8683fca395
this change introduces a new class LightFlattenable<> which is a protocol to flatten simple objects that don't require binders or file descriptors; the benefit of this protocol is that it doesn't require the objects to have a virtual table and give us a consitant way of doing this. we also introduce an implementation of this protocol for POD structures, LightFlattenablePod<>. Parcel has been update to handle this protocol automatically. Sensor, Rect, Point and Region now use this new protocol. Change-Id: Icb3ce7fa1d785249eb666f39c2129f2fc143ea4a
135 lines
4.0 KiB
C++
135 lines
4.0 KiB
C++
/*
|
|
* Copyright (C) 2010 The Android Open Source Project
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#ifndef ANDROID_UTILS_FLATTENABLE_H
|
|
#define ANDROID_UTILS_FLATTENABLE_H
|
|
|
|
|
|
#include <stdint.h>
|
|
#include <sys/types.h>
|
|
#include <utils/Errors.h>
|
|
|
|
namespace android {
|
|
|
|
/*
|
|
* The Flattenable interface allows an object to serialize itself out
|
|
* to a byte-buffer and an array of file descriptors.
|
|
*/
|
|
|
|
class Flattenable
|
|
{
|
|
public:
|
|
// size in bytes of the flattened object
|
|
virtual size_t getFlattenedSize() const = 0;
|
|
|
|
// number of file descriptors to flatten
|
|
virtual size_t getFdCount() const = 0;
|
|
|
|
// flattens the object into buffer.
|
|
// size should be at least of getFlattenedSize()
|
|
// file descriptors are written in the fds[] array but ownership is
|
|
// not transfered (ie: they must be dupped by the caller of
|
|
// flatten() if needed).
|
|
virtual status_t flatten(void* buffer, size_t size,
|
|
int fds[], size_t count) const = 0;
|
|
|
|
// unflattens the object from buffer.
|
|
// size should be equal to the value of getFlattenedSize() when the
|
|
// object was flattened.
|
|
// unflattened file descriptors are found in the fds[] array and
|
|
// don't need to be dupped(). ie: the caller of unflatten doesn't
|
|
// keep ownership. If a fd is not retained by unflatten() it must be
|
|
// explicitly closed.
|
|
virtual status_t unflatten(void const* buffer, size_t size,
|
|
int fds[], size_t count) = 0;
|
|
|
|
protected:
|
|
virtual ~Flattenable() = 0;
|
|
|
|
};
|
|
|
|
/*
|
|
* LightFlattenable is a protocol allowing object to serialize themselves out
|
|
* to a byte-buffer.
|
|
*
|
|
* LightFlattenable objects must implement this protocol.
|
|
*
|
|
* LightFlattenable doesn't require the object to be virtual.
|
|
*/
|
|
template <typename T>
|
|
class LightFlattenable {
|
|
public:
|
|
// returns whether this object always flatten into the same size.
|
|
// for efficiency, this should always be inline.
|
|
inline bool isFixedSize() const;
|
|
|
|
// returns size in bytes of the flattened object. must be a constant.
|
|
inline size_t getSize() const;
|
|
|
|
// flattens the object into buffer.
|
|
inline status_t flatten(void* buffer) const;
|
|
|
|
// unflattens the object from buffer of given size.
|
|
inline status_t unflatten(void const* buffer, size_t size);
|
|
};
|
|
|
|
template <typename T>
|
|
inline bool LightFlattenable<T>::isFixedSize() const {
|
|
return static_cast<T const*>(this)->T::isFixedSize();
|
|
}
|
|
template <typename T>
|
|
inline size_t LightFlattenable<T>::getSize() const {
|
|
return static_cast<T const*>(this)->T::getSize();
|
|
}
|
|
template <typename T>
|
|
inline status_t LightFlattenable<T>::flatten(void* buffer) const {
|
|
return static_cast<T const*>(this)->T::flatten(buffer);
|
|
}
|
|
template <typename T>
|
|
inline status_t LightFlattenable<T>::unflatten(void const* buffer, size_t size) {
|
|
return static_cast<T*>(this)->T::unflatten(buffer, size);
|
|
}
|
|
|
|
/*
|
|
* LightFlattenablePod is an implementation of the LightFlattenable protocol
|
|
* for POD (plain-old-data) objects.
|
|
*/
|
|
template <typename T>
|
|
class LightFlattenablePod : public LightFlattenable<T> {
|
|
public:
|
|
inline bool isFixedSize() const {
|
|
return true;
|
|
}
|
|
|
|
inline size_t getSize() const {
|
|
return sizeof(T);
|
|
}
|
|
inline status_t flatten(void* buffer) const {
|
|
*reinterpret_cast<T*>(buffer) = *static_cast<T const*>(this);
|
|
return NO_ERROR;
|
|
}
|
|
inline status_t unflatten(void const* buffer, size_t) {
|
|
*static_cast<T*>(this) = *reinterpret_cast<T const*>(buffer);
|
|
return NO_ERROR;
|
|
}
|
|
};
|
|
|
|
|
|
}; // namespace android
|
|
|
|
|
|
#endif /* ANDROID_UTILS_FLATTENABLE_H */
|