Re: About the CLI of both grub-mkrescue versions

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

to substantiate my proposal of renaming young grub-mkrescue.c to
grub-mkiso.c and to add a built-in emulation of grub-mkrescue(.in),
here the necessary code which i tested standalone with valgrind.

The decision which parser to use would be made in main():

--------------------------------------------------------------

  char *cpt;
  ...
  /* Get leaf name of argv[0] */
  for (cpt = argv[0] + strlen (argv[0]) - 1; cpt >= argv[0]; cpt--)
    if (*cpt == '/')
      break;
  cpt++;
  if (strcmp (cpt, "grub-mkrescue") == 0)
    {
      arg_parser_mkrescue (argc, argv);
    }
  else
    {
      argp_parse (&argp, argc, argv, 0, 0, 0);
    }

--------------------------------------------------------------

The help text is derived from grub-mkrescue.in of GRUB 2.00.

--------------------------------------------------------------

static void
printc (char *line)
{
  printf ("%s\n", line);
}

static void
print_mkrescue_help (char *prog_name)
{
  printf ("%s %s %s\n", _("Usage:"), prog_name, _("[OPTION] SOURCE..."));
  printc (_("Make GRUB CD-ROM, disk, pendrive and floppy bootable image."));
  printc (_("-h, --help"));
  printc (_("        print this message and exit"));
  printc (_("-v, --version"));
  printc (_("        print the version information and exit"));
  printc (_("-o, --output=FILE"));
  printc (_("        save output in FILE [required]"));
  printc (_("--rom-directory=DIR"));
  printc (_("        save ROM images in DIR [optional]"));
  printc (_("--xorriso=FILE"));
  printc (_("        use FILE as xorriso [optional]"));
  printc (_("Not supported any more are:"));
  printc (_("        --modules , --grub-mkimage , --override-directory"));
  printc (_("Other arguments get forwarded to xorriso -as mkisofs"));
  printc (_("emulation."));
  printc ("");
  printf ("%s %s\n", prog_name, _("generates a bootable rescue image"));
  printc (_("with specified source files, source directories, or mkisofs"));
  printc (_("options listed by the output of `xorriso -as mkisofs -help'"));
  printc ("");
  printc (_("Note: Do not use option \"--\" unless you want to submit"));
  printc (_("      native xorriso commands instead of file paths or"));
  printc (_("      mkisofs options. See man xorrisofs and man xorriso."));
  printc ("");
  printc (_("Report bugs to <bug-grub@gnu.org>."));
  printc (_("Mail xorriso support requests to <bug-xorriso@gnu.org>."));
  printc ("");
  printc (_("This is program grub-mkiso emulating the option"));
  printc (_("interpretation of legacy program grub-mkrescue."));
  printc (_("grub-mkiso in its native mode has more advanced options."));
  printc (_("But that mode demands to separate grub-mkiso options"));
  printc (_("and xorriso options by a double dash \"--\", which xorriso"));
  printc (_("will not get to see."));
}

--------------------------------------------------------------

The parser function implements the promised options and collects
the xorriso -as mkisofs options into the same char pointer array
as does the existing parser in the C program.
In particular it sets the values of these variables:

static char *rom_directory;
static int xorriso_tail_argc;
static int xorriso_tail_arg_alloc;
static char **xorriso_tail_argv;
static char *output_image;
static char *xorriso;

--------------------------------------------------------------

static void
arg_parser_mkrescue (int argc, char *argv[])
{
  int i;

  for (i = 1; i < argc; i++)
    {
      if (strcmp (argv[i], "-h") == 0 || strcmp (argv[i], "--help") == 0)
        {
          print_mkrescue_help (argv[0]);
          exit (0);
        }
      else if (strcmp (argv[i], "-v") == 0
               || strcmp (argv[i], "--version") == 0)
        {
          printf ("%s %s %s\n", argv[0], PACKAGE_NAME, PACKAGE_VERSION);
          exit (0);
        }
      else if (strcmp (argv[i], "--modules") == 0)
        {
          grub_util_error (_("Option --modules is not supported any more"));
        }
      else if (strncmp (argv[i], "--modules=", 10) == 0)
        {
          grub_util_error (_("Option --modules= is not supported any more"));
        }
      else if (strcmp (argv[i], "-o") == 0
               || strcmp (argv[i], "--output") == 0)
        {
          if (i == argc - 1)
            grub_util_error (_("option requires an argument -- `%s'"),
                             argv[i]);
          i++;
          free (output_image);
          output_image = xstrdup (argv[i]);
        }
      else if (strncmp (argv[i], "--output=", 9) == 0)
        {
          free (output_image);
          output_image = xstrdup (argv[i] + 9);
        }
      else if (strcmp (argv[i], "--rom-directory") == 0)
        {
          if (i == argc - 1)
            grub_util_error (_("option requires an argument -- `%s'"),
                             argv[i]);
          i++;
          free (rom_directory);
          rom_directory = xstrdup (argv[i]);
        }
      else if (strncmp (argv[i], "--rom-directory=", 16) == 0)
        {
          free (rom_directory);
          rom_directory = xstrdup (argv[i] + 16);
        }
      else if (strcmp (argv[i], "--override-directory") == 0)
        {
          grub_util_error(
                   _("Option --override-directory is not supported any more"));
        }
      else if (strncmp (argv[i], "--override-directory=", 21) == 0)
        {
          grub_util_error(
                  _("Option --override-directory= is not supported any more"));
        }
      else if (strcmp (argv[i], "--xorriso") == 0)
        {
          if (i == argc - 1)
            grub_util_error (_("option requires an argument -- `%s'"),
                             argv[i]);
          i++;
          free (xorriso);
          xorriso = xstrdup (argv[i]);
        }
      else if (strncmp (argv[i], "--xorriso=", 10) == 0)
        {
          free (xorriso);
          xorriso = xstrdup (argv[i] + 10);
        }
      else
        {
          if (xorriso_tail_arg_alloc <= xorriso_tail_argc)
            {
              xorriso_tail_arg_alloc = 2 * (4 + xorriso_tail_argc);
              xorriso_tail_argv = xrealloc (xorriso_tail_argv,
                                      sizeof (xorriso_tail_argv[0])
                                      * xorriso_tail_arg_alloc);
            }
          xorriso_tail_argv[xorriso_tail_argc++] = xstrdup (argv[i]);
        }
    }
}

--------------------------------------------------------------

There remains the incompatibility that i could not find
equivalents of the following grub-mkrescue.in features:

  --modules=MODULES
          pre-load specified modules MODULES
  --grub-mkimage=FILE
          use FILE as grub-mkimage
  --override-directory
          "Intentionally undocumented"

--------------------------------------------------------------

The valgrind test was made with a mock-up of grub-mkiso.c
consisting of some copied util/grub-*.c functions and a main()
which prints the content of the variables after parsing.

  ln -s grub-mkiso grub-mkrescue
  valgrind ./grub-mkrescue -o output.iso -J --rom-directory=./ROMDIR -P YET_ANOTHER_OS.ORG --md5 --emul-toc ./my_os_payload --xorriso="$HOME"/xorriso-1.3.8/xorriso/xorriso

yielded:

  output_image=           'output.iso'
  rom_directory=          './ROMDIR'
  xorriso=                '/home/thomas/xorriso-1.3.8/xorriso/xorriso'
  xorriso_tail_arg_alloc= 8
  xorriso_tail_argc=      6
  xorriso_tail_argv[ 0]= '-J'
  xorriso_tail_argv[ 1]= '-P'
  xorriso_tail_argv[ 2]= 'YET_ANOTHER_OS.ORG'
  xorriso_tail_argv[ 3]= '--md5'
  xorriso_tail_argv[ 4]= '--emul-toc'
  xorriso_tail_argv[ 5]= './my_os_payload'
  ==9810== 
  ==9810== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 1)
  ...
  ==9810== LEAK SUMMARY:
  ==9810==    definitely lost: 0 bytes in 0 blocks.
  ==9810==      possibly lost: 0 bytes in 0 blocks.
  ==9810==    still reachable: 185 bytes in 10 blocks.
  ==9810==         suppressed: 0 bytes in 0 blocks.

The memory leaks are caused by allocated storage of global
variables.


Have a nice day :)

Thomas