appstreambuf.cpp

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/*
 * appstreambuf.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/config.h"
#include "ibrcommon/appstreambuf.h"

namespace ibrcommon
{
        appstreambuf::appstreambuf(const std::string &command, appstreambuf::Mode mode)
         : m_buf( BUF_SIZE+1 )
        {
                // execute the command
                if (mode == MODE_READ)
                {
                        setg(0, 0, 0);
                        _handle = popen(command.c_str(), "r");
                }
                else
                {
                        setp( &m_buf[0], &m_buf[0] + (m_buf.size() - 1) );
                        _handle = popen(command.c_str(), "w");
                }
        }

        appstreambuf::~appstreambuf()
        {
                // close the handle
                pclose(_handle);
        }

        std::char_traits<char>::int_type appstreambuf::underflow()
        {
                // read the stdout of the process
                size_t ret = 0;

                if (feof(_handle))
                        return std::char_traits<char>::eof();

                ret = fread(&m_buf[0], sizeof(char), m_buf.size(), _handle);

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

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

        int appstreambuf::sync()
        {
                int ret = std::char_traits<char>::eq_int_type(this->overflow(std::char_traits<char>::eof()),
                                std::char_traits<char>::eof()) ? -1 : 0;

                return ret;
        }

        std::char_traits<char>::int_type appstreambuf::overflow( std::char_traits<char>::int_type m )
        {
                char *ibegin = pbase();
                char *iend = pptr();

                // if there is nothing to send, just return
                if ( iend <= ibegin ) return std::char_traits<char>::not_eof(m);

                // mark the buffer as free
                setp( &m_buf[0], &m_buf[0] + (m_buf.size() - 1) );

                if(!std::char_traits<char>::eq_int_type(m, std::char_traits<char>::eof())) {
                        *iend++ = std::char_traits<char>::to_char_type(m);
                }

                const size_t avail_data = (iend - ibegin);

                // write the data
                if (fwrite(ibegin, sizeof(char), avail_data, _handle) != avail_data)
                {
                        return std::char_traits<char>::eof();
                }

                return std::char_traits<char>::not_eof(m);
        }
}