Mathias Agopian | a580e68 | 2010-02-11 17:30:52 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2010 The Android Open Source Project |
| 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 | |
| 17 | #ifndef ANDROID_UTILS_FLATTENABLE_H |
| 18 | #define ANDROID_UTILS_FLATTENABLE_H |
| 19 | |
| 20 | |
| 21 | #include <stdint.h> |
| 22 | #include <sys/types.h> |
| 23 | #include <utils/Errors.h> |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 24 | #include <utils/Debug.h> |
Mathias Agopian | a580e68 | 2010-02-11 17:30:52 -0800 | [diff] [blame] | 25 | |
| 26 | namespace android { |
| 27 | |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 28 | |
| 29 | class FlattenableUtils { |
| 30 | public: |
| 31 | template<int N> |
| 32 | static size_t align(size_t size) { |
| 33 | COMPILE_TIME_ASSERT_FUNCTION_SCOPE( !(N & (N-1)) ); |
| 34 | return (size + (N-1)) & ~(N-1); |
| 35 | } |
| 36 | |
| 37 | template<int N> |
Mathias Agopian | ddff623 | 2013-08-01 12:47:58 -0700 | [diff] [blame] | 38 | static size_t align(void const*& buffer) { |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 39 | COMPILE_TIME_ASSERT_FUNCTION_SCOPE( !(N & (N-1)) ); |
| 40 | intptr_t b = intptr_t(buffer); |
| 41 | buffer = (void*)((intptr_t(buffer) + (N-1)) & ~(N-1)); |
| 42 | return size_t(intptr_t(buffer) - b); |
| 43 | } |
| 44 | |
Mathias Agopian | ddff623 | 2013-08-01 12:47:58 -0700 | [diff] [blame] | 45 | template<int N> |
| 46 | static size_t align(void*& buffer) { |
| 47 | return align<N>( const_cast<void const*&>(buffer) ); |
| 48 | } |
| 49 | |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 50 | static void advance(void*& buffer, size_t& size, size_t offset) { |
| 51 | buffer = reinterpret_cast<void*>( intptr_t(buffer) + offset ); |
| 52 | size -= offset; |
| 53 | } |
| 54 | |
| 55 | static void advance(void const*& buffer, size_t& size, size_t offset) { |
| 56 | buffer = reinterpret_cast<void const*>( intptr_t(buffer) + offset ); |
| 57 | size -= offset; |
| 58 | } |
| 59 | |
| 60 | // write a POD structure |
| 61 | template<typename T> |
| 62 | static void write(void*& buffer, size_t& size, const T& value) { |
| 63 | *static_cast<T*>(buffer) = value; |
| 64 | advance(buffer, size, sizeof(T)); |
| 65 | } |
| 66 | |
| 67 | // read a POD structure |
| 68 | template<typename T> |
| 69 | static void read(void const*& buffer, size_t& size, T& value) { |
| 70 | value = *static_cast<T const*>(buffer); |
| 71 | advance(buffer, size, sizeof(T)); |
| 72 | } |
| 73 | }; |
| 74 | |
| 75 | |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 76 | /* |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 77 | * The Flattenable protocol allows an object to serialize itself out |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 78 | * to a byte-buffer and an array of file descriptors. |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 79 | * Flattenable objects must implement this protocol. |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 80 | */ |
| 81 | |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 82 | template <typename T> |
| 83 | class Flattenable { |
Mathias Agopian | a580e68 | 2010-02-11 17:30:52 -0800 | [diff] [blame] | 84 | public: |
| 85 | // size in bytes of the flattened object |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 86 | inline size_t getFlattenedSize() const; |
Mathias Agopian | a580e68 | 2010-02-11 17:30:52 -0800 | [diff] [blame] | 87 | |
| 88 | // number of file descriptors to flatten |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 89 | inline size_t getFdCount() const; |
Mathias Agopian | a580e68 | 2010-02-11 17:30:52 -0800 | [diff] [blame] | 90 | |
| 91 | // flattens the object into buffer. |
| 92 | // size should be at least of getFlattenedSize() |
| 93 | // file descriptors are written in the fds[] array but ownership is |
| 94 | // not transfered (ie: they must be dupped by the caller of |
| 95 | // flatten() if needed). |
Mathias Agopian | ddff623 | 2013-08-01 12:47:58 -0700 | [diff] [blame] | 96 | inline status_t flatten(void*& buffer, size_t& size, int*& fds, size_t& count) const; |
Mathias Agopian | a580e68 | 2010-02-11 17:30:52 -0800 | [diff] [blame] | 97 | |
| 98 | // unflattens the object from buffer. |
| 99 | // size should be equal to the value of getFlattenedSize() when the |
| 100 | // object was flattened. |
| 101 | // unflattened file descriptors are found in the fds[] array and |
| 102 | // don't need to be dupped(). ie: the caller of unflatten doesn't |
| 103 | // keep ownership. If a fd is not retained by unflatten() it must be |
| 104 | // explicitly closed. |
Mathias Agopian | ddff623 | 2013-08-01 12:47:58 -0700 | [diff] [blame] | 105 | inline status_t unflatten(void const*& buffer, size_t& size, int const*& fds, size_t& count); |
Mathias Agopian | a580e68 | 2010-02-11 17:30:52 -0800 | [diff] [blame] | 106 | }; |
| 107 | |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 108 | template<typename T> |
| 109 | inline size_t Flattenable<T>::getFlattenedSize() const { |
| 110 | return static_cast<T const*>(this)->T::getFlattenedSize(); |
| 111 | } |
| 112 | template<typename T> |
| 113 | inline size_t Flattenable<T>::getFdCount() const { |
| 114 | return static_cast<T const*>(this)->T::getFdCount(); |
| 115 | } |
| 116 | template<typename T> |
| 117 | inline status_t Flattenable<T>::flatten( |
| 118 | void*& buffer, size_t& size, int*& fds, size_t& count) const { |
| 119 | return static_cast<T const*>(this)->T::flatten(buffer, size, fds, count); |
| 120 | } |
| 121 | template<typename T> |
| 122 | inline status_t Flattenable<T>::unflatten( |
| 123 | void const*& buffer, size_t& size, int const*& fds, size_t& count) { |
| 124 | return static_cast<T*>(this)->T::unflatten(buffer, size, fds, count); |
| 125 | } |
| 126 | |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 127 | /* |
| 128 | * LightFlattenable is a protocol allowing object to serialize themselves out |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 129 | * to a byte-buffer. Because it doesn't handle file-descriptors, |
| 130 | * LightFlattenable is usually more size efficient than Flattenable. |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 131 | * LightFlattenable objects must implement this protocol. |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 132 | */ |
| 133 | template <typename T> |
| 134 | class LightFlattenable { |
| 135 | public: |
| 136 | // returns whether this object always flatten into the same size. |
| 137 | // for efficiency, this should always be inline. |
| 138 | inline bool isFixedSize() const; |
| 139 | |
| 140 | // returns size in bytes of the flattened object. must be a constant. |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 141 | inline size_t getFlattenedSize() const; |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 142 | |
| 143 | // flattens the object into buffer. |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 144 | inline status_t flatten(void* buffer, size_t size) const; |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 145 | |
| 146 | // unflattens the object from buffer of given size. |
| 147 | inline status_t unflatten(void const* buffer, size_t size); |
| 148 | }; |
| 149 | |
| 150 | template <typename T> |
| 151 | inline bool LightFlattenable<T>::isFixedSize() const { |
| 152 | return static_cast<T const*>(this)->T::isFixedSize(); |
| 153 | } |
| 154 | template <typename T> |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 155 | inline size_t LightFlattenable<T>::getFlattenedSize() const { |
| 156 | return static_cast<T const*>(this)->T::getFlattenedSize(); |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 157 | } |
| 158 | template <typename T> |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 159 | inline status_t LightFlattenable<T>::flatten(void* buffer, size_t size) const { |
| 160 | return static_cast<T const*>(this)->T::flatten(buffer, size); |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 161 | } |
| 162 | template <typename T> |
| 163 | inline status_t LightFlattenable<T>::unflatten(void const* buffer, size_t size) { |
| 164 | return static_cast<T*>(this)->T::unflatten(buffer, size); |
| 165 | } |
| 166 | |
| 167 | /* |
| 168 | * LightFlattenablePod is an implementation of the LightFlattenable protocol |
| 169 | * for POD (plain-old-data) objects. |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 170 | * Simply derive from LightFlattenablePod<Foo> to make Foo flattenable; no |
| 171 | * need to implement any methods; obviously Foo must be a POD structure. |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 172 | */ |
| 173 | template <typename T> |
| 174 | class LightFlattenablePod : public LightFlattenable<T> { |
| 175 | public: |
| 176 | inline bool isFixedSize() const { |
| 177 | return true; |
| 178 | } |
| 179 | |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 180 | inline size_t getFlattenedSize() const { |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 181 | return sizeof(T); |
| 182 | } |
Mathias Agopian | 6d611a8 | 2013-07-29 21:24:40 -0700 | [diff] [blame] | 183 | inline status_t flatten(void* buffer, size_t size) const { |
| 184 | if (size < sizeof(T)) return NO_MEMORY; |
Mathias Agopian | 2497a15 | 2012-08-12 19:37:16 -0700 | [diff] [blame] | 185 | *reinterpret_cast<T*>(buffer) = *static_cast<T const*>(this); |
| 186 | return NO_ERROR; |
| 187 | } |
| 188 | inline status_t unflatten(void const* buffer, size_t) { |
| 189 | *static_cast<T*>(this) = *reinterpret_cast<T const*>(buffer); |
| 190 | return NO_ERROR; |
| 191 | } |
| 192 | }; |
| 193 | |
| 194 | |
Mathias Agopian | a580e68 | 2010-02-11 17:30:52 -0800 | [diff] [blame] | 195 | }; // namespace android |
| 196 | |
| 197 | |
| 198 | #endif /* ANDROID_UTILS_FLATTENABLE_H */ |