {
106 : NumericAttributeTraits<T>::WorkingToStorage(aValue.Value(), storageValue);
107 : }
108 : return WriteScalarValue(aPath, storageValue);
109 : }
110 :
111 : /**
112 : * Read an attribute of type nullable intX, uintX from non-volatile memory.
113 : *
114 : * @param [in] aPath the attribute path for the data being persisted.
115 : * @param [in,out] aValue where to place the data.
116 : *
117 : * @retval CHIP_ERROR_PERSISTED_STORAGE_VALUE_NOT_FOUND if no stored value exists for the attribute
118 : */
119 : template <typename T, std::enable_if_t<std::is_integral<T>::value, bool> = true>
120 : CHIP_ERROR ReadScalarValue(const ConcreteAttributePath & aPath, DataModel::Nullable<T> & aValue)
121 : {
122 : typename NumericAttributeTraits<T>::StorageType storageValue;
123 : ReturnErrorOnFailure(ReadScalarValue(aPath, storageValue));
124 :
125 : if (NumericAttributeTraits<T>::IsNullValue(storageValue))
126 : {
127 : aValue.SetNull();
128 : return CHIP_NO_ERROR;
129 : }
130 :
131 : // Consider checking CanRepresentValue here, so we don't produce invalid data
132 : // if the storage hands us invalid values.
133 : aValue.SetNonNull(NumericAttributeTraits<T>::StorageToWorking(storageValue));
134 : return CHIP_NO_ERROR;
135 : }
136 :
137 : /**
138 : * Write an attribute value from the attribute store (i.e. not a struct or
139 : * list) to non-volatile memory.
140 : *
141 : * @param [in] aPath the attribute path for the data being written.
142 : * @param [in] aValue the data to write. The value will be stored as-is.
143 : */
144 : virtual CHIP_ERROR SafeWriteValue(const ConcreteAttributePath & aPath, const ByteSpan & aValue) = 0;
145 :
146 : /**
147 : * Read an attribute value as a raw sequence of bytes from non-volatile memory.
148 : *
149 : * @param [in] aPath the attribute path for the data being persisted.
150 : * @param [in,out] aValue where to place the data. The size of the buffer
151 : * will be equal to `aValue.size()`. On success aValue.size()
152 : * will be the actual number of bytes read.
153 : *
154 : * @retval CHIP_ERROR_PERSISTED_STORAGE_VALUE_NOT_FOUND if no stored value exists for the attribute
155 : * @retval CHIP_ERROR_BUFFER_TOO_SMALL aValue.size() is too small to hold the value.
156 : */
157 : virtual CHIP_ERROR SafeReadValue(const ConcreteAttributePath & aPath, MutableByteSpan & aValue) = 0;
158 : };
159 :
160 : /**
161 : * Instance getter for the global SafeAttributePersistenceProvider.
162 : *
163 : * Callers have to externally synchronize usage of this function.
164 : *
165 : * @return The global SafeAttributePersistenceProvider. This must never be null.
166 : */
167 : SafeAttributePersistenceProvider * GetSafeAttributePersistenceProvider();
168 :
169 : /**
170 : * Instance setter for the global SafeAttributePersistenceProvider.
171 : *
172 : * Callers have to externally synchronize usage of this function.
173 : *
174 : * If the `provider` is nullptr, the value is not changed.
175 : *
176 : * @param[in] aProvider the SafeAttributePersistenceProvider implementation to use.
177 : */
178 : void SetSafeAttributePersistenceProvider(SafeAttributePersistenceProvider * aProvider);
179 :
180 : } // namespace app
181 : } // namespace chip
|
