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/*
* Copyright 2017 The Native Object Protocols 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 LIBNOP_INCLUDE_NOP_UTILITY_BOUNDED_READER_H_
#define LIBNOP_INCLUDE_NOP_UTILITY_BOUNDED_READER_H_
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <nop/base/encoding.h>
#include <nop/base/handle.h>
#include <nop/base/utility.h>
namespace nop {
// BoundedReader is a reader type that wraps another reader pointer and tracks
// the number of bytes read. Reader operations are transparently passed to the
// underlying reader unless the requested operation would exceed the size limit
// set at construction. BufferReader can also skip padding remaining in the
// input up to the size limit in situations that require specific input payload
// size.
template <typename Reader>
class BoundedReader {
public:
constexpr BoundedReader() = default;
constexpr BoundedReader(const BoundedReader&) = default;
constexpr BoundedReader(Reader* reader, std::size_t size)
: reader_{reader}, size_{size} {}
constexpr BoundedReader& operator=(const BoundedReader&) = default;
constexpr Status<void> Ensure(std::size_t size) {
if (size_ - index_ < size)
return ErrorStatus::ReadLimitReached;
else
return reader_->Ensure(size);
}
constexpr Status<void> Read(std::uint8_t* byte) {
if (index_ < size_) {
auto status = reader_->Read(byte);
if (!status)
return status;
index_ += 1;
return {};
} else {
return ErrorStatus::ReadLimitReached;
}
}
template <typename T, typename Enable = EnableIfArithmetic<T>>
constexpr Status<void> Read(T* begin, T* end) {
const std::size_t element_size = sizeof(T);
const std::size_t length = end - begin;
const std::size_t length_bytes = length * element_size;
if (length_bytes > (size_ - index_))
return ErrorStatus::ReadLimitReached;
auto status = reader_->Read(begin, end);
if (!status)
return status;
index_ += length_bytes;
return {};
}
constexpr Status<void> Skip(std::size_t padding_bytes) {
if (padding_bytes > (size_ - index_))
return ErrorStatus::ReadLimitReached;
auto status = reader_->Skip(padding_bytes);
if (!status)
return status;
index_ += padding_bytes;
return {};
}
// Skips any bytes remaining in the limit set at construction.
constexpr Status<void> ReadPadding() {
const std::size_t padding_bytes = size_ - index_;
auto status = reader_->Skip(padding_bytes);
if (!status)
return status;
index_ += padding_bytes;
return {};
}
template <typename HandleType>
constexpr Status<HandleType> GetHandle(HandleReference handle_reference) {
return reader_->GetHandle(handle_reference);
}
constexpr bool empty() const { return index_ == size_; }
constexpr std::size_t size() const { return index_; }
constexpr std::size_t capacity() const { return size_; }
private:
Reader* reader_{nullptr};
std::size_t size_{0};
std::size_t index_{0};
};
} // namespace nop
#endif // LIBNOP_INCLUDE_NOP_UTILITY_BOUNDED_READER_H_
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