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// Copyright 2021 The Dawn Authors
//
// 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 DAWNWIRE_BUFFERCONSUMER_H_
#define DAWNWIRE_BUFFERCONSUMER_H_
#include "dawn_wire/WireResult.h"
#include <cstddef>
namespace dawn::wire {
// BufferConsumer is a utility class that allows reading bytes from a buffer
// while simultaneously decrementing the amount of remaining space by exactly
// the amount read. It helps prevent bugs where incrementing a pointer and
// decrementing a size value are not kept in sync.
// BufferConsumer also contains bounds checks to prevent reading out-of-bounds.
template <typename BufferT>
class BufferConsumer {
static_assert(sizeof(BufferT) == 1,
"BufferT must be 1-byte, but may have const/volatile qualifiers.");
public:
BufferConsumer(BufferT* buffer, size_t size) : mBuffer(buffer), mSize(size) {
}
BufferT* Buffer() const {
return mBuffer;
}
size_t AvailableSize() const {
return mSize;
}
protected:
template <typename T, typename N>
WireResult NextN(N count, T** data);
template <typename T>
WireResult Next(T** data);
template <typename T>
WireResult Peek(T** data);
private:
BufferT* mBuffer;
size_t mSize;
};
class SerializeBuffer : public BufferConsumer<char> {
public:
using BufferConsumer::BufferConsumer;
using BufferConsumer::Next;
using BufferConsumer::NextN;
};
class DeserializeBuffer : public BufferConsumer<const volatile char> {
public:
using BufferConsumer::BufferConsumer;
using BufferConsumer::Peek;
template <typename T, typename N>
WireResult ReadN(N count, const volatile T** data) {
return NextN(count, data);
}
template <typename T>
WireResult Read(const volatile T** data) {
return Next(data);
}
};
} // namespace dawn::wire
#endif // DAWNWIRE_BUFFERCONSUMER_H_