gzstream.cc

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// ============================================================================
// 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: 1.7 $
// Revision_date : $Date: 2003/01/08 14:41:27 $
// Author(s)     : Deepak Bandyopadhyay, Lutz Kettner
//
// Standard streambuf implementation following Nicolai Josuttis, "The
// Standard C++ Library".
// ============================================================================
 
#include "gzstream.h"
#include <cassert>
#include <cstring>  // for memcpy
 
#ifdef GZSTREAM_NAMESPACE
namespace GZSTREAM_NAMESPACE {
#endif
 
// ----------------------------------------------------------------------------
// 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
  assert(gptr() != NULL);
  int n_putback = (int)(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 = (int)(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() = (char)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 gz_open_mode) {
  if (!buf.open(name, gz_open_mode)) clear(rdstate() | std::ios::badbit);
}
 
void gzstreambase::close() {
  if (buf.is_open())
    if (!buf.close()) clear(rdstate() | std::ios::badbit);
}
 
#ifdef GZSTREAM_NAMESPACE
}  // namespace GZSTREAM_NAMESPACE
#endif
 
// ============================================================================
// EOF //