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tif_stream.cxx

/* $Id: tif_stream.cxx,v 1.5 2005/07/26 08:11:13 dron Exp $ */

/*
 * Copyright (c) 1988-1996 Sam Leffler
 * Copyright (c) 1991-1996 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */

/*
 * TIFF Library UNIX-specific Routines.
 */
#include "tiffiop.h"
#include <iostream>

using namespace std;

class tiffis_data
{
  public:

      istream     *myIS;
        long      myStreamStartPos;
};

class tiffos_data
{
  public:

      ostream     *myOS;
      long  myStreamStartPos;
};

static tsize_t
_tiffosReadProc(thandle_t, tdata_t, tsize_t)
{
        return 0;
}

static tsize_t
_tiffisReadProc(thandle_t fd, tdata_t buf, tsize_t size)
{
        tiffis_data     *data = (tiffis_data *)fd;

        data->myIS->read((char *)buf, (int)size);

        return data->myIS->gcount();
}

static tsize_t
_tiffosWriteProc(thandle_t fd, tdata_t buf, tsize_t size)
{
      tiffos_data *data = (tiffos_data *)fd;
      ostream           *os = data->myOS;
      int         pos = os->tellp();

      os->write((const char *)buf, size);

      return ((int)os->tellp()) - pos;
}

static tsize_t
_tiffisWriteProc(thandle_t, tdata_t, tsize_t)
{
      return 0;
}

static toff_t
_tiffosSeekProc(thandle_t fd, toff_t off, int whence)
{
      tiffos_data *data = (tiffos_data *)fd;
      ostream     *os = data->myOS;

      // if the stream has already failed, don't do anything
      if( os->fail() )
            return os->tellp();

      switch(whence) {
      case SEEK_SET:
          os->seekp(data->myStreamStartPos + off, ios::beg);
            break;
      case SEEK_CUR:
            os->seekp(off, ios::cur);
            break;
      case SEEK_END:
            os->seekp(off, ios::end);
            break;
      }

      // Attempt to workaround problems with seeking past the end of the
      // stream.  ofstream doesn't have a problem with this but
      // ostrstream/ostringstream does. In that situation, add intermediate
      // '\0' characters.
      if( os->fail() ) {
            ios::iostate      old_state;
            toff_t            origin;

            old_state = os->rdstate();
            // reset the fail bit or else tellp() won't work below
            os->clear(os->rdstate() & ~ios::failbit);
            switch( whence ) {
                  case SEEK_SET:
                        origin = data->myStreamStartPos;
                        break;
                  case SEEK_CUR:
                        origin = os->tellp();
                        break;
                  case SEEK_END:
                        os->seekp(0, ios::end);
                        origin = os->tellp();
                        break;
            }
            // restore original stream state
            os->clear(old_state);   

            // only do something if desired seek position is valid
            if( origin + off > data->myStreamStartPos ) {
                  toff_t      num_fill;

                  // clear the fail bit 
                  os->clear(os->rdstate() & ~ios::failbit);

                  // extend the stream to the expected size
                  os->seekp(0, ios::end);
                  num_fill = origin + off - (toff_t)os->tellp();
                  for( toff_t i = 0; i < num_fill; i++ )
                        os->put('\0');

                  // retry the seek
                  os->seekp(origin + off, ios::beg);
            }
      }

      return os->tellp();
}

static toff_t
_tiffisSeekProc(thandle_t fd, toff_t off, int whence)
{
      tiffis_data *data = (tiffis_data *)fd;

      switch(whence) {
      case SEEK_SET:
            data->myIS->seekg(data->myStreamStartPos + off, ios::beg);
            break;
      case SEEK_CUR:
            data->myIS->seekg(off, ios::cur);
            break;
      case SEEK_END:
            data->myIS->seekg(off, ios::end);
            break;
      }

      return ((long)data->myIS->tellg()) - data->myStreamStartPos;
}

static toff_t
_tiffosSizeProc(thandle_t fd)
{
      tiffos_data *data = (tiffos_data *)fd;
      ostream           *os = data->myOS;
      toff_t            pos = os->tellp();
      toff_t            len;

      os->seekp(0, ios::end);
      len = os->tellp();
      os->seekp(pos);

      return len;
}

static toff_t
_tiffisSizeProc(thandle_t fd)
{
      tiffis_data *data = (tiffis_data *)fd;
      int         pos = data->myIS->tellg();
      int         len;

      data->myIS->seekg(0, ios::end);
      len = data->myIS->tellg();
      data->myIS->seekg(pos);

      return len;
}

static int
_tiffosCloseProc(thandle_t fd)
{
      // Our stream was not allocated by us, so it shouldn't be closed by us.
      delete (tiffos_data *)fd;
      return 0;
}

static int
_tiffisCloseProc(thandle_t fd)
{
      // Our stream was not allocated by us, so it shouldn't be closed by us.
      delete (tiffis_data *)fd;
      return 0;
}

static int
_tiffDummyMapProc(thandle_t , tdata_t* , toff_t* )
{
      return (0);
}

static void
_tiffDummyUnmapProc(thandle_t , tdata_t , toff_t )
{
}

/*
 * Open a TIFF file descriptor for read/writing.
 */
static TIFF*
_tiffStreamOpen(const char* name, const char* mode, void *fd)
{
      TIFF* tif;

      if( strchr(mode, 'w') ) {
            tiffos_data *data = new tiffos_data;
            data->myOS = (ostream *)fd;
            data->myStreamStartPos = data->myOS->tellp();

            // Open for writing.
            tif = TIFFClientOpen(name, mode,
                        (thandle_t) data,
                        _tiffosReadProc, _tiffosWriteProc,
                        _tiffosSeekProc, _tiffosCloseProc,
                        _tiffosSizeProc,
                        _tiffDummyMapProc, _tiffDummyUnmapProc);
      } else {
            tiffis_data *data = new tiffis_data;
            data->myIS = (istream *)fd;
            data->myStreamStartPos = data->myIS->tellg();
            // Open for reading.
            tif = TIFFClientOpen(name, mode,
                        (thandle_t) data,
                        _tiffisReadProc, _tiffisWriteProc,
                        _tiffisSeekProc, _tiffisCloseProc,
                        _tiffisSizeProc,
                        _tiffDummyMapProc, _tiffDummyUnmapProc);
      }

      return (tif);
}

TIFF*
TIFFStreamOpen(const char* name, ostream *os)
{
      // If os is either a ostrstream or ostringstream, and has no data
      // written to it yet, then tellp() will return -1 which will break us.
      // We workaround this by writing out a dummy character and
      // then seek back to the beginning.
      if( !os->fail() && (int)os->tellp() < 0 ) {
            *os << '\0';
            os->seekp(0);
      }

      // NB: We don't support mapped files with streams so add 'm'
      return _tiffStreamOpen(name, "wm", os);
}

TIFF*
TIFFStreamOpen(const char* name, istream *is)
{
      // NB: We don't support mapped files with streams so add 'm'
      return _tiffStreamOpen(name, "rm", is);
}

/* vim: set ts=8 sts=8 sw=8 noet: */

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