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__bw_prcv__.cc

// Copyright (C) 2007 Olaf Till <olaf.till@uni-jena.de>

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.

// This program 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 General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

#include <octave/oct.h>
#include <octave/load-save.h>
#include <octave/ls-oct-binary.h>
#include <octave/oct-stream.h>
#include <octave/oct-map.h>

DEFUN_DLD (__bw_prcv__, args, nargout, "__bw_prcv__ (pd)\n\
Reads one variable from pipe stream 'pd'.\n\
The variable must have been coded in Octaves binary format,\n\
including a header. This can be done by 'psend ()'.\n\
If EOF is met at start of reading, 0 is returned, so you\n\
can test if 'ismatrix (return_value)' as an alternative to\n\
call 'feof ()' afterwards. If EOF is met later in reading,\n\
it causes an error.\n\
Normally, a structure is returned with the variable under its name\n\
in a single field. Originally, with no output arguments, the variable was\n\
installed into memory, but this has been disabled.\n\
\n\
This function may change and is internal to the parallel package.\n")
{
      octave_value retval;
      Octave_map retstruct;

      if (args.length () != 1) {
            error ("__bw_prcv__: exactly one argument required\n");
            return retval;
      }
      octave_stream is = octave_stream_list::lookup (args(0), "__bw_prcv__");
      if (error_state) return retval;

      if (is.is_open ()) {
            std::string mode = is.mode_as_string (is.mode ());
            // 114: "r", 43: "+"
            if (! strchr (mode.c_str (), 114) &&
                ! strchr (mode.c_str (), 43)) {
                  error ("__bw_prcv__: stream not readable\n");
                  return retval;
            }
#ifdef PATCHED_PIPE_CODE
            // If I understood right, Octaves pipe-ids have been
            // patched (at 15th June 2007 ?) to show "wb" and "rb"
            // instead of "w" and "b".

            // 98: "b"
            if (! strchr (mode.c_str (), 98)) {
                  error ("__bw_prcv__: stream not binary\n");
                  return retval;
            }
#endif
      }
      else {
            error ("__bw_prcv__: stream not open\n");
            return retval;
      }

      std::istream *tps = is.input_stream ();
      std::istream& ps = *tps;

      bool global = false;
      octave_value tc;
      std::string name;
      std::string doc;
      bool swap;
      oct_mach_info::float_format flt_fmt;

      // EOF at start of reading might happen in normal program flow.
      if (ps.peek () == EOF) {
            retval = 0;
            return retval;
      }

      // Any later EOF is not foreseen and should cause an error.

      // The next two functions called pretend to have been called
      // from 'load' in their error messages, read_binary_data also
      // wants to have the filename, but it may be a pipe ...
      if (read_binary_file_header (ps, swap, flt_fmt, false) < 0)
            return retval;
      name = read_binary_data (ps, swap, flt_fmt,
                         "",
                         global, tc, doc);
      // read_binary_data will give no error with EOF at start
      // of reading, but in this case it is an error, since
      // after the header exactly one variable is expected. This
      // is mended by asking for EOF here.
      if (ps.eof () || error_state || name.empty ()) {
            error ("__bw_prcv__: error in reading variable data\n");
            return retval;
      }
      if  (! tc.is_defined ()) {
            // What means this?
            error ("__bw_prcv__: error in reading variable\n");
            return retval;
      }

      retstruct.assign(name, tc);
      retval = retstruct;

      return retval;
}

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