Restore backward compatibility for "attach" verb.

[delphij]

Summary

In r332361 and r333439, two new parameters were added to geli attach
verb using gctl_get_paraml, which requires the value to be present.
This would prevent old geli(8) binary from attaching geli(4) device
as they have no knowledge about the new parameters.

Restore backward compatibility by treating the absense of these two
values as seeing the default value supplied by userland.

Test Plan

Use old geli(8) binary to attach geli(4) device.

[delphij]

Correct size for dryrun.

[oshogbo]

Thanks for catching that.

sys/geom/eli/g_eli_ctl.c

63

Assigning values here is incorrect with style(9).

87

Do we need to get values twice?
Wouldn't it work as:

valp = gctl_get_paraml(req, "keyno", sizeof(*valp));
if (valp != NULL)
    nkey = *valp;
else
    nkey = -1;

[delphij]

sys/geom/eli/g_eli_ctl.c

63

Thanks, will fix.

87

Yes because counter-intuitively, gctl_get_paraml would set error for non-existent parameters (while gctl_get_param won't, which is (ab)used as a check for whether the parameter was supplied).

[delphij]

Address style(9) issues pointed out by oshogbo.

[delphij]

Please take another look, thanks!