A PGLIB lo_export function for Win32

Well, I'm making progress in my attempt to incorporate large objects in my NT
application.  At this point I can export an object but the resulting file is
corrupt.  The object within the database is not corrupt.  I have checked by
using the normal lo_export function.  Following is the section of code used to
create the file.  I have removed the error checks for readability here.  The
normal C function calls open(), write(), and close() as well as the single
call to lo_export() produce  the corrupted file,  the commented out Win32
calls cause a memory fault.


  res = PQexec(conn, "begin");
  PQclear(res);

  lobj_fd = lo_open(conn, lobjId, INV_READ);

/*  lo_export(conn, lobjId, filename);  */

  fd = open(filename, OF_CREATE | OF_WRITE, 0666);

/*  fd = CreateFile(filename, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_DELETE
| FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL, NULL); */

  while ((nbytes = lo_read(conn, lobj_fd, buf, BUFSIZE)) > 0)
  {
    tmp = write(fd, buf, nbytes);

/*    tmp =WriteFile(fd, buf, nbytes, BUFSIZE, NULL); */

  }

/*  (void) lo_close(conn, lobj_fd); */

  (void) close(fd);
  (void) CloseHandle(fd);

  res = PQexec(conn, "end");
  PQclear(res);
  PQfinish(conn);