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// Copyright 2019 Google Inc.
//
// 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 TINK_STREAMINGAEAD_BUFFERED_INPUT_STREAM_H_
#define TINK_STREAMINGAEAD_BUFFERED_INPUT_STREAM_H_
#include <memory>
#include <vector>
#include "tink/input_stream.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"
namespace crypto {
namespace tink {
namespace streamingaead {
// An InputStream that initially buffers all the read bytes, and offers
// rewind-functionality, until explicitly instructed to disable
// rewinding (and stop buffering).
class BufferedInputStream : public crypto::tink::InputStream {
public:
// Constructs an InputStream that will read from 'input_stream',
// buffering all the read bytes in memory, and offering rewinding
// to the beginning of the stream (as long as rewinding is enabled).
explicit BufferedInputStream(
std::unique_ptr<crypto::tink::InputStream> input_stream);
~BufferedInputStream() override;
crypto::tink::util::StatusOr<int> Next(const void** data) override;
void BackUp(int count) override;
int64_t Position() const override;
// Rewinds this stream to the beginning (if rewinding is still enabled).
crypto::tink::util::Status Rewind();
// Disables rewinding.
void DisableRewinding();
private:
std::unique_ptr<crypto::tink::InputStream> input_stream_;
bool direct_access_; // true iff we don't buffer any data any more
// The fields below are valid and in use iff direct_access_ is false.
// Once direct_access_ becomes true, all the calls to this stream's methods
// are directly relayed to methods of input_stream_.
crypto::tink::util::Status status_;
std::vector<uint8_t> buffer_;
bool after_rewind_; // true iff no Next has been called after rewind
bool rewinding_enabled_; // true iff this stream can be rewound
int64_t position_; // current position in the stream (from the beginning)
// Counters that describe the state of the data in buffer_.
int count_in_buffer_; // # of bytes available in buffer_
int count_backedup_; // # of bytes available in buffer_ that were backed up
int buffer_offset_; // offset at which the returned bytes start in buffer_
};
} // namespace streamingaead
} // namespace tink
} // namespace crypto
#endif // TINK_STREAMINGAEAD_BUFFERED_INPUT_STREAM_H_
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