convert_vms_vl.cxx

///
/// Convert VMS VL format file into UNIX format
/// @author Freddie Akeroyd, STFC ISIS Facility
///

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <fstream>
#include <unistd.h>

// convert 16 bit length field of VMS variable length(VL) to \n
int main(int argc, char* argv[])
{
    std::fstream f;
  int c;
  opterr = 0;
  bool nocc = false;
  const char* cvalue = "\n";

  while ((c = getopt (argc, argv, "nc:")) != -1)
    switch (c)
      {
      case 'n':
        nocc = true;
        break;
      case 'c':
        switch(optarg[0])
        {
            case 'l':
                cvalue = "\n";
                break;
            case 'm':
                cvalue = "\r";
                break;
            case 'w':
                cvalue = "\r\n";
                break;
            default:
                cvalue = "\n";
                break;
         }
         break;
      case '?':
        if (optopt == 'c')
          fprintf (stderr, "Option -%c requires an argument.\n", optopt);
        else if (isprint (optopt))
          fprintf (stderr, "Unknown option `-%c'.\n", optopt);
        else
          fprintf (stderr,
                   "Unknown option character `\\x%x'.\n",
                   optopt);
        return -1;
      default:
        return -1;
      }

    if ((argc - optind) < 1)
    {
        std::cerr << "No filename given" << std::endl;
        return -1;
    }
    if (nocc)
    {
        cvalue = "\0";
    }
    const char* filein = argv[optind];
    f.open(filein, std::ios::in | std::ios::binary);
    if (!f.good())
    {
        std::cerr << "File open error for \""  << filein << "\"" << std::endl;
        return -1;
    }
    f.seekg (0, f.end);
    int length = f.tellg();
    if (length % 2 != 0)
    {
        std::cerr << "File length not multiple of 2 bytes for file \"" << filein << "\"" << std::endl;
        return -1;
    }
    f.seekg (0, f.beg);
    char * buffer = new char [length+2];
    f.read (buffer,length);
    buffer[length] = '\0';
    buffer[length+1] = '\0';
    unsigned short* sbuffer = (unsigned short*)buffer;
    int slength = length / 2;
    int l, i;
    for(i = 0; i < slength; )
    {
        l = sbuffer[i]; // record length in bytes
        sbuffer[i] = cvalue[0] + 256 * cvalue[1]; // replace length with CC
        i += 1; // length field
        i += (l + 1) / 2; // record data, but padded to even byte number
        if (l % 2 != 0)
        {
            buffer[2*i-1] = '\0'; // overwrite padding byte, probably already a NULL
        }
    }
    if (i != slength)
    {
        std::cerr << "record length mismatch - maybe not OpenVMS VL file format? for file \"" << filein << "\"" << std::endl;
        return -1;
    }
    for(i = 2; i < length; ++i)
    {
        switch(buffer[i])
        {
            case '\0':
		break;

	    default:
		std::cout << buffer[i];
		break;
	}
    }
    // add final CC
    std::cout << cvalue;
    return 0;
}