[sane-devel] Canon PIXMA MX330 working, with -x auto and -y auto bug; data here

Nicolas Martin nicolas0martin at gmail.com
Sun Dec 6 13:45:39 UTC 2009

Le dimanche 06 décembre 2009 à 10:50 +0100, Nicolas Martin a écrit :
> - There's an error with scanimage/pixma backend when setting explicitly
> -x or -y options to "auto". This is the same for all pixma devices, so
> probably something the pixma backend rejects for now, and that needs to
> be checked.

Just tried  with another scanner (Canon N656U handled by the plustek
backend) and got the same message when setting scanimage -x option to

Looking more deeply at scanimage.c source code, I notice this:

In main():

    case 'x':
      window_val_user[0] = 1;
      parse_vector (&window_option[0], optarg, &window_val[0], 1);

    case 'y':
      window_val_user[1] = 1;
      parse_vector (&window_option[1], optarg, &window_val[1], 1);

    case 'l':		/* tl-x */
      process_backend_option (device, window[2], optarg);

So here, (x, y) and (l, t) do not use obviously the same functions to be

Then, looking in parse_vector():

      /* read value */
      str = parse_scalar (opt, str, &value);

and finally in parse_scalar():

v = strtol (str, &end, 10);

if (str == end)
    fprintf (stderr,
       "%s: option --%s: bad option value (rest of option: %s)\n",
       prog_name, opt->name, str);
    exit (1);

So if -x value is "auto", the strtol will fail, and trig the error
message:  scanimage: option --x: bad option value (rest of option: auto)

More evidence of that if I enter the scanimage command like this:

$ scanimage --format pnm -x foo  > output.pnm
scanimage: option --x: bad option value (rest of option: foo)

In conclusion: the -x auto limitation seems to be due to scanimage. 

=> And now the questions, before changing anything: 

- Is there any reason for that, should the -x auto and -y auto options
be valid ?
- Does this need to be fixed, or is it working as designed ?
- Should we process (x, y) values as (l, t) are processed ?

All suggestions welcome.


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