gzstream.cpp

// ============================================================================
// gzstream, C++ iostream classes wrapping the zlib compression library.
// Copyright (C) 2001  Deepak Bandyopadhyay, Lutz Kettner
//
// 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
// ============================================================================
//
// File          : gzstream.C
// Revision      : $Revision$
// Revision_date : $Date$
// Author(s)     : Deepak Bandyopadhyay, Lutz Kettner
//
// Standard streambuf implementation following Nicolai Josuttis, "The
// Standard C++ Library".
// ============================================================================
 
#include "io/gzstream.hpp"
 
#include <cstring>  // for memcpy
#include <iostream>
 
namespace OpenMD {
 
  // ----------------------------------------------------------------------------
  // Internal classes to implement gzstream. See header file for user classes.
  // ----------------------------------------------------------------------------
 
  // --------------------------------------
  // class gzstreambuf:
  // --------------------------------------
 
  gzstreambuf* gzstreambuf::open(const char* name, int open_mode) {
    if (is_open()) return (gzstreambuf*)0;
    mode = open_mode;
    // no append nor read/write mode
    if ((mode & std::ios::ate) || (mode & std::ios::app) ||
        ((mode & std::ios::in) && (mode & std::ios::out)))
      return (gzstreambuf*)0;
    char fmode[10];
    char* fmodeptr = fmode;
    if (mode & std::ios::in)
      *fmodeptr++ = 'r';
    else if (mode & std::ios::out)
      *fmodeptr++ = 'w';
    *fmodeptr++ = 'b';
    *fmodeptr   = '\0';
    file        = gzopen(name, fmode);
    if (file == 0) return (gzstreambuf*)0;
    opened = 1;
    return this;
  }
 
  gzstreambuf* gzstreambuf::close() {
    if (is_open()) {
      sync();
      opened = 0;
      if (gzclose(file) == Z_OK) return this;
    }
    return (gzstreambuf*)0;
  }
 
  int gzstreambuf::underflow() {  // used for input buffer only
    if (gptr() && (gptr() < egptr()))
      return *reinterpret_cast<unsigned char*>(gptr());
 
    if (!(mode & std::ios::in) || !opened) return EOF;
    // Josuttis' implementation of inbuf
    int n_putback = gptr() - eback();
    if (n_putback > 4) n_putback = 4;
    memcpy(buffer + (4 - n_putback), gptr() - n_putback, n_putback);
 
    int num = gzread(file, buffer + 4, bufferSize - 4);
    if (num <= 0)  // ERROR or EOF
      return EOF;
 
    // reset buffer pointers
    setg(buffer + (4 - n_putback),  // beginning of putback area
         buffer + 4,                // read position
         buffer + 4 + num);         // end of buffer
 
    // return next character
    return *reinterpret_cast<unsigned char*>(gptr());
  }
 
  int gzstreambuf::flush_buffer() {
    // Separate the writing of the buffer from overflow() and
    // sync() operation.
    int w = pptr() - pbase();
    if (gzwrite(file, pbase(), w) != w) return EOF;
    pbump(-w);
    return w;
  }
 
  int gzstreambuf::overflow(int c) {  // used for output buffer only
    if (!(mode & std::ios::out) || !opened) return EOF;
    if (c != EOF) {
      *pptr() = c;
      pbump(1);
    }
    if (flush_buffer() == EOF) return EOF;
    return c;
  }
 
  int gzstreambuf::sync() {
    // Changed to use flush_buffer() instead of overflow( EOF)
    // which caused improper behavior with std::endl and flush(),
    // bug reported by Vincent Ricard.
    if (pptr() && pptr() > pbase()) {
      if (flush_buffer() == EOF) return -1;
    }
    return 0;
  }
 
  // --------------------------------------
  // class gzstreambase:
  // --------------------------------------
 
  gzstreambase::gzstreambase(const char* name, int mode) {
    init(&buf);
    open(name, mode);
  }
 
  gzstreambase::~gzstreambase() { buf.close(); }
 
  void gzstreambase::open(const char* name, int open_mode) {
    if (!buf.open(name, open_mode)) clear(rdstate() | std::ios::badbit);
  }
 
  void gzstreambase::close() {
    if (buf.is_open())
      if (!buf.close()) clear(rdstate() | std::ios::badbit);
  }
 
}  // namespace OpenMD