zipinputstreambuf.cpp

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/*
  Zipios -- a small C++ library that provides easy access to .zip files.
 
  Copyright (C) 2000-2007  Thomas Sondergaard
  Copyright (c) 2015-2022  Made to Order Software Corp.  All Rights Reserved
 
  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.
 
  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.
 
  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#include "zipinputstreambuf.hpp"
 
#include "zipios/zipiosexceptions.hpp"
 
#include <algorithm>
 
 
namespace zipios
{
 
 
ZipInputStreambuf::ZipInputStreambuf(std::streambuf * inbuf, offset_t start_pos)
    : InflateInputStreambuf(inbuf, start_pos)
{
    // read the zip local header
    std::istream is(m_inbuf); // istream does not destroy the streambuf.
    is.exceptions(std::ios::eofbit | std::ios::failbit | std::ios::badbit);
 
    // if the read fails in any way it will throw
    m_current_entry.read(is);
    if(m_current_entry.isValid() && m_current_entry.hasTrailingDataDescriptor())
    {
        throw FileCollectionException("Trailing data descriptor in zip file not supported");
    }
 
    switch(m_current_entry.getMethod())
    {
    case StorageMethod::DEFLATED:
        reset() ; // reset inflatestream data structures
//std::cerr << "deflated" << std::endl;
        break;
 
    case StorageMethod::STORED:
        m_remain = m_current_entry.getSize();
        // Force underflow on first read:
        setg(&m_outvec[0], &m_outvec[0] + getBufferSize(), &m_outvec[0] + getBufferSize());
//std::cerr << "stored" << std::endl;
        break;
 
    default:
        // file not supported... sorry!
        throw FileCollectionException("Unsupported compression format");
 
    }
}
 
 
ZipInputStreambuf::~ZipInputStreambuf()
{
}
 
 
std::streambuf::int_type ZipInputStreambuf::underflow()
{
    switch(m_current_entry.getMethod())
    {
    case StorageMethod::DEFLATED:
        // inflate class takes care of it in this case
        return InflateInputStreambuf::underflow();
 
    case StorageMethod::STORED:
    {
        // Ok, we are STORED, so we handle it ourselves.
        offset_t const num_b(std::min(m_remain, static_cast<offset_t>(getBufferSize())));
        std::streamsize const g(m_inbuf->sgetn(&m_outvec[0], num_b));
        setg(&m_outvec[0], &m_outvec[0], &m_outvec[0] + g);
        m_remain -= g;
        if(g > 0)
        {
            // we got some data, return it
            return traits_type::to_int_type(*gptr());
        }
 
        // documentation says to return EOF if no data available
        return traits_type::eof();
    }
 
    default: // LCOV_EXCL_LINE
        // This should NEVER be reached or the constructor let something
        // go through that should not have gone through
        throw std::logic_error("ZipInputStreambuf::underflow(): unknown storage method"); // LCOV_EXCL_LINE
 
    }
}
 
 
} // namespace
 
// Local Variables:
// mode: cpp
// indent-tabs-mode: nil
// c-basic-offset: 4
// tab-width: 4
// End:
 
// vim: ts=4 sw=4 et