Line data    Source code

       1             : /*
       2             :   Zipios -- a small C++ library that provides easy access to .zip files.
       3             : 
       4             :   Copyright (C) 2000-2007  Thomas Sondergaard
       5             :   Copyright (c) 2015-2022  Made to Order Software Corp.  All Rights Reserved
       6             : 
       7             :   This library is free software; you can redistribute it and/or
       8             :   modify it under the terms of the GNU Lesser General Public
       9             :   License as published by the Free Software Foundation; either
      10             :   version 2.1 of the License, or (at your option) any later version.
      11             : 
      12             :   This library is distributed in the hope that it will be useful,
      13             :   but WITHOUT ANY WARRANTY; without even the implied warranty of
      14             :   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      15             :   Lesser General Public License for more details.
      16             : 
      17             :   You should have received a copy of the GNU Lesser General Public
      18             :   License along with this library; if not, write to the Free Software
      19             :   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
      20             : */
      21             : 
      22             : /** \file
      23             :  * \brief This file is the implementation of zipios::GZIPOutputStreambuf class.
      24             :  *
      25             :  * This class is an output stream filter which knows how to creates a .gz
      26             :  * file from the data you write to it.
      27             :  *
      28             :  * The compression makes use of the zlib library.
      29             :  */
      30             : 
      31             : #include "gzipoutputstreambuf.hpp"
      32             : 
      33             : #include "zipios/zipiosexceptions.hpp"
      34             : 
      35             : 
      36             : namespace zipios
      37             : {
      38             : 
      39             : /** \class GZIPOutputStreambuf
      40             :  * \brief Save the output stream buffer.
      41             :  *
      42             :  * This class is used to output the data of a file in a gzip stream
      43             :  * including the necessary header and footer.
      44             :  */
      45             : 
      46             : 
      47             : /** \brief Initialize a GZIPOutputStreambuf object.
      48             :  *
      49             :  * A newly constructed GZIPOutputStreambuf is ready to accept data.
      50             :  *
      51             :  * \param[in,out] outbuf  The streambuf to use for output.
      52             :  * \param[in] compression_level  The compression level to use to compress.
      53             :  */
      54           0 : GZIPOutputStreambuf::GZIPOutputStreambuf(std::streambuf * outbuf, FileEntry::CompressionLevel compression_level)
      55           0 :     : DeflateOutputStreambuf(outbuf)
      56             : {
      57           0 :     if(!init(compression_level))
      58             :     {
      59           0 :         throw InvalidStateException("GZIPOutputStreambuf::GZIPOutputStreambuf() failed initializing zlib.");
      60             :     }
      61           0 : }
      62             : 
      63             : 
      64             : /** \brief Ensures that the stream gets closed properly.
      65             :  *
      66             :  * This function makes sure that the stream gets closed properly
      67             :  * which means that the compress terminates by calling finish()
      68             :  * and the streams get closed.
      69             :  */
      70           0 : GZIPOutputStreambuf::~GZIPOutputStreambuf()
      71             : {
      72           0 :     finish();
      73           0 : }
      74             : 
      75             : 
      76           0 : void GZIPOutputStreambuf::setFilename(std::string const & filename)
      77             : {
      78           0 :     m_filename = filename;
      79           0 : }
      80             : 
      81             : 
      82           0 : void GZIPOutputStreambuf::setComment(std::string const & comment)
      83             : {
      84           0 :     m_comment = comment;
      85           0 : }
      86             : 
      87             : 
      88             : /** \brief Close the stream.
      89             :  *
      90             :  * This function ensures that the streams get closed.
      91             :  */
      92           0 : void GZIPOutputStreambuf::close()
      93             : {
      94           0 :     finish();
      95           0 : }
      96             : 
      97             : 
      98             : /** \brief Finishes the compression.
      99             :  *
     100             :  * Write whatever is still necessary and close the streams.
     101             :  */
     102           0 : void GZIPOutputStreambuf::finish()
     103             : {
     104           0 :     if(!m_open)
     105             :     {
     106           0 :         return;
     107             :     }
     108           0 :     m_open = false;
     109             : 
     110           0 :     closeStream();
     111           0 :     writeTrailer();
     112             : }
     113             : 
     114             : 
     115           0 : int GZIPOutputStreambuf::overflow(int c)
     116             : {
     117           0 :     if(!m_open)
     118             :     {
     119           0 :         writeHeader();
     120           0 :         m_open = true;
     121             :     }
     122             : 
     123           0 :     return DeflateOutputStreambuf::overflow(c);
     124             : }
     125             : 
     126             : 
     127           0 : int GZIPOutputStreambuf::sync()
     128             : {
     129           0 :     return DeflateOutputStreambuf::sync();
     130             : }
     131             : 
     132             : 
     133           0 : void GZIPOutputStreambuf::writeHeader()
     134             : {
     135             :     unsigned char const flg(
     136           0 :                   (m_filename.empty() ? 0x00 : 0x08)
     137           0 :                 | (m_comment.empty()  ? 0x00 : 0x10)
     138           0 :             );
     139             : 
     140             :     /** \TODO
     141             :      * We need to know of the last modification time instead of
     142             :      * saving all zeros for MTIME values.
     143             :      */
     144             : 
     145             :     /** \todo:
     146             :      * I am thinking that the OS should be 3 under Unices.
     147             :      */
     148             : 
     149           0 :     std::ostream os(m_outbuf);
     150           0 :     os << static_cast<unsigned char>(0x1f);  // Magic #
     151           0 :     os << static_cast<unsigned char>(0x8b);  // Magic #
     152           0 :     os << static_cast<unsigned char>(0x08);  // Deflater.DEFLATED
     153           0 :     os << flg;                               // FLG
     154           0 :     os << static_cast<unsigned char>(0x00);  // MTIME
     155           0 :     os << static_cast<unsigned char>(0x00);  // MTIME
     156           0 :     os << static_cast<unsigned char>(0x00);  // MTIME
     157           0 :     os << static_cast<unsigned char>(0x00);  // MTIME
     158           0 :     os << static_cast<unsigned char>(0x00);  // XFLG
     159           0 :     os << static_cast<unsigned char>(0x00);  // OS
     160             : 
     161           0 :     if(!m_filename.empty())
     162             :     {
     163           0 :         os << m_filename.c_str();             // Filename
     164           0 :         os << static_cast<unsigned char>(0x00);
     165             :     }
     166             : 
     167           0 :     if(!m_comment.empty())
     168             :     {
     169           0 :         os << m_comment.c_str();              // Comment
     170           0 :         os << static_cast<unsigned char>(0x00);
     171             :     }
     172           0 : }
     173             : 
     174             : 
     175           0 : void GZIPOutputStreambuf::writeTrailer()
     176             : {
     177             :     // write the CRC32 and Size at the end of the file
     178           0 :     writeInt(getCrc32());
     179           0 :     writeInt(getSize());
     180           0 : }
     181             : 
     182             : 
     183           0 : void GZIPOutputStreambuf::writeInt(uint32_t i)
     184             : {
     185             :     /** \todo: add support for 64 bit files if it exists? */
     186           0 :     std::ostream os(m_outbuf);
     187           0 :     os << static_cast<unsigned char>( i        & 0xFF);
     188           0 :     os << static_cast<unsigned char>((i >>  8) & 0xFF);
     189           0 :     os << static_cast<unsigned char>((i >> 16) & 0xFF);
     190           0 :     os << static_cast<unsigned char>((i >> 24) & 0xFF);
     191           0 : }
     192             : 
     193             : 
     194             : } // zipios namespace
     195             : 
     196             : // Local Variables:
     197             : // mode: cpp
     198             : // indent-tabs-mode: nil
     199             : // c-basic-offset: 4
     200             : // tab-width: 4
     201             : // End:
     202             : 
     203             : // vim: ts=4 sw=4 et