InputCipherStream.cpp

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/*
 * InputCipherStream.cpp
 *
 * Copyright (C) 2011 IBR, TU Braunschweig
 *
 * Written-by: Johannes Morgenroth <morgenroth@ibr.cs.tu-bs.de>
 *
 * 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.
 *
 */

#include "ibrcommon/ssl/InputCipherStream.h"

namespace ibrcommon
{
        InputCipherStream::InputCipherStream(std::istream &stream, const CipherMode mode, const size_t buffer)
         : std::istream(this), _stream(stream), _mode(mode), data_buf_(buffer), data_size_(buffer)
        {
                // Initialize get pointer.  This should be zero so that underflow is called upon first read.
                setg(0, 0, 0);
                setp(&data_buf_[0], &data_buf_[0] + data_size_ - 1);
        }

        InputCipherStream::~InputCipherStream()
        {
        }

        std::char_traits<char>::int_type InputCipherStream::underflow()
        {
                _stream.read(&data_buf_[0], data_size_);
                int bytes = _stream.gcount();

                if (bytes == 0)
                {
                        return std::char_traits<char>::eof();
                }

                // Since the input buffer content is now valid (or is new)
                // the get pointer should be initialized (or reset).
                setg(&data_buf_[0], &data_buf_[0], &data_buf_[0] + bytes);

                return std::char_traits<char>::not_eof(data_buf_[0]);
        }
}