tif_stream.cxx

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/*
 * 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>
 
#ifndef __VMS
using namespace std;
#endif
 
/*
  ISO C++ uses a 'std::streamsize' type to define counts.  This makes
  it similar to, (but perhaps not the same as) size_t.
 
  The std::ios::pos_type is used to represent stream positions as used
  by tellg(), tellp(), seekg(), and seekp().  This makes it similar to
  (but perhaps not the same as) 'off_t'.  The std::ios::streampos type
  is used for character streams, but is documented to not be an
  integral type anymore, so it should *not* be assigned to an integral
  type.
 
  The std::ios::off_type is used to specify relative offsets needed by
  the variants of seekg() and seekp() which accept a relative offset
  argument.
 
  Useful prototype knowledge:
 
  Obtain read position
    ios::pos_type basic_istream::tellg()
 
  Set read position
    basic_istream& basic_istream::seekg(ios::pos_type)
    basic_istream& basic_istream::seekg(ios::off_type, ios_base::seekdir)
 
  Read data
    basic_istream& istream::read(char *str, streamsize count)
 
  Number of characters read in last unformatted read
    streamsize istream::gcount();
 
  Obtain write position
    ios::pos_type basic_ostream::tellp()
 
  Set write position
    basic_ostream& basic_ostream::seekp(ios::pos_type)
    basic_ostream& basic_ostream::seekp(ios::off_type, ios_base::seekdir)
 
  Write data
    basic_ostream& ostream::write(const char *str, streamsize count)
*/
 
struct tiffis_data;
struct tiffos_data;
 
extern "C" {
 
    static tmsize_t _tiffosReadProc(thandle_t, void*, tmsize_t);
    static tmsize_t _tiffisReadProc(thandle_t fd, void* buf, tmsize_t size);
    static tmsize_t _tiffosWriteProc(thandle_t fd, void* buf, tmsize_t size);
    static tmsize_t _tiffisWriteProc(thandle_t, void*, tmsize_t);
    static uint64   _tiffosSeekProc(thandle_t fd, uint64 off, int whence);
    static uint64   _tiffisSeekProc(thandle_t fd, uint64 off, int whence);
    static uint64   _tiffosSizeProc(thandle_t fd);
    static uint64   _tiffisSizeProc(thandle_t fd);
    static int      _tiffosCloseProc(thandle_t fd);
    static int      _tiffisCloseProc(thandle_t fd);
    static int  _tiffDummyMapProc(thandle_t , void** base, toff_t* size );
    static void     _tiffDummyUnmapProc(thandle_t , void* base, toff_t size );
    static TIFF*    _tiffStreamOpen(const char* name, const char* mode, void *fd);
 
struct tiffis_data
{
    istream *stream;
        ios::pos_type start_pos;
};
 
struct tiffos_data
{
    ostream *stream;
    ios::pos_type start_pos;
};
 
static tmsize_t
_tiffosReadProc(thandle_t, void*, tmsize_t)
{
        return 0;
}
 
static tmsize_t
_tiffisReadProc(thandle_t fd, void* buf, tmsize_t size)
{
        tiffis_data *data = reinterpret_cast<tiffis_data *>(fd);
 
        // Verify that type does not overflow.
        streamsize request_size = size;
        if (static_cast<tmsize_t>(request_size) != size)
          return static_cast<tmsize_t>(-1);
 
        data->stream->read((char *) buf, request_size);
 
        return static_cast<tmsize_t>(data->stream->gcount());
}
 
static tmsize_t
_tiffosWriteProc(thandle_t fd, void* buf, tmsize_t size)
{
    tiffos_data *data = reinterpret_cast<tiffos_data *>(fd);
    ostream     *os = data->stream;
    ios::pos_type   pos = os->tellp();
 
        // Verify that type does not overflow.
        streamsize request_size = size;
        if (static_cast<tmsize_t>(request_size) != size)
          return static_cast<tmsize_t>(-1);
 
    os->write(reinterpret_cast<const char *>(buf), request_size);
 
    return static_cast<tmsize_t>(os->tellp() - pos);
}
 
static tmsize_t
_tiffisWriteProc(thandle_t, void*, tmsize_t)
{
    return 0;
}
 
static uint64
_tiffosSeekProc(thandle_t fd, uint64 off, int whence)
{
    tiffos_data *data = reinterpret_cast<tiffos_data *>(fd);
    ostream     *os = data->stream;
 
    // if the stream has already failed, don't do anything
    if( os->fail() )
        return static_cast<uint64>(-1);
 
    switch(whence) {
    case SEEK_SET:
        {
            // Compute 64-bit offset
            uint64 new_offset = static_cast<uint64>(data->start_pos) + off;
 
            // Verify that value does not overflow
            ios::off_type offset = static_cast<ios::off_type>(new_offset);
            if (static_cast<uint64>(offset) != new_offset)
                return static_cast<uint64>(-1);
            
            os->seekp(offset, ios::beg);
        break;
        }
    case SEEK_CUR:
        {
            // Verify that value does not overflow
            ios::off_type offset = static_cast<ios::off_type>(off);
            if (static_cast<uint64>(offset) != off)
                return static_cast<uint64>(-1);
 
            os->seekp(offset, ios::cur);
            break;
        }
    case SEEK_END:
        {
            // Verify that value does not overflow
            ios::off_type offset = static_cast<ios::off_type>(off);
            if (static_cast<uint64>(offset) != off)
                return static_cast<uint64>(-1);
 
            os->seekp(offset, 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() ) {
#ifdef __VMS
        int     old_state;
#else
        ios::iostate    old_state;
#endif
        ios::pos_type   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:
                        default:
                origin = data->start_pos;
                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( (static_cast<uint64>(origin) + off) > static_cast<uint64>(data->start_pos) ) {
            uint64  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 = (static_cast<uint64>(origin)) + off - os->tellp();
            for( uint64 i = 0; i < num_fill; i++ )
                os->put('\0');
 
            // retry the seek
            os->seekp(static_cast<ios::off_type>(static_cast<uint64>(origin) + off), ios::beg);
        }
    }
 
    return static_cast<uint64>(os->tellp());
}
 
static uint64
_tiffisSeekProc(thandle_t fd, uint64 off, int whence)
{
    tiffis_data *data = reinterpret_cast<tiffis_data *>(fd);
 
    switch(whence) {
    case SEEK_SET:
        {
            // Compute 64-bit offset
            uint64 new_offset = static_cast<uint64>(data->start_pos) + off;
            
            // Verify that value does not overflow
            ios::off_type offset = static_cast<ios::off_type>(new_offset);
            if (static_cast<uint64>(offset) != new_offset)
                return static_cast<uint64>(-1);
 
            data->stream->seekg(offset, ios::beg);
            break;
        }
    case SEEK_CUR:
        {
            // Verify that value does not overflow
            ios::off_type offset = static_cast<ios::off_type>(off);
            if (static_cast<uint64>(offset) != off)
                return static_cast<uint64>(-1);
 
            data->stream->seekg(offset, ios::cur);
            break;
        }
    case SEEK_END:
        {
            // Verify that value does not overflow
            ios::off_type offset = static_cast<ios::off_type>(off);
            if (static_cast<uint64>(offset) != off)
                return static_cast<uint64>(-1);
 
            data->stream->seekg(offset, ios::end);
            break;
        }
    }
 
    return (uint64) (data->stream->tellg() - data->start_pos);
}
 
static uint64
_tiffosSizeProc(thandle_t fd)
{
    tiffos_data *data = reinterpret_cast<tiffos_data *>(fd);
    ostream     *os = data->stream;
    ios::pos_type   pos = os->tellp();
    ios::pos_type   len;
 
    os->seekp(0, ios::end);
    len = os->tellp();
    os->seekp(pos);
 
    return (uint64) len;
}
 
static uint64
_tiffisSizeProc(thandle_t fd)
{
    tiffis_data *data = reinterpret_cast<tiffis_data *>(fd);
    ios::pos_type   pos = data->stream->tellg();
    ios::pos_type   len;
 
    data->stream->seekg(0, ios::end);
    len = data->stream->tellg();
    data->stream->seekg(pos);
 
    return (uint64) len;
}
 
static int
_tiffosCloseProc(thandle_t fd)
{
    // Our stream was not allocated by us, so it shouldn't be closed by us.
    delete reinterpret_cast<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 reinterpret_cast<tiffis_data *>(fd);
    return 0;
}
 
static int
_tiffDummyMapProc(thandle_t , void** base, toff_t* size )
{
    (void) base;
    (void) size;
    return (0);
}
 
static void
_tiffDummyUnmapProc(thandle_t , void* base, toff_t size )
{
    (void) base;
    (void) size;
}
 
/*
 * 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->stream = reinterpret_cast<ostream *>(fd);
        data->start_pos = data->stream->tellp();
 
        // Open for writing.
        tif = TIFFClientOpen(name, mode,
                reinterpret_cast<thandle_t>(data),
                _tiffosReadProc,
                                _tiffosWriteProc,
                _tiffosSeekProc,
                                _tiffosCloseProc,
                _tiffosSizeProc,
                _tiffDummyMapProc,
                                _tiffDummyUnmapProc);
        if (!tif) {
            delete data;
        }
    } else {
        tiffis_data *data = new tiffis_data;
        data->stream = reinterpret_cast<istream *>(fd);
        data->start_pos = data->stream->tellg();
        // Open for reading.
        tif = TIFFClientOpen(name, mode,
                reinterpret_cast<thandle_t>(data),
                _tiffisReadProc,
                                _tiffisWriteProc,
                _tiffisSeekProc,
                                _tiffisCloseProc,
                _tiffisSizeProc,
                _tiffDummyMapProc,
                                _tiffDummyUnmapProc);
        if (!tif) {
            delete data;
        }
    }
 
    return (tif);
}
 
} /* extern "C" */
 
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() && static_cast<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: */
/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 8
 * fill-column: 78
 * End:
 */